JPH02286902A - Hydraulic circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic circuit that supplies pressure oil discharged from one hydraulic pump to a plurality of hydraulic actuators.

[Conventional technology]

In order to supply pressure oil discharged from one hydraulic pump to multiple hydraulic actuators, it is sufficient to provide multiple operating valves in the discharge path of the hydraulic pump and supply pressure oil to each hydraulic actuator by switching the operating valves. However, in this case, when pressure oil is supplied to a plurality of hydraulic actuators at the same time, pressure oil is supplied only to the hydraulic actuators with a small load, and no pressure oil is supplied to the hydraulic actuators with a large load.

As a hydraulic circuit that solves this problem, for example, JP-A-59
The one shown in Japanese Patent No. 197603 has been proposed.

This hydraulic circuit is schematically shown in FIG. - The first and second circuits 7.8 to which the second hydraulic actuator 5.6 is connected
Second pressure compensation valves 9 and 10 are provided, and the load pressures P, P2 of the first and second hydraulic actuators 5 and 6 are introduced into the shuttle valve 11, and the higher load pressure is ff! Acting on the 1 and 2nd pressure compensation valves 9 and 10, the pressure is set to match the high load pressure, and the outlet side pressures of the 1st and 2nd operation valves 3 and 4 are made equal,
When the first and second operating valves 3.4 are operated simultaneously, pressure oil can be supplied to the first and second hydraulic actuators 5.6 at a branch ratio proportional to the spool opening area of each operating valve.

[Problem to be solved by the invention]

With such a hydraulic circuit, the pressure compensation valve operates immediately according to the load pressure, so if the second hydraulic actuator 6 is operated with a high load while the first hydraulic actuator 5 is operated with a light load, the shuttle valve 11 Since the higher load pressure acts on the spring chamber sides 9a and 10a of the first and second pressure compensation valves 9 and 10 and suddenly increases the set pressure, the passing flow rate suddenly decreases momentarily and the first hydraulic actuator The amount of oil supplied to the first hydraulic actuator 5 decreases momentarily, and the operation of the first hydraulic actuator 5 momentarily slows down, causing an operation shock.

That is, the pressure compensating valve 9.10 is as shown in FIG.
The opening area of the inlet port 12 and the outlet port 13 is increased or decreased by the spool 14, and the spool 14 is pushed in the direction of opening surface planting by the inlet side pressure Po, and the spring 15 and the spring chamber side 9a are
, 10a pushes the spool 14 in the direction of reducing the opening area to make the set pressure equal to the load pressure, and the stroke of the spool 14 causes the opening area to change rapidly as shown in FIG. .

For this reason, when the load pressure suddenly increases, the spool 14 rapidly moves in the direction of reducing the opening area, rapidly reducing the opening area of the inlet port 12 and the outlet port 13, and the amount of oil passing through it suddenly decreases momentarily. .

Therefore, for example, if the first hydraulic actuator 5 is used as the travel motor of a power shovel, and the second hydraulic actuator 6 is used as a work equipment cylinder or swing motor, it is possible to move the work equipment while the power shovel is running, or When turning the revolving structure, the amount of oil supplied to the travel motor momentarily decreases for the above-mentioned reasons, and the rotational speed suddenly slows momentarily, causing a sudden deceleration shock.

Therefore, an object of the present invention is to provide a hydraulic circuit capable of solving the above-mentioned problems.

[Means and 1 action for solving the problem] (1) The load pressure of the hydraulic actuator is applied to the pressure compensation valve through a throttle, so that when the load pressure suddenly increases, the pressure compensation valve is gradually activated. A hydraulic circuit that prevents the opening area from decreasing rapidly.

(2) The inlet port and outlet port of the pressure compensating valve are inserted into the slit groove formed in the spool, and the opening area changes slightly with respect to the spool stroke, so that when the load pressure suddenly increases and the spool moves suddenly. A hydraulic circuit that prevents the opening area from decreasing rapidly.

〔Example〕

As shown in FIG.
a to the first and second pressure compensation valves 9, 1° spring chamber side 9a, 10
A throttle 22 is provided in each of the first and second circuits 20, 21 connected to the spring chamber 20, 21 so that the load pressure gradually acts on the spring chamber sides 9a, 10a.

Therefore, if the second hydraulic actuator 6 is operated under a heavy load while the first/[b pressure actuator 5 is operated under a light load, and the load pressure acting on the shuttle valve 11 suddenly increases, the The load pressure is reduced to a low pressure by the throttle 22 and is applied to the spring chamber sides 9a, 10 of the first and second pressure compensation valves 9.10.
The pressure acting on a gradually increases, and the spools 14 of the first and second pressure compensating valves 9 and 10 gradually move toward a smaller opening area and gradually increase the set pressure, so that the amount of oil passing through increases suddenly. Therefore, the amount of oil supplied to the first hydraulic actuator 5 does not suddenly decrease momentarily, and the operating shock of the first hydraulic actuator 5 is eliminated.

FIG. 2 shows a second embodiment, in which first and second pressure compensation valves 9,
10 The population port 12 and the outlet port 13 are communicated through a slit groove 16 formed in the spool 14, and the opening area changes with the stroke of the spool 14 gently as shown in FIG.

In this way, even if the load pressure suddenly increases and the spool 14 moves rapidly in the direction of decreasing the opening area, the opening area will not suddenly become smaller, so the amount of passing oil will not suddenly decrease momentarily.

〔Effect of the invention〕

(1) The load pressure of the hydraulic actuator acts on the pressure compensation valve through the throttle 22, so when the load pressure increases suddenly, the load pressure that acts on the pressure compensation valve gradually increases, and the opening area of the pressure compensation valve Since the amount gradually decreases, the amount of oil passing through the pipe does not suddenly decrease momentarily.

Therefore, when one hydraulic actuator is operating under a light load and another hydraulic actuator is operated under a heavy load and the load pressure suddenly increases, the amount of oil flowing to one hydraulic actuator may suddenly decrease momentarily. This can prevent the occurrence of operational shock.

(2) The opening area of the inlet port 12 and the outlet port 13 changes slightly with respect to the stroke of the spool 14 of the pressure compensating valve, so even if the load suddenly increases and the spool 14 rapidly moves in the direction of decreasing the opening area, the opening area Since the flow rate gradually decreases, the amount of passing oil does not suddenly decrease momentarily.
゜Therefore, when one hydraulic actuator is operating with a light load and another hydraulic actuator is operated with a heavy load and the load pressure suddenly increases, the amount of oil to one hydraulic actuator will suddenly decrease momentarily. This can prevent the occurrence of operational shock.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, Fig. 2 is a sectional view of a pressure compensation valve, Fig. 3 is a chart showing the relationship between stroke and opening area, and Fig. 4 is a conventional hydraulic circuit diagram. FIG. 5 is a sectional view of the pressure compensation valve, and FIG. 6 is a chart showing the relationship between stroke and opening area. 1 is a hydraulic pump, 2 is a discharge path, 3 and 4 are first and second operation valves, 5 and 6 are first and second hydraulic actuators, 9 and 10
12 is an inlet port, 13 is an outlet port, 14 is a spool, 16 is a slit groove, and 22 is a throttle.

Claims (2)

[Claims] (1) A plurality of operating valves are provided in the discharge path 2 of one hydraulic pump 1, each operating valve supplies pressure oil to a plurality of hydraulic actuators, and a pressure compensation valve is provided on the outlet side of each operating valve. A hydraulic circuit in which each pressure compensation valve is set by the load pressure of the highest pressure hydraulic actuator, characterized in that a restriction 22 is provided in the circuit that leads the load pressure of the hydraulic actuator to the pressure compensation valve. . (2) A plurality of operation valves are provided in the discharge path 2 of one pump 1, each operation valve supplies pressure oil to a plurality of hydraulic actuators, and a pressure compensation valve is provided on the outlet side of each operation valve, and each of these operation valves is provided with a pressure compensation valve on the outlet side of each operation valve. In a hydraulic circuit in which the pressure compensation valve is set by the load pressure of the highest pressure hydraulic actuator, the opening areas of the inlet port 12 and outlet port 13 of the pressure compensation valve are controlled by a slit groove 16 formed in the spool 14. A hydraulic circuit characterized by: