JPH0699754A - Oil pressure control unit for vehicle - Google Patents

Abstract

PURPOSE:To prevent lowering of a fail safe pressure when a motor control system is normal even during system fail. CONSTITUTION:In first constitution, a constant pressure holding control means (i) is provided for outputting a control command, through which a constant control pressure is held, to a drive current applying means (f) to apply a current with a dither on a solenoid (d) when it is detected that a valve operation control system is normal during system fail. In constitution of fail safe, a motor control continuing means (m) is provided for outputting a command, through which motor drive control is continued, to a motor drive control means (j) when it is decided that a motor control system is normal during system fail.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front and rear wheel drive torque distribution control system for finely controlling the torque distribution of front and rear wheels according to the magnitude of the clutch engagement force by the control pressure supplied to a hydraulic multi-plate friction clutch. The present invention relates to a vehicle hydraulic control unit.

[0002]

2. Description of the Related Art Conventionally, as a proportional electromagnetic pressure reducing valve used in a vehicle hydraulic control unit, for example, the one shown in FIG. 7 is generally known.

This proportional electromagnetic pressure reducing valve has a spool and a solenoid, and by applying a solenoid force generated in proportion to the solenoid current value to the spool in a direction to connect the supply pressure port and the control pressure port, the oil is reduced. The supply pressure from the pump is used as the control pressure according to the solenoid current value.

[0004]

However, in the above-mentioned conventional proportional solenoid pressure reducing valve, when the current value to the solenoid is set to zero at the time of system failure, the solenoid force on the spool disappears and the spring force of the return spring causes the spool to move. Since the control pressure port and drain port are fixed at the communicating position, the control system to which the hydraulic control unit using this proportional electromagnetic pressure reducing valve is applied is
If there is a request to keep a certain control pressure applied during a failure, the request cannot be met.

Therefore, the present applicant has filed Japanese Patent Application No. 4-1264.
In the specification and drawings of No. 08 (filed on May 19, 1992), a fail-safe solenoid and a fail-safe spring are added to the conventional proportional electromagnetic pressure reducing valve, so that all fail regardless of the cause of sensor failure or disconnection. Sometimes
We proposed a proportional electromagnetic pressure reducing valve with a fail-safe function that applies fail-safe spring force to the spool to obtain a fail-safe pressure at a constant pressure.

However, even if this proportional electromagnetic pressure reducing valve with a fail-safe function is used, there are problems as described below.

(1) Since the pressure is generated by the fail-safe spring force, the hydraulic control accuracy is poor, and the drive torque distribution performance at the time of failure is easily affected by temperature conditions and the like.

For example, when the oil temperature is low, the spool moves badly due to sticking, etc., so that the hydraulic pressure is not stable and the pressure fluctuates at intervals of 100 seconds to 200 seconds as shown in FIG. At times, the four-wheel drive performance may be insufficient, and when the pressure is higher than the fail-safe pressure, the tight corner brake and ABS performance may be affected.

(2) If the motor that drives the oil pump is stopped at the time of failure, the fail-safe pressure is held for a short time due to oil leakage from the spool.

That is, as shown in FIG. 9, the fail-safe pressure is generated immediately after the occurrence of the fail, but as time elapses from that time, the oil pressure gradually decreases due to the oil leak, and the fail-safe pressure is generated. The purpose of keeping pressure is not achieved.

On the other hand, for example, in the case of the front and rear wheel drive torque distribution control system, the hydraulic multi-disc friction clutch is released at the time of failure in order to keep a certain control pressure applied at the time of failure. When the drive torque distribution to the front wheels is set to zero, it becomes an ordinary rear wheel drive vehicle, and the significance of installing the drive torque distribution control system is completely eliminated.
If the hydraulic multi-plate friction clutch is engaged to the extent that tight corner brakes are not generated and drive torque is distributed to the front wheels, traction performance and stack escape characteristics will be improved, and as a four-wheel drive vehicle at the time of failure. It is possible to achieve both the effect and the tight corner brake prevention, and there is a demand to keep a certain control pressure applied during a failure.

The present invention has been made by paying attention to the above-mentioned requirements and problems, and in a vehicle hydraulic control unit having an oil pump motor which is drive-controlled and a proportional electromagnetic pressure reducing valve, when a system failure occurs. Even when the valve operation control system of the proportional electromagnetic pressure reducing valve is normal, the first object is to obtain a constant fail-safe pressure with suppressed hydraulic pressure fluctuation with high control accuracy.

In addition to the first problem described above, a second problem is to prevent the fail-safe pressure from decreasing even when the motor control system of the oil pump motor is normal even during system failure.

[0014]

In order to solve the above-mentioned first problem, in the vehicle hydraulic control unit according to the first aspect of the present invention, the valve operation control system fail judging means performs the valve operation even when the system failure is judged. When it is determined that the operation control system is normal, a constant pressure holding control means is provided to output a control command for holding a constant control pressure to the drive current applying means, and a dithered current is supplied to the solenoid of the proportional solenoid pressure reducing valve. Was applied to obtain a constant control pressure.

That is, as shown in the claim correspondence diagram of FIG. 1, an oil pump b driven by an electric motor a.
And a proportional electromagnetic pressure reducing valve e having a spool c and a solenoid d and having a supply pressure from the oil pump b as a control pressure according to a solenoid current value, and a drive current for applying a dithered current to the solenoid d. An application means f, a system failure determination means g for determining a failure of a control system to which the hydraulic control unit is applied, a valve operation control system failure determination means h for determining whether the current control of the solenoid d is possible, Despite the failure judgment by the system failure judgment means g, when the valve operation control system failure judgment means h judges that the valve operation control system is normal, the drive current application means f is kept constant. And a constant pressure holding control means i which outputs a control command for holding the control pressure.

In order to solve the above-mentioned second problem, in the vehicle hydraulic control unit according to the second aspect, the motor control system is judged to be normal by the motor control system failure judgment means even when the system failure is judged. When judged,
Motor control continuation means for outputting a command for continuing motor drive control to the motor drive control means is provided.

That is, as shown in the claim correspondence diagram of FIG. 1, in the vehicle hydraulic control unit according to claim 1, motor drive control means for controlling the motor drive current by monitoring the pump discharge pressure of the electric motor a. j, the motor control system failure determination means k for determining whether or not the motor control of the electric motor a is possible, and the motor control system failure determination means k, even though the system failure determination means g determines failure. When it is judged that the motor control system is normal by means of the above, it is characterized by further comprising motor control continuation means m for outputting a command for continuing the motor drive control to the motor drive control means j.

[0018]

The operation of the present invention will be described.

When the system fail judgment means g judges the failure of the control system to which this hydraulic control unit is applied, the valve operation control system failure judgment means h controls the current control of the solenoid d of the proportional electromagnetic pressure reducing valve e. It is judged whether it is possible. Then, in the constant pressure holding control means i, when the valve operation control system fail judgment means h judges that the valve operation control system is normal despite the fact that the system failure judgment means g judges the failure, the solenoid is operated. A control command for maintaining a constant control pressure is output to the drive current applying unit f that applies a dithered current to d.

Therefore, when the valve operation control system is normal even when the system fails, the proportional electromagnetic pressure reducing valve e
By applying the dithered current to the solenoid d, the smooth operation of the spool c is ensured even when the temperature condition changes, and a constant control pressure is obtained with stable high control accuracy.

The operation of the invention according to claim 2 will be described.

When the system failure judgment means g judges the failure of the control system to which this hydraulic control unit is applied, the motor control system failure judgment means k judges whether or not the motor control of the electric motor a is possible. It

Then, in the motor control continuation means m,
When the motor control system failure determination means k determines that the motor control system is normal even when the system failure determination means g determines the failure, the electric motor a is driven by monitoring the pump discharge pressure. A command to continue the motor drive control is output to the motor drive control means j that controls the current.

Therefore, even when the system fails, the motor drive control is continued when the motor control system is normal, and the spool c of the proportional electromagnetic pressure reducing valve e is continued.
Even if there is a leak of oil, the amount of oil is replenished for that amount, and it is possible to prevent a pressure drop due to the passage of time of a constant control pressure given at the time of fail.

[0025]

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

First, the structure will be described.

FIG. 2 is a front / rear wheel drive torque distribution control system diagram of the rear wheel drive base to which the vehicle hydraulic control unit according to the embodiment of the present invention is applied.

In FIG. 2, 1 is an engine, 2 is a transmission, 3 is a rear propeller shaft, 4 is a rear differential, 5 and 6 are rear drive shafts,
7, 8 are rear wheels, 9 is transfer, 10 is front propeller shaft, 11 is front differential, 1
Reference numerals 2 and 13 are front drive shafts, and 14 and 15 are front wheels.

The transfer 9 has a built-in wet multi-plate clutch 16 in which the driving torque distribution to the front wheels 14 and 15 is determined by the magnitude of the fastening force.

In the wet multi-plate clutch 16, the fastening force is controlled by the control pressure generated by the hydraulic unit 18 by the control current from the ETS control unit 17, and the ETS control unit 17 includes the right front wheel rotation sensor 19. , Left front wheel rotation sensor 20, right rear wheel rotation sensor 21, left rear wheel rotation sensor 22, lateral acceleration sensor 23
Sensor information from, etc. is input.

In order to improve the accelerator controllability and limit predictability during turning acceleration, the control law basically increases the drive torque distribution to the front wheels in response to the front-rear wheel rotational speed difference, thereby turning and road friction. In order to ensure the optimum control regardless of the change in the coefficient, the control gain is made smaller as the lateral acceleration becomes larger.

FIG. 3 is a diagram showing the hydraulic unit 18 of the embodiment.

In FIG. 3, the hydraulic unit 18 includes an electric motor 24, an oil pump 25, an accumulator 26,
A proportional electromagnetic pressure reducing valve 27 with a fail-safe function, a pressure switch 28, a relief valve 29, a check valve 30, and an air bleeder 31 are provided, and a reservoir tank 32 provided outside is the air bleeder 31 and the suction pipe 3.
3 and the proportional electromagnetic pressure reducing valve 27 communicates with the return pipe 34. The proportional electromagnetic pressure reducing valve 27 with a fail-safe function and the piston oil chamber of the wet multi-plate clutch 16 communicate with each other through a control pressure pipe 35.

The electric motor 24 has a pressure switch 28.
ON / OFF control is performed by a command from the ETS control unit 17 based on the switch signal from the.

FIG. 4 is a sectional view showing a proportional electromagnetic pressure reducing valve 27 with a failsafe function used in the hydraulic unit 18 of the embodiment.

In FIG. 4, 36 is a spool, 37 is a housing, 38 is a feedback oil passage, 39 is a control pressure port, 40 is a supply pressure port, 41 is a drain port, 4
2 is a plate, 43 is a control solenoid coil, 44 is a control plunger, 45 is a case, 46 is a fail-safe solenoid coil, 47 is a fail-safe plunger, 4
Reference numeral 8 is a fail-safe spring, and 49 is a return spring.

The control solenoid coil 43 reduces the accumulator pressure to the control pressure by the control current i ₁ from the ETS control unit 17 when the system is normal.

The fail-safe solenoid coil 46
Prevents the spring force of the fail-safe spring 48 from acting on the spool 36 by a constant control current i ₂ from the ETS control unit 17 at a predetermined normal time, and the spring of the fail-safe spring 48 by a zero current at a predetermined fail time. The force is applied to the spool 36. For details, see Japanese Patent Application No. 4-12.
See the specification and drawings of No. 6408 (filed on May 19, 1992).

FIG. 5 is a block diagram of the fail-safe control system of the vehicle hydraulic control unit of the embodiment.

In FIG. 5, 50 is various sensor signals and 5
Reference numeral 1 is a pressure switch monitor, 52 is a harness disconnection detection monitor, 53 is a motor rotation monitor, 54 is a valve relay, 55 is a motor relay, and 56 is a battery.

Next, the operation will be described.

(Fail-safe processing operation) FIG. 6 shows ETS.
Each step will be described below with a flowchart showing the flow of the fail-safe processing operation performed by the control unit 17.

In step 60, it is judged whether or not there is a system failure (corresponding to system failure judgment means). This judgment is made, for example, by the system fail judgment circuit 17a of the ETS control unit 17 at 5
It is performed by monitoring each item described in 0 to 53 and the like.

In step 61, it is judged whether or not the valve control system can be controlled (corresponding to a valve operation control system fail judging means). This determination is made by, for example, the valve relay 54,
An energization check is performed on the control solenoid coil 43 and the fail-safe solenoid coil 46, and it is determined whether or not energization is possible without any abnormality.

Step 62 is a step to proceed when YES is determined in step 61, and the valve relay 54 is turned on.
While keeping N, the dithered current drive circuit 17b (corresponding to drive current application means) applies the dithered control current i _1C to the control solenoid coil 43 so that a constant pressure (for example, tight corner brake is not generated and the stack is generated). Control is performed to maintain a transmission torque of 5 kg · m (which corresponds to a certain level of performance) (corresponding to a constant pressure holding control means).

Step 63 is a step to proceed when NO is judged in step 61, and the valve relay 54 is turned off.
Control to F is performed.

In step 64, it is judged whether or not the motor control system can be controlled (corresponding to a motor control system fail judging means). This judgment is made by observing the switch operation on the pressure switch monitor 51 or the motor rotation monitor 53, for example.
It is carried out by checking the rotating state or checking the energization of the motor relay 55.

Step 65 is a step to proceed when YES is determined in step 64, and the motor relay 55 is turned on.
With the pressure set to N, the motor drive circuit 17c (corresponding to the motor drive control means) responds to the pressure switch 28 to turn on / off.
Normal motor control for OFF control is continued (corresponding to motor control continuation means).

Step 66 is a step to proceed when NO is judged in step 65, and the motor relay 55 is turned off.
Control to F is performed.

(When the valve control system and the motor control system fail) When the valve control system and the motor control system fail due to a cause of failure such as a wire break in the harness, in FIG. 6, step 60 → step 61 → step 63 →
The flow proceeds from step 64 to step 66, and by turning off the valve relay 54 in step 63, the current to both solenoid coils 43 and 46 is cut off, and by turning off the motor relay 66 in step 66, electric power is supplied. The rotation control of the motor 24 is stopped.

Therefore, the spool 36 of the proportional electromagnetic pressure-reducing valve 27 with fail-safe function is acted by the fail-safe spring 48, and this spring force controls the fail-safe pressure to a constant value.

Although the fail-safe pressure due to the spring force maintains a certain degree of accuracy when the oil temperature is high, it may vary due to the oil temperature as described in the prior art. With the passage of time, the spool 36
Since the pressure decreases due to the leakage from the valve, in consideration of these influences, for example, the pressure is set to a little higher than the fail-safe pressure of 5 kg / cm ² corresponding to the solenoid control.

(When the valve control system and the motor control system are normal) Although the system has failed due to a failure cause such as a sensor abnormality, when the valve control system and the motor control system are normal, step 60 → step 61 in FIG.
The flow proceeds from step 62 to step 64 to step 65. At step 62, control for maintaining the fail-safe pressure is performed by applying the dithered control current i _1C to the control solenoid coil 43. In step 65, the pressure switch 28 is turned on / off.
Normal motor control to control continues.

Therefore, the solenoid 36 according to the dithered control current i _1C acts on the spool 36 of the proportional electromagnetic pressure reducing valve 27 with the fail-safe function, and the solenoid force is stable without being affected by the oil temperature. It is controlled to a constant fail-safe pressure with high hydraulic control accuracy.
In addition, by continuing the normal motor control, even if there is a leak from the spool 36 over time, the pressure does not drop, and this constant fail-safe pressure is maintained for a long time.

(When the valve control system is normal and the motor control system fails) The valve control system is normal, but the valve relay 5
4, when the valve control system fails due to defective current supply to the control solenoid coil 43, the fail-safe solenoid coil 46, etc., the flow proceeds from step 60 to step 61 to step 63 to step 64 to step 65 in FIG. Then, the control for maintaining the fail-safe pressure is performed by applying the dithered control current i _1C to the control solenoid coil 43. In step 66, the pressure switch 28 responds to the ON / O.
Normal motor control for FF control is stopped.

Therefore, a solenoid force corresponding to the dithered control current i _1C acts on the spool 36 of the proportional electromagnetic pressure reducing valve 27 with the fail-safe function, and the solenoid force is stabilized without being affected by the oil temperature. It is controlled to a constant fail-safe pressure with high hydraulic control accuracy.
However, if the normal motor control is stopped and there is a leak from the spool 36 over time, this fail-safe pressure will gradually decrease.

(When the valve control system fails and the motor control system is normal) The motor control system is normal, but the pressure switch 2
When the motor control system fails, such as when 8 or the electric motor 24 fails, the flow proceeds in the order of step 60 → step 61 → step 63 → step 64 → step 65 in FIG.
Is turned off, the current to both solenoid coils 43 and 46 is cut off.
The normal motor control for ON / OFF control in response to is continued.

Therefore, the spool 36 of the proportional electromagnetic pressure-reducing valve 27 with fail-safe function is acted by the fail-safe spring 48, and this spring force controls the fail-safe pressure to a constant value. However, by continuing the normal motor control, even if there is a leak from the spool 36 with the lapse of time, this decrease in the fail-safe pressure is prevented, and a stable fail-safe condition is maintained when the oil temperature is high. The pressure can be obtained.

Next, the effect will be described.

(1) When it is determined that the valve control system is normal despite the system failure determination, the dithered control current i is supplied to the control solenoid coil 43.
_Since it is a device that performs control to maintain the fail-safe pressure by applying _1C , even if the system fails, when the valve control system of the proportional electromagnetic pressure-reducing valve 27 with fail-safe function is normal, the hydraulic fluctuation due to high control accuracy is achieved. It is possible to obtain a constant fail-safe pressure with suppressed.

(2) A device for continuing normal motor control for ON / OFF control in response to the pressure switch 28 when it is determined that the motor control system is normal despite the system failure determination Therefore, even when the system fails, when the motor control system of the electric motor 24 that drives the oil pump 25 is normal, it is possible to prevent the fail-safe pressure from decreasing due to the leakage of oil from the spool 35.

(3) Although the system has failed due to a failure such as a sensor abnormality, when the valve control system and the motor control system are normal, the dither-equipped control current i _1C is applied to the control solenoid coil 43 to provide the fail-safe pressure. The proportional electromagnetic pressure reducing valve 27 with the fail-safe function is provided because it is a device that retains and continues normal motor control that controls ON / OFF in response to the pressure switch 28.
The fail-safe frequency using the fail-safe spring 48 is reduced, and the practicality is improved.

(4) Since the proportional electromagnetic pressure-reducing valve 27 with fail-safe function having the fail-safe spring 48 is used as the proportional electromagnetic pressure-reducing valve, even if the valve control system and the motor control system are in failure, the spring force causes fail-safe operation. The pressure can be obtained.

Although the embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

For example, in the embodiment, the example of application to the front and rear wheel drive torque distribution control system is shown, but other control such as a hydraulic active suspension control system which requires a certain pressure hold at the time of system failure. It can also be applied to the system.

In the embodiment, the example using the proportional electromagnetic pressure reducing valve with the fail-safe function is shown, but the invention can be applied to the vehicle hydraulic control unit using the proportional electromagnetic pressure reducing valve as described in the prior art. .

[0067]

According to the first aspect of the present invention, in a hydraulic control unit for a vehicle having an oil pump motor that is drive-controlled and a proportional electromagnetic pressure reducing valve, the valve is not determined even when a system failure is determined. When the operation control system fail judgment means judges that the valve operation control system is normal, a constant pressure holding control means for outputting a control command for holding a constant control pressure to the drive current applying means is provided, and the proportional electromagnetic pressure reducing means is provided. Since a constant control pressure is obtained by applying a dithered current to the solenoid of the valve, even if the system fails, the hydraulic pressure fluctuation with high control accuracy can be achieved when the valve operation control system of the proportional solenoid pressure reducing valve is normal. It is possible to obtain a constant fail-safe pressure that suppresses

According to the second aspect of the present invention, in the vehicle hydraulic control unit according to the first aspect, the motor control system fails in the normal state by the motor control system fail determination means even when the system failure is determined. In addition to the above effects, the motor control of the oil pump motor is performed even when the system fails, because the motor control continuation means that outputs a command to continue the motor drive control to the motor drive control means is provided when it is determined that When the system is normal, it is possible to obtain an effect that it is possible to prevent reduction of the fail-safe pressure.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle hydraulic control unit of the present invention.

FIG. 2 is a front / rear wheel drive torque distribution control system diagram of a rear wheel drive base to which the vehicle hydraulic control unit according to the embodiment of the present invention is applied.

FIG. 3 is a diagram showing a hydraulic unit of the embodiment.

FIG. 4 is a cross-sectional view showing a proportional electromagnetic pressure reducing valve with a fail-safe function used in the hydraulic unit of the embodiment.

FIG. 5 is a block diagram of a fail-safe control system of the vehicle hydraulic control unit according to the embodiment.

FIG. 6 is a flowchart showing a flow of a fail-safe processing operation performed by the ETS control unit.

FIG. 7 is a cross-sectional view showing a proportional electromagnetic pressure reducing valve used in a conventional vehicle hydraulic control unit.

FIG. 8 is a fail-safe pressure characteristic diagram of a conventional proportional electromagnetic pressure reducing valve at a low oil temperature.

FIG. 9 is a failsafe pressure characteristic diagram due to oil leakage from a spool in a conventional proportional electromagnetic pressure reducing valve.

[Explanation of symbols]

 a Electric motor b Oil pump c Spool d Solenoid e Proportional electromagnetic pressure reducing valve f Drive current applying means g System fail judging means h Valve operation control system fail judging means i Constant pressure holding control means j Motor drive controlling means k Motor control system fail judgment Means m Motor control continuation means

Claims (2)

[Claims] 1. A proportional electromagnetic pressure reducing valve that has an oil pump driven by an electric motor, a spool, and a solenoid, and uses an input pressure from the oil pump as a control pressure according to a solenoid current value; Drive current applying means for applying a dithered current, system fail judging means for judging a failure of a control control system to which this hydraulic control unit is applied, and a valve operation control system for judging whether or not current control of the solenoid is possible When the valve operation control system fail judgment means judges that the valve operation control system is normal, even though it is the time of fail judgment by the fail judgment means and the system failure judgment means. A constant pressure holding control means for outputting a control command for holding a constant control pressure. A hydraulic control unit for a vehicle characterized by: 2. The vehicle hydraulic control unit according to claim 1, wherein a motor drive control means for controlling a motor drive current by monitoring a pump discharge pressure of the electric motor, and whether or not the motor control of the electric motor is possible. The motor control system fail judging means for judging and the motor drive when the motor control system fail judging means judges that the motor control system is normal despite the failure judgment by the system fail judging means. A hydraulic control unit for a vehicle, comprising: a motor control continuation unit that outputs a command to the control unit to continue motor drive control.