JPH0219603Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a binary control system for pressure in a hydraulic circuit.

Conventionally, the pressure in a hydraulic circuit is generally controlled by a relief valve or other pressure control valve, but with this type of valve, it is difficult to digitally control the pressure in multiple stages by instructions from a computer, for example.
This had the disadvantage that control equipment had to be controlled using a servo valve or the like equipped with an amplifier, making the control equipment expensive.

The purpose of the present invention is to solve such drawbacks, and the hydraulic circuit 1 is provided with a branch passage 3 connected to the tank 2, and the branch passage 3 is provided with a first position 4 for opening the branch passage 3 and a branch passage 3 connected to the tank 2. A pressure control device comprising a solenoid valve 7 that can freely switch the branch passage 3 to a second position 6 where the branch passage 3 once bypasses the bypass passage 5 and communicates with the branch passage 3 again, and a relief valve 8 provided in the bypass passage 5. It is characterized by providing a plurality of sets of 9. Each solenoid valve 7 of each pressure control device 9 is normally located at the first position 4 which opens the branch passage 3, but when the solenoid is energized by an instruction from a computer or the like, it moves to the second position 6. Switch to .

The relief valve 8 of the bypass path 5 of each pressure control device 9 is, for example, a general balance piston type relief valve. When four sets of pressure control devices 9 are provided in the branch path 3 as shown in the figure, each set of pressure control devices 9 is The relief valve 8 is, for example, 10Kg/cm ² , 20Kg/cm ² , 40Kg/cm ² and
Set to operate with a differential pressure of 80Kg/cm ² .
By selectively energizing the solenoid, the maximum pressure of the hydraulic circuit 1 is controlled as follows.
That is, when the solenoids of all the solenoid valves 7 are demagnetized, each valve 7 exists in the first position 4 and communicates with the branch passage 3 or directly with the tank 2, so that the hydraulic circuit 1
pressure becomes almost 0, and when only the solenoid valve 7a is energized to move to the second position 6, the branch passage 3 is connected to the tank 2 via the relief valve 8a of the bypass passage 5, so that the hydraulic circuit 1 The pressure is controlled to 10 kg/cm ² which is the set pressure of the relief valve 8a. When each of the solenoid valves 7b, 7c, 7d is independently operated to the second position 6, each relief valve 8b, 8
c, 8d setting pressure, i.e. 20Kg/cm ² , 40Kg/cm ² , 80
The pressure in the hydraulic circuit 1 is controlled to Kg/cm ² . Furthermore, when the solenoid valves 7a and 7b are operated simultaneously, the pressure in the hydraulic circuit 1 is controlled to 30 kg/cm ² which is the sum of the set pressures of the relief valves 8a and 8b.
By arbitrarily selecting and operating in a binary manner, the pressure in hydraulic circuit 1 can be adjusted from 0 to 150Kg/ ^cm2 by 10Kg/cm2 ^.
Can be controlled in increments. This is used as each relief valve 8, and a commercially available relief valve is used which opens when the force of the fluid pressure acting on the inlet exceeds the force of the spring by pressing a spring-loaded poppet against the inlet. To further explain this case, a force equal to the product of the primary pressure of the inlet and the area of the inlet acts on the front of the poppet, and a force equal to the product of the area of the inlet and the secondary pressure of the outlet acts on the back of the poppet. A force is applied, and the differential pressure between the primary pressure and the secondary pressure can be controlled to a set value obtained by dividing the spring force by the inlet area. Therefore, when the relief valves 8a to 8d are connected in series as shown, the primary pressure of the relief valve 8d is a pressure _P1 equal to the pressure of the hydraulic circuit 1, and its secondary pressure _P2 is _P1.
The primary pressure of the next valve 8c becomes this pressure _P2 , and each time it passes through each valve, it drops by the set pressure of each valve, and the final secondary pressure of the valve 8a becomes the tank pressure P. ₀ , and the pressure _P1 in the circuit 1 is controlled to the sum of the set pressures of each valve. If the circuit pressure is less than the sum of the set pressures of each relief valve, the relief valve will not open and the circuit pressure will be maintained.

In this way, a plurality of sets of pressure control devices 9 each consisting of a solenoid valve 7 and a relief valve 8 are provided in the branch path 3 of the hydraulic circuit 1 of the device of the present invention.
The pressure in the hydraulic circuit 1 is digitally controlled by selectively operating the solenoid valve 7 and the relief valve 8. Commercial products can be used as they are for the solenoid valve 7 and the relief valve 8, and they can be manufactured at low cost.

[Brief explanation of drawings]

The drawing is a diagram showing an embodiment of the device according to the invention. 1...Hydraulic circuit, 2...Tank, 3...Diversion path, 4...First position, 5...Bypass path, 6...
Second position, 7... Solenoid valve, 8... Relief valve, 9... Pressure control device.

Claims (1)

[Scope of utility model registration request] A branch path 3 connected to the tank 2 is provided in the hydraulic circuit 1, and a first position 4 is provided at which the branch path 3 is opened, and the branch path 3 is connected to the branch path 3 once bypassing the bypass path 5 and connected to the branch path 3 again. A binary pressure control system characterized in that a plurality of sets of pressure control devices 9 each consisting of a solenoid valve 7 which can be freely switched to a second position 6 in communication with the bypass passage 5 and a relief valve 8 provided in the bypass path 5 are provided in series. Device.