JP2008291962A - Fault diagnosis device for proportional valve - Google Patents

Abstract

An object of the present invention is to detect a sticking failure of a proportional valve with an inexpensive system.
A proportional valve drive instruction device for outputting a proportional valve instruction current for driving a proportional valve, a pressure measuring means for measuring a pressure of a pump, a proportional valve instruction current and a pump pressure. A proportional valve sticking determination device 13 for determining sticking of the proportional valve 6 based on the first pressure storage means for storing the pressure when the pump 1 is stopped, and after the pump 1 is stopped. And a first pressure difference calculating means for calculating a difference between pressures stored in the first and second pressure storing means, and the pump 1 is set for a predetermined time. When the pressure difference calculated by the first pressure difference calculation means is greater than or equal to a predetermined value when the pump 1 is stopped and the proportional valve 6 is instructed to “close” after the pressure is increased by operating, It is determined that there is an open sticking failure of the proportional valve 6.
[Selection] Figure 2

Description

  The present invention relates to a proportional valve failure diagnosis device, and more particularly to a proportional valve failure diagnosis device for inspecting a failure of a proportional valve of a vehicle hydraulic device.

  As a conventional failure diagnosis device, for example, a failure diagnosis device for a solenoid valve having a plunger, which detects a supply current to the solenoid valve, pays attention to a change in current, and is normal when a negative change is detected. A diagnostic device for determination has been proposed (see, for example, Patent Document 1).

  Also, a failure diagnosis mode is defined that outputs a control signal for causing the solenoid valve to perform a specific failure diagnosis operation when the pump discharge flow rate is constant, and actual failure diagnosis is performed in the failure diagnosis mode. There is a diagnostic device that outputs a control signal to cause a failure diagnosis of a solenoid valve (see, for example, Patent Document 2).

JP-A-8-291877 JP 2000-46015 A

  However, in the conventional device disclosed in Patent Document 1, it is necessary to shorten the sampling time (several ms or less) in order to detect a change in the supply current to the solenoid valve. If it is attempted to shorten the sampling time here, it is technically possible, but a high-spec (high performance) microcomputer is required to realize it, and an expensive system is required. There was a problem that the cost would be high.

  Moreover, in the conventional method shown by patent document 2, it is necessary to continue operating a pump, when performing failure diagnosis. Therefore, for example, in the case of a system that requires pump drive by an electric motor, there has been a problem that wasteful battery power is consumed for fault diagnosis.

  The present invention has been made to solve such problems, and an object of the present invention is to obtain a proportional valve failure diagnosis device that detects a fixed valve fixing failure with an inexpensive system.

  The present invention relates to a failure diagnosis device for a proportional valve of a vehicle hydraulic system having a pump, an accumulator, and a proportional valve, and a proportional valve drive instruction means for outputting a proportional valve instruction current for driving the proportional valve; A pressure measuring means for measuring the pump pressure of the pump; and a proportional valve sticking determining means for making a sticking judgment of the proportional valve based on the proportional valve command current and the pump pressure. The means includes a first pressure storage means for storing the pump pressure when the pump is stopped, a second pressure storage means for storing the pump pressure after a predetermined time has elapsed since the stop of the pump, and the first pressure storage means. And a first pressure difference calculating means for calculating a difference between the pump pressures respectively stored in the second pressure storage means, and after the pump is operated for a predetermined time to increase the pressure, When the proportional valve is “closed” and the difference in the pump pressure calculated by the first pressure difference calculation means is greater than or equal to a predetermined value, an open sticking failure of the proportional valve It is a failure diagnosis device for a proportional valve that is determined to be present.

  The present invention relates to a failure diagnosis device for a proportional valve of a vehicle hydraulic system having a pump, an accumulator, and a proportional valve, and a proportional valve drive instruction means for outputting a proportional valve instruction current for driving the proportional valve; A pressure measuring means for measuring the pump pressure of the pump; and a proportional valve sticking determining means for making a sticking judgment of the proportional valve based on the proportional valve command current and the pump pressure. The means includes a first pressure storage means for storing the pump pressure when the pump is stopped, a second pressure storage means for storing the pump pressure after a predetermined time has elapsed since the stop of the pump, and the first pressure storage means. And a first pressure difference calculating means for calculating a difference between the pump pressures respectively stored in the second pressure storage means, and after the pump is operated for a predetermined time to increase the pressure, When the proportional valve is “closed” and the difference in the pump pressure calculated by the first pressure difference calculation means is greater than or equal to a predetermined value, an open sticking failure of the proportional valve Since it is a proportional valve failure diagnosis device that determines that there is, it is possible to detect a proportional valve sticking failure with an inexpensive system.

Embodiment 1 FIG.
Hereinafter, a failure diagnosis apparatus according to Embodiment 1 of the present invention will be described. In the first embodiment, a case where the failure diagnosis apparatus of the present invention is used for controlling a four-wheel drive vehicle will be described as an example.

  FIG. 1 is a diagram showing a four-wheel drive vehicle to which a failure diagnosis apparatus according to the present embodiment is applied. In FIG. 1, 41 is a front left wheel, 42 is a front right wheel, 43 is a rear left wheel, 44 is a rear right wheel, 45 is a transmission, 46 is an engine, 47 is a center differential, 48 is a clutch, 49 is a key SW on detection. Means, 51 is a hydraulic system, 52 is a front differential, 53 is a rear differential, and 60 is a clutch hydraulic pressure. Reference numeral 8 denotes a vehicle control device as a failure diagnosis device according to the present embodiment.

  The front left wheel 41 and the front right wheel 42 are connected via a front differential 52, and the rear left wheel 43 and the rear right wheel 44 are connected via a rear differential 53. The front differential 52 and the rear differential 53 are connected via a center differential 47, and a transmission 45 is connected to the center differential 47.

  Next, the operation of the four-wheel drive vehicle of FIG. 1 will be described. Torque generated by the engine 46 is transmitted to the transmission 45, and the transmission 45 decelerates or increases the speed. The output of the transmission 45 is transmitted to the center differential 47, and the center differential 47 transmits driving force to the front differential 52 and the rear differential 53.

  When the vehicle turns, the turning radii taken by the four wheels 41 to 44 are different, so that the rotational speeds of the four wheels 41 to 44 are different. Here, if the four wheels 41 to 44 are directly connected, the difference in the number of revolutions during the turning described above acts as a force that prevents the turning. This phenomenon is called a tight corner brake phenomenon.

  In order to prevent the tight corner braking phenomenon, a differential gear is mounted on the vehicle. That is, the front differential 52 is mounted to absorb the rotational speed difference between the front left wheel 41 and the front right wheel 42, and the rear differential 53 is mounted to absorb the rotational speed difference between the rear left wheel 43 and the rear right wheel 44. It is installed. Further, in the case of a four-wheel drive vehicle as shown in FIG. 1, a center differential 47 is mounted to absorb the difference in rotational speed between the front wheels 41 and 42 and the rear wheels 43 and 44.

  Here, the function of the differential gear will be described using the front differential 52 as an example. The front differential 52 transmits the rotation transmitted from the center differential 47 to the front left wheel 41 and the front right wheel 42. Since the load applied to the front left wheel 41 and the front right wheel 42 is the same when the vehicle is traveling straight, the front differential 52 transmits the rotation transmitted from the center differential 47 to the front left wheel 41 and the front right wheel 42. Distribute evenly. On the other hand, when the vehicle is turning left, the turning radius of the front left wheel 41 is smaller than the turning radius of the front right wheel 42, so the load on the front left wheel 41 is greater than the load on the front right wheel 42. . In this case, the front differential 52 transmits more rotation transmitted from the center differential 47 to the front right wheel 42 than to the front left wheel 41. As described above, the differential gear has a property of distributing the rotation to be transmitted so that the rotation distributed to the side with the lower load is larger than the rotation distributed to the side with the higher load.

  Next, a case where the four-wheel drive vehicle is accelerated will be described. When a four-wheel drive vehicle accelerates, a large vehicle body load is applied to the rear wheel side, and the load on the rear wheel increases. Here, since the center differential 47 has a function of transmitting a large amount of rotation to a direction with less load, the rotation transmitted from the transmission 45 is transmitted more to the front wheels 41 and 42 than to the rear wheels 43 and 44. , 42 is heavily loaded, and the driving force is hardly transmitted to the heavily loaded rear wheels 43, 44 side. Accordingly, the acceleration performance decreases.

  Therefore, in order to prevent deterioration in acceleration performance due to the provision of the center differential 47, a device for limiting the differential of the center differential 47 is provided. In the first embodiment, a clutch 48 is added to the center differential 47 as a differential limiting device.

  By controlling the binding force of the clutch 48 added to the center differential 47, the two output shafts of the center differential 47 can be controlled from a differential-free state to a state close to direct connection, and the differential of the center differential 47 can be limited. And it becomes possible to prevent the fall of the acceleration performance by providing the center differential 47. FIG.

  Next, a method for controlling the binding force of the clutch 48 will be described. The restraint force of the clutch 48 is controlled using hydraulic pressure. For example, when it is desired to increase the restraining force, the hydraulic pressure 51 to the clutch 48 is increased by the hydraulic system 51. Conversely, when it is desired to reduce the binding force, the hydraulic pressure 51 to the clutch 48 is reduced by the hydraulic system 51.

  FIG. 2 is a block diagram showing an internal configuration of the control device 8 and the hydraulic system 51 according to the first embodiment. As shown in FIG. 2, the control device 8 is provided with a pump drive logic 11, a proportional valve drive instruction device 12, a proportional valve sticking determination device 13, and a pressure measuring means 14. The hydraulic system 51 includes a pump 1, a check valve 2, a relief valve 3, a pressure sensor 4, an accumulator 5, a proportional valve 6, a clutch 7, and a motor 10. In FIG. 2, 9 is a proportional valve command current input from the control device 8 to the hydraulic system 51.

  The control device 8 outputs an operation instruction to the motor 10 by the pump drive logic 11 when it is desired to operate the pump 1 of the hydraulic system 51. When the motor 10 receiving the operation instruction is immediately activated, the pump 1 connected to the motor 10 by the shaft is activated.

  When the pump 1 is operated, the hydraulic oil in the tank is sent to the accumulator 5 via the check valve 2 provided to prevent the backflow of the hydraulic oil.

  The pressure sensor 4 measures the pressure of hydraulic oil accumulated in the accumulator 5 (hereinafter referred to as pump pressure), and transmits an electric signal such as a voltage value corresponding to the pump pressure to the pressure measuring means 14 of the control device 8.

  The pressure measuring means 14 of the control device 8 processes the signal from the pressure sensor 4, calculates the pump pressure based on the signal, and sends information to the pump drive logic 11. The pump drive logic 11 issues a stop instruction of the motor 10 when the pump pressure becomes larger than a preset pump stop pressure set value, and the pump operation pressure set value (not shown) is set. It is programmed to issue an operation instruction for the motor 10 when it becomes smaller.

  The proportional valve 6 receives the proportional valve command current 9 calculated by the proportional valve drive command device 12 of the control device 8, and according to this, the opening degree of a valve (not shown) in the proportional valve 6 is set. It can be adjusted. By adjusting the opening of the valve, the hydraulic oil accumulated in the accumulator 5 can be flow-controlled and sent to the clutch 7.

  For example, the control device 8 increases the proportional valve instruction current 9 calculated by the proportional valve drive instruction device 12 to increase the valve opening of the proportional valve 6. And by increasing the valve opening degree of the proportional valve 6, it is possible to operate the clutch 7 by flowing a large amount of hydraulic oil to the clutch 7.

  The relief valve 3 is a device that bypasses the accumulator 5 and the tank when a predetermined pressure (for example, several MPa) or more is reached.

  For example, when the pressure sensor 4 is broken and the pressure cannot be measured, it is assumed that the pump stop instruction cannot be issued and the pump 1 continues to operate. At this time, it is conceivable that the pump pressure increases and the hydraulic piping is ruptured. In such a case, the relief valve 3 bypasses the accumulator 5 and the tank at a predetermined pressure, and thus has a function of protecting the system from such a dangerous state.

  The proportional valve sticking determination device 13 of the control device 8 includes the pump pressure measured by the pressure measuring means 14, the proportional valve command current 9 output from the proportional valve drive command device 12, the information of the pump drive logic 11, and Based on the key SW signal input to the control device 8 from the key SW on detection means 49, the sticking determination of the proportional valve 6 is performed.

  As shown in FIG. 8, the proportional valve sticking determination device 13 stores the first pressure storage means 13a for storing the pump pressure when the pump is stopped, and the pump pressure after a predetermined time has elapsed since the pump was stopped. Second pressure storage means 13b and first pressure difference calculation means 13c for calculating the difference between the pump pressures respectively stored in the first pressure storage means and the second pressure storage means are provided.

  The proportional valve sticking determination device 13 calculates the difference in pressure stored in the first pressure storage means 13a and the second pressure storage means 13b by the first pressure difference calculation means 13c, and the calculated pressure difference is preset. When the value is equal to or greater than the predetermined value, it is determined that the proportional valve 6 is stuck open.

  If the proportional valve 6 is not open and fixed here, it is conceivable that the pump pressure does not decrease even after the pump is stopped, and the pressure value is maintained. On the other hand, if the pump pressure after a predetermined time (for example, several seconds) has elapsed from the pump pressure immediately after the pump stops, the proportional valve 6 is in an open state, even though the proportional valve 6 is instructed to be “closed”. Can be considered.

  Further, as shown in FIG. 8, the proportional valve adhering determination device 13 instructed to open the proportional valve 6 and the third pressure storage means 13d for storing the pump pressure immediately before instructing to “open” the proportional valve 6. The fourth pressure storage means 13e for storing the pump pressure after the elapse of a predetermined time set in advance, and the second for calculating the difference between the pump pressures respectively stored in the third pressure storage means 13d and the fourth pressure storage means 13e. Pressure difference calculation means 13f is provided.

  The proportional valve sticking determination means 13 calculates the pressure difference stored in the third pressure storage means 13d and the fourth pressure storage means 13e by the second pressure difference calculation means 13f, and the calculated pressure difference is less than a predetermined value. In the case, it is determined that it is closed and fixed.

  If the proportional valve 6 is not closed and fixed here, it is conceivable that the pump pressure drops due to the execution of the “open” instruction of the proportional valve 6. On the other hand, when the proportional valve 6 is fixedly closed, if the pump pressure does not change despite the “open” instruction of the proportional valve 6, the proportional valve 6 may be closed. It is done.

  In the present embodiment, the key SW on detection means 49 for detecting the on / off state of the key SW having the engine start on contact and the start contact and outputting the key SW signal indicating the detection result is provided. A fault diagnosis is performed immediately after the key SW is detected.

  This is intended to perform failure detection immediately after detection of the key SW on, thereby surely performing failure diagnosis with a low influence on the vehicle of the hydraulic control device before the vehicle departs.

  Next, the failure diagnosis method will be described in detail with reference to the time charts of FIGS.

  FIG. 3 is a time chart showing a response in a normal state where the proportional valve 6 is not stuck and failed.

  In FIG. 3, the pump pressure starts to increase by operating the pump 1 at time t1.

  Next, since the pump pressure has reached the pump stop pressure set value at time t2, the pump operation instruction is “stop”.

  Here, the stop pressure (proportional valve command current 9 is set to 0 A) from the proportional valve drive instructing device 12 during the period of time t2 to t3, the pump pressure maintains the pump stop pressure setting value.

  Next, since the proportional valve drive instructing device 12 is instructed to drive from time t3 to time t4 (the proportional valve command current 9 is not 0A), the pump pressure starts to be reduced when the proportional valve 6 is opened.

  After time t4, the stop pressure (proportional valve command current 9 is set to 0A) is again set from the proportional valve drive instructing device 12, so that the pump pressure maintains the pressure at time t4.

  FIG. 4 is a time chart showing the response when the proportional valve 6 is fixed open.

  In FIG. 4, the pump pressure starts to increase by operating the pump 1 at time t1.

  Next, since the pump pressure reaches the pump stop pressure setting value at time t2, the pump operation instruction is “stop”.

  At this time, since the proportional valve 6 is fixed open, the pump is stopped at the same time as the pump is stopped at time t2.

  In this way, if the proportional valve 6 is normal, the pump pressure should be maintained at a constant value when the proportional valve drive instruction device 12 issues a stop instruction (the proportional valve instruction current 9 is 0 A). However, after the pump 1 is stopped, it is possible to detect that the pressure has decreased by a predetermined value and to detect that the proportional valve is open.

  FIG. 5 is a time chart showing a response when the proportional valve 6 is closed and fixed.

  In FIG. 5, the pump pressure starts to rise by operating the pump 1 at time t1.

  Next, since the pump pressure reaches the pump stop pressure setting value at time t2, the pump operation instruction is “stop”.

  Here, during the period from time t2 to t3, the proportional valve drive instruction device 12 gives a stop instruction (proportional valve instruction current 9 is 0A). At this time, the proportional valve 6 is not fixed open, so the pump pressure is set to the pump stop pressure setting. The value is maintained.

  Next, during the period from time t3 to t4, the proportional valve drive instruction device 12 is instructed to drive (the proportional valve instruction current 9 is not 0A). If the proportional valve 6 is normal, the pump pressure should start to drop by opening the valve. However, since it is closed and fixed, the pump pressure does not decrease and the pressure setting value for stopping the pump is maintained.

  As described above, if the proportional valve 6 is normal, the pump pressure should be reduced by opening the valve when the proportional valve drive instructing device 12 instructs to drive (the proportional valve command current 9 is not 0 A). However, it is possible to detect that the proportional valve is closed by noting that the pump pressure does not decrease when a drive command is issued from the proportional valve drive command device 12 (the proportional valve command current 9 is not 0 A).

  6 and 7 are flowcharts showing the flow of processing of the control device 8 according to the first embodiment. First, as shown in FIG. 6, it is determined in step S1 whether or not the key SW is in an ON state. If the key SW is off, proceed to No and end the program. On the other hand, if the key SW is on, the process proceeds to Yes, and the pump pressure is determined in step S2.

  In step S2, the pump pressure is determined. If the pump pressure is equal to or lower than the predetermined value, the process proceeds to No, and the pump drive process is performed in step S4. If the pump pressure is greater than or equal to the predetermined value, the process proceeds to Yes, a pump stop instruction is executed in step S3, and the pump pressure immediately after the pump stop is stored in the first pressure storage means 13a in step S5. Go to step.

  In step S6, the process waits until a predetermined time (about 1 second) elapses after the pump stop instruction in step S3. After waiting for a predetermined time, the process proceeds to step S7, and the pump pressure is stored in the second pressure storage means 13b. Next, in step 8, the difference between the pump pressure stored in step S5 and the pump pressure stored in step S7 is calculated.

  In step S9, the pump pressure difference calculated in step S8 is determined. If the pump pressure difference is greater than or equal to a predetermined value, the process proceeds to Yes, and in step S10, the proportional valve opening sticking abnormality is determined.

  If the result of determination in step S9 is that the proportional valve pressure difference is less than the predetermined value, the process proceeds to No, and processing from step S11 shown in FIG. 7 is executed.

  As shown in FIG. 7, in step S11, the pump pressure is stored in the third pressure storage means 13d.

  Next, in step S12, an instruction to open the proportional valve 6 is executed, and the process proceeds to step S13.

  In step S13, it waits until predetermined time (about 1 second) passes since the proportional valve 6 was instructed to open. After waiting for a predetermined time, the process proceeds to step S14.

  In step S14, the pump pressure after waiting for the predetermined time in step S13 is stored in the fourth pressure storage means 13e.

  Next, in step S15, the difference between the pump pressure stored in step S11 and the pump pressure stored in step S14 is calculated.

  In step S16, the pump pressure difference calculated in step S15 is determined. If it is less than the predetermined value, the process proceeds to No and the program is terminated. On the other hand, if the pump pressure difference is less than or equal to the predetermined value, the process proceeds to Yes, and a proportional valve closing sticking abnormality is determined in step S17. By executing the above processing, the failure diagnosis of the open and closed proportional valves is performed.

  As described above, the present embodiment is a proportional valve failure diagnosis apparatus for a vehicle hydraulic system including a pump, an accumulator, and a proportional valve, and a proportional valve instruction current 9 for driving the proportional valve 6. Proportional valve drive instructing device 12, pressure measuring means 14 for measuring pump pressure, proportional valve sticking determining device for making sticking judgment of proportional valve 6 based on proportional valve commanding current 9 and measured pump pressure 13. The proportional valve sticking determination device 13 includes a first pressure storage unit 13a that stores a pressure when the pump is stopped, a second pressure storage unit 13b that stores a pressure after a predetermined time has elapsed after the pump is stopped, and a first pressure storage. And a first pressure difference calculation means 13c for calculating a difference in pressure stored between the first pressure storage means and the second pressure storage means, and after the pump has been operated for a predetermined time to increase the pressure, the pump is stopped and proportional When the valve 6 is instructed to be “closed” and the pressure difference calculated by the first pressure difference calculation means is greater than or equal to a predetermined value, it is determined that the proportional valve 6 is in an open stuck failure.

  As a result, when the proportional valve 6 is open and fixed, the proportional valve is turned off when the pump pressure measured by the pressure measuring means 14 decreases when the output of the pump drive logic 11 changes from the motor drive to the motor stop state. Can be determined to be open-fixed. When the proportional valve 6 does not stick and operates normally, the pump pressure changes according to the state of the drive instruction of the proportional valve 6 while the pump 1 is operated for a predetermined time and the pump pressure is accumulated in the accumulator 5. If the pump pressure drops while the drive command for the proportional valve 6 is not issued, it is determined as an open fixing failure, and if the pump pressure does not drop while the drive command for the proportional valve 6 is issued, it is determined as a closed lock failure. Is done.

  As described above, since it is possible to determine the open fixing failure of the proportional valve 6 based on the output value of the pressure measuring means 14 already used in the pump drive logic 11, it is possible to use a special high-performance microcomputer without using a high-performance microcomputer. Adhesion can be reliably determined with an inexpensive system without adding a sensor. Further, useless battery power is not consumed for fault diagnosis.

  The proportional valve sticking determination device 13 further includes a third pressure storage means 13d for storing the pressure immediately before instructing to “open” the proportional valve, and the pressure after a predetermined time has elapsed after instructing to “open” the proportional valve 6. A fourth pressure storage means 13e for storing, and a second pressure difference calculation means 13f for calculating the difference between the pressures stored in the third pressure storage means 13d and the fourth pressure storage means 13e, respectively, and the pump 1 is predetermined After the pressure is increased by operating for a time, the pump 1 is stopped, and when the proportional valve 6 is instructed to "open", the proportional valve 6 is calculated when the pressure difference calculated by the second pressure difference calculating means 13f is not more than a predetermined value. Is determined to be a closed stuck-at fault. Thereby, when the proportional valve 6 is closed and fixed, it can be determined by the following logic. After the output of the pump drive logic 11 changes from the motor drive to the motor stop state, the proportional valve drive instruction device 12 issues a drive instruction (the proportional valve instruction current 9 is not 0 A), that is, an instruction to open the valve of the proportional valve 6. When the pump pressure measured by the pressure measuring means 14 does not change, it can be determined that the proportional valve is closed and fixed.

  Further, the failure diagnosis apparatus according to the present embodiment includes a key SW having an on contact and a start contact for starting the engine, and key SW on detection means 49 capable of detecting the on / off state of the key SW. Failure diagnosis is performed immediately after the key SW is turned on. Thus, by making the determination of the proportional valve sticking determination device 13 immediately after the key SW is turned on, it is possible to reliably perform a failure diagnosis with a low influence on the vehicle of the hydraulic control device before the vehicle departs. Become.

It is explanatory drawing which showed the four-wheel drive vehicle to which the failure diagnosis apparatus which concerns on Embodiment 1 of this invention is applied. It is the block diagram which showed the structure of the failure diagnosis apparatus which concerns on Embodiment 1 of this invention. 3 is a time chart showing when the proportional valve is normal in the failure diagnosis apparatus according to Embodiment 1 of the present invention. It is the time chart which showed the time of proportional valve open sticking in the failure diagnosis apparatus concerning Embodiment 1 of this invention. It is the time chart which showed the time of proportional valve closed adhering in the failure diagnosis apparatus concerning Embodiment 1 of this invention. It is the flowchart which showed the flow of the process of the failure diagnosis apparatus concerning Embodiment 1 of this invention. It is the flowchart which showed the flow of the process of the failure diagnosis apparatus concerning Embodiment 1 of this invention. It is the block diagram which showed the structure of the proportional valve sticking determination apparatus of the failure diagnosis apparatus concerning Embodiment 1 of this invention.

Explanation of symbols

  1 pump, 2 check valve, 3 relief valve, 4 pressure sensor, 5 accumulator, 6 proportional valve, 7 clutch, 8 control device, 9 proportional valve command current, 10 motor, 11 pump drive logic, 12 proportional valve drive command device, 13 proportional valve sticking determination device, 14 pressure measuring means.

Claims (3)

A failure diagnosis device for a proportional valve of a vehicle hydraulic system having a pump, an accumulator, and a proportional valve,
Proportional valve drive instruction means for outputting a proportional valve instruction current for driving the proportional valve;
Pressure measuring means for measuring the pump pressure of the pump;
Proportional valve sticking determination means for determining sticking of the proportional valve based on the proportional valve command current and the pump pressure,
The proportional valve sticking determining means includes
First pressure storage means for storing the pump pressure when the pump is stopped;
Second pressure storage means for storing a pump pressure after a predetermined time has elapsed since the pump was stopped;
A first pressure difference calculating means for calculating a difference between the pump pressures respectively stored in the first pressure storing means and the second pressure storing means;
The pump pressure difference calculated by the first pressure difference calculating means when the pump is stopped for a predetermined time and the pump is stopped and the proportional valve is instructed to be closed. A proportional valve failure diagnosis device, wherein when the value is equal to or greater than a predetermined value, it is determined that the proportional valve is in an open stuck failure. A failure diagnosis device for a proportional valve of a vehicle hydraulic system having a pump, an accumulator, and a proportional valve,
Proportional valve drive instruction means for outputting a proportional valve instruction current for driving the proportional valve;
Pressure measuring means for measuring the pump pressure of the pump;
Proportional valve sticking determination means for determining sticking of the proportional valve based on the proportional valve command current and the pump pressure,
The proportional valve sticking determining means includes
Third pressure storage means for storing the pump pressure immediately before instructing to "open" the proportional valve;
A fourth pressure storage means for storing a pump pressure after a predetermined time has elapsed after instructing to "open" the proportional valve;
A second pressure difference calculating means for calculating a difference between the pump pressures stored in the third pressure storing means and the fourth pressure storing means,
The pump pressure difference calculated by the second pressure difference calculation means when the pump is operated for a predetermined time to increase the pressure and then the pump is stopped and the proportional valve is instructed to “open”. The proportional valve failure diagnosis device according to claim 1, wherein the proportional valve is determined to be a closed stuck-at failure when the value is equal to or less than a predetermined value. A key SW having an on contact and a start contact for starting the engine;
A key SW on detection means for detecting the on / off state of the key SW;
3. The proportional valve failure diagnosis apparatus according to claim 1, wherein failure diagnosis is performed immediately after detection of key SW on.

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