JP5453356B2 - Hydraulic device and control method of hydraulic device - Google Patents

Description

  The present invention relates to a hydraulic device that drives a hydraulic cylinder with hydraulic fluid from a hydraulic pump that is driven by an electric motor, and a control method for the hydraulic device.

  Conventionally, a drive device that is directly driven by a servo motor has been used. However, when a large driving force is required, a hydraulic device that supplies a hydraulic fluid from a hydraulic pump driven by a motor to the hydraulic cylinder and obtains a large driving force by the hydraulic cylinder is used. The hydraulic equipment requires hydraulic equipment such as electric motors, hydraulic pumps, hydraulic tanks, control valves, etc., so there is a problem of increasing the size of the equipment, and research and development for miniaturization is carried out Has been.

  Patent Document 1 discloses a control device and a control method for a hydraulic drive device that can increase the positioning accuracy of a piston rod of a hydraulic cylinder, whether in a no-load state or a loaded state, using a hydraulic pump. Is disclosed.

  In the control device of the hydraulic pressure drive device described in Patent Document 1, a hydraulic pressure drive device having a hydraulic pressure pump that is driven by a servomotor and a hydraulic pressure cylinder that moves a piston rod by hydraulic fluid from the hydraulic pressure pump is controlled. In addition, a position sensor for detecting the position of the piston rod, a motor drive device having at least a position control loop for controlling the servo motor, and a reference input for the motor drive device, the piston rod is set to a predetermined target position in the motor drive device. A control device for a hydraulic pressure drive device, comprising a position command generator for giving a position command for movement, and driving the servo motor to move the piston rod of the hydraulic cylinder to a predetermined position. A position command corrector is provided between the generator and the motor drive device, and the position command corrector is provided with a piston rod of the hydraulic cylinder in advance. Until the set initial target position is reached, the output of the position command generator is output as the reference input of the motor drive device, and the predetermined position correction standby necessary for the piston rod to substantially stop after reaching the initial target position After the time has elapsed, the deviation between the position command and the output of the position sensor is added to the position command, and the addition result is output as a reference input. The position command corrector The calculation operation of adding the deviation between the output of the position sensor and the position command to the position command at a predetermined sampling period until the predetermined position correction duration time elapses after the elapse of the time and the position correction standby time. The reference input value is changed repeatedly.

  In Patent Document 2, a hydraulic pump that is rotated by an electric motor capable of controlling the number of revolutions is configured as a single hydraulic pump that enables control of a low pressure and a large flow rate and a control of a high pressure and a small flow rate. A hydraulic drive device that can be made compact as a whole is disclosed.

  In the hydraulic pressure drive device described in Patent Document 2, the motor is driven by an electric motor capable of controlling the number of revolutions, a hydraulic pump that is rotated by the electric motor and discharges the pressurized liquid, and a hydraulic fluid that is discharged from the hydraulic pump. A hydraulic actuator and a control unit that controls the rotation speed of the electric motor so that the actual value fed back from the hydraulic actuator side matches the target value. The hydraulic pump has a maximum displacement with the largest displacement volume. In addition, the displacement volume can be switched to a minimum volume that is smaller than the maximum volume and greater than zero, and the displacement of the hydraulic fluid discharged to the hydraulic actuator is less than the set pressure and the displacement volume is switched to the maximum volume. The displacement volume is switched to the minimum volume when the pressure of the pressure liquid discharged to the nozzle is equal to or higher than the set pressure.

  Patent Document 3 discloses a hydraulic drive device that can be made compact by configuring a single hydraulic pump that is rotated by an electric motor that can control the number of rotations.

  In the hydraulic pressure drive device described in Patent Literature 3, the motor is driven by an electric motor capable of controlling the number of rotations, a hydraulic pump that is rotated by the electric motor and discharges the pressurized liquid, and a hydraulic fluid that is discharged from the hydraulic pump. A hydraulic actuator, and a control unit that controls the rotational speed of the electric motor so that the actual value fed back from the hydraulic actuator side matches the target value. As for the relationship with the discharge amount, constant horsepower control is performed in which the discharge amount decreases and the horsepower is controlled to be substantially constant as the discharge pressure increases.

Japanese Patent No. 4206194 JP 2005-140175 A JP 2005-308047 A

  In the control device and control method of the hydraulic drive device described in Patent Document 1, it is described that the positioning accuracy of the piston rod of the hydraulic cylinder can be increased, but loop control is frequently used, and the control system There is a problem that a delay occurs. In particular, since the position control system and the speed control system are feedback circuits (see FIG. 1 of Patent Document 1), a delay in the control system occurs.

  Similarly, in the hydraulic drive devices described in Patent Documents 2 and 3, since the motor control is performed using the servo motor feedback (reference numeral 16 in FIG. 1 of Patent Documents 2 and 3), a control delay is caused. There is a problem that occurs.

An object of the present invention is to provide a hydraulic device and a control method of the hydraulic device that can prevent a control delay.
Another object of the present invention is to provide a hydraulic device and a control method for the hydraulic device that can prevent control delay and increase positioning accuracy while improving the response of the hydraulic pump.

(1)
The hydraulic device according to the present invention includes a hydraulic pump driven by a motor and capable of rotating in both directions, a hydraulic actuator driven by a piston rod by the hydraulic pump, a control device for controlling driving of the motor, and a hydraulic actuator A displacement detector that detects the displacement of the piston rod of the motor, and the control device drives the motor without using a feedback circuit based on the differential component of the rotational fluctuation of the motor and the proportional component and integral component of the displacement detector. It is something to control.

  In this case, since the control is performed based on the proportional component and the integral component using the information from the displacement detector that detects the displacement of the piston rod of the hydraulic actuator, the control can be performed with high accuracy. That is, the positioning accuracy can be increased by detecting the displacement of the piston rod to be directly controlled. Further, since the servo motor feedback circuit is not used, the delay of the control system can be prevented. As a result, the positioning accuracy can be improved while improving the responsiveness of the hydraulic pump.

(2)
In the hydraulic device, the control device includes a controller and a servo driver. The servo driver has only an amplification function and does not have a feedback loop.

  In this case, since the servo driver has only an amplification function and does not use a feedback loop, the delay of the control system can be prevented. As a result, the positioning accuracy can be improved while improving the responsiveness of the hydraulic pump.

(3)
The hydraulic device may further include a load data detector that detects load data of the piston rod, and the control device may further control the driving of the motor including the load data of the load data detector.

  In this case, a minute displacement can be detected as load data using a load cell, a spring displacement, a displacement sensor, or the like. As a result, in the hydraulic device, even if it is a minute displacement, a large pressure change can be caused to increase the positioning accuracy of the hydraulic device.

(4)
In the hydraulic device, the motor, the hydraulic pump, and the hydraulic actuator may be a motor pump integrated cylinder.

  In this case, since the motor, the hydraulic pump, and the hydraulic actuator are motor pump integrated cylinders, the hydraulic device can be downsized.

(5)
The control method of the hydraulic device according to the second invention is a control method for controlling the hydraulic device, the first step of extracting the differential component of the rotational fluctuation of the motor that drives the hydraulic pump, and the hydraulic pump Control of the motor based on the second step of extracting the proportional component of the displacement detector that detects the displacement of the piston rod of the hydraulic actuator driven by the third step and the third step of extracting the integral component of the displacement detector To do.

  In this case, since the control is performed based on the proportional component and the integral component using the information from the displacement detector that detects the displacement of the piston rod of the hydraulic actuator, the control can be performed with high accuracy. That is, the positioning accuracy can be increased by detecting the displacement of the piston rod to be directly controlled. Further, since the servo motor feedback circuit is not used, the delay of the control system can be prevented. As a result, the positioning accuracy can be improved while improving the responsiveness of the hydraulic pump.

(6)
In the control method of the hydraulic device, the control method of the hydraulic device includes a first control step for controlling driving of the motor based on all components of the first step, the second step, and the third step, and a first control unit. And a second control step of only amplifying the control signal.

  In this case, in the second control step, only the amplification function is provided and no feedback system loop is used, so that a delay in the control system can be prevented. As a result, the positioning accuracy can be improved while improving the responsiveness of the hydraulic pump.

It is a schematic diagram which shows an example of the hydraulic apparatus concerning this Embodiment. It is a flowchart explaining the process of the controller which controls a solenoid valve. It is a schematic diagram which shows an example of the conventional hydraulic device.

  Embodiments according to the present invention will be described below with reference to the drawings. In this embodiment, a motor pump integrated cylinder in which a pump, a motor, and a hydraulic cylinder are integrated by forming a manifold into a pipe will be described.

(One embodiment)
First, FIG. 1 is a schematic diagram showing an example of a hydraulic device 100 according to the present embodiment.

(Outline of hydraulic equipment)
1 mainly includes a hydraulic cylinder 200, a linear displacement meter 250, a solenoid valve 300, a motor 400, an encoder 420, a pressure gauge 430, a pump 450, a controller 500, and a tank 600.

1 includes an amplifier 510, a B-axis input circuit 520, an A-axis input circuit 540, an arithmetic circuit 550, an output circuit 560, and an amplifier 570. The arithmetic circuit 550 includes, for example, a CPU (Central Control Device), a ROM (Read Only Memory), a RAM (Random Memory), and the like.
Note that the amplifier 510 and the amplifier 570 illustrated in FIG. 1 may be separately provided without being integrated with the controller 500.

  The hydraulic cylinder 200 is a double-acting cylinder and includes a piston 210 and a piston rod 220. A linear displacement meter 250 is attached to at least one of the piston 210 and the piston rod 220. Here, the linear displacement meter 250 includes a magnetostrictive sensor. The linear displacement meter 250 is arranged so that it can directly detect the displacement in the exit direction and the return direction of the piston rod 220 of the hydraulic cylinder 200.

  As shown in FIG. 1, the pressure data of the pressure gauge 430 is amplified by an amplifier 510, and the amplifier 510 gives the amplified pressure data to the B-axis input circuit 520. The B-axis input circuit performs a predetermined process and calculates Pressure data is supplied to the circuit (PID control) 550. The predetermined process is a process related to the load control system.

On the other hand, the encoder 420 detects the drive displacement of the motor 400 and supplies the detection data to the A-axis input circuit 540. The A-axis input circuit 540 uses the differential component of the drive displacement detection data as the differential data (D). (PID control) 550.
The linear displacement meter 250 detects the displacement of the hydraulic cylinder 200 in the outgoing direction and the return direction, and supplies the detected data to the A-axis input circuit 540. The A-axis input circuit 540 converts the proportional component of the detected data into proportional data (P ), The integral component of the detected data is given to the arithmetic circuit (PID control) 550 as integral data (I). This process is a process related to the position control system.

  The arithmetic circuit (PID control) 550 calculates pressure data, position proportional data, position integral data, and differential data of drive displacement, and provides calculation result data to the output circuit 560. The output circuit 560 converts the calculation result data into a motor control signal (torque signal) and supplies it to the amplifier 570. The amplifier 570 amplifies the motor control signal (torque signal) and gives it to the motor 400. The motor 400 is driven based on the motor control signal. The arithmetic circuit (PID control) 550 outputs an electromagnetic valve opening / closing signal to the solenoid of the electromagnetic valve 300. The electromagnetic valve 300 opens and closes the valve based on the electromagnetic valve opening / closing signal.

  Although not shown in FIG. 1, the output of the encoder 420 may be supplied to the amplifier 570 and used for excitation control of the motor 400.

(Hydraulic cylinder operation)
Hereinafter, the operation of the hydraulic cylinder 200 will be briefly described. First, the motor 400 rotates according to the motor control signal OF from the controller 500, and the pump 450 is driven according to the rotation of the motor 400. In the present embodiment, at least the pump 450 can rotate forward and backward. Furthermore, the motor 400 may be capable of forward and reverse rotation. That is, at least one or both of the pump 450 and the motor 400 may be rotatable forward and backward. A plurality of motors 400 and pumps 450 may be provided.

  The hydraulic cylinder 200 includes a rod-side port RP and a head-side port HP. When pressure oil is sent from the pump 450 to the head-side port HP via the electromagnetic valve 300, the piston rod 220 extends and the rod-side port RP Returned to pump 450. As shown in FIGS. 1 and 2, this state is referred to as the piston rod 220 of the hydraulic cylinder 200 being in the outgoing direction.

On the other hand, when the pressure oil is sent from the pump 450 to the rod side port RP via the electromagnetic valve 300, the piston rod 220 contracts and the pressure oil is returned from the head side port HP to the pump 450 and the tank 600. As shown in FIGS. 1 and 2, this state is that the piston rod 220 of the hydraulic cylinder 200 is in the return direction.
As described above, the piston rod 220 of the hydraulic cylinder 200 double-acts in the exit direction or the return direction. Further, a heavy object (not shown) is connected to the piston rod 220 of the hydraulic cylinder 200, and the piston rod 220 of the hydraulic cylinder 200 double-acts in the outward direction or the return direction in order to move the heavy object. . In this embodiment, since a difference corresponding to the volume of the piston rod 220 is generated, the difference is absorbed and controlled by controlling the supply or discharge of the oil amount from the tank 600.

(Solenoid valve control processing)
Hereinafter, a control example of the electromagnetic valve 300 shown in FIG. 1 will be described. FIG. 2 is a flowchart for explaining the processing of the controller 500 that controls the electromagnetic valve 300.

  As shown in FIG. 2, first, the rotation direction of the motor 400 is detected using the encoder 420 (step S1). Here, when the rotation direction of the motor 400 is the return direction, the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is detected by the linear displacement meter 250 (step S2).

  Here, if the detection result from the linear displacement meter 250 determines that the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is the outgoing direction, the controller 500 determines that a disturbance has occurred in the hydraulic cylinder 200, and The solenoid valve 300 is controlled to be closed (step S3). That is, although the solenoid valve 300 is controlled in the return direction, the piston rod 220 of the hydraulic cylinder 200 is moving in the reverse direction, so the solenoid valve 300 is closed and the piston rod 220 of the hydraulic cylinder 200 is closed. Suppress movement.

On the other hand, when it is determined that the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is the return direction, it is determined whether or not the speed of the piston rod 220 of the hydraulic cylinder 200 is greater than a predetermined value SA (step S4). When the speed of the piston rod 220 of the hydraulic cylinder 200 is larger than the predetermined value SA, the opening of the solenoid valve 300 on the head side of the solenoid valve 300 is controlled (step S5).
Thereby, part of the oil amount is returned from the head side to the tank 600 side via the electromagnetic valve 300 on the head side. Therefore, since the amount of oil returned from the head side to the pump 450 is reduced, the amount of oil sent from the pump 450 to the rod side can be reduced.

  On the other hand, when the speed of the piston rod 220 of the hydraulic cylinder 200 is smaller than the predetermined value SA, the rod-side and head-side solenoid valves 300 of the solenoid valve 300 are closed (step S3). Thereby, all of the oil amount flows from the head side port HP to the pump 450, and the oil amount sent from the pump 450 flows to the rod side port RP, so that the speed of the hydraulic cylinder 200 can be increased.

  On the other hand, in the process of step S1, when the encoder 420 determines that the rotation direction of the motor 400 is the outgoing direction, the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is detected by the linear displacement meter 250 (step S12).

  Here, if the detection result from the linear displacement meter 250 determines that the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is the return direction, the controller 500 determines that a disturbance has occurred in the hydraulic cylinder 200, and The solenoid valve 300 is controlled to be closed (step S3).

On the other hand, when it is determined that the traveling direction of the piston rod 220 of the hydraulic cylinder 200 is the outgoing direction, it is determined whether or not the speed of the piston rod 220 of the hydraulic cylinder 200 is equal to or less than a predetermined value SB (step S14). When the speed of the piston rod 220 of the hydraulic cylinder 200 is equal to or less than the predetermined value SB, the solenoid valve 300 related to the pipe on the rod side is controlled to open (step S15). As a result, the amount of oil can be supplied from the tank 600 to the head side from the tank 600 via the electromagnetic valve 300, and the speed of the piston rod 220 of the hydraulic cylinder 200 can be adjusted to the predetermined value SB.
On the other hand, when the speed of the piston rod 220 of the hydraulic cylinder 200 is greater than the predetermined value SB, the rod side and head side solenoid valves 300 of the solenoid valve 300 are closed (step S3).

  As described above, in the hydraulic device 100, since the pressure suddenly changes due to the minute displacement of the piston rod 220 of the hydraulic cylinder 200, a control system capable of high-speed response is required. Furthermore, since the movement of the piston rod 220 is nonlinear due to the problem of hunting or dead zone, the linear displacement meter 250 can be used for reliable detection.

  Next, FIG. 3 is a schematic diagram showing an example of a conventional hydraulic apparatus having a servo motor feedback circuit.

  As shown in FIG. 3, the conventional hydraulic device 900 moves a heavy object 900 W, and the hydraulic device 900 feeds a servo motor system feedback in order to drive a hydraulic pump 901 and a double-acting cylinder 903. It has a circuit.

  The servo motor system feedback circuit includes a hydraulic pump 901, a servo motor 902, a double acting cylinder 903, a rotation speed detection sensor 914, a servo motor driver 916, a pressure detection sensor 917, a controller 919, and a position detection sensor 920.

  In the servo motor system feedback circuit shown in FIG. 3, a rotational speed detection sensor 914 such as a rotary encoder detects the rotational speed of the servo motor 902, and the detected actual rotational speed of the servo motor 902 is fed back to the servo motor driver 916 by feedback wiring. give feedback.

  The pressure detection sensor 917 is disposed in the first flow path 905, detects the pressure of the pressure liquid supplied to the head side port of the double acting cylinder 903, and feeds back the detected actual pressure value to the controller 919 via the feedback wiring. .

  The position detection sensor 920 detects the position of the piston rod of the double-acting cylinder 903. Here, a linear scale that outputs a pulse corresponding to the displacement of the position is used, and the actual value of the detected position is fed back to the controller 919 through a feedback wiring. .

  The controller 919 outputs a position command (instructing the number of revolutions) to the servo motor driver 916 so that the actual value of the position fed back from the feedback wiring matches the target value of the position input as an operation command, and feedback from the feedback wiring. A pressure command (commanding the number of revolutions) is output to the servo motor driver 916 so that the actual pressure value coincides with the target pressure value input as the operation command.

  The servo motor driver 916 controls the rotation speed of the servo motor 902 so that the rotation speed of the servo motor 902 fed back from the feedback wiring matches the position command or pressure command input from the controller 919. The servo motor driver 916 and the controller 919 constitute a control unit.

As shown in FIG. 3 above, in the hydraulic device 900 having the loop circuit of the position component of the servo motor driver, the hydraulic device having the loop circuit of the servo motor system feedback circuit, or the like, there is a delay in the control system. Arise. That is, a time delay occurs due to the servo motor feedback circuit.
Even if control is performed to minimize the time delay, the servo motor does not follow.

  However, in the hydraulic apparatus 100 according to the present embodiment, since the amplifier 570 has a function of amplifying only the motor control signal (torque signal) in the controller 500, a conventionally used servo motor feedback circuit (position) And a speed signal) are not formed, and the delay of the control system can be prevented.

  Further, in the hydraulic device 100, since the pressure is suddenly changed by a minute displacement of the piston rod 220 of the hydraulic cylinder 200, a control system capable of high-speed response is required. Furthermore, even if the movement of the piston rod 220 is non-linear due to the problem of hunting or dead zone, the accuracy of direct position detection by the linear displacement meter 250 can be improved.

  In the present embodiment described above, since the proportional component and the integral component obtained from the linear displacement meter 250 that detects the cylinder displacement of the hydraulic cylinder 200 are used, it is possible to perform control with high accuracy. That is, the positioning accuracy can be remarkably improved by detecting the displacement of the piston rod 220 to be directly controlled. Furthermore, since control is performed using the differential component from the pressure gauge 430, it is possible to cope with sudden fluctuations.

  Further, as described above, since the servo motor feedback circuit is not used, the delay of the control system can be prevented. As a result, in the hydraulic device 100, positioning accuracy can be improved while improving the responsiveness of the hydraulic cylinder 200.

  In the present invention, the motor 400 corresponds to the motor, the pump 450 corresponds to the hydraulic pump, the hydraulic cylinder 200 corresponds to the hydraulic actuator and the motor pump integrated cylinder, the controller 500 is the control device, and the first control step. At least the arithmetic circuit 550 corresponds to the controller, the amplifier 570 corresponds to the servo driver, the second control step, the hydraulic device 100 corresponds to the hydraulic device, the electromagnetic valve 300 corresponds to the electromagnetic valve, The linear displacement meter 250 corresponds to a displacement detector, a displacement sensor, and a magnetostrictive sensor, the differential data (D) corresponds to the first step, the proportional data (P) corresponds to the second step, and the integral data (I ) Corresponds to the third step.

  A preferred embodiment of the present invention is as described above, but the present invention is not limited thereto. It will be understood that various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, although the effect | action and effect by the structure of this invention are described, these effect | actions and effects are examples and do not limit this invention.

DESCRIPTION OF SYMBOLS 100 Hydraulic apparatus 200 Hydraulic cylinder 250 Linear displacement meter 300 Solenoid valve 400 Motor 450 Pump

Claims (6)

A hydraulic pump driven by a motor;
A hydraulic actuator driven by a piston rod by the hydraulic pump;
A control device for controlling the driving of the motor;
A displacement detector for detecting a displacement of a piston rod of the hydraulic actuator,
The control device includes:
A hydraulic apparatus for controlling driving of the motor based on a differential component of rotation fluctuation of the motor and a proportional component and an integral component of the displacement detector. The control device comprises a controller and a servo driver,
2. The hydraulic apparatus according to claim 1, wherein the servo driver has only an amplification function and does not have a feedback loop. A load data detector that detects load data of the piston rod;
The hydraulic device according to claim 1, wherein the control device further controls driving of the motor by further including load data of the load data detector.   4. The hydraulic apparatus according to claim 1, wherein the motor, the hydraulic pump, and the hydraulic actuator are motor pump integrated cylinders. 5. A control method for controlling a hydraulic device, comprising:
A first step of extracting a differential component of rotational fluctuations of the motor that drives the hydraulic pump;
A second step of extracting a proportional component of a displacement detector for detecting a piston rod displacement of a hydraulic actuator driven by the hydraulic pump;
And a third step of extracting an integral component of the displacement detector, and a control method of the hydraulic device for controlling the driving of the motor based on the third step. The control method of the hydraulic device is:
A first control step for controlling driving of the motor based on all components of the first step, the second step, and the third step;
The hydraulic device control method according to claim 5, further comprising a second control step of only amplifying a control signal from the first control unit.