JPH0797982A - Controller of variable displacement pump - Google Patents

Abstract

PURPOSE:To provide a controller of a variable displacement pump which can accurately detect the abnormal flow rate of discharge of the variable displacement pump without errors. CONSTITUTION:When a pressure switch 15 which is on with line pressure reaching abnormally high pressure and is off with the line pressure decreased and recovered to normal pressure provides an on-switch signal, an unloading valve 14 is operated to unload the delivery side of a variable displacement pump 1, while when the pressure switch 15 is off the unloading valve 14 is recovered to its on-load state; the time from the recovery until the pressure switch 15 is on again is measured to determine the speed at which the pressure builds up, and when the pressure buildup speed is equal to or greater than a set value, i.e., when the time measured is short, a process against abnormality is executed in which the unloading valve 14 is held in its unloading state while an alarm sounds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement pump control device capable of accurately determining an abnormal state of a variable displacement pump without erroneously detecting it.

[0002]

2. Description of the Related Art As a conventional controller for a variable displacement pump, for example, Japanese Patent Laid-Open No. 3-1996 previously proposed by the present applicant.
Some are described in Japanese Patent Publication No. 84. In this conventional example, a suction means is constituted by a valve means which responds to the discharge pressure of the variable displacement pump as a pilot pressure and determines the opening degree, and the suction throttle valve is inserted in the suction passage of the variable displacement pump. Thus, when the discharge pressure of the variable displacement pump becomes high, the discharge flow rate is reduced, and the discharge pressure of the variable displacement pump is set to the minimum amount required by the equipment operated by this to save pump drive energy. I am trying to do it.

When an active suspension is constructed by using this variable displacement pump, a hydraulic control system as schematically shown in FIG. 10 is constructed. That is, the variable displacement pump 1 is composed of a radial piston pump 2 and a suction throttle valve 4 inserted between the suction side pipe 3 and the tank 12, and the suction of the radial piston pump 2 is provided to the suction throttle valve 4. The discharge pressure of the side pipe 5 is fed back to the feedback pipe 4
By feeding back through a, even if the amount of working fluid consumed by the load fluctuates, the discharge amount of the radial piston pump 2 is increased or decreased according to the change of the working fluid amount to change the discharge pressure of the radial piston pump 2. I try to keep it constant.

Here, since the radial piston pump 2 utilizes the sucked hydraulic oil as its internal lubricant, a bypass flow passage 7 having a fixed throttle valve 7a bypassing the suction throttle valve 4 is formed. Therefore, the minimum flow rate of hydraulic oil is specified without restricting the suction amount (or discharge amount) to zero. Then, the discharge pressure of the variable displacement pump 1 is supplied via the discharge side pipe 5 and the check valve 8 to the pressure control valve 9 whose control pressure is controlled by the posture change suppression pressure command signal from the control device 19, and this pressure is supplied. The control pressure controlled by the control valve 9 is supplied to the hydraulic cylinder 10 that constitutes the active suspension.

The pressure control valve 9 has an input port 9a, a return port 9b and a control pressure port 9c.
Is connected to the check valve 8 and the return port 9b is connected to the return side pipe 1
1 is connected to the oil tank 12, and the control pressure port 9c is connected to the hydraulic cylinder 10. In such a hydraulic control system using the variable displacement pump, since the variable displacement pump does not perform unnecessary discharge, the temperature rise of the hydraulic oil is small and the oil cooler for cooling the hydraulic oil can be omitted. Have

However, if the suction throttle valve 4 is stuck in an open state for some reason, the discharge flow rate will remain high, and the flow rate control corresponding to the discharge pressure will not be possible. It will rise abnormally.
Therefore, in order to limit the supply pressure of the hydraulic control system to a constant value, a safety valve is usually provided between the discharge side pipe 5 of the variable displacement pump 1 and the return pipe 11 connected to the tank 12 as shown in FIG. The relief valve 13 is inserted. In this way, when the relief valve 13 is inserted, the variable displacement pump 1 can be operated when an abnormality occurs in the variable displacement pump 1.
The hydraulic oil discharged from the valve is relieved by the relief valve 13, the pressure energy is converted into heat and the hydraulic oil is heated, and the hydraulic oil temperature rises. Requires an oil cooler.

In order to avoid this rise in hydraulic oil temperature,
Generally, as shown in FIG. 10, the pressure switch 1 that is turned on when the discharge pressure of the variable displacement pump 1 becomes an abnormally high pressure set lower than the set pressure of the relief valve 13.
5, the switch signal of the pressure switch 14 is input to the control device 19, and the control device 19 determines whether the variable displacement pump 1 is abnormal.
Thus, the unload valve 14 inserted in parallel with the relief valve 13 is controlled to an unload state to reduce the pump load and prevent the temperature rise of the hydraulic oil due to the relief heat generation.

[0008]

However, in the above-mentioned conventional variable displacement pump control device, since the variable displacement pump 1 utilizes the hydraulic oil sucked by itself for internal lubrication as described above, the suction amount is increased. That is, the minimum flow rate Qp of the discharge amount is defined, and even if the pressure control valve 9 has an internal leak and the fluid cylinder 10 is in a no-load state, the internal leak causes a gap between the input port 9a and the return port 9b. A certain amount of minute flow rate Qv of hydraulic oil flows, therefore
In the discharge side pipe 5, the working oil always flows in a flow rate of at least the minimum flow rate.

Here, the minimum flow rate Qp of the variable displacement pump 1
Is less than the leak flow rate Qv of the pressure control valve 9 (Qp <Q
In the case of v), even if the fluid cylinder 10 is in an unloaded state and the variable displacement pump 1 reaches the minimum discharge amount Qp, the leak flow rate Qv of the pressure control valve 9 is larger, so that the discharge side pipe 5 The internal pressure never rises. Since the pressure switch 15 is turned on only when the variable displacement pump 1 is in an abnormal state, the switch signal of the pressure switch 15 can accurately determine the abnormality of the variable displacement pump 1. There is no.

However, contrary to the above, the variable displacement pump 1
When the minimum flow rate Qp of the pressure control valve 9 is larger than the leak flow rate Qv of the pressure control valve 9 (Qp> Qv), there is no road surface input and no vehicle height control is performed as when the vehicle is stopped, and the pressure of the fluid cylinder 10 Under the condition that it is not necessary to control the minimum flow rate Qp of the variable displacement pump 1 and the leak flow rate Q of the pressure control valve 9,
Variable capacity pump 1 due to unbalance of flow balance with v
However, there is an unsolved problem that the control device 19 causes the unload valve 14 to malfunction by erroneously detecting that the discharge pressure is increasing and the pressure switch 15 erroneously detects that the pump is abnormally high.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, and of course, it is possible to detect the failure judgment of the variable displacement pump due to the increase of the discharge amount, and it is possible to detect it. An object of the present invention is to provide a control device for a variable displacement pump that does not erroneously detect a pump abnormality in the normal operation in which the minimum flow rate of the displacement pump is larger than the leak flow rate of the pressure control valve and is a large flow rate. .

[0012]

In order to achieve the above-mentioned object, a control device for a variable displacement pump according to claim 1 has a structure as shown in FIG.
As shown in the basic configuration diagram of (a), a variable displacement pump that supplies a working fluid to one end of a supply side pipe with at least a minimum flow rate regulated, and is connected to the other end of the supply side pipe via a control valve. Fluid working equipment, line pressure abnormality detecting means for detecting that the line pressure of the supply side pipe is in an abnormal state, and suppressing the line pressure when the line pressure abnormality detecting means detects the line pressure abnormal state. In a variable displacement pump control device including line pressure control means, the line pressure control means detects the unload valve disposed on the discharge side of the variable capacity pump and the line pressure abnormality detection by the unload valve. Means for unloading when the line pressure abnormal state is detected by the means, and for releasing the unload state when the line pressure returns to a normal value, and unloading by the valve control means When the unloading state is released, the rising speed measuring means for measuring the line pressure rising speed based on the line pressure detection value of the line pressure detecting means, and the line pressure rising speed of the rising speed measuring means is not less than a set value. And a pump abnormality control unit that determines that the variable displacement pump is in an abnormal state and controls the unload valve to an unload state.

In the control device for the variable displacement pump according to the second aspect, as shown in the basic configuration diagram of FIG. 1B, at least the minimum flow rate is regulated to supply the working fluid to one end of the supply side pipe. A variable displacement pump, a fluid actuated device connected to the other end of the supply side pipe via a control valve, line pressure abnormality detection means for detecting that the line pressure of the supply side pipe is in an abnormal state, In a control device for a variable displacement pump, comprising: a line pressure control device that suppresses the line pressure when the line pressure abnormality detection device detects an abnormal line pressure condition, wherein the line pressure control device is a discharge side of the variable displacement pump. A relief valve and an unload valve arranged in parallel with each other, a temperature detecting means for detecting the temperature of the working fluid discharged from the variable displacement pump, and a line pressure abnormal state by the line pressure abnormality detecting means. Pump abnormality control means for controlling the unload valve to an unloading state by detecting that the variable displacement pump is in an abnormal state when the detected temperature value of the temperature detecting means is equal to or more than a set value. It is characterized by

[0014]

In the variable displacement pump control device according to the first aspect of the present invention, when the minimum flow rate of the variable displacement pump is larger than the leak flow rate of the control valve, for example, when the vehicle is at a stop and is consumed by passing through the control valve. When there is almost no flow rate, the line pressure in the supply side pipe increases according to the difference between the minimum flow rate of the variable displacement pump and the leak flow rate of the control valve, and if the line pressure exceeds the set value, the line pressure abnormality detection means Detected as an abnormal line pressure condition. In this state, the valve control means sets the unload valve to the unload state, so that the discharge side of the variable displacement pump is put into an unloaded state, and the line pressure decreases due to the leak flow rate of the control valve, and the normal state is restored. The unload valve is returned to the on-load state by the valve control means, and the rising speed of the line pressure thereafter is measured by the rising speed measuring means. When the line pressure increase speed is less than the set value by the pump abnormality detecting means, it is simply judged that the increase is a natural increase due to the difference between the minimum flow rate of the variable displacement pump and the leak flow rate of the control valve, and the unload state of the unload valve is determined. And the on-load state is repeated, and when the line pressure increase rate is equal to or higher than the set value, it is determined that the discharge flow rate of the variable displacement pump is abnormal, and the unload valve is held in the unload state.

Further, in the variable displacement pump control device according to the second aspect, since the leak flow rate of the control valve has temperature dependency, the control valve is controlled when the minimum flow rate of the variable displacement pump is relatively high in fluid temperature. This is effective when the leak flow rate of the pressure control valve is lower than the minimum flow rate of the variable displacement pump when the fluid temperature is low, but the viscosity of the working fluid becomes high when the fluid temperature is low. When the leak flow rate from the control valve decreases below the minimum flow rate of the variable displacement pump, the line pressure of the supply side pipe increases when the flow rate consumed by the control valve is only the leak flow rate, such as when the vehicle is stopped. Then, when the line pressure reaches the relief pressure of the relief valve connected to the discharge side of the variable displacement pump, it is drained through this relief valve, and the heat generation at this time raises the working fluid temperature,
As a result, the leak flow rate of the control valve increases and the line pressure is maintained at a normal value without passing through the relief valve. However, if a discharge pressure abnormality of the variable displacement pump occurs, the discharge flow rate of the variable displacement pump becomes much higher than the leak flow rate of the control valve, and the flow rate of the working fluid passing through the relief valve also increases. Since the abnormal temperature of the line increases and the abnormal state of the line pressure continues, the pump abnormality control unit determines that the discharge flow rate of the variable displacement pump is abnormal and holds the unload valve in the unload state.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a hydraulic system diagram showing the first embodiment of the present invention. As in the case of FIG. 10 described above, the discharge pressure of the radial pump 2 installed in the radial pump 2 and its suction side pipe 3 is feedback pipe 4a. A variable displacement pump 1 provided with a suction passage throttle valve 4 fed back via a suction passage, and a bypass passage 7 having a fixed throttle 7a connected in parallel with the suction passage throttle valve 4 and a discharge side thereof. Discharge side piping 5
And the input port 9 through the check valve 8 to the discharge side pipe 5.
a, a pressure control valve 9 connected to the pressure control valve 9, a hydraulic cylinder 10 connected to a control pressure port 9c of the pressure control valve 9 and interposed between a wheel and a vehicle body, and hydraulic oil from a return port 9b of the pressure control valve 9. Oil tank 12 which receives the hydraulic oil through the return side pipe 11 and supplies the hydraulic oil to the variable displacement pump 1.
And a relief valve 13 and an unload valve 14 which are interposed in parallel between the discharge side pipe 5 and the return side pipe 11 between the variable displacement pump 1 and the check valve 8, the check valve 8 and the pressure. Accumulator 17 connected to the discharge side pipe 5 between the control valves 9
And a pressure switch 15 that is turned on when the line pressure of the discharge side pipe 5 between the check valve 8 and the pressure control valve 9 is lower than a preset pressure of the relief valve 13, and a switch of this pressure switch 15. A control device 19 that receives a signal and controls the pressure control valve 9 and the unload valve 14 is provided.

Here, as shown in FIG. 3, in the pressure switch 15, the line pressure rises from the normal pressure so that the relief valve 13 is released.
When the abnormal high pressure set value P _A lower than the set pressure is over, the line is turned on, and the line pressure is lowered from the abnormal high pressure set value P _A or over to the normal pressure set value P _N lower than the abnormal high pressure set value P _A. When this occurs, it has a hysteresis characteristic of being turned off.

The control device 19 has, for example, a microcomputer 20 having an input interface circuit 20a, an output interface circuit 20b, an arithmetic processing device 20c and a storage device 20d such as a RAM and a ROM. Switch signal SS is input, and a detection signal DS from a posture change detection or estimation means 21 such as a lateral acceleration sensor, a longitudinal acceleration sensor, and a stroke sensor capable of detecting or predicting a posture change of the vehicle body is input, and an output interface. Circuit 20b
An alarm circuit 22, which is installed near the driver's seat and outputs an alarm and / or an alarm sound when an alarm signal is input,
A solenoid drive circuit 23 that drives the electromagnetic proportional solenoid 9a of the pressure control valve 9 according to the pressure command value and a solenoid drive circuit 24 that turns on and off the electromagnetic solenoid 14a of the unload valve 14 are connected.

Further, the arithmetic processing unit 20c calculates a pressure command value for suppressing posture changes such as roll, pitch and bounce of the vehicle body on the basis of the detection signal DS read via the input interface circuit 20a, and calculates it. Control signal C according to
S is output to the proportional electromagnetic solenoid 9 of the pressure control valve 9 via the output interface circuit 20b and the solenoid drive circuit 23.
The unload valve 14 is controlled via the output interface circuit 20b and the solenoid drive circuit 24 on the basis of the switch signal SS of the pressure switch 15 which is output to the output d and read via the input interface circuit 20a.
It is determined whether or not the line pressure increase rate of the discharge side pipe 5 is equal to or higher than a set value, and when the line pressure increase rate is equal to or higher than the set value, it is determined that the discharge flow rate abnormality of the variable displacement pump 1 has occurred, and the unload valve 14 is held in the unload state, and an abnormal state process of outputting the alarm signal AS to the alarm circuit 22 is executed.

Next, the operation of the above embodiment will be described with reference to the control device 19
A description will be given with reference to the flowchart of FIG. 4 showing an example of the processing procedure of FIG. The process of FIG. 4 is a predetermined time (for example, 10 msec)
It is executed as a timer interrupt process for each time, and first, step S1
Then, the switch signal SS of the pressure switch 15 is read, then the process proceeds to step S2, and the unload status flag FA indicating the state of the unload valve, that is, the unload state or the onload state is "1". If the flag FA is reset to "0" in the on-load state, the process proceeds to step S3 to determine whether the switch signal SS is in the on state, and the switch signal SS Is off, the discharge side pipe 5
When the line pressure is judged to be a normal pressure, the timer interrupt processing is terminated and the main program is returned to a predetermined state. When the switch signal SS is in the ON state, it is judged that the line pressure is in an abnormal state. Go to S4.

In this step S4, the unload valve 14
Control signal CA having a logical value of "1" is sent to the solenoid 14a of the unload valve 14 via the output interface circuit 20b, the unload flag is set to "1", and then the step S5
After that, the count value N for measuring the line pressure rise time, which will be described later, is cleared to "0", the timer interrupt process is terminated, and the process returns to the predetermined main program.

On the other hand, if the result of determination in step S2 is that the status flag FA is set to "1" because it is in the unload state, the process proceeds to step S6 and the increase rate of the line pressure is being measured. It is determined whether or not the status flag FB indicating that there is is set to "1", and when the status flag FB is reset to "0", the process proceeds to step S7 and the switch signal SS of the pressure switch 15 is sent. Is in the off state, and when it is in the on state, the timer interrupt processing is ended and the predetermined main program is returned to, and when it is in the off state, the process proceeds to step S8 and the Outputs a control signal CA having a logical value "0" for returning the load valve 14 to the on-load state.
Is sent to the solenoid 14a of the unload valve 14 via, and then the process proceeds to step S9 where the status flag F
After setting B to "1", the timer interrupt process is terminated and the process returns to the predetermined main program.

If the result of determination in step S6 is that the status flag FB is set to "1", the process proceeds to step S10 and it is determined whether or not the switch signal SS of the pressure switch 15 is in the ON state. If it is in the off state, the process proceeds to step S11 to increment the count value N for measuring the line pressure rise time by "1", and then proceeds to step S12 to set the count value N to a preset time-over time. It is determined whether or not the set value corresponding to the time is equal to or greater than No. If N <No, the timer interrupt process is terminated and the process returns to the predetermined main program. If N ≧ No, step S13 is performed. , The status flags FA and FB are both reset to "0", and then the process proceeds to step S14, where the count value N "0" to end the timer interrupt processing is cleared to return to the predetermined main program.

On the other hand, if the result of determination in step S10 is that the switch signal SS is in the on state, step S15
Then, it is determined whether or not the count value N is equal to or larger than the preset set value Ns. Here, the set value Ns is a normal pressure determined by the minimum flow rate Qp of the variable displacement pump 1 when the variable displacement pump 1 is in a normal state, the capacity of the accumulator 17 and the initial charged gas pressure, and the leak flow rate Qv of the pressure control valve 9. From the rise until the abnormal pressure is reached, the judgment time Ts obtained by adding a margin to the timer interrupt cycle t (=
It is set to a value divided by 10 msec).

When the determination result in step S15 is N ≧ Ns, it is determined that the line pressure naturally increases due to the difference between the minimum flow rate Qp of the variable displacement pump 1 and the leak flow rate of the pressure control valve 9, and the above step is executed. In step S16, the count value TA indicating the duration of the abnormal state is cleared to "0", and then in step S13 described above, both the status flags FA and FB are reset to "0", and then step S14. Then, the count value N is cleared to "0", the timer interrupt process is terminated, the predetermined main program is restored, and when N <Ns, there is a possibility that the discharge flow rate of the variable displacement pump 1 is abnormal. Judgment and Step S17
Move to.

In step S17, the count value TA representing the abnormal state duration is incremented by "1", and then the process proceeds to step S18, in which it is determined whether the count value TA has reached the set value TAs, and TA When <TAs, the process proceeds to step S19, the status flag FB is reset to "0", the timer interrupt process is terminated, and the predetermined main program is returned to TA ≧ T.
When it is As, it is determined that the discharge flow rate of the variable displacement pump 1 is abnormal, and the process proceeds to step S20.

In this step S20, the unload valve 1
4, the control signal CA of the logical value "1" for holding the unload state is output, the alarm signal AS is sent to the alarm circuit 22, and the posture change detection or estimation means 21 is also provided.
The abnormal processing for canceling the posture change suppression control based on the detection signal DS is executed, and then the processing is ended. In the processing of FIG. 4, the processing of steps S1 to S9 corresponds to the valve control means, the processing of steps S10 to S12 corresponds to the rising speed measurement means, and the processing of steps S15 to S20 corresponds to the abnormality control means. There is.

Therefore, when the vehicle is traveling, when the lane change is started from the straight traveling state, first, the steering wheel (not shown) is turned to the left to start the lane change. However, when the posture change detection or estimation means 21 detects the lateral acceleration generated in the vehicle body at this time, and the detection signal DS is input to the control device 19, the control device 1
In the arithmetic processing unit 20c in 9, the internal pressure is increased so as to generate thrust for resisting the sinking by the roll to the hydraulic cylinder 10 on the right side that is the outer wheel side of the turning, and the hydraulic cylinder 10 on the left side that is the inner wheel side of the turning is On the contrary, the control signal CS for reducing the internal pressure is formed so as to generate the thrust that suppresses the lifting due to the rolls, and the control signals CS are output to the proportional solenoids 9d of the pressure control valves 9 to suppress the roll of the vehicle body. You can

Next, after returning the steering wheel to the neutral position, when the steering wheel is turned back in the opposite direction, lateral acceleration in the opposite direction to the above occurs, so that the hydraulic cylinder 10 on the left side, which is the outer wheel side, turns. Hydraulic cylinder 1 on the right side, which is the inner ring side for turning, by increasing the internal pressure so as to generate thrust that resists the sinking by the roll.
On the contrary, control signals CS for decreasing the internal pressure so as to provide thrust for suppressing the lifting due to the roll are respectively formed at 0, and the control signals CS are output to the proportional solenoids 9d of the respective pressure control valves 9 to roll the vehicle body. Can be suppressed.

As described above, in order to suppress rolls, pitches, bounces, and the like that occur on the vehicle body while the vehicle is traveling,
The control pressure output from the control port of the pressure control valve 9 is controlled. In this case, when the control pressure is increased, the input port and the control pressure port are communication-controlled, and conversely the control pressure is decreased. In this case, since the control pressure port and the return port are controlled to communicate with each other, even when the vehicle is traveling straight on a relatively flat and good road, the pressure control valve 9 consumes a relatively large flow rate. The line pressure fluctuates, and the suction flow rate of the variable displacement pump 1 is controlled according to the fluctuation of the line pressure,
When the consumed flow rate is small, the engine load can be reduced, the line pressure is controlled to a value near the normal set pressure, and the switch signal SS of the pressure switch 15 continues to be in the off state. In this state, when the arithmetic processing unit 20c of the control unit 19 executes the process of FIG. 4, the timer interrupt process is directly terminated through steps S1 to S3, and therefore the abnormal process is not executed and the unloading is not performed. Valve 1
4 also maintains the closed state.

In this running state, if the spool of the variable displacement pump 1 is abnormally fixed on the side with a large suction amount due to, for example, foreign matter, the discharge flow rate of the variable displacement pump 1 becomes the line pressure, that is, the pressure control valve 9 side. Irrespective of the flow rate consumed, the line pressure rapidly increases as shown in FIG. 5 (b).
Then, at a time point t ₁ when the line pressure exceeds the abnormal high pressure set value of the pressure switch 15, the switch signal SS of the pressure switch 15 is turned on as shown in FIG. 5A, and in response thereto, the arithmetic processing unit 20c. When the process of FIG. 4 is executed in step S4, the process proceeds from step S1 to step S3 to step S4, and the control signal CA having the logical value “1” is transmitted to the unload valve 1
By being sent to the electromagnetic solenoid 14a of No. 4, the unload valve 14 is actuated and the discharge side of the variable displacement pump 1 is brought into the unload state. At this time, the input port of the pressure control valve 9 is cut off from the discharge side of the variable displacement pump 1 by the check valve 8, so that the line pressure is t at the time when the pressure control valve 9 consumes the accumulated pressure of the accumulator 17. Start decreasing from ₂ . In this state, when the process of FIG. 4 is executed, the process proceeds to step S7 through steps S1, S2 and S6, and since the pressure switch 15 continues to be in the on state, the unload state of the unload valve 14 is To continue.

After that, when the line pressure returns to the normal pressure set value as shown in FIG. 6 (b) at time t ₃ , the switch signal SS of the pressure switch 15 is turned off as shown in FIG. 5 (a). When the process of FIG. 4 is executed by returning, the process proceeds to step S8 via steps S1, S2, S6, S7, and the control signal CA having the logical value “0” is sent to the electromagnetic solenoid 14a of the unload valve 14. Then, the status flag FB is set to "1" in step S9. As a result, the unload valve 15 is returned to the on-load state, and the discharge pressure of the variable displacement pump 1 causes the line pressure to start rising again as shown in FIG. 5B.

At this time, the variable displacement pump 1 has an abnormality in which the discharge flow rate is fixed to a large amount, so that the rate of increase of the line pressure increases. Therefore, when the process of FIG. 4 is executed, the process proceeds to step S11 through steps S1, S2, S6 and S10, the count value N is repeatedly incremented, and the line pressure reaches the abnormal high pressure set value at time t _4. The switch signal SS of the pressure switch 15 is shown in FIG.
When it is turned on as shown in FIG.
From S to S15, it is determined whether or not the count value N at that time is equal to or more than the set value Ns. When N <Ns, the rising speed of the line pressure is too fast and the variable displacement pump 1 When it is determined that there is a high possibility that the discharge flow rate abnormality has occurred, the process proceeds to step S17, increments the count value TA indicating the abnormality continuation time, and then resets the status flag FB to "0" in step S19. After that, the timer interrupt processing ends.

Then, if the discharge flow rate abnormality of the variable displacement pump 1 continues, the count value TA is incremented by repeating the same processing as above, and when the count value TA reaches the set value TAs at the rotation t ₅ , step In step S20, the control signal CA having the logical value "1" is continuously output to the unload valve 15 to maintain the discharge side of the variable displacement pump 1 in the unload state.
An abnormal process is performed to stop the control of the pressure control valve 9.

However, when the vehicle is stopped and there is almost no change in vehicle height, the flow rate consumed by the pressure control valve 9 is only the leak flow rate, and this leak flow rate is less than the minimum discharge flow rate of the variable displacement pump 1. As shown in FIG. 6B, the line pressure starts to increase gradually at time t ₁₁ when the vehicle stops and the vehicle height does not change. At time t ₁₂ , the line pressure reaches the abnormal high pressure set value. When it reaches, the unload valve 14 is controlled to be in the unload state as in the case of the above-mentioned abnormal discharge flow rate, and then the line pressure is increased at time t ₁₃ when the accumulated pressure of the accumulator 17 is consumed by the leak flow rate of the pressure control valve 9. When the pressure gradually decreases and reaches the normal set pressure at time t ₁₄ , the switch signal SS of the pressure switch 15 is turned on, and the increment of the count value N is started.

At this time, the line pressure starts to rise,
Since the rising speed is the difference between the minimum discharge flow rate of the variable displacement pump 1 and the leak flow rate of the pressure control valve 9, the rising speed is slow, and at time t ₁₅ when the line pressure reaches the abnormal high pressure set value,
The count value N greatly exceeds the set value Ns,
When the processing of FIG. 4 is executed, N is returned in step S15.
Since ≧ N, this step S15 to step S1
6, the count value TA is cleared to "0", and the status flags FA and FB are reset to "0" and the count value N is cleared to "0". To do. Therefore, in the next process, the process proceeds from step S2 to step S3, and the pressure switch 15 is in the ON state. Therefore, the process proceeds to step S4 and the control signal CA having the logical value "1" is output, The load valve 14 is brought into an unloading state, then the status flag FA is set to "1", and then the above-mentioned determination processing is repeated.

As described above, when the variable displacement pump 1 is normal, the unload valve 15 does not simply repeat the unloading state and the onloading state, and the relief valve 13 does not enter the relief state. Can be reliably prevented from rising. Further, in a state where the variable displacement pump 1 is normal, the unload valve 14 returns from the unload state to the onload state, and steps S1, S2, S6 are performed.
When the vehicle starts traveling at time t ₁₆ in the state where the process from step S10 to step S12 is performed, the hydraulic oil is consumed by the pressure control valve 9, so that the line pressure is abnormally high. When the count value N does not rise to the set value and exceeds the set value No that is larger than the set value Ns, the process proceeds from step S12 to step S13 to reset both the status flags FA and FB to "0". The abnormality determination process is ended by clearing the count value N to "0".

On the other hand, while the vehicle is stopped, the variable displacement pump 1
When an abnormal discharge flow rate occurs, the unload valve 14
When the is returned from the unloading state to the on-loading state, as in the case of FIG. 5 (b) described above, the rising speed of the line pressure becomes faster, and the timing at which the pressure switch 15 is turned on becomes faster. When the value N becomes a value smaller than the set value Ns, the process proceeds from step S15 to step S17 to count up the count value TA for determining the abnormal continuation state, continue the abnormal state a predetermined number of times, and count value T
When A reaches the set value TAs, it is determined that the discharge flow rate of the variable displacement pump 1 is abnormal, and the process proceeds to step S20.
As in the case described above, the unload valve 14 is held in the unload state and the control of the pressure control valve 9 is stopped.

Note that the hydraulic oil may be consumed by the pressure control valve 9 during execution of the abnormality determination process, and the line pressure increase rate may become slow. In this case, the failure determination is not made even if the variable displacement pump 1 is out of order.
Since there is a load flow rate commensurate with the discharge amount of No., there is no need to perform an unloading operation, and since there is no rise in the temperature of the hydraulic oil, a failure judgment of the variable displacement pump 1 is made when the load flow rate disappears. I'll do it.

As described above, according to the first embodiment, the pump failure is not judged only by the abnormally high discharge pressure as in the conventional apparatus, and the unloading is temporarily performed when the discharge pressure becomes abnormally high. After the valve 14 is opened and the line pressure is returned to the normal pressure, the unload valve 14 is returned to the on-load state again and the line pressure increase speed until the abnormally high pressure is measured is measured. Since it is determined whether or not the discharge flow rate of the variable displacement pump is abnormal by determining whether or not the discharge amount of the variable displacement pump 1 is abnormal, it is possible to determine whether or not the variable displacement pump 1 is abnormal. When the line pressure is abnormally high due to the imbalance (Qp> Qv) in the flow balance between the minimum flow rate Qp and the leak flow rate Qv of the pressure control valve 9, it is possible to reliably prevent erroneous determination as a pump abnormality. This Can.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the viscosity increases due to the low temperature of the hydraulic oil in a cold region, etc.
This is suitable when the leak flow rate Qs of the pressure control valve 9 is smaller than the minimum discharge flow rate Qp of the variable displacement pump 1.
That is, in the second embodiment, as shown in FIG. 7, the temperature sensor 22 for measuring the hydraulic oil temperature of the discharge side pipe 5 is arranged between the check valve 8 and the input port 9a of the pressure control valve 9. The temperature detection value is input to the control device 19, the set pressure at which the pressure switch 15 is turned on is set to be substantially equal to the relief pressure of the relief valve 13, and the abnormality determination processing of FIG. 2 has the same configuration as that of FIG. 2 described above except that it is executed, and the same reference numerals are given to the portions corresponding to those in FIG. 2 and the detailed description thereof will be omitted.

The operation of the second embodiment will be described with reference to the flowchart of FIG. 8 in which the arithmetic processing unit 20c of the control unit 19 is used. The abnormality determination process of FIG. 8 is performed by the timer interrupt process as in the abnormality determination process of FIG. 4 described above. First, at step S21, the switch signal S of the pressure switch 15 is sent.
S is read, and then in step S22, the switch signal SS
Is ON, and when the switch signal SS is OFF, the process proceeds to step S23, the control signal CA having the logical value "0" is output to the unload valve 15, and the unload valve 15 After the on-load state is continued, the timer interrupt process is terminated and the predetermined main program is restored. When the switch signal SS is in the on state, the process proceeds to step S24.

In step S24, the temperature sensor 22
The temperature detection value T is read, and then the process proceeds to step S25 where the leak flow rate Qv of the pressure control valve 9 for which the temperature detection value T is preset is less than the minimum discharge flow rate Qs of the variable displacement pump 1 (For example, 60 ° C.) is determined. This determination is to determine whether or not the viscosity of the hydraulic oil has dropped and the leak flow rate Qv of the pressure control valve 9 has exceeded the minimum discharge flow rate Qp of the variable displacement pump 1, and when T <Ts. When it is judged that it is not possible to determine whether the discharge flow rate of the variable displacement pump 1 is abnormal due to the temperature of the hydraulic oil being too low, the timer processing is ended and the predetermined main program is returned to. When T ≧ Ts, When it is judged that the hydraulic oil temperature has reached the set temperature and the discharge flow rate of the variable displacement pump 1 is abnormal, the process proceeds to step S26.

In this step S26, the unload valve 1
4, a control signal CA having a logical value "1" is output, the unload valve 14 is held in an unload state, control of the pressure control valve 9 is stopped, and the discharge flow rate of the variable displacement pump 1 is stopped. Alarm circuit 2 for alarm signal AS indicating abnormality
2 is output to execute a predetermined alarm display and / or an abnormal process for issuing an alarm sound, and then the process ends.

In the processing of FIG. 8, step S2
The processing of 1, S22, S24 to S26 corresponds to the pump abnormality control means. According to the second embodiment, for example, when the engine is started from the parked state of the vehicle, the hydraulic oil temperature is low, the vehicle body does not swing, and the flow rate consumed by the pressure control valve 9 is only the leak flow rate. The line pressure increases due to the discharge flow rate of the variable displacement pump 1, and due to this increase in the line pressure, the discharge flow rate of the variable displacement pump 1 is gradually reduced, and finally to the minimum discharge flow rate. During this period, the line pressure has risen to the normal set pressure, but when the process of FIG. 8 is executed, the pressure switch 1
Since the switch signal SS of No. 5 is in the off state, the process proceeds to step S23, and the control signal CA of the logical value "0" is generated.
Is output to the electromagnetic solenoid 14a of the unload valve 14, so that the unload valve 14 continues in the on-load state.

At this time, since the hydraulic oil temperature is low, the minimum discharge flow rate Qp of the variable displacement pump 1 is larger than the leak flow rate Qv of the pressure control valve 9, so that the line pressure continues to rise and becomes equal to or higher than the abnormal set pressure. The switch signal SS of the pressure switch 15 is turned on. Therefore, when the process of FIG. 8 is executed, the process proceeds from step S2 to step S4,
It is determined whether or not the temperature detection value T of the temperature sensor 22 becomes equal to or higher than a preset temperature Ts.

At this time, since the engine has just been started,
The hydraulic oil temperature is approximately equal to the outside air temperature, and T <Ts
Therefore, since the timer interrupt processing is ended as it is,
The unload valve 14 continues to be in the on-load state. Therefore, the line pressure rises according to the difference between the minimum discharge flow rate of the variable displacement pump 1 and the leak flow rate of the pressure control valve 9, and when it reaches the relief pressure of the relief valve 13, the oil tank 12 passes through this relief valve 13. Returned to. In this state, the pressure energy is converted into heat by passing through the relief valve 13, so that the hydraulic oil temperature rises. This relief state continues as long as there is a difference between the minimum discharge flow rate of the variable displacement pump 1 and the leak flow rate of the pressure control valve 9.

When the discharge flow rate of the variable displacement pump 1 is normal, the relief valve 13 continues the relief state to raise the temperature of the hydraulic oil and reduce its viscosity, and accordingly the pressure control valve is increased. 9 Leak flow rate Qv
9 also increases as shown in FIG. 9, the leak flow rate Qv of the pressure control valve 9 becomes larger than the minimum discharge flow rate Qp of the variable displacement pump 1 before the hydraulic oil temperature reaches the preset set temperature Ts, which causes Since the line pressure decreases and the switch signal SS of the pressure switch 15 returns to the off state, no abnormal state is detected.

However, when an abnormality occurs where the variable displacement pump 1 is fixed to the side where the discharge flow rate is high, the line pressure will continue to rise even after the operating oil temperature reaches the set temperature Ts. When the process of FIG. 8 is executed, the switch signal SS of the pressure switch 15 is in the ON state, and the temperature detection value T of the temperature sensor 22 is the set temperature T.
s Since there is an abnormality, steps S24 to S25
After passing through step S26, the unload valve 14 is brought into an unloading state, and at the same time, step S27 is performed, control of the pressure control valve 9 is stopped, and an alarm signal AS is output to the alarm circuit 22. , A warning is displayed and / or a warning sound is emitted to warn an occupant.

Therefore, according to the second embodiment described above, unlike the conventional apparatus, the pump failure is not judged only by the abnormally high discharge pressure, and the oil temperature detection value T is detected when the discharge pressure becomes abnormally high. And the set temperature Ts are compared and judged, and when the oil temperature detection value T is lower than the set temperature Ts, when the line pressure becomes equal to or higher than the relief pressure, the relief valve is used to relieve the operating oil temperature. When the variable displacement pump 1 is normal, the leak flow rate of the pressure control valve 9 increases as the temperature of the hydraulic oil increases, so that the line pressure naturally decreases and becomes equal to or lower than the normal set pressure, and an abnormal determination is performed. However, if an abnormality occurs in which the variable displacement pump 1 is fixed in a state where the discharge flow rate is high, the oil temperature detection value T exceeds the set temperature Ts, and it is determined that the variable displacement pump 1 is abnormal. Can

In each of the above embodiments, the case where the pressure control valve 9 is applied as the control valve has been described.
The present invention is not limited to this, and other control valves such as a servo flow control valve may be applied. Further, in each of the above embodiments, the case where the load side of the variable displacement pump is the hydraulic control system of the active suspension has been described, but the present invention is not limited to this and the present invention can be applied to other hydraulic control systems. The present invention can be applied not only to the hydraulic control system but also to a fluid pressure control system such as water.

[0052]

As described above, according to the control device for a variable displacement pump according to claim 1, the unload valve is opened when the pressure detecting means detects that the line pressure becomes abnormally high. As a condition, the variable displacement pump is unloaded, and when the line pressure returns to normal pressure,
Return the unloading valve to the on-load state, measure the rising speed until the pressure detection means reaches the abnormally high line pressure, and if the rising speed exceeds the predetermined set speed, Since it is determined that the variable displacement pump has failed and the discharge flow rate is increasing, and when the rising speed is lower than the set speed, the variable displacement pump is judged to be normal. Abnormal line pressure Since it is not possible to judge a pump failure only by detecting high pressure,
It is of course possible to reliably detect an abnormality in the variable displacement pump that increases the discharge amount, and the discharge pressure may be abnormally high due to an imbalance in the flow balance between the minimum flow rate of the variable displacement pump and the leak flow rate of the pressure control valve. In such a case, it is possible to obtain an effect that an accurate abnormality determination can be performed without erroneously determining that the variable displacement pump is abnormal.

Further, when the control device for the variable displacement pump according to the second aspect detects that the line pressure becomes abnormally high by the pressure detection means, the temperature of the hydraulic oil detected by the temperature detection means and a predetermined setting. If the temperature of the hydraulic oil falls below the oil temperature setting value, the discharge flow rate of the variable displacement pump is relieved via the relief valve without misjudgeting that the discharge flow rate of the variable displacement pump is abnormal. This raises the hydraulic oil temperature, and if this causes the leak flow rate of the control valve to exceed the minimum discharge flow rate of the variable displacement pump, it is judged as normal, but when the hydraulic oil temperature exceeds the set temperature, the variable displacement It is possible to determine that the pump is abnormal, and it is possible to accurately determine the abnormality of the variable displacement pump without making an erroneous determination as in the control device for a variable displacement pump according to claim 1. It is.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a basic configuration of the present invention,
(A) is a schematic block diagram corresponding to claim 1, (b) is a schematic block diagram corresponding to claim 2.

FIG. 2 is a hydraulic system diagram showing a first embodiment of the present invention.

FIG. 3 is a diagram showing an operation of the pressure switch according to the present invention.

FIG. 4 is a flowchart showing an example of an abnormality determination processing procedure of the control device according to the first embodiment of the present invention.

FIG. 5 is a time chart used for explaining the operation during traveling of the first embodiment of the present invention.

FIG. 6 is a time chart used for explaining the operation of the first embodiment of the present invention when the vehicle is stopped.

FIG. 7 is a hydraulic system diagram showing a second embodiment of the present invention.

FIG. 8 is a flowchart showing an example of an abnormality determination processing procedure of the control device according to the second embodiment of the present invention.

FIG. 9 is a diagram showing a minimum flow rate of a variable displacement pump and a leak flow rate of a pressure control valve due to a temperature change of hydraulic oil.

FIG. 10 is a hydraulic system diagram showing a conventional example.

[Explanation of symbols]

 1 Variable Capacity Pump 4 Throttle Valve 5 Discharge Side Piping 8 Check Valve 9 Pressure Control Valve 10 Hydraulic Cylinder 12 Oil Tank 13 Relief Valve 14 Unload Valve 15 Pressure Switch 19 Controller 22 Alarm Circuit 25 Temperature Sensor

Claims (2)

[Claims] 1. A variable displacement pump that supplies a working fluid to one end of a supply-side pipe with a minimum flow rate regulated, a fluid-operated device that is connected to the other end of the supply-side pipe through a control valve, A line pressure abnormality detecting means for detecting that the line pressure of the supply side pipe is in an abnormal state, and a line pressure control means for suppressing the line pressure when the line pressure abnormality detecting means detects the line pressure abnormal state. In the control device for the variable displacement pump, the line pressure control means includes an unload valve disposed on the discharge side of the variable displacement pump,
When the line pressure abnormality detecting means detects the line pressure abnormality state, the unload valve is set to the unload state,
And a valve control means for releasing the unloading state when the line pressure returns to a normal value, and a line pressure detection value of the line pressure detecting means for releasing the unloading state of the unload valve by the valve control means. Rising speed measuring means for measuring the line pressure rising speed based on the above, and when the line pressure rising speed of the rising speed measuring means is equal to or more than a set value, it is judged that the variable displacement pump is in an abnormal state and the unloading is performed. A control device for a variable displacement pump, comprising: a pump abnormality control means for controlling a valve to an unloading state. 2. A variable displacement pump that supplies a working fluid to one end of a supply-side pipe with a minimum flow rate regulated, a fluid-operated device connected to the other end of the supply-side pipe through a control valve, A line pressure abnormality detecting means for detecting that the line pressure of the supply side pipe is in an abnormal state, and a line pressure control means for suppressing the line pressure when the line pressure abnormality detecting means detects the line pressure abnormal state. In the control device for the variable displacement pump, the line pressure control means includes a relief valve and an unload valve arranged in parallel on the discharge side of the variable displacement pump, and a temperature of the working fluid discharged from the variable displacement pump. When the abnormal line pressure state is detected by the line pressure abnormality detection unit and the temperature detection value of the temperature detection unit is equal to or higher than a set value, the variable displacement pump A control device for a variable displacement pump, comprising: pump abnormality control means that determines that the unload valve is in an abnormal state and controls the unload valve to an unload state.