JPH10141458A - Continuously variable transmission controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuously variable transmission controller which ensures the minimum running function by a simple and low-cost configuration. SOLUTION: An oil passage 56 branched from a control output port oil passage 53 of a solenoid valve 12 is led to a fail-safe valve 13 to control pressure in an oil passage 69 in accordance with pressure of an oil passage 58 branched from an oil passage 57. Moreover, pressure of the oil passage 57 is introduced into a primary pressure control valve 19 to control pressure of an oil passage 68 by pressure of an oil passage 80 and the oil passage 57. When output pressure of the solenoid valve 12 drops below a specified value and a failure occurs, the fail-safe valve 13 is changed over to the right position so that pressure of an oil passage 55 and an oil passage 51 which detour the solenoid valves 12 and 11 is communicated with the oil passage 57 and the oil passage 80. As a result, it is possible to transmit large torque because primary pressure and secondary pressure are controlled in such a manner that they become the maximum values. Consequently, it is possible to ensure tensile force of a belt which hardly obstructs actual running at the time of fail and ensure the minimum running function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling a speed change of a belt-type continuously variable transmission.

[0002]

2. Description of the Related Art Hitherto, as a hydraulic control circuit of a continuously variable transmission, a configuration in which a solenoid valve generates a primary pressure and a secondary pressure has been known. In such a hydraulic control circuit of a continuously variable transmission, effects such as improvement of fuel consumption, improvement of shift feeling, improvement of acceleration performance, and the like can be obtained by electronically controlling the gear ratio and belt tension of the continuously variable transmission. .
However, the gear ratio and the belt tension cannot be controlled due to the malfunction of the electronic control, and there is a possibility that the running function is lost.

Therefore, in the continuously variable transmission control device disclosed in Japanese Patent Application Laid-Open No. 7-4485, a solenoid valve is newly added, and the shift valve is operated by operating the solenoid valve to thereby change the primary pressure and the secondary pressure. The pressure is set to the same pressure so that a minimum running function is ensured during a failure.

[0004]

However, such a conventional continuously variable transmission control device has a problem in that the cost is increased because an expensive solenoid valve and a drive circuit are required. In addition, the solenoid valve has a problem that it is liable to be broken down as compared with the mechanical valve, and thus lacks reliability. The present invention has been made to solve such a problem,
It is an object of the present invention to provide a continuously variable transmission control device that secures a minimum traveling function with a simple and low-cost configuration.

[0005]

According to the continuously variable transmission control device of the present invention, the first pressure generating means for generating the first pressure adjusted according to the torque input from the drive shaft. And a bypass valve that supplies pressure to the first and second pistons, bypassing a second pressure generating means that generates a second pressure that is adjusted in accordance with the target value of the gear ratio, so that the second pressure is reduced to a predetermined value. Since the pressure is supplied to the first and second pistons when it becomes lower, a minimum traveling function can be ensured by the bypass valve when the electronic control fails. Further, a simple and low-cost configuration can be realized by the mechanical bypass valve.

According to the continuously variable transmission control device of the second aspect of the present invention, the bypass valve is set so that the transmission belt clamping force of the first pulley and the transmission belt clamping force of the second pulley are equal. Therefore, when the electronic control fails, the gear ratio between the drive shaft and the driven shaft becomes 1. Therefore, at the time of a failure, a minimum traveling function can be ensured.

According to the continuously variable transmission control device of the third aspect of the present invention, the bypass valve bypasses the pilot valves of the first and second pressure generating means, and bypasses the main valves of the first and second pressure generating means. , The first and second pressure generating means can be small and lightweight solenoid valves. Therefore, the size and weight of the control device can be reduced.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 shows a power transmission mechanism in which the continuously variable transmission control device according to one embodiment of the present invention is applied to a belt-type continuously variable transmission (hereinafter, “belt-type continuously variable transmission” is referred to as CVT).
Shown in The torque converter 40 is connected to the output shaft 81 of the motor 3.
Are connected. The torque converter 40 includes a lock-up clutch 41 and the torque converter 4
The output side of 0 is connected to the rotating shaft 82. Rotating shaft 82
Is connected to the forward / reverse switching mechanism 4. The forward / reverse switching mechanism 4 has a front clutch 6 and a rear clutch 7. The forward / reverse switching mechanism 4 is connected to a drive shaft 83, and the drive shaft 83 has a primary pulley 3 as a first pulley.
5 are provided. The primary pulley 35 is movable in the axial direction of the drive shaft 83 by hydraulic pressure acting on a primary pulley cylinder chamber 35a as a first piston. The primary pulley 35 is communicatively connected to the secondary pulley 34 as a second pulley by the transmission belt 15. The secondary pulley 34 is movable in the axial direction of the driven shaft 84 by hydraulic pressure acting on a secondary pulley cylinder chamber 34a as a second piston.

The primary pulley 35, the transmission belt 15, and the secondary pulley 34 constitute a CVT. The CVT is used for a vehicle, and the power of the prime mover 3 is transmitted to a differential mechanism 85 via a driven shaft 84 and transmitted to left and right wheels (not shown). Next, the CVT hydraulic control device will be described. As shown in FIG. 1, the hydraulic control device includes a shift lever 1, a manual valve 2, a neutral control valve 5, a hydraulic pump 8, a pressure reducing valve 9, electromagnetic control valves 11 and 12 as first and second pressure generating means, Fail safe valve 13 as shuttle valve, shuttle valve 14, line pressure control valve 1
7. Primary pressure control valve 1 as first pressure generating means
9, secondary pressure control 28 as second pressure generating means,
Solenoid valve 32, oil cooler 33, lock-up switching valve 3
8 and the like.

The manual valve 2 is connected to the shift lever 1 via a linkage 43, and is switched by a driver's operation. Specifically, P, R, N, D, 3, 2
1 and (R), (P, N) and (D, 3, 2,...) At three positions as shown in FIG.
It is switched to 1). High pressure is output from the port oil passage 44 to the output port oil passages 45 and 46 according to the switching position. In FIG. 2, a circle indicates that high pressure is output, and a blank indicates drain pressure. Output port oil passage 45
And 46 are led to the neutral control valve 5 and to the front clutch 6 and the rear clutch 7, respectively. The opening area of the neutral control valve 5 is variably controlled by an electromagnetic valve 32 via an oil passage 47. By switching from the neutral to the D range by the variable control, the introduction of the pressure oil to the front clutch 6 is gradually performed, and the shock at the time of the range switching can be reduced. In the case of switching from the neutral to the R range, the introduction of the pressure oil to the rear clutch 7 is performed gradually, so that the shock at the time of the range switching can be reduced.

The hydraulic oil discharged from the hydraulic pump 8 passes through an oil passage 63, one of which is guided to a line pressure control valve 17 and is introduced into an oil passage 61, and the other through an oil passage 62. Is introduced to the left side of the drawing. Oil passage 61
The position of the line pressure control valve 17 is subjected to self-feedback control by balancing the force between the pressure of the line pressure control valve 17 and the pressure in the left-hand side different diameter portion of the line pressure control valve 17. Then, the pressure oil in the oil passage 63 is discharged to the drain or the lubrication passage 18, and the pressure of the oil passage 63 as the line pressure is controlled in response to the pressure of the oil passage 61.

An oil passage 64 branched from the oil passage 63 having the controlled line pressure is led to the pressure reducing valve 9. Further, an oil passage 49 branched from the downstream port oil passage 50 of the pressure reducing valve 9 is guided below the pressure reducing valve 9 in the figure, and the spring 22 and the force are balanced and controlled. Then, the pressure of the oil passage 50 is controlled to a constant value. Further, the oil passage 63 of the line pressure is connected to the oil passages 65 and 66.
The pressure is guided to the secondary pressure control valve 28 and the primary pressure control valve 19, and the pressure in the oil passages 70 and 68 is controlled in accordance with the pressure in the oil passages 58, 57 and 80, respectively. The oil passage 69 and the oil passage 68 led from the oil passage 70 are led to the secondary pressure and the primary pressure, respectively. The secondary pressure and the primary pressure determine the speed ratio of the CVT and the belt tension. The relationship between the pressure of the secondary pressure and the primary pressure and the operating state is such that when the secondary pressure is higher than the primary pressure as shown in FIG.
When the speed ratio of the CVT is higher than 1 or the belt tension is low and the speed is low, and the primary pressure is higher than the secondary pressure, the speed ratio of the CVT is lower than 1 or the belt tension is high and the speed is high. When the secondary pressure and the primary pressure have the same value, C
The speed ratio of the VT is 1.

The oil passage 50 is led to the solenoid valve 12, and the solenoid valve 1
The second control output port oil passage 53 is guided to the fail-safe valve 13. An oil passage 56 branched from the oil passage 53 is guided to the right side of the fail-safe valve 13 in the drawing. The fail-safe valve 13 is switched to the right end or the left end in the figure according to the balance between the force of the spring 25 and the oil path 56 on the left side in the figure.
If the pressure of the oil passage 53 is maintained at a predetermined value, the spring 25 is contracted by being pressed by the pressure of the oil passage 53.
Thus, the oil passage 57 and the oil passage 53 are communicated. Oilway 57
The oil passage 58 branched from the oil passage 58 is guided to the right side in the drawing of the secondary pressure control valve 28 through the throttle 30, and the pressure of the oil passage 69 as the secondary pressure is controlled according to the pressure of the oil passage 58.

The oil passage 69 communicates with the oil passage 51, and the secondary pressure is introduced into the solenoid valve 11 via the oil passage 52 branched from the oil passage 51, and the output port oil passage 54 is provided by the solenoid valve 11. Is controlled. The output port oil passage 54 is guided to the fail-safe valve 13, and when the fail-safe valve 13 is located at the position shown in FIG.
The control pressure of the solenoid valve 11 is introduced to the right side of the primary pressure control valve 19 in the drawing. In addition, the pressure of the oil passage 57, which is the control pressure of the solenoid valve 12, is also changed by the primary pressure control valve 19.
Is installed in a separate room on the right side of FIG. That is, the solenoid valve 1
Oil passages 80 and 57 which are control pressures of 1 and 12
The pressure of the oil passage 68 as the primary pressure is controlled by this pressure.

The oil passage 59 branched from the oil passage 58 and the oil passage 60 branched from the oil passage 80 are guided to the shuttle valve 14. The shuttle valve 14 selects the higher pressure of the oil passage 59 and the oil passage 60, and the selected pressure is introduced to the right side of the line pressure control valve 17 through the oil passage 61 in the drawing, and the line pressure is controlled. . Thus, by selecting the specifications of the primary pressure and secondary pressure control valves 19 and 28, a line pressure slightly higher than the primary pressure and the secondary pressure can be set as shown in FIG.

On the right side of the primary pressure control valve 19 in the figure, an oil passage 57 controlled by the solenoid valve 12 and an output of the secondary pressure control valve 28 controlled by the control pressure of the solenoid valve 12, that is, the secondary pressure is supplied upstream. Solenoid valve 11 as pressure
The oil passage 80 controlled by the control unit is guided to control the pressure of the oil passage 68 as the primary pressure. Therefore, as a result, the primary pressure is configured to change by a predetermined function depending on the value of the secondary pressure.

The secondary pressure is introduced into the solenoid valve 32 through an oil passage 72 branched from an oil passage 69, and the solenoid valve 32
The output pressure of the oil passage 74 is the lock-up switching valve 3
8 and a pressure chamber of the neutral control valve 5 via an oil passage 47. As a result, the solenoid valve 32 can control both the neutral control valve 5 and the lockup switching valve 38. The relationship between the output pressure of the solenoid valve 32 and the lock-up and neutral control is as shown in FIG. 4, after the neutral control valve 5 is ready to start, the front or rear clutch is engaged, and the vehicle is in a running state. It is confirmed that a condition such as a certain vehicle speed is satisfied, and lock-up is controlled.

The pressure in the oil passage 74, which is the output pressure of the solenoid valve 32, is introduced via the oil passage 75 to the left side of the lock-up switching valve 38 in the drawing. On the other hand, the pressure of the oil passage 69 as a secondary pressure is introduced to the right side of the lock-up control valve 38 in the figure. When the solenoid valve 32 is almost fully opened, the pressure in the oil passage 75 is the secondary pressure,
The lock-up switching valve 38 is at the position shown in FIG. At this time, the secondary pressure passes through the oil passage 73, passes through the lock-up switching valve 38, passes through the oil passage 78, and is introduced to the left side of the lock-up clutch 41 in the drawing.
After passing through the torque converter 40, it passes through the lock-up switching valve 38 via the oil passage 79, is cooled via the oil cooler 33 via the oil passage 76, and is then drained.

When the pressure in the oil passage 74, which is the output pressure of the solenoid valve 32, is reduced, the pressure in the chamber on the left side of the lock-up switching valve 38 decreases, and the lock-up switching valve 38 moves to the left. At this time, the secondary pressure is introduced into the oil passage 79, and the output pressure of the solenoid valve 32 is introduced into the lock-up clutch 41 on the left side in the figure. At this time, the lock-up clutch 41 is slightly engaged, and by gradually changing the output pressure of the solenoid valve 32 from this state, the lock-up slip state can be controlled as shown in FIG. By setting to zero, it is possible to completely lock up.

As described above, all of the speed ratio of the CVT, belt tension, lock-up slip, and starting clutch can be controlled by this hydraulic circuit. Here, the solenoid valve 12
The secondary pressure is controlled, which roughly corresponds to controlling the belt tension. Therefore, if the solenoid valve 12 fails on the low pressure side, the CVT can transmit only a very small torque such as idling, and the vehicle virtually cannot run.

In this embodiment, the output pressure of the solenoid valve 12 is introduced into the right-hand chamber of the fail-safe valve 13 in the drawing. If the output pressure of the solenoid valve 12 falls below a specified value and the solenoid valve 12 fails, the fail-safe valve 13 switches from the illustrated position to the right position, and the solenoid valves 12 and 11 are connected to the oil passages 57 and 80.
Are communicated with each other in the oil passage 55 and the oil passage 51 which bypass the oil passage. As a result, the primary pressure and the secondary pressure are controlled to the maximum values, so that a large torque can be transmitted. Therefore, at the time of a failure, it is possible to secure the belt tension that does not substantially hinder the actual traveling, and it is possible to secure the minimum traveling function.

According to the present invention, a mechanical fail-safe valve is provided in a control device for electronically controlling the gear ratio and belt tension of a continuously variable transmission. Therefore, when the electronic control fails, a simple and low-cost configuration is used. The limited running function can be secured.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram showing a hydraulic control device for a continuously variable transmission according to one embodiment of the present invention.

FIG. 2 is an output system diagram of a manual valve according to one embodiment of the present invention.

FIG. 3 is a pressure characteristic diagram showing a relationship among a line pressure, a secondary pressure, and a primary pressure according to one embodiment of the present invention.

FIG. 4 is a graph showing output characteristics of the solenoid valve according to the embodiment of the present invention and pressure characteristics of lock-up and neutral control.

FIG. 5 is a schematic configuration diagram showing a power transmission mechanism of the continuously variable transmission according to one embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 shift lever 2 manual valve 3 prime mover 4 forward / reverse switching mechanism 5 neutral control valve 6 front clutch 7 rear clutch 8 hydraulic pump 9 pressure reducing valve 11 electromagnetic control valve (first pressure generating means) 12 electromagnetic control valve (second pressure generating means) 13) fail-safe valve (bypass valve) 14 shuttle valve 15 transmission belt 17 line pressure control valve 19 primary pressure control valve (first pressure generating means) 28 secondary pressure control valve (second pressure generating means) 32 solenoid valve 33 oil cooler 34 Secondary Pulley (Second Pulley) 34a Secondary Pulley Cylinder Chamber 35 Primary Pulley (First Pulley) 35a Primary Pulley Cylinder Chamber 38 Lock-Up Switching Valve 81 Output Shaft 82 Rotating Shaft 83 Drive Shaft 84 Follower Shaft 85 Differential Mechanism

Claims (3)

[Claims] A first pulley connected to a drive shaft; a second pulley connected to a driven shaft; a transmission belt wound around the first pulley and the second pulley to transmit power; A first and a second piston for controlling a pinching force of the transmission belt between the first and second pulleys, and changing the winding diameters of the first and second pulleys of the transmission belt to form the drive shaft and the driven shaft; A continuously variable transmission that controls a speed ratio of the transmission belt and a tension of the transmission belt; a first pressure generating unit that generates a first pressure that is adjusted according to a torque input from the drive shaft; A second pressure generating means for generating a second pressure adjusted according to a target value of: a bypass valve which bypasses the first and second pressure generating means and supplies pressure to the first and second pistons; And the second pressure is predetermined When it becomes lower, the continuously variable transmission control device and supplying the pressure to said first and second pistons by the bypass valve. 2. The bypass valve according to claim 1, wherein the transmission belt clamping force of the first pulley and the transmission belt clamping force of the second pulley are set to be the same. 3. The continuously variable transmission control device according to claim 1. 3. The first and second pressure generating means are pilot-type pressure control valves, and the bypass valve bypasses a pilot valve of the first and second pressure generating means. 3. The continuously variable transmission control device according to claim 1, wherein a pressure is supplied to a main valve of the second pressure generating means.