JPH08338403A - Automatic hydraulic control device - Google Patents

Abstract

PURPOSE: To enable applying of a continuous pressure and performing of pressure control accurate in good stability, by controlling a pressure of oil by controlling a hydraulic cylinder shaft with fine longitudinal motion. CONSTITUTION: A pressure valve 9 is opened by a control signal of a CPU7 to start introducing of a pressure of oil. A pressure rise is performed by an oil hydraulic pump 1 driven by the control signal of the CPU7, to perform the pressure rise to a preset pressure of a pressure switch 2, thereafter to end the pressure rise by a control signal output by the pressure switch 2. In stable control of the pressure of oil, in a condition that the pressure of oil is sealed, an output of a pressure sensor 6 is sampled at each fixed time by the CPU7, and after a fluctuation amount of the pressure of oil is calculated, this arithmetic result is converted into a signal of fine moving a hydraulic cylinder shaft 5. A fine moving signal output is transmitted to a motor 4, to longitudinal finely move the hydraulic cylinder shaft 5. By continuously performing this action, the pressure of oil can be stably controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic hydraulic control system.

[0002]

2. Description of the Related Art A conventional hydraulic pump or the like cannot be used as a highly accurate automatic hydraulic control device because it cannot control minute pressure. As a pressure calibrator, there is a weight type pressure reference device, but there is no continuity in the applied pressure and for automation, an automatic weight exchange mechanism and a storage mechanism for the number of weights according to the applied pressure are required. High cost and large size of the device pose a problem.

[0003]

[Problems to be Solved by the Invention]
Hydraulic pumps that deliver constant pressure cannot be used because minute pressures cannot be controlled. Also, with the weight type pressure application method found in the weight type pressure reference device, etc., although high-precision hydraulic pressure application is possible, there is no pressure continuity, and if a disturbance factor such as slow leak occurs in the hydraulic pressure application system, It becomes difficult to apply a stable hydraulic pressure.

An object of the present invention is to perform high-precision control of hydraulic pressure continuously for a long time, and since it is composed of a hydraulic cylinder and a feed mechanism of a cylinder shaft, it is possible to use a pressure application method without using a weight. A simple hydraulic control mechanism is to provide a system for controlling continuous pressure application and pressure with high accuracy and good stability.

[0005]

A feature of the present invention for achieving the above object is that a hydraulic cylinder and a hydraulic cylinder shaft to which a hydraulic reaction force is applied are constituted by a position control mechanism capable of being sufficiently driven, and after the hydraulic pressure is boosted, It is to control the cylinder volume by the fine movement of the hydraulic cylinder shaft.

Further, a hydraulic pump for high-speed boosting and a pressure switch for detecting hydraulic pressure are provided to detect and manage the boosting of the hydraulic system.

Further, a pressure sensor for measuring the pressure is provided in a temperature-controlled room controlled to a constant temperature to prevent temperature drift due to changes in the pressure medium of the pressure sensor and the outside air temperature.

[0008]

According to the highly accurate hydraulic control method, the hydraulic pump and the pressure switch are used for high-speed boosting, and the hydraulic cylinder volume control is performed by slightly moving the hydraulic cylinder shaft of the hydraulic cylinder provided in the hydraulic system after the boosting. For the setting and stable control of the applied pressure, the CPU takes in the data taken in by the pressure sensor, and the output position control signal is converted into fine forward and backward movement of the hydraulic cylinder shaft.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENT A block diagram is shown in FIG. This device is a device for automatically calibrating a pressure transmitter. The automatic calibration device is composed of a hydraulic control unit that applies hydraulic pressure to the pressure transmitter and an interface unit that measures the output of the transmitter. The pressure transmitter 8 to be calibrated is connected to the hydraulic control unit by the hydraulic pipe 3. The pressure valve 9 is opened by the control signal of the CPU 7 and the introduction of hydraulic pressure is started. The pressure is increased by the hydraulic pump 1 driven by the control signal of the CPU 7, and after the pressure is increased to the set pressure of the pressure switch 2, the pressure is completed by the control signal output by the pressure switch 2. As a method of confirming the pressurization, the CPU 7 determines the output signal of the pressure sensor 6 installed in the temperature-controlled room 10, and after confirming the pressurization, the pressure valve 9 is closed and the hydraulic pressure is sealed. The stable control of the hydraulic pressure is performed by changing the output of the pressure sensor 6 at a constant time in the hydraulically sealed state by the CP
After sampling by U7 and calculating the fluctuation amount of the hydraulic pressure, the calculation result is converted into a fine movement signal of the hydraulic cylinder shaft 5. The fine movement signal output is transmitted to the motor 4 to finely move the hydraulic cylinder shaft 5 back and forth. By performing this operation continuously, stable control of the hydraulic pressure is achieved. For the hydraulic pressure setting, the output signal of the pressure sensor 6 is sent to the CPU 7 as in the stable control.
, A difference from the target value stored in the CPU 7 is calculated and compared, the deviation amount is converted into a movement amount output of the hydraulic cylinder shaft 5, and the movement amount output is transmitted to the motor 4,
The hydraulic cylinder shaft 5 is moved back and forth.

[0010]

The present invention is a method of controlling the hydraulic pressure by controlling the fine movement of the hydraulic cylinder shaft in the front-rear direction, and has a simple structure and does not require disassembly, maintenance, inspection or cleaning. Further, since the weight type pressure applying method is not adopted, it is possible to apply a continuous hydraulic pressure without the need for highly accurate weight.

[Brief description of drawings]

FIG. 1 is a block diagram of a high precision hydraulic control device according to an embodiment of the present invention.

[Explanation of symbols]

1 ... hydraulic pump, 2 ... pressure switch, 3 ... hydraulic piping, 4
... motor, 5 ... hydraulic cylinder shaft, 6 ... pressure sensor, 7 ... CPU, 8 ... pressure transmitter, 9 ... pressure valve, 10 ...
Constant temperature chamber.

Claims (1)

[Claims] 1. A device for controlling a hydraulic pressure applied to a pressure sensor, wherein the hydraulic pressure is set to an arbitrary value, the means for raising the hydraulic pressure to a set value, and a constant temperature controlled constant temperature chamber are provided. And a means for calculating the amount of fluctuation of the hydraulic pressure by sampling the hydraulic pressure at regular time intervals, and a hydraulic control for controlling the hydraulic pressure by driving and controlling the hydraulic cylinder and the hydraulic cylinder shaft based on the calculation result. And an automatic hydraulic control device.