JP2561839Y2 - Pressure control valve with built-in pressure compensation spool with flow control function - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control valve for reducing a shock generated when hydraulically braking a large inertia force in turning or running a construction machine.

[0002]

2. Description of the Related Art When starting and braking are performed in a turning and traveling circuit of a construction machine, surge pressure is generated in a starting and braking side circuit in a conventional relief valve, and this is a relief valve. However, since the predetermined set load by the spring is acting on the poppet, the poppet cannot be opened quickly, and the circuit becomes instantaneously high in pressure, causing not only a large shock but also a large shock. However, there is a disadvantage that an excessive load is applied to each hydraulic device.

[0003]

SUMMARY OF THE INVENTION The present invention provides a pressure control valve which greatly reduces shock generated by a sudden increase in pressure when hydraulically braking a large inertial force in turning or traveling of a construction machine. The purpose is to do.

[0004]

A piston which can slide a predetermined stroke on the other end of a pressure setting spring 8 for pressing a poppet 5 of a pressure control valve having two oil passages which are connected or disconnected. 9, a pressure compensating spool 12 is provided in the piston 9, and the pressure oil flowing from the poppet 5 through the orifice 6 is supplied to the pressure compensating spool 12.
Between the pressure oil flowing out through the flow control unit A and the pressure oil flowing out through the orifice 15 provided downstream of the flow control unit A by the flow control unit A of the pressure compensation spool 12. By acting on the opening area decreasing side and the opening area increasing side, respectively, the force generated by the differential pressure is opposed to the compression spring 16 of a predetermined spring constant provided on the opening area increasing side of the spool 12, and balanced. The set pressure was gradually increased so that the set pressure became maximum at the stroke end. The preset amount of the compression spring 16 for pressure compensation in the pressure compensation spool can be easily adjusted and replaced from outside.

[0005]

FIG. 1 shows an embodiment of the present invention. 1 is a high pressure chamber, 2 is a low pressure chamber, 3 is a sheet of a poppet 5, and 4 is a slot.
The poppet 5 slides in this. Reference numeral 6 denotes an orifice provided at the top of the poppet, 7 denotes a poppet spring receiver, 8 denotes a compression spring for setting a relief pressure, and one end of the poppet spring receiver 7.
The other end is in contact with a spring seat 9b provided in the piston 9. 9 is a piston and 10 is a cylinder. 11 is a pressure compensating housing, 11a is a drilled hole, and 12 is a pressure compensating spool provided with a flow control unit A. Reference numerals 13 and 14 denote oil passages leading to the pressure control unit, and reference numeral 15 denotes an orifice provided at the lower end of the spool 12. A compression spring 16 for pressure compensation is mounted between the spool 12 and the spring receiver 18. 17
Is an oil passage connecting the oil chambers 25 and 26. 19 is a piston receiver, 20 is a nut, 21 is an initial relief pressure adjusting screw, 21a is a drilled hole, 22 is a nut, and 23 is a step-up time adjusting screw. Can be. 24 is a housing.

When pressure oil enters the high-pressure chamber 1 in FIG. 1, the pressure receiving surface 5a (diameter D ₁ ) in contact with the sheet 3 of the poppet 5 and the rod tip insertion of the piston 9 formed inside the poppet 5 are inserted. A downward force acts on the poppet 5 due to the area difference between the poppet 5 and the section (cross-sectional area D ₂ ), overcoming the relief pressure setting compression spring 8 pressing the poppet 5 against the sheet 3 and moving the poppet 5. The valve is opened, and an attempt is made to release the pressure oil to the low-pressure chamber 2.
Almost simultaneously, the pressurized oil is supplied to the relatively large oil passages 9a and 14, 13
And acts on the end face 12a of the pressure compensating spool 12. The oil chamber 25 communicates with the oil chamber 26 through the oil passage 17 through the orifice 15. At this time, a differential pressure is generated between the spool end surface 12a and the oil chamber 25 by the orifice 15, and this differential pressure overcomes the pressure compensating compression spring 16, and the spool is moved to a position where the differential pressure and the spring force are balanced. 12 is lowered. Thereby, as shown in FIG. 3, the oil passage 14 provided in the pressure compensation housing 11 and the oil passage 1 provided in the spool 12 are provided.
The gap between the orifice 15 and the orifice 15 is constantly controlled to control the flow rate.

That is, a constant flow can always be supplied to the oil chamber 26 regardless of any pressure fluctuations in the high-pressure chamber 1. Further, the piston 9 constituting the oil chamber 26 is configured so that the pressure oil guided to the oil chamber 26 acts on the restoring force of the compression spring 8 acting on the piston 9 and the pressure oil acting on the rod end D ₂ of the piston 9. The piston 9 has a large pressure receiving area so that the piston 9 can be lifted by overcoming the pressure. As described above, since the pressure oil in the high pressure chamber 1 flows into the oil chamber 26 at a constant speed, the piston 9 is moved from the low pressure setting position (FIG. 1) to the high pressure setting position (FIG. 4) at a constant speed. Therefore, FIG.
As shown in (b), the setting of the relief pressure on the high pressure chamber side can be increased with a certain gradient from low pressure to high pressure.

Next, a mechanism for adjusting the preset amount of the pressure compensating compression spring 16 will be described with reference to the circuit shown in FIG.
The flow rate Q through the orifice 15 in the circuit diagram is given by:

[0009]

(Equation 1)

Here, C: flow coefficient, A: orifice 1
5, opening area, P ₁ -P ₂ : pressure difference before and after the orifice,
ρ: oil density. An approximate expression indicating the equilibrium state of the pressure compensation spool 12 is as follows:
_{k (χ 0 + χ) +} P 2 a = P 1 a ··· (2) k: spring constant of the pressure compensating compression spring 16, chi _0: preset length, chi: spool - stroke Le 12 - click amount, a: Indicates the cross-sectional area of the spool 12. By transforming the above equation (2),

[0011]

(Equation 2)

By substituting equation (3) into equation (1),

[0013]

(Equation 3)

## EQU1 ## Since the moving speed of the piston 9 is determined by the increase and decrease of Q, the speed at which the relief pressure is increased, that is, the slope, is changed by increasing and decreasing the spring force k (χ ₀ + χ) of the compression spring 16 in the equation (4). It is possible to do. Here, since the stroke amount の of the spool 12 at which the opening area of the variable diaphragm portion is fully closed is always constant, the preset length χ ₀ of the compression spring 16 is made variable to increase or decrease the spring force. Can be.

In the embodiment shown in FIG.
1 and the initial relief pressure adjusting screw 21 are provided with drilled holes 11a and 21a, respectively, and a nut is inserted by inserting a round bar or the like to prevent idling of the housing 11 in the cylinder 10, thereby loosening the nut 22. the screw -23 rotated to adjust the preset length chi ₀ by moving the spring receiver 18. In the present embodiment, the adjusting mechanism is provided by the adjusting screw. However, by using a mechanism in which the pilot pressure is opposed to the spring receiver 18 to increase or decrease the spring force, any pressure control can be performed. For example, by detecting the moving speed and the inertial force of a machine, it becomes possible to provide an optimum braking action to the machine.

[0016]

The pressure oil flowing from the poppet 5 through the orifice 6 is passed through the flow control unit A, and the pressure oil flowing out of the poppet 5 through the orifice 15 provided downstream of the flow control unit A. Oil acts on the opening area decreasing side and increasing side of the flow control unit A of the pressure compensating spool 12, and a force generated by the differential pressure is applied to the opening area increasing side of the spool 12 by a predetermined spring constant. By balancing the pressure spring against the pressure compensating compression spring 16, a pressure compensating spool capable of controlling the flow rate is built in, and the pressure can be adjusted. Since the presetting of the pressure compensating compression spring 16 can be easily performed from the outside, an ideal relief waveform suitable for the machine can be output.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is a detailed view of a flow control unit in FIG. 1;

FIG. 3 shows a state in which a pressure compensation spool with a flow control function 12 is operated.

FIG. 4 shows the stroke end or release of the piston 9;
3 shows a high pressure high pressure setting.

FIG. 5 shows a conventional relief pressure waveform and a waveform of the present invention.

6A is a circuit diagram of a known circuit, and FIG. 6B is a circuit diagram of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 High pressure chamber 2 Low pressure chamber 3 Sheet 4 Sleeve 5 Poppet 6 Orifice 7 Spring receiver for poppet 8 Compression spring 9 Piston 9b Spring seat 10 Cylinder 11 Housing 12 Pressure compensation spool 13, 14 Oil passage 15 Orifice 16 Compression Spring 17 Oil passage 18 Spring receiver 19 Piston receiver 20 Nut 21 Adjust screw 21a Drilled hole 22 Nut 23 Adjust screw 24 Housing 25, 26 Oil chamber A Flow control unit

Claims (2)

(57) [Scope of request for utility model registration] 1. A pressure setting spring for pressing a poppet (5) of a pressure control valve having two oil passages which are connected or disconnected.
The other end of (8) can be slid to a predetermined stroke.
A pressure compensating spool (12) is provided in the piston (9) in contact with the spring seat (9b) provided in (9), and the pressure oil flowing from the poppet (5) through the orifice (6). The pressure compensation spool
The pressure oil flowing out through the flow control unit (A) of (12) and the pressure oil flowing out through the orifice (15) provided downstream of the flow control unit (A) are subjected to the flow control. A compression spring (16) for pressure compensation having a predetermined spring constant provided on the increased opening area of the spool (12) by acting on the decreasing area and increasing side of the opening area of the portion (A), respectively. A pressure compensating spool with a flow control function, characterized in that the set pressure of the pressure control valve is gradually increased so that the set pressure becomes maximum at the stroke end by balancing against the pressure. Built-in pressure control valve. 2. The flow rate according to claim 1, wherein the adjustment and replacement of the preset amount of the pressure compensating compression spring in the pressure compensating spool can be easily performed from outside. Pressure control valve with built-in pressure compensation spool with control function.