JPH11182666A - Hydraulic control device of belt type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent belt slip and a decrease in durability even if a linear solenoid valve controlling the pilot pressure of a belt-pressing hydraulic control valve has failed. SOLUTION: When the failure of a linear solenoid valve controlling the pilot pressure of a belt-pressing hydraulic control valve is detected, the pilot pressure of the belt-pressing hydraulic control valve is switched from the controlled pressure of the linear solenoid valve so that the clutch pressure of a forward/reverse switch mechanism is used. Using the control pressures of speed- increasing and speed-reducing solenoid valves which control speed-increasing and speed-reducing flow control valves, the pilot pressure is switched only when the solenoid valves are both turned on.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic control device for a belt-type continuously variable transmission.

[0002]

2. Description of the Related Art For example, Japanese Patent Application Laid-Open No. 58-203260 discloses a conventional hydraulic control device for a belt-type continuously variable transmission. It has a forward / reverse switching mechanism,
A belt-type continuously variable transmission having a variable effective pulley around which a transmission belt is wound, and having a flow control valve that can be switched to two positions, a speed increasing side and a decelerating side, according to the operation of an electromagnetic valve. doing.

The variable pulleys on the input shaft side and the output shaft side of the clutch of the forward / reverse switching mechanism and the continuously variable transmission portion of the continuously variable transmission are driven by hydraulic pressure. Clutch pressure for engaging the clutch is supplied to the clutch of the forward / reverse switching mechanism, and the line pressure supplied from the hydraulic pump is adjusted and supplied to the input shaft cylinder that controls the variable pulley of the input shaft. At the same time, the hydraulic pressure is discharged from the cylinder, and the hydraulic pressure of the input shaft cylinder is controlled to a required hydraulic pressure according to the shift state of the continuously variable transmission.

On the other hand, the output shaft cylinder for controlling the variable pulley of the output shaft is constantly supplied with a hydraulic pressure necessary to secure a belt pressing force that does not cause the transmission belt to slip.
The output shaft side variable pulley, the output shaft cylinder and the like constitute a belt pressing mechanism.

[0005] It is known that the hydraulic pressure for controlling the belt pressing mechanism is supplied from a belt pressing hydraulic control valve, and the pilot pressure of the belt pressing hydraulic control valve is adjusted by a linear solenoid valve.

In recent years, more precise control has been required as compared with the prior art. As for the flow control valves, two flow control valves used for increasing speed and deceleration are used, respectively.
A device having two solenoid valves for increasing the speed and reducing the speed for generating a control pressure introduced into each flow control valve has been developed.

[0007]

However, in the case of adjusting the hydraulic pressure for applying the belt pressing force of the belt pressing mechanism with a linear solenoid valve, if the linear solenoid valve breaks down, it cannot be backed up and the output shaft is temporarily stopped. If a failure occurs on the low pressure side within the control range of the hydraulic pressure in the cylinder, the belt pressing force will be insufficient and belt slippage will occur. May be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. Even if a linear solenoid valve for controlling the pilot pressure of a hydraulic pressure control valve for a belt breaks down, belt slippage and durability may be reduced. It is an object of the present invention to provide a hydraulic control device for a belt-type continuously variable transmission that does not have a belt.

[0009]

The invention according to claim 1 is
As shown in FIG. 1, a clutch pressure control valve for controlling a clutch pressure of a clutch of a forward / reverse switching mechanism, a belt pressing hydraulic control valve for controlling a belt pressing mechanism of a belt type continuously variable transmission, and a pilot pressure thereof. In a hydraulic control device for a belt-type continuously variable transmission including a linear solenoid valve that adjusts pressure, means for detecting a failure of the linear solenoid valve, and when the failure of the linear solenoid valve is detected, presses the belt. Means for switching the pilot pressure of the hydraulic control valve from the controlled pressure of the linear solenoid valve to the clutch pressure of the clutch pressure control valve,
This has solved the above-mentioned problem.

According to the present invention, even if the linear solenoid valve for controlling the pilot pressure of the belt pressing hydraulic control valve fails, the clutch pressure of the clutch pressure control valve is used instead. Appropriate control can be performed, and belt slippage and belt breakage can be prevented.

If the continuously variable transmission has (already) a flow rate control valve for speed increase and deceleration and a solenoid valve for controlling the same, when the linear solenoid valve fails, the increase Only when both the speed-up and deceleration solenoid valves that control the speed control and deceleration flow control valves, respectively, are ON,
When the pilot pressure of the belt pressing hydraulic control valve is switched from the controlled pressure of the linear solenoid valve to the clutch pressure of the clutch pressure control valve using the controlled pressures of the two control valves, a new solenoid valve is provided. The above problem can be solved without any problem.

[0012]

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

FIG. 2 is a configuration diagram schematically showing the periphery of a belt-type continuously variable transmission to which the present invention is applied.

In FIG. 2, the rotation of the engine (not shown) is transmitted from the crankshaft 22 to the torque converter output shaft 24 via the torque converter 10. Thereafter, the rotation of the engine is transmitted to the axle shaft 20 via the forward / reverse switching device 12, the belt-type continuously variable transmission (CVT) 14, the reduction gear device 16, and the differential gear device 18.

The forward / reverse switching device 12 is provided concentrically between the torque converter output shaft 24 and the input shaft 26 of the CVT 14, and switches between a forward gear and a reverse gear. The rotation of the torque converter output shaft 24 is transmitted to the input shaft 26 of the CVT 14 by the forward / reverse switching device 12.

The torque converter 10 includes a pump impeller 10a, a turbine runner 10b, a stator 10c, and a lock-up clutch 10d. The pump impeller 10a is connected to a crankshaft 22 of the engine. The turbine runner 10b is connected to the torque converter output shaft 24. The rotation of the engine starts from the crankshaft 22 through the pump impeller 10a and the turbine runner 10b.
Through the torque converter output shaft 24.

The back side 10 of the lock-up clutch 10d
e, the lock-up clutch 10d is engaged with the front cover 10f of the torque converter 10, and the rotation of the crankshaft 22 causes the lock-up clutch 10d to rotate.
The torque is directly transmitted to the torque converter output shaft 24 via d. When the hydraulic pressure on the front side 10g of the lock-up clutch 10d is increased, the lock-up clutch 10d is separated from the front cover 10f, and the lock-up is released.

The forward / reverse switching device 12 is configured as a so-called double planetary type, and includes a sun gear 12s, a carrier 12c, and a ring gear 12r. Sun gear 12
s is connected to the torque converter output shaft 24.
Each carrier 12c is connected to a torque converter output shaft 24 via a forward clutch 28, and a CVT 1
4 input shafts 26. Also, the ring gear 12
r is connected to the reverse brake 12b.

The CVT 14 includes a primary pulley 30, a secondary pulley 32, and an endless belt 34 having a V-shaped cross section.
The rotation introduced to 0 is transmitted from the secondary pulley 32 to the output shaft 36 of the CVT 14 via the endless belt 34.

The primary pulley 30 and the secondary pulley 32 are respectively movable half pulleys 30a and 32a movable in the axial direction, and fixed pulley halves 30b and 30b.
2b. The movable pulley half 30a of the primary pulley 30 is a hydraulic cylinder (input shaft cylinder).
Due to the hydraulic pressure (input shaft cylinder pressure) Pin introduced to 30c, the movable pulley half 32 of the secondary pulley 32
a moves in the axial direction by the hydraulic pressure (output shaft cylinder pressure) Pout introduced into the hydraulic cylinder (output shaft cylinder) 32c. As a result, the radius of rotation of the portion where the endless belt 34 is wound around the primary pulley 30 and the secondary pulley 32 changes, and the speed ratio of the CVT 14 changes.

The forward clutch 28 and the reverse brake 12b of the forward / reverse switching device 12 and the input shaft cylinder 3
0c, hydraulic pressure Pin, P introduced into the output shaft cylinder 32c
out is controlled by the hydraulic control device 40. The hydraulic control device 40 is controlled by a computer 42.
The computer 42 determines whether to maintain the speed ratio of the CVT 14, increase the speed, or reduce the speed based on signals from the various sensor groups 44.
Further, the computer 42 detects a failure of a linear solenoid valve (described later) by a known failure detection method based on signals from the various sensor groups 44.

FIG. 3 shows a hydraulic circuit configuration of the hydraulic control device 40 according to the first embodiment of the present invention.

In the hydraulic circuit shown in FIG.
4 will be described.

The hydraulic pump 52 sucks in the hydraulic oil which has flowed back into the oil tank 54 through the return oil passage R2 through a strainer (not shown), and discharges it to the oil passage R1. The oil passage R1 is provided with a relief valve 56 for preventing abnormal pressure rise above a predetermined pressure.

The line pressure PL1 in the oil passage R1 is controlled by a line pressure control valve 58. The line pressure PL1 is applied to the port 60b of the belt pressing hydraulic control valve 60 via the oil passage R1.
Led to. The belt pressing oil pressure control valve 60 controls the line pressure PL1 depending on the transmission torque of the endless belt 34 to reduce the pressure to a minimum oil pressure necessary for preventing belt slip, and to reduce the belt pressing oil pressure (output). Shaft cylinder pressure)
As Pout, the secondary pulley 32 is connected via the oil passage R3.
To the output shaft cylinder 32c of the movable side pulley half 32a.

A linear solenoid valve 72 is provided to control the line pressure control valve 58 and the belt pressing hydraulic control valve 60. The output pressure (controlled pressure) Pe output from the linear solenoid valve 72 passes from the oil passage R8 to the pilot port 58a of the belt pressure hydraulic control valve 60 through the safety valve 74 and the oil passage R9, respectively. And 60a.

The upper limit of the output pressure Pe of the linear solenoid valve 72 is switched between two stages by a cutback valve 76. The linear solenoid valve 72 has two feedback ports 72a and 72b. When only the feedback port 72a is used, the linear solenoid valve 7
The upper limit of the output pressure Pe is high, and the upper limit is controlled to be low when both the feedback ports 72a and 72b are used. This switching is performed by controlling the hydraulic pressure introduced into the port 76 a of the cutback valve 76 on / off by the solenoid valve 78.

The shift control unit 50 controls the input shaft cylinder pressure Pin
Control. The shift control unit 50 includes a speed increasing flow control valve 62.
It mainly comprises a deceleration flow control valve 64, a speed increasing solenoid valve 66 and a deceleration solenoid valve 68.

The speed increasing flow control valve 62 receives the supply of the line pressure PL1 through the oil passage R4, controls the supply thereof, and
Through the input shaft cylinder 30c of the primary pulley 30
Supply to The deceleration flow control valve 64 reduces the input shaft cylinder pressure Pin through an oil passage R6 branched from the oil passage R5. Flow control valve 62 for speed increase and flow control valve 64 for deceleration
Are controlled by a speed increasing solenoid valve 66 and a deceleration solenoid valve 68, respectively.

The oil passage R1 is provided with a constant pressure control valve 70 for adjusting the line pressure PL1 to a constant oil pressure and outputting the adjusted oil pressure. The oil pressure maintained constant by the constant pressure control valve 70 is transmitted through the oil passage R7 to the speed increasing solenoid valve 6.
6 and the electromagnetic valve 68 for deceleration. Speed increasing solenoid valve 66
When the deceleration solenoid valve 68 is on, the hydraulic pressure is introduced as a control pressure into the speed-up flow control valve 62 and the deceleration flow control valve 64, respectively.

Next, a portion related to the control of the forward / reverse switching device 12 will be described.

The part related to the control of the forward / reverse switching device 12 includes:
A clutch pressure control valve 80 for controlling the clutch pressure Pc supplied to the forward clutch 28 and the reverse brake 12b of the forward / reverse switching device 12, and a manual valve for distributing the clutch pressure Pc to the forward clutch 28 and the reverse brake 12b 82 and two accumulators 84,86.

The clutch pressure control valve 80 is controlled by a linear solenoid 88. The linear solenoid 88 is
With the output pressure of the constant pressure control valve 70 as a base pressure, the output pressure is controlled to an output pressure between atmospheric pressure and a constant pressure, and is introduced into the clutch pressure control valve 80. The clutch pressure Pc output from the clutch pressure control valve 80 is guided to the port 82a of the manual valve 82 through the oil passage R10.

The position of the spool 82s of the manual valve 82 is switched by a driver's shift operation.
The port 82a communicates with the port 82b,
c, or communication with either of them is interrupted. When the shift position is in the D range, the port 82
a communicates with the port 82c, and the clutch pressure Pc is sent to the forward clutch 28 through the oil passage R11. or,
When the shift position is in the R range, the port 82a communicates with the port 82b, and the clutch pressure Pc is sent to the reverse brake 12b through the oil passage R12.

Next, a part related to the control of the lock-up clutch 10d will be described.

The base pressure of the lock-up control (the base pressure of the hydraulic pressure introduced to the rear side 10e and the front side 10g of the lock-up clutch 10d) is a secondary pressure control valve 90 provided on the drain side of the line pressure control valve 58. Is controlled by

This control pressure is guided to a lock-up relay valve 92 and a lock-up control valve 94 via an oil passage R13. Lock-up relay valve 92
Is on (right side of the figure) and off (left side of the figure) is port 92a
Is controlled by the signal pressure of the solenoid valve 78 guided to the valve.

The lock-up relay valve 92 is in a lock-up engagement when on, and is in a lock-up release when off. The lock-up control valve 94 is
Controlled by the signal pressure of the solenoid valve 96, when the lock-up is engaged, the rear side 1 of the lock-up clutch 10d
By controlling the oil pressure of 0e, smooth engagement / disengagement and slip control are performed.

Next, a part related to control of each lubricating part will be described.

A cooler pressure control valve 98 is provided via a throttle in an oil passage R14 for sending oil pressure to the rear side 10e of the lock-up clutch 10d at the time of lock-up engagement. Then, the oil pressure controlled by the cooler pressure control valve 98 is transferred to the oil passage R15.
To the cooler 99, and further supplies hydraulic pressure to each lubricating unit.

Finally, the pilot pressure of the belt pressing hydraulic control valve 60 according to the present invention is
The configuration of the portion that switches from the output pressure Pe to the clutch pressure Pc will be described.

As described above, the belt pressing oil pressure Pout obtained by adjusting the line pressure PL1 by the belt pressing oil pressure control valve 60 is supplied to the output shaft cylinder 32c through the oil passage R3.

The belt pressing hydraulic control valve 60 is controlled by a linear solenoid valve 72. The output pressure Pe of the linear solenoid valve 72 is switched in two stages by a cut-back valve 76, guided to the port 74a of the safety valve 74 from the oil passage R8, and from the port 74b to the oil passage R
9 is introduced to the pilot port 60a of the belt pressing hydraulic control valve 60. The output pressure Pe is also introduced into a pilot port 58a of the line pressure control valve 58.

The clutch pressure Pc of the clutch pressure control valve 80 is introduced into a port 74c of the safety valve 74 via an oil passage R16. The safety valve 74 is
The state in which the ports 74a and 74b communicate with each other and the port 74
The state of communication between c and 74b is switched by the action of the solenoid valve 100. By this switching, the port 74a is connected to the pilot port 60a of the belt pressing hydraulic control valve 60.
When the ports 74c and 74b communicate with each other, the output pressure Pe of the linear solenoid valve 72 is introduced. When the ports 74c and 74b communicate with each other, the clutch pressure Pc of the clutch pressure control valve 80 is introduced.

By the way, if the linear solenoid valve 72 is out of order, the clutch pressure Pc which has not been specifically treated is substituted as it is, if the clutch pressure Pc is lower than the required oil pressure, the belt slip is not necessarily completely completed. Can not be prevented.

Therefore, in order to prevent this, in the above embodiment, the clutch pressure Pc is generated in advance in accordance with the hydraulic pressure required for the input shaft cylinder pressure Pin in consideration of the fail-safe according to the present invention. It is. That is, the clutch pressure Pc is controlled by controlling the control current IPc of the linear solenoid 88 for controlling the clutch pressure control valve 80 in accordance with the required clutch pressure Pc 'or the required input shaft cylinder pressure Pin'.

FIG. 6 shows the control current IPc and the clutch pressure P
The relationship with c is shown. In the figure, a represents the range of the required clutch pressure Pc ', and b represents the range of the required input shaft cylinder pressure Pin'. When the required clutch pressure Pc 'is higher than the required input shaft cylinder pressure Pin', the clutch pressure Pc is controlled by controlling the control current IPc according to the required clutch pressure Pc '. If the required input shaft cylinder pressure Pin 'is higher than the required clutch pressure Pc', the control current I
The clutch pressure Pc is controlled by controlling Pc according to the required input shaft cylinder pressure Pin '. As a result, the clutch pressure Pc is controlled within a range in which the necessary input shaft cylinder pressure Pin 'shown in FIG. Required belt pressing hydraulic pressure Pout
′ Is not higher than the required input shaft cylinder pressure Pin ′, and as a result, belt slip can always be prevented.

The operation of the first embodiment will be described below.

As described above, the output pressure P of the linear solenoid valve 72 is connected to the port 74a of the safety valve 74.
e is led, and the clutch pressure Pc of the clutch pressure control valve 78 is led to the port 74c.

Normally, the safety valve 74 is turned off (the left side in the figure), the port 74a communicates with the port 74b, and the output pressure Pe of the linear solenoid valve 72 is applied to the belt pressing hydraulic control valve 60 via the oil passage R8. Pilot port 6
0a, and the belt pressing oil pressure Pout is controlled by the output pressure Pe.

When the computer 42 detects that the linear solenoid valve 72 has failed by a signal from the various sensor groups 44, the solenoid valve 100 is opened.
The safety valve 74 is switched and turned on (right side in the figure).

As a result, the port 74a and the port 74b of the safety valve 74 are shut off, the port 74c communicates with the port 74b, and the output pressure P of the linear solenoid valve 72 increases.
Instead of e, the clutch pressure Pc of the clutch pressure control valve 78 is introduced from the port 74c to the pilot port 60a of the belt pressing hydraulic control valve 60 via the oil passage R9, so that the belt pressing hydraulic pressure Pout can be controlled.

Accordingly, the belt pressing oil pressure Pout does not become too low or too high, and it is possible to prevent the belt from slipping and the durability from being lowered.

Next, a second embodiment of the present invention will be described.

In the second embodiment, the solenoid valve 100 in the first embodiment shown in FIG. 3 is eliminated, the number of ports of the safety valve 74 is increased, and the speed increasing and deceleration solenoid valves 66 are provided.
The output pressure (controlled pressure) 68 is guided to the safety valve 74, whereby the safety valve 74 is switched.

FIG. 4 shows a hydraulic circuit configuration of the hydraulic control device according to the second embodiment, and FIG. 5 is an enlarged view of the periphery of the safety valve 174.

In FIG. 5, the output pressure Pe of the linear solenoid valve 172 is led to a port 174a of the safety valve 174, and the clutch pressure control valve 1 is connected to a port 174c.
A clutch pressure Pc of 80 is led. The port 174b of the safety valve 174 and the pilot port 160a of the hydraulic pressure control valve 160 communicate with each other.

The safety valve 174 further has two ports 174e and 174f. Port 174d
The output pressure of the speed increasing solenoid valve 166 is introduced to
The output pressure of the deceleration solenoid valve 168 is introduced to 74e.

The spring 174f of the safety valve 174
Urges the spool 174s downward in the figure, and only when the output pressure of the speed increasing and deceleration solenoid valves 166 and 168 is introduced into each of the ports 174d and 174e, the spool 174s The spring force of the spring 174f is set so as to move upward.

When it is detected that the linear solenoid valve 172 has failed, in order to prevent sudden increase or sudden deceleration,
In order to fix the gear ratio at that time, the speed increasing solenoid valve 166 is used.
And the deceleration solenoid valve 168 are both turned on. As a result, the ports 174d and 17
The controlled pressure of each of the solenoid valves 166 and 168 is introduced into each of the valves 4e, 4e, and the spool 174s is pushed upward, so that the ports 174c and 174b communicate with each other.

As a result, even if the linear solenoid valve 172 fails, the clutch pressure Pc of the clutch pressure control valve 180 is reduced by the pilot port 160 of the belt pressing hydraulic control valve 160.
a, and the belt pressing oil pressure Pout is appropriately controlled.

In this case, as in the first embodiment, the solenoid valve 1
Since 00 is not required, belt slippage and reduction in durability can be easily prevented with a simple configuration.

For the other components, the same components as those of the first embodiment shown in FIG.

The speed-up and speed-down solenoid valves 166, 1
When both 68 are on, the speed change in the speed change mechanism is fixed, so that the driver can detect the abnormality and take an appropriate countermeasure.

[0065]

As described above, according to the present invention,
Even if the linear solenoid valve that adjusts the pilot pressure of the belt pressing hydraulic control valve that controls the belt pressing mechanism of the belt-type continuously variable transmission fails, the clutch pressure of the forward / reverse switching mechanism is used as the pilot pressure. It is now possible to prevent belt slippage and belt destruction.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is a configuration diagram schematically showing the periphery of a belt-type continuously variable transmission to which the present invention is applied;

FIG. 3 is a hydraulic circuit diagram schematically showing a hydraulic control device according to the first embodiment of the present invention.

FIG. 4 is a hydraulic circuit diagram schematically showing a hydraulic control device according to a second embodiment of the present invention.

FIG. 5 is an enlarged view around the safety valve in FIG. 4;

FIG. 6 is a diagram showing a relationship between a clutch pressure and a control current of a linear solenoid that controls a clutch pressure control valve.

[Description of Signs] 10 Torque converter 12 Forward / reverse switching device 14 Belt-type continuously variable transmission (CVT) 16 Reduction gear device 18 Differential gear device 20 Axle shaft 22 Crank shaft 24 Torque converter output Shaft 26 Input shaft 28 Forward clutch 30 Primary pulley 32 Secondary pulley 34 Endless belt 36 Output shaft 40 Hydraulic controller 42 Computer 44 Sensor group 52, 152 Hydraulic pump 58, 158 Line Pressure control valves 60, 160 ... Belt pressing hydraulic control valves 62, 162 ... Speed increasing flow control valves 64, 164 ... Speed decreasing flow control valves 66, 166 ... Speed increasing solenoid valves 68, 168 ... Deceleration solenoid valves 70, 170: Constant pressure control valve 72, 172: Linear solenoid valve 74, 174: Safety valve 80, 180 ... clutch pressure control valve 100 ... solenoid valve

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masafumi Nishigaya 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (2)

[Claims] 1. A clutch pressure control valve for controlling a clutch pressure of a clutch of a forward / reverse switching mechanism, a belt pressing hydraulic control valve for controlling a belt pressing mechanism of a belt type continuously variable transmission, and a linear solenoid for adjusting its pilot pressure A hydraulic control device for a belt-type continuously variable transmission, comprising: a valve for detecting a failure of the linear solenoid valve; and a pilot for the belt pressing hydraulic control valve when the failure of the linear solenoid valve is detected. Means for switching the pressure from the controlled pressure of the linear solenoid valve to the clutch pressure of the clutch pressure control valve. A hydraulic control device for a belt-type continuously variable transmission, comprising: 2. The method according to claim 1, further comprising: two flow control valves respectively used for speed increase and deceleration; and a speed increase device for generating a control pressure introduced into each flow control valve.
Two solenoid valves for deceleration are provided, and the means for switching the pilot pressure is controlled by the controlled pressures of the two solenoid valves only when the two solenoid valves for speed-up and deceleration are both on. A hydraulic control device for a belt-type continuously variable transmission, wherein the switching is performed.