JP3993966B2 - Power transmission device for small vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power transmission device for a small vehicle that transmits power from an engine to left and right drive wheels via a belt-type continuously variable transmission and a mechanical automatic transmission, and in particular, about one or two people get on the vehicle. The present invention relates to a lubricating structure for a power transmission device suitable for use in a small vehicle having a simple structure.
[0002]
[Prior art]
In recent years, from the viewpoint of reducing exhaust gas and energy consumption, a small vehicle that can be moved by one or two people has been developed and put into practical use.
Such a small vehicle is configured in a self-supporting form such as a four-wheeled vehicle or a three-wheeled vehicle. For example, as described in JP-A-9-286348, a small engine is used as a power source. It is used as a means that can be easily moved with low exhaust gas with low fuel consumption.
[0003]
In such a small vehicle, as described in JP-A-59-227523, JP-A-62-246648, JP-A-63-145854, JP-B-6-56196, etc. The power of the engine is transmitted to the drive wheels by a belt type continuously variable transmission so that it can be operated easily, and the power of the structure is simpler, cheaper and lighter than an automatic transmission using a hydraulic control system. A transmission device is adopted.
Furthermore, in such a small vehicle, a mechanical transmission is used in combination with a belt-type continuously variable transmission, and the engine power is driven with a wide gear ratio by using the belt-type continuously variable transmission and the mechanical transmission. In addition, the transmission ratio of the belt-type continuously variable transmission is suppressed, and the enlargement of the pulley around which the belt is wound is suppressed.
[0004]
[Problems to be solved by the invention]
Here, in a small vehicle using both a belt-type continuously variable transmission and a mechanical automatic transmission as described above, a centrifugal start clutch is connected to the belt-type continuously variable transmission to transmit engine power when the rotational speed increases. On the other hand, it is conceivable to provide a centrifugal transmission clutch that switches the gear that is connected to transmit power when the rotational speed increases to the mechanical automatic transmission from the low-speed gear to the high-speed gear.
That is, when the engine speed increases from the idling state, the engine power is automatically transmitted to the power train by the centrifugal start clutch, and when the engine speed further increases as the vehicle travels, the centrifugal shift clutch The power transmission gear of the automatic transmission can be switched automatically for high speeds to achieve simple operation with a simple structure, while the power transmission mechanism is lightweight and compact, and the intended purpose such as low fuel consumption is achieved. It can be achieved.
[0005]
However, when the centrifugal start clutch and the centrifugal transmission clutch are provided in this way, different performances are required for the respective clutches, and therefore, a configuration for satisfying both these requirements must be adopted.
In other words, the centrifugal start clutch is required to gain frictional force and be able to connect and transmit power with a small slip speed even with a small rotational speed, while the centrifugal shift clutch requires a slip time. Even if the shift shock is reduced by increasing the length, it is required to be small and have sufficient durability.
[0006]
Further, in such a small vehicle, since the engine of the small vehicle has a relatively small displacement and low output in order to realize low fuel consumption and low exhaust gas, the structure of each part of the vehicle such as a vehicle body or a suspension system. Is required to be simple and lightweight. As a measure to satisfy such demands, the power transmission system mechanisms to the left and right drive wheels such as the engine, transmission, and differential mechanism are miniaturized, and these power devices are integrated into a power unit. As a structure in which the power unit is swingably attached to the vehicle body, a vehicle structure in which the power unit is mounted on the vehicle body and the drive wheel is suspended at once is conceivable. From the viewpoint of improving the comfort and reducing the space for swinging the power unit to make the vehicle body structure compact, it is required to make the power transmission device small and light.
[0007]
The present invention has been made in view of the above-described conventional circumstances, achieves the performance required for a centrifugal start clutch and a centrifugal transmission clutch, and uses a mechanical automatic speed gear in combination with a belt type continuously variable transmission. It is an object of the present invention to provide a power transmission device for a small vehicle that can reduce the gear ratio burden on the machine and make the mechanical automatic speed machine simple and small and light.
It is another object of the present invention to provide a power transmission device particularly suitable for a small vehicle having a structure in which a power transmission system from an engine to a differential mechanism is made into a power unit and this is swingably attached to a vehicle body.
Further objects of the present invention will be apparent from the following description.
[0008]
[Means for Solving the Problems]
The present invention is a power transmission device for a small vehicle in which an engine and a mechanical automatic transmission are connected via a belt-type continuously variable transmission. The belt-type continuously variable transmission is connected to the engine when the rotational speed increases. A centrifugal start clutch is provided to transmit power, and a mechanical transmission is provided with a centrifugal shift clutch that connects the gear that transmits power from low speed gears to high speed gears when the rotational speed increases. The transmission is housed in a case in a dry environment and the centrifugal start clutch is operated in a dry environment, while the mechanical automatic transmission is housed in the case together with lubricating oil and the centrifugal transmission clutch is operated in an oil lubrication environment.
Therefore, since the centrifugal start clutch operates in an environment with a high friction coefficient without lubricant, power can be transmitted with a short slip time even at a small rotation speed, while the centrifugal shift clutch is an environment lubricated with lubricant. Therefore, even if the slip time is lengthened in order to reduce the shift shock, the size can be reduced and sufficient durability can be obtained.
[0009]
Further, in the power transmission system for a small vehicle according to the present invention, a centrifugal starting clutch and a centrifugal type transmission clutch disposed coaxially in the power transmission route to reduce the size of the power transmission device, a request for small-sized vehicle Satisfies.
Furthermore, in the power transmission device for a small vehicle according to the present invention, the case for housing the mechanical automatic transmission and the case for housing the belt-type continuously variable transmission are configured as an integral unit separated by a partition wall, Further, a differential mechanism for driving and rotating the engine and the left and right drive wheels is assembled to the unit to form a power transmission system as a power unit, and this power unit is swingably attached to a small vehicle as a suspension mechanism. Therefore, coupled with a power transmission device that is compact and lightweight, the unsprung weight of the suspension system is reduced, the ride comfort is improved, and the space for swinging the power unit is reduced, making the vehicle structure compact. can do.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be specifically described with reference to an embodiment shown in the drawings.
As shown in FIGS. 1 to 4, the small vehicle of this example is a four-wheeled vehicle having two wheels each on a front wheel 1 and a rear wheel 2, and one occupant (driver) is seated in the center. A single seat driving seat 3 is provided.
The basic vehicle structure of this small vehicle is a frame-type vehicle body frame 4 made of a metal pipe material such as aluminum and covered with a resin body cover 5, and further, above the body cover 5. A resin roof panel 6 is arranged to cover the upper part of the seating seat 3 of the occupant to constitute a cabin.
[0011]
Reference numeral 7 in the figure denotes a steering wheel. By applying a steering force from the steering wheel 7 via a steering mechanism (not shown), the front wheel 1 can change its direction so that the traveling direction of the vehicle can be arbitrarily changed. It has become.
Further, reference numeral 8 in FIG. 1 denotes a select lever provided on the side portion of the seat 3. As will be described later, the select lever 8 allows the mechanical two-speed automatic transmission to be selected as advanced or reverse. Yes.
[0012]
As shown in FIGS. 3 to 6, a frame-type swing frame 10 is attached to the rear portion of the vehicle body frame 4 so as to be swingable up and down with its tip as a pivot. A power unit 40 in which a belt type continuously variable transmission having a starting clutch, a centrifugal transmission clutch type two-speed automatic transmission, a differential mechanism and the like are integrated is provided. The rear wheels 2 are respectively attached to the ends of a pair of drive shafts 80 protruding from the differential mechanism of the power unit 40, and the left and right rear wheels 2 are driven by the power from the power unit 40. .
[0013]
As shown in detail in FIGS. 5 and 6, the swing frame 10 has a structure in which a substantially T-shaped main frame 11 and a pair of trailing arms 12 are combined.
The main frame 11 welds a center pipe 14 extending in the vehicle length direction to the center of the main pipe 13 extending in the vehicle width direction, and further, a sub pipe 15 for supporting the power unit 40 between the main pipe 13 and the center pipe 14. It is a structure that is welded over.
[0014]
The main pipe 13 is attached to an axle block 18 that rotatably supports the drive shaft 80 via brackets 17 at both ends thereof, thereby supporting the rear wheel 2 attached to the drive shaft 80.
The center pipe 14 is inserted and supported with a slight margin in a support hole 4b formed in the rear end panel 4a of the vehicle body frame 4 at the front end thereof, thereby allowing the main pipe 13 to swing. The parallel slide movement is restricted. Note that a rubber ring bush 4c is provided in the support hole 4b to suppress wear and noise caused by a twist between the center pipe 14 and the support hole 4b.
[0015]
The trailing arm 12 is attached via a pivot pin 20 to a bracket 19 attached to the vehicle body frame 4 at the base end thereof, and can swing up and down around the pivot pin 20. Further, the trailing arm 12 is attached to the bracket 17 at the tip thereof via a mounting pin 21 and a rubber bushing 22, and swings and displaces around the pin 21 with the axle block 18 (main pipe 13). And the torsional displacement by the bending of the rubber bush 22 is permitted.
[0016]
Between each trailing arm 12 and the vehicle body frame 4, a suspension unit 25 in which a suspension spring and a shock absorber are assembled is provided. These suspension units 25 are connected to a bracket 26 attached to the vehicle body frame 4 and the trailing arm. 12 is pivotally attached to a bracket 27 attached to 12.
That is, the swing frame 10 swings up and down around the pivot pin 20 together with the rear wheel 2 as the vehicle travels, and the left and right sides of the swing frame 10 are deformed by the bending of the rubber bush 22 and the slight rotation around the axis of the center pipe 14. It operates independently and suspended so that a height difference can occur between the rear wheels 2.
[0017]
As shown in detail in FIG. 7, the power unit 40 is rubber-mounted at three points on the swing frame 10. That is, brackets 29 are attached to the center pipe 14 and the sub-pipe 15, rubber plugs 30 are attached to the brackets 29, front end portions (engine parts) of the power units 40 are attached to the rubber plugs 30, and brackets 31 are attached to the main pipe 13. The rubber plug 32 is attached to the bracket 31, the rear end portion (differential portion) of the power unit 40 is attached to the rubber plug 32, and the power unit 40 is elastically supported on the swing frame 10 at three points.
[0018]
Therefore, the power unit 40 swings together with the swing frame 10 to suspend the rear wheel 2, and the power unit 40 is rubber mounted on the swing frame 10, so that engine vibration is transmitted to the vehicle body via the swing frame 10. Further, since the swing frame 10 itself is also supported by the vehicle body via the rubber ring bush 4c and the rubber bush 22, transmission of engine vibration to the vehicle body is further prevented.
[0019]
As shown in detail in FIGS. 8 to 10, the power unit 40 includes an engine 41, an AC generator 42, a belt-type continuously variable transmission 43, a mechanical two-speed automatic transmission 44 having a reverse gear, and a differential mechanism 45. The power output from the engine 41 is shifted by the belt-type continuously variable transmission 43 and the mechanical two-speed automatic transmission 44, and this power is transferred from the differential mechanism 45 to the left and right rear wheels 2. Each is transmitted to the connected drive shaft 80.
[0020]
The engine 41 is a small displacement engine (in this example, a single cylinder of about 50 cc ), and the movement of the piston 47 due to combustion explosion is transmitted to the crankshaft 49 by the connection rod 48, and the engine power is output by the rotation of the crankshaft 49. To do.
An AC generator 42 is connected to one end of the crankshaft 49, and electric power necessary for driving the vehicle is generated by the rotational power of the engine.
[0021]
A drive pulley 50 of a belt type continuously variable transmission 43 is attached to the other end of the crankshaft 49, and a cylindrical first sub-transfer is provided on a first transfer shaft 51 that is supported in parallel with the crankshaft 49. A shaft 51a is rotatably provided coaxially, and a driven pulley 52 is attached to the first sub-transfer shaft 51a. The drive pulley 50 and the driven pulley 51 are wound around an annular belt 53 having a substantially V-shaped cross section. Are connected.
The drive pulley 50 has a fixed plate 50a fixed to the crankshaft 49, and a movable plate 50b that is fitted to the crankshaft 49 with an axial groove and is rotated along with it, but is movable in the axial direction. Further, a holding plate 50c fixed to the crankshaft 49 is provided behind the movable plate 50b, and a centrifugal roller 50d is provided between the movable plate 50b and the holding plate 50c.
[0022]
On the other hand, the driven pulley 52 and a fixed plate 52a fixed to the first sub-transfer shaft 51a and a movable plate provided so as to be able to move in the axial direction while being fitted to the first sub-transfer shaft 51a with a shaft groove. Further, the movable plate 52b is urged toward the fixed plate 52a by a return spring 52c provided on the back surface of the movable plate 52b.
Therefore, when the engine speed (crankshaft speed) is small, the distance between the movable plate 52b and the fixed plate 52a is narrowed by the return spring 52c, and the belt-wrapping diameter of the driven pulley 52 is increased. The distance between the fixed plate 50a and the movable plate 50b is widened by the tension, and the belt winding diameter of the drive pulley 50 is reduced, and the belt transmission reduction ratio from the drive pulley 50 to the driven pulley 51 is increased.
[0023]
As the engine speed increases, the centrifugal roller 50d moves radially outward by centrifugal force and presses the movable plate 50b from behind, and the distance between the movable plate 50b and the fixed plate 50a is reduced, so that the drive pulley The belt wrapping diameter of 50 is increased, the tension of the belt 53 thereby increases the distance between the movable plate 52b and the fixed plate 52a against the return spring 52c, and the belt wrapping diameter of the driven pulley 52 is decreased. The belt transmission reduction ratio from the pulley 50 to the driven pulley 51 is reduced.
That is, according to the belt-type continuously variable transmission 43, the reduction ratio gradually decreases as the engine speed increases, and the rotation speed of the first sub-transfer shaft 51a increases.
[0024]
A shoe plate 54 is fixed to the tip of the first sub-transfer shaft 51a, and a drum 55 is fixed to the tip of the first transfer shaft 51. A centrifugal shoe 56 is movable outwardly on the shoe plate 54. Thus, a centrifugal start clutch 57 is configured between the first transfer shaft 51 and the first sub-transfer shaft 51a.
That is, when the rotational speed of the first sub-transfer shaft 51a is small as in engine idling, the centrifugal shoe 56 is not pressed against the inner peripheral surface of the drum 55, and the rotational power of the first sub-transfer shaft 51a is As the engine speed increases, the centrifugal shoe 56 moves radially outward due to the centrifugal force and presses against the inner peripheral surface of the drum 55, so that the first transfer shaft 51 is moved to the first transfer shaft 51. The engine is connected to the first sub-transfer shaft 51 a and rotated, and engine power is input from the first transfer shaft 51 to the automatic transmission 44.
[0025]
Here, the case structure of the power unit 40 will be described. A space for accommodating the belt-type continuously variable transmission 43 and a space for accommodating the mechanical automatic transmission 44 and the differential mechanism 45 in the main case 58 attached to the engine block with bolts 58a. Are covered with a cover case 59 attached with a bolt 59a, and a space containing the mechanical automatic transmission 44 and the differential mechanism 45 is bolted. The power train mechanism extending from the engine 41 to the differential mechanism 45 is housed in an integral case, which is covered with a cover case 60 attached at 60a.
[0026]
The belt type continuously variable transmission 43 and the centrifugal start clutch 57 associated therewith are housed in a dry environment case space free of lubricating oil, while the mechanical automatic transmission 44 and the differential mechanism 45 described in detail below together with lubricating oil. In this case structure, the space containing the belt-type continuously variable transmission 43 and the space containing the mechanical automatic transmission 44 and the differential mechanism 45 are the main case. 58, the belt-type continuously variable transmission 43 and the centrifugal start clutch 57 associated therewith are guaranteed to operate in a dry environment free of lubricating oil, and the mechanical automatic transmission 44 and the differential The mechanism 45 is guaranteed to operate in a wet environment with lubricating oil.
[0027]
The first transfer shaft 51 passes through the partition wall portion 58b and is rotatably supported by the bearing 58c. Further, the first transfer shaft 51 is rotatably supported by the cover case 60 by the bearing 60b at the tip thereof. The bearing 58c is provided with a seal 58d for preventing the lubricating oil from entering the wet environment space into the dry environment space.
A gear portion 51b is formed in a portion near the bearing 60b of the first transfer shaft 51, and a cylindrical second sub-transfer shaft 51c is coaxially fixed to a portion near the bearing 58c. The gear portion 51b and the second sub-shaft A cylindrical third sub-transfer shaft 51d is coaxially and rotatably provided between the transfer shaft 51c. That is, when the first transfer shaft 51 rotates, the second sub-transfer shaft 51c always rotates together, but the third sub-transfer shaft 51d can rotate relative to each other without such rotation.
[0028]
A shoe plate 61 is fixed to the second sub-transfer shaft 51c, a drum 62 is fixed to the third sub-transfer shaft 51d, and a centrifugal shoe 63 is movably provided on the shoe plate 61. Thus, a centrifugal transmission clutch 64 is formed between the second sub-transfer shaft 51c and the third sub-transfer shaft 51d. Therefore, the centrifugal transmission clutch 64 and the centrifugal start clutch 57 are arranged coaxially on the first transfer shaft 51, and the arrangement of these devices is compact.
[0029]
According to the centrifugal transmission clutch 64, the centrifugal shoe 63 is not in pressure contact with the inner peripheral surface of the drum 62 when the engine speed is relatively small and the first transfer shaft 51 is small. The rotational power of the shaft 51 is not transmitted to the third sub-transfer shaft 51d, but the second sub-transfer shaft 51c rotates to transmit the engine power. On the other hand, when the engine rotation speed further increases and the rotation speed of the first transfer shaft 51 (that is, the second sub-transfer shaft 51c) increases, the centrifugal shoe 63 moves radially outward due to the centrifugal force, and the inside of the drum 62 The third sub-transfer shaft 51d is connected to the second sub-transfer shaft 51c and rotated while being in pressure contact with the circumferential surface, and engine power is transmitted by the third sub-transfer shaft 51d.
[0030]
A gear portion 51e is formed on the third sub-transfer shaft 51d, and a high-speed gear 65a for shifting is always engaged. The gear portion 51b of the first transfer shaft 51 is always meshed with a low speed gear 65b for shifting, and the high speed gear 65a is set to have a reduction ratio smaller than that of the low speed gear 65b.
In the wet environment space of the case, a second transfer shaft 66 is provided in parallel with the first transfer shaft 51, and the second transfer shaft 66 is interposed between the main case 58 and the case cover 60 via bearings at both ends. It is supported rotatably. The high speed gear 65a is coaxially fixed to the second transfer shaft 66, and the low speed gear 65b is coaxially provided on the high speed gear 65a via a one-way clutch bearing 65c.
[0031]
The one-way clutch bearing 65c allows only the overtaking rotation of the low-speed gear 65b by the high-speed gear 65a. If the low-speed gear 65b rotates, the high-speed gear 65a rotates, but the high-speed gear 65b does not rotate. 65a can be rotated.
Therefore, in a state where the engine speed is relatively small and the centrifugal transmission clutch 64 is not connected, the engine power rotates the low speed gear 65b meshed with the gear portion 51b of the first transfer shaft 51 and is rotated by the one-way clutch bearing 65c. The second transfer shaft 66 is rotated via the high speed gear 65a.
[0032]
On the other hand, when the engine speed is further increased and the centrifugal transmission clutch 64 is connected, the engine power rotates the third sub-transfer shaft 51d and the high-speed gear 65a engaged with the gear portion 51e to rotate the second transfer shaft. 66 is rotated directly. In this case, the low-speed gear 65b also rotates in the same manner as described above, but the high-speed gear 65a overtakes the high-speed rotation by the one-way clutch bearing 65c.
That is, when the centrifugal transmission clutch 64 is not connected, the engine power is transmitted with the reduction ratio by the low speed gear 65b, and when the centrifugal transmission clutch 64 is connected, the engine power is transmitted with the reduction ratio by the high speed gear 65a. The automatic transmission can be realized by a simple and compact configuration in which the centrifugal transmission clutch 64 having a simple and compact configuration and two transmission gears 65a and 65b are arranged coaxially via a one-way clutch bearing 65c. ing.
[0033]
Here, the centrifugal transmission clutch 64 is configured to be connected with a certain degree of slippage in such a transmission operation so as to alleviate the transmission shock, but this centrifugal transmission clutch 64 is the same as the differential mechanism 45. Since oil lubrication is carried out in the case space, it has sufficient durability even when a connection operation having such a long sliding time is performed.
On the other hand, the centrifugal start clutch 57 is configured such that the slip time is relatively short and satisfies the required on / off characteristics of the engine power, but there is no lubricating oil isolated by the partition wall 58b. Since it operates in a dry environment space, it is possible to prevent the occurrence of a situation in which the expected performance is impaired due to slippage due to the lubricating oil.
[0034]
The second transfer shaft 66 is provided with a gear shaft 67 having a gear formed on the outer periphery thereof so as to be rotatable and axially movable, and a claw portion 67 a is provided at an end of the gear shaft 67. Yes. An engagement piece 66a is fixed to the second transfer shaft 66 so as to face the claw portion 67a, and the claw portion 67a meshes with the engagement piece 66a at the time of normal advance shown by a solid line in FIG. The shaft 67 rotates with the second transfer shaft 66.
The second transfer shaft 66 is provided with a reverse gear 68 between the gear shaft 67 and the low speed gear 65b, and the reverse gear 68 is rotatable on the second transfer shaft 66 via a bearing. . As shown in detail in FIG. 9, the reverse gear 68 is always connected to the gear portion 51b of the first transfer shaft via a reverse idler gear 68a rotatably supported by a case cover 60 via a bearing. When the first transfer shaft 51 rotates, it rotates in the opposite direction to the high speed gear 65a and the low speed gear 65b.
[0035]
The gear shaft 67 is formed with a circumferential groove 67c, and the shift fork 69 is engaged with the rotation of the gear shaft 67. Further, the gear shaft 67 and the reverse gear 68 have mutually opposing surfaces. Claw portions 67b and 68b are respectively provided. Further, a shift drum 70 is provided between the main case 58 and the case cover 60 so that both ends of the shift drum 70 are rotatably supported. The shift drum 70 protrudes outside the case via a lever (not shown). It is connected to the select lever 8 on the driver side.
[0036]
Therefore, when the driver operates the select lever 8 to the reverse position, the shift drum 70 is rotated, the gear shaft 67 is moved to the reverse gear 68 side by the shift fork 69, and the claw portions 67b and 68b are engaged with each other. The engagement between the portion 67a and the engagement piece 66a is released, and the gear shaft 67 can be rotated in the opposite direction to the second transfer shaft 66 by the reverse gear 68. That is, the simple and compact reverse mechanism that uses the gear shaft 67 for both forward and reverse movements cuts off the rotational power in the forward direction from the second transfer shaft 66, and the reverse direction from the reverse gear 68. The gear shaft 67 can be rotated by the rotational power to.
[0037]
As described above, the gear shaft 67 is rotated forward by any one of the forward gears 65a and 65b selected by the centrifugal transmission clutch 64, and is rotated backward by the reverse gear 68 by the driver's select lever operation. 67, the ring gear 45a of the differential mechanism 45 is always meshed.
The differential mechanism 45 rotatably supports a case 45b to which a ring gear 45a is attached and fixed by a bearing 45c between a main case 58 and a case cover 60, and a pair of umbrella-shaped pinions 45d and a pair of pins 45d in the case 45b. The umbrella-shaped side gear 45e meshes with each other and is rotatably provided. A pair of output shafts 45f attached to the side gear 45e are connected to the left and right drive shafts 80, respectively. Therefore, rotation of the gear shaft 67 transmitted through the ring gear 45a in the forward or backward direction causes the case 45b to rotate, thereby causing both side gears 45e to rotate differentially via the pinion 45d, and to the drive shaft 80. The connected left and right rear wheels 2 are driven.
[0038]
Here, as described above, in the power unit 40, the crankshaft 49 of the engine, the first transfer shaft 51, the second transfer shaft 66, and the output shaft 45f of the differential mechanism are arranged in parallel to each other. The transmission belt 53 of the transmission and the transfer shafts 51 and 66 of the mechanical transmission form a substantially U-shaped arrangement, and the engine 41 is arranged substantially flush with the differential mechanism 45 arranged substantially in the middle of the left and right rear wheels 2. This is the structure.
Therefore, since the engine 41 and the differential mechanism 45, both of which are relatively heavy, are arranged side by side on the substantially center line of the swing frame 10, the swing balance of the swing frame 10 is good.
[0039]
The case cover 60 is provided with an oil pump 71 for pumping the lubricating oil to the bearing portion of the mechanical automatic transmission 44 and the centrifugal gear clutch 64 that is oil-lubricated. The oil pump 71 is connected to the second transfer. It is connected to the shaft 66 and driven.
As shown in FIG. 10, the power unit 40 on the swing frame 10 has a differential mechanism 45 disposed at a position lower than the mechanical automatic transmission 44, and the wet environment in the case together with the mechanical automatic transmission 44 and the differential mechanism 45. The oil level H of the lubricating oil accommodated in the space is in a state where the lower part of the ring gear 45a is immersed.
[0040]
Accordingly, the oil is supplied to the gears of the differential mechanism 45 and the mechanical automatic transmission 44 by the springing up by the ring gear 45a, and the oil pump 71 pumps up the lubricating oil from the bottom of the wet environment space, and the case cover 60 The bearings of the mechanical automatic transmission 44 and the centrifugal transmission clutch 64 are lubricated through the oil passage 60c formed in the first passage, the oil passage 51f formed in the first transfer shaft, the oil passage 66b formed in the second transfer shaft, and the like. Supplying oil.
The driven pulley 52 and the centrifugal start clutch 57 serving as a dry environment are disposed at a position higher than the mechanical automatic transmission 44 with respect to the oil level H. Therefore, the wet environment combined with the shielding by the partition wall portion 58b. Intrusion of lubricating oil from the space to the dry environment space is reliably prevented.
[0041]
Note that, at the upper part of the power unit 40, the joint portion of the main case 58 and the cover case 60 on the substantially vertical surface is formed with a plurality of recesses 72a and 72b, respectively, so that the main case 58 and the cover case 60 are joined. As a result, a plurality of cavities are formed by the recesses 72a and 72b. Further, since the edges of the recesses 72a and 72b are alternately cut out, the plurality of vacant spaces are communicated with each other by a zigzag path 72c. Further, the lowermost portion of the multi-stage cavities communicates with a wet environment space in which the mechanical automatic transmission 44 and the differential mechanism 45 are accommodated by a through hole 72d, and the uppermost portion of the multi-stage cavities is externally formed by a through hole 72e. Communicating with
That is, by such a structure, an oil breather passage having a labyrinth structure is formed in the upper portion of the power unit 40, and the oil component is separated from the oil mist gas generated in the wet environment space by the oil breather passage, thereby making the wet environment space. The remaining clean gas is released to the outside.
[0042]
According to the power transmission device for a small vehicle having the above-described configuration, when the engine 41 is started and the idling operation state is established, the centrifugal start clutch 57 is disconnected and the engine power is not transmitted to the drive wheels 2.
When the engine speed increases, the centrifugal start clutch 57 is engaged, and the engine power transmitted to the belt 53 via the belt 53 is decelerated by the low speed gear 65b and transmitted to the differential mechanism 45, whereby the rear wheel 2 is Driven and rotated.
[0043]
Then, when the engine speed further increases and the rotation speed of the first transfer shaft 51 increases, the centrifugal transmission clutch 64 is engaged, and the engine power is transmitted to the differential mechanism 45 by the high speed gear 65a and the rear wheel 2 However, a shift shock caused by the reduction gear gap between the low speed gear 65 b and the high speed gear 65 a is absorbed by the continuously variable transmission by the belt type continuously variable transmission 43.
That is, if the same rotational speed of the rear wheel 2 is maintained, the rotational speed of the first transfer shaft 51 changes due to the change of the gear, but this change is reduced by the reduction ratio between the drive pulley 50 and the driven pulley 52. This is absorbed by the stepless change of the gear to reduce the shift shock.
[0044]
【The invention's effect】
As described above, according to the present invention, the load of the belt type continuously variable transmission is reduced in combination with the mechanical automatic transmission, and the centrifugal start clutch used for the belt type continuously variable transmission is operated in a dry environment. On the other hand, since the centrifugal transmission clutch used in the mechanical automatic transmission is operated in a wet environment, a small and lightweight power transmission device that satisfies the performance required for these clutches is realized and operated easily. It is possible to realize a small vehicle with low fuel consumption and low exhaust gas.
[Brief description of the drawings]
FIG. 1 is a perspective view seen from the front side of a small vehicle according to an embodiment of the present invention.
FIG. 2 is a perspective view seen from the back side of the small vehicle according to the embodiment of the present invention.
FIG. 3 is a perspective view of a small vehicle according to an embodiment of the present invention in plan view.
FIG. 4 is a side perspective view of the small vehicle according to the embodiment of the present invention.
FIG. 5 is a plan view showing a swing frame structure of a small vehicle according to an embodiment of the present invention.
FIG. 6 is a side view showing a swing frame structure of a small vehicle according to an embodiment of the present invention.
FIG. 7 is a side view showing a mount portion of a power unit of a small vehicle according to an embodiment of the present invention.
FIG. 8 is a cross-sectional plan view of a power unit of a small vehicle according to an embodiment of the present invention.
FIG. 9 is a plan view showing a part of a power unit of a small vehicle according to an embodiment of the present invention in different cross sections.
FIG. 10 is a partial cross-sectional side view of a power unit of a small vehicle according to an embodiment of the present invention.
[Explanation of symbols]
2: rear wheel (drive wheel), 10: swing frame,
40: Power unit, 41: Engine,
42: Belt type continuously variable transmission, 44: Mechanical two-speed automatic transmission,
45: Differential mechanism, 51: First transfer shaft,
57: Centrifugal start clutch, 58b: Bulkhead part,
64: Centrifugal transmission clutch, 65a: High speed gear,
65b: low-speed gear, 66: second transfer shaft,

Claims (2)

The engine and mechanical automatic transmission are connected via a belt-type continuously variable transmission,
The belt type continuously variable transmission is provided with a centrifugal start clutch that connects and transmits engine power when the rotational speed increases.
The mechanical automatic transmission is provided with a centrifugal shift clutch that switches the gear for connecting and transmitting power when the rotational speed increases, from the low speed gear to the high speed gear,
The belt type continuously variable transmission is housed in a case in a dry environment and the centrifugal start clutch is operated in the dry environment, while the mechanical automatic transmission is housed in the case together with lubricating oil and the centrifugal transmission clutch is placed in an oil lubricated environment. Make it work
Power transmission of a small vehicle characterized in that the centrifugal start clutch and the centrifugal shift clutch are arranged coaxially and the high-speed drive gear and the low-speed drive gear of the mechanical automatic transmission are arranged adjacent to each other. apparatus. The power transmission device for a small vehicle according to claim 1,
The high-speed gear that meshes with the high-speed drive gear and the low-speed gear that meshes with the low-speed drive gear are arranged coaxially, and a one-way clutch that allows only overtaking rotation of the low-speed gear by the high-speed gear is interposed between the high-speed gear and the low-speed gear. power transmission system for a small vehicle, characterized in that instrumentation was.

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