JPH0577603U - Hydraulic pilot pressure reducing valve - Google Patents

Abstract

(57) [Summary] [Purpose] The hydraulic pilot pressure reducing valve allows the operator to detect the load condition of the working machine. [Arrangement] The valve body 10 is provided with a pressure reducing valve, a piston, a piston pushing member 18, and an operating lever 19, and by operating the operating lever 19, the pressure reducing valve reduces the pressure at the inlet port and outputs the pressure to the outlet port. A cylinder hole 20 is formed in the valve body 10, and a free piston 21 is fitted and inserted in the cylinder hole 20 to form a raising chamber 22, and an operating piston 23 in contact with an upper portion of the free piston 21 is attached to a lower surface of a piston pushing member 18. The load-sensing cylinder 24 is pressed by pressing to the discharge chamber 2a of the hydraulic pump 2 and the piston pushing member 18 is pushed toward the neutral position by the pump discharge pressure to feed back to the operating lever 19.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is a hydraulic pilot decompression for supplying switching pilot pressure oil to an operation valve that supplies pressure oil to a work machine cylinder that operates a work machine mounted on a construction machine such as a wheel loader, a dump truck, and a bulldozer. Regarding the valve.

[0002]

[Prior Art]

 As an operation valve that supplies pressure oil to the working machine cylinder of construction machinery, a spool is provided in the valve body so as to be slidable between the neutral position and the pressure oil supply position, and the spool is held at the neutral position by a spring. At the same time, a pilot-operated operation valve that slides to the pressure oil supply position with pilot pressure oil supplied to the pressure receiving part is known. I try to supply pressure oil. Such a hydraulic pilot valve is equipped with a pressure reducing valve, a piston for operating the pressure reducing valve, a member for pushing the piston, and an operating lever for operating the piston pushing member in the valve body. By doing so, the piston is slid by the pushing member to operate the pressure reducing valve, reducing the inlet pressure and outputting pilot pressure oil, and the pressure of the pilot pressure oil that is output is proportional to the operation stroke of the operating lever. To do. On the other hand, the pilot-operated operation valve slides the spool to the pressure oil supply position in proportion to the pressure of the pilot pressure oil supplied to the pressure receiving part, so the opening degree of the operation valve (area connecting the inlet and the outlet) ) Is proportional to the operation stroke of the operation lever.

[0003]

[Problems to be solved by the device]

 The discharge oil of the hydraulic pump driven by the engine is supplied to the inlet of the operation valve, and the flow rate proportional to the opening of the operation valve is supplied to the working machine cylinder, so the operation stroke of the operation lever of the hydraulic pilot pressure reducing valve Although the work machine can be moved by the amount equivalent to, the main hydraulic system that connects the hydraulic pump, the operating valve and the work machine cylinder, and the pilot hydraulic system that connects the hydraulic pilot pressure reducing valve and the pressure receiving part of the operating valve Separately, the pilot hydraulic system pressure does not change at all even if the discharge pressure of the hydraulic pump changes due to the operating pressure of the working machine cylinder changing depending on the load condition of the working machine. It is not possible to detect the load condition of the operator, and it takes time for the operator to feel the work feeling such as when the work condition or the site changes. That is, when the load on the work equipment is large and when the work equipment load is small, the work speed of the work equipment cylinder is different even if the opening of the operation valve is the same, and the work equipment speed is different even if the operation lever is operated by the same stroke. I have a sensation.

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

[0005]

[Means for Solving the Problems]

 The valve body 10 is provided with a load sensing cylinder 24 that pushes the piston pushing member 18 toward the neutral position by the pressure in the raising chamber 22, and a hydraulic pilot that supplies pump discharge pressure or working machine cylinder working pressure to the raising chamber 22. Pressure reducing valve.

[0006]

[Work]

 Since the piston pushing member 18 is pushed toward the neutral position by the pump discharge pressure or the working machine load pressure and can be fed back to the operator via the operating lever 19, the operator can detect the working machine load state.

[0007]

【Example】

 As shown in FIG. 1, the discharge pressure oil of the hydraulic pump 2 driven by the engine 1 is supplied to the working machine cylinder 4 by the pilot operated operation valve 3, and the pressure receiving portion of the pilot operated operation valve 3 is provided. Pilot pressure oil is supplied to 3a by a hydraulic pilot pressure reducing valve 5. The discharge pressure oil of the auxiliary hydraulic pump 6 driven by the engine 1 is supplied to the hydraulic pilot pressure reducing valve 5, and its inlet pressure is reduced to be supplied to the pressure receiving portion 3a of the operation valve 3.

Next, details of the hydraulic pilot pressure reducing valve 5 will be described. As shown in FIGS. 2, 3, and 4, the valve body 10 is provided with four pressure reducing valves 11 and four pistons 12. The pressure reducing valve 11 connects the inlet port 13 and the outlet port 14 to each other. The spool 15 for shutting off is held by a spring 16 at the shut-off position, and the spool 15 is pushed by the piston 12 to set the communicating position to supply the pressure oil from the output port 14 to the inlet port 13. A piston pushing member 18 is provided on the valve body 10 via a joint 17 so as to be swingable back and forth and left and right, and an operating lever 19 is attached to the piston pushing member 18. A cylinder hole 20 is formed in the valve body 10 near each piston 12, and a free piston 21 is fitted and inserted into each cylinder hole 20 to form a raising chamber 22. An operating piston in contact with the upper surface of the free piston 21. Reference numeral 23 makes contact with the lower surface of the piston pushing member 18 to form a load sensing cylinder 24, and the raising chamber 22 is connected to the discharge passage 2a of the hydraulic pump 2 to be supplied with pump discharge pressure. The load chamber 22 may be supplied with the load pressure of the working machine cylinder 4.

Next, the operation will be described. The operating piston 23 is pushed up via the free piston 21 by the pump discharge pressure supplied to the raising chamber 22, and the piston pushing member 18 is given a force toward the neutral position. When the operating lever 19 is operated to swing the piston pushing member 18, the piston 18 is pushed and the spool 15 slides to reduce the pressure of the inlet port 13 and output it to the outlet port 14, and the pilot pressure oil is piloted. The pressure oil is supplied to the pressure receiving portion 3a of the actuated operation valve 3 to the pressure oil supply position, and the pressure oil discharged from the hydraulic pump 2 is supplied to the working machine cylinder 4. When the load condition of a work machine (not shown) operated by the work machine cylinder 4 changes significantly, the working pressure of the work cylinder 4 changes to a high level and the discharge pressure of the hydraulic pump 2 changes to a high level. As a result, the pressure in the raising chamber 22 of the load sensing cylinder 24 is changed to a high level, the force for pushing the piston rocking member 18 to the neutral position is greatly changed, and the operation lever 19 is fed back to the operation operator. The load of the work machine can be detected by the operating force of the operating lever 19.

[0010]

[Effect of the device]

 Since the piston pushing member 18 is pushed toward the neutral position by the pressure supplied to the raising chamber 22 of the load sensing cylinder 24, the force is fed back to the operating lever 19 so that the operator can sense the working machine load state.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram including a hydraulic pilot pressure reducing valve.

FIG. 2 is a plan view of a hydraulic pilot pressure reducing valve.

3 is a cross-sectional view taken along the line AA of FIG.

4 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

2 ... hydraulic pump, 3 ... pilot work type operation valve, 4 ...
Working machine cylinder, 5 ... Hydraulic pilot pressure reducing valve, 10 ... Valve body, 11 ... Pressure reducing valve, 12 ... Piston, 13 ... Inlet port, 14 ... Outlet port, 15 ... Spool, 16 ... Spring,
17 ... Joint, 18 ... Piston pushing member, 19 ... Operating lever, 20 ... Cylinder hole, 21 ... Free piston, 2
2 ... Lifting chamber, 23 ... Working piston, 24 ... Load sensing cylinder.

Claims (2)

[Scope of utility model registration request] 1. A pressure reducing valve 11 and a piston 12 in a valve body 10.
In the hydraulic pilot pressure reducing valve for providing the piston pushing member 18 and the operating lever 19, and depressing the piston pushing member 18 by the operating lever 19 to reduce the pressure of the inlet port 13 by the pressure reducing valve 11 and outputting the pressure to the outlet port 14, The valve body 10 is provided with a load sensing cylinder 24 for pushing the piston pushing member 18 to a neutral position by the pressure in the raising chamber 22,
A hydraulic pilot pressure reducing valve configured to supply pump discharge pressure or working machine cylinder load pressure to the raising chamber 22. 2. A cylinder hole 20 is formed in the valve body 10,
A load sensing cylinder 24 is formed by inserting a free piston 21 into the cylinder hole 20 to form a raising chamber 22, and an operating piston 23 in contact with an upper portion of the free piston 21 is in contact with a lower surface of a piston pushing member 18. The described hydraulic pilot pressure reducing valve.