JPS58121303A - Control circuit device for flow rate - Google Patents

Abstract

PURPOSE:To improve stability by setting up a changeover valve with meter-out throttle and a reducing valve in the circuit device controlling flow rate to an actuator. CONSTITUTION:When a fluid flows in the direction of the arrow in a supply and discharge circuit 2, pressure P1 which must be generated in a pilot circuit 7 corresponds to a value obtained by adding pressure P3 at the upstream side of the throttle of the changeover valve 6 to a value P2 acquired by dividing the spring force of a counterbalance valve 5 by the pressure receiving area of the piston. Pressure P1 is equal to a value obtained by adding a value P4 acquired by dividing the spring force of the reducing valve 8 by the area of the piston and pressure P5 at the downstream side of the throttle of the changeover valve 6, and pressure difference P3-P5 before and behind throttle at the meter-out side of the changeover valve 6 in case of the lowering of load is equal to pressure difference P4-P3. Pressure difference P3-P5 is also made approximately constant because pressures P4, P2 are approximately of constant values, and flow rate passing through the circuit 2 can be controlled without being affected by pressure P6 at the upstream side.

Description

[Detailed Description of the Invention] The present invention controls the flow rate to the actuator of a hydraulic motor. 1 circuit II equipment.

Conventionally, as shown in the diagram of JIII1, there are two pressure oil tank # excitation paths to the actuator field, a counterbalance valve cect is interposed in b, and both circuits #P circuit are interposed, a switching valve d is interposed in b, and the actuator 10 drive system is installed. It is known that the flow rate to the actuator 1 is controlled by an exchange valve d with a pressure compensation valve and a flow rate control 11 function. . If the actuator a is one that causes a negative load change, such as a winch motor O, especially when lowering the negative IFr, the load change II
II, counterbalance valve C9C and pressure compensation valve
The pressure in the pilot circuit f changes and resonates, making control unstable.

The purpose of the present invention is to eliminate such inconveniences, and at 9% O, a counterbalance valve [1! In the type with a switching valve, the scissors switching valve is replaced by a switching valve with a meter-out throttle p, and a ridge pressure valve is connected to the pressure oil supply/discharge a of the counterbalance valve. The establishment shall be nine times t% mold.

According to the drawings, the 211th
KJIte (1) &! The actuator of the positive pressure motor is connected to the actuator (1).
It is wired and the other end is s fm EE @ (8) or tank (
4) Shows the pressure oil supply and discharge 11 connections connected to each boat *git
A well-known Kawanme balance valve (6) (<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<) need to intervene.

The above is almost the same as the conventional circuit, but the present invention is also O
Now, the cough switching valve (6) consists of a switching valve with a meter-out throttle, and this is it! 7flL1 is operated under control, and each counter/throttle valve (51(5)) is provided with a Nonolot circuit (71(7) is a well-known O pressure reducing valve valve). The valve (51 (51) and the circuit (B) (B) K are connected.Furthermore, in the case of melt water, each counter 2 lance valve (51 (51) and each nose lot circuit (7H7) 1 mutually connected) Connect to the pressure reducing valve (
8) is connected to the secondary 11, and the first passage of Kajishin (8) is connected to the shuttle valve installed between the two firewood supply paths (21 (2)). ), whichever higher circuit pressure is extracted and activated.

txh ridge pressure valve) drain switching valve (@) and tank (
4) and [The pilot circuit to be introduced into the return 9 circuit]
do.

Next, the seventh composition meeting will be held. The actuator (1) or the hydraulic motor of the winch operates to lower the load and connects the fluid to the supply/discharge path (21 (in the direction of the arrow KtIL)).
[If you think about it, r! In the known counterbalance valve (5) on the right side in the direction of A, its pilot circuit (7)K
The value P obtained by dividing the pressure to be generated PsFi by the pressure receiving area of the spring wire of the counterbalance valve (i) and its Viaton
3 plus the pressure Ps't-a@ above the throttle O of the switching valve (6). In addition, the pressure P1 in the e-irotto passage (7) is obtained by dividing the spring force of the pressure reducing valve (8) by its piston area. P, is equal to t plus Ik, and thus the meter-awat side throttle p of the switching valve (6) when lowering the load.
The pre-value pressure difference P, -P, is equal to P, -P. These P4. Since P is a nearly constant value, the applied pressure difference P3-P is approximately constant as much as possible. The balance valve (&) IZ) can perform pressure compensation type flow rate 114 control without being affected by the influence of the upstream pressure P. In other words, it is possible to perform pressure compensation type flow rate 114 control without being influenced by the cost of #i cough pressure P6.

In this way, according to the present invention, the switching valve [meter arrangement] #
1IIIL with attached one and counter 79277
A pressure-compensated flow rate of 1111141t is achieved by interposing a pressure-reducing valve in the pilot circuit of the square, eliminating the need to provide a pressure-compensating valve that tends to resonate.

Furthermore, since the pressure of the cough counterbalance valve is determined by the setting of the pressure reducing valve, it is not affected by load fluctuations and has the effect of improving stability.

[Brief explanation of the drawing]

FIG. 1 is a conventional @1) diagram, and FIG. 2 is a 111 diagram of an example of the present addressing device O1. {Old Actuator, (21 (! Pressure oil supply and discharge 1
L (Wound (6)...Counter balance valve. (6)...Switching valve, (71 (7)...
pilot circuit. (8)...Pressure reducing valve. Patent applicant: Uchida Hydraulic Equipment Industry Co., Ltd.
People: Kin Kitamura and 2 others

Claims (1)

[Claims] In the type in which a counterbalance valve and a switching valve are interposed in the O-pressure oil supply/discharge circuit to the actuator, it is composed of a switching valve with l [switching valve pipe meter ac) @9, and the counterbalance valve OfE oil supply #g1 This is a flow rate control device characterized by having a pressure reducing valve installed in the Neulot excitation valve, which is integrated into the flow control system II.