JPH0745905B2 - Belt ratio controller for continuously variable transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt ratio control device for a continuously variable transmission, and in particular, controls a belt ratio by switching between open loop control and closed loop control depending on a vehicle operating condition. The present invention relates to a belt ratio control device for a continuously variable transmission.

[Prior Art] In a vehicle, a transmission is interposed between an internal combustion engine and driving wheels. This transmission system changes the driving force of the drive wheels and the traveling speed in accordance with the traveling condition of the vehicle that changes in a wide range, and makes the internal combustion engine fully exhibit its performance. The transmission is formed between both pulley part pieces of a pulley having a fixed pulley part piece fixed to the rotary shaft and a movable pulley part piece mounted on the rotary shaft so as to be able to come into contact with and separate from the fixed pulley part piece. There is a continuously variable transmission that changes the gear ratio (belt ratio) by increasing or decreasing the radius of rotation of a belt wound around a pulley by increasing or decreasing the width of a groove to transmit power. Examples of this continuously variable transmission include, for example, JP-A-57-186656, JP-A-59-43249, JP-A-59-77159, and JP-A-59-77159.
No. 61-233256, respectively.

[Problems to be Solved by the Invention] By the way, in a conventional belt ratio control device for a continuously variable transmission, the ratio is changed to a full low ratio by the characteristics of the ratio solenoid duty and the primary pressure of the continuously variable transmission.
In order to achieve F / L, the duty is set lower than the ratio solenoid null duty value NNOMR.

At this time, when the ratio is set to full low F / L in the normal start mode, the ratio solenoid is driven with a duty of 0% to perform open loop control RDIMOD.

When the clutch slip CLUSLP becomes smaller than the clutch slip trigger value CSTR, the drive mode is entered.The gear change control in this drive mode is a closed loop control RNEMOD that feedback-controls the engine speed NE, Is controlled by an intermediate duty centered on the ratio solenoid null duty value NNOMR.

Therefore, as shown in FIG. 4, when the normal start mode is changed to the drive mode, the ratio solenoid is driven with a duty of 0% in the normal start mode, so that oil is not supplied to the primary sheave and the normal start is started. Simultaneously with the transition from the mode to the drive mode, the shift control changes from open loop control to closed loop control, and the duty also changes from 0% to an intermediate duty.

Also, the ratio is controlled to change to the overdrive O / D direction by changing the shift control state to closed loop control.

However, due to the large volume of the primary sheave,
A large oil flow rate is required during the shift control, and it takes a relatively long time from the change of the drive duty of the ratio solenoid to the actual change of the ratio.

Therefore, the engine speed NE is the target engine speed NESP.
It becomes difficult to converge to R, the integrated value is accumulated, and as shown in FIG. 6, the oil is rapidly supplied to the primary sheave at the A portion, the line pressure fluctuates, and the clutch that divides the line pressure is divided. The pressure also fluctuates, which causes various problems in clutch control.

Further, since the difference between the target engine speed NESPR and the engine speed NE becomes large, the engine speed NE causes hunting, which may cause a variation in the vehicle speed NCO.

Therefore, in order to eliminate the above-mentioned inconvenience, an object of the present invention is to reduce the vehicle speed in a normal start mode which is a control mode before complete clutch engagement in start control of a belt ratio control device of a continuously variable transmission. When it exceeds a predetermined value, the open-loop control that directly outputs the shift control amount that realizes the maximum gear ratio is switched to the closed-loop control that performs feedback control so that the gear ratio matches the target near the maximum gear ratio. By providing a control unit that controls the belt ratio in preparation for gear shifting in the clutch direct-coupling control mode after the start control, the control unit supplies oil to the primary sheave to shift from the normal start mode to the drive mode. Prevents a sudden increase in pressure and prevents the line pressure and clutch pressure from being affected. It is possible to reduce the occurrence of hunting in the drive mode by stopping the engine and to make the engine speed quickly converge to the target engine speed, and it is possible to deal with only a part of the program of the control section to improve the continuously variable transmission. It is to realize the belt ratio control device of the machine.

[Means for Solving the Problems] In order to achieve this object, the present invention is directed to a space between both pulley part pieces of a fixed pulley part piece and a movable pulley part piece that is attached to and detachable from the fixed pulley part piece. In the belt ratio control device of the continuously variable transmission for controlling the shift to change the gear ratio by increasing or decreasing the groove width of the belt and increasing or decreasing the radius of gyration of the belt wound around the pulleys, the control before the complete clutch engagement in the start control When the vehicle speed exceeds a predetermined value in the normal start mode, which is the mode, open-loop control that directly outputs the shift control amount that realizes the maximum gear ratio is used, and the gear ratio matches the target near the maximum gear ratio. The belt ratio is controlled to prepare for the gear shift in the clutch direct-coupling control mode after the start control by performing the switching operation to the closed loop control in which the feedback control is performed. It is characterized in that a control unit for controlling is provided.

[Operation] According to the invention described above, when the vehicle speed becomes equal to or higher than the predetermined value in the normal start mode, the control unit switches the operation from the open loop control to the closed loop control to control the belt ratio to the primary sheave. Oil is supplied to prevent a sudden increase in the primary pressure when shifting from the normal start mode to the drive mode, to prevent the line pressure and the clutch pressure from being affected, and to reduce the occurrence of hunting in the drive mode. Is quickly converged to the target engine speed, and only a part of the program in the control section is improved.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 5 show an embodiment of the present invention. Fourth
In the figure, 2 is a belt drive type continuously variable transmission, 2A is a belt, 4 is a drive side pulley, 6 is a drive side fixed pulley part,
Reference numeral 8 is a drive side movable pulley section piece, 10 is a driven side pulley section, 12 is a driven side fixed pulley section piece, and 14 is a driven side movable pulley section piece. As shown in FIG. 4, the drive side pulley 4 includes a drive side fixed pulley portion 6 fixed to a rotary shaft 16 and a rotary shaft 16.
And a drive side movable pulley portion 8 mounted on the rotary shaft 16 so as to be movable in the axial direction and not rotatable. Also,
Like the drive pulley 4, the driven pulley 10 also has a driven fixed pulley portion 12 and a driven movable pulley portion 14.

The drive side movable pulley part 8 and the driven side movable pulley part
First and second housings 18 and 20 are attached to 14 respectively, and first and second hydraulic chambers 22 and 24 are formed respectively. At this time, in the second hydraulic chamber 24 on the driven side, the second hydraulic chamber 24
An urging means 26 including a spring or the like for urging the second housing 20 in the expanding direction is provided.

An oil pump 28 is provided on the rotary shaft 16, and the oil pump 28 is connected to the first and second hydraulic chambers 22 and 24 by the first and second oil passages 30 and 32, respectively, and at the middle of the first oil passage 30. A primary pressure control valve 34, which is a shift control valve that controls the primary pressure, which is the sheave pressure of the input shaft, is interposed in this.
The control in the line pressure by the third oil passage 36 to the first oil passage 30 of the oil pump 28 side of the primary pressure control valve 34 (typically 5~25kg / cm ²⁾ to a constant pressure (3-4 kg / cm ²⁾ The primary pressure control valve 34 is communicated with the primary pressure control valve 34 by the fourth oil passage 40.

Further, a line pressure control valve 44 having a relief valve function for controlling the line pressure that is a pump pressure is connected in the middle of the second oil passage 32 by a fifth oil passage 46, and the line pressure control valve 44
The sixth oil passage 48 connects the second three-way solenoid valve 50 for controlling the line pressure.

Further, the line pressure control valve 44 has a second position
A clutch pressure control valve 52 for controlling the clutch pressure is connected in the middle of the second oil passage 32 on the hydraulic chamber 24 side by a seventh oil passage 54, and the clutch pressure control valve 52 is controlled by an eighth oil passage 56 for clutch pressure control. The third direction solenoid valve 58 is communicated.

Further, the primary pressure control valve 34, the first solenoid valve 42 for primary pressure control, the constant pressure control valve 38, the sixth oil passage 48,
The second solenoid valve 50 for line pressure control and the clutch pressure control valve 52 are connected by the ninth oil passage 60, respectively.

The clutch pressure control valve 52 is connected to the hydraulic starting clutch 62 by a tenth oil passage 64, and a pressure sensor 68 is connected in the middle of the tenth oil passage 64 by a first oil passage 66. The pressure sensor 68 can directly detect the hydraulic pressure when controlling the clutch pressure in the hold and start modes, and contributes to commanding the detected hydraulic pressure to be the target clutch pressure. Further, since the clutch pressure becomes equal to the line pressure in the drive mode, it also contributes to the line pressure control.

An input shaft rotation detection gear 70 is provided outside the first housing 18, and a first rotation detector 72 on the input shaft side is provided near the outer peripheral portion of the input shaft rotation detection gear 70. An output shaft rotation detection gear 74 is provided outside the second housing 20, and a second rotation detector 76 on the output shaft side is provided near the outer peripheral portion of the output shaft rotation detection gear 74. Then, the first rotation detector 72 and the second rotation detector
The detection signal from the rotation detector 76 is output to the control unit 82, which will be described later, to grasp the engine speed and the belt ratio.

The hydraulic starting clutch 62 is provided with an output transmission gear 78,
A third rotation detector 80 for detecting the rotation of the final output shaft is provided near the outer peripheral portion of the gear 78. That is, the third rotation detector 80 detects the rotation of the reduction gear, the differential gear, the drive shaft, and the final output shaft directly connected to the tire, and can detect the vehicle speed. The second rotation detector 76 and the third rotation detector 80 can also detect the rotation around the hydraulic starting clutch 62, which contributes to the detection of the clutch slip amount.

Further, a throttle opening of a carburetor (not shown) of the vehicle, engine rotation from the first to third rotation detectors 72, 76, 80,
A control unit 82 for inputting various conditions such as vehicle speed and changing the duty ratio to perform shift control is provided. The control unit 82 controls the first three-way solenoid valve 42 for primary pressure control, the constant pressure control valve 38, and the line pressure control first. The two-way three-way solenoid valve 50 and the third three-way solenoid valve 58 for clutch pressure control are controlled to open and close, and the pressure sensor 68 is also controlled. Further, the various signals input to the control unit 82 and the functions of the input signals will be described in detail. The detection signals of the shift lever position ... P, R, N, D, L, etc. Required line pressure, ratio, clutch control, carburetor throttle opening detection signal ... Engine torque is detected from the memory input in the program in advance, target ratio or target engine speed is determined, carburetor idle position detection signal …… Compensation of the carburetor throttle position sensor and improvement of control accuracy, accelerator pedal signal …… Detects the driver's intention based on the accelerator pedal depression state, determines the control direction during running or starting, and brake signal …… Detects whether the brake pedal is depressed or not, determines the control direction such as clutch disengagement, and Mode option signal …… The performance of the vehicle is sports (or economy)
Use as an option for

The control unit 82 controls the vehicle speed in the normal start mode, which is a control mode before complete clutch engagement in start control.
When the NCO exceeds a predetermined value, open loop control that directly outputs the shift control amount that realizes the maximum gear ratio, and closed loop control that performs feedback control so that the gear ratio matches the target with a target near the maximum gear ratio It is configured to control the belt ratio so as to prepare for a gear shift in the clutch direct-coupling control mode after the start control.

More specifically, the control unit 82 inputs the detection signal of the vehicle speed NCO, and when the vehicle speed NCO becomes equal to or higher than a vehicle speed trigger value NCOTR which is a predetermined value, a shift that realizes the maximum gear ratio even in the normal start mode. The shift control method is changed from open loop control that directly outputs the control amount to closed loop control that performs feedback control so that the gear ratio matches the target near the maximum gear ratio.

Also, in the normal start mode, which is the control mode before complete clutch engagement in start control, the vehicle speed NCO switches from open loop control to closed loop control with the ratio target, and drive mode is the clutch direct connection control mode after start control. In this case, the engine speed target and the ratio target are closed-loop controlled.

Reference numeral 84 is a piston of the hydraulic starting clutch 62, 86 is an annular spring, 88 is a first pressure plate, 90 is a friction plate, 92 is a second pressure plate, 94 is an oil pan,
96 is an oil filter.

Next, the operation will be described.

In the belt drive type continuously variable transmission 2, as shown in FIG. 4, the oil pump 28 located on the rotary shaft 16 operates in response to the drive of the rotary shaft 16, and the oil is oil pan 94 at the bottom of the transmission. Is absorbed through the oil filter 96. The line pressure, which is the pump pressure, is controlled by the line pressure control valve 44, and if the leakage amount from the line pressure control valve 44, that is, the escape amount of the line pressure control valve 44 is large, the line pressure becomes low,
On the contrary, if it is small, the line pressure will be high.

Further, the line pressure control valve 44 has a shift control characteristic that changes the line pressure in the full low state, the full over top state, and the fixed ratio state to perform three-stage control.

The operation of the line pressure control valve 44 is performed by a dedicated second three-way solenoid valve 50.
The line pressure control valve 44 operates following the operation of the second three-way solenoid valve 50. The second three-way solenoid valve 50 is controlled at a duty ratio of a constant frequency. . That is, when the duty ratio is 0%, the second three-way solenoid valve 50 does not operate at all, the output side is connected to the atmosphere side, and the output hydraulic pressure becomes zero. Also, the duty ratio is 100%
The second three-way solenoid valve 50 operates so that the output side is connected to the control hydraulic pressure side, the maximum output hydraulic pressure is the same as the control pressure, and the output hydraulic pressure is varied according to the duty ratio.
Therefore, the characteristic of the second three-way solenoid valve 50 is substantially linear, the line pressure control valve 44 can be operated in an analog manner, and the duty ratio of the second three-way solenoid valve 55 can be arbitrarily changed. Line pressure can be controlled. The operation of the second three-way solenoid valve 50 is controlled by the controller 82.

The primary pressure for shift control is the primary pressure control valve 34
Similarly to the line pressure control valve 44, the operation of the primary pressure control valve 34 is controlled by the dedicated first three-way solenoid valve 42. This first three-way solenoid valve 42
Used to connect the primary pressure to the line pressure or the primary pressure to the atmosphere side. Conduct the line pressure to shift the belt ratio to the full overdrive side, or to the atmosphere side to shift to the full low side. It is what makes me.

The clutch pressure control valve 52 that controls the clutch pressure is connected to the line pressure side when the maximum clutch pressure is required, and is connected to the atmosphere side when the minimum clutch pressure is set. Like the line pressure control valve 44 and the primary pressure control valve 34, the clutch pressure control valve 52 is also a dedicated third three-way solenoid valve.
The operation is controlled by 58, and the explanation is deleted. The clutch pressure varies within the range from the minimum atmospheric pressure (zero) to the maximum line pressure.

There are four basic patterns for clutch pressure control which will be described later. These basic patterns are (1), Neutral mode ...... When the shift position is N or P and the clutch is completely disengaged, the clutch pressure is the minimum pressure (zero). (2) Hold mode: If the shift position is D or R and the throttle is released and there is no intention to run, or if you want to decelerate and cut the engine torque while running, the clutch pressure is low enough to contact the clutch ( 3), Start mode: When trying to connect the clutch again at the time of starting or after the clutch is disengaged, the clutch pressure depends on the engine generated torque (clutch input torque) that prevents the engine from rising and can operate the vehicle smoothly. Appropriate level (4), drive mode ..... If the fully coupled, There are four high-level clutch pressure having a margin to withstand sufficiently the engine torque. The basic pattern (1) is performed by a dedicated switching valve (not shown) that is interlocked with the shift operation, and the other (2), (3), and (4) are performed by the control unit 82 by the first to third solenoid valves 42. , 50, 58 duty ratio control. Particularly, in the state (4), the clutch pressure control valve 52 connects the seventh oil passage 54 and the tenth oil passage 64 so that the maximum pressure is generated, and the clutch pressure becomes the same as the line pressure.

Further, the primary pressure control valve 34 and the line pressure control valve 44,
The clutch pressure control valve 52 is the first to third three-way solenoid valve 4
Although controlled by the output hydraulic pressures from 2, 50, 58, respectively, the control hydraulic pressure for controlling these first to third three-way solenoid valves 42, 50, 58 is a constant hydraulic pressure produced by the constant pressure control valve 38. This control oil pressure is always higher than the line pressure, but is a stable and constant pressure. Further, the control oil pressure is also introduced into the respective control valves 34, 44, 52 to stabilize these control valves 34, 44, 52.

Next, electronic control of the belt drive type continuously variable transmission 2 will be described.

The continuously variable transmission 2 is hydraulically controlled, and in response to a command from the control unit 82, an appropriate line pressure for belt holding and torque transmission, a primary pressure for changing a gear ratio, and a clutch are reliably connected. The respective clutch pressures are set to be applied.

The belt ratio control of the belt drive type continuously variable transmission 2 will be described with reference to FIG.

First, the target ratio value RATSP and the target engine speed NESPR are calculated by a measure (not shown), and these target ratio value RAT
Find the difference between the actual value of SP and the target engine speed NESPR.

In other words, the target ratio value RATSP is calculated by calculating the error between the target ratio value RATSP and the belt ratio RATC (100), multiplying this error by a proportional gain (102), and comparing the target ratio value RATSP determined by the throttle opening and the vehicle speed with the belt ratio. The control mode RATMOD for feedback control of the ratio RATC is calculated (104).

Further, as the target engine speed NESPR, an error between the target engine speed NESPR and the actual engine speed NE is calculated (106). At this time, when the error becomes large, the duty ratio becomes large as a result, the opening of the primary pressure control valve 34 becomes large, and the shift speed becomes high. Control mode RNEMOD that multiplies the error by proportional gain (108) and feedback-controls the engine speed to the target engine speed NESPR determined by the throttle opening and vehicle speed
(110).

Then, set the target ratio value in the ratio control mode.
Control mode RATMOD for feedback control of belt ratio RATC to RATSP and target engine speed NESP
The control mode RNEMOD for feedback control of the engine speed to R is switched (112).

Furthermore, the error of either one of the two control modes RATMOD or RNEMOD is multiplied by a proportional gain (114), and this value is multiplied by the integral gain (116) and the value obtained by performing the integration processing (118) is compared. After that, NNOMR (ratio solenoid null duty value) is added to obtain the error (120).

Then, the error and the duty value are selected depending on whether or not the control mode RDIMOD state in which the ratio solenoid is driven with a constant duty value is selected (122), and the output duty OPWRAT is set, and each solenoid valve is excited by this output duty OPWRAT. It is what makes me.

A belt ratio control flowchart of the belt drive type continuously variable transmission 2 will be described with reference to FIG.

First, a belt ratio control program is started (200) by driving the belt drive type continuously variable transmission 2.

Next, it is judged whether the driving condition of the vehicle is the normal start mode (202). If YES, the clutch slips.
Compare CLUSLP with clutch slip trigger value CSTR (20
4) If NO, determine whether it is in drive mode (20
6) Do.

Then, in the comparison between the clutch slip CLUSLP and the clutch slip trigger value CSTR (204), if CLUSLP> CSTR, the vehicle speed NCO is compared with the vehicle speed trigger value NCOTR (208).
If CLUSLP ≤ CSTR, it is determined that the clutch is engaged, the normal start mode is set to the drive mode (210), and the shift control method is fed back the engine speed NE to the target engine speed NESPR. The control mode RNEMOD is controlled, and the engine speed NE is closed-loop controlled to the target engine speed NESPR determined based on the driving schedule.

In addition, when the vehicle speed NCO and the vehicle speed trigger value NCOTR are compared (208), and if NCO <NCOTR, the duty is set to 0% (212) and the return is made as open loop control (21
Move to 8).

Then, in the case of NCO ≧ NCOTR in the comparison (208),
Set the control mode RATMOD to feedback control the belt ratio to the target ratio rotation speed determined by the throttle opening and vehicle speed (214), perform the closed loop control targeting the ratio full low F / L, and then return (218). Move. By this closed loop control, oil is supplied to the primary sheave, and the primary pressure slightly increases as shown by the one-dot chain line in FIG.

Furthermore, in the judgment (206) as to whether or not the drive mode is set, in the case of NO, the process shifts to the return (218), and in the case of YES, the engine speed is changed with respect to the target engine speed determined by the throttle opening and the vehicle speed. Is set to the control mode RNEMOD for feedback control of (216), and then the process is returned to (218).

Furthermore, after the drive mode is set (210), the control mode RNEMOD that feedback-controls the engine speed with respect to the target engine speed determined by the throttle opening and the vehicle speed is set (216),
After that, it shifts to the return (218).

Further, referring to FIG. 3, the relationship between the duty ratio of each control valve and the pressure is shown, and the ratio shift point NNOM
At a duty value exceeding R (ratio solenoidal duty value), the internal pressure of the sheave of the input shaft becomes larger than the internal pressure of the output shaft, and the gear shift upshifts from full low to full overdrive. At a duty value equal to or less than the shift point NNOMR (ratio solenoidal duty value) of the ratio, a downshift occurs in the opposite direction, and when the ratio is in the full low state, the full low is fixed.

As a result, when the vehicle speed NCO becomes equal to or higher than the vehicle speed trigger value NCOTR when the vehicle operating state is the normal start mode,
By switching from open loop control to closed loop control and supplying oil to the primary sheave, it is possible to prevent a sudden increase in primary pressure during the transition from normal start mode to drive mode, which affects line pressure and clutch pressure. It is possible to reduce the occurrence of hunting in the drive mode, which is practically advantageous.

In addition, by preventing a sudden increase in the primary pressure when the vehicle operating state shifts from the normal start mode to the drive mode, the engine speed can quickly converge to the target engine speed, improving vehicle stability. Can be made.

Further, since it can be dealt with only by improving a part of the program in the control unit 82, the configuration is not complicated, the size is not increased, the manufacturing is easy, the cost can be kept low, and it is economically advantageous. Is.

[Effects of the Invention] As described in detail above, according to the present invention, the vehicle speed is equal to or higher than a predetermined value in the normal start mode which is the control mode before complete clutch engagement in the start control of the belt ratio control device of the continuously variable transmission. If it becomes, the open-loop control that directly outputs the shift control amount that realizes the maximum gear ratio is switched to the closed-loop control that performs feedback control so that the gear ratio matches the target near the maximum gear ratio, and then starts. In order to prepare for gear shifting in the clutch direct connection control mode after control, a control unit that controls the belt ratio is provided, so when the vehicle speed exceeds a predetermined value, switching from open loop control to closed loop control is performed, and oil is added to the primary sheave. In the clutch direct connection control mode after starting control from the normal start mode. It is possible to prevent a sudden increase in the primary pressure at the time of shifting to the drive mode, which does not affect the line pressure and the clutch pressure, and to reduce the occurrence of hunting in the drive mode. In addition, by preventing a sudden increase in the primary pressure when the vehicle operating state shifts from the normal start mode to the drive mode, the engine speed can quickly converge to the target engine speed, improving vehicle stability. Can be done. Further, since it can be dealt with only by improving a part of the program in the control unit, the structure is not complicated and the cost can be kept low, which is economically advantageous.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention, and FIG. 1 is an explanatory view for calculating a target engine speed and a target ratio value.
FIG. 4 is a flow chart for ratio control of a belt drive type continuously variable transmission, FIG. 3 is a diagram showing a relationship between pressure and duty ratio in each control valve, and FIG. 4 is a block diagram of the belt drive type continuously variable transmission. FIG. 5 is a time chart when shifting from the normal start mode to the drive mode. FIG. 6 is a time chart when shifting from the normal start mode to the drive mode, which shows the prior art of the present invention. In the figure, 2 is a belt drive type continuously variable transmission, 2A is a belt, 4 is a drive side pulley, 10 is a driven side pulley, 30 is a first oil passage, 32 is a second oil passage, and 34 is a primary pressure control valve. , 36 is a third oil passage, 38 is a constant pressure control valve, 40 is a fourth oil passage, 42 is a first three-way solenoid valve, 44 is a line pressure control valve, 46 is a fifth oil passage, 48 is a sixth oil passage, 50 is a second three-way solenoid valve, 52 is a clutch pressure control valve, 54 is a seventh oil passage, 56 is an eighth oil passage, 58 is a third three-way solenoid valve, 60 is a ninth oil passage, 62 is a hydraulic starting clutch, 64 is a 10th oil passage, 66 is an 11th oil passage, 68 is a pressure sensor, 72 is a first rotation detector, 76 is a second rotation detector, 80 is a third rotation detector, 82 is a control unit, and 94 is The oil pan and 96 are oil filters.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsumi Takumi 840 Chiyoda-cho, Himeji City, Hyogo Prefecture Mitsubishi Electric Co., Ltd. Himeji Manufacturing Co., Ltd. (72) Inventor Hiroaki Yamamoto 1 at 13 Sadamoto-cho, Himeji City, Hyogo Prefecture Mitsubishi Electric Control Software Himeji Business Co., Ltd. (56) Reference JP-A-62-191239 (JP, A)

Claims (1)

[Claims] Claim: What is claimed is: 1. A fixed pulley portion and a movable pulley portion mounted on the fixed pulley portion so as to be able to come into contact with and separate from each other, so that the groove width between the pulley portions is increased to increase the width of the belt wound around the pulleys. In a belt ratio control device for a continuously variable transmission that performs gear shift control to increase or decrease the radius of gyration to change the gear ratio, the vehicle speed exceeds a predetermined value in the normal start mode, which is the control mode before complete clutch engagement in start control. In the case of the maximum gear ratio, the open loop control that directly outputs the gear change control amount is switched to the closed loop control that performs feedback control so that the gear ratio is close to the target near the maximum gear ratio. Of a continuously variable transmission characterized in that a control unit for controlling a belt ratio is provided to prepare for a shift in the clutch direct connection control mode. Ratio control apparatus.