JP2008291865A - Cylinder driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder driving device of a simple and compact structure capable of accurately controlling the rod position even in the case wherein noload is applied to an actuator cylinder. <P>SOLUTION: This cylinder driving device includes an actuator cylinder, an oil pressure supply device for supplying and discharging operating fluid to/from one of a piston head side cylinder chamber and a rod side cylinder chamber of the actuator cylinder, an air pressure supply device for supplying/discharging air to/from the other cylinder chamber, and a control device for controlling drive of the oil pressure supply device and the air pressure supply device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cylinder driving device for driving a rod of an actuator cylinder forward and backward.

  2. Description of the Related Art Some hydraulic drive devices that drive a rod forward and backward by reciprocating a piston of an actuator cylinder in a cylinder by hydraulic control, use a constant displacement bidirectional rotary pump. Since this bidirectional rotary pump supplies hydraulic oil in both forward and reverse directions, both ports of the bidirectional rotary pump 42 are connected to the inlet / outlet port H of the cylinder chamber S1 on the piston head side of the actuator cylinder 50 as shown in FIG. The rod can be driven forward and backward by a simple hydraulic circuit consisting of a self-supply valve and a safety valve, without connecting a control valve.

  That is, the hydraulic oil in the reservoir tank 43 is supplied from one port to the head-side cylinder chamber S1 by the forward rotation of the pump 42, and the hydraulic oil in the rod-side cylinder chamber S2 is sucked from the other port of the pump 42 to the tank. By returning to 43, the piston 52 can be pushed out to drive the rod 51 forward, and the hydraulic oil is supplied from the other port to the rod-side cylinder chamber S2 by the reverse rotation of the pump 42 and the operation in the head-side cylinder chamber S1. By sucking oil from one port of the pump 42 and returning it to the tank 43, the piston 52 can be pulled back to retract the rod 51.

  If the bidirectional rotary hydraulic pump is used in this way, a hydraulic supply device can be configured as a compact unit 41 having no hydraulic piping with a simple hydraulic circuit that circulates hydraulic oil in a substantially closed system (for example, Patent Document 1). reference.).

  The bidirectional rotary hydraulic pump 42 is rotationally driven by a servo motor M. The servo motor M is driven by a control device 60 by a position detection signal of the piston 52 from the position sensor 53 and a pump from the pressure sensor 45. Feedback control is performed based on the pressure detection signal of the discharged hydraulic fluid.

  In addition, since the bidirectional rotary pump 42 is a constant capacity type in which the swash plate of the piston pump is fixed, the discharge flow rate is determined by the rotational speed of the pump. By controlling the pump rotation speed over a wide range from low speed to high speed, the pump discharge flow rate is efficiently controlled.

  Therefore, if such a constant displacement pump is used, it is very efficient compared to a case where loss such as hydraulic internal leakage is large, such as a variable displacement pump that changes the displacement of the pump at a constant high speed. A hydraulic supply system can be configured.

JP 2006-329241 A

  In the conventional hydraulic pressure supply apparatus as described above, when hydraulic fluid is fed from the pump 42 using the discharge circuit between the pump 42 and the head side cylinder chamber S1, the suction circuit is provided between the pump 42 and the rod side cylinder chamber S2. On the other hand, when hydraulic oil is sent from the pump 42 to the rod side cylinder chamber S2 using the discharge circuit between the rod side cylinder chamber S2 and the rod side cylinder chamber S2, a suction circuit is provided between the pump 42 and the head side cylinder chamber S1.

  Therefore, when performing position control such as positioning the rod at a predetermined initial position in a state where there is no load on the cylinder, the hydraulic oil to either the head side or the rod side is corrected each time position error correction is performed. It was necessary to completely reduce the discharge pressure to 0 MPa.

  However, in such error correction, since the discharge pressure is reduced to 0 MPa, it is likely to be affected by the residual air in the cylinder, so position control in units of several μm is difficult and is currently required. There was no choice but to control the position with a lower accuracy than the current one. On the other hand, in order to maintain the pressure in the circuit and ensure high-precision controllability, it is necessary to take measures to provide a sequence valve in the passage, but this complicates the circuit, There was a problem that the size of the apparatus was increased.

  Further, it is conceivable to use a spring as the return force of the cylinder rod as a simple configuration, but it is often difficult to design in consideration of the load and stroke. In addition, hydraulic control using an accumulator or the like is conceivable, but the accumulator is troublesome because it is subject to the high-pressure gas safety law.

  In view of the above problems, an object of the present invention is to provide a cylinder driving device capable of highly accurate rod position control even when there is no load on an actuator cylinder, while having a simple and compact configuration.

  In order to achieve the above object, a cylinder driving device according to a first aspect of the present invention supplies and discharges hydraulic fluid to and from an actuator cylinder and one of a piston head side cylinder chamber or a rod side cylinder chamber of the actuator cylinder. A hydraulic pressure supply device, a pneumatic pressure supply device that supplies and discharges air to the other of the cylinder chambers, and a control device that controls driving of the hydraulic pressure supply device and the pneumatic pressure supply device are provided.

  A cylinder driving device according to a second aspect of the present invention is the cylinder driving device according to the first aspect, wherein the hydraulic pressure supply device includes a reservoir tank and hydraulic oil in the tank with respect to the one cylinder chamber. A bi-directional rotary hydraulic pump that controls supply and discharge; and a servo motor that drives the hydraulic pump; and the pneumatic supply device is configured to discharge hydraulic fluid from the one cylinder chamber by the hydraulic supply device. An air tank for supplying air to the other cylinder chamber and containing air discharged from the other cylinder chamber when hydraulic oil is supplied to the one cylinder chamber by the hydraulic pressure supply device; and a pressure in the air tank. It has a pressure adjustment valve that adjusts below a predetermined upper limit pressure, and an air pump that pressurizes and supplies air to the air tank. That.

  Further, a cylinder driving device according to a third aspect of the present invention is the cylinder driving device according to the second aspect, wherein a position sensor that detects a rod position of the cylinder and a hydraulic pressure acting on one of the cylinder chambers. And a pressure sensor for detecting the pressure of the air pressure acting on the other of the cylinder chambers, and the control device controls the rotation speed of the servo motor based on detection signals from these sensors. And drive control of the air pump.

  According to the present invention, hydraulic oil is supplied to one cylinder chamber on the piston head side and one on the rod side of the actuator cylinder and the other by a simple configuration including a hydraulic pressure supply device and a pneumatic pressure supply device without using a cumbersome accumulator. Since air can be supplied to and discharged from the cylinder chamber in synchronism with each other, even when there is no load on the actuator cylinder, the load oil pressure is constantly applied to the hydraulic oil in one cylinder chamber. Therefore, there is an effect that the position control of the cylinder rod by the hydraulic control can be performed with high accuracy which has been difficult conventionally.

  A cylinder driving device according to the present invention supplies a hydraulic fluid supply and discharge to one of a piston head side cylinder chamber and a rod side cylinder chamber of an actuator cylinder, and supplies and discharges air to the other cylinder chamber. Since the air pressure supply device is provided and the control device controls the drive of the oil pressure supply device and the air pressure supply device, the hydraulic oil is supplied to and discharged from one cylinder chamber of the actuator cylinder. By controlling the other cylinder chamber so that air is supplied and discharged from the air pressure supply device, even when there is no load on the actuator cylinder, the other cylinder chamber The load pressure can be constantly applied by the air pressure.

  Therefore, according to the present invention, although it is a simple and compact configuration without using a cumbersome accumulator or the like, even if there is no load on the actuator, the hydraulic pressure is not reduced to 0 MPa, and it has been difficult in the past by several μm Highly accurate position control is possible.

  The hydraulic pressure supply device according to the present invention includes a reservoir tank, a bidirectional rotary hydraulic pump that controls supply and discharge of hydraulic oil in the tank to the one cylinder chamber, and a servo motor that drives the hydraulic pump; This is preferable because it is simple and can be easily unitized. In this case, if the bidirectional rotary hydraulic pump that is rotationally driven by the servo motor is a constant capacity type, the discharge flow rate of the hydraulic oil is determined by the rotational speed of the hydraulic pump. By controlling the pump rotation speed over a wide range from low speed to high speed, the pump discharge flow rate can be controlled efficiently.

  On the other hand, as a pneumatic supply device in the present invention, when hydraulic oil is discharged from one cylinder chamber by the hydraulic supply device, air is supplied to the other cylinder chamber, and hydraulic oil is supplied to one cylinder chamber by the hydraulic supply device. If it is configured to include an air tank that contains air that is sometimes discharged from the other cylinder chamber and an air pump that pressurizes and supplies the air to the air tank, it is simple and simple, but the supply of hydraulic oil by a hydraulic supply device is possible. In synchronization with the exhaust, air can be supplied to and discharged from the other cylinder chamber. In order to prevent rupture damage of the tank due to excessive pressurization and to ensure safety, a pressure adjusting valve for adjusting the pressure in the air tank to a predetermined upper limit pressure or less is provided.

  A position sensor for detecting a cylinder rod position; a pressure sensor for detecting a hydraulic pressure acting on one of the cylinder chambers; and a pressure sensor for detecting a pneumatic pressure acting on the other of the cylinder chambers. If this is the case, the control device electrically controls the rotational speed of the servo motor by adjusting the control command inputted in advance based on the detection signals from these sensors, thereby electrically controlling the rotational speed of the pump with high accuracy. It can be performed efficiently by feedback control.

  The discharge flow rate control by the pump rotation speed control is performed in a state where the displacement of the pump is constant, but in the case of a swash plate type piston pump, a fixed capacity provided with a fixed swash plate whose angle is fixed in advance. Although it is convenient to use a type pump, it may be used in a state where the angle of a variable displacement pump with a variable swash plate angle is constant. In this case, the hydraulic pressure supply device is not limited to use in the hydraulic drive system based on the rotational speed control, and can be widely used in other hydraulic drive systems not based on the rotational speed control.

  As one embodiment of the present invention, a cylinder including a hydraulic pressure supply device using a bi-directional rotating constant displacement hydraulic pump driven by a servo motor and an air supply device using an air tank in which air is pressurized and supplied by a compressor The drive is shown in the air-hydraulic circuit of FIG.

  The cylinder driving device according to the present embodiment mainly supplies air to the actuator cylinder 1, the hydraulic pressure supply device 20 that supplies and discharges hydraulic oil to and from the piston head side cylinder chamber S1, and the rod side cylinder chamber S2. The air pressure supply device 10 that supplies and discharges and a control device 30 that drives and controls these devices are configured.

  The hydraulic pressure supply device 20 in this embodiment includes a reservoir tank 22, a bidirectional rotary constant capacity hydraulic pump 21 that supplies and discharges hydraulic oil in the tank 22 to and from the pump port P, and rotationally drives the hydraulic pump 21. The servo motor M to be assembled is compactly assembled in the same unit. Further, in the hydraulic oil flow path from the reservoir tank 22 and the hydraulic pump 21 to the pump port P, a normal hydraulic relief valve 23 and a pressure sensor 24 for detecting the pressure of the hydraulic oil are arranged. The pump port P of the hydraulic pressure supply device 20 is connected to a first cylinder port HP communicating with the piston head side cylinder chamber S1 of the actuator cylinder 1.

  Furthermore, a tank port T that directly communicates with the reservoir tank 22 through an electromagnetic shutoff valve 25 and a filter 26 disposed in the same unit of the hydraulic pressure supply device 20 is further provided. 25 can be switched between a shut-off state and a communication state between the tank 22 side and the tank port T side by a command from the control device 30.

  The air pressure supply device 10 in this embodiment includes an air tank 11 communicated with an inlet / outlet port R of the rod side cylinder chamber S2 of the actuator cylinder 1 and an air pump A comprising a compressor that pressurizes and supplies air to the air tank 11. It is provided. The air tank 11 is adjusted by a pneumatic relief valve 12 as a pressure adjusting valve so that the pressure in the air tank 11 does not exceed a predetermined upper limit pressure. As a result, the air tank 11 avoids dangers such as breakage and rupture due to excessive pressurization.

  The forward / reverse drive of the rod 3 for moving the load of the actuator cylinder 1 in the cylinder drive device according to this embodiment having the above-described configuration is performed as follows. That is, based on a control command input in advance according to a desired movement amount with respect to a load to be driven, the control device 30 outputs a necessary rotation speed command to the servo motor M via the driver 31. The servo motor M rotates the hydraulic pump 21 in the forward direction accordingly. The hydraulic pump 21 sucks up the hydraulic oil in the reservoir tank 22 from one inlet / outlet port and discharges it from the other inlet / outlet port. The hydraulic oil discharged from the hydraulic pump 21 is introduced from the pump port P to the actuator cylinder 1 via the first cylinder port HP, and is supplied into the piston head side cylinder chamber S1 to push out the piston 2 and advance the rod 3. Let At this time, the air in the rod side cylinder chamber S2 is pushed out to the air tank 11.

On the other hand, when the servo motor M rotates the hydraulic pump 21 in the reverse direction in response to a command from the control device 30 via the driver 31, the hydraulic pump 21 sucks the hydraulic oil from the other inlet / outlet port and supplies the hydraulic oil to the reservoir tank 22. To discharge. As a result, the hydraulic oil is discharged from the piston head side cylinder chamber S2 and is returned from the first cylinder port HP to the hydraulic pump 21 via the pump port P. With this, the piston 2 is pulled back and the rod 3 moves backward. . At this time, air is drawn from the air tank 11 into the rod side cylinder chamber S2.
In the present embodiment, the position sensor 32 detects the position of the piston 2, and the control device 30 detects the detection signal from the position sensor 32 and the pressure sensor 24 that detects the pressure of the hydraulic oil discharged from the hydraulic pump 21. Based on this detection signal, a highly accurate feedback control is performed by adjusting the control command inputted in advance.

  In the present embodiment, the second cylinder port HT for connecting to the tank port T of the hydraulic pressure supply device 20 is provided in the piston head side cylinder chamber S1 of the actuator cylinder 1, and the piston is switched by switching the shutoff valve 25. The hydraulic oil in the head side cylinder chamber S1 can be directly returned to the reservoir tank 22. As a result, the hydraulic oil can be discharged directly into the tank at a high return speed, and the rod can be moved at a high speed. Further, if the return of the hydraulic oil is performed using only the flow path from the second cylinder port HT to the tank port T by the shut-off valve 25, the operation on the pump side is not necessary. Can do.

  As described above, in the present cylinder drive device, the position control of the piston 2 and the rod 3 is mainly performed by hydraulic control for supplying and discharging hydraulic oil to and from the piston head side cylinder chamber S1 by the hydraulic pressure supply device 20. However, in synchronism with this, air is supplied / discharged to / from the rod-side cylinder chamber S2 by the air pressure supply device 10, so that the piston head-side cylinder is supplied and discharged with hydraulic oil even when the actuator cylinder 1 is not loaded. Since the air pressure from the rod side cylinder chamber S2 always acts on the chamber S1, positioning error correction such as when initializing the rod 3 is also performed with high accuracy without lowering the oil pressure to 0 MPa. It is possible.

1 is an air-hydraulic circuit diagram showing an overall configuration of a cylinder driving device according to an embodiment of the present invention. It is a hydraulic circuit diagram which shows an example of the conventional actuator cylinder hydraulic drive unit.

Explanation of symbols

1, 50: Actuator cylinder 2, 52: Piston 3, 51: Rod S1: Piston head side cylinder chamber S2: Rod side cylinder chamber HP: First cylinder port HT: Second cylinder port 10: Air pressure supply device 11: Air tank 12 : Pneumatic relief valve 13: Air pressure sensor A: Air pump 20, 41: Hydraulic supply device M: Servo motor 21, 42: Bidirectional rotation constant displacement hydraulic pump 22, 43: Reservoir tank 23: Hydraulic relief valve 24, 45: Pressure sensor 25: Shut-off valve 26: Filter P: Pump port T: Tank port 30, 60: Controller 31: Driver 32: Position sensor

Claims (3)

An actuator cylinder;
A hydraulic pressure supply device for supplying and discharging hydraulic oil to / from one of the piston head side cylinder chamber and the rod side cylinder chamber of the actuator cylinder;
A pneumatic supply device for supplying and discharging air to the other of the cylinder chambers;
A cylinder driving device comprising: a hydraulic pressure supply device; and a control device that performs drive control of the pneumatic pressure supply device. The hydraulic supply device has a reservoir tank, a bidirectional rotary hydraulic pump that controls supply and discharge of hydraulic oil in the tank to the one cylinder chamber, and a servo motor that drives the hydraulic pump,
The air pressure supply device supplies air to the other cylinder chamber when the hydraulic oil is discharged from the one cylinder chamber by the hydraulic pressure supply device, and supplies hydraulic oil to the one cylinder chamber by the hydraulic pressure supply device. An air tank that contains air that is sometimes discharged from the other cylinder chamber, a pressure adjusting valve that adjusts the pressure in the air tank to a predetermined upper limit pressure or less, and an air pump that pressurizes and supplies air to the air tank The cylinder drive device according to claim 1, wherein the cylinder drive device is provided. A position sensor that detects a rod position of the cylinder, a pressure sensor that detects a hydraulic pressure acting on one of the cylinder chambers, and a pressure sensor that detects a pneumatic pressure acting on the other of the cylinder chambers,
3. The cylinder drive device according to claim 2, wherein the control device performs rotation speed control of the servo motor and drive control of the air pump based on detection signals from these sensors.

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