JPH0587609U - Pressure control valve with built-in pressure compensation spool with flow rate control function - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention provides a pressure control valve that significantly reduces the shock caused by a sudden pressure increase when hydraulically braking a large inertial force during turning or traveling of a construction machine. The purpose is to do. [Structure] The pressure oil flowing from the poppet 5 through the orifice 6 is passed through the flow rate control unit A, and the pressure oil flowing out of the flow rate control unit A and the orifice 15 provided downstream of the pressure oil from the flow rate control unit A are provided. The pressure oil flowing out through the pressure compensating sp
The force generated by the differential pressure is made to act on the decreasing side and increasing side of the opening area of the flow rate control unit A of the spool 12, and counterbalances the compression spring 16 having a predetermined spring constant provided on the increasing side of the opening area of the spool 12. By doing so, the set pressure of the pressure control valve was gradually increased so that the set pressure became the highest at the stroke end.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pressure control valve for reducing a shock generated when hydraulically braking a large inertial force during turning or traveling of a construction machine.

[0002]

[Prior Art]

 When starting and braking in the turning and running circuits of a construction machine, serge pressure is generated in the starting and braking side circuits in the conventional relief valve, and this acts on the poppet of the relief valve. However, the poppet cannot be opened rapidly because the preset load by the spring is operating on the poppet, and the above circuit momentarily becomes a high pressure, causing a large shock and not only for each hydraulic equipment. It had the drawback of overloading the.

[0003]

[Problems to be solved by the device]

 An object of the present invention is to provide a pressure control valve that significantly reduces a shock caused by a sudden pressure increase when hydraulically braking a large inertial force during turning or traveling of a construction machine.

[0004]

[Means for Solving the Problems]

 The other end of the pressure setting spring 8 that presses the poppet 5 of the pressure control valve having two oil passages that are communicated or cut off is connected to the spring seat 9b provided on the piston 9 that is capable of stroking a predetermined stroke. A pressure compensating spool 12 is provided inside the piston 9 so that the pressure oil flowing from the poppet 5 through the orifice 6 flows out through the flow rate control section A of the pressure compensating spool 12, The pressure oil that has flowed out through the orifice 15 provided downstream of the flow rate control unit A is caused to act on the decreasing side and the increasing side of the opening area of the flow rate controlling unit A of the pressure compensating spool 12, respectively. The force generated by the pressure is opposed to and balanced by the compression spring 16 having a predetermined spring constant provided on the side of the opening of the spool 12 where the opening area is increased, so that the set pressure of the pressure control valve is gradually increased to the stroke end. So that the set pressure becomes maximumFurther, the preset amount of the compression spring 16 for pressure compensation in the pressure compensation spool can be easily adjusted and exchanged from the outside.

[0005]

【Example】

 FIG. 1 shows an embodiment of the present invention. 1 is a high pressure chamber, 2 is a low pressure chamber, 3 is a seat of the poppet 5, 4 is a sleeve, and the poppet 5 slides in this. 6 is an orifice provided at the top of the poppet, 7 is a poppet spring receiver, 8 is a relief pressure setting compression spring, and one end is the poppet spring receiver 7 and the other end is a spring seat 9b provided in the piston 9. Abutting against. 9 is a piston and 10 is a cylinder. Reference numeral 11 is a pressure compensating housing, 11a is a blind hole, and 12 is a pressure compensating spool having a flow rate control unit A. Reference numerals 13 and 14 are oil passages communicating with the pressure control unit, and 15 is an orifice provided at the lower end of the spool 12. Reference numeral 16 is a compression spring for pressure compensation, which is mounted between the spool 12 and the spring receiver 18. An oil passage 17 connects the oil chambers 25 and 26. Reference numeral 19 is a piston receiver, 20 is a nut, 21 is an initial relief pressure adjusting screw, 21a is a drill hole, 22 is a nut, and 23 is a pressurizing time adjusting screw. be able to. 24 is a housing.

Now, in FIG. 1, when the pressure oil enters the high pressure chamber 1, the pressure receiving surface 5 a (diameter D ₁ ) in contact with the sheet 3 of the poppet 5 and the rod tip of the piston 9 formed inside the poppet 5 A downward force acts on the poppet 5 due to the area difference from the end insertion portion (cross-sectional area D ₂ ), which causes the relief pressure setting compression spring 8 that presses the poppet 5 against the sheet 3. Overcome and open the poppet 5 to open the pressure oil to the low pressure chamber 2. At about the same time, the pressure oil travels through the relatively large oil passages 9a, 14 and 13 and acts on the end face 12a of the pressure compensating spool 12. Further, it communicates with the oil chamber 26 from the oil chamber 25 through the oil passage 17 through the orifice 15. At this time, a pressure difference is generated between the spool end surface 12a and the oil chamber 25 by the orifice 15, and this pressure difference overcomes the pressure compensating compression spring 16 to reach the position where the pressure difference and the spring force are balanced. Lower the lever 12. As a result, as shown in FIG. 3, a gap occurs between the oil passage 14 provided in the pressure compensating housing 11 and the oil passage 13 provided in the spool 12, which serves as a variable throttle portion to control the flow rate. , Operates so that the pressure difference before and after the orifice 15 is always constant.

That is, a constant flow rate can always be supplied to the oil chamber 26 regardless of any pressure fluctuation in the high pressure chamber 1. Further, in the piston 9 forming the oil chamber 26, 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 rod tip portion D ₂ of the piston 9. It has a large pressure receiving area in advance so that the piston 9 can be raised by overcoming the pressure oil. As described above, the pressure oil on the high pressure chamber 1 side flows into the oil chamber 26 at a constant speed, so that 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, as shown in FIG. 5B, the setting of the relief pressure on the high pressure chamber side can be increased from low pressure to high pressure with a certain inclination.

Next, the preset amount adjusting mechanism of the pressure compensating compression spring 16 will be described with reference to the circuit of FIG. 6B. The flow rate Q passing through the orifice 15 in the circuit diagram is given by the following equation.

[0009]

[Equation 1]

Here, C is the flow coefficient, A is the opening area of the orifice 15, P ₁ -P _{2 is} the pressure difference before and after the orifice, and ρ is the oil density. Further, the approximate equation showing the equilibrium state of the pressure compensation spool 12 is k (χ ₀ + χ) + P ₂ a = P ₁ a (2) k: the spring constant of the pressure compensation compression spring 16, χ ₀ : Preset length, χ: stroke amount of the spool 12, and a: cross-sectional area of the spool 12. By transforming the above equation (2),

[0011]

[Equation 2]

Substituting equation (3) into equation (1),

[0013]

[Equation 3]

[0014] Since the moving speed of the piston 9 is determined by the increase / decrease of Q, the increase speed of the relief pressure, that is, the inclination is changed by increasing / decreasing the spring force k (χ ₀ + χ) of the compression spring 16 in the equation (4). It becomes possible. Here, since the stroke amount χ of the spool 12 at which the opening area of the variable throttle portion is fully closed is always constant, the spring force is increased or decreased by making the preset length χ ₀ of the compression spring 16 variable. Can be made

In the embodiment of FIG. 1, the pressure compensating housing 11 and the initial relief pressure adjusting screw -21 are provided with drill holes 11a and 21a, respectively, and a round bar or the like is inserted thereinto, so that the housing 11 inside the cylinder 10 is inserted. The preset length χ ₀ is adjusted by loosening the nut 22 by preventing the idling of No. 2, rotating the adjusting screw 23 and moving the spring receiver 18 while increasing the pressure. In this embodiment, an adjusting mechanism using an adjusting screw is used, but by using a mechanism in which the pilot pressure is opposed to the spring receiver 18 to increase or decrease the spring force, it is possible to perform any pressure control. For example, by detecting the moving speed or inertial force of a machine, it becomes possible to apply the optimum braking action to the machine.

[0016]

【effect】

 The pressure oil flowing from the poppet 5 through the orifice 6 flows through the flow rate control unit A, and the pressure oil flows out through the orifice 15 provided downstream of the flow rate control unit A. Are applied to the decreasing side and the increasing side of the opening area of the flow rate control unit A of the pressure compensating spool 12, and the force generated by the differential pressure is applied to the increasing side of the opening area of the spool 12 with a predetermined spring constant pressure. By compensating against the compensating compression spring 16 and balancing it, a pressure compensating spool that enables flow rate control was built in, enabling pressure adjustment. Since the pressure compensating compression spring 16 can be easily preset from the outside, it is possible to output an ideal relief waveform suitable for the machine.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention.

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

FIG. 3 shows a state in which a pressure compensating spool 12 with a flow rate control function operates.

FIG. 4 Stroke end or release of piston 9
High pressure High pressure setting is shown.

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

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

[Explanation of symbols]

1 High-pressure chamber 2 Low-pressure chamber 3 Seat 4 Sleeve 5 Poppet 6 Orifice 7 Poppet spring receiver 8 Compression spring 9 Piston 9b Spring seat 10 Cylinder 11 Housing 12 Pressure compensating 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 Clearance hole 22 Nut 23 Adjust screw 24 Housing 25, 26 Oil chamber A Flow control section

Claims (2)

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