KR20200094012A - Hydraulic valve and working machine having the same - Google Patents

Abstract

According to one aspect of the present invention, a hydraulic valve includes: a sleeve including an inlet for receiving working fluids and an outlet for discharging the working fluids; a plug sealing the rear end of the sleeve; a poppet installed in the sleeve to be movable to open or close a flow path between the inlet and the outlet; a piston combined with the rear end of the poppet to slide in a longitudinal direction of the poppet; an inner piston facing the poppet and inserted into the piston; a first chamber formed between the poppet and the inner piston; a second chamber formed between the sleeve and the inner piston; a shock absorption piston installed in the plug while supporting the rear end of the inner piston; and a third chamber formed between the plug and the shock absorption piston. The inner piston includes a first flow path connecting the first and second chambers, and the shock absorption piston includes a second flow path connecting the second and third chambers. Therefore, the hydraulic valve is capable of relieving an operation shock on the hydraulic valve by having a longer pressure holding time.

Description

Hydraulic valve and work machine including the same{HYDRAULIC VALVE AND WORKING MACHINE HAVING THE SAME}

The present invention relates to a hydraulic valve and a working machine comprising the same.

Working machines can be classified into excavation equipment, loading equipment, transport equipment, loading and unloading equipment, compaction equipment, and foundation construction equipment due to the diversity of work done in industrial sites. Specifically, bulldozers, excavators, loaders, dump trucks, It is a concept that includes a great deal of equipment, such as rollers.

Excavation is the most basic operation in the industrial field. In the case of industrial construction, the ground is excavated to a certain depth to install various structures or to embed pipes or the like in the ground, where the excavator is most often used.

Excavator is a construction machine that performs works such as excavation work to dig the ground at civil engineering, construction, and construction sites, loading work to transport soil, crushing work to dismantle buildings, and stopping work to clear the ground. It is composed of a traveling body and an upper slewing body and a working device that is mounted on the traveling body and rotates 360 degrees.

In addition, the excavator can be used by mounting a suitable working device according to the condition of the soil and rock, the type of work and the use. Buckets for general excavation and earth and sand transportation, breakers for crushing hard ground, rocks, etc., and crushers used for demolition and crushing of buildings are mainly used working equipment for excavators.

In addition to excavators, these working machines are equipped with a front device including a boom and a bucket at the front of the main body to load aggregates such as crushed rock and soil, or a wheel loader used for short-distance transportation, and a forklift used to lift or transport heavy loads. It can be.

In general, an excavator is equipped with a hydraulic system that provides power for driving various types of equipment, and the hydraulic system controls the hydraulic pump that discharges hydraulic oil and the hydraulic motor that operates the motor through the discharged hydraulic oil, and the flow direction and flow rate of hydraulic oil. It is equipped with a hydraulic valve to control and various actuators for mechanical work.

Here, the hydraulic valve performs a function of lowering the pressure of the hydraulic system to a set pressure by opening a flow path to prevent damage due to high pressure and protect the hydraulic system when the pressure generated in the hydraulic system exceeds the set pressure. can do.

However, when a hydraulic shock occurs in the hydraulic system due to the driver's instantaneous operation of the equipment, the hydraulic valve also operates instantaneously, which may cause a problem of transmitting the hydraulic shock to the driver. Accordingly, there is an increasing demand to further improve the shock absorbing function of the hydraulic valve.

The present invention was created to solve the problems of the prior art as described above, and an object of the present invention is to provide a hydraulic valve having an enhanced shock absorbing function and a working machine including the same.

A hydraulic valve according to an aspect of the present invention includes a sleeve including an inlet through which hydraulic oil is introduced and an outlet through which the hydraulic oil is discharged; A plug sealing the rear end of the sleeve; A poppet movably installed inside the sleeve to open and close a flow path between the inlet and the outlet; A piston coupled to the rear end of the poppet and sliding in the longitudinal direction of the poppet; An inner piston facing the poppet and inserted into the piston; A first chamber formed between the poppet and the inner piston; A second chamber formed between the sleeve and the inner piston; A shock absorbing piston installed in the plug while supporting the rear end of the inner piston; And a third chamber formed between the plug and the shock-absorbing piston, wherein the inner piston includes a first flow path communicating the first chamber and the second chamber, and the shock-absorbing piston is the second chamber. And a second flow path communicating the chamber with the third chamber.

Specifically, the first flow path is connected to the second chamber through the side surface of the inner piston, and the first flow path can be opened and closed by a relative movement with the piston covering the side surface of the inner piston.

Specifically, a first elastic member elastically supporting the poppet and the piston, and a second elastic member elastically supporting the shock-absorbing piston and the plug may be further included.

Specifically, when the inner piston and the shock-absorbing piston retreat due to the pressure increase of the hydraulic oil, the second elastic member is compressed and the first flow path is opened to allow the hydraulic oil to flow into the second chamber.

Specifically, when the inner piston and the shock-absorbing piston are advanced by the elastic force of the second elastic member and the expansion of the second chamber, the piston may be advanced and the first elastic member may be compressed.

Specifically, when the first elastic member is compressed, the poppet may retreat due to an increase in pressure at the front end of the poppet and a flow path between the inlet and the outlet may be opened.

Specifically, a stopper provided between the sleeve and the piston to limit sliding of the piston may be further included.

Specifically, the poppet may have a hollow portion connected to the inlet and a poppet flow path communicating the hollow portion with the first chamber.

The working machine according to one aspect of the present invention includes the hydraulic valve.

The hydraulic valve according to the present invention and a working machine including the same, further comprising an inner piston having an orifice structure and a shock-absorbing piston at the rear end of the piston of the hydraulic valve, so that the pressure rise is slower and the pressure holding time is longer, thereby increasing the pressure of the hydraulic valve. Operating shock can be improved.

1 is a view showing a working machine according to an embodiment of the present invention.
2 is a cross-sectional view of a hydraulic device of a working machine including a hydraulic valve according to an embodiment of the present invention.
3 is a cross-sectional view of a hydraulic valve according to an embodiment of the present invention.
4 to 6 are diagrams for explaining the operation of the hydraulic valve of FIG. 3.
7 is a graph for explaining the pressure change of the hydraulic valve according to an embodiment of the present invention.

The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments associated with the accompanying drawings. In addition, it should be noted that, in addition to reference numerals to the components of each drawing in the present specification, the same components have the same numbers as possible, even if they are displayed on different drawings. In addition, in the description of the present invention, when it is determined that detailed descriptions of related known technologies may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a working machine according to an embodiment of the present invention.

Here, the work machine shown in Figure 1 may be an excavator (1), and is not limited thereto, but is only one example for explaining the work machine including the hydraulic valve of the present invention.

As shown in FIG. 1, the excavator 1 according to the present invention includes a lower traveling body 1a, an upper swinging body 1b, a front attachment 1c, a boom 1d, an arm 1e, a bucket 1f ), boom cylinder (1g).

Excavator 1 according to the present invention, the lower traveling body (1a), the upper traveling body (1b) supported by a pivoting material to the lower traveling body (1a), the front attachment (1c) mounted to the upper rotating body (1b) Consisting of, the front attachment (1c) is a boom (1d) supported by up and down moving material on the upper swing body (1b), an arm (1e), arm supported by front and rear moving materials on the end of the boom (1d), arm Bucket (1f), a breaker (not shown), a crem shell (not shown), and a boom cylinder (1 g) driven using hydraulic oil to drive the boom (1d), which are installed at the end of (1e) as front and rear moving materials ).

2 is a cross-sectional view of a hydraulic device of a working machine including a hydraulic valve according to an embodiment of the present invention.

Referring to Figure 2, the hydraulic device 10 of the excavator 1 including the hydraulic valve 100 according to an embodiment of the present invention is a hydraulic valve 100, casing 200, shaft 300, swash plate 400, a piston assay 500, a cylinder block 600, and a valve plate 700. Here, the hydraulic device 10 may be preferably a hydraulic motor, but this is only an example and may be applicable to a hydraulic pump or the like.

The hydraulic device 10 is integrally coupled to the shaft 300, the shaft 300, and a cylinder block 600 in which a plurality of piston assays 500 are spaced in the circumferential direction, and each piston assay 500 ) Is connected to a plurality of pistons 520 having a forward stroke and a retraction stroke according to the rotation of the cylinder block 600 and reciprocating displacement, and a piston assay 500 into which the piston 520 of the forward stroke or the retract stroke is fitted. It may include a valve plate 700.

Specifically, the hydraulic device 10 may include a cylinder block 600 that is rotatably installed in the rotational direction around the axis of the shaft 300, and the casing 200 is provided on the outer surface to provide the hydraulic device 10. To protect the respective parts of the, the hydraulic valve 100 is protruded on one side of the casing 200 is provided.

The cylinder block 600 is provided with a plurality of piston assays 500, and cylinder ports (not shown), which communicate with each of the piston assays 500, are respectively formed, and each piston assay 500 has The piston 520 is fitted.

A piston shoe (510) is installed at one end of each piston (520), and each piston shoe (510) is directed toward the swash plate (400) inclined with respect to a virtual plane perpendicular to the axis of the shaft (300). Pressurized.

Accordingly, each piston 520 has a forward stroke and a retract stroke by synchronizing with the rotation of the cylinder block 600, and can reciprocate. The hydraulic device 10 is subjected to such an forward stroke and a retract stroke, and power is generated through this progress.

When the hydraulic device 100 generates power through the forward stroke and the retract stroke of the piston 520 by the hydraulic oil, the hydraulic device 10 has a predetermined pressure or higher to prevent excessive pressure from being generated therein. When formed inside the device 10, a certain flow rate is bypassed.

3 is a cross-sectional view of a hydraulic valve according to an embodiment of the present invention.

Referring to Figure 3, the hydraulic valve 100 according to an embodiment of the present invention sleeve 110, plug 120, poppet 130, piston 140, inner piston 150, shock relief piston ( 160) and a stopper 170.

Sleeve 110 may be formed to protrude on one side of the casing 200 described above, is formed on the outermost shape of the cylinder to determine the shape of the hydraulic valve 100.

Specifically, the sleeve 110 may have a cylinder shape in which a hollow is formed inside, a poppet 130, a piston 140, an inner piston 150, an impact relief piston 160, and a stopper (which will be described later therein) 170).

The sleeve 110 includes an inlet G1 through which hydraulic oil flows and an outlet G2 through which hydraulic oil is discharged. A valve seat 111 having an inlet G1 may be provided at the front end of the sleeve 110, and a plug 120 that seals the sleeve 110 may be provided at the rear end. Hereinafter, the front end (or front end) will be defined as the direction in which the valve seat 111 is located, and the rear end (or rear end) is the direction in which the plug 120 is located.

The outlet G2 may be formed on the front end side of the sleeve 110. Here, the outlet G2 may discharge the hydraulic oil flowing through the inlet G1 formed in the valve seat 111 to the outside when the poppet 130 to be described later retreats. Hereinafter, forward is defined as moving in the shear direction, and retreat is defined as moving in the rear direction.

The valve seat 111 is connected to the hydraulic device 10 described above, and the hydraulic oil inside the hydraulic device 10 is introduced through the inlet G1, so that the poppet 130 retreats due to the overpressure inside the hydraulic device 10. When the hydraulic oil flows to the rear end portion can be discharged to the outlet (G2) formed on the side of the sleeve (110).

The plug 120 is configured to seal the rear end of the hollow sleeve 110, and may be combined in a form fitted to the rear end of the sleeve 110. The plug 120 may have a space in which the shock absorbing piston 160 to be described later is accommodated. In this embodiment, the shape and coupling structure of the sleeve 110 and the plug 120 are exemplary, and the present invention is not limited thereto. The sleeve 110 and the plug 120 are joined to each other by a threaded coupling or a flange structure between fastening members (not shown) such as bolts/nuts, joints, and/or clamps, or to maintain mechanical bonding strength, or , It may require a sealing member (not shown) for maintaining airtightness.

The poppet 130 is movably installed inside the sleeve 110 to open and close the flow path between the inlet G1 and the outlet G2. Specifically, the poppet 130 is inserted into the sleeve 110 in the longitudinal direction, the front end faces the inlet G1 of the valve seat 111, and the rear end faces the inner piston 150, which will be described later. The front end of the poppet 130 may have a tapered conical shape, and the rear end may have a structure in which the piston 140a is slidable.

The poppet 130 is formed to penetrate the interior from a point openly formed in the front end to an arbitrary point in the rear end direction, and a hollow portion 131 formed to allow hydraulic fluid to flow, and the hollow portion 131 and the first to be described later. A poppet flow path 133 communicating with the chamber CB1 may be provided. Here, the poppet flow path 133 is composed of an orifice having a small cross-sectional area so that the flow of hydraulic oil is slowed down. However, the shapes of the illustrated hollow portion 131 and the poppet flow path 133 are exemplary, and the present invention is not limited thereto.

The poppet 130 may prevent or increase excessive pressure of the hydraulic system 10 by supplying or blocking hydraulic oil to the outlet G2 according to the hydraulic oil pressure of the inlet G1. Specifically, when the hydraulic oil pressure of the inlet G1 rises, the poppet 130 retracts in the direction of the plug 120 to open the flow path between the inlet G1 and the outlet G2, thereby causing the operating oil of the inlet G1 to flow. It should be discharged to the outlet (G2). In addition, the poppet 130 may block the connection between the inlet G1 and the outlet G2 by advancing in the direction of the inlet G1 when the hydraulic oil pressure of the inlet G1 decreases.

The piston 140 is coupled to the rear end of the poppet 130 and can slide in the longitudinal direction of the poppet 130. Specifically, the piston 140 is coupled to the rear end of the poppet 130 in a form in which the poppet 130 is inserted into the hollow shape. At this time, the inside of the piston 140, the poppet 130 is not completely penetrated, but is located only in a part of the area, and in the other remaining areas, an inner piston 150, which will be described later, is inserted to face the rear surface of the poppet 130. That is, the inside of the piston 140 is a structure in which the poppet 130 and the inner piston 150 are inserted in the form facing each other. At this time, the space formed between the poppet 130 and the inner piston 150 is defined as the first chamber CB1.

The stopper 170, which will be described later, is coupled to the outer circumferential surface of the piston 140, and the first elastic member SP1, which will be described later, is supported by the front end of the piston 140, and the rear end of the piston 140 is a flange structure (not shown) Not). The flange structure at the rear end of the piston 140 is in contact with the front end of the plug 120, and when the hydraulic pressure of the second chamber CB2, which will be described later, rises, the flange 140 at the rear end of the piston 140 is pushed out and the piston 140 Advance.

The inner piston 150 faces the poppet 130 and is inserted into the piston 140. As described above, the inner piston 150 is inserted into the rear end of the piston 140 and forms a first chamber CB1 between the poppet 130. When hydraulic oil flows into the first chamber CB1 through the poppet flow path 133 of the poppet 130, the inner chamber 150 is retracted while the first chamber CB1 is expanded. However, the impact relief piston 160 to be described later supports the rear end of the inner piston 150 so that the inner piston 150 does not deviate from the piston 140. When the shock relief piston 160 is advanced by the pressure difference, the inner piston 150 is pushed forward. The rear end of the inner piston 150 may have a stepped structure in which the advance is limited by the piston 140.

The space formed between the inner piston 150 and the sleeve 110 is defined as the second chamber CB2. Specifically, the second chamber CB2 is a space formed between the inner circumferential surface of the sleeve 110 and the internal components of the sleeve 110. That is, the second chamber CB2 is a space where hydraulic oil flows outside the piston 140, the inner piston 150, the shock-absorbing piston 160, and the stopper 170. However, although the second chamber CB2 is minimized in FIG. 3, the size and shape of the second chamber CB2 may be fluidly modified according to the operating state of the hydraulic valve 100.

In addition, the inner piston 150 includes a first flow path H1 communicating the first chamber CB1 and the second chamber CB2. Here, the first flow path H1 may be configured as an orifice having a small cross-sectional area so that the flow of hydraulic oil is slowed down.

Specifically, the first flow path (H1) is connected to the second chamber (CB2) through the side surface of the inner piston 150, the first by the relative movement with the piston 140 covering the side surface of the inner piston 150 The flow path H1 may be opened and closed. That is, as illustrated in FIG. 3, the first flow path H1 is closed by the piston 140 before the hydraulic oil pressure is transmitted. However, the first flow path H1 is opened when the inner piston 150 is retracted while the first chamber CB1 is extended due to the hydraulic oil pressure being transmitted. Alternatively, when the piston 140 moves forward while the second chamber CB2 is expanded, the first flow path H1 may be opened.

The shock absorbing piston 160 is installed in the plug 120 while supporting the rear end of the inner piston 150. The front end of the shock relief piston 160 is in contact with the inner piston 150, and the rear end of the piston 160 may be spaced apart from the plug 120 while being supported by the second elastic member SP2, which will be described later.

The space formed between the plug 120 and the shock-absorbing piston 160 is defined as a third chamber CB3. That is, the third chamber CB3 is a space formed between the inner circumferential surface of the plug 120 and the rear outer circumferential surface of the shock-absorbing piston 160, and may have an approximately'c' shape as illustrated in FIG. 3.

In addition, the shock-absorbing piston 160 includes a second flow path H2 communicating the second chamber CB2 and the third chamber CB3. The second flow path H2 may be provided at a stepped portion (not shown) located at the front end of the shock-absorbing piston 160. Here, the second flow path H2 may be configured as an orifice having a small cross-sectional area so that the flow of hydraulic oil is slowed down.

When the inner piston 150 is retracted, the impact relief piston 160 supporting it is also retracted. When the impact relief piston 160 is retracted, the working oil in the third chamber CB3 is discharged through the second flow path H2 to the second chamber CB2. Conversely, when the shock-absorbing piston 160 is advanced by the elastic restoring force of the second elastic member SP2, the working oil of the second chamber CB2 is introduced into the third chamber CB3 through the second flow path H2. Can.

The stopper 170 is provided between the sleeve 110 and the piston 140 to limit sliding of the piston 140. Specifically, the stopper 170 is inserted and coupled to the piston 140 in a form surrounding the outer circumferential surface of the piston 140, and the rear end of the stopper 170 is supported by contacting the flange structure of the rear end of the piston 140. The rear end of the stopper 170 may be a flange structure (not shown) as the rear end of the piston 140, and the flange structure of the rear end of the stopper 170 is limited in advance by the locking jaw of the inner circumferential surface of the sleeve 110. Conversely, the flange structure at the rear end of the piston 140 is restricted to the retraction by being caught at the front end of the plug 120. That is, the piston 140 and the stopper 170 move together, but the forward and backward movements are limited by the stepped structure of the sleeve 110 and the plug 120.

On the other hand, the hydraulic valve 100 of this embodiment is a first elastic member (SP1) for elastically supporting between the poppet 130 and the piston 140, and the impact relief piston 160 and the plug 120 is burnt A second elastic member SP2 for sexually supporting may be further included. Here, the first elastic member SP1 and the second elastic member SP2 may be springs.

The first elastic member SP1 has one side in contact with a protruding portion (not shown) protruding from the outer circumferential surface of the poppet 130, and the other side in contact with a stepped portion (not shown) of the piston 140, and the pressure of the hydraulic fluid. Due to the relative movement of the poppet 130 and the piston 140 by compression or may be restored.

The second elastic member SP2 has one side in contact with the stepped portion (not shown) of the shock-absorbing piston 160, the other side is in contact with the inner surface of the plug 120, and is compressed due to the movement of the shock-absorbing piston 160 Or can be restored.

4 to 6 are views for explaining the operation of the hydraulic valve of Figure 3, Figure 7 is a graph for explaining the pressure change of the hydraulic valve according to an embodiment of the present invention.

Hereinafter, the operation of the hydraulic valve 100 will be described.

First, it is assumed that the hydraulic valve 100 shown in FIG. 3 is in an initial state, and the pressure change of the hydraulic valve 100 will be described based on the hydraulic pressure of the front end of the poppet 130 adjacent to the inlet G1.

Referring to FIGS. 4 and 7, when the pressure of the hydraulic oil in the front end of the poppet 130 increases during the first section t1, due to this pressure, the first chamber through the hollow portion 131 and the poppet flow path 133 CB1) flows the hydraulic oil. In addition, when the first chamber CB1 is extended during the second section t2, the inner piston 150 and the shock absorbing piston 160 supporting the inner piston 150 retreat, and the shock absorbing piston 160 is When retracted, the second elastic member SP2 is compressed.

Specifically, since the first flow path H1 of the inner piston 150 is blocked by the piston 140, the hydraulic fluid pushes the inner piston 150 until the first flow path H1 overlaps the end of the piston 140. do. At this time, since the third chamber CB3 located at the rear end of the shock absorbing piston 160 is a closed space, hydraulic oil in the third chamber CB3 may be discharged to move the shock absorbing piston 160.

The hydraulic oil in the third chamber H3 is discharged through the second flow path H2 of the shock-absorbing piston 160, and the second flow path H2 is an orifice structure having a small cross-sectional area, so that the hydraulic oil is discharged at a slow speed. During this discharge time, the pressure of the front end of the poppet 130 is no longer raised and remains constant.

Then, when the inner piston 150 is continuously retracted and the first flow path H1 is opened, hydraulic oil flows into the second chamber CB2. That is, when the first flow path H1 of the inner piston 150 passes through the end of the piston 140 and communicates with the second chamber CB2, the inner piston 150 stops moving and the first flow path HB of the first chamber CB1. The hydraulic oil flows into the second chamber CB2. At this time, the front pressure of the poppet 130 and the pressure of the third chamber CB3 at the rear end of the shock relief piston 160 are the same and are maintained constant.

As described above, the working oil flows slowly by the first flow path H1 and the second flow path H2, and the time for which the pressure is kept constant increases.

Next, referring to FIGS. 5 and 7, the inner piston 150 and the shock-absorbing piston 160 by the elastic force of the second elastic member SP2 and the expansion of the second chamber CB2 during the third section t3 ) Is advanced, the piston 140 is advanced and the first elastic member SP1 is compressed. At this time, when the inner piston 150 and the shock-absorbing piston 160 try to move forward by the elastic force of the compressed second elastic member SP2, the working oil of the first oil passage H1 and the second oil passage H2 is applied. The flow is obstructed and moves slowly.

Then, the working oil slowly introduced into the second chamber CB2 expands the second chamber CB2 and slowly compresses the first elastic member SP1 while simultaneously advancing the piston 140 and the stopper 170. As a result, the pressure of the front end of the poppet 130 is gradually increased to the second level.

Next, referring to FIGS. 6 and 7, the poppet 130 retracts due to the pressure at the front end of the poppet 130 during the fourth section t4, and the flow path between the inlet G1 and the outlet G2 is opened. Pressure is released. That is, when the piston 140 and the stopper 170 advance and the pressure rises and reaches a preset pressure, the piston 140 and the stopper 170 stop moving, and finally the poppet 130 retreats, thereby popping ( 130) As the flow path opens at the front end, the hydraulic oil is discharged through the outlet (G2).

In this way, the hydraulic valve 100 and the working machine 1 including the hydraulic valve 100 according to the present invention, the inner piston 150 having an orifice structure at the rear end of the piston 140 of the hydraulic valve 100 and the shock relief piston 160 By further constructing ), the pressure rise becomes slower and the pressure holding time becomes longer, so that the operating shock of the hydraulic valve 100 can be improved.

The present invention has been described in detail through specific examples, but it is for the purpose of specifically describing the present invention, and the present invention is not limited to this, and by those skilled in the art within the technical spirit of the present invention. It will be apparent that the modification or improvement is possible.

All simple modifications or changes of the present invention belong to the scope of the present invention, and the specific protection scope of the present invention will be clarified by the appended claims.

1: Excavator 10: Hydraulic system
100: hydraulic valve 200: casing
300: shaft 400: swash plate
500: piston assay 600: cylinder block
700: valve plate
110: sleeve 111: valve seat
G1: Inlet G2: Outlet
120: plug 130: poppet
131: hollow 133: poppet euro
140: piston 150: inner piston
160: shock absorbing piston 170: stopper
H1: First flow path H2: Second flow path
CB1: First chamber CB2: Second chamber
CB3: Third chamber SP1: First elastic member
SP2: Second elastic member

Claims (9)

A sleeve including an inlet through which hydraulic oil flows and an outlet through which the hydraulic oil is discharged;
A plug sealing the rear end of the sleeve;
A poppet movably installed inside the sleeve to open and close a flow path between the inlet and the outlet;
A piston coupled to the rear end of the poppet and sliding in the longitudinal direction of the poppet;
An inner piston facing the poppet and inserted into the piston;
A first chamber formed between the poppet and the inner piston;
A second chamber formed between the sleeve and the inner piston;
A shock absorbing piston installed in the plug while supporting the rear end of the inner piston; And
It includes a third chamber formed between the plug and the shock absorbing piston,
The inner piston includes a first flow path communicating the first chamber and the second chamber,
The impact relief piston is a hydraulic valve, characterized in that it comprises a second flow path communicating the second chamber and the third chamber. According to claim 1,
The first flow path is connected to the second chamber through the side surface of the inner piston,
The hydraulic valve, characterized in that the first flow path is opened and closed by the relative movement with the piston that covers the side surface of the inner piston. According to claim 2,
A first elastic member elastically supporting between the poppet and the piston,
And a second elastic member elastically supporting the shock-absorbing piston and the plug. The method of claim 3,
When the inner piston and the shock-releasing piston retreat due to the pressure increase of the hydraulic oil, the second elastic member is compressed, the first flow path is opened, and the hydraulic valve is characterized in that the hydraulic oil flows into the second chamber . The method of claim 4,
When the inner piston and the shock-absorbing piston are advanced by the elastic force of the second elastic member and the expansion of the second chamber, the hydraulic valve characterized in that the piston is advanced and the first elastic member is compressed. The method of claim 5,
When the first elastic member is compressed, the hydraulic valve, characterized in that the poppet is retracted due to the pressure rise at the front end of the poppet and the flow path between the inlet and the outlet is opened. According to claim 1,
And a stopper provided between the sleeve and the piston to limit sliding of the piston. The method of claim 1, wherein the poppet,
And a hollow portion connected to the inlet,
A hydraulic valve, characterized in that it has a poppet flow path communicating with the hollow portion and the first chamber. A working machine characterized by having the hydraulic valve according to any one of claims 1 to 8.

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