WO2019065160A1 - Abnormality detection device - Google Patents

Abstract

The abnormality detecting device (1) of the fluid pressure actuator (A) according to the present invention includes a displacement detector (2) for detecting a displacement of the telescopic fluid pressure actuator (A), and a pump (in the fluid pressure actuator (A) P) an operation amount detector (3) that detects an operation amount of the motor (M) that drives the motor, and an abnormality detector (4) that detects an abnormality in the fluid pressure actuator (A) based on the displacement and the operation amount It is configured with.

Description

Abnormality detection device

The present invention relates to an abnormality detection device that detects an abnormality in a fluid pressure actuator.

The hydraulic actuator generally comprises a cylinder, a piston movably inserted in the cylinder, a rod inserted in the cylinder and connected to the piston, an expansion side chamber and a pressure side chamber partitioned by the piston in the cylinder And a switching valve for selectively supplying hydraulic fluid discharged by the pump to the expansion side chamber and the pressure side chamber, and a motor for driving the pump.

When driving and controlling such a hydraulic actuator, for example, as disclosed in JPH 11-171477 A, a limit switch for detecting overstretching or shrinking is provided, and extension cutting or shrinking of the hydraulic actuator is performed with the limit switch. If it detects, the method of stopping the drive of a motor is taken.

Although there is no problem in operation with the conventional hydraulic actuator, sticking occurs such that the piston can not move relative to the cylinder by, for example, catching a contaminant in the hydraulic oil between the cylinder and the piston. There was no way to detect this as an abnormality.

Then, this invention aims at provision of the abnormality detection apparatus of the fluid pressure actuator which can detect abnormality of a fluid pressure actuator.

The abnormality detection device according to the present invention includes a displacement detector that detects a displacement of an expandable and contractible fluid pressure actuator, an operation amount detector that detects an operation amount of a motor that drives a pump in the fluid pressure actuator, a displacement and an operation amount And an abnormality detector for detecting an abnormality in the fluid pressure actuator. In the abnormality detection device configured as described above, the abnormality of the fluid pressure actuator can be detected.

FIG. 1 is a diagram showing an abnormality detection apparatus according to an embodiment. FIG. 2 is a diagram showing an abnormality detection device in a first modified example of the embodiment. FIG. 3 is a diagram showing an abnormality detection device according to a second modification of the embodiment. FIG. 4 is a diagram showing the relationship between the number of rotations of the motor and the driving time when expanding and contracting the fluid pressure actuator. FIG. 5 is a diagram showing an abnormality detection device according to a third modification of the embodiment.

Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIG. 1, the abnormality detection device 1 according to the present embodiment operates the displacement detector 2 that detects the displacement of the expandable fluid pressure actuator A, and the operation of the motor M that drives the pump P in the fluid pressure actuator A. The apparatus comprises an operation amount detector 3 for detecting an amount and an abnormality detector 4 for detecting an abnormality of the fluid pressure actuator A.

The fluid pressure actuator A to which the abnormality detection device 1 is applied is, in this example, a hydraulic actuator, and is a telescopic expandable body E, a pump P driven by a motor M, and a tank for storing hydraulic oil. T, a switching valve V, and a controller C that controls the motor M and the switching valve V are provided. The working fluid in the fluid pressure actuator A may be a fluid other than the working oil, and may be a gas or a liquid other than the working oil.

The expandable body E has a cylinder 10, a piston 11 movably inserted into the cylinder 10 to divide the inside of the cylinder 10 into an expansion side chamber R1 and a pressure side chamber R2, and one end is inserted into the cylinder 10 It is equipped with a rod 12 to be connected, and operated telescopically.

When driven by the motor M, the pump P sucks in hydraulic oil from the tank T connected to the suction port and discharges pressure oil from the discharge port. The motor M is a synchronous motor in this example, and is driven by a controller C that controls the current supplied from the power source B to the motor M.

The switching valve V is a three-position four-port switching valve, and connects the discharge port of the pump P to the expansion chamber R1 and connects the tank T to the pressure chamber R2, and the discharge port of the pump P And the pressure side supply position for connecting the tank T to the expansion side chamber R1 and the interruption position for interrupting all the communication between the discharge port of the pump P, the tank T, the expansion side chamber R1 and the pressure side chamber R2. There is. The switching valve V is switch-controlled by the controller C.

Therefore, when the switching valve V is set to the expansion side supply position while driving the pump P by the motor M, pressure oil is supplied to the expansion side chamber R1 and the pressure side chamber R2 is communicated with the tank T, so the expandable body E contracts That is, the hydraulic actuator A is contracted. On the other hand, when the switching valve V is set to the pressure side supply position while the pump P is driven by the motor M, pressure oil is supplied to the pressure side chamber R2 and the expansion side chamber R1 is communicated with the tank T. Extends, that is, the fluid pressure actuator A extends. Furthermore, when the switching valve V takes the blocking position, both the expansion side chamber R1 and the compression side chamber R2 of the expandable body E are closed, and the expansion and contraction of the expandable body E is restricted. In addition, when the discharge pressure becomes excessive while driving the pump P by the motor M, the relief valve RV provided between the discharge port of the pump P and the tank T is opened, and the system of the fluid pressure actuator A can be protected. .

The displacement detector 2 is, in this example, limit switches 21 and 22 installed at both ends of the cylinder 10 of the expandable body E, and outputs an on signal to the controller C and the abnormality detector 4 when the piston 11 abuts If the piston 11 does not contact the piston 11, the on signal is not output. The limit switches 21 and 22 may be noncontact switches. When the piston 11 is displaced to the left end of the cylinder 10, one limit switch 21 abuts on the piston 11, detects the displacement of the fluid pressure actuator A to the most extended position, and outputs an ON signal. When the piston 11 is displaced to the right end of the cylinder 10, the other limit switch 22 abuts on the piston 11, detects the displacement of the fluid pressure actuator A to the most contracted position, and outputs an ON signal. That is, the displacement detector 2 of this example detects the most extended position and the most contracted position among the displacements of the fluid pressure actuator A.

The controller C of this example controls the motor M and the switching valve V, and drives the fluid pressure actuator A so as to extend and contract the most. When the controller C extends the fluid pressure actuator A according to an external command, the controller C switches the switching valve V to the pressure side supply position, and drives the motor M until the limit switch 21 outputs the on signal. The pressure actuator A is operated to extend. In this state, when the on signal of the limit switch 21 is received, the controller C stops the motor M to set the switching valve V as the blocking position to stop the extension operation of the fluid pressure actuator A. Therefore, when the controller C receives a command to extend the fluid pressure actuator A from the outside, the controller C stretches the fluid pressure actuator A, stops operation when the fluid pressure actuator A is displaced to the maximum extension position, and maintains that state. .

Conversely, when contracting the fluid pressure actuator A according to an external command, the controller C switches the switching valve V to the expansion side supply position, and drives the motor M until the limit switch 22 outputs an on signal. Thus, the fluid pressure actuator A is contracted. In this state, when the on signal of the limit switch 22 is received, the controller C stops the motor M to set the switching valve V as the blocking position to stop the contraction operation of the fluid pressure actuator A. Therefore, when the controller C receives a command for contracting the fluid pressure actuator A from the outside, the controller C causes the fluid pressure actuator A to contract, and when the fluid pressure actuator A is displaced to the retracted position, the operation is stopped and maintained in that state. .

In this example, the motion amount detector 3 detects the amount of rotation of the motor M when the controller C drives the motor M to extend or contract the fluid pressure actuator A from the stop state. That is, when the movement amount detector 3 is driven to extend or contract the fluid pressure actuator A, it counts how many times the motor M has rotated, and how many times the motor M has rotated so far The rotation amount, which is the amount indicated, is output to the abnormality detector 4. Specifically, although not shown, the operation amount detector 3 in this example includes a sensor such as a resolver or the like that can detect the rotation of the motor M and a counter that counts the number of rotations of the motor M. Output to the abnormality detector 4.

In the abnormality detector 4, when the rotation amount of the motor M received from the operation amount detector 3 is equal to or more than the threshold and there is no input of the ON signal from the limit switches 21 and 22, the fluid pressure actuator A can not expand and contract. It judges that it is a state and detects abnormality of fluid pressure actuator A. When the abnormality detector 4 detects an abnormality in the fluid pressure actuator A, the abnormality detector 4 outputs an abnormality signal to the controller C, and when the controller C receives the abnormality signal, the motor M is stopped to set the switching valve V as a shutoff position. Stop driving.

When displacing the fluid pressure actuator A from the most contracted position to the most extended position or from the most extended position to the most contracted position, the pump P to the cylinder are obtained from the inner diameter of the cylinder 10 and the displacement required for the fluid pressure actuator A. The total flow rate of hydraulic oil to be supplied into 10 is known in advance. Assuming that the rotation amount by which the motor M must rotate when displacing the fluid pressure actuator A from the most contracted position to the most extended position or from the most extended position to the most contracted position is the required amount of rotation, It is obtained from the total flow rate and the efficiency of the pump P. Since the efficiency of the pump P is known, if the total flow rate is known, the required amount of rotation of the motor M can be obtained in advance.

Therefore, when expanding or contracting the fluid pressure actuator A, the fluid does not output an ON signal from either of the limit switches 21 and 22 even though the detected rotation amount of the motor M exceeds the required rotation amount. It can be seen that the pressure actuator A is fixed and can not be displaced. That is, in the abnormality detector 4, the amount of rotation (the amount of movement) of the motor M is equal to or greater than the threshold value, and the fluid pressure actuator A is not displaced to a position corresponding to the amount of rotation (the amount of movement) It is determined that the pressure actuator A is abnormal.

Therefore, the threshold value may be set to the required rotation amount, but the pressure fluctuation may cause the relief valve RV to open and the total flow rate discharged by the pump P may not contribute to the expansion and contraction of the fluid pressure actuator A. The threshold value may be set to a value obtained by adding an addition value for preventing false detection to the required rotation amount. The addition value may be determined to be suitable for the actual fluid pressure actuator A.

The expandable body E in the fluid pressure actuator A of this example is set to a so-called single rod type, and since the total flow rate described above differs between the extension operation and the contraction operation, the extension operation is performed. The required amount of rotation differs depending on when the contraction operation is performed. Therefore, the threshold may be set to different values for determining whether or not the fluid pressure actuator A is extended and contracted when the total flow rate is different. In the case where the expandable body E is set to both rod types in which the rod 12 is also inserted into the compression side chamber R2, since the total flow rate in the case of extending the fluid pressure actuator A is equal to the total flow rate in the case of performing the contraction operation The same threshold value may be used for the extension operation and the contraction operation.

In addition, when the oil temperature of the hydraulic oil changes, the viscosity of the hydraulic oil changes, and the efficiency of the pump P changes. In general, when the viscosity of the hydraulic oil is high to a certain extent, the efficiency of the pump P tends to be low. Therefore, if the relationship between the temperature of the working fluid used for the fluid pressure actuator A and the efficiency of the pump P is grasped beforehand and the temperature of the working fluid is detected, the value of the required number of revolutions can be obtained. Since the threshold is a value determined according to the required rotation speed, if the threshold is changed according to the temperature of the working fluid, an abnormality in the fluid pressure actuator A can be detected accurately even if the temperature of the working fluid changes.

Therefore, as shown in FIG. 2, a temperature sensor 5 for detecting the temperature of the hydraulic fluid is provided, and the relationship between the temperature of the hydraulic fluid detected by the temperature sensor 5 and the threshold is mapped or functioned in advance. For example, the abnormality detector 4 can obtain the threshold value suitable for the temperature of the hydraulic oil. Therefore, in the abnormality detection device 1 shown in FIG. 2, the threshold value suitable for the temperature of the working fluid is determined, and the presence of the on signal from the limit switches 21 and 22 is monitored, and the determined threshold value and the rotation amount of the motor M By comparing the above, even if the temperature of the working fluid changes, the abnormality of the fluid pressure actuator A can be accurately detected. The temperature sensor 5 may detect the temperature in the cylinder 10, or may detect the temperature in the tank T or the pipe line forming the hydraulic circuit.

In addition, it is known that the pump P becomes less efficient due to aged deterioration. From this, the relationship between the integrated use time of the pump P or the total rotation amount of the pump P and the decrease in efficiency is grasped in advance, and the value of the required rotational speed is determined by monitoring the integrated use time or the total rotation amount. obtain. Since the threshold is a value determined according to the required number of revolutions, if the threshold is increased according to the cumulative use time or total amount of rotation of the pump P, even if the pump P loses its efficiency due to age deterioration, it is accurately An abnormality of the fluid pressure actuator A can be detected.

For example, as shown in FIG. 3, a counter 6 for counting the drive time of the motor M is provided, and the accumulated drive time of the pump P is input to the abnormality detector 4 and integrated by the abnormality detector 4. Just do it. When the total amount of rotation of the pump P is used, the amount of rotation detected by the operation amount detector 3 of this embodiment may be integrated by the abnormality detector 4. Then, if the relationship between the cumulative use time of the pump P or the total rotation amount of the pump P and the threshold is mapped or functioned in advance, the cumulative use time of the pump P or the pump P From the total amount of rotation, a threshold value suitable for the deterioration state of the pump P can be obtained. Therefore, when the threshold value is determined according to the cumulative use time of the pump P or the total rotation amount of the pump P as described above, the abnormality detection device 1 accurately corrects the abnormality of the fluid pressure actuator A even if the pump P degrades over time. Can be detected.

In this example, although the abnormality of the fluid pressure actuator A is detected based on the amount of rotation of the motor M, the abnormality of the fluid pressure actuator A is detected based on the drive time of the motor M instead of the amount of rotation of the motor M. It may be detected. That is, an abnormality may be detected by using the operation amount as the driving time of the motor M. In this case, the operation amount detector 3 may be a counter that counts the drive time of the motor M.

In this example, the controller C drives the motor M at a predetermined rotation speed (rotational speed) to extend or contract the fluid pressure actuator A. That is, as shown in FIG. 4, the rotation speed of the motor M rises from 0 in the stopped state to reach the predetermined rotation speed α, and is maintained at the predetermined rotation speed for a while, and decelerated to 0 in the stopped state. Become. Therefore, when all the hydraulic oil discharged from the pump P contributes to the extension or contraction of the expandable body E, the area of the hatched portion shown in FIG. 4 becomes equal to the required rotation amount. Therefore, if the drive time of the motor M is a time (necessary time) sufficient to make the rotation amount of the motor M equal to or more than the required rotation amount, the fluid pressure actuator A moves from the most contracted position to the most extended position or It is a habit that it is displaced to the most contracted position. Therefore, when using the drive time of the motor M, a threshold is set for the drive time, and the threshold is set to the required time or more, and the drive time is the threshold or more and the ON signals from the limit switches 21 and 22 If there is no input, the abnormality detector 4 may detect an abnormality in the fluid pressure actuator A.

When detecting the abnormality of the fluid pressure actuator A using the drive time of the motor M, when the voltage of the power supply B changes, the fluid pressure actuator A is moved from the most contracted position to the most extended position or The driving time of the motor M required to displace to the contracted position changes. When the voltage of the power source B decreases, the power supplied to the motor M also decreases, and the number of rotations of the motor M may not be maintained at the above-described predetermined number of rotations. Therefore, if the relationship between the voltage of the power supply B and the required time is grasped beforehand and the voltage is detected, the value of the required time can be obtained. Since the threshold is a value determined according to the required time, if the threshold is changed according to the voltage of the power supply B, the abnormality of the fluid pressure actuator A can be detected accurately even if the voltage fluctuates.

Therefore, as shown in FIG. 5, the voltage sensor 7 for monitoring the voltage of the power supply B is provided, and the relationship between the voltage of the power supply B detected by the voltage sensor 7 and the threshold is mapped or functioned in advance. For example, the threshold value suitable for the voltage of the power source B can be obtained from the voltage of the power source B in the abnormality detector 4. Therefore, in the abnormality detection device 1 shown in FIG. 5, the threshold value suitable for the voltage of the power source B is determined, and the presence of the on signal from the limit switches 21 and 22 is monitored, and the determined threshold value and the rotation amount of the motor M By comparing the above, even if the temperature of the working fluid changes, the abnormality of the fluid pressure actuator A can be accurately detected.

Further, instead of the amount of rotation of the motor M, the abnormality of the fluid pressure actuator A may be detected based on the amount of electric power supplied to the motor M from the power supply B. That is, the abnormality may be detected as the amount of operation supplied to the motor M. Assuming that the required rotation amount described above is N, the torque of the motor M is τ, and the electric energy is W, a relationship of N = W / 2πτ holds between the electric energy W of the motor M and the required rotation amount N . The torque τ of the motor M can be obtained if the current flowing through the motor M and the number of rotations (rotational speed) are monitored. The amount of electric power W can be obtained by monitoring the voltage applied to the motor M, the current flowing through the winding of the motor M, and the driving time of the motor M. Therefore, with respect to the amount of electric power W supplied to the motor M from the power supply B, the threshold value may be set such that the value of W / 2πτ is equal to or more than the necessary amount of rotation N to detect an abnormality. That is, the abnormality detector 4 may determine that the fluid pressure actuator A is abnormal when the amount of electric power W is equal to or more than the threshold and there is no input of the ON signal from the limit switches 21 and 22.

As described above, when the abnormality detector 4 detects an abnormality based on the amount of electric power W, the operation amount detector 3 detects the voltage applied to the motor M, the current flowing through the winding, the driving time, and the number of rotations. A sensor may be provided. When the controller C performs PWM drive of the motor M, the power amount W may be calculated from a command value generated in the controller C without using a sensor.

In this example, the displacement detectors 2 are limit switches 21 and 22 provided at both ends of the cylinder 10 to detect the displacement of the fluid pressure actuator A at the most extended position and the most contracted position. The displacement over the full stroke range of A may be monitored. Then, for example, when the fluid pressure actuator A is displaced from the current position to a desired position, the operation amount of the motor M is detected by the operation amount detector 3, and the operation amount of the motor M required for the displacement is The fluid pressure actuator A may be determined to be abnormal if the threshold is set to be equal to or greater than the movement amount and the displacement detected by the stroke sensor has not reached the desired position. As described above, when a stroke sensor is used as the displacement detector 2, an abnormality can be detected even when the fluid pressure actuator A is displaced from an arbitrary position to another arbitrary position.

Further, the circuit configuration of the fluid pressure actuator A is not limited to the circuit configuration of this example, and any configuration may be used as long as the pump P is driven by the driving of the motor M and the stretchable body E expands and contracts. Thus, for example, in the fluid pressure actuator A, the pump P is a bi-directional discharge type pump, and the expandable body E performs one operation of extension and contraction at normal rotation, and the pump E extends and contracts at reverse rotation May be configured to perform the other action of Furthermore, although the motor M is a synchronous motor in this example, the structure or type of the motor is not limited to the synchronous motor.

While the preferred embodiments of the present invention have been described above in detail, modifications, variations and changes are possible without departing from the scope of the claims.

This application claims the priority based on Japanese Patent Application No. 2017-187275 filed on September 28, 2017 to the Japanese Patent Office, and the entire contents of this application are incorporated herein by reference.

Claims (7)

An anomaly detection device,
A displacement detector that detects displacement of the extendable fluid pressure actuator;
An operation amount detector for detecting an operation amount of a motor driving a pump in the fluid pressure actuator;
An abnormality detection device comprising: an abnormality detector that detects an abnormality of the fluid pressure actuator based on the displacement and the movement amount. The abnormality detection device according to claim 1, wherein
The movement amount is a rotation amount of the motor,
The abnormality detector determines that the fluid pressure actuator is abnormal when the amount of movement is equal to or greater than a threshold and the fluid pressure actuator is not displaced to a position corresponding to the amount of movement of the motor. apparatus. The abnormality detection device according to claim 1, wherein
The operation amount is a drive time of the motor,
The abnormality detector determines that the fluid pressure actuator is abnormal when the amount of movement is equal to or greater than a threshold and the fluid pressure actuator is not displaced to a position corresponding to the amount of movement of the motor. apparatus. The abnormality detection device according to claim 1, wherein
The operation amount is an amount of power supplied to the motor,
The abnormality detector determines that the fluid pressure actuator is abnormal when the amount of movement of the motor is equal to or greater than a threshold and the displacement of the fluid pressure actuator is not displaced to a position corresponding to the amount of movement of the motor. Abnormality detection device to judge. The abnormality detection device according to claim 3, wherein
The abnormality detection device detects an abnormality of the fluid pressure actuator based on the displacement, the operation amount, and a voltage of a power supply that drives the motor. The abnormality detection device according to claim 1, wherein
The abnormality detection device detects an abnormality based on the displacement, the operation amount, and a temperature of a working fluid of the fluid pressure actuator. The abnormality detection device according to claim 1, wherein
The abnormality detection device detects an abnormality based on the displacement, the operation amount, and an integrated use time of the pump or a total rotation amount of the pump.

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