JP2612699B2 - Control device for judging malfunction of fluid actuator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for judging a malfunction of a fluid actuator used in a construction machine or the like.

2. Description of the Related Art Conventionally, in a crane device of a construction machine, the supply of pressure oil to a load of a hydraulic motor or the like driving the crane and the direction of the supply are performed by operating a fluid switching valve.

When remotely controlling such a load control fluid switching valve, a method of operating the fluid switching valve by a remotely controlled fluid actuator is employed.

This remote control is based on a known feedback control in which a feedback signal indicating the actual position of the fluid actuator follows a command signal indicating an operation position of the fluid actuator.

If a malfunction occurs in such feedback control, the remote control is stopped by, for example, unloading the fluid pressure source that supplies the pressure fluid to the load,
Operational safety is ensured.

In this case, the malfunction is determined when the command signal is set to the neutral position and the value of the feedback signal has not yet reached a value corresponding to the neutral region, the command signal is set to the neutral position. From the time when the neutral position is set, it is determined whether or not the elapsed time exceeds a reference time having a predetermined fixed time width, and if it is determined that the reference time has exceeded the reference time, a command is issued. The malfunction is determined assuming that the feedback value does not normally follow the value.

In addition, when the device to be controlled includes a hydraulic control part, the oil temperature immediately after the start is very low and the viscosity of the pressure oil is very low in a low temperature condition such as a cold region. The response of the hydraulic control becomes very slow. In such a case, the oil temperature is raised to an appropriate temperature by warming up the device.

In this case, in a state where the control response during the warm-up is slowed down, if the reference time in the malfunction determination is shortened, the response speed of the control is slowed down. A malfunction is determined, and the control system stops the device. In view of the above, in consideration of a control response slowdown in a range where such a decrease in oil temperature can normally occur,
In the determination of the malfunction, when the feedback signal does not follow the command signal after the “reference time that has become a certain time” having a time width equal to or longer than the control response slowdown, a malfunction occurs. And stop the device.

[Problems to be Solved by the Invention] However, as in the conventional malfunction determination, the reference time for the malfunction determination is set to be a sufficiently long fixed time period in consideration of the case where the control becomes slow due to a decrease in oil temperature or the like. In other words, it is impossible to judge a malfunction unless the long reference time has elapsed even after the control oil temperature has reached an appropriate temperature, and the time required to judge the malfunction and stop the device is longer than necessary. It will be a long time.

In response to this, particularly in the operation of a crane or the like that requires a high level of safety, it is necessary to perform a malfunction determination as soon as possible and to stop the device in an emergency.

An object of the present invention is to provide a control device for determining a malfunction of a fluid actuator which has solved the above-mentioned problems.

[Means for Solving the Problems] Displacement chambers (1a, 1b) are provided on both axial sides of a piston interlocked with a fluid switching valve (5) for controlling a fluid supply amount and a supply direction to a load (6). Provided to form a fluid actuator (1), wherein solenoid valves (2, 3) selectively pump fluid to one of the displacement chambers and to the other. Each of the switching positions opened to the reservoir is provided, and each time a deviation occurs between the value of the command signal indicating the operating position of the piston and the value of the feedback signal detecting the actual operating position of the piston, a single operation is performed. During the application time of one pulse, the solenoid valve is driven, fluid is pumped to the displacement chamber on the side selected in the direction in which the deviation is corrected among the two displacement chambers, and the deviation is corrected, and the single pulse is applied. of The application time width (tn) is proportional to the basic application time (to) corresponding to the time required for the fluid pressure in the displacement chamber to reach the minimum value required to activate the piston by the fluid pumping, and to the deviation. Correction application time (te), and each time the deviation is corrected by the single pulse signal,
For the basic application time width, if the drive is insufficiently driven, a time width proportional to the shortage is added.If the control is overdriven, the time width proportional to the excess is reduced. In the control device to be modified, when it is determined that the value of the command signal is a neutral value, the value of the feedback is not a neutral value even if a predetermined reference time has passed from the determination. The fluid supply to the load is stopped, and the predetermined reference time is a time proportional to the corrected latest basic application time.

[Examples] Hereinafter, the present invention will be described based on examples.

FIG. 1 is a system diagram showing a hydraulic switching valve control device as an embodiment for describing a control device for judging a malfunction of a fluid actuator according to the present invention.

In FIG. 1, a hydraulic switching valve 5 as a fluid switching valve for hydraulically controlling the operation of a hydraulic motor 6 as a load.
Has a switching position 5a, 5b and 5c, and the switching position is operated by a hydraulic actuator 1 or a lever 1c as a fluid actuator, and pressurized oil is supplied to a displacement chamber 1a or 1b in the hydraulic actuator 1. Alternatively, the elimination is performed by operating the switching valve 2 or 3 as a solenoid valve.

By operating the lever 10i, the signal generator 10a
The voltage signal is transmitted to the wiring 10b. The voltage signal is a command signal for instructing the position of the piston 1d in the hydraulic actuator 1.
Input to the electronic control unit 10 via b.

Output wirings 10g and 10h in the electronic control unit 10 are input to solenoids 3d and 2d, respectively.

The movement of the piston 1d, that is, the movement of the hydraulic switching valve 5 is detected by the potentiometer 5d, and the output wiring 10e for transmitting the detected signal is the wiring of the feedback signal in the electronic control unit 10.

The circuit configuration of the electronic control unit 10 is as shown in FIG. 4, which is shown by a block diagram.

In FIG. 4, 10A is a detection storage unit, 10B is a deviation calculation unit, 10C is a drive determination unit, 10E is an allowable deviation setting unit,
F is basic time change storage means, 10J is pulse width calculation means, 10
K is basic time selection means, 10L is FB reference value setting means and 10L
M indicates an output transistor.

The operation of the hydraulic switching valve control device shown in FIGS. 1 and 4 will be described below.

The hydraulic motor 6 is driven by hydraulic power from the hydraulic power source 4 switched by the hydraulic switching valve 5, and when the hydraulic switching valve 5 is located at the switching position 5b, the flow of the hydraulic power is closed and the hydraulic motor 6 Is stopped.

On the other hand, when the switching position of the hydraulic switching valve 5 is located at 5a or 5c, the hydraulic power is sent to one or the other of the hydraulic motor 6 to drive the hydraulic motor 6 to one or the other.

The hydraulic motor 6 drives a crane (not shown).

Such operation of the hydraulic switching valve 5 is performed by the operation of the hydraulic actuator 1, and the operation of the hydraulic actuator 1 is as follows.

The switching valves 2 and 3 are in their respective switching positions as shown.
When set to 2b and 3b, both the displacement chambers 1a and 1b are opened to the respective reservoirs, and the hydraulic actuator 1 is in a completely free state.

Therefore, when the driver operates the lever 1c in this state, the piston 1d of the hydraulic actuator 1 can be freely operated, and the operated piston 1d operates the hydraulic switching valve 5.

In this way, by manually operating the lever 1c, the switching position 5a, 5b or 5c can be arbitrarily selected, and the operation can be performed by the driver in the driver's seat. I have.

In the hydraulic actuator 1, a piston 1d connected to the lever 1c is provided with a spring in the hydraulic switching valve 5.
Since the centering action is performed by 5e and 5f, when the driver releases his hand from the lever 1c in this state, the hydraulic actuator 1 sets its switching position to 5b (neutral position).

In order to operate the hydraulic actuator 1 remotely in response to such a manual operation, the solenoid 2d or 3d is driven, and the switching valve 2 or 3 is operated by the drive, and the operated switching valve 2 or 3 is operated. The hydraulic actuator 1 will be operated.

Here, the switching valve 2 or 3 is the hydraulic actuator 1
The operation of operating is as follows.

When it is desired to fix the piston 1d of the hydraulic actuator 1 at an arbitrary position, the switching valves 2 and 3 are set to the switching position 2a and the switching position 3a, respectively.

When the switching positions of the switching valves 2 and 3 are set in this manner, the pressure oil from the hydraulic pressure source 4 is supplied to the double displacement chambers 1a and 1b.
The check valves 2c are respectively provided at the inlet portions of the switching valves 2 and 3 to which the pressure oil is pumped.
And 3c, the movement of the piston 1d is fixed in the hydraulic actuator 1.

In this state, since the hydraulic pressure from the hydraulic pressure source 4 is guided to both the displacement chambers 1a and 1b, the hydraulic pressure acts on the piston 1d from both sides thereof.

When only the switching valve 2 is set to the switching position 2b from such a state, the operating oil pressure in the displacement chamber 1a is released to the reservoir 7 through the switching valve 2, so that the piston 1d operates in the displacement chamber 1b. 1 is pressed downward, and the pressing shifts the switching position in the hydraulic switching valve 5 to the side of 5a.

Conversely, from the state where the piston 1d is fixed,
When only the switching valve 3 is set to the switching position 3b, the displacement chamber 1b
Is released to the reservoir 7 via the switching valve 3, the hydraulic pressure in the displacement chamber 1a is
1d is pushed upward in FIG. 1 to shift the switching position of the hydraulic switching valve 5 to the switching position 5c.

Solenoid 2d driven and controlled by electronic control unit 10
And 3d are controlled by signal application consisting of the sum (to + te) of the basic application time to and the correction application time te transmitted from the electronic control unit 10, and the basic application time to and the correction application time te Derives from the following needs:

Since the urging force of the springs 5e and 5f in the hydraulic switching valve 5 is also interlocked with the piston 1d, the spring urging force acts directly inside the piston 1d, and the hydraulic actuator shown in FIG. By replacing 1 with the configuration shown in FIG. 2, the hydraulic pressure required for the piston 1d to be properly operated by operating the switching valve 2 or 3 can be explained.

In the hydraulic actuator 1 shown in FIG. 2 for explanation, a piston 1d is fitted to the cylinder 1e so as to be slidable in the axial direction, and springs 5e and 5f are fitted to the piston 1d in the axial direction. The two biasing forces act in directions opposing each other, and the action of the two biasing forces is such that the piston 1d is set to the neutral position n when no external force acts on the piston 1d.

In the configuration shown in FIG. 2, when the piston 1d shifts from the neutral position n to the right by a distance x as shown in the drawing, an axial force of approximately k1 · x acts on the piston 1d to the left. You are doing. Note that k1 is a spring constant of the spring 5f.

Therefore, the starting force required for the piston 1d to move further rightward from this position requires approximately k1 · x.

Conversely, the starting force when the piston 1d moves further leftward from this position is a value driven by k1 · x.

In contrast to the above case, when the piston 1d is located at a distance of x to the left from the neutral position n, the force required to activate the piston 1d when the piston 1d moves further left from that position. Is approximately k2 · x. Here, k2 is a spring constant of the spring 5e.

Also, from the position of the piston 1d, the piston 1d
Is a value driven by the k2 · x.

That is, the types of starting force required for the piston 1d are arranged as follows.

When the piston 1d is located to the right from the neutral position n, 1) when the piston 1d tries to move in the direction of the arrow a1, and 2) when the piston 1d tries to move in the direction of the arrow a2. In the case where the piston 1d is located to the left from the neutral position n, 1) when the piston 1d tries to move in the direction of the arrow a3, and 2) when the piston 1d is in the direction of the arrow a4. There are two cases when trying to move in the direction of.

As a result, in FIG. 2, there are four basic types of force required for the piston 1d to start in any direction from any of its fixed positions.

With respect to these four types of starting forces, the relationship between the starting force required for the piston 1d and the operating oil pressure of the displacement chamber 1a or 1b required for the starting will be examined.

Taking the case where the piston 1d is actuated from the position shown in FIG. 2 in the direction of arrow a1 as an example, the force required for the actuation is k1 · x as described above.

On the other hand, in order to start the piston 1d by hydraulic pressure, the piston 1d is started by the differential pressure dp between the operating oil pressure generated in the displacement chamber 1a and the operating oil pressure generated in the displacement chamber 1b.

When such a differential pressure dp is generated by driving the above-described switching valve 2 or 3, and the switching valve 2 or 3 is driven by a single pulse signal having a finite time width, the phenomenon that the differential pressure dp occurs is as follows. It looks like this:

As described above, in order for the piston 1d to be fixed at the position shown in FIG. 2, the switching valves 2 and 3 in FIG.
Are set at the switching position 2a and the switching position 3a, respectively.

When the piston 1d is started from the fixed position of the piston 1d in the direction of arrow a1, only the switching valve 3 is set to the switching position 3b, and the switching position of the switching valve 2 is kept at 2a. In the method of setting 3 to the switching position 3b, a single pulse signal Vo as shown in FIG. 3 in a pattern in which the solenoid 3d is turned off is transmitted to the solenoid 3d.

In FIG. 3, the horizontal axis t indicates elapsed time, the vertical axis V indicates the output voltage of the pulse signal Vo or Ve, and the vertical axis p
Indicates the hydraulic pressure of the working hydraulic characteristic pao or pae.

In this case, at the moment when the solenoid 3d is turned off, the operating oil pressure p in the displacement chambers 1a and 1b is almost equal to the oil pressure in the oil pressure source 4 at pm.

When the time t elapses from this state (t = 0 in FIG. 3), the operating oil pressure p in the displacement chamber 1b is increased because the displacement chamber 1b is opened to the reservoir 7 through the switching valve 3 in FIG. T = to, like the hydraulic pressure characteristic pao at
Then, the pressure is reduced toward p = 0 as the time t elapses.

However, since the voltage of the pulse signal Vo is turned on again at t = to, the switching position of the switching valve 3 becomes 3a, and the pressure oil in the hydraulic pressure source 4 is transmitted to the displacement chamber 1b again, As shown in the working hydraulic pressure characteristic pao, the pressure increases thereafter toward p = pm.

For this reason, when the pulse signal Vo is transmitted to the solenoid 3d, the maximum decrease in the working oil pressure difference between the displacement chamber 1b and the displacement chamber 1a becomes dp = dpo
Becomes In this case, when the value obtained by multiplying the value of the pressure difference dpo by the cross-sectional area of the cylinder 1e corresponds to the above-mentioned value of the starting force k1 · x, the application time to the solenoid 3d for generating this starting force is the third. This is the basic application time to in the figure.

Further, the value of the basic application time to has to be selected in each of the cases of the arrows a1, a2, a3 and a4 as described in FIG.

However, the pressure difference dp caused by this basic application time to
o is the minimum value required to start moving the piston 1d.

Therefore, in order to actually move the piston 1d, the application time (to
+ Te), the resulting pressure differential must be dpo + dpe.

That is, of dpo + dpe, the pressure difference dpe is the piston 1d
Is a hydraulic component necessary for accelerating the signal, and the correction application time te in this case is a value proportional to a signal deviation between a wiring 10b and an output wiring 10e described later.

The working oil pressure characteristic of the pressure difference dpo + dpe is indicated by pae in FIG.

The above solenoids 2d and 3d are connected to the electronic control unit 10
The control driven by the control is as follows.

In FIG. 1, when an operator operates a lever 10i, an analog voltage signal is generated on a wiring 10b, and the signal is input to a detection storage unit 10A in FIG.

A potentiometer that detects the position of the piston 1d
The signal from 5d is input to the detection storage means 10A as a signal of an analog amount via the wiring 10e.

The calculation in FIG. 4 after input to the detection storage means 10A is as follows.

Operation in the detection storage means 10A: The command signal on the wiring 10b and the feedback signal on the wiring 10e are sequentially AD-converted (converted from an analog value to a digital value) by switching in a multiplexer provided in the detection storage means 10A. The converted command signal value cs and feedback signal value cf are respectively temporarily stored in the RAM.

Calculation in deviation calculating means 10B: Calculates deviation Er, Er = cs-cf between signal value cs and feedback signal value cf.

Operation in the drive determination means 10C: The deviation Er and the allowable deviation Ero are compared to determine whether a negative drive pulse signal should be output to the wiring 10g or 10h.

The determination in this case will be specifically described as follows.

Feedback signal value cf (actual position of piston 1d)
Is greater than the command value cs, a deviation Er occurs,
And, when the deviation Er is larger than the allowable deviation Ero, it is determined that the position of the piston 1d is delayed. When the feedback signal value cf is behind the command value cs, the deviation Er is generated, and the deviation Er is allowable. deviation
When the difference is larger than Ero, it is determined that the position of the piston 1d is advanced. When the difference Er is smaller than the allowable difference Ero, it is determined that the control is satisfied, and the piston 1d is fixed at the position.

The allowable deviation Ero is a value stored in the allowable deviation setting means 10E.

Calculation in the basic time change storage means 10F: This means that the piston 1d starts to start in any direction of the arrow a1, a2, a3 or a4 described in FIG. Each basic application time to which is determined depending on the existence is stored.

Each stored basic application time to is corrected as described below.

That is, if the control is insufficiently driven or excessively driven as a result of using any necessary basic application time to, the basic application time to is corrected by the above-described deviation Er.

That is, the new basic application time to is the same as the previous basic application time to, and when the drive is insufficient, a portion proportional to the shortage (deviation) is added.
The amount proportional to the excess (deviation) is reduced.

Calculation in basic time selection means 10K: This calculation is the fifth
The calculation of the flowchart in the figure is performed.

 Hereinafter, the flowchart in FIG. 5 will be described.

Calculation A1: The calculation in the basic time selection means 10K is started.

Arithmetic A2: It is determined whether the feedback signal value cf is greater than or equal to the feedback reference value cfo.

Here, the value of the feedback reference value cfo is
d is a value corresponding to the feedback signal value cf when located at the neutral position n in FIG. 2, and the feedback reference value cfo is a value stored in the FB reference value setting means 10L.

Therefore, the determination in the operation A2 indicates that the piston 1d
That is, it is determined whether or not it exists on the right side in FIG. 2 including the neutral position n.

Arithmetic A3: Command value when the judgment in arithmetic A2 is Yes
It is determined whether cs is greater than the feedback signal value cf.

Arithmetic A4: When the determination in arithmetic A3 is Yes, this means that the piston 1d is instructed to move in the direction a1 in FIG.
Set to 1.

Arithmetic A5: When the determination in arithmetic A3 is No, this means that the piston 1d is instructed to move in the direction a2 in FIG.
Assume 2.

Arithmetic A6: When the judgment in arithmetic A2 is No, output value c
It is determined whether or not s is larger than the feedback signal value cf.

Arithmetic A7: When the determination in arithmetic A6 becomes Yes, this means that the piston 1d is instructed to move in the direction a4 in FIG.
And 4.

Calculation A8: When the determination in calculation A6 is No, this means that the piston 1d is instructed to move in the direction a3 in FIG.
Assume 3.

The basic application time of each of to1, to2, to3, and to4 is, as described above, the basic time change storage unit 10.
It is the one stored in F.

Arithmetic A9: The arithmetic operation is returned to the arithmetic operation of the pulse width calculating means 10J, and in this case, the basic application time to which is calculated in any one of the arithmetical operations A4, A5, A7 and A8 and is equivalent to the current state is output to the pulse width calculating means 10J. I do.

Calculation in pulse width calculation means 10J: When the drive determination means 10C determines that the hydraulic actuator 1 needs to be driven as described above, the following calculation in this means is started.

The correction application time te = b · Er and the application time tn = to + te are calculated using the deviation Er calculated by the above-described deviation calculation means 10B, and the application time tn is output to the output transistor 10M.

Here, b is a proportional constant, and to is the basic application time to output from the above-described calculation A9.

Calculation in output transistor 10M: output transistor 1
At 0M, there are respective transistors Tr1 and Tr2 for turning on and off the voltages on the wirings 10g and 10h, respectively.

When the transistor Tr1 transmits a single negative pulse signal (corresponding to the pulse signal Ve in FIG. 3) only to the wiring 10g and the voltage of the wiring 10h remains ON, as described above, The piston 1d moves upward in FIG. 1. Conversely, when the transistor Tr2 sends a single negative pulse signal only to the wiring 10h and the wiring 10g remains on, the piston 1d Is shifted downward in FIG.

In such a configuration, output transistor 10M performs the following operation.

1) When the content of the deviation Er in the deviation calculation means 10B indicates that the piston 1d should be further moved upward in FIG. 1, the transistor Tr1
Only emits a single negative pulse signal Ve on line 10g.

2) When the content of the deviation Er in the deviation calculating means 10B is such that the piston 1d should be further shifted downward in FIG. 1, the transistor Tr2
Only the negative single pulse signal Ve is transmitted to the wiring 10h.

In this case, the application time tn for transmitting the single negative pulse signal is the application time tn output from the pulse width calculation means 10J.

3) If the deviation calculation means 10B determines that the deviation Er is smaller than the allowable deviation Ero and the control is satisfied, both the transistors Tr1 and Tr2 are connected to the wiring 10g.
And the voltage at 10h is left on. As a result, the piston 1d remains fixed at that position.

The above operation is an operation when the device in FIG. 1 is in a normal state.

On the other hand, the electronic control unit 10 determines whether the malfunction has occurred in response to the command signal from the lever 10i due to the failure of the hydraulic circuit or the like in FIG. Every time you send, go.

FIG. 6 shows a flowchart for determining the malfunction, and the operation of FIG. 6 will be described below.

Operation B0: Start operation.

Operation B1: Initialize the operation.

Arithmetic B2: At the start of operation, when the power is turned on and the lever 10i is still in the neutral state without being operated, if the signal value output to the wiring 10b has drifted from the neutral value, Compensate for drift.

Arithmetic B3: Detect a command value of lever 10i (corresponding to command value cs).

Arithmetic operation B4: A feedback value (corresponding to a feedback signal value cf) from the output wiring 10e is detected.

Calculation B5: Calculate the deviation Er = cs−cf.

Operation B6: It is determined whether or not the absolute value of the deviation is smaller than a predetermined Ero, that is, whether or not the deviation Er is within an allowable range.

If the determination in operation B6 is yes, it is determined that the operation has been performed according to the command, and that the deviation is within the allowable value.
Return to

Calculation B7: When the determination in calculation B6 is no, that is, when there is a deviation Er, the hydraulic device does not operate according to the command, and it is determined that a malfunction may have occurred. I do.

Here, the detection of this malfunction is based on the subroutine flowchart shown in FIG.

 Hereinafter, the operation of FIG. 7 will be described.

Computation C0: Starts malfunction detection computation.

Calculation C1: It is determined whether or not the command value from the lever 10i in FIG. 1 is neutral.

Arithmetic C2: When the determination in the arithmetic C1 is yes, it is determined whether or not the value of the feedback signal from the output wiring 10e in FIG. 1 indicates a value corresponding to the neutral position.

Arithmetic C3: When the determination in the arithmetic C2 is no, it is determined whether or not the feedback value FB is larger than the feedback value FBn corresponding to the neutral position n in FIG.

 This means the following.

In the judgment of calculation C1, the command value is neutral,
The fact that the feedback value was not neutral in C2 means that the driver stopped the hydraulic motor 6 for the purpose of
Returning the lever 10i in FIG. 1 to the neutral position, thereby operating the hydraulic switching valve 5 to set the switching position to the switching position 5b, the feedback detection value of the potentiometer 5d has not yet returned to the neutral position. Means This also means that the switching valves 2 and 3,
This means that there is a possibility that one of the hydraulic actuator 1 and the hydraulic switching valve 5 does not operate according to the command value due to a cause such as a twist.

The fact that the feedback value FB is larger than the feedback value FBn corresponding to the neutral position n means that it is determined whether the hydraulic switching valve 5 or the hydraulic actuator 1 is on the right side of the neutral position n in FIG. doing.

That is, in this determination, if yes, the piston 1d is on the a1 side in FIG. 2, and if no, it means that the piston 1d is on the a3 side.

Arithmetic C4: If the determination in arithmetic C3 is yes, the basic application time to1 on the a1 side is multiplied by a constant A, and this is set as a reference time tc for determining whether or not a malfunction has occurred.

Arithmetic C5: When the determination of the arithmetic C3 is no, the basic application time to3 on the a3 side is multiplied by a constant A, and this is set as a reference time tc.

Arithmetic C6: The elapsed time tci after the command value is determined to be set to neutral in the arithmetic C1 is compared with the reference time tc. If tci <tc, no is set, and conversely, tci> tc is yes.
Is determined.

 This means the following.

Even if the feedback value has not yet returned to the neutral position with respect to the command value in the time lapse range where tci <tc, to judge this as a malfunction, monitor the feedback value to return to the neutral position n. Means that it is better to perform the operation, and within the time lapse range of tci> tc, the elapsed time since the determination that the value of the command signal has returned to the neutral position
Even after tci has passed the reference time tc or more, the feedback value has not yet returned to the neutral position, which means that it is determined that a malfunction has occurred in the control due to some cause. .

Further, in this case, the reference time tc is set in each operation direction (a1
The setting of the basic application time to in the direction a3) is based on the following reason.

As described in FIGS. 4 and 5 described above,
The basic application time to is updated for each deviation Er resulting from driving in the a1 direction or the a3 direction in FIG. 2 in view of the deviation Er. Therefore, the basic application time to1 or the basic application time to3 in the operation C4 or the operation C5 is the latest data updated at the end. Alternatively, when the voltage applied to the solenoid 3d is low, the hydraulic response via the switching valve 2 or 3 is slowed down, and as a result, the basic application time
Has a relatively long time span.

In this way, the basic application time should be
Since such a response may be long, if such a response is normally dull, the reference time tc is increased, and as a result, the reference time tc is made a function of the basic application time to. Is what it is.

Here, the basic application time to is used without using the basic application time to in a2 or a4 at the time of return in FIG.
The basic application time to in the case of a1 or a3 is used.

This is because the current malfunction is determined by calculation C1 and calculation C2.
As can be understood from the calculation of FIG. 2, the state in which the hydraulic motor 6 is being stopped, that is, in FIG.
1d determines whether or not a malfunction has occurred in a state where it should operate in the direction of a2 or a4. Therefore, if a malfunction has occurred in the current movement of the piston 1d in the a2 or a4 direction, the basic application time to in that state has already become a completely random value causing the malfunction. There should be.

On the other hand, the fact that the piston 1d is about to return to the neutral position n, at least at present, should have been moving in the normal a1 or a3 direction just before that. Therefore, the basic application time to immediately before the operation toward the neutral position n where the malfunction is considered to have occurred, that is, the latest basic application time to in the a1 or a3 direction immediately before the return operation is used. Is what it is.

In addition, this erroneous operation may occur abruptly, but may also cause the piston 1d or the like to gradually deteriorate its movement. Therefore, considering such a case, the reference time tc is not a function of the basic application time to immediately before the rightward operation or the leftward operation as described above, but the application time is (to + te). When the error Er is corrected to zero by one single pulse signal transmission,
This may be a function of the latest basic application time to.

Further, the calculations in the calculations C1 and C2 have a problem in a case where the hydraulic motor 6 is about to be stopped. This is most dangerous when a malfunction occurs and it is necessary to stop the hydraulic motor 6. The stopping of the hydraulic motor 6 (that is, the operation of the crane or the like (Stop motion).

For this reason, in this subroutine, the malfunction is determined only when the hydraulic motor 6 is stopped.

However, not only in the case where the hydraulic motor 6 is stopped, but also in the case where it is determined that a malfunction has occurred, the calculation in the calculation C1 and the calculation C2 is performed in accordance with whether the deviation Er is within a predetermined deviation range. Is replaced with a judgment,
Then, it may be determined whether or not the feedback value follows a given command value within a predetermined reference time.

Arithmetic C7: If the determination in arithmetic C6 is yes, a flag is set as a sign of malfunction.

Operation C8: The operation returns to the operation B7 of the main routine in FIG.

When the determination in the calculation C1 of FIG. 7 is no, in this case, the flag is cleared in the calculation C9 and the main routine of FIG. Return, the judgment in operation C2 is
If the answer is yes, the feedback value is neutral as instructed in the calculation C1, and in this case, the control is operating normally.
In FIG. 6, the flag is cleared, and the process returns to the main routine of FIG. 6 via operation C8. When the determination in operation C6 is no, the reference time tc has not yet elapsed since the neutral instruction in operation C1. In operation C9, the flag is cleared, and the process returns to the main routine via operation C8.

Returning from the subroutine of FIG. 7 to the main routine of FIG. 6 again.

Arithmetic operation B8: The malfunction detection of the arithmetic operation B7 is determined by the subroutine of FIG. 7, and as a result, it is determined whether or not the malfunction has occurred, that is, whether or not the flag has been set.

Operation B9: When the determination in operation B8 is no, that is, when the malfunction flag is not set, the operation B9
Then, the normal control for driving and controlling the switching valve 2 or 3 in FIG. 1 is performed through the following calculations B10 and B11. The operations of the operations B9, B10 and B11 are performed in the fourth
The normal control shown in FIG. 5 and FIG. 5 is performed.

Operation B12: In the operation B8, when the determination is yes, the hydraulic circuit of the hydraulic motor 6 is unloaded, for example,
An abnormal measure for stopping the operation of the hydraulic motor 6 is taken.

Operation B13: Simultaneously with the abnormality treatment, an indicator light indicating the abnormality is turned on to notify the abnormality.

As described above, the present invention controls and modifies the operation position of the fluid actuator 1 by the deviation during the single pulse application time tn every time a deviation between the command value and the feedback value occurs, and the application time tn becomes longer. , Based on the control of the configuration consisting of both components of the basic application time to and the correction application time te.

According to the present invention based on such control, when the control is excessive or deficient for each of the basic application times to, the amount in proportion to the excess or deficiency is corrected (the basic time change in FIG. 4). The storage means 10F) uses the control to be performed.

Then, the feature of the present invention is that when it is determined that the feedback value has not yet reached the neutral value even when the predetermined reference time tc has passed after the command value became neutral, this is determined to be a malfunction ( The operation C6) is at a point where the predetermined reference time tc is a time proportional to the corrected latest basic application time to (operations C4 and C5).

[Effects of the Invention] In the control of the present invention, the malfunction is determined if the response of the control is slowed down due to a decrease in the fluid temperature or a decrease in the voltage for driving the solenoid valves 2 and 3, and the like. In the normal control response speed after warm-up, etc., the malfunction can be judged as quickly as possible without wasting time in the normal control response speed after warm-up, etc. You can do it.

Further, in the malfunction determination of the present invention, the command value is returned to the neutral position in response to the danger that the control system may fail when the user feels danger in the operation of the crane or the like and immediately stops the operation. It is intended for cases.

This means that if a crane or the like is stopped for safety, if a malfunction occurs, it is possible to stop the operation of the load such as the hydraulic motor as a fail safe as soon as possible. As a result, the safety of operation is further improved.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a hydraulic switching valve control device for implementing a control device for judging malfunction of a fluid actuator according to the present invention, and FIG. 2 is a skeleton diagram showing a hydraulic actuator 1 in FIG. FIG. 3 is an explanatory view, and FIG. 3 is a diagram showing an operating hydraulic characteristic pao or pae of the displacement chamber 1a or 1b in FIG.
FIG. 4 shows the characteristics of each of the pulse signals Vo and Ve transmitted from the electronic control unit 10 shown in FIG.
FIG. 5 shows a flowchart of the basic time selecting means 10K in FIG. 4, and FIG.
The figure shows a flowchart of the malfunction determination of the control system in FIG. 1, and FIG. 7 shows the flowchart of the subroutine in FIG. The reference numerals used in the examples are as follows. 1: hydraulic actuator, 1a and 1b: displacement chamber, 1c: lever, 1d: piston, 1e: cylinder, n: neutral position, 2 and 3: switching valve, 2a, 2b, 3a and 3b: switching position, 2d and 3
d: solenoid, 4: hydraulic source, 5: hydraulic switching valve, 5a, 5b and
5c: Switching position, 5d: Potentiometer, 6: Hydraulic motor, 7:
Reservoir, 10: electronic control unit, 10a: signal generator, 10b, 10
e, 10g and 10h: electric wire, 10i: lever.

Claims (1)

(57) [Claims] A displacement chamber (1a, 1b) is provided on each axial side of a piston interlocked with a fluid switching valve (5) for controlling a fluid supply amount and a supply direction to a load (6). 1) forming a solenoid valve (2, 3)
Has a switching position for selectively pumping fluid to one of the displacement chambers and opening the displacement chamber on the other side, and indicating an operating position of the piston. Each time a deviation occurs between the value of the command signal to be performed and the value of the feedback signal that has detected the actual operation position of the piston, the solenoid valve is driven for the duration of the single pulse to drive the solenoid valve. The deviation is corrected by fluid pressure feeding to the displacement chamber on the side selected in the direction in which the deviation is to be corrected among the displacement chambers, and the application time width (tn) of the single pulse is changed by the fluid pressure feeding to the fluid in the displacement chamber. Basic application time (to) corresponding to the time until the pressure reaches the minimum value required to activate the piston
And the correction application time (te) in proportion to the deviation. Whenever the deviation is corrected by the single pulse signal, the control is insufficient for the basic application time width. In the case of a control device that adds a time width proportional to the shortage, and reduces the time width proportional to the excess if the drive is overdriven, the value of the command signal is a neutral value. If the value of the feedback is not a neutral value even after exceeding a predetermined reference time from the determination, the supply of fluid to the load is stopped, and the predetermined reference the time is,
A controller for judging a malfunction of a fluid actuator, wherein the time is a time proportional to the corrected latest basic application time.