JP7675683B2 - Belt-type continuously variable transmission control device and control method - Google Patents

Description

The present invention relates to a control device and a control method for a belt-type continuously variable transmission that includes a drive pulley to which a driving force is transmitted, a driven pulley, and a belt that is stretched between them.

Conventionally, in saddle-type vehicles, a belt-type continuously variable transmission is used between the internal combustion engine, which is the power source, and the drive wheels. The belt-type continuously variable transmission includes a drive pulley to which the drive force is transmitted, a driven pulley that transmits the power to the drive wheels, a V-belt stretched between them, and a mechanism for changing the groove width of the pulleys.

For example, in the V-belt type continuously variable transmission of Patent Document 1, a shift member is connected to the hub shaft of the movable pulley half of the drive pulley so as to rotate freely relative to the hub shaft but not to move axially relative to the hub shaft. An electric motor is attached so that its rotor shaft is parallel to the input shaft to which the drive pulley is attached, and a shift control mechanism is provided to operate the shift member in the axial direction via a reduction gear train. The shift control mechanism is made up of a screw shaft parallel to the input shaft and a female screw member with which the male screw portion of the screw shaft is screwed, and the screw shaft is supported via bearings on the inner and outer cases of the transmission case on the radial outside of the drive pulley. The female screw member is integrally connected to the tip of the arm of the shift member. Therefore, when the electric motor is operated and the screw shaft rotates forward, the female screw member is sent to move the shift member toward the top, bringing the movable pulley half closer to the fixed pulley half of the drive pulley. Conversely, when the screw shaft rotates in the reverse direction, the female screw member is sent to move the shift member in the low direction, moving the movable pulley half away from the fixed pulley half.

Patent Document 2 discloses an electronically controlled continuously variable transmission that uses feedback control to ensure that the gear ratio between the input shaft and the output shaft is a target gear ratio. It is disclosed that this continuously variable transmission uses a sheave position sensor for detecting the position of the movable sheave body of the primary sheave, a primary sheave rotational speed sensor, a secondary sheave rotational speed sensor, a vehicle speed sensor, and a throttle opening sensor to control the gear ratio.

JP 2013-029130 A Patent No. 5030608

The continuously variable transmission of Patent Document 2 has a large number of parts, such as sensors, which makes it difficult to layout the continuously variable transmission inside the transmission case and increases costs. The object of the present invention is to provide a configuration that makes it possible to control the continuously variable transmission to a target gear ratio while reducing the number of parts inside the transmission case.

The first aspect of the present invention is
A control device for a belt-type continuously variable transmission including: a drive pulley to which a driving force is transmitted from an output shaft of a power source of a vehicle; a driven pulley equipped with a centrifugal clutch which rotates integrally with the driven pulley and is connected to the driven pulley when a predetermined rotation speed is exceeded, thereby transmitting the driving force of the power source to a drive wheel of the vehicle; and a belt stretched between the drive pulley and the driven pulley,
a control unit for controlling a motor that generates a driving force in an axial direction of the movable pulley half so as to move the movable pulley half relative to the fixed pulley half in the drive pulley,
The control unit is
controlling the motor so as to maintain a gear ratio of the continuously variable transmission at a fixed gear ratio when the centrifugal clutch is in an incompletely engaged state;
and when the centrifugal clutch is in a fully engaged state, feedback control of the operation of the motor is performed based on the detected vehicle speed and the detected load of the power source.

According to the above configuration, when the centrifugal clutch is not fully connected, that is, when the centrifugal clutch is slipping or disengaged, the motor is controlled to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio. Therefore, when the centrifugal clutch is not fully connected, the motor can be controlled without the need to accurately grasp the driving state of the driven pulley, for example, its rotational speed, and the gear ratio of the continuously variable transmission can be controlled to a fixed gear ratio. Therefore, for example, it is possible to omit a sensor that detects the rotational speed of the driven pulley from inside the continuously variable transmission case. In this way, according to the above configuration, it is possible to control the gear ratio to a target ratio while reducing the number of parts in the transmission case. Note that when the above-mentioned centrifugal clutch is fully connected, when feedback control of the operation of the motor is performed based on the detected vehicle speed and the detected load of the power source, the feedback control is possible even if, for example, a sensor that detects the rotational speed of the driven pulley is not present in the transmission case.

Preferably, when controlling the motor to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio, the control unit executes limiting the magnitude of the motor current to a predetermined value or less and limiting the duty ratio of the control signal to the motor to a predetermined limit value or less. With this configuration, even if the movable pulley half hits, for example, a stopper portion, the duty ratio is limited to a predetermined limit value or less, so that the speed of movement of the movable pulley half can be slowed down and the collision load at the time of the hit can be suppressed, thereby protecting each component. Furthermore, by limiting the magnitude of the motor current to a predetermined value or less, it is possible to prevent the continuous current flowing to the motor from becoming excessive, thereby making it possible to protect the motor.

Preferably, when the motor is controlled to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio, the movable pulley half reaches a predetermined end in the axial direction of the movable pulley half. According to this configuration, when the motor is controlled to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio, the movable pulley half reaches a predetermined end in the axial direction of the movable pulley half, so that the speed ratio of the continuously variable transmission can be controlled to the fixed speed ratio with simpler control.

Preferably, when the centrifugal clutch is in an incompletely connected state, the control unit determines whether the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half based on the current of the motor, and when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, controls the motor to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio. According to this configuration, it is determined whether the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half based on the current of the motor. Therefore, it is possible to detect the arrival of the movable pulley half at the predetermined end without providing a sensor that directly detects the position of the movable pulley half, for example. Then, when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, the motor is controlled to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio. Therefore, in controlling the continuously variable transmission, it becomes possible to move the movable pulley half over a wide range, including the point where the movable pulley half reaches a specified end, thereby making it possible to further expand the movable range of the movable pulley half of the drive pulley.

Preferably, when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, the abutment portion on the movable pulley half abuts against a stopper portion that restricts the movement of the movable pulley half in the axial direction away from the fixed pulley half. This makes it possible to limit the abutment of the movable pulley half to the abutment portion and the stopper portion, and to more reliably protect other components.

A second aspect of the present invention is
A belt-type continuously variable transmission including a drive pulley to which a driving force is transmitted from an output shaft of a power source of a vehicle, a driven pulley equipped with a centrifugal clutch which rotates integrally with the driven pulley and is connected when a predetermined rotation speed is exceeded to transmit the driving force of the power source to a drive wheel of the vehicle, and a belt stretched between the drive pulley and the driven pulley, the control method comprising: controlling a motor which generates a driving force in an axial direction of a movable pulley half so as to move the movable pulley half relative to a fixed pulley half in the drive pulley,
controlling the motor so as to maintain a gear ratio of the continuously variable transmission at a fixed gear ratio when the centrifugal clutch is in an incompletely engaged state;
and when the centrifugal clutch is in a fully engaged state, feedback controlling the operation of the motor based on the detected vehicle speed and the detected load of the power source.

According to the configuration of the second aspect, when the centrifugal clutch is not fully connected, that is, when the centrifugal clutch is slipping or disengaged, the motor is controlled to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio. Therefore, when the centrifugal clutch is not fully connected, the motor can be controlled without the need to accurately grasp the driving state of the driven pulley, for example, its rotational speed, and the gear ratio of the continuously variable transmission can be controlled to a fixed gear ratio. Therefore, for example, it is possible to omit a sensor that detects the rotational speed of the driven pulley from inside the continuously variable transmission case. In this way, according to the above configuration, it is possible to control the gear ratio to a target ratio while reducing the number of parts in the transmission case. Note that when the above-mentioned centrifugal clutch is fully connected, when feedback control of the operation of the motor is performed based on the detected vehicle speed and the detected load of the power source, the feedback control is possible even if, for example, a sensor that detects the rotational speed of the driven pulley is not present in the transmission case.

Preferably, the second aspect further includes a step of limiting the magnitude of the motor current to a predetermined value or less and limiting the duty ratio of the control signal to the motor to a predetermined limit value or less when controlling the motor to maintain the speed ratio of the continuously variable transmission at a fixed speed ratio. According to this configuration, even if the movable pulley half hits, for example, a stopper, the duty ratio is limited to a predetermined limit value or less, so that the speed of movement of the movable pulley half can be slowed down and the collision load at the time of the hit can be suppressed, thereby protecting each component. Furthermore, by limiting the magnitude of the motor current to a predetermined value or less, it is possible to prevent the continuous current flowing to the motor from becoming excessive, thereby making it possible to protect the motor.

Preferably, in the second aspect, when the centrifugal clutch is in an incompletely connected state, the step of controlling the motor to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio includes a step of determining, based on the current of the motor, whether or not the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half when the centrifugal clutch is in an incompletely connected state, and a step of controlling the motor to maintain the gear ratio of the continuously variable transmission at a fixed gear ratio when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half. According to this configuration, it is determined, based on the current of the motor, whether the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half. Therefore, for example, it is possible to detect the arrival of the movable pulley half at the predetermined end without providing a sensor that directly detects the position of the movable pulley half. Then, when it is determined that the movable pulley half has reached the predetermined end in the axial direction of the movable pulley half, the motor is controlled to maintain the gear ratio of the continuously variable transmission at the fixed gear ratio. Therefore, in controlling the continuously variable transmission, it becomes possible to move the movable pulley half over a wide range, including the point where the movable pulley half reaches a specified end, thereby making it possible to further expand the movable range of the movable pulley half of the drive pulley.

According to the first or second aspect of the present invention, the above configuration is provided, so that in controlling the continuously variable transmission, it is possible to control the transmission to a target gear ratio while reducing the number of parts in the transmission case.

FIG. 1 is a schematic left side view of a motorcycle equipped with a power unit equipped with a belt-type continuously variable transmission according to one embodiment of the present invention. FIG. 2 is a front view of the power unit of FIG. FIG. 3 is an exploded sectional view of the power unit taken along the line III-III in FIG. FIG. 4 is an enlarged view of the drive pulley and its drive system shown in FIG. FIG. 5 is an enlarged view of the drive pulley and its drive system in FIG. 3, showing the movable drive pulley half body when it has moved as shown by the dashed line in FIG. FIG. 6 is a front view of a movable holder in the belt-type continuously variable transmission of FIG. 7 is a perspective view of an inner boss of a cam assist mechanism in the belt-type continuously variable transmission of FIG. 1. FIG. FIG. 8 is a perspective view showing a state in which a ball member is disposed on an inner boss of a cam assist mechanism in the belt-type continuously variable transmission of FIG. FIG. 9 is a perspective view showing a portion of an outer boss around an inner boss in which the ball of FIG. 8 is disposed. FIG. 10 is a cross-sectional view taken along line XX in FIG. 11 is a perspective view of an outer boss of a cam assist mechanism in the belt-type continuously variable transmission of FIG. 1. FIG. 12 is a cross-sectional view taken at the position of one ball member in the cam assist mechanism of the belt-type continuously variable transmission of FIG. 1. FIG. 13 is a simplified diagram showing the relationship between a groove portion and an axis line, as viewed from the arrow XIII in FIG. 7, in an inner boss of the cam assist mechanism in the belt-type continuously variable transmission in FIG. 1. FIG. 14 is a perspective view of a case that houses a drive mechanism in the belt-type continuously variable transmission of FIG. 1 and a part of its surroundings, seen obliquely from the front. 15 is a perspective view of a case that houses a drive mechanism in the belt-type continuously variable transmission of FIG. 1 and a part of its surroundings, seen obliquely from behind. FIG. 16 is a diagram showing a gear arrangement of a drive mechanism in the belt-type continuously variable transmission of FIG. 1, and is a diagram showing the left side of a case in which the drive mechanism is housed, as viewed from the axial direction. FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. FIG. 18 is a block diagram of the control device for the motorcycle shown in FIG. FIG. 19 is a graph showing data for controlling the motor of the drive mechanism in the belt-type continuously variable transmission of FIG. FIG. 20 is a flow chart of the control of the motor of the drive mechanism in the belt type continuously variable transmission of FIG. FIG. 21 is a timing chart relating to the control of the motor of the belt-type continuously variable transmission of FIG. FIG. 22 is a timing chart relating to the control of the motor of the belt-type continuously variable transmission of FIG. FIG. 23 is a timing chart relating to the control of the motor of the belt-type continuously variable transmission of FIG.

The following describes an embodiment of the present invention with reference to the drawings.

A belt-type continuously variable transmission 10 according to one embodiment will be described with reference to Figures 1 to 15. Note that the directions of front, rear, left, right, up and down in the description and claims of this specification correspond to the directions of a saddle-type vehicle equipped with a power unit P equipped with a belt-type continuously variable transmission 10 according to this embodiment. In this embodiment, the saddle-type vehicle is specifically a scooter-type motorcycle (hereinafter simply referred to as "motorcycle") 1. In addition, in the drawings, the arrow FR indicates the front of the saddle-type vehicle according to this embodiment, LH indicates the left side of the vehicle, RH indicates the right side of the vehicle, and UP indicates the top of the vehicle.

Figure 1 shows an overview of the left side of a motorcycle 1 equipped with a power unit P that employs a belt-type continuously variable transmission 10 according to this embodiment. Figure 2 is an enlarged view of the power unit P in Figure 1. Figure 3 is a cross-sectional development of the power unit P along III-III in Figure 1. Figures 4 and 5 are enlarged views of a portion of the belt-type continuously variable transmission 10 in Figure 3, and are diagrams showing the movement of the belt-type continuously variable transmission 10.

In the motorcycle 1 of this embodiment, the front body 1f and the rear body 1r are connected via a low floor section 1c, and the body frame that forms the skeleton of the vehicle body is generally composed of a down tube 3 and a main pipe 4. That is, the down tube 3 extends downward from the head pipe 2 of the front body 1f, the down tube 4 bends horizontally at its lower end and extends rearward below the floor section 1c, and a pair of left and right main pipes 4 are connected at their rear ends, and the main pipes 4 rise upward from the connecting section, bend, and extend diagonally rearward.

A seat 5 is disposed above the main pipe 4. Meanwhile, at the front body 1f, a handlebar 6 is provided above and journaled on the head pipe 2, and a front fork 7 extends below, with a front wheel Wf journaled at its lower end. A power unit P is mounted on the motorcycle 1 and supported by the main pipe 4.

The main stand 8 is provided below the power unit P so that it can be raised and lowered freely. The main stand 8 has an operating arm 8b that extends to the left from a leg 8a, and a footrest plate 8c at its tip.

The power unit P has an internal combustion engine E at the front and a power transmission section T that extends rearward from the internal combustion engine E to the left of the rear wheel Wr. As shown in FIG. 3, the power transmission section T includes a transmission case 12 that extends rearward from the internal combustion engine E and a transmission case cover 16 that covers the transmission case 12 from the outside in the vehicle width direction and forms a belt chamber 14, and the belt chamber 14 houses the belt-type continuously variable transmission 10. An outer cover 18 is provided on the left outer side of the transmission case cover 16 (see FIGS. 1 and 2).

The internal combustion engine E, which is the power source, is a single-cylinder, four-stroke internal combustion engine, and the cylinder block 24, cylinder head 26, and cylinder head cover 28 protrude forward from the crankcase 22, which supports the crankshaft 20 oriented in the vehicle width direction, and are tilted forward to a position that is nearly horizontal.

A pair of left and right support brackets extend downward from the bottom end of the crankcase 22, and these support brackets are connected to a bracket 32 that protrudes rearward from the front lower part of the main pipe 4 via a link member 34, so that the power unit P is connected and supported so that it can swing relative to the vehicle body.

The power transmission section T extends rearward from the internal combustion engine E in the power unit P, and the rear wheels Wr, which are driving wheels, are mounted on the rear axle 36, which is the output shaft of the reduction gear mechanism Tr provided at the rear of the power transmission section T.

A rear cushion 9 is interposed between a support bracket 38 erected at the rear end of the power transmission section T and the rear of the main pipe 4.

An intake pipe 40 extends from the top of the cylinder head 26 of the internal combustion engine E, which is tilted forward significantly, then curves backward and reaches an air cleaner 44 above the belt-type continuously variable transmission 10 via a throttle body 42 equipped with a throttle valve 42v. A fuel injection valve 45 is provided in the intake pipe 40. Meanwhile, an exhaust pipe 46 extends downward from the bottom of the cylinder head 26, bends backward, leans to the right, and extends backward to connect to a muffler 48 on the right side of the rear wheel Wr.

As shown in Figure 3, which shows a cross-sectional view of the power unit P taken along line III-III in Figure 1, the crankcase 22, which supports the crankshaft 20 while orienting it in the vehicle width direction, is made up of a right-side crankcase 22r and a front portion 12a of the transmission case 12, which extends long from front to rear on the left side, joined together on the left and right.

The transmission case 12 has a rear part 12b that extends rearward from the front part 12a to the left side of the rear wheel Wr, forming an oval bowl shape that is long from front to back and opens to the left. A transmission case cover 16 is placed over the open face on the left side of the transmission case 12, forming a belt chamber 14 inside, and as described above, the belt-type continuously variable transmission 10 is housed in this belt chamber 14. The right open face of the rear part 12b of the transmission case 12 is covered by a reduction gear cover 50, forming a reduction gear chamber 52 inside which the reduction gear mechanism Tr is housed. The power transmission section T is formed including the reduction gear mechanism Tr provided in the rear part 12b.

Inside the so-called crankcase 22, formed by the combination of the right crankcase 22r and the front part 12a of the transmission case 12, the crankshaft 20 is rotatably supported by the side walls of the right crankcase 22r and the front part 12a of the transmission case 12 via main bearings 54 and 55, which are left and right rolling bearings.

In the internal combustion engine E, a connecting rod 58 connects a piston 56 that reciprocates within the cylinder liner 24a of the cylinder block 24 to a crank pin 21 of the crankshaft 20.

A cam chain drive sprocket 60 is fitted to the right outer shaft portion of the crankshaft 20, which extends horizontally to the left and right, so as to be able to rotate integrally therewith, and an AC generator 62 is provided at its right end, while a drive pulley 64 for the belt-type continuously variable transmission 10 is provided on the left outer shaft portion. In other words, the crankshaft 20 is the output shaft of the internal combustion engine E, and the crankshaft 20, particularly its outer shaft portion, is the input shaft for the belt-type continuously variable transmission 10.

The four-stroke internal combustion engine E of this embodiment employs an SOHC type valve system, and a valve mechanism 66 is provided inside the cylinder head cover 28. A cam chain 68 that transmits power to the valve mechanism 66 is installed between the camshaft 70 and the crankshaft 20. A cam chain chamber 72 for this purpose is provided in communication with the right crankcase 22r, the cylinder block 24, and the cylinder head 26. In other words, the cam chain 68 is installed through the cam chain chamber 72 between the cam chain driven sprocket 74 fitted to the right end of the camshaft 70 oriented horizontally to the left and right, and the cam chain drive sprocket 60 fitted to the crankshaft 20.

The drive pulley 64 provided on the left outer shaft portion of the crankshaft 20 in the belt-type continuously variable transmission 10 of the power unit P includes a fixed drive pulley half 64a fitted near the left end of the crankshaft 20 and a movable drive pulley half 64b that faces the fixed drive pulley half 64a on the right side and is axially slidable. The fixed pulley half of the drive pulley 64 is the fixed drive pulley half 64a, and the movable pulley half is the movable drive pulley half 64b. In this specification, the axial direction means the direction along the axis 20A of the crankshaft 20 in the power unit P, that is, the axial direction of the crankshaft 20, unless otherwise specified.

The movable drive pulley half 64b is moved axially by cooperation between the variable speed drive mechanism D and the cam assist mechanism C, so that it can move toward or away from the fixed drive pulley half 64a. The variable speed drive mechanism D and the cam assist mechanism C will be described in detail later, but the cam assist mechanism C will first be briefly described here.

The cam assist mechanism C is of the ball cam type and includes an inner boss 80, an outer boss 88, and a ball member 150 that is arranged to engage with them.

As shown in Figures 3 to 5, particularly Figures 4 and 5, the sleeve 78, cylindrical inner boss 80, sleeve 82, and fixed drive pulley half 64a are fitted from the right to the left extension from the step 76 on the left side of the main bearing 55 on the left side of the crankshaft 20, which changes to a small diameter. By fastening the sleeve 78, inner boss 80, sleeve 82, and fixed drive pulley half 64a to the crankshaft 20 by fastening with a nut 86 via a washer 84 to the left end face of the crankshaft 20, the sleeve 78, inner boss 80, sleeve 82, and fixed drive pulley half 64a are fastened to the crankshaft 20, and are integrated with the crankshaft 20. Therefore, the fixed drive pulley half 64a and the inner boss 80 are each fixed integrally with the crankshaft 20 and rotate integrally with the crankshaft 20. At least one of the sleeve 78 and the sleeve 82 may be formed integrally with the inner boss 80.

On the other hand, the movable drive pulley half 64b, which faces the fixed drive pulley half 64a on the right side, is integrally provided with a cylindrical outer boss 88 that serves as its base. The outer boss 88 is arranged so that its inner peripheral surface 88i is in sliding contact with the outer peripheral surfaces of the sleeve 78 and the sleeve 82 and can move axially relative to the inner boss 80. A ball member 150 is provided on the outer boss 88, and the ball member 150 can roll on the outer peripheral surface 80a of the inner boss 80. As described later, the rolling surface of the ball member 150 of the inner boss 80 extends spirally around the axis of the inner boss 80, i.e., the axis 20A of the crankshaft 20, so that the outer boss 88 can rotate relative to the inner boss 80 within a predetermined range and can also move axially in conjunction with the rotation. The relative rotation of the outer boss 88 with respect to the inner boss 80 is restricted to a predetermined range so as to convert the rotational motion of the crankshaft 20 into the axial motion of the crankshaft 20. Therefore, when an axial driving force is applied by the variable speed drive mechanism D (described later) and the movable drive pulley half 64b approaches or moves away from the fixed drive pulley half 64a, the outer boss 88 with which the movable drive pulley half 64b is integrally formed rotates substantially around the crankshaft 20 while simultaneously moving in the axial direction.

In this way, the right-side movable drive pulley half 64b, which faces the left-side fixed drive pulley half 64a, can rotate around the crankshaft 20 and move axially to approach or move away from the fixed drive pulley half 64a. A V-belt 90 is sandwiched and wound between the opposing tapered surfaces of the two drive pulley halves 64a and 64b.

The driven pulley 94, which is rotatably supported on the driven shaft 92, which is the input shaft of the reduction gear mechanism Tr, behind the drive pulley 64, comprises a fixed driven pulley half 94a and a movable driven pulley half 94b that faces the fixed driven pulley half 94a on the left side and can slide in the axial direction.

An inner sleeve 96 is supported on the driven shaft 92 via a bearing so that it can rotate freely relative to the driven shaft 92 while its axial movement is restricted, and a fixed driven pulley half 94a is integrally fixed to the right end flange of the inner sleeve 96 by welding the center hole.

An outer sleeve 98 is fitted around the outer circumference of the inner sleeve 96 of the fixed driven pulley half 94a, and a guide pin protruding from the inner sleeve 96 fits into a long hole formed in the outer sleeve 98 in the axial direction, allowing the outer sleeve 98 to move axially relative to the inner sleeve 96, but restricting relative rotation.

The movable driven pulley half 94b is fixed integrally to the right end flange of this outer sleeve 98 by welding its center hole. Therefore, the movable driven pulley half 94b rotates together with the fixed driven pulley half 94a, but can also move axially toward and away from the fixed driven pulley half 94a.

The clutch inner 102 of the centrifugal clutch 100 is fixed to the left end of the inner sleeve 96 with a nut, and a coil spring 101 is interposed between the clutch inner 102 and the movable driven pulley half 94b, and the coil spring 101 urges the movable driven pulley half 94b to the right.

The belt-type continuously variable transmission 10 transmits power by a V-belt 90 stretched between the drive pulley 64 and the driven pulley 94. In the belt-type continuously variable transmission 10, the speed change drive mechanism D operates in response to the engine rotation speed, which causes the movable drive pulley half 64b to move relative to the fixed drive pulley half 64a, changing the winding diameter of the V-belt 90 around the drive pulley 64. At the same time, this causes a change in the winding diameter around the driven pulley 94, automatically changing the gear ratio and achieving continuously variable speed change.

The centrifugal clutch 100 is provided with a cup-shaped clutch outer 104 that covers the outer periphery of the clutch inner 102, the base of which is fixed near the left end of the driven shaft 92 by a nut 106, and a clutch shoe 112 that is biased by a spring 108 to the clutch inner 102 and pivotally supported on a support shaft 110 is disposed facing the inner periphery of the clutch outer 104.

The inner clutch 102 of the centrifugal clutch 100 rotates integrally with the infinitely variable driven pulley 94 of the belt-type continuously variable transmission 10. When the rotation speed exceeds a predetermined speed, the clutch shoe 112 of the inner clutch 102 swings against the spring 108 due to centrifugal force and comes into contact with the inner circumferential surface of the outer clutch 104, rotating the outer clutch 104 integrally and transmitting power to the driven shaft 92.

The driven shaft 92 is supported by the transmission case 12 and the transmission case cover 16 via bearings 113 and 114, and its right end inserted into the reduction gear chamber 52 on the right rear side of the transmission case 12 is supported by the reduction gear cover 116 via a bearing 117.

The reduction gear mechanism Tr in the reduction gear chamber 52 has a reduction intermediate shaft 118 between the driven shaft 92 and the rear axle 36, which are oriented parallel to each other (horizontally left and right) and supported by the transmission case 12 and the reduction gear cover 116, and the gears of each shaft form the reduction gear mechanism Tr. Therefore, the rotation of the driven shaft 92 is reduced in speed via the reduction gear mechanism Tr and transmitted to the rear axle 36, causing the rear wheels Wr, which are the drive wheels, to rotate. In this way, the centrifugal clutch 100, which rotates integrally with the driven pulley 94, engages when the rotation speed exceeds a predetermined speed, transmitting the driving force of the power source, here the internal combustion engine E, to the rear wheels Wr, which are the drive wheels of the vehicle.

When the belt-type continuously variable transmission 10 is operating in conjunction with the operation of the internal combustion engine E, the cooling fan 64f formed integrally on the left side of the fixed drive pulley half 64a also rotates together with the fixed drive pulley half 64a. As a result, outside air taken in from the outside air intake 18a (see Figures 1 and 2) provided on the outer cover 18 facing the side of the vehicle is introduced into the belt chamber 14 inside the transmission case cover 16 through the cooling air inlet of the transmission case cover 16. The flow of cooling air inside the belt chamber 14 is shown diagrammatically by arrows in Figure 2.

As described above, the belt-type continuously variable transmission 10 transmits power by a V-belt 90 stretched between the drive pulley 64 and the driven pulley 94. In the belt-type continuously variable transmission 10, the movable drive pulley half 64b moves axially relative to the fixed drive pulley half 64a due to the operation of the speed change drive mechanism D in response to the engine rotation speed, changing the winding diameter of the V-belt 90 on the drive pulley 64, and the winding diameter on the driven pulley 94 changes at the same time, automatically changing the speed change ratio and continuously changing the speed. Here, the speed change drive mechanism D will be described in detail mainly based on Figures 3 to 6. The speed change drive mechanism D corresponds to the drive mechanism in the present invention and includes a motor, that is, a speed change drive motor 120. The speed change drive mechanism D is configured to generate a driving force in the axial direction of the movable drive pulley half 64b so as to move the movable drive pulley half 64b relative to the fixed drive pulley half 64a in the drive pulley 64. The axial direction of the movable drive pulley half 64b is the axial direction of the drive pulley 64, which coincides with the axial direction of the crankshaft 20.

The transmission drive mechanism D is positioned on the front left side of the front part 12a of the transmission case 12. The transmission drive mechanism D is provided in a unit case 122 together with the cam assist mechanism C. The motor 120 of the transmission drive mechanism D is housed in the unit case 122, and the reduction mechanism 124 of the transmission drive mechanism D is attached to the unit case 122. The unit case 122 is divided into left and right halves, and is composed of a right case 122a that faces the front part 12a of the transmission case 12 on the left side, and a left case 122b that is fixed to the right case 122a by a bolt 123. The motor 120, reduction mechanism 124, and axial feed mechanism M are arranged in this order from the radial outside around the crankshaft 20. The cam assist mechanism C is arranged radially inside the axial feed mechanism M.

The unit case 122 is shaped so that the left extension is inserted from the step 76 on the left side of the main bearing 55 on the left side of the crankshaft 20, which changes to a smaller diameter, and the right case 122a is formed with a through hole (hereafter referred to as shaft through hole) 122i through which the crankshaft 20 is inserted, and the left case 122b is also formed with a through hole (hereafter referred to as shaft through hole) 122h through which the crankshaft 20 is inserted.

The motor 120 is positioned on the vehicle front FR side in the speed change drive mechanism D. The motor 120 is arranged in the left case 122b so that the drive shaft 120a of the motor 120 is parallel to the crankshaft 20, and a drive gear 120b is formed on the drive shaft 120a of the motor 120. Both ends of the first reduction gear shaft 130s are journaled via bearings 126, 128 in the bearing recesses 122c and 122d facing each other on the inside of the unit case 122, and the large diameter gear 130a integral with the first reduction gear shaft 130s meshes with the drive gear 120b of the drive shaft 120a of the motor 120. The first reduction gear shaft 130s is arranged parallel to the drive shaft 120a of the motor 120. The first reduction gear shaft 130s is also provided with a small diameter gear 130b that is integral with the first reduction gear shaft 130s and aligned axially with the large diameter gear 130a. The first reduction gear 130 in the reduction mechanism 124 is configured with the first reduction gear shaft 130s, the large diameter gear 130a, and the small diameter gear 130b.

The reduction mechanism 124 includes a second reduction gear 132 in addition to the first reduction gear 130. The second reduction gear 132 includes a large-diameter gear 132a that meshes with a small-diameter gear 130b of the first reduction gear shaft 130s. The large-diameter gear 132a includes a cylindrical portion 132b that extends from the large-diameter gear 132a to one side, i.e., to the right in Figs. 3 to 5, along the central axis of the large-diameter gear 132a. A gear shaft portion 134a on the right end side of the screw member 134 is press-fitted into the cylindrical portion 132b along the axis of the second reduction gear 132, i.e., the large-diameter gear 132a. Therefore, the large-diameter gear 132a is fixed integrally to the screw member 134.

The cylindrical portion 132b, into which the gear shaft portion 134a is press-fitted so as to pass through the center, is positioned in a state in which it is inserted into the axial through-hole 122e of the right case 122a of the unit case 122. At this time, two bearings 136, 138 are provided on the outer periphery of the cylindrical portion 132b of the second reduction gear 132 so that the right case 122a is sandwiched between the two bearings 136, 138. Note that in the right case 122a, the through-hole 122e is positioned radially outward of the shaft through-hole 122i.

At the tip of the cylindrical portion 132b of the second reduction gear 132, that is, at the outer end of the right case 122a, a rolling bearing 136 is provided between the step portion 122f near the through hole 122e of the right case 122a. The bearing 136 is configured to be able to receive radial loads. More specifically, the bearing 136 is configured to be able to receive not only radial loads but also axial loads. A collar 133, which is a cylindrical member, is provided to continue from the tip of the cylindrical portion 132b of the second reduction gear 132, and the tip side of the gear shaft portion 134a of the screw member 134 is inserted into the collar 133, and the bearing 136 is provided on the radial outside of the cylindrical portion 132b and the collar 133. As shown in Figs. 3 to 5, a nut 140 is screwed onto the male threaded portion 134b at the tip of the gear shaft portion 134a of the screw member 134 and tightened, so that the bearing 136 is fixed between the nut 140 and the hole wall portion 122g that defines the through hole 122e of the right case 122a. Meanwhile, a bearing 138, which is a large diameter needle bearing, is provided at the base end of the cylindrical portion 132b of the second reduction gear 132, i.e., at the left end near the large diameter gear 132a. The bearing 138 is a thrust roller bearing here, and is configured to be able to receive an axial load. The bearing 138 is provided so as to be sandwiched between the large diameter gear 132a and the hole wall portion 122g that defines the through hole 122e of the right case 122a in the axial direction and in contact with them. The second reduction gear 132, which is thus provided with the bearings 136 and 138, is attached to the right case 122a in such a way that it can rotate relative to the right case 122a but cannot move axially by screwing a nut 140 onto the male threaded portion 134b at the tip of the gear shaft portion 134a, which is press-fitted into the second reduction gear 132, and then tightening the nut 140.

The screw member 134, which is attached to the right case 122a so as to be rotatable relative to the right case 122a but immovable in the axial direction, has, in order from the right in Figs. 3 to 5, the male screw portion 134b, the gear shaft portion 134a, the flange portion 134c, and the male screw portion 134d, which are arranged in the axial direction of the screw member 134. The second reduction gear 132, i.e., the large diameter gear 132a, abuts against the flange portion 134c on its left side. Therefore, the screw member 134 is held by the bearings 136 and 138 with the right case 122a sandwiched between them. Therefore, for example, when a radial load is generated by a force acting on the screw member 134, or when an axial load is generated in the left direction, the load can be received by the bearing 136, and when a force is acting on the screw member 134 and an axial load is generated in the right direction, the load can be received by the bearing 138. Furthermore, the screw member 134 uses the nut 140 and the flange portion 134c to prevent the bearings 136 and 138 from coming loose, which improves the allowable axial load, i.e., the allowable thrust load, and increases the resistance to the screw member 134 coming loose.

The speed change drive mechanism D further includes a movable holder 142 that is movable in the axial direction. A plan view of the movable holder 142 as viewed from the left side in FIGS. 3 to 5 is shown in FIG. 6. The movable holder 142 is doughnut-shaped and includes a through hole 142a that extends in the axial direction at its center. The crankshaft 20 and the cam assist mechanism C provided around it are disposed in the through hole 142a. A bearing 144, which is a rolling bearing, is held by the bearing holding portion 88c, which is a holding portion on the outer periphery of the outer boss 88 of the cam assist mechanism C, and by the holding portion 142b provided on the wall portion that defines the through hole 142a of the movable holder 142. The movable holder 142 is supported by the bearing 144 so that it can rotate relative to the crankshaft 20. The movable holder 142 is disposed in the shaft through hole 122h of the left case 122b of the unit case 122, and an X-ring 146, which is a sealing member, is sandwiched and sealed between the outer circumferential surface 142c of the movable holder 142 and the shaft through hole 122h of the left case 122b of the unit case 122. An O-ring, an oil seal, or the like may also be used as the sealing member.

The male threaded portion 134d on the left side of the flange portion 134c of the screw member 134 is screwed into the female threaded hole 142d, which is the female threaded portion of the movable holder 142. The screw member 134 and the movable holder 142 form an axial feed mechanism (axial feed mechanism) M. The male threaded portion 134d is a trapezoidal thread, which is suitable for transmitting motion. In the movable holder 142, the female threaded hole 142d is provided radially outside the through hole 142a and radially inside its outer circumferential surface 142c. The male threaded portion 134d of the screw member 134 enters and screws into the female threaded hole 142d from the right side. The left end of the female threaded hole 142d is sealed with a cap member 148.

Therefore, in the variable speed drive mechanism D, when the variable speed drive motor 120 is driven and the drive gear 120b formed on the drive shaft 120a rotates, the large diameter gear 130a of the first reduction gear shaft 130s that meshes with the drive gear 120b rotates at a reduced speed together with the small diameter gear 130b, and the large diameter gear 132a that meshes with this small diameter gear 130b rotates and further decelerates together with the male threaded portion 134d of the screw member 134, which has a smaller diameter than the large diameter gear 132a. The rotation of the male threaded portion 134d causes the meshing between the male threaded portion 134d and the female threaded hole 142d of the movable holder 142 to shift axially, thereby moving the movable holder 142 in the axial direction. In this way, the movable holder 142 moves axially when the speed change drive motor 120 is driven forward and backward, and the outer boss 88 of the cam assist mechanism C described above moves relative to the inner boss 80, and as shown by the solid and dashed lines in FIG. 3 and as shown in FIGS. 4 and 5, the movable drive pulley half 64b can approach or move away from the fixed drive pulley half 64a. This changes the winding diameter of the V-belt 90 wound between the opposing tapered surfaces of the two drive pulley halves 64a and 64b, thereby performing infinitely variable speed changes.

The reduction mechanism 124 has an arrangement with three shafts: the drive shaft 120a of the motor 120, the first reduction gear shaft 130s of the first reduction gear 130, and the gear shaft portion 134a of the second reduction gear 132. This allows the diameter of each gear to be reduced, and as a result, the radial protrusion of the reduction mechanism 124 from the crankshaft 20 can be reduced.

Here, the cam assist mechanism C will be further described. As described above, the cam assist mechanism C is of the ball cam type, and includes the inner boss 80, the outer boss 88, and the ball member 150 provided thereon. As described above, the sleeve 78, the inner boss 80, the sleeve 82, and the fixed drive pulley half 64a are fitted from the right to the left extension from the step portion 76 of the crankshaft 20 in this order. The inner boss 80 is integral with the crankshaft 20, rotates with the crankshaft 20, and is immovable in the axial direction relative to the crankshaft 20. In contrast, the outer boss 88 is arranged so as to be slidable along the outer peripheral surface 80a of the inner boss 80, and the movable drive pulley half 64b provided on the outer boss 88 substantially rotates around the crankshaft 20 together with the outer boss 88 when the outer boss 88 slides against the inner boss 80, and at the same time moves in the axial direction. The ball member 150 is provided to cause axial movement due to the rotation of the outer boss 88. That is, the cam assist mechanism C includes an inner boss 80, which is an inner member that is arranged to be rotatable integrally with the crankshaft 20 of the internal combustion engine E, which is the output shaft of the power source, an outer boss 88, which is an outer member that is movable axially along the outer circumferential surface of the inner boss 80 together with the movable driving pulley half 64b, and a ball member 150 that causes the outer boss 88 to rotate and move axially relative to the inner boss 80. Note that the number of ball members 150 is four here, but it may be at least one.

A perspective view of the inner boss 80 is shown in FIG. 7. FIG. 7 is a view of the inner boss 80 as seen from the internal combustion engine E side in FIG. 3. Note that in FIG. 7, the directional arrows RH and LH in FIG. 3 are also added. The inner boss 80 is cylindrical, and the rolling surfaces 80f of the ball members 150 are formed on its outer circumferential surface 80a. Since four ball members 150 are used here, the same number of grooves 80b as the number of ball members 150 (here, four rolling surfaces 80f) are formed on the outer circumferential surface 80a of the inner boss 80. Each groove 80b has an arc-shaped cross section and extends spirally around the axis of the inner boss 80. The spiral shape of this rolling surface 80f, i.e., the groove 80b, is determined so that it twists in a direction against the rotation direction R of the crankshaft 20 toward the left axial direction, i.e., the fixed drive pulley half 64a side, in the arrangement of the inner boss 80 shown in FIGS. 3 to 5 and 7. The radius of curvature of the rolling surface 80f of each groove portion 80b is 0.1 mm to 0.7 mm larger than the radius of curvature of the spherical ball member 150.

Figure 8 shows the arrangement of ball members 150 corresponding to each groove portion 80b. The ball members 150, which are arranged so that they can run in the groove portion 80b of the inner boss 80, are provided in the hole portion 88a of the outer boss 88. Figure 9 shows the outer boss 88 arranged on the outside of the inner boss 80 in Figure 8, and Figure 10 shows a cross-sectional view at a position passing through the center of the ball members 150, that is, a cross-sectional view taken along line X-X in Figure 9. Figure 11 shows a perspective view of the outer boss 88, and the directional arrows RH and LH in Figure 3 are also added in Figure 11. However, in Figures 9 and 10, only a portion of the outer boss 88 is shown cut out. When the cam assist mechanism C is provided on the crankshaft 20 as shown in Figures 3 to 5, the axis 20A of the crankshaft 20 coincides with the axis of the inner boss 80 and also coincides with the axis of the outer boss 88, so in Figures 7 to 11, the axis 20A of the crankshaft 20 is shown as the axis of the inner boss 80 or the outer boss 88.

The outer boss 88 is cylindrical and includes, from the right side in Figs. 3 to 5 and 11, a tip portion 88b, an intermediate portion 88m including a bearing holding portion 88c, and a pulley mounting portion 88d. The tip portion 88b has the smallest diameter, and the diameter increases in the order of the intermediate portion 88m and the pulley mounting portion 88d. The bearing holding portion 88c has a step portion 88e for holding the bearing, and on the right side thereof has an annular groove portion 88f into which a stopper for holding the bearing is fitted. The movable drive pulley half 64b is fixed to the pulley mounting portion 88d so as to sandwich the flange portion 88g of the pulley mounting portion 88d (see Figs. 4 and 5). The movable drive pulley half 64b is attached to the pulley mounting portion 88d by casting, but may be attached by various joining means such as welding or mechanical joining means.

The outer boss 88 has four holes 88a extending radially. Each of the four holes 88a is a through hole provided in the bearing holding portion 88c of the outer boss 88. The four holes 88a are formed at the same location in the axial direction and are arranged at 90° intervals in the circumferential direction. The outer peripheral ends of the four holes 88a are closed by the inner race 144a of the bearing 144 described above provided between the drive mechanism D and the cam assist mechanism C. In other words, the hole 88a is closed by the inner race 144a of the bearing 144, which defines the bottom of the hole 88a on the radially outer side, and opens only toward the inner boss 80. However, the bottom of the hole 88a is not limited to being closed by the inner race 144a, and may be closed by the outer boss 88 itself, for example. The bearing 144 includes an inner race 144a, an outer race 144b, and a plurality of balls 144c between them.

As shown in Figures 4 and 5, a disc spring 152, which is an elastic member, is disposed between the inner race 144a of the bearing 144 and the ball member 150 in the hole 88a. This disc spring presses the ball member 150 toward the inner boss 80, allowing the ball member 150 to roll more smoothly along the groove 80b of the inner boss 80 as the rolling surface 80f. Note that the elastic member is not limited to the disc spring 152, and a wave washer, for example, may be used instead of the disc spring 152.

Here, FIG. 12 shows an enlarged cross-sectional view of one hole 88a of the outer boss 88 in the cam assist mechanism C. Note that FIG. 12 is a cross-sectional view taken along a virtual plane perpendicular to the axis 20A of the crankshaft 20.

When the cam assist mechanism C rotates together with the crankshaft 20 in the rotation direction R shown in Figures 7, 9, 10 and 12, if the crankshaft 20 rotates faster than before, the rotation of the outer boss 88 is likely to be delayed relative to the inner boss 80. As a result, a force is applied to the ball member 150 from the inner boss 80, and for example, a force F as shown in Figure 12 is applied from the edge portion 80c of the groove portion 80b of the inner boss 80. The force F can be divided into a normal load F1, a tangential load F2 perpendicular to the normal load F1, and a circumferential force F3. The circumferential force F3 is applied from the ball member 150 to the outer boss 88, and the reaction force of the circumferential force F3 encourages the ball member 150 to move along the rolling surface 80f of the groove portion 80b of the inner boss 80, which encourages the outer boss 88 to move together with the ball member 150. As the groove 80b of the inner boss 80 is helical as described above, the direction of this movement is opposite to the direction of rotation R as is clear from Figures 7 and 8, and is also in the axial direction, in this case the direction to the left in the axial direction. Note that this direction to the left in the axial direction is the direction toward the fixed drive pulley half 64a.

On the other hand, when the rotation of the crankshaft 20 becomes faster than before, the control device, i.e., the ECU 170 described later, controls the operation of the motor 120 to move the movable driving pulley half 64b closer to the fixed driving pulley half 64a based on the input from the sensor that detects the rotation of the crankshaft 20, i.e., the crank angle sensor in this case, the engine speed sensor 176 described later. This movement of the movable driving pulley half 64b relative to the fixed driving pulley half 64a coincides with the above-mentioned axial direction in which the movement of the outer boss 88 relative to the inner boss 80 is promoted. Therefore, the cam assist mechanism C acts to assist the axial movement of the movable driving pulley half 64b relative to the fixed driving pulley half 64a by the motor 120. In other words, the cam assist mechanism C can assist the axial movement of the movable driving pulley half 64b, which is integral with the outer boss 88, by the rotational movement of the crankshaft 20.

This also occurs in the opposite direction when the rotation of the crankshaft 20 becomes slower than before. When the cam assist mechanism C rotates together with the crankshaft 20 in the rotation direction R, if the rotation of the crankshaft 20 becomes slower than before, the rotation of the inner boss 80 is likely to be delayed relative to the outer boss 88. As a result, a force is applied to the ball member 150 from the inner boss 80, and the ball member 150 is encouraged to move along the rolling surface 80f of the groove portion 80b of the inner boss 80, which encourages the outer boss 88 to move together with the ball member 150. The direction of movement at this time is the direction of the rotation direction R as clear from Figures 7 and 8, since the groove portion 80b of the inner boss 80 is spiral as described above, and is also the axial direction, in this case the direction to the right in the axial direction. Note that this axial right direction is the direction away from the fixed drive pulley half 64a. When the rotation of the crankshaft 20 becomes slower than before in this way, the ECU 170 controls the operation of the motor 120 to move the movable drive pulley half 64b away from the fixed drive pulley half 64a based on the input from the sensor that detects the rotation of the crankshaft 20, i.e., the engine rotation speed sensor 176. This movement of the movable drive pulley half 64b relative to the fixed drive pulley half 64a coincides with the above-mentioned axial direction in which the movement of the outer boss 88 relative to the inner boss 80 is urged, so the cam assist mechanism C acts to assist the axial movement of the movable drive pulley half 64b relative to the fixed drive pulley half 64a by the motor 120.

Therefore, the output of the variable speed drive mechanism D that moves the movable drive pulley half 64b can be reduced compared to when the cam assist mechanism C is not provided. In other words, the movable drive pulley half 64b can be moved with less output from the motor 120. This allows the motor 120 of the variable speed drive mechanism D to be made smaller.

In order to more effectively generate such an assist in the cam assist mechanism C, it is advisable to make the radial thickness 88t of the outer boss 88 equal to or greater than the radius of the ball member 150, and to provide the ball member 150 in the hole 88a with less gaps. Also, the radius of curvature of the rolling surface 80f of each groove 80b is enlarged by 0.1 to 0.7 mm from the radius of curvature of the ball member 150, but by reducing the outer diameter of the inner boss 80, i.e., by reducing the radial thickness 80t, and for example, by setting the depth 80d of the groove 80b of the inner boss 80 to a range of 20% to 45% of the diameter of the ball member 150, the normal load F1 can be reduced and the clearance between the ball member 150 and the rolling surface 80f can be suppressed, thereby improving the toughness against the generation of the hitting sound.

In addition, since the cam assist mechanism C is of the ball cam type, the above-mentioned assist capacity, i.e., the assist thrust, can be easily adjusted by changing the number of ball members 150 or the angle of the rolling surface. Here, FIG. 13 shows a simple diagram of the relationship between the groove portion 80b and the axis 20A in the inner boss 80 as viewed from the arrow XIII in FIG. 7. In FIG. 13, the direction of the groove portion 80b, i.e., the rolling surface 80f, is shown diagrammatically by a line. In FIG. 13, the inclination angle θ of the groove portion 80b with respect to the axis 20A corresponds to the rolling surface angle. By changing the angle θ of this rolling surface, the above-mentioned assist capacity can be changed.

Figure 14 shows a cross-sectional view of the right case 122a of the unit case 122 and its surroundings as seen from the front of the vehicle, and Figure 15 shows a cross-sectional view from behind it. Figure 16 shows the left side of the right case 122a of the unit case 122 as seen from the direction of the axis 20A. As shown in Figures 14 and 15, multiple stopper portions 122s are spaced apart in the circumferential direction on the inner surface of the right case 122a. Here, four stopper portions 122s are arranged at 90° intervals (see Figure 16). However, the number of stopper portions 122s is not limited to four, and it is preferable for there to be at least one.

As shown in Figs. 14 and 15, the right case 122a of the unit case 122 is provided with an extension pipe 154 that extends axially outward, i.e., to the right, and extends toward the front part 12a of the transmission case 12. The extension pipe 154 is provided so that a hole 154h that communicates the inside and outside of the unit case 122 extends to the outside of the case 122. As shown in Fig. 16, the extension pipe 154 is positioned at the vertical upper part of the right case 122a in the motorcycle 1 of Fig. 1. This allows air to flow in and out of the unit case 122 and the power unit P in an optimal manner, which can reduce the pumping load of the motor 120 when the volume of the unit case 122 increases or decreases due to a gear shift, and can suppress condensation in the unit case 122. In addition, the air can flow in and out of the unit case 122 to optimally cool the gear shift drive mechanism D and the like.

A cover portion 156 is provided on the inner surface of the front portion 12a of the transmission case 12 so as to hang down from above to below, partially covering the outer entrance 154a of the extension pipe portion 154, in order to prevent water, oil, etc. from entering the unit case 122 through the extension pipe portion 154. The cover portion 156 is plate-shaped, but is curved along the extension pipe portion 154. In the belt chamber 14 in the transmission case cover 16, the cooling air flows vertically from below to the rear around the crankshaft 20, then vertically upward, and also flows in the same direction along the V-belt 90, as shown in FIG. 2. Therefore, the cover portion 156 is positioned behind the outer entrance 154a of the extension pipe portion 154. Therefore, when the cooling air approaches the outer inlet 154a of the extension pipe section 154, its flow is blocked by the cover section 156 and it passes through a labyrinth-shaped flow path formed around the cover section 156, thereby preventing the active intrusion of fluids such as water and oil from the outer inlet 154a of the extension pipe section 154.

In addition, a drain tube 160, which is a member for draining water, is provided in a hole, i.e., a drain hole 160h, formed in the vertical lower portion of the unit case 122. In particular, a hole 160h that connects the inside and outside of the unit case 122 is formed in the lowest portion of the unit case 122, and the drain tube 160 is provided in the hole 160h. As shown in the cross-sectional view of FIG. 17, the hole 160h is formed in the mating surface between the right case 122a and the left case 122b of the unit case 122, forming a labyrinth structure 160L. The drain tube 160 is made of resin, and the base end 160a is approximately cylindrical and the tip 160b is flattened. In other words, the drain tube 160 functions as a member for draining water that allows water to flow out of the unit case 122 but prevents water from flowing into the unit case 122 through the drain tube 160. Therefore, even if water gets into the unit case 122, the volume change inside the unit case 122 caused by the gear shift can cause the water to flow out of the unit case 122 through the drain tube 160, but it will not flow back in through the tip 160b of the drain tube 160.

The speed change drive mechanism D and cam assist mechanism C integrated with the unit case 122 configured as above are formed with dimensions such that the hole of the inner boss 80 and the like fit exactly onto the crankshaft 20, and are attached as follows. First, the left end of the crankshaft 20 is inserted into the shaft through hole 122i of the right case 122a of the unit case 122, and then the crankshaft 20 is further inserted while rotating the screw member 134 into the female thread portion 142d of the movable holder 142, thereby attaching the speed change drive mechanism D and cam assist mechanism C integrated with the unit case 122 to the front part 12a of the transmission case 12. The unit case 122 is then fixed to the transmission case 12 with the bolt 158. In this way, the speed change drive mechanism D and cam assist mechanism C have excellent mounting properties. The wall that defines the shaft through hole 122i of the right case 122a is fitted, via a seal member, to the outer peripheral surface of the cylindrical portion 12c that extends axially to the left in the front portion 12a of the transmission case 12 that extends around the crankshaft 20.

According to the belt-type continuously variable transmission 10 described above, the speed change drive mechanism D of the belt-type continuously variable transmission 10 includes a screw member 134 that is rotated by the rotation of the motor 120, extends in the axial direction, and is not movable in the axial direction (is not movable in the axial direction), and a movable holder 142 that has a female threaded portion 142d into which the screw member 134 is screwed and is movable in the axial direction together with the movable drive pulley half 64b. With this configuration, the movable holder 142 can be directly driven by the screw member 134, and the drive position at which the movable holder 142 is driven by the screw member 134 can be brought closer to the load position on the belt 90 in the drive pulley 64 (for example, the position of the V-belt 90 shown in Figures 4 and 5) in the radial direction centered on the crankshaft 20. Therefore, it is possible to suppress the inclination of the movable drive pulley half 64b, and to reduce the radial size of the speed change drive mechanism D, thereby enabling the belt-type continuously variable transmission 10 to be made smaller. This allows greater freedom in designing the belt-type continuously variable transmission 10.

In particular, the screw member 134 is positioned closer to the crankshaft 20 than the outer periphery 64o of the movable drive pulley half 64b (see Figures 3 to 5). This makes it possible to more effectively suppress the movable drive pulley half 64b from falling over and reduce the radial size of the speed change drive mechanism D. Note that the outer periphery 64o of the movable drive pulley half 64b is, for example, the outer periphery of the movable drive pulley half 64b.

The speed change drive mechanism D is provided with a unit case 122 that houses the motor 120 and is provided with a reduction mechanism 124 to which the driving force is transmitted by the motor 120, and is provided therein, and the screw member 134 is inserted into a wall portion (case wall portion) 122g of the case 122 that extends in the radial direction of the unit case 122. A first bearing, a bearing 136, and a second bearing, a bearing 138, are provided around the screw member 134 so as to sandwich the wall portion 122g. The bearing 136 is a rolling bearing and is configured to be able to receive radial loads and axial loads, and the bearing 138 is a thrust roller bearing and is configured to be able to receive axial loads. Therefore, the radial load and axial load generated in the screw member 134 can be firmly received. Therefore, by thinning the unit case 122, etc., it is possible to further reduce the size and weight of the belt-type continuously variable transmission 10.

The screw member 134 also has a flange portion 134c extending in the radial direction, and the bearings 136, 138 are sandwiched between the flange portion 134c on the movable drive pulley half 64b side of the wall portion 122g of the unit case 122 and a nut 140, which is a fastening member that is located on the opposite side of the wall portion 122g to the flange portion 134c and is screwed into the screw member 134. This configuration can improve the toughness of the screw member 134 against removal.

In addition, the speed change drive mechanism D uses the outer peripheral surface 142c of the movable holder 142 as a sealing surface between the left case 122b of the unit case 122, and a cap member 148 is provided on the movable drive pulley half 64b side of the female thread portion 142d. With this configuration, compared to when a sealing member is provided on the screw shaft, i.e., the axis of the screw member 134, it is possible to shorten the axial extension of the belt-type continuously variable transmission 10 and also reduce the protrusion of the entire unit including the speed change drive mechanism D.

A hole 154h is also formed in the vertical upper part of the unit case 122, connecting the inside and outside of the case 122. This makes it possible to take in air into the case 122 while effectively preventing the intrusion of water and other substances into the inside of the unit case 122. Note that the hole 154h is provided in a position in the axial direction farther from the movable drive pulley half 64b than the movable holder, that is, in this case, it is provided on the back side of the unit case 122. In this way, the hole 154h is provided on the internal combustion engine E side of the unit case 122. This makes it possible to prevent dust and water from entering the unit case 122 through the hole 154h.

Then, an extension pipe section 154 is provided so as to extend the hole 154h to the outside of the unit case 122, and a cover section 156 is provided so as to partially cover the outer inlet 154a of the extension pipe section 154. Therefore, a labyrinth-shaped flow path can be formed around the cover section 156 which partially covers the outer inlet 154a of the extension pipe section 154, and therefore it is possible to actively prevent fluids such as water and oil from entering the unit case 122 from the outer inlet 154a of the extension pipe section 154.

A drain hole 160h is formed in the lower vertical portion of the unit case 122, and a drain tube 160 is provided in the drain hole 160h as a water draining member. The drain tube 160 has the above-mentioned configuration. Therefore, even if water gets into the unit case 122, the drainage properties of the unit case 122 can be ensured.

The belt-type continuously variable transmission 10 further includes a cam assist mechanism C that converts the rotational motion of the crankshaft into axial motion of the crankshaft 20 so as to assist the axial movement of the movable drive pulley half 64b by the speed change drive mechanism D. This allows the axial movement of the movable drive pulley half 64b by the speed change drive mechanism D to be favorably assisted.

The cam assist mechanism C is of the ball cam type and includes an inner boss 80 that is arranged to be rotatable integrally with the crankshaft 20, an outer boss 88 that is movable axially along the outer circumferential surface 80a of the inner boss 80 together with the movable drive pulley half 64b, and at least one ball member that is arranged to be associated with the inner boss 80 and the outer boss 88. With this configuration, the rotational motion of the crankshaft 20 can be suitably converted into axial motion of the crankshaft 20.

The rolling surface 80f of the ball member 150 is formed on the outer peripheral surface 80a of the inner boss 80, and the ball member 150 is disposed in the hole 88a of the outer boss 88, specifically in this case in the through hole. This allows the number of components of the cam assist mechanism C to be reduced, and also makes it possible to manufacture or process the cam assist mechanism C at low cost.

The bottom of the hole 88a is defined by the inner race 144a of the bearing 144, which is held by the holding portion of the speed change drive mechanism D and the holding portion of the assist mechanism C. This configuration makes it possible to prevent an increase in the number of parts in the cam assist mechanism C, and also makes it easier to form the hole 88a in the outer boss 88.

The disc spring 152 is provided as a pressing member, i.e., an elastic member, as described above to press the ball member 150 against the inner boss 80 (see Figures 4, 5, and 12). This reduces the radial gap between the ball member 150 and the inner boss 80, thereby suppressing the impact noise caused by the ball member 150 hitting the inner boss 80, etc.

Furthermore, the cam assist mechanism C is disposed between the variable speed drive mechanism D and the movable drive pulley half body 64b. Therefore, the cam assist mechanism C can more effectively assist the transmission of the drive force from the variable speed drive mechanism D to the movable drive pulley half body 64b.

When the movable driving pulley half 64b is moved away from the fixed driving pulley half 64a, a stopper portion 122s that restricts the axial movement of the movable driving pulley half 64b to the right is provided on the inner surface of the right case 122a of the unit case 122. The movable holder 142 is formed so that the axial protrusion 142p on the outer periphery of the movable holder 142 can abut against this stopper portion 122s (see FIG. 4). On the other hand, when the movable driving pulley half 64b is moved closer to the fixed driving pulley half 64a, the left axial end portion 64e of the face surface of the movable driving pulley half 64b can abut against the right axial end portion 64d of the face surface of the fixed driving pulley half 64a so as to restrict the axial movement of the movable driving pulley half 64b to the left (see FIG. 5).

Now, in the belt-type continuously variable transmission 10 of the above embodiment, the motor 120 of the transmission drive mechanism D is driven forward and backward to move the movable holder 142 axially, so that the outer boss 88 of the cam assist mechanism C moves relative to the inner boss 80, and as shown by the solid and dashed lines in FIG. 3 and as shown in FIGS. 4 and 5, the movable drive pulley half 64b can approach or move away from the fixed drive pulley half 64a, thereby changing the winding diameter of the V-belt 90 wound between the opposing tapered surfaces of the two drive pulley halves 64a and 64b, thereby performing continuously variable speed change. The control of this motor 120 will be further explained below. However, in this embodiment, the motor 120 is a DC motor.

A block diagram of the ECU (electronic control unit) 170 is shown in FIG. 18. In the motorcycle 1, which is a saddle-ride type vehicle, the ECU 170, which is a control device that controls the operation of the internal combustion engine E and the continuously variable transmission 10, has a configuration as a so-called computer. That is, the ECU 170 has a processor (e.g., a CPU) and a memory (e.g., a ROM and a RAM). The control unit 172 of the ECU 170 has a CPU here and executes information processing by a program. The CPU is also called a processor. However, the CPU is not limited to a single processor, and may have a multi-processor configuration. Also, a single CPU connected to a single socket may have a multi-core configuration. At least a part of the processing of each of the above parts may be performed by a processor other than the CPU, for example, a dedicated processor such as a digital signal processor (DSP) or a graphics processing unit (GPU). Also, at least a part of the processing of each of the above parts may be an integrated circuit (IC) or other digital circuit. Also, at least a part of each of the above parts may include an analog circuit. The CPU in the control unit 172 executes computer programs that are executable and deployed in the main memory, providing various functions. The main memory in the control unit 172 stores the computer programs and/or data executed by the CPU. The main memory in the control unit 172 is a dynamic random access memory (DRAM), a static random access memory (SRAM), a read only memory (ROM), etc.

The control unit 172 is connected to the memory unit 174. The memory unit 174 is a so-called external memory unit, and is used as a memory area that supplements the main memory unit of the control unit 172, and stores computer programs and/or data executed by the CPU of the control unit 172. The memory unit 174 is a hard disk drive, a solid state drive (SSD), etc.

The ECU 170 receives output signals, i.e., output values, from various sensors. For example, an engine speed sensor 176 for detecting the rotation speed (i.e., engine speed) Ne of the crankshaft 20 of the internal combustion engine E, a throttle opening sensor 178 for detecting the opening (throttle opening) Th of the throttle valve 42v of the internal combustion engine E corresponding to the engine load, and a vehicle speed sensor 180 for detecting the vehicle speed are connected to the ECU 170. Here, the vehicle speed sensor 180 is a sensor that detects the wheel speed of the rear wheels Wr, which are the driving wheels. The engine speed sensor 176 is an example of a detection device for detecting the rotation speed of the output shaft of the power source, the throttle opening sensor 178 is an example of a detection device for detecting the load of the power source, and the vehicle speed sensor 180 is an example of a detection device for detecting the vehicle speed.

The ECU 170 includes an intake control unit 173a, a fuel injection control unit 173b, and an ignition control unit 173c, each of which is a functional module. These control units 173a, 173b, and 173c are realized by executing computer programs stored in the memory unit 174 or the like. For example, the ECU 170 analyzes the operating state of the internal combustion engine E based on inputs from various sensors such as the engine speed sensor 176, the throttle opening sensor 178, and the vehicle speed sensor 180, and controls the operation of the throttle valve 42v using the intake control unit 173a. The ECU 170 also controls the operation of the fuel injection valve 45 using the fuel injection control unit 173b based on the analyzed operating state of the internal combustion engine E. The ECU 170 also controls the operation of the spark plug 175 facing the combustion chamber using the ignition control unit 173c based on the analyzed operating state of the internal combustion engine E. Furthermore, the ECU 170 controls the operation of the continuously variable transmission 10, i.e., the operation of the motor 120. Figure 18 mainly shows the configuration of the ECU 170 related to the automatic shift control of the continuously variable transmission 10.

As shown in FIG. 18, the ECU 170 includes a motor control unit 182, which is a functional module. The motor control unit 182 is realized by executing a computer program stored in the memory unit 174 or the like. The motor control unit 182 outputs a control signal, a pulse signal in this case, to the driver 184, and the driver 184 supplies the motor 120 with a current amount corresponding to the pulse signal. A current sensor 186 is further provided to detect the current (motor current) supplied to the motor, and this current sensor 186 is also connected to the ECU 170, and a signal from the current sensor 186 is also input to the ECU 170. Here, the current sensor 186 includes a shunt resistor. The current sensor 186 is an example of a detection device for detecting the motor current. Here, the current sensor 186 is provided within the ECU 170, but it may be provided outside the ECU 170.

The motor control unit 182 is a control unit that controls the motor 120 of the variable speed drive mechanism D. By executing a computer program, the motor control unit 182 is provided with an area determination unit 188, a duty control unit 190, a collision determination unit 192, a current control unit 194, a fixed control unit 196, and a feedback (FB) control unit 198, each of which is a functional module.

The region determination unit 188 determines whether the position of the movable driving pulley half 64b of the driving pulley 64 is in a predetermined end region in the axial direction of the movable driving pulley half 64b. Here, in the axial direction, the direction in which the movable driving pulley half 64b moves away from the fixed driving pulley half 64b is the direction in which the speed ratio of the continuously variable transmission 10 increases, and may be referred to as the low direction or first axial direction, and the direction in which the movable driving pulley half 64b approaches the fixed driving pulley half 64b is the direction in which the speed ratio of the continuously variable transmission 10 decreases, and may be referred to as the high direction or second axial direction. The specified end region includes the end region in the direction in which the movable drive pulley half 64b moves away from the fixed drive pulley half 64b, i.e., in the Low direction, that is, the position of the movable drive pulley half 64b when the axial convex portion 142p on the outer periphery of the movable holder 142, which is integrally connected to the movable drive pulley half 64b, abuts against the stopper portion 122s on the inner surface of the right case 122a (Low abutment position) (see Figure 4), and includes a region a specified distance from the Low abutment position in the High direction (Low end region). In addition, the predetermined end region includes the end region in the direction in which the movable driving pulley half 64b approaches the fixed driving pulley half 64b, i.e., the high direction, that is, the position of the movable driving pulley half 64b when the left axial end 64e of the face surface of the movable driving pulley half 64b abuts against the right axial end 64d of the face surface of the fixed driving pulley half 64a (high abutment position) (see FIG. 5), and includes a region (high end region) at a predetermined distance in the low direction from the high abutment position. Therefore, the region determination unit 188 determines whether the position of the movable driving pulley half 64b of the drive pulley 64 is in the low end region or the high end region. In the ECU 170, the relationship between the vehicle speed and the speed ratio of the continuously variable transmission 10, i.e., the so-called CVT ratio, is predefined, and the data is stored in the storage unit 174. In the judgment regarding the low end region, a judgment is made as to whether or not the speed ratio calculated by a predetermined calculation based on the vehicle speed detected based on the input from the vehicle speed sensor 180, that is, the so-called CVT ratio, exceeds a judgment ratio (Low judgment ratio) set as a judgment threshold for the low end region, and when the CVT ratio exceeds the Low judgment ratio, it is judged that the position of the movable drive pulley half 64b is in the Low end region of the predetermined end region. On the other hand, in the judgment regarding the high end region, a judgment is made as to whether or not the speed ratio calculated by a predetermined calculation based on the vehicle speed detected by the vehicle speed sensor 180, that is, the so-called CVT ratio, is less than a judgment ratio (High judgment ratio) set as a judgment threshold for the high end region, and when the CVT ratio is less than the High judgment ratio, it is judged that the position of the movable drive pulley half 64b is in the High end region of the predetermined end region.

In addition, in order to more reliably determine whether the position of the movable driving pulley half 64b of the driving pulley 64 is in the low end region or the high end region, the region determination unit 188 determines whether the difference (absolute value) between the target rotation speed of the output shaft of the internal combustion engine E, which is the power source, i.e., the crankshaft 20, and the actual rotation speed of the crankshaft 20 exceeds a predetermined rotation speed. Since the CVT ratio exceeds the low determination ratio, the predetermined rotation speed, i.e., the low rotation speed, when it is determined that the position of the movable driving pulley half 64b is in the low end region may be the same as or different from the predetermined rotation speed, i.e., the high rotation speed, when it is determined that the position of the movable driving pulley half 64b is in the high end region. Note that, here, the determination of whether the difference (absolute value) between the target rotation speed of the output shaft of the power source and its actual rotation speed exceeds the predetermined rotation speed is performed as part of the determination of whether the position of the movable driving pulley half 64b is in the predetermined end region, but it is also possible not to perform this determination.

As described above, when it is determined that the position of the movable driving pulley half 64b is in the low end region, in the control of the continuously variable transmission 10, the target rotation speed (here, the target engine rotation speed) is set to a fixed rotation speed, that is, a fixed engine rotation speed, which is usually determined by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening. On the other hand, at this time, when the actual engine rotation speed decreases and becomes lower than a predetermined vehicle speed, the centrifugal clutch 100 begins to slip, the clutch enters a clutch stall region, and the actual engine rotation speed (actual engine rotation speed) decreases and becomes lower than the fixed engine rotation speed. This is because the fixed engine rotation speed is set as an engine rotation speed that is sufficiently higher than the actual engine rotation speed when the vehicle speed is lower than the predetermined vehicle speed. Therefore, by comparing the fixed engine rotation speed with the detected actual engine rotation speed, which is the actual rotation speed of the crankshaft 20, when the difference (absolute value) is greater than the low rotation speed, it is determined that the position of the movable driving pulley half 64b of the driving pulley 64 is in the low end region.

On the other hand, when the position of the movable driving pulley half 64b is determined to be in the High end region as described above, in the control of the continuously variable transmission 10, the operation of the motor 120 is controlled so that the actual engine rotation speed follows the target rotation speed (here, the target engine rotation speed) determined by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening. In this state, when the left axial end 64e of the face surface of the movable driving pulley half 64b hits the right axial end 64d of the face surface of the fixed driving pulley half 64a, the actual engine rotation speed increases above the target engine rotation speed, and the difference between them becomes large. Therefore, when the target engine rotation speed is compared with the detected actual engine rotation speed, which is the actual rotation speed of the crankshaft 20, and the difference (absolute value) is larger than the High rotation speed, it is determined that the position of the movable driving pulley half 64b of the driving pulley 64 is in the High end region.

When the position of the movable drive pulley half 64b of the drive pulley 64 is in a predetermined end region in the axial direction of the movable drive pulley half 64b, the duty control unit 190 limits the duty ratio of the control signal, i.e., the pulse signal, from the motor control unit 182 to the driver 184 to a predetermined limit value or less. In particular, when the speed ratio based on the input from the vehicle speed sensor 180, i.e., the so-called CVT ratio, exceeds the Low judgment ratio and it is determined that the position of the movable drive pulley half 64b is in the Low end region, or when the CVT ratio is less than the High judgment ratio and it is determined that the position of the movable drive pulley half 64b is in the High end region, the duty control unit 190 limits the duty ratio of the control signal, i.e., the pulse signal, from the motor control unit 182 to the driver 184 to a predetermined limit value or less. As a result, the duty ratio of the pulse signal is limited to a predetermined limit value or less, so that the axial movement of the movable drive pulley half 64b can be slowed down. This makes it possible to suppress the impact when the axial convex portion 142p on the outer periphery of the movable holder 142, which is integrally connected to the movable drive pulley half 64b, hits the stopper portion 122s on the inner surface of the right case 122a, or the impact when the left axial end portion 64e of the face surface of the movable drive pulley half 64b hits the right axial end portion 64d of the face surface of the fixed drive pulley half 64a. Note that the predetermined limit value when it is determined that the position of the movable drive pulley half 64b is in the Low end region may be the same as or different from the predetermined limit value when it is determined that the position of the movable drive pulley half 64b is in the High end region.

When it is determined that the position of the movable drive pulley half 64b is in the Low end region, the abutment determination unit 192 determines whether the axial convex portion 142p on the outer periphery of the movable holder 142 integrally connected to the movable drive pulley half 64b abuts against the stopper portion 122s on the inner surface of the right case 122a, that is, whether the movable drive pulley half 64b is in an abutment state. When it is determined that the position of the movable drive pulley half 64b is in the High end region, the abutment determination unit 192 determines whether the left axial end 64e of the face surface of the movable drive pulley half 64b abuts against the right axial end 64d of the face surface of the fixed drive pulley half 64a as shown in FIG. In this abutment determination, it is determined whether the magnitude (absolute value) of the motor current (current value) detected based on the input from the current sensor 186 exceeds a predetermined value (hereinafter, the second predetermined value). When the magnitude (absolute value) of the motor current exceeds the second predetermined value, the collision determination unit 192 determines that such a collision has occurred. When a collision has occurred, the movable drive pulley half 64b cannot move any further in that direction, so the driver 184 tries to apply a larger current than before. As a result, the detected current may become excessive, so this change in current is used to determine whether a collision has occurred. In this collision determination, it is preferable to determine that a collision has occurred when the time during which the magnitude of the motor current exceeds the second predetermined value exceeds a predetermined time. Note that the second predetermined value when it is determined that the position of the movable drive pulley half 64b is in the Low end region may be the same as or different from the second predetermined value when it is determined that the position of the movable drive pulley half 64b is in the High end region.

When the collision determination unit 192 determines that a collision has occurred, the current control unit 194 limits the magnitude of the motor current to a predetermined value (hereinafter, the first predetermined value) or less. This makes it possible to prevent the continuous current of the motor current flowing to the motor 120 from becoming too high. Therefore, for example, when the movable drive pulley half 64b reaches a predetermined end in the axial direction of the movable drive pulley half 64b, it is possible to protect the member that is being abutted. Note that the first predetermined value when it is determined that the position of the movable drive pulley half 64b is in the Low end region may be the same as or different from the first predetermined value when it is determined that the position of the movable drive pulley half 64b is in the High end region.

When the magnitude of the motor current is limited by the current limiting unit 194 to a first predetermined value or less, the fixed control unit 194 controls the motor 120 so that the motor current follows the current of the first predetermined value. Therefore, the gear ratio of the continuously variable transmission 10 is substantially fixed and maintained at a predetermined gear ratio. Specifically, when the magnitude of the motor current is limited when it is determined that the position of the movable drive pulley half 64b is in the Low end region, the fixed control unit 194 controls the operation of the motor 120 so that the gear ratio of the continuously variable transmission 10 is maintained at the gear ratio when the movable drive pulley half 64b is in the Low abutting position as shown in FIG. 4, that is, the fixed gear ratio. On the other hand, when the magnitude of the motor current is limited when it is determined that the position of the movable driving pulley half 64b is in the High end region, the fixed control unit 194 controls the operation of the motor 120 so that the speed ratio of the continuously variable transmission 10 is maintained at the fixed speed ratio, i.e., the speed ratio when the movable driving pulley half 64b is in the High abutting position as shown in Fig. 5. In particular, the control of the operation of the motor 120 by the fixed control unit 194 is executed when the operating state of the continuously variable transmission 10 is in a region where the centrifugal clutch 100 is not completely connected, i.e., a clutch stall region, in other words, when the centrifugal clutch 100 is in a state other than the fully connected state, i.e., in a non-completely connected state, for example, when the vehicle speed is equal to or lower than a predetermined vehicle speed. In other words, when the magnitude of the motor current is limited when it is determined that the position of the movable driving pulley half 64b is in the Low end region as described above, the control of the operation of the motor 120 by the fixed control unit 194 is executed. At this time, the target engine speed is set to an engine speed that is sufficiently higher than the actual engine speed Ne, as shown to the left of the line BL in FIG. 19.

When the centrifugal clutch 100 is in the connected region, that is, when the centrifugal clutch 100 is in a fully connected state, the feedback (FB) control unit 196 feedback controls the operation of the motor 120 so that the actual engine speed Ne follows the target rotation speed (here, the target engine speed) determined by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening. In other words, in the control by this feedback control unit 196, the gear ratio of the continuously variable transmission 10 is varied, and the rotation direction of the motor 120 and the duty ratio of the control signal are calculated according to a predetermined program so as to eliminate the deviation between the target engine rotation speed and the actual engine rotation speed Ne, and the operation of the motor 120 is controlled based on them. In the control by this feedback control unit 196, the deviation between the target engine rotation speed and the actual engine rotation speed Ne is calculated, the rotation direction of the motor 120 is calculated based on this deviation, and the duty ratio of the control signal of the motor 120 is calculated based on this deviation, and this deviation is calculated repeatedly. The throttle opening is an example of an index of the load of the internal combustion engine E, which is the power source.

The program and data for controlling the motor 120 by the motor control unit 182 are stored in, for example, the storage unit 174. FIG. 19 shows mapped data for controlling the motor 120. In FIG. 19, the horizontal axis represents the vehicle speed, the vertical axis represents the engine speed Ne, and the change in the target engine speed (target Ne) according to the throttle opening Th is shown. In FIG. 19, the lines of target Ne (Th0%), target Ne (Th10%), target Ne (Th50%), and target Ne (Th100%) are drawn, and for example, the line of target Ne (Th10%) means the target engine speed when the throttle opening is 10%. In addition, the line BL indicates the boundary where the centrifugal clutch 120 is connected, and corresponds to the Low judgment ratio of the region judgment unit 188. In other words, the lower vehicle speed side of the line BL (the left side of the line BL in FIG. 19) corresponds to the stall region where the centrifugal clutch 120 is not completely connected.

In FIG. 19, as an example, the change in the actual engine speed Ne when the throttle opening is 100% is shown by the line Lne. As shown in FIG. 19, on the lower vehicle speed side of the line BL (to the left of the line BL in FIG. 19), the target engine speed is set sufficiently higher than the actual engine speed Ne. For example, the actual engine speed Ne1 on the line Lne corresponding to the throttle opening of 100% and the vehicle speed S1 is obviously lower than the target Ne1, which is the target engine speed at the throttle opening of 100% and the vehicle speed S1 (Ne1<target Ne1). In this way, on the lower vehicle speed side of the line BL, the target engine speed is set here to be sufficiently higher than the actual speed. Using this difference (for example, Ne1<target Ne1), the above-mentioned region determination unit 188 performs the determination of the low end region. On the lower vehicle speed side of the line BL (to the left of the line BL in FIG. 19), the fixed control unit 194 performs the above-mentioned control.

On the other hand, at higher vehicle speeds than line BL (to the right of line BL in FIG. 19), the feedback control unit 196 executes the above control so that the actual engine speed Ne follows the target engine speed. Therefore, for example, the actual engine speed Ne2 on line Lne corresponding to a throttle opening of 100% and vehicle speed S2 is substantially on the line of target Ne (Th100%).

The fixed control of the gear ratio by the fixed control unit 194 in the region on the lower vehicle speed side of the line BL (to the left of the line BL in FIG. 19) is the above control when the movable drive pulley half 64b is in the low end region, and the fixed control of the gear ratio by the fixed control unit 194 when the movable drive pulley half 64b is in the high end region can be performed in the region on the higher vehicle speed side of the line BL (to the right of the line BL in FIG. 19). For example, the fixed control by the fixed control unit 194 when the movable drive pulley half 64b is in the high end region may be performed to detect the wear state of the belt 90 when the operating time of the continuously variable transmission 10 exceeds a predetermined time or when the traveling distance of the motorcycle exceeds a predetermined traveling distance. This is to more suitably perform the automatic shift control of the continuously variable transmission 10 according to the wear state of the belt 90.

Next, the control of the continuously variable transmission 10 by the motor control unit 182 having the above configuration, i.e., the control method, will be described with reference to the flowchart in Figure 20.

In step S2001, the motor control unit 182 of the ECU 170 determines whether the position of the movable drive pulley half 64b of the drive pulley 64 is in a predetermined end region in the axial direction of the movable drive pulley half 64b. This determination is performed by the region determination unit 188. In this determination, as described above, it is determined whether the position of the movable drive pulley half 64b of the drive pulley 64 is in the Low end region or the High end region. In the determination regarding the Low end region, it is determined whether the gear ratio calculated by performing a predetermined calculation based on the vehicle speed detected based on the input from the vehicle speed sensor 180, that is, the so-called CVT ratio, exceeds the above-mentioned Low determination ratio, and when the CVT ratio exceeds the Low determination ratio, it is determined that the position of the movable drive pulley half 64b is in the Low end region of the predetermined end region. On the other hand, in the judgment regarding the High end region, a judgment is made as to whether or not the gear ratio calculated by a predetermined calculation based on the vehicle speed detected based on the input from the vehicle speed sensor 180, that is, the so-called CVT ratio, is less than the High judgment ratio, and when the CVT ratio is less than the High judgment ratio, it is judged that the position of the movable drive pulley half 64b is in the High end region of the predetermined end region. In this way, by comparing the CVT ratio with the predetermined judgment ratio, it is judged whether or not it is in the predetermined end region. Note that this judgment determines whether the position of the movable drive pulley half 64b is in the Low end region or the High end region, and the threshold value for judgment from step S2003 onwards is set accordingly as described above.

When it is determined that the position of the movable drive pulley half 64b is in either the low end region or the high end region (positive determination in S2001 in FIG. 20), the duty ratio of the control signal from the motor control unit 182 to the driver 184 is limited to a predetermined limit value α or less (S2003 in FIG. 20). As a result, when the duty ratio reaches the predetermined limit value α thereafter, the duty ratio is limited to a predetermined limit value α or less, so that the axial movement of the movable drive pulley half 64b can be slowed down, and therefore the impact of the abutment against the stopper portion 122s, particularly when the position of the pulley half 64b is in the low end region, can be suppressed. Here, when the duty ratio reaches the predetermined limit value α, the duty ratio is limited to and maintained at the predetermined limit value α. On the other hand, when it is not determined that the position of the movable drive pulley half 64b is in either the low end region or the high end region (negative determination in S2001 in FIG. 20), the restriction on the duty ratio of the control signal from the motor control unit 182 to the driver 184 to be equal to or less than the predetermined limit value α is lifted (S2004 in FIG. 20).

Then, in step S2005, which is the next step after step S003, it is determined whether the difference between the target rotation speed of the output shaft of the internal combustion engine E, i.e., the crankshaft 20, i.e., the target engine rotation speed, and the actual rotation speed of the crankshaft 20, i.e., the actual engine rotation speed Ne, i.e., the magnitude of the Ne deviation (|Ne deviation|), is greater than a predetermined rotation speed β. The target engine rotation speed is calculated by performing an operation based on the throttle opening Th detected based on the input from the throttle opening sensor 178 and the vehicle speed detected based on the input from the vehicle speed sensor 180, based on the mapped data as shown in FIG. 19. The actual engine rotation speed Ne is detected based on the input from the engine rotation speed sensor 176. Then, the difference between the target engine rotation speed and the actual engine rotation speed Ne, i.e., the Ne deviation, is calculated, and the magnitude of the Ne deviation is compared with the predetermined rotation speed β, which is a predetermined value. When the magnitude of the Ne deviation is greater than the predetermined rotation speed β, a positive determination is made in step S2003. If the determination in step S2005 is negative, the process does not proceed to step S2004 for removing the duty ratio restriction, but rather to step S2015, which will be described later.

When it is determined that the magnitude of the Ne deviation (|Ne deviation|) exceeds the predetermined rotation speed β (positive determination in S2005 in FIG. 20), it is determined whether the movable driving pulley half 64b is in an abutting state (S2007, S2008 in FIG. 20). That is, it is determined here whether the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b. Step S2007 is a determination of whether the magnitude of the motor current exceeds a second predetermined value γ. Then, when it is determined positive in step S2007 that the magnitude of the motor current exceeds the second predetermined value γ, it is determined in the next step S2008 whether the time by which the motor current has exceeded the predetermined time. That is, when a positive determination is made in step S2007, the timer means of the ECU 170 starts time measurement, and it is determined in step S2008 whether the measured time has exceeded the predetermined time. When a negative determination is made in step S2008 that the measured time has not exceeded the predetermined time, the process returns to step S2001. When the measured time exceeds the predetermined time in step S2008, an affirmative determination is made, which means that the movable drive pulley half 64b is determined to be in an abutting state. This determination (S2007, S2008 in FIG. 20) corresponds to a determination of whether the movable pulley half 64b has reached a predetermined end, and is performed by the abutment determination unit 192.

When it is determined that the movable drive pulley half 64b is in an abutting state (positive determinations in S2007 and S2008 in FIG. 20), the process proceeds to step S2009, where abutment determination flag indicating that an abutment determination has been made is set to ON. As a result, the process proceeds to step S2010, where the magnitude of the motor current is limited to a first predetermined value or less. Here, the magnitude of the motor current is limited to the first predetermined value. This current limit is executed by the current limiting unit 194. Then, the process proceeds to step S2011, where the setting is made so that the fixed control is executed by the fixed control unit 194. As a result, the motor 120 is controlled so that the motor current follows the first predetermined value. Thus, it is possible to prevent an excessive current from being continuously supplied to the motor 120, and it is possible to maintain the movable drive pulley half 64b in an abutting state (see FIG. 4 or FIG. 5). Note that the determination flag is provided here and can be used when processing other determinations, etc., by the ECU 170, but it is not necessary to provide it.

On the other hand, if a negative judgment is made in any of steps S2001, S2005, and S2007, the process proceeds to step S2013, where the collision judgment is released and the collision judgment flag is set to the OFF state. If the collision judgment flag was in the OFF state up until that point, it is simply passed and the OFF state is maintained. Then, in step S2015, the current limit is released. This current limit is released when the magnitude of the motor current was limited to a first predetermined value or less in step S2010 up until that point, and is simply passed otherwise. Then, the process proceeds to step S2017, where feedback control (FB control) is set by the feedback control unit 196. As described above, in the feedback control, the centrifugal clutch 100 is connected, and the operation of the motor 120 is controlled so that the actual engine rotation speed Ne follows the target rotation speed (here, the target engine rotation speed) that is determined by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening.

Here, based on the timing chart of FIG. 21, the determination of whether the movable drive pulley half 64b is in the low abutment position as shown in FIG. 4 will be further explained. FIG. 21 shows time on the horizontal axis, and indicates the change in the actual engine rotation speed Ne (represented as "actual Ne" in the figure) relative to the target engine rotation speed (target Ne) indicated by the dashed line, as well as the change in the position of the movable drive pulley half 64b (pulley position in FIG. 21), the change in the duty ratio of the control signal from the motor control unit 182, and the change in the motor current of the motor 120. Note that "H" and "L" in FIG. 21 for the pulley position indicate the high and low directions, respectively. Also, the "+" direction of the motor current corresponds to the rotation direction of the motor 120 for moving the movable drive pulley half 64b in the low direction.

When the actual engine speed reaches the stall region where the centrifugal clutch 100 slips during the above-mentioned feedback control, that is, when it reaches the line BL from the region to the right of the line BL in the graph of FIG. 19 (timing "t11" in FIG. 21), the actual engine speed Ne starts to decrease away from the target engine speed. At this time, if the gear ratio calculated based on the vehicle speed detected based on the input from the vehicle speed sensor 180, i.e., the CVT ratio, exceeds the Low judgment ratio, it is judged that the position of the movable drive pulley half 64b is in the Low end region of the predetermined end region (timing "t21" in FIG. 22, positive judgment in S2001 in FIG. 20). As a result, the duty ratio of the control signal from the motor control unit 182 to the driver 184 is limited to a predetermined limit value α or less (S2003 in FIG. 20). Then, when the magnitude of the Ne deviation (|Ne deviation|) becomes greater than the predetermined rotation speed β (timing t12 in FIG. 21), it is determined with greater certainty that the position of the movable drive pulley half 64b is in the low end region (positive determination in S2005 in FIG. 20).

At this time, since the target engine speed is set to a fixed engine speed, the motor control unit 182 increases the duty ratio of the control signal so that the actual engine speed follows the target engine speed. As a result, when the duty ratio reaches the predetermined limit value α (timing "t13" in FIG. 21), since the duty ratio is already limited to or below the predetermined limit value α (S2003 in FIG. 20), the duty ratio is maintained below the predetermined limit value α, and is essentially maintained at the predetermined limit value α here. Then, the motor current gradually decreases as the load is reduced, but when the movable drive pulley half 64b reaches the low abutment position and enters an abutment state (timing "t14" in FIG. 21), the motor current begins to increase. As a result, when the magnitude of the detected motor current reaches the second predetermined value γ (timing "t15" in FIG. 21, positive judgment in step S2007) and the time during which the motor current reaches the second predetermined value γ (time between t15 and t16) has elapsed a predetermined time (timing "t16" in FIG. 21, positive judgment in S2008), it is determined that the movable drive pulley half 64b is in an abutting state. Therefore, the abutment judgment flag indicating that an abutment judgment has been made is set to the ON state (S2009 in FIG. 20).

As a result, since the movable drive pulley half 64b is in an abutting state, the magnitude of the motor current is limited to a first predetermined value (current limit value) that is lower than the second predetermined value γ described above (S2010 in FIG. 20). This current limiting is performed by the current limiting unit 194. As a result, the setting is made so that fixed control is performed (S2011). As a result, the motor 120 is controlled so that the motor current follows the first predetermined value.

Next, based on the timing chart of FIG. 22, the determination that the movable drive pulley half 64b is in the High abutment position as shown in FIG. 5 will be further described. In FIG. 22, as in FIG. 21, the horizontal axis represents time, and shows the change in actual engine rotation speed Ne (referred to as "actual Ne" in the figure) relative to the target engine rotation speed (target Ne) shown by the dashed line, as well as the change in the position (pulley position) of the movable drive pulley half 64b, the change in the duty ratio of the control signal from the motor control unit 182, and the change in the motor current of the motor 120. Note that the "-" direction of the motor current corresponds to the rotation direction of the motor 120 for moving the movable drive pulley half 64b in the High direction.

During the above-mentioned feedback control, when the speed ratio calculated based on the vehicle speed detected based on the input from the vehicle speed sensor 180, i.e., the CVT ratio, becomes less than the High judgment ratio, it is judged that the position of the movable driving pulley half 64b is in the High end region of the predetermined end region (timing "t21" in FIG. 22, positive judgment in S2001 in FIG. 20). As a result, the duty ratio of the control signal from the motor control unit 182 to the driver 184 is limited to a predetermined limit value α or less (S2003 in FIG. 20). Then, when the movable driving pulley half 64b reaches the High abutment position and enters an abutment state (timing "t22" in FIG. 22), the actual engine rotation speed Ne begins to increase so as to move away from the target engine rotation speed. Then, when the magnitude of the Ne deviation (|Ne deviation|) becomes greater than the predetermined rotation speed β (timing "t23" in FIG. 22), it is more reliably judged that the position of the movable driving pulley half 64b is in the High end region (positive judgment in S2005 in FIG. 20).

At this time, the motor control unit 182 increases the duty ratio of the control signal so that the actual engine speed follows the target engine speed. As a result, when the duty ratio reaches the predetermined limit value α (timing "t24" in FIG. 21), since the duty ratio has already been limited to or below the predetermined limit value α (S2003 in FIG. 20), the duty ratio is maintained below the predetermined limit value α, and is essentially maintained at the predetermined limit value α here. Then, the magnitude of the motor current also starts to increase in the same manner as the duty ratio. As a result, when the magnitude of the detected motor current reaches the second predetermined value γ (timing "t25" in FIG. 21, positive judgment in step S2007) and the time during which the motor current has reached the second predetermined value γ has elapsed (time between t25 and t26) (timing "t26" in FIG. 21, positive judgment in S2008), it is judged that the movable drive pulley half 64b is in abutment. Therefore, abutment judgment flag indicating that abutment judgment has been made is set to ON (S2009 in FIG. 20).

As a result, since the movable drive pulley half 64b is in an abutting state, the magnitude of the motor current is limited to a first predetermined value (current limit value) that is lower than the second predetermined value γ described above (S2010 in FIG. 20). This current limit is performed by the current limiting unit 194. As a result, the setting is made so that fixed control is performed (S2011 in FIG. 20). As a result, the motor 120 is controlled so that the motor current follows the first predetermined value.

When the position of the movable drive pulley half 64b is in the high end region, the deviation of the actual engine rotation speed Ne from the target engine rotation speed occurs only after the movable drive pulley half 64b is in an abutting state. Therefore, when the position of the movable drive pulley half 64b is in the high end region, the increase in the magnitude of the current of the motor 120 occurs along with an increase in the |Ne deviation|, so the abutment determination may be performed earlier than when the position of the movable drive pulley half 64b is in the low end region. For example, in the flowchart of FIG. 20, step S2005 may be omitted or moved between steps S2007 and S2008. This also applies to the limitation of the magnitude of the current (S2010 in FIG. 20).

Next, based on the timing chart of FIG. 23, the transition from when the operating state of the centrifugal clutch 100 is in the stall region, i.e., when it is in the fixed control region, to the feedback control region to the right of line BL in FIG. 19 will be described. In FIG. 23, like FIG. 21, the horizontal axis represents time, and the change in the actual engine speed Ne (referred to as "actual Ne" in the figure) is shown relative to the target engine speed (target Ne) shown by the dashed line, as well as the change in the position (pulley position) of the movable drive pulley half 64b, the change in the duty ratio of the control signal from the motor control unit 182, and the change in the motor current of the motor 120. FIG. 23 also shows the change in the throttle opening Th and the ON (S2010 in FIG. 20) and OFF (S2015 in FIG. 20) of the current limiting.

As shown in FIG. 4, when the movable driving pulley half 64b is in the low abutment position, the actual engine speed Ne is far from the fixed engine speed, which is the target engine speed, and the motor current is limited as described above, so the motor current is approximately constant at its first predetermined value (current limit value), and the duty ratio of the control signal is also approximately constant. In this state, when the throttle opening increases, the fixed engine speed also changes according to the change in the throttle opening, as shown in FIG. 19. Then, when the engine speed gets on the line BL as described in FIG. 19, the engine speed Ne approaches the target engine speed, and the centrifugal clutch is engaged (timing "t31" in FIG. 23). Then, when the magnitude of the Ne deviation (|Ne deviation|) becomes equal to or less than the predetermined rotation speed β (timing "t32" in FIG. 23, negative judgment in S2005 in FIG. 20), the current limit is released (S2015 in FIG. 20). This allows the above-mentioned feedback control to be performed (S2017 in FIG. 20).

In this way, in the control of the continuously variable transmission 10, it is possible to appropriately determine whether the movable drive pulley half 64b is in the low abutment position (see FIG. 4) and whether the movable drive pulley half 64b is in the high abutment position (see FIG. 5) and has reached that position, without providing a sensor for detecting the position of the movable drive pulley half 64b on the drive pulley 64 or the movable drive pulley half 64b, by detecting the current of the motor 120, i.e., the motor current.

In addition, a centrifugal clutch 100 is provided between the driven pulley 94 and driven shaft 92 of the continuously variable transmission. When the centrifugal clutch 100 is in a fully connected state, feedback control, i.e., ratio feedback control, is performed to control the operation of the motor 120 so that the detected actual engine speed follows the target engine speed calculated by performing a predetermined calculation based on the detected vehicle speed and the detected throttle opening. In contrast, when the centrifugal clutch 100 is in an incompletely connected state, which includes slipping of the centrifugal clutch 100, control is performed to limit the motor current as described above, i.e., fixed control.

The following describes the operation and effects of the control of the motor 120 by the ECU 170, which is the control device for the continuously variable transmission 10 described above.

The continuously variable transmission 10 includes a drive pulley 64 to which a driving force is transmitted from the crankshaft 20 of the internal combustion engine E, a driven pulley 94 equipped with a centrifugal clutch 100, and a belt 90 stretched between the drive pulley 64 and the driven pulley 94. The centrifugal clutch 100 rotates together with the driven pulley 94 and is connected when the rotation speed exceeds a predetermined rotation speed to transmit the driving force of the internal combustion engine E to the drive wheel Wr. The ECU 170 of the continuously variable transmission 10 includes a motor control unit 182 that controls a motor 120 that generates a driving force in the axial direction of the movable drive pulley half 64b so as to move the movable drive pulley half 64b relative to the fixed drive pulley half 64a in the drive pulley 64. As described above, when the centrifugal clutch 100 is not fully engaged, the motor control unit 182 controls the motor 120 to maintain the gear ratio of the continuously variable transmission 10 at a fixed gear ratio (S2011 in FIG. 20), and when the centrifugal clutch 100 is fully engaged, feedback controls the operation of the motor 120 based on the detected vehicle speed and the detected throttle opening (S2017 in FIG. 20).

According to this configuration, when the centrifugal clutch 100 is not fully connected, that is, when the centrifugal clutch 100 is slipping or disengaged, the motor 120 is controlled to maintain the gear ratio of the continuously variable transmission 10 at a fixed gear ratio. Therefore, when the centrifugal clutch 100 is not fully connected, the motor 120 can be controlled without having to accurately grasp the driving state of the driven pulley 94, for example, its rotational speed, and the gear ratio of the continuously variable transmission 10 can be controlled to a fixed gear ratio. Therefore, for example, it is possible to omit a sensor that detects the rotational speed of the driven pulley 94 from inside the case of the continuously variable transmission 10. In this way, according to the above configuration, it is possible to control the gear ratio to a target ratio while reducing the number of parts in the transmission case. When the centrifugal clutch 100 is fully engaged, the operation of the motor 120 is feedback-controlled so that the actual engine speed follows the target engine speed determined based on the detected vehicle speed and the detected throttle opening. In this case, the feedback control is possible even if there is no sensor inside the transmission case to detect the rotation speed of the driven pulley 94. This is because when the centrifugal clutch 100 is fully engaged, the vehicle speed and the rotation speed of the driven pulley 94 correspond to each other.

When controlling the motor 120 to maintain the gear ratio of the continuously variable transmission 10 at a fixed gear ratio, the motor control unit 182 limits the magnitude of the current of the motor 120 to a first predetermined value α or less (S2010 in FIG. 20) and limits the duty ratio of the control signal to the motor 120 to a predetermined limit value β or less (S2003 in FIG. 20). With this configuration, even if the movable drive pulley half 64b hits, for example, the stopper portion 122s, the duty ratio is limited to a predetermined limit value β or less, so that the speed of movement of the movable drive pulley half 64b can be slowed down, and the collision load at the time of the hit can be suppressed, thereby protecting each component. Furthermore, by limiting the magnitude of the current of the motor 120 to a predetermined value α or less, the continuous current flowing to the motor 120 can be prevented from becoming excessive, thereby protecting the motor 120.

In addition, when the motor 120 is controlled to maintain the speed ratio of the continuously variable transmission 10 at a fixed speed ratio, the movable drive pulley half 64b reaches a predetermined end in the axial direction of the movable drive pulley half 64b. According to this configuration, when the motor 120 is controlled to maintain the speed ratio of the continuously variable transmission 10 at a fixed speed ratio, the movable drive pulley half 64b reaches a predetermined end in the axial direction of the movable drive pulley half 64b, so that the speed ratio of the continuously variable transmission 10 can be controlled to the fixed speed ratio with simpler control.

Furthermore, when the centrifugal clutch 100 is in an incompletely connected state, the motor control unit 182 determines whether the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b based on the current of the motor 120 (S2007, S2008 in FIG. 20), and when it is determined that the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b, controls the operation of the motor 120 so as to maintain the gear ratio of the continuously variable transmission 10 at a fixed gear ratio (S2011 in FIG. 20). According to this configuration, it is determined whether the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b based on the current of the motor 120. Therefore, for example, the arrival of the movable driving pulley half 64b at the predetermined end can be detected without providing a sensor that directly detects the position of the movable driving pulley half 64b. Then, when it is determined that the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b, the motor 120 is controlled to maintain the gear ratio of the continuously variable transmission 10 at a fixed gear ratio. Therefore, in controlling the continuously variable transmission 10, it becomes possible to move the movable driving pulley half 64b over a wide range including the point where the movable driving pulley half 64b reaches the predetermined end, and therefore it becomes possible to further expand the movable range of the movable driving pulley half 64b of the drive pulley 64.

When it is determined that the movable drive pulley half 64b has reached a predetermined end in the axial direction of the movable drive pulley half 64b, the abutment portion on the movable drive pulley half 64b side, i.e., the axial convex portion 142p, abuts against the stopper portion 122s that restricts the axial movement of the movable drive pulley half 64b away from the fixed drive pulley half 64b. This makes it possible to limit the abutment of the movable drive pulley half 64b to the axial convex portion 142 and the stopper portion 122s, and other components can be protected more reliably.

In addition, when the position of the movable drive pulley half 64b is in a predetermined end region in the axial direction of the movable drive pulley half 64b, i.e., the Low end region or the High end region, the motor control unit 182 limits the duty ratio of the control signal of the motor 120 to a predetermined limit value or less (S2003 in FIG. 20), and determines whether the movable drive pulley half 64b has reached a predetermined end in the axial direction of the movable drive pulley half 64b, i.e., the Low abutment position or the High abutment position, based on the current of the motor 120 detected when the duty ratio is limited to the predetermined limit value β or less (S2007, S2008 in FIG. 20). Therefore, when the position of the movable drive pulley half 64b is in the predetermined end region, the duty ratio of the control signal of the motor 120 is limited to a predetermined limit value or less, which makes it possible to protect the movable drive pulley half 64b from abutting. Then, based on the detected current of the motor 120, it is determined whether the movable drive pulley half 64b has reached a predetermined end in the axial direction of the movable drive pulley half 64b. Therefore, it is possible to detect the arrival of the movable drive pulley half 64b at the predetermined end without providing a sensor that directly detects the position of the movable drive pulley half 64b. Therefore, in the automatic shift control of the continuously variable transmission 10, it is possible to move the movable drive pulley half 64b over a wide range including the point where the movable drive pulley half 64b reaches the predetermined end, and therefore it is possible to further expand the movable range of the movable drive pulley half 64b of the drive pulley 64.

In addition, when the magnitude of the difference between the target rotation speed (here, the target engine rotation speed) of the crankshaft 20, which is the output shaft of the internal combustion engine E as the power source, and the actual rotation speed of the crankshaft, here, the actual engine rotation speed Ne, is greater than a predetermined rotation speed β, the motor control unit 182 executes a determination as to whether the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b based on the current of the motor 120 detected at that time (S2005, S2007, S2008 in FIG. 20). When the position of the movable driving pulley half 64b is in the predetermined end region, the magnitude of the difference between the target rotation speed of the crankshaft 20 of the internal combustion engine E and the actual rotation speed of the crankshaft 20 becomes greater than the predetermined rotation speed, so at this time, based on the current of the motor 120 detected, a determination is made as to whether the movable driving pulley half 64b has reached a predetermined end in the axial direction of the movable driving pulley half 64b. This reduces the computational load on the ECU 170 and makes it possible to more effectively determine whether the movable drive pulley half 64b has hit the ground.

When it is determined that the movable drive pulley half 64b has reached a predetermined end in the axial direction of the movable drive pulley half 64b, i.e., the low abutment position or the high abutment position (S2007, S2008 in FIG. 20), the motor control unit 182 further executes limiting the magnitude of the current (motor current) of the motor 120 to a first predetermined value or less, in particular to the first predetermined value. According to this configuration, when the movable drive pulley half 64b has reached a predetermined end in the axial direction of the movable drive pulley half 64b, the magnitude of the current of the motor 120 is limited to the first predetermined value, so that, for example, it is possible to prevent an excessive current from continuing to flow through the motor 120, and therefore it is possible to protect the motor 120 itself.

Furthermore, when the time during which the magnitude of the detected current of the motor 120 reaches a second predetermined value, which is higher than the first predetermined value, exceeds a predetermined time, the motor control unit 182 executes the step of determining that the movable drive pulley half 64b has reached a predetermined end in the axial direction of the movable drive pulley half 64b (S2008 in FIG. 20). With this configuration, it is possible to more accurately determine that the movable drive pulley half 64b has reached the predetermined end.

Although one embodiment of the present invention and its modified examples have been described above, the present invention is not limited to the above-described embodiment, and various other modifications are possible within the scope of the gist of the present invention. For example, the power unit and internal combustion engine of the present invention may be applied not only to motorcycles, but also to a wide range of other types of saddle-type vehicles. For convenience of explanation, the left-right arrangement of the device has been described according to the illustrated embodiment, but is not limited to this, and the left-right arrangement may be reversed.

In the above embodiment, the cam assist mechanism was of the ball cam type, but other types that convert the rotational motion of the output shaft of the power source into axial motion of the output shaft may be adopted. Note that the mechanism (axial slide mechanism) that moves the movable drive pulley half 64b axially relative to the fixed drive pulley half 64a by the operation of the drive mechanism is not limited to the cam assist mechanism C, and may be, for example, a mechanism that simply allows the movable drive pulley half 64b to move axially relative to the fixed drive pulley half 64a by the axial driving force of the drive mechanism D. Also, the power source may be something other than an internal combustion engine.

1...motorcycle, 10...belt-type continuously variable transmission, 20...crankshaft, 64...drive pulley
64a...fixed driving pulley half, 64b...movable driving pulley half, 90...V-belt, 94...driven pulley
94a: fixed driven pulley half, 94b: movable driven pulley half, 120: motor, 130: first reduction gear
132: second reduction gear, 134: screw member, 142: movable holder
170...Electronic control unit (ECU), C...Cam assist mechanism
D... Drive mechanism, E... Internal combustion engine, P... Power unit

Claims (6)

A control device (170) for a belt-type continuously variable transmission (10) including: a drive pulley (64) to which a driving force is transmitted from an output shaft (20) of a power source (E) of a vehicle (1); a driven pulley (94) equipped with a centrifugal clutch (100) which rotates integrally with the driven pulley (94) and is connected to the driven pulley (94) when a predetermined rotation speed is exceeded, thereby transmitting the driving force of the power source (E) to a driving wheel (Wr) of the vehicle (1); and a belt (90) stretched between the drive pulley (64) and the driven pulley (94),
a control unit (182) for controlling a motor (120) that generates a driving force in an axial direction of the movable pulley half (64b) so as to move the movable pulley half (64b) relative to the fixed pulley half (64a) in the drive pulley (64),
The control unit (182)
performing duty control of the motor (120) to limit a duty ratio to a predetermined limit value or less when the position of the movable pulley half (64b) is in a low end region, which is an end region in a low direction where the movable pulley half (64b) is away from the fixed pulley half (64a) in the axial direction, or when the movable pulley half (64b) is in a high end region, which is an end region in a high direction where the movable pulley half (64b) approaches the fixed pulley half (64a) in the axial direction ;
controlling the motor (120) so as to maintain a speed ratio, which is controlled by a position of a movable pulley half (64b) relative to a fixed pulley half (64a) of a drive pulley (64) of the continuously variable transmission (10), at a fixed speed ratio when the centrifugal clutch (100) is in an incompletely connected state;
and when the centrifugal clutch (100) is in a fully engaged state, feedback control of the operation of the motor (120) is performed based on the detected vehicle speed and the detected load of the power source.
A control device (170) for a belt-type continuously variable transmission (10), characterized in that, when controlling the motor (120) to maintain the gear ratio of the continuously variable transmission (10) at the fixed gear ratio, the control unit (182) limits the magnitude of the current of the motor (120) to a predetermined value greater than zero or less, and limits the duty ratio of a control signal to the motor (120) to a predetermined limit value or less. 2. The control device (170) for a belt-type continuously variable transmission (10) according to claim 1, characterized in that, when the motor (120) is controlled to maintain the speed ratio of the continuously variable transmission (10) at a fixed speed ratio, the movable pulley half (64b) reaches a predetermined end in the axial direction of the movable pulley half (64b). The control unit (182)
determining, based on a current of the motor (120), whether or not the movable pulley half (64b) has reached the predetermined end in the axial direction of the movable pulley half (64b) when the centrifugal clutch (100) is in an incompletely connected state;
and when it is determined that the movable pulley half (64b) has reached the predetermined end in the axial direction of the movable pulley half (64b), controlling the motor (120) so as to maintain the gear ratio of the continuously variable transmission (10) at a fixed gear ratio. 4. The control device (170) for a belt-type continuously variable transmission (10) as described in claim 2 or 3, characterized in that when it is determined that the movable pulley half (64b) has reached the predetermined end in the axial direction of the movable pulley half (64b), the abutment portion (142p) on the movable pulley half (64b) abuts against a stopper portion (122s) that restricts movement of the movable pulley half (64b) in the axial direction away from the fixed pulley half (64b). A belt-type continuously variable transmission (10) including a drive pulley (64) to which a driving force is transmitted from an output shaft (20) of a power source (E) of a vehicle (1), a driven pulley (94) equipped with a centrifugal clutch (100) which rotates integrally with the driven pulley (94) and is engaged when a predetermined rotation speed is exceeded to transmit the driving force of the power source (E) to a driving wheel (Wr) of the vehicle (1), and a belt (90) stretched between the drive pulley (64) and the driven pulley (94), comprising: a control method for controlling a motor (120) which generates a driving force in an axial direction of a movable pulley half (64b) so as to move the movable pulley half (64b) relative to a fixed pulley half (64a) in the drive pulley (64),
the motor (120) is duty-controlled to limit a duty ratio to a predetermined limit value or less when the position of the movable pulley half (64b) is in a low end region, which is an end region in a low direction where the movable pulley half (64b) is away from the fixed pulley half (64a) in the axial direction, or when the movable pulley half (64b) is in a high end region, which is an end region in a high direction where the movable pulley half (64b) approaches the fixed pulley half (64a) in the axial direction;
a step of controlling the motor (120) so as to maintain a speed ratio, which is controlled by a position of a movable pulley half (64b) relative to a fixed pulley half (64a) of a drive pulley (64) of the continuously variable transmission (10) at a fixed speed ratio when the centrifugal clutch (100) is in an incompletely connected state, the step of limiting a magnitude of a current of the motor (120) to a predetermined value greater than zero and limiting a duty ratio of a control signal to the motor (120) to a predetermined limit value or less when controlling the motor (120) so as to maintain the speed ratio of the continuously variable transmission (10) at the fixed speed ratio;
and when the centrifugal clutch (100) is in a fully engaged state, feedback controlling the operation of the motor (120) based on the detected vehicle speed and the detected load of the power source. the step of controlling the motor (120) so as to maintain the gear ratio of the continuously variable transmission (10) at a fixed gear ratio when the centrifugal clutch (100) is in an incompletely connected state,
determining whether or not the movable pulley half (64b) has reached a predetermined end in the axial direction of the movable pulley half (64b) based on a current of the motor (120) when the centrifugal clutch (100) is in an incompletely connected state;
and controlling the motor (120) so as to maintain a gear ratio of the continuously variable transmission (10) at a fixed gear ratio when it is determined that the movable pulley half (64b) has reached the predetermined end in the axial direction of the movable pulley half (64b).

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