JPS59197602A - Driving unit for hydraulic actuator - Google Patents

Abstract

PURPOSE:To eliminate a trouble caused by the contamination of fluid, by engaging a feed screw with the piston of a cylinder, having two operating fluid pressure chambers, and driving the feed screw by an air motor controlled through a position sensor signal of a hydraulic actuator. CONSTITUTION:A feed screw 6 is engaged with a piston 5, having two operating fluid pressure chambers 8, 9, in a cylinder 2. Then an air motor 1, being connected to the feed screw 6, is driven and controlled by a position sensor signal of a hydraulic actuator. In this way, fluid in each operating fluid pressure chamber 8, 9 of the cylinder 2 is allowed to independently flow only shuttling between said chamber and the hydraulic actuator respectively without causing any necessity for interposing a valve or the like in the half way, thus hardly causing any trouble due to the contamination of the fluid and generation of heat due to the friction of a flow of the fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive unit for a hydraulic actuator used to linearly move an operating part of, for example, an industrial robot or a transfer feeder.

Conventionally, this type of hydraulic actuator has been driven and its position controlled using a combination of a hydraulic pump unit and a hydraulic servo valve. However, with this structure, there is a large loss of hydraulic energy, and it is necessary to pay close attention to the cleanliness of the oil and change the oil frequently, and in such cases, the handling of the oil must be left to professionals. . Hydraulic pump units require water cooling during use and are prone to failure.
It is expensive and its maintenance is very troublesome. There is also a motion generator using a cam as a drive device for a hydraulic actuator, but this is a fixed stroke type and cannot control the position. In addition, this cam type generator is large and has space problems, has a complicated structure, and is subject to a large impact when stopped.

The present invention solves these conventional defects and problems, and can simultaneously perform the functions of a hydraulic pump unit and a hydraulic servo valve, has good operational performance such as high-speed operation, acceleration and deceleration, and is structurally integrated. The object of the present invention is to provide a drive unit for a hydraulic actuator.

The drive unit according to the present invention includes a cylinder device including two operating fluid chambers each independently communicating with a hydraulic actuator, and a feed screw installed in the cylinder device and screwed into engagement with a piston of the cylinder device. The air motor includes an air motor having an output shaft as an output shaft, and a control device that controls the air motor based on a position sensor signal of the hydraulic actuator.

The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 is a longitudinal sectional view of a drive unit 10 according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a hydraulic actuator to which the drive unit of the present invention is connected.

The drive unit 1o includes a cylinder device and an air motor control device, which will be described later. In the cylinder device, a hollow piston 5 is housed in a cylinder 2 having two ports 3 and 4, and an air motor 1 is attached to one end of the cylinder 2. The output shaft of the air motor 1 has a feed screw 6.
are connected to each other, and the feed screw 6 is screwed to the piston 5 via a nut 7. Between the cylinder 2 and the piston 5, hydraulic pressure chambers 8, 9 for actuating the actuators are formed which are connected to the respective ports 3.4. Air vent holes 17 are provided in the end covers at both ends of the cylinder 2.

The control device for the air motor 1 includes an air supply source 18 and an air motor l.
a pair of solenoid valves 11.14 for switching between
A pair of solenoid valves 12, 15, . . . which connect and shut off the working air of the air motor l and outside air via the solenoid valves 11, 14. ! : and a pair of flow rate control valves 13 and 16.

As shown in FIG. 2, the ports 3 and 4 of the cylinder device of the drive unit 10 are independently connected to the hydraulic actuator 2.
It is connected to each chamber 31.3'2 of the cylinder 23 of o. The hydraulic actuator 2o has a position sensor 25 such as a direct-acting potentiometer or a linear encoder, and the sensor 25 detects a load 40 (robot , manipulator, transfer feed device.

It is designed to detect the linear movement position or movement amount of a machine tool's feed table, etc.). In Fig. 2, reference numerals 26 and 27 are relief valves installed in the hydraulic piping connecting the drive unit 10 and the hydraulic actuator 20, and 30 is a pneumatic hydraulic pressure valve for replenishing leaked working fluid into the system. Converter, 28.29 is its check valve.

With such a configuration, the piston 2 of the hydraulic actuator 20
2 in one direction (for example, the direction of the solid arrow in FIG. 2) and its position control, the air motor control device's treid valve 11 is turned on and the solenoid valve 14 is turned off.
Turn off solenoid valves 12 and 15. As a result, the compressed air from the air supply source 18 causes the air motor 1 to rotate in the normal direction, and the piston 5 of the drive unit 10 moves in the direction of the solid line arrow by the feed screw 6 of the output shaft and the nut 7 fixed to the piston 5. The liquid in the actuating hydraulic pressure chamber 8 is applied to the actuator 2.
Hydraulic actuator 2
0 piston 22 moves in the direction of the solid arrow, and the liquid in the cylinder chamber 32 is returned to the operating hydraulic pressure chamber 9. piston 2
The predetermined movement position of 2 is detected by the position sensor 25,
This signal turns on the solenoid valve 15, and the air on the exhaust side of the air motor 1 is discharged to the atmosphere through the flow rate control valve 16, and the control valve 16 applies a brake to the air motor 1. Further, when the piston 22 reaches the home position, the solenoid valve 14 is turned on, and the air on the forward rotation side and the reverse rotation side is balanced at high pressure, and the air motor 1 is stopped. To move the piston 22 in the opposite direction (in the direction of the dotted arrow), the solenoid valves 11, 12.15 are turned off and the solenoid valve 14 is turned on, contrary to the above. The solenoid valve 12 is turned on by the signal from the position sensor 25, the brake is applied by the control valve 13, and the solenoid valve 11 is further turned on and stopped.

Since the drive unit of the present invention is composed of a single component that combines a cylinder device and an air motor, the structure is simple and maintenance is easy. Since the working fluid in each chamber of the cylinder device only moves back and forth between the actuator and the actuator independently without passing through any valves or the like, troubles due to fluid contamination and heat generation due to friction of the fluid flow rarely occur. do not have. Moreover, since the required amount of liquid only needs to be flowed when required, energy and resource conservation can be achieved. Air motors have large starting torque and braking torque, and the system has extremely good acceleration and deceleration performance, making them suitable for high-speed operation. When controlling the position, the flow control valve of the air motor can be used to apply a brake to stop the air motor, which has many advantages, such as extremely smooth operation.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a drive unit for a hydraulic actuator according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a hydraulic actuator to which the drive unit of the present invention is connected. 1...Air motor, 2...Cylinder, 5...
- Piston, 6... Feed screw, 7... Nut, 8.9... Hydraulic pressure chamber for operation, 10... Drive unit, 11.12, 14.15... Renoid valve, 13.
16...Flow rate control valve, 18...Air supply source, 20...
...Hydraulic actuator, multi-agent patent attorney Rikichi Somekawa

Claims (1)

[Claims] a cylinder device including two operating hydraulic chambers each independently communicating with a hydraulic actuator; and an air motor having an output shaft equipped with a feed screw that is attached to the cylinder device and threadably engages with a piston of the cylinder device. , and a control device for controlling the air motor based on a position sensor signal of the hydraulic actuator.