JPH01216104A - Flow/pressure control valve - Google Patents

Abstract

PURPOSE:To control both flow rate and pressure with a single control valve by a method wherein pressure functioning to the end of a main spool is transformed into load pressure and tank pressure. CONSTITUTION:Constant-head springs 3 are provided at both ends of a main spool 2, an electricity-oil converting member 1 is provided on one end of the main spool 2, and at the other end of the main spool 2, a switching device 5 which transforms pressure functioning to this end into load pressure and tank pressure is connected. By applying tank pressure to the second end of the main spool 2, flow rate can be controlled, and by applying load pressure, pressure can be controlled. Both flow rate and pressure can thus be controlled by a single control valve.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) Hydraulic actuators are often required to control both speed (rotational speed) and driving force (torque).

The present invention relates to a control valve that has the function of controlling the flow rate and pressure applied to an actuator in one unit in order to realize the above control function.

(Prior art) Flow rate control valves must control the opening of the main valve to a constant level in response to the input, whereas control valves must control the opening depending on the deviation between the input and the current load pressure. Mechanically integrating the two is difficult.

For this reason, in the past, a plurality of control valves were combined, but flow rate-pressure control was achieved using an electrical closed loop. This has resulted in problems such as a complicated structure, an increase in space, an increase in cost, and a shock when changing control.

(Object of the Invention) In view of the problems of the prior art, it is an object of the present invention to provide a flow rate pressure control valve that is simple in structure, takes up little space, and is inexpensive.

(Solving Means by the Invention) The supply pressure P at the other end is different from the pressure Pi at the equilibrium position of the positioning springs arranged on both sides and the electro-hydraulic converter provided at one end.
It has one main spool that maintains a neutral point by opposing the s, and when controlling the flow rate, it uses only the pressure controlled by the electro-hydraulic converter, and when controlling the pressure, the pressure is controlled by the electro-hydraulic converter. The opening degree of the main spool is controlled by both the pressure and the control pressure Pc that opposes the pressure.

(Example) This will be explained based on the drawings. Reference numeral 1 denotes an electro-hydraulic conversion section, which adjusts the aperture using a coil 1a and a positioning spring 4 to control the pressure P□. 2 is a main spool, 3 is a positioning spring provided on both sides of the main spool 2, Ps is a supply pressure, and Pc is a control pressure applied to a load. Also, there is a constant pressure difference ΔP between the control pressure Pc and the supply pressure Ps' to the main spool.
In addition, it is also possible to compensate for the influence of load fluctuations when controlling the flow rate.

The pressure receiving area A at the end of the main spool 2 by the electro-hydraulic converter 1
The main spool 2 is thereby driven by controlling the pressure P acting on the main spool 2. The main spool 2 is placed so as to maintain a neutral point by a positioning spring 3.3 in a state where no pressure is applied, and the equilibrium pressure of Pl at the neutral point (maintained by a positioning spring 4) of the electro-hydraulic converter 1 is maintained. A supply pressure Ps is applied to the pressure receiving area A2 at the other end of the main spool 2 so as to be balanced with P□ (AIP□=8 Ps).

(Operation) When controlling the flow rate: Use this control valve to keep the pressure receiving area A3 of the main spool 2 in a state where no pressure is applied (to derive the tank pressure PT).At this time, the main spool 2 is controlled from the equilibrium pressure Pi. The spring force of the positioning springs 3, 3 (kn
A, (p, -pt) =
+Kaχ2. This makes it possible to control the opening degree.

When controlling the pressure: Also, the switching unit 5 is switched so that the load pressure Pc is applied to the pressure receiving surface A1 of the main spool 2. 29 allows the load pressure Pc to be directly fed back to the spool 2 by hydraulic pressure, making pressure control possible. The amount of change in pressure P1 and the pressure control range of load pressure Pc are based on main spool 2.
It can be adjusted by the ratio of the pressure receiving area A1°A. Thereby, it is possible to control the load pressure within a range of PcttO=Ps within a certain limited pressure P1 range.

(Effects) 1) By switching the pressure acting on the end of one main spool 2 to Pl or Pc, flow rate control and pressure control can be switched.

2) The ratio between the equilibrium pressure P□ of the electro-hydraulic converter 1 and the supply pressure Ps can be designed by the ratio of the pressure receiving areas A□ and A3 of the spool.

3) Pressure change amount P1wax −P,wi of electro-hydraulic converter 1
n and the controllable range Pcmax of the control pressure Pc to the load
The ratio of Pcin can be designed by the ratio of A1 and Ac.

4) Based on 2) and 3), in the design of the electro-hydraulic converter 1, P
By being able to freely set the amount of change ΔP□ from the equilibrium pressures Pi and Pl of □, an extremely compact and high-performance flow rate pressure control valve was obtained.

[Brief explanation of the drawing]

The figure is a sectional view of a flow rate pressure control valve according to the present invention. In the figure: 1 Electro-hydraulic converter 2 Main spool 3 Positioning spring 4 Positioning spring 5 Switching section A, At, A3 Pressure receiving area Ps of main spool
Supply pressure P, tank pressure P□ Pressure controlled by the electro-hydraulic converter Pc More than the control pressure given to the actuator Applicant Sumitomo Heavy Industries, Ltd. Sub-Attorney Patent Attorney Isamu Ohashi Procedural Amendment Form) 1989 April 7th Director General of the Patent Office Yoshi 1) Moon Yi 1, Indication of the case 1988 Patent Application No. 275730 2, Name of the invention Flow rate pressure control valve 3, Person making the amendment '' Relationship to the case Patent applicant Address: 2-2-1 Otemachi, Chiyoda-ku, Tokyo Name (
210) Sumitomo Heavy Industries Co., Ltd. 4, sub-agent 6, the specification and drawings to be amended 7, the content of the amendments (Patent Application No. 62-275730) 1, the drawings are amended as shown in the attached sheet. (Add the text ``Figure 1'') 2. On page 6 of the specification, line 5, ``Figure 1 is...'' should be changed to ``Figure 1 is...''. Applicant Sumitomo Heavy Industries, Ltd. Sub-Agent Patent Attorney Isamu Ohashi

Claims (2)

[Claims] (1) One main unit that maintains a neutral point by opposing the supply pressure Ps at the other end to the pressure P_1 at the equilibrium position of the positioning springs arranged on both sides and the electro-hydraulic converter installed at one end. It has a spool, and when the flow rate is controlled, the pressure P_1 is controlled by the electro-hydraulic converter, and when the pressure is controlled, the pressure is controlled by the electro-hydraulic converter, and the control pressure Pc that opposes the pressure is controlled by the electro-hydraulic converter.
A flow rate pressure control valve characterized in that a main spool is driven by both. (2) The flow rate according to claim 1, characterized in that a valve for switching feedback pressure is provided inside or outside the control valve, thereby switching the control target of the valve between flow rate and pressure. Pressure control valve.