JP2002130204A - Relief valve unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance workability of assembling and to form overall relief valve unit small and compact by reducing the number of parts in the relief valve unit. SOLUTION: This relief valve device comprises a valve casing 12 and a valve assembly 17. The valve assembly 17 can be preliminarily assembled with a guide sleeve 18, valve sheet members 22A, 22B, a cover body 24, valve bodies 26A, 26B, a valve spring 30, and an accumulator 31, etc. The accumulator, comprising a free piston 32 and accumulating oil chambers 33A, 33B, is set between the left valve body 26A and the right valve body 26B in the guide sleeve 18. Accordingly, the so-called shockless function is given, by opening the valve bodies 26A and 26B at two steps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relief valve device suitably used for an inertial body driving hydraulic circuit provided in a construction machine such as a hydraulic shovel.

[0002]

2. Description of the Related Art In general, construction machines such as hydraulic shovels and hydraulic cranes are provided with a hydraulic circuit for driving an inertial body for traveling or turning, and the hydraulic circuit includes a relief including a pair of cross overload relief valves and the like. A valve device is provided (for example, Japanese Utility Model Laid-Open No. 1-98975).

A conventional relief valve device of this kind is provided with a pair of supply / discharge passages for supplying / discharging pressure oil to / from a hydraulic actuator such as a traveling hydraulic motor, and is provided independently between the pair of supply / discharge passages. And a pair of cross overload relief valves that open when an excess pressure is generated in one of the supply / discharge passages and release the excess pressure to the other supply / discharge passage.

In a traveling hydraulic circuit such as a hydraulic shovel provided with such a relief valve device, a pair of supply / discharge is performed by inertial rotation of a traveling hydraulic motor when a traveling vehicle is stopped. A brake pressure is generated in one of the passages. When the brake pressure becomes excessive and rises to the relief set pressure of the relief valve, the relief valve provided on one of the supply / discharge passages opens, and the excess pressure at this time is supplied to the other supply / discharge passage. And what to miss.

In this case, the kinetic energy of the excessively generated brake pressure generated on one of the supply / discharge passages side is converted into thermal energy while passing through the valve seat member or the like of the opened relief valve. As a result, the inertial force of the vehicle is gradually absorbed, and a braking force is applied to the vehicle.

[0006] When the vehicle is suddenly stopped, an impact or the like may be generated by opening the relief valve. There is a possibility that the life of the relief valve device or the like may be shortened.

Therefore, in the relief valve device according to the prior art, in order to prevent such an impact, the above-mentioned pair of relief valves are provided with a relief valve having a shockless mechanism provided with a main valve element, an auxiliary valve element, a piston and the like. Is adopted.

[0008]

The above-described prior art relief valve device has a structure in which a pair of relief valves which operate independently of each other are provided separately between a pair of supply / discharge passages. There is a tendency that the number of points tends to increase, and not only the entire device becomes large, but also that the workability during assembly cannot be improved.

In the prior art, a relief valve having a shockless function including a main valve element, a sub-valve element, a piston, and the like is used in order to reduce an impact when the relief valve is opened when the vehicle is suddenly stopped. As a result, the number of parts further increases, and there is a problem that it is unavoidable that the whole relief valve device becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. It is an object of the present invention to reduce the number of parts and improve the workability during assembly, and to reduce the size and size of the entire apparatus. To provide a relief valve device.

Another object of the present invention is to provide a shockless function that can reliably reduce an impact when an inertial body such as a vehicle is stopped, and does not increase the number of parts or the like. To provide a relief valve device.

[0012]

In order to solve the above-mentioned problems, a relief valve device according to the present invention is provided with first and second supply / discharge passages for supplying / discharging pressure oil to / from a hydraulic actuator. A valve casing, a cylindrical valve body guide provided between the first and second supply / discharge passages and provided in the valve casing, and having a valve body sliding hole on both axial sides; First and second valve seat members located between the guide and the first and second supply / discharge passages and disposed opposite to both axial ends of the valve body guide; A communication passage formed between the valve seat guide members and the valve casing, the communication passage communicating between the first and second valve seat members on the outer peripheral side of the valve guide; Are respectively inserted into the valve body sliding holes of the valve body guide to communicate with and block the first and second supply / discharge passages. A first and a second valve body which are detachably seated on the first and the second valve seat members, and are formed in the valve body guide between the first and the second valve bodies; A spring chamber communicating with the communication passage, the spring chamber being disposed in the spring chamber;
The second valve body is constituted by a biasing means for setting a relief pressure, which constantly biases the second valve body toward the first and second valve seat members.

[0013] With this configuration, when the hydraulic actuator is stopped or the like, the first and second supply / discharge passages can be removed.
When brake pressure is generated on either of the supply / discharge passages,
Due to this brake pressure, one of the valve bodies separates from the valve seat member against the urging means, and one of the supply / discharge passages communicates with the communication passage via the valve seat member or the like. Then, the brake pressure flows into the other supply / discharge passage or the low-pressure tank by being guided into the communication passage, so that the high-pressure brake pressure can be relieved toward the low-pressure passage.

According to a second aspect of the present invention, in the valve body guide, the first and second valve bodies are positioned between the first and second valve bodies so as to be lower than the relief set pressure by the urging means. An accumulator for temporarily providing a low pressure relief at a low pressure is provided.

Thus, the accumulator can be connected to the first and second accumulators.
And the first and second valve bodies can be temporarily relieved to a low pressure at a pressure lower than the relief pressure set by the urging means, thereby exhibiting a shockless function.

Further, according to the third aspect of the present invention, the first and second valve bodies have piston sliding holes formed on the inner peripheral side thereof, the piston sliding holes communicating with the first and second supply / discharge passages via the throttle passages. The accumulator extends in the axial direction in the spring chamber and both ends are inserted into the piston sliding holes of the first and second valve bodies so as to be slidable in the axial direction. A first piston and a second oil reservoir containing a free piston and pressure oil defined in each of the piston sliding holes by the free piston and guided from the first and second supply / discharge passages through the throttle passage; And a room.

Accordingly, when the pressure oil from the supply / discharge passage flows into the oil storage chamber through the throttle passage, the free piston is displaced so as to retreat in the piston sliding hole of the valve body, and accordingly, the oil storage The indoor volume increases. Accordingly, the pressure in the oil storage chamber temporarily decreases, so that the valve body can be opened at a pressure lower than the relief setting pressure by the urging means, and low-pressure relief can be performed. When the oil storage chamber is completely filled with the pressure oil, the pressure in the oil storage chamber increases accordingly, and at the stage when the pressure in the supply / discharge passage increases to the relief set pressure of the urging means, The valve can be opened to relieve this excess pressure.

According to the fourth aspect of the present invention, the free piston includes a first piston member having one end inserted into the piston sliding hole of the first valve body and the other end extending axially in the spring chamber. , One end of which is in contact with the other end of the first piston member, and the other end of which is inserted into the piston sliding hole of the second valve body.

As a result, the free piston is moved between the first and second
Even if the axial center shift occurs between the first and second valve bodies (piston sliding holes) provided in the valve body guide, this can be divided into the first and second piston members. It can be absorbed between members.

According to the fifth aspect of the present invention, the valve body has a pressure receiving area for receiving the pressure in the supply / discharge passage through the valve seat hole of the valve seat member larger than the pressure receiving area in the oil storage chamber. The valve opening pressure of the valve body is set based on the pressure receiving area difference between the two and the urging force of the urging means.

Thus, even if the urging force of the urging means is reduced, the valve body can reduce the valve opening pressure to a high pressure by reducing the difference between the pressure receiving area on the valve seat hole side and the pressure receiving area in the oil storage chamber. Can be set,
When the pressure receiving area difference is increased, the valve opening pressure can be reduced.

According to a sixth aspect of the present invention, between the first and second supply / discharge passages and the communication passage, the oil in the communication passage is allowed to flow toward the supply / discharge passage. , And a check valve for preventing reverse flow is provided.

Thus, when the pressure of the supply / discharge passage becomes lower than that of the inside of the communication passage, the check valve is opened to supply oil to the low pressure supply / discharge passage side, and the low pressure supply / discharge passage side has a negative pressure. The state can be prevented.

Further, according to the invention of claim 7, the communication passage is connected to the tank. Thereby, when the valve element is opened, the oil liquid can be discharged from the communication passage toward the tank, and when the pressure in the communication passage decreases, the hydraulic oil in the tank can be supplied to the communication passage side.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a relief valve device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking an example in which the relief valve device is applied to a traveling hydraulic circuit such as a hydraulic shovel.

In FIG. 1, reference numeral 1 denotes a hydraulic pump which constitutes a hydraulic source together with a tank 2. The hydraulic pump 1 is driven to rotate by a prime mover (not shown) of a hydraulic shovel and pressurizes hydraulic oil sucked from the tank 2 to a high pressure. Is supplied to a hydraulic motor 3 and the like, which will be described later.

Reference numeral 3 denotes a traveling hydraulic motor which constitutes a hydraulic actuator. The hydraulic motor 3 comprises a pair of main pipelines 4A,
4B and a hydraulic pump 1 via a directional control valve 5 described later.
And the tank 2. And the hydraulic motor 3
Is driven to rotate in the directions indicated by arrows A and B in FIG. 1 by supplying and discharging pressure oil from the hydraulic pump 1 through the main pipelines 4A and 4B, thereby moving the hydraulic shovel (vehicle) forward and backward. It is.

Reference numeral 5 denotes a traveling direction control valve provided in the middle of the main pipelines 4A and 4B. The direction control valve 5 is constituted as an open center type direction control valve having, for example, four ports and three positions as shown in FIG. Then, the operator of the hydraulic excavator performs the tilting operation of the operation lever 5A, thereby switching from the neutral position (A) to the switching positions (B) and (C).

Then, the directional control valve 5 supplies the hydraulic oil from the hydraulic pump 1 to the hydraulic motor 3 via the main pipeline 4A at the switching position (b), and rotates the hydraulic motor 3 in the direction of arrow A, The return oil from the hydraulic motor 3 is discharged to the tank 2 via the main line 4B. When the direction control valve 5 is switched to the switching position (C), the supply direction of the pressure oil is reversed, and the hydraulic motor 3 is rotationally driven in the direction indicated by the arrow B.

Reference numeral 6 denotes a brake valve attached to the hydraulic motor 3. The brake valve 6 is a counterbalance provided between the hydraulic motor 3 and the direction control valve 5 and provided in the main pipelines 4A and 4B. It comprises a valve 7 and a relief valve device 11 described later provided between the counter balance valve 7 and the hydraulic motor 3 and provided in the middle of the main pipelines 4A and 4B.

The counter balance valve 7 switches from the neutral position (a) to the switching positions (b) and (c) almost in conjunction with the direction control valve 5, and the hydraulic oil from the hydraulic pump 1 To compensate for the supply and discharge of Further, the counter balance valve 7 returns to the neutral position (A) when the hydraulic motor 3 rotates by inertia or the like, and the brake pressure is applied between the hydraulic motor 3 and the counter balance valve 7 in the main pipeline 4A or 4B as described later. Is generated.

Reference numerals 8A and 8B denote first and second check valves which constitute a part of the brake valve 6, and the check valves 8A and 8B
Is provided in the middle of the supply pipes 9A and 9B connecting a tank pipe 34 described later to the supply / discharge passages 13A and 13B.
The check valves 8A and 8B are connected to a communication passage 2 described later.
5. The oil liquid in the tank conduit 34 is supplied to the supply / discharge passages 13A, 13B.
It allows flow to the side and prevents reverse flow.

Reference numeral 11 denotes a relief valve device as an overload relief valve which constitutes the brake valve 6 together with the counterbalance valve 7. The relief valve device 11 includes a valve casing 12 as shown in FIG. ,
It is composed of valve bodies 26A and 26B, a valve spring 30, an accumulator 31, and the like. In addition, the valve casing 1
Numeral 2 is usually formed integrally with the motor housing of the hydraulic motor 3 and also serves as a casing of the counterbalance valve 7.

Reference numerals 13A and 13B denote first and second supply / discharge passages formed in the valve casing 12, respectively.
3B constitutes a part of the main pipelines 4A and 4B, and the hydraulic pump 1
Is supplied to and discharged from the hydraulic motor 3.

Numeral 14 denotes a valve receiving hole formed in the valve casing 12. The valve receiving hole 14 is formed as a stepped hole extending between the supply and discharge passages 13A and 13B in the left and right directions as shown in FIG. One end thereof is a small-diameter fitting hole portion 14A and is always in communication with the supply / discharge passage 13A. Also, valve accommodation hole 1
The other end of 4 is a large-diameter screw hole 14B opening to the outside of the valve casing 12, and is always in communication with the supply / discharge passage 13B at the position of the annular oil groove 15 near the screw hole 14B. It is.

Reference numeral 16 denotes a bore formed in the valve casing 12 by cutting out the peripheral wall of the valve housing hole 14. The bore 16 has a length corresponding to a guide sleeve 18 described later. In the axial direction of the valve receiving hole 14.
Is provided between the fitting hole 14 </ b> A and the oil groove 15.
The bore 16 forms a part of a communication passage 25 to be described later.

Reference numeral 17 denotes a valve assembly provided in the valve receiving hole 14. The valve assembly 17 includes a guide sleeve 18 described later,
Valve seat members 22A, 22B, lid 24, valve bodies 26A, 26
B and an assembly composed of the valve spring 30 and the like. The valve assembly 17 is provided with the guide sleeve 18, the valve seat members 22A and 22B, the lid 24, the valve bodies 26A and 26B, etc. integrally assembled as described later, and the fitting hole from the screw hole 14B side. It is inserted into the valve housing hole 14 toward the 14A side.

That is, as shown in FIG. 2, the valve assembly 17 includes the valve bodies 26A and 26B and the valve spring 3 in the guide sleeve 18.
0 and the accumulator 31 and the like to be described later are assembled, and the valve seat members 22A and 22B and the lid 2
A single assembly is constructed by attaching the members 4 by means such as fitting.

The valve assembly 1 thus assembled
7 is the valve seat member 2 in the valve accommodation hole 14 of the valve casing 12.
2A, and inserts the valve seat member 22A into the valve receiving hole 14A.
The cover 24 is fitted into the fitting hole 14A on the back side of the screw hole 14B and the screw hole 14B on the opening end side of the valve accommodating hole 14.
Is assembled into the valve casing 12 by screwing. Thereby, the valve assembly 17 constitutes the relief valve device 11 together with the valve casing 12.

Reference numeral 18 denotes a guide sleeve constituting a stepped cylindrical valve body guide removably inserted into the valve accommodating hole 14. The guide sleeve 18 has an inner periphery on both ends in the axial direction which slides the valve body. Holes 19A, 19B are provided, and the valve body sliding holes 19A, 1B are provided.
Valve bodies 26A and 26B described later are inserted into 9B.

Reference numerals 20A and 20B denote radial oil holes formed at both ends of the guide sleeve 18, respectively.
20B is a valve body sliding hole 19A, 1 of the guide sleeve 18.
The inside of 9B is communicated with the inside of the boring groove 16 to thereby form a communication passage 25 described later. A radial oil hole 21 for communicating a spring chamber 29 to be described later with the communication passage 25 is formed in an axial middle portion of the guide sleeve 18.

Reference numerals 22A and 22B denote valve seat members as first and second valve seat members fitted and attached to both axial ends of the guide sleeve 18, respectively.
As shown in FIG. 3, it is formed as a stepped cylindrical body, and its inner peripheral side has valve seat holes 23A and 23B having an inner diameter of dimension D1. The valve seat members 22A and 22B are disposed on both sides of the guide sleeve 18 in the axial direction so as to face each other.
A, 23B are provided with valve bodies 26A, 26B for supply / discharge passages 13A,
The seat is separated and seated according to the pressure in 13B.

Here, the left valve seat member 22A shown in FIG.
Is detachably fitted in the fitting hole portion 14A on the back side of the valve housing hole 14, and the valve seat hole 23A is always in communication with the supply / discharge passage 13A. The right valve seat member 22B is a cover 2
4, the lid 24 is screwed into the screw hole 14B of the valve receiving hole 14 from the outside.

Thus, the valve assembly 17 including the valve seat members 22A and 22B, the guide sleeve 18, and the like is fixed in the valve receiving hole 14 in a fitted state. And
At this time, the lid 24 closes the screw hole 14B serving as the opening end of the valve housing hole 14, and the valve seat hole 23B of the valve seat member 22B.
Is always in communication with the supply / discharge passage 13B via the oil groove 15 or the like.

Reference numeral 25 denotes a communication passage which communicates between the valve seat holes 23A and 23B of the valve seat members 22A and 22B on the outer peripheral side of the guide sleeve 18. The communication passage 25 is an oil hole of the bore 16 and the guide sleeve 18. 20A and 20B. The communication passage 25 is provided in the guide sleeve 1.
The inside of the oil holes 20A and 20B located at both ends of the nozzle 8 is always kept at the same pressure.

Reference numerals 26A and 26B denote first and second valve bodies provided in the guide sleeve 18, respectively.
Consists of a cylindrical poppet valve body with the same shape as each other,
The guide sleeve 18 is slidably inserted into the valve body sliding holes 19A and 19B.

The valve bodies 26A, 26B receive the pressure from the supply / discharge passages 13A, 13B through the valve seat holes 23A, 23B of the valve seat members 22A, 22B. , 22B valve seat hole 23
A and 23B, the communication passage 25 is connected to the supply / discharge passage 13.
A and 13B are communicated and blocked.

Further, on the inner peripheral side of the valve bodies 26A and 26B,
Orifices 27A, 27B as throttle passages which are always in communication with the supply / discharge passages 13A, 13B;
Piston sliding holes 28A and 28B are formed, which communicate with the supply / discharge passages 13A and 13B via 27B and into which piston members 32A and 32B described later are inserted.

The piston sliding holes 28A and 28B constitute a part of an accumulator 31 described later, and the diameter of the piston sliding holes 28A and 28B is equal to the diameter of the valve seat holes 23A and 23B as shown in FIG. Dimension D smaller in diameter than (dimension D1)
2 (D2 <D1).

Reference numeral 29 denotes a spring chamber formed between the valve bodies 26A and 26B and formed on the inner peripheral side of the guide sleeve 18. Reference numeral 30 denotes a biasing means disposed in the spring chamber 29 in a contracted state. FIG. 3 shows a valve spring for setting a relief pressure;
Is composed of a single coil spring or the like having a biasing force F1, and the valve bodies 26A and 26B are connected to the valve seat member 22 at both ends.
A and 22B are always biased toward the valve seat holes 23A and 23B.

An accumulator 31 is provided between the valve bodies 26A and 26B and provided in the guide sleeve 18. The accumulator 31 is composed of a free piston 32 and oil storage chambers 33A and 33B, which will be described later. 26A, 26
The pressure B is temporarily reduced to a low pressure by a pressure Pa (see FIG. 5) lower than a relief set pressure Pb to be described later by the valve spring 30.

Reference numeral 32 denotes a free piston which constitutes the accumulator 31. The free piston 32 has a piston sliding hole 28 at one end side of the valve body 26A.
A, a first piston member 32A whose other end is axially extended in the spring chamber 29, one end of which is in contact with the other end surface of the piston member 32A, and the other end of which is a valve body 26B.
And a second piston member 32B inserted into the piston sliding hole 28B.

Here, the first and second piston members 32
A, 32B, the total length of the free piston 32 is equal to the length of the first and second valve bodies 26 disposed in the guide sleeve 18.
The piston members 32A, 32B are formed to be axially slidable in the piston sliding holes 28A, 28B by being formed smaller than the distance between the piston sliding holes 28A, 28B due to A, 26B. .

33A and 33B are piston members 32A and 3
The first and second oil storage chambers defined in the piston sliding holes 28A and 28B by 2B, the oil storage chambers 33A and 33B
The supply / discharge passage 13A, 1 is connected via the orifices 27A, 27B.
3B, and the piston members 32A, 32B cause the piston sliding holes 28A, 28B
Is to be slid and displaced in the axial direction.

That is, the free piston 32 is connected to the supply / discharge passage 13.
A and 13B, for example, when a high brake pressure is generated on the supply / discharge passage 13B side, the piston slide hole 28B is displaced from the piston slide hole 28B side to the piston slide hole 28A side. The volume in the oil storage chamber 33B is increased on the side, and the volume in the oil storage chamber 33B is reduced. When a high brake pressure is generated on the supply / discharge passage 13A side,
The free piston 32 is displaced in the opposite direction, the volume in the oil storage chamber 33A is increased, and the volume on the oil storage chamber 33A side is reduced.

A tank line 34 communicates with the communication passage 25 of the relief valve device 11.
Connects the communication passage 25 to the tank 2 as shown in FIG.
The inside of the communication passage 25 of the relief valve device 11 is always kept at the tank pressure.

The traveling hydraulic circuit of the hydraulic excavator provided with the relief valve device 11 according to the present embodiment has the above-described configuration. Next, the operation thereof will be described.

First, when the operator of the excavator switches the directional control valve 5 shown in FIG. 1 from the neutral position (a) to the switching position (b) in order to drive the vehicle, the hydraulic oil from the hydraulic pump 1 The oil is supplied to the hydraulic motor 3 from the side of the main pipeline 4A (the supply / discharge passage 13A). Then, at this time, the counterbalance valve 7 switches from the neutral position (a) to the switching position (b) due to the differential pressure between the supply / discharge passages 13A and 13B, and returns oil from the hydraulic motor 3 via the counterbalance valve 7. Then, the water is discharged from the main pipeline 4B (supply / discharge passage 13B) to the tank 2.

On the other hand, in order to stop the vehicle, the operator moves the direction control valve 5 from the switching position (b) to the neutral position (b).
In this case, the pressure on the side of the main conduit 4A (the supply / discharge passage 13A) decreases to the tank pressure level. As a result, the counterbalance valve 7 returns to the neutral position (A) with the pressure drop on the supply / discharge passage 13A side, and the supply / discharge passages 13A, 13B
Is prevented (blocked) from flowing from the hydraulic motor 3 to the hydraulic pump 1 and the tank 2.

In this case, the hydraulic motor 3 often continues to rotate by inertia due to the inertial force during traveling of the vehicle. During this inertial rotation, even after the directional control valve 5 returns to the neutral position (a), the hydraulic motor 3 continues to rotate. A pump action is performed to discharge the pressure oil sucked from the passage 4A to the main pipeline 4B.

Then, a high-pressure brake pressure is generated on the side of the supply / discharge passage 13B by the pump action of the hydraulic motor 3, and this brake pressure is applied from the inside of the valve seat member 22B to the valve body 26B in the direction of arrow C in FIG. Acts toward. For this reason, the valve element 26B
Receives the brake pressure through the valve seat hole 23B of the valve seat member 22B. At this time, when the brake pressure rises to a relief set pressure Pb to be described later, the valve body 26B resists the urging force F1 of the valve spring 30. Open the valve.

When the accumulator 31 is not used, when the vehicle is to be stopped suddenly, for example, the valve body 26B of the relief valve device 11 is moved from the supply / discharge passage 13B side in the direction of arrow C. The high pressure applied to the brake causes the valve to rapidly open as shown by a characteristic line 35 shown by a two-dot chain line in FIG. 5, and a surge may occur in the vehicle due to a surge pressure or the like generated at this time.

Therefore, in the present embodiment, the valve bodies 26A, 26 are provided in the guide sleeve 18 of the relief valve device 11.
6B, an accumulator 31 is provided, and the accumulator 31 causes the valve element 26B (26A) to temporarily move at a pressure Pa lower than the relief set pressure Pb of the valve spring 30, as indicated by a solid line 36 in FIG. A low pressure relief is provided to provide a shockless function to reduce the impact.

That is, a high brake pressure is generated on the side of the supply / discharge passage 13B when the vehicle is stopped or the like, and this brake pressure is applied from the valve seat hole 23B of the valve seat member 22B in the direction of arrow C in FIG. When acting toward 26B, the pressure oil at this time flows into the oil storage chamber 33B of the accumulator 31 through the orifice 27B as shown in FIG.

Then, the pressure oil flowing into the oil storage chamber 33B presses the piston member 32B in the direction of arrow C so that the piston member 32B retreats in the piston sliding hole 28B of the valve body 26B. The oil reservoir 33B is displaced, and accordingly, the volume in the oil storage chamber 33B increases.

As a result, the pressure in the oil storage chamber 33B temporarily drops, and the oil storage chamber 33B presses the valve body 26B in the valve closing direction.
As the pressure in B decreases, the valve body 26B temporarily opens at a pressure Pa lower than the relief set pressure Pb as indicated by a characteristic line 36 shown by a solid line in FIG.

In this case, as shown in the following equations (1) and (2), the valve body 26B has a hole diameter (dimension D1) of the valve seat hole 23B.
), The brake pressure is received in the valve opening direction in the direction indicated by arrow C in the direction indicated by arrow C. In the accumulator chamber 33B, the pressure receiving area S2 determined by the inner diameter D2 is opposite to the direction indicated by arrow C (the valve closing direction). ) Receives the pressure in the oil storage chamber 33B.

[0068]

S1 = D1 ² × π / 4

[0069]

## EQU2 ## S2 = D2 ² × π / 4

However, when the piston member 32B is displaced so as to retreat in the piston sliding hole 28B, the pressure in the oil storage chamber 33B sharply decreases as the volume in the oil storage chamber 33B increases. Therefore, the valve body 26B at this time is
The valve is pressed in the valve opening direction against the valve spring 30 by only the force corresponding to the pressure receiving area S1 in which the brake pressure is received in the valve opening direction on the valve seat member 22B side.

When the brake pressure at this time exceeds the pressure Pa according to the following equation (3), which is lower than the relief set pressure Pb, the valve element 26B resists the urging force F1 of the valve spring 30 as shown in FIG. Thus, the valve can be opened and the low-pressure relief operation for alleviating the impact can be performed.

[0072]

[Equation 3] Pa ≧ F1 / S1

In the state where the valve body 26B performs the low pressure relief by the accumulator 31, the free piston 32 (piston members 32A, 32B) reaches the stroke end as shown in FIG. When the pressure is completely filled, the pressure in the oil storage chamber 33B rises to the same pressure as that in the supply / discharge passage 13B (valve seat member 22B).

When the pressure in the supply / discharge passage 13B rises to the relief set pressure Pb of the valve spring 30,
By the following equation (4), the valve element 26B opens against the urging force F1 of the valve spring 30, and the excess pressure at this time is released to the communication passage 25 and the tank pipe 34 side. High pressure relief operation can be performed.

[0075]

(S1−S2) × Pb ≧ F1

As a result, the kinetic energy of the brake pressure generated on the side of the supply / discharge passage 13B is generated during the passage of the pressure oil at this time between the valve seat hole 23B of the valve seat member 22B and the valve body 26B. It is converted into energy and the vehicle is gradually stopped by the brake pressure at this time.

On the other hand, when the traveling direction control valve 5 is switched from the neutral position (A) to the switching position (C), the motor driving pressure is supplied to the supply / discharge passage 13B side, and the hydraulic motor 3 Is rotationally driven in the direction of arrow B in the opposite direction. Then, when the direction control valve 5 is thereafter returned from the switching position (C) to the neutral position (A), for example, a brake pressure is generated on the side of the supply / discharge passage 13A, and the valve body 26A becomes substantially the same as the above-described case. Similarly, the valve is opened, and the vehicle is gradually stopped by sequentially performing the low-pressure relief operation and the high-pressure relief operation.

Here, the relief set pressure Pb, which is the valve opening pressure of the valve bodies 26A and 26B, is determined by the equation (4) as follows. A pressure receiving area S1 for receiving the pressure in the supply / discharge passages 13A and 13B through the pressure storage areas 23A and 23B, and oil storage chambers 33A and 33.
Is determined by the pressure receiving area difference (S1-S2) from the pressure receiving area S2 and the urging force F1 of the valve spring 30.

For this reason, even if the urging force F1 of the valve spring 30 is reduced, the valve body 26A, 26B has a pressure receiving area difference (S1-S).
If 2) is reduced, the valve opening pressure can be set to a high pressure. Conversely, if the pressure receiving area difference (S1-S2) is increased, the valve opening pressure of the valve bodies 26A and 26B can be reduced.
The valve opening pressure can be adjusted by this pressure receiving area difference (S1-S2).

As shown in FIG. 1, between the first and second supply / discharge passages 13A and 13B and the communication passage 25 and the tank pipe 34, the oil in the communication passage 25 is supplied with the supply / discharge passages 13A and 13A. 13
Check valves 8A and 8B are provided to allow the flow toward B and prevent the flow in the opposite direction.

For this reason, when the pressure of the supply / discharge passage 13A (13B) becomes lower than the inside of the communication passage 25 due to the inertial rotation of the hydraulic motor 3 or the like, the check valve 8A (8B) is opened to supply / discharge the low pressure. The oil liquid can be supplied to the passage 13A (13B) side, and the low pressure supply / discharge passage 13A (13B) side can be prevented from being in a negative pressure state.

Further, since the communication passage 25 is connected to the tank 2 by the tank pipe 34 or the like, the valve 2
When the valve 6A (26B) is opened, the tank 2
The hydraulic fluid in the tank 2 is discharged when the pressure in the communication passage 25 decreases.
5 can be supplied, and the inside of the communication passage 25 can be always maintained in a positive pressure state.

Thus, in the present embodiment, the relief valve device 11 comprises the valve casing 12 and the valve assembly 17, and the valve assembly 17 comprises the guide sleeve 18, the valve seat members 22A and 22B, the lid Body 24, valve bodies 26A and 26B,
The valve spring 30 and the accumulator 31 are preliminarily assembled.

For this reason, the valve assembly 17 is connected to the valve casing 1.
By simply assembling the relief valve device 11 into the second valve housing hole 14, the relief valve device 11 can be easily assembled, the workability at the time of assembly can be greatly improved, and the entire device can be formed compact, resulting in a reduction in size and weight. Can be planned.

The valve assembly 17 includes the guide sleeve 1
In a state where the valve bodies 26A and 26B, the valve spring 30 and the accumulator 31 are incorporated in the valve body 8, the valve seat members 2 are provided at both ends thereof.
By mounting the 2A, 22B and the lid 24 using means such as fitting, a single assembly can be formed, and the pre-assembly work can be easily performed.

Therefore, the troublesome assembling work of separately assembling a pair of relief valve bodies and the like into the valve casing as in the prior art can be omitted, and the assembling work can be performed efficiently. Further, the pair of valve bodies 26A and 26B can be continuously urged in the valve closing direction by the single valve spring 30, and the number of parts can be reliably reduced.

Therefore, according to the present embodiment, the number of components of the relief valve device 11 can be reduced and the workability at the time of assembling can be surely improved, and the entire device can be downsized and formed compact. Operation can be stabilized.

Further, since the urging force of the valve spring 30 can be evenly applied to the left and right valve bodies 26A, 26B, even if the brake pressure is generated in any of the supply / discharge passages 13A, 13B. The valve bodies 26A and 26B can be opened and closed equally on the left and right sides, and the relief performance thereof can easily suppress variation on the left and right sides.
The relief performance by the 26B can be made uniform on the left and right, and the stability and reliability of the relief operation can be reliably improved.

In the guide sleeve 18, a free piston 32 is located between the left and right valve bodies 26A and 26B.
And accumulator 3 composed of oil storage chambers 33A and 33B
1, the valve elements 26A and 26B can be opened in two stages as indicated by a characteristic line 36 shown by a solid line in FIG. 5, and a low-pressure relief operation and a high-pressure relief operation can be performed. A so-called shockless function for reducing the shock at the time can be exhibited.

Further, the free piston 32 of the accumulator 31 is divided into two parts by the first and second piston members 32A and 32B, and the end faces of the two are brought into contact with each other in the spring chamber 29. Guide sleeve 1
8 that slides through the valve body sliding holes 19A and 19B.
Even if the axial center is shifted between A and 26B (piston sliding holes 28A and 28B), the center shift can be absorbed between the piston members 32A and 32B, and the relief valve device 11 (valve assembly 17) can be used. 2) can be improved.

The piston members 32A, 32
B is the supply / discharge passages 13A, 13A together with the valve bodies 26A, 26B.
B, so that the supply / discharge passage 13
The entire free piston 32 (piston members 32A, 32B) is moved in accordance with the pressure difference between the piston sliding holes 2A, 13B.
8A, 28B, the lower pressure supply and discharge passages 13A,
13B can be smoothly slid and displaced to the side of the piston members 32A, 32B when the brake pressure is generated.
The stroke amount of B can be made large, and the impact relaxation action can be reliably exhibited.

In the above embodiment, the main pipeline 4A,
Although the counter balance valve 7 is provided in the middle of 4B, the present invention is not limited to this. For example, the counter balance valve is abolished as in a modification shown in FIG. Directional control valve,
In this case, substantially the same operation and effect as those of the above embodiment can be obtained.

In the above embodiment, the lid 24 is formed integrally with the valve seat member 22B. However, the present invention is not limited to this. For example, the lid 24 may be formed integrally with the valve seat member 22B. Formed as a separate member, the casing body 10
After the valve seat member 22B is inserted into the valve housing hole 14, the lid 24 may be screwed into the screw hole 14B.

Furthermore, in the above-described embodiment, the case where the traveling hydraulic motor 3 is used as the hydraulic actuator has been described as an example. However, the present invention is not limited to this, and for example, a turning hydraulic motor or a rope winch is used. The present invention can also be applied to a hydraulic circuit using a hydraulic motor or the like. The present invention is not limited to a hydraulic excavator, a hydraulic crane, and the like, and can be widely applied to a relief valve device of another construction machine including a traveling or turning hydraulic motor or the like.

[0095]

As described in detail above, according to the first aspect of the present invention, the first and second valve bodies are provided on the valve casing on both sides in the axial direction between the pair of supply / discharge passages. A valve body guide to be inserted, a pair of valve seat members disposed opposite to each other with a valve body interposed therebetween at both axial ends of the valve body guide, and between the respective valve seat members on the outer peripheral side of the valve body guide. And a spring chamber is formed in the valve body guide between the respective valve bodies, and each of the valve bodies is urged toward the valve seat member side in the spring chamber. Since the urging means for setting the relief pressure is provided, the number of parts of the relief valve device can be reduced, the workability at the time of assembly can be improved, and the entire device can be made compact and compact. Further, the urging force of the urging means can be uniformly applied to the first and second valve bodies, so that even if a brake pressure is generated on either of the pair of supply / discharge passages, the left pressure is maintained. , Right and even relief performance can be exerted on the right.

According to the second aspect of the present invention, the first and second valve bodies are located in the valve body guide between the first and second valve bodies.
Since the accumulator for temporarily lowering the second valve body at a pressure lower than the relief set pressure by the urging means is provided, the accumulator can be compactly arranged between the first and second valve bodies. The first and second valve bodies can be temporarily relieved at a low pressure at a pressure lower than the relief set pressure by the urging means. Therefore, without specially increasing the number of parts and the like of the relief valve device,
An impact when stopping an inertial body such as a vehicle can be reliably reduced, and a shockless function can be provided.

Further, according to the third aspect of the present invention, the first and second valve bodies are provided with piston sliding holes communicating with the first and second supply / discharge passages through the throttle passages on the inner peripheral side. The accumulator is formed as a cylindrical poppet valve body, and the accumulator is inserted into the piston sliding holes of the first and second valve bodies so as to be slidable in the axial direction. Since the first and second oil storage chambers defined in the piston sliding hole are formed, when the pressure oil from the supply / discharge passage flows into the oil storage chamber through the throttle passage, the free piston Is displaced so as to retreat in the piston sliding hole, the volume in the oil storage chamber can be increased accordingly, the pressure in the oil storage chamber is temporarily reduced, and the pressure is lower than the relief set pressure by the urging means. With this, the valve can be opened and low pressure relief can be performed. When the oil storage chamber is completely filled with pressure oil, the pressure in the oil storage chamber increases accordingly, and the pressure in the supply / discharge passage rises to the relief set pressure of the urging means. The valve can be opened to relieve excess pressure.

Further, according to the fourth aspect of the invention, the first and second valve bodies (piston slides) provided in the valve body guide are formed by dividing the free piston into first and second piston members. Even if there is a deviation of the axis between
It can be absorbed between the second piston members, and the ease of assembly of the relief valve device can be improved.

According to the fifth aspect of the present invention, the pressure receiving area of the valve body for receiving the pressure in the supply / discharge passage through the valve seat hole of the valve seat member is made larger than the pressure receiving area in the oil storage chamber. Since the valve opening pressure of the valve body is set by the pressure receiving area difference between the two and the biasing force of the biasing means, even if the biasing force of the biasing means is reduced, the valve body is located on the valve seat hole side. By reducing the difference between the pressure receiving area and the pressure receiving area in the oil storage chamber, the valve opening pressure can be set to a high pressure, and when the pressure receiving area difference is increased, the valve opening pressure can be reduced.

Further, according to the present invention, between the first and second supply / discharge passages and the communication passage, the oil in the communication passage flows toward the supply / discharge passage. A check valve is provided to allow the flow in the opposite direction.When the pressure in the supply / discharge passage becomes lower than that in the communication passage, the check valve is opened and the oil is supplied to the low-pressure supply / discharge passage side. The liquid can be replenished and the low pressure supply / discharge passage side can be prevented from being in a negative pressure state.

Further, since the communication passage is connected to the tank according to the present invention, the oil can be discharged from the communication passage toward the tank when the valve body is opened, and the communication passage in the communication passage can be discharged. When the pressure drops, the hydraulic oil in the tank can be supplied to the communication passage side, and the inside of the communication passage can always be maintained at a positive pressure.

[Brief description of the drawings]

FIG. 1 is a traveling hydraulic circuit diagram of a hydraulic shovel to which a relief valve device according to an embodiment of the present invention is applied.

FIG. 2 is a longitudinal sectional view showing the relief valve device in FIG.

FIG. 3 is an enlarged longitudinal sectional view showing a relief valve device in a low-pressure relief state.

FIG. 4 is a longitudinal sectional view substantially similar to FIG. 3, showing a state in which one valve element is opened.

FIG. 5 is a characteristic diagram showing valve opening characteristics of the relief valve device.

FIG. 6 is a traveling hydraulic circuit diagram of a hydraulic shovel to which a relief valve device according to a modification is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic pump 3 Hydraulic motor (hydraulic actuator) 4A, 4B Main pipeline 5, 5 'Direction control valve 8A, 8B Check valve 11 Relief valve device 12 Valve casing 13A, 13B Supply / discharge passage 14 Valve accommodation hole 17 Valve assembly 18 Guide Sleeve (valve guide) 19A, 19B Valve slide hole 20A, 20B Oil hole 21 Oil hole 22A, 22B Valve seat member 23A, 23B Valve seat hole 25 Communication passage 26A, 26B Valve 27A, 27B Orifice (throttle passage) 28A, 28B Piston sliding hole 29 Spring chamber 30 Valve spring (biasing means) 31 Accumulator 32 Free piston 32A, 32B Piston member 33A, 33B Oil storage chamber 34 Tank line

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yoshinori Takeuchi 650, Kandachi-cho, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. 3H059 AA06 BB22 CD05 EE01 FF03 FF14 3H089 AA64 CC08 DA02 DA13 DB04 DB08 DB33 DB46 DB49 DB55 DC02 GG02 HH05 JJ02

Claims (7)

[Claims] A valve casing provided with first and second supply / discharge passages for supplying / discharging pressure oil to / from a hydraulic actuator; and a valve casing located between the first and second supply / discharge passages. A cylindrical valve body guide provided with a valve body sliding hole on both sides in the axial direction; and a shaft of the valve body guide positioned between the valve body guide and the first and second supply / discharge passages. First and second valve seat members opposed to each other at both ends in the direction, formed between the first and second valve seat members on the valve body guide and the valve casing; A communication passage that communicates between the first and second valve seat members on the outer peripheral side of the first and second valve seat members; and a communication passage that communicates with the first and second supply / discharge passages.
First and second valve bodies respectively inserted and fitted into the valve body sliding holes of the valve body guide to shut off, and separated from and seated on the first and second valve seat members; A spring chamber formed in the valve body guide between the valve bodies and communicating with the communication passage; disposed in the spring chamber;
A relief valve device constituted by a biasing means for setting a relief pressure constantly biased toward the second valve seat member. 2. The valve body guide is located between the first and second valve bodies and temporarily operates the first and second valve bodies at a pressure lower than a relief set pressure by the urging means. 2. The relief valve device according to claim 1, wherein an accumulator for performing low pressure relief is provided. 3. A cylindrical poppet, wherein the first and second valve bodies have a piston sliding hole communicating with the first and second supply / discharge passages through a throttle passage on an inner peripheral side. Consisting of a valve body,
The accumulator is a free piston that extends in the axial direction in the spring chamber and has both ends inserted and slidably displaceable in the axial direction in piston sliding holes of the first and second valve bodies. A first and a second oil storage chamber defined in each piston sliding hole and configured to store pressure oil guided from the first and second supply / discharge passages through the throttle passage. 3. The relief valve device according to 2. 4. A first piston member, one end of which is inserted into a piston sliding hole of the first valve body and the other end of which extends axially in the spring chamber; The second piston abuts on the other end side of the piston member and the other end is inserted into the piston sliding hole of the second valve body.
4. The relief valve device according to claim 3, wherein the relief valve device comprises: 5. A pressure receiving area for receiving pressure in a supply / discharge passage through a valve seat hole of the valve seat member is formed larger than a pressure receiving area in the oil storage chamber. 5. The relief valve device according to claim 3, wherein the valve opening pressure of the valve body is set based on the biasing force of the biasing unit. 6. 6. Between the first and second supply / discharge passages and the communication passage, oil in the communication passage is allowed to flow toward the supply / discharge passage, and a reverse flow is provided. 6. The relief valve device according to claim 1, further comprising a check valve for blocking. 7. The relief valve device according to claim 1, wherein the communication passage is configured to be connected to a tank.