JP3336181B2 - Relief valve with accumulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relief valve with an accumulator suitable for use in a hydraulic circuit for driving a hydraulic motor such as a hydraulic shovel.

[0002]

In general, a hydraulic excavator, construction machinery such as a hydraulic crane, traveling by a hydraulic motor as a hydraulic actuator, although turning driven, travel, for receiving excessive inertial load during turning of the stop, the hydraulic circuit , A brake valve using a pair of relief valves with accumulators is interposed, and the brake valve converts the inertial load into heat energy of pressurized oil and absorbs the heat (for example, Japanese Utility Model Application Laid-Open No. 58-33834). Reference).

FIGS. 2 to 4 show an example of a hydraulic motor drive circuit using a conventional relief valve with an accumulator of this type as a brake valve.

In FIG. 1, reference numeral 1 denotes a hydraulic motor as an actuator. The hydraulic motor 1 is constituted, for example, as a radial piston type hydraulic motor, and its inertia body has a reduction gear (both not shown) on its rotating shaft. Are connected via The hydraulic motor 1 has a supply / discharge port connected to a hydraulic pump 3 as a hydraulic source and a tank 4 via a pair of conduits 2A, 2B and the like, respectively. Thus, the hydraulic motor 1 is driven.

[0005] Reference numeral 5 denotes a directional control valve located between the hydraulic motor 1 and the hydraulic pump 3 and provided in the middle of the pipelines 2A and 2B. The directional control valve 5 is set to a neutral position (a) by the driver. Then, the switching operation is performed to the switching positions (b) and (c). At these switching positions (b) and (c), the rotation direction of the hydraulic motor 1 is switched to the directions indicated by arrows F and R in FIG. When the directional control valve 5 returns to the neutral position (a), the hydraulic pump 3 shuts off the supply and discharge of pressure oil from the hydraulic pump 3 to the hydraulic motor 1 and stops the hydraulic motor 1.

Reference numeral 6 denotes a brake valve provided between the hydraulic motor 1 and the direction switching valve 5 and provided in the middle of the pipelines 2A and 2B. The brake valve 6 includes a counter balance valve 10 and a relief valve 10 to be described later. 12A, 12B, etc.
It is provided integrally with a housing (not shown) of the hydraulic motor 1. When the hydraulic motor 1 is rotated by inertia when the direction switching valve 5 returns to the neutral position (a), one of the relief valves 12A and 12B is opened and the brake valve 6 opens the lines 2A and 2B. The pressure oil on the high pressure side is relieved to the low pressure side to apply a braking force to the hydraulic motor 1.

[0007] Reference numerals 7A and 7B denote a pair of oil passages formed in the brake valve 6 and forming a part of the conduits 2A and 2B. It is composed of hydraulic source-side oil passages 8A and 8B connected to the hydraulic pump 3 and the tank 4 via the hydraulic pump 3, and actuator-side oil passages 9A and 9B connected to the hydraulic motor 1.

Reference numeral 10 denotes a counterbalance valve provided between the hydraulic oil passages 8A, 8B and the actuator oil passages 9A, 9B. The counterbalance valve 10 is provided with a pressure guided to pilot pipelines 11A, 11B. Switching from the neutral position (a) to the switching positions (b) and (c) in conjunction with the direction switching valve 5 by the oil pressure .

Reference numerals 12A and 12B denote a pair of relief valves with accumulators (hereinafter referred to as "relief valves 12A and 12B"). The relief valves 12A and 12B are provided in the middle of the actuator-side oil passages 9A and 9B. The relief valves 12A and 12B have stepwise relief characteristics with respect to the pressure of the actuator-side oil passages 9A and 9B as shown in the characteristic diagram of FIG.

Here, the configuration of the relief valve 12A will be described with reference to FIG.

Reference numeral 13 denotes a valve casing fixed to a motor casing (not shown) of the hydraulic motor 1. Inside the valve casing 13, hydraulic pressure source side oil passages 8A and 8 shown in FIG.
B and actuator-side oil passages 9A and 9B are formed.

A housing hole 13A for housing a valve guide 15 described later is formed in the valve casing 13. A stopper 13B is formed on a part of the peripheral surface of the housing hole 13A so as to project radially toward the central axis,
The stopper 13B regulates a stroke end of a piston 24 inserted into an annular space 23 described later.

Reference numeral 14 denotes the actuator-side oil passages 9A, 9
B shows a cylindrical valve seat provided between B. One side of the valve seat 14 is an insertion portion 14A for inserting the valve seat 14 itself between the actuator-side oil passages 9A and 9B in the valve casing 13. A fitting portion 14 on the other side of which a valve guide 15 described later is fitted.
B. An inner peripheral edge located on the other end side of the fitting portion 14B of the valve seat 14 is provided with a relief valve body 18 described later.
Is a valve seat portion 14C for taking off and seating.

Reference numeral 15 denotes a valve guide provided in the valve casing 13. The valve guide 15 has a one-side cylindrical portion 1 whose one end is fitted to an outer peripheral side of a fitting portion 14B of the valve seat 14.
5A, and the other end side is the other-side cylindrical portion 15B that has become a closed end when a lid 17 described later is inserted. The portion of the valve guide 15 closer to one side than the axially intermediate portion is a tapered portion 15C in which the outer diameter of the valve guide 15 gradually decreases from the other side toward one side, and the one side cylindrical portion 15A is The diameter is formed smaller than that of the other cylindrical portion 15B.

The inner peripheral side of the tapered portion 15C of the valve guide 15 is a small-diameter valve element sliding hole 15D, into which a relief valve element 18 described later can slide. It is inserted in.

Further, one side cylindrical portion 15A of the valve guide 15
Are formed with radial holes 15E, 15E,.
An oil chamber 16 located between the relief valve element 18 and the valve seat 14 and formed in one side cylindrical portion 15A of the valve guide 15 is always in communication with the actuator-side oil passage 9B through each of the communication holes 15E. ing.

Reference numeral 17 denotes a cover located at the other end of the valve guide 15 and screwed to the valve casing 13.
Is formed in a bottomed cylindrical shape from a bottom portion 17A and a cylindrical portion 17B, and the bottom portion 17A of the lid 17 closes the other end of the valve guide 15. The other end of the valve guide 15 is inserted into the cylindrical portion 17B of the lid 17, and the valve seat 14 is
At the same time, the valve guide 15 is held in the casing 13.

Further, the cylindrical portion 17B of the lid 17 is formed to be thick, whereby the valve guide 15 is radially separated from the valve casing 13 by the thickness of the cylindrical portion 17B. An annular space 23 described later is formed between the valve guide 15 and the valve casing 13.

Reference numeral 18 denotes a relief valve element which is slidably inserted into a valve element sliding hole 15D of a valve guide 15 so that one end of the relief valve element is detachably seated on the valve seat 14.
Defines a spring chamber 19 in the valve guide 15 at the other end.

Reference numeral 20 denotes a small-diameter orifice formed at one end of the relief valve element 18 in the axial direction.
Reference numeral 0 denotes a communication between the spring chamber 19 and the actuator-side oil passage 9A with a predetermined restriction.

Reference numeral 21 designates a setting spring disposed in the spring chamber 19, which sets the relief valve element 18 to the valve seat 14
, The relief valve element 18 is normally closed, and when the pressure in the actuator-side oil passage 9A reaches a predetermined relief set pressure P1, as shown in FIG. Allows the valve to open.

Reference numeral 22 denotes an accumulator for temporarily reducing the relief valve body 18 to a low pressure at a pressure P2 lower than the relief set pressure P1.
An annular space 23, a piston 24, a communication hole 27, and the like, which will be described later, are provided.

Reference numeral 23 denotes an annular space formed between the valve guide 15 and the valve casing 13. The annular space 23
One end communicates with the actuator-side oil passage 9B. The other end of the annular space 23 is connected to the cylindrical portion 1 of the lid 17.
7B.

Reference numeral 24 denotes a ring-shaped piston which is located in the annular space 23 and is slidably fitted on the outer peripheral side of the valve guide 15. The valve casing 13 is formed so as to be slidably fitted with a small gap, and the outer peripheral surface thereof is in sliding contact with the peripheral surface of the housing hole 13A of the valve casing 13. Further, the piston 2
An annular recess 24A is formed on the inner peripheral side of the outer ring 4 and an O-ring 25 as a seal member is formed in the annular recess 24A.
Are disposed so as to slide on the outer peripheral surface of the valve guide 15 in an elastically deformed state.

Here, the piston 24 defines an oil storage chamber 26 in the annular space 23 between the piston 24 and the cylindrical portion 17B of the lid 17,
The oil storage chamber 26 is always in communication with the spring chamber 19 via a communication hole 27 described later. When the relief valve element 18 performs low pressure relief at the pressure P2 shown in FIG.
The piston 24 is positioned in the annular space 2 so that the volume of
3 is displaced toward the stopper 13B located on one side.

Reference numeral 27 denotes a radial communication hole formed in the other cylindrical portion 15B of the valve guide 15, and the communication hole 27
7 is open to the oil storage chamber 26 at the tip end side of the cylindrical portion 17B, and the spring chamber 19 in the valve guide 15 is always communicated with the oil storage chamber 26 with a certain restriction. And the relief valve element 18
At the time of low-pressure relief of the spring chamber 19 through the orifice 20 of the relief valve body 18 from the actuator side oil passage 9A.
The pressure oil flowing into the oil storage chamber 26 is supplied to the oil storage chamber 26 through the small-diameter communication hole 27, and the piston 24 stops in the annular space 23 by the pressure of the pressure oil generated in the oil storage chamber 26. Sliding displacement occurs to a position where it comes into contact with 13B.

Although one relief valve 12A of the pair of relief valves 12A and 12B has been specifically described, the other relief valve 12B has the same configuration, and a detailed description thereof will be omitted. And

Prior art relief valves 12A and 12B
Has the above-described configuration, and its operation will be described below.

First, the operation of the hydraulic motor drive circuit will be described. When the operator switches the direction switching valve 5 from the neutral position (a) to the switching position (c),
Pressure oil from the hydraulic pump 3 is supplied to the hydraulic motor 1 via the pipeline 2B. At this time, the pressure oil from the hydraulic pump 3 is supplied from the hydraulic source side oil passage 8B to the pilot line 11B of the counter balance valve 10, and the counter balance valve 10
Is also switched to the switching position (c). As a result, the oil pressure path 8A, the actuator oil path 9A, and the oil pressure path 8B
And the actuator side oil passage 9B communicate with each other,
Pressure oil is supplied to the motor 1 . As a result, the hydraulic motor 1 rotates in the direction of arrow F, and the inertial body connected to the rotating shaft of the hydraulic motor 1 rotates.

On the other hand, when the operator switches the direction switching valve 5 from the switching position (c) to the neutral position (a), the supply of the pressure oil from the hydraulic source side oil passage 8B to the actuator side oil passage 9B is stopped. Therefore, the pressure in pilot line 11B decreases, and counter balance valve 10 returns to neutral position (a). Thus, the connection between the hydraulic pressure source side oil passage 8A and the actuator side oil passage 9A is interrupted.

However, since the hydraulic motor 1 continues the inertial rotation by the inertial force of the inertial body connected to the rotary shaft, even after the directional control valve 5 is switched to the neutral position (a), the hydraulic motor 1 is still connected to the actuator side oil passage 9B. The pressure oil is sucked and discharged into the actuator-side oil passage 9A to perform a pump action. Since the return of the pressure oil to the tank 4 is prevented by the counterbalance valve 10, the pressure of the actuator-side oil passage 9A gradually increases.

Thus, the hydraulic pressure on the actuator side oil passage 9A becomes high, and the hydraulic brake is applied as the brake pressure of the hydraulic motor 1. When the pressure in the actuator-side oil passage 9A reaches the relief pressure (P1 or P2 in FIG. 4) of the relief valve 12A, the relief valve 12A opens and relieves the pressure oil to the actuator-side oil passage 9B. At this time, the inertial energy of the hydraulic motor 1 is absorbed by the resistance of the pressure oil flowing through the relief valve 12A, and the hydraulic motor 1 is gradually stopped.

Next, the operation of the relief valve 12A at the time of relief will be described with reference to a characteristic diagram shown in FIG.

First, the accumulator 2 of the relief valve 12
As shown in FIG. 3, the piston 24 that constitutes the piston 2 is normally located on the other side of the annular space 23 (hereinafter, referred to as an “initial position”) due to the pressure in the actuator-side oil passage 9 </ b> B. 26 has a minimum volume.

When the pressure in the actuator-side oil passage 9A gradually increases from time t0 to time t1 in FIG. 4, the pressure oil in the actuator-side oil passage 9A flows through the orifice 20 of the relief valve body 18 to the valve guide 15. Flows into the spring chamber 19, and is supplied from the inside of the spring chamber 19 into the oil storage chamber 26 through the communication hole 27. Thereby, the piston 24 is displaced toward the stopper 13B from the time point t1 to the time point t2 in FIG.

From the initial position until the piston 24 reaches the stroke end (time t1 to time t2),
The volume of the oil storage chamber 26 is gradually expanded, and the pressure oil in the spring chamber 19 is continuously supplied to the oil storage chamber 26. As a result, the pressure in the spring chamber 19, that is, the pressure on the other end side of the relief valve element 18, temporarily decreases, and the relief valve element 18
The valve is opened only during the period from the time point t1 to the time point t2 even though the pressure P2 is lower than the predetermined relief set pressure P1. As a result, the actuator side oil passages 9A and 9B communicate with each other, and the pressure oil in the actuator side oil passage 9A
The fluid flows through the actuator-side oil passage 9B through the pressure passage 6 (low-pressure relief operation).

Next, after the piston 24 comes into contact with the stopper 13B and the stroke ends (after time t2),
Since the supply of the pressure oil from the spring chamber 19 to the oil storage chamber 26 is stopped, the pressure in the spring chamber 19 is reduced to the actuator-side oil passage 9A.
And the relief valve element 18 closes.

Further, when the pressure in the actuator-side oil passage 9A continues to increase and reaches a predetermined relief set pressure P1 of the relief valve 12A at a time point t3 in FIG. 4, the relief valve body 18 opens again. Actuator side oil passage 9A
The pressure oil in the actuator is passed through the oil chamber 16 to the actuator side oil passage 9B.
(High pressure relief operation).

As described above, the relief valve 12A (12B)
Prevents sudden stop of the inertial body by absorbing the inertial force of the inertial body in two stages, that is, at the time of low pressure relief and at the time of high pressure relief.

[0040]

Incidentally, in the above-described relief valve 12A (12B) according to the prior art, one side cylindrical portion 15A of the valve guide 15 is formed to have a smaller diameter than the other side cylindrical portion 15B. This is because the relief valve 12A (12
B) is to be assembled according to the following procedure.

That is, first, the relief valve element 18 and the setting spring 2
1 and the like are assembled in the valve guide 15, and the lid 17 is inserted into the other cylindrical portion 15B of the valve guide 15. Next, the valve guide 1
5, the piston 24 is inserted into the outer peripheral side of the valve guide 15 from the one side cylindrical portion 15A toward the other side cylindrical portion 15B, and then the one side cylindrical portion 15A of the valve guide 15 is inserted into the valve seat 14. . The valve seat 14, the valve guide 15, the lid 17, the piston 2
4 and the like are screwed into the valve casing 13.

In the manufacturing method described above, the piston 24
Of the valve guide 15 from the one side cylindrical portion 15A to the other side cylindrical portion 15B, the one side cylindrical portion 15A of the valve guide 15 is formed to have a smaller diameter than the other side cylindrical portion 15B. 24 is easily inserted.

However, if one side cylindrical portion 15A of the valve guide 15 is formed to have a smaller diameter than the other side cylindrical portion 15B, the one side cylindrical portion 15A
A, the volume of the oil chamber 16 in A becomes small, and at the time of the relief operation, the relief valve element 18 opens, and the actuator side oil passage 9A (9B) moves from the actuator side oil passage 9B (9).
When the pressure oil flows toward (A), there arises a problem that a vortex or the like is generated in the oil chamber 16.

Due to the influence of the vortex and the like, the relief valve 1
8 is susceptible to a large back pressure, and has a problem that the override characteristic of the relief valve element 18 deteriorates and the actual valve opening pressure becomes excessively higher than the relief set pressure P1.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to prevent the valve opening operation from becoming unstable due to the influence of the back pressure or the like on the relief valve body and improve the override characteristics. It is an object of the present invention to provide a relief valve with an accumulator that can perform the above operation.

[0046]

According to a first aspect of the present invention, a pair of a hydraulic source side oil passage and an actuator side oil passage are formed between a hydraulic source and an actuator. And a valve casing formed with a receiving hole that opens to the outside, and a cylindrical valve seat provided between the pair of actuator-side oil passages located at a depth side of the receiving hole of the valve casing. When inserted from the opening end side into the accommodation hole of the valve casing, one end side extending to the depth side of the accommodation hole is fitted to the outer peripheral side of the valve seat, and extends from one end side to the other end side. a cylindrical valve guide formed in equal correct cylindrical outer diameter, the valve guide is fitted to the other end periphery to close the other end of the valve guide, the open end side of the receiving hole A lid closing the opening end of the accommodation hole by being screwed into A relief valve body slidably provided in the valve guide so as to be separated from and seated on the valve seat, the other end of the relief valve body defining a spring chamber in the valve guide between the cover body and the relief valve body; An orifice communicating the spring chamber with one of the actuator-side oil passages of the pair of actuator-side oil passages, and an orifice for biasing a relief valve body toward the valve seat. A setting spring that is disposed in a spring chamber and normally closes the relief valve body, and that allows the relief valve body to open when the pressure in the actuator-side oil passage reaches a relief set pressure; An accumulator for temporarily lowering the relief valve body to a low pressure at a pressure lower than the relief set pressure, the accumulator comprising:
One end side is formed in the outer peripheral side of the valve guide and located in the accommodation hole of the valve casing, one end side communicates with the other one of the actuator side oil passages, and the other end side is closed by the lid. An annular space, a ring-shaped piston slidably fitted on the outer peripheral side of the valve guide, and defining an oil storage chamber in the annular space; and a spring drilled in a radial direction of the valve guide. And a communication hole for constantly communicating the chamber with the oil storage chamber.

[0047] As the above-described configuration, the valve guide from one end by the outside diameter over the other end side is formed at an equal correct cylindrical shape, position and the valve guide between the valve seat and the relief valve body The volume of the oil chamber (space) formed on one end side can be increased. In the relief operation, when the relief valve is opened, the flow of the pressure oil flowing from one actuator side oil passage to the other actuator side oil passage can be made smooth.

[0048] In a state where the piston of the accumulator is in the initial position to minimize the volume of the oil storage chamber, when one of the actuator side oil passage becomes high, the pressure oil from the actuator side oil passage of the relief valve body together flows into the spring chamber through the orifice, the pressure oil is Ru is supplied from the spring chamber through the communication hole to the oil storage chamber of the annular space. This
Ri, the piston of the accumulator is displaced to one side of the ring-shaped space so as to enlarge the volume of the oil storage chamber, the pressure of the spring chamber is reduced, the relief valve body a low pressure relief by temporarily opening Do.

According to the second aspect of the present invention, the relief valve is slidably provided on the inner periphery of one end of the valve guide, and the lid is fitted on the other end. The lid and the valve guide are assembled as an integral unit in the housing hole of the valve casing in a state where the piston is inserted and mounted on the outer peripheral side of the valve guide. A stopper is provided near the one end side of the annular space to regulate the stroke end of the piston between the lid and the lid.

With this configuration, the relief
The valve guide with the valve is assembled together with the lid and piston, etc.
It is assembled as one piece, and this one piece is assembled in the accommodation hole of the valve casing.
Can be included. After the assembly, at the time of the low-pressure relief operation, when the pressure oil in the spring chamber is supplied to the oil storage chamber side of the annular space via the communication hole, the piston is displaced to one side of the annular space, but the valve casing is closed. When the piston comes into contact with the stopper, the stroke end of the piston is regulated.

[0051] Further, in the invention according to claim 3, wherein the communication hole, between one end surface and the piston of the lid
Consisting of a hole formed in the valve guide with a throttle at
The communication hole is formed with a tapered surface that gradually expands on the outer peripheral side of the valve guide, and a seal member that seals between the outer peripheral surface of the valve guide and the inner peripheral side of the piston is provided. .

Thus, during the production of the relief valve, for example, from the other end to the one end of the valve guide,
It is fitted to the outer peripheral side of the valve guide piston, with the stop
Since the burr or the like is suppressed in the communication hole by the tapered surface portion, it is possible to prevent the seal member provided on the inner peripheral side of the piston from being damaged or scratched on the tapered surface side of the communication hole.

[0053]

FIG. 1 is a block diagram showing an embodiment of the present invention.
Will be described in detail. In this embodiment, the same components as those of the above-described prior art are denoted by the same reference numerals, and description thereof will be omitted.

In the drawing, reference numeral 31 denotes a relief valve with an accumulator according to the present embodiment (hereinafter referred to as "relief valve 31"). The relief valve 31 is the same as the prior art relief valve 12A (12B). It is provided in the middle of the oil passages 9A and 9B. The relief valve 31 is a conventional relief valve 12A, 1A.
Similarly to 2B, two are provided in the hydraulic motor drive circuit and are integrally provided in a valve casing 32 to be described later. In this embodiment, only one relief valve 31 will be described, and the other will be described. Is omitted.

Reference numeral 32 denotes a valve casing according to the present embodiment. The valve casing 32 has a hydraulic source side oil passage 8A, 8B and an actuator side oil passage 9A, 9B inside, similarly to the valve casing 13 according to the prior art. A receiving hole 32A for receiving a valve guide 34 to be described later is formed. Further, a stopper 32B for regulating the stroke end of the piston 40 described later is formed in the accommodation hole 32A.

Reference numeral 33 denotes an accommodation hole 32A of the valve casing 32.
FIG. 6 shows a cylindrical valve seat according to the present embodiment, which is provided at a depth side and provided between actuator-side oil passages 9A and 9B;
Numeral 3 is formed in a stepped cylindrical shape in substantially the same manner as the valve seat 14 according to the prior art, and has an insertion portion 33A, a fitting portion 33B, and a valve seat portion 33C.
have. However, in the valve seat 33 according to the present embodiment, the outer diameter of the fitting portion 33B is different from the fitting portion 1 of the valve seat 14 according to the prior art.
It has a larger diameter than 4B.

[0057] 34 indicates a valve guide of the present embodiment provided in the valve housing 32, valve guide 34, substantially similarly to the valve guide 15 according to the prior art, the valve casing 3
It is inserted into the second accommodation hole 32A from the opening end side. Soshi
The valve guide 34 extends to the depth side of the accommodation hole 32A. One end side is a one-side cylindrical portion 34A fitted to the outer peripheral side of the fitting portion 33B of the valve seat 33, and the other end side is described later. The other-side cylindrical portion 34B becomes a closed end when the lid 36 is inserted. Further, a valve body sliding hole 34C into which the relief valve body 18 is slidably inserted is formed closer to one side of the axial center of the valve guide 34.

However, the valve guide 34 according to this embodiment is
It is formed in a cylindrical shape having substantially the same outer diameter from one end to the other end. That is, the valve guide 34 is a straight cylinder whose outer diameter does not change.
The one-side cylindrical portion 34A and the other-side cylindrical portion 34B are set to have substantially the same outer diameter within the range of manufacturing tolerance. As a result, the valve guide 34 according to the present embodiment greatly increases the size of the one-side cylindrical portion 34A as compared with the valve guide 15 of the relief valves 12A and 12B according to the related art.

In the cylindrical portion 34A of the valve guide 34, flow holes 34D, 34D,... Are formed in the radial direction, and are located between the relief valve body 18 and the valve seat 33 so that the valve guide 3
An oil chamber 35 is defined in the one side cylinder portion 34A.

Reference numeral 36 denotes the outer periphery of the other cylindrical portion 34B of the valve guide 34.
Into the receiving hole 32A of the valve casing 32
A lid screwed from the opening end side is shown. The lid 36 is formed in a bottomed cylindrical shape from a bottom portion 36A and a cylindrical portion 36B, and the bottom portion 36A of the lid 36 is formed of the other side cylindrical portion 34B. The end is closed. The cylindrical portion 36B of the lid 36 is formed to be thick, so that the valve guide 34 is radially separated from the valve casing 32 by the thickness of the cylindrical portion 36B. An annular space 38 described below is formed between the valve casing 32 and the housing hole 32A .

[0061] 37 denotes an accumulator according to this embodiment, the accumulator 37 is substantially similar to the accumulator 22 according to the prior art, the accommodation hole 3 of the valve housing 32
2A, an annular space 38 formed on the outer peripheral side of the valve guide 34 , and a valve guide 3 located in the annular space 38.
A ring-shaped piston 40 slidably fitted on the outer peripheral side of the cylinder 4 and defining an oil storage chamber 39 in the annular space 38 ;
36 is bored in the radial direction of the other cylindrical portion 34B of the valve guide 34 at a position close to the one end side end surface, and the spring chamber 1 in the valve guide 34 is provided.
It is constituted by 9 and the said annular space 38 and passage 41 for constantly communicated with a certain aperture. Then, the said piston 40 the inner periphery side is formed an annular recess 40A of, O-ring 42 as a sealing member is disposed.

However, the accumulator 3 according to the present embodiment
7 is different from the prior art in that an opening 41A is formed as a tapered surface that gradually expands on the outer peripheral side of the valve guide 34. And valve guide 3
The opening 41 </ b> A of the communication hole 41 located on the outer peripheral side of the valve guide 4 expands in a tapered shape on the outer peripheral side of the valve guide 34,
Drilling work (machining) of the communication hole 41 on the outer peripheral surface of the valve guide 34
Burrs and the like are suppressed, and the outer peripheral surface of the valve guide 34 is formed as a smooth cylindrical surface.

The relief valve 31 according to the present embodiment has the above-described configuration, and its basic operation is substantially the same as the conventional relief valves 12A and 12B.

Next, the manufacture of the relief valve 31 will be described. First, on the outer peripheral side of the valve guide 34, the other-side cylindrical portion 3
The piston 40 is inserted together with the O-ring 42 from 4B toward the one-side cylindrical portion 34A, and the piston 40 is inserted through the outer peripheral side of the valve guide 34 to a position beyond the opening 41A of the communication hole 41. Next, the relief valve element 18,
The setting spring 21 is incorporated, and the other cylindrical portion 34B of the valve guide 34 is incorporated.
The cover 36 is fitted on the outer peripheral side and the valve guide 34
Inserting the engaging portion 33B of the valve seat 33 at one side cylindrical portion 34A of the
As a result, the valve seat 33, the valve guide 34, the piston 4
0, the lid 36 and the like are assembled as an integral body. Its to, this
Et of the valve seat 33, valve guide 34, the piston 40, the lid 36
The integral body consisting of such, housing hole 32A of the valve housing 32
Into the inside from the opening end side, and collect the cylindrical portion 36B side of the lid 36.
By screwing the open end side of Yoana 32A, the Lili
Assemble the valve 31.

Thus, the relief valve 31 according to the present embodiment
, The valve located between the and Turkey be formed substantially equal cylindrical outer diameter over the other end of the valve guide 34 from one end, the valve seat 33 and the relief valve body 18 guide 34
The volume of the oil chamber 35 formed in the one side cylindrical portion 34A can be enlarged.

In this way, during the relief operation, when the relief valve element 18 is opened, it is possible to effectively prevent eddies or the like from being generated in the oil chamber 16, so that one of the actuator side oil passages 9 A is connected to the other. The flow of the pressure oil flowing toward the actuator-side oil passage 9B can be made smooth.

Therefore, the back pressure of the relief valve 31 during the relief operation can be reduced, the relief set pressure P1 is always stabilized at a predetermined pressure, and the relief characteristics and accuracy of the relief valve 31 are greatly improved. it can.

Further, since the valve guide 34 is formed in a cylindrical shape having substantially the same outer diameter from one end to the other end, machining of the valve guide 34 can be facilitated.

Further, the piston 4 of the accumulator 37
The valve guide 34 is formed in a cylindrical shape having substantially the same outer diameter from one end to the other end by forming the stopper 32B for regulating the stroke end integrally with the valve casing 32. It is possible to do.

That is, even if the stopper 32B is formed integrally with the outer peripheral side of the valve guide 34, it is possible to fulfill the function of restricting the stroke end of the piston 40. However, as in the relief valve 31 according to the present embodiment, by forming the stopper 32B integrally with the valve casing 32, the valve guide 34 is formed in a cylindrical shape having substantially the same outer diameter from one end to the other end. And oil room 3
5 can be larger, it is possible to obtain an effect of preventing the occurrence of vortex during the relief as described above.

On the other hand, the communication hole 41 of the accumulator 37
The opening 41A that gradually expands on the outer peripheral side of the valve guide 34
Is formed, it is possible to reliably prevent burrs or the like from being formed in the opening 41A of the communication hole 41 in a drilling operation or the like. Accordingly, when the relief valve 31 is manufactured, when the piston 40 is inserted into the outer peripheral side of the valve guide 34 from the other cylindrical portion 34B of the valve guide 34 toward the one cylindrical portion 34A, the O of the piston 40 is The ring 42 can be prevented from being damaged on the opening 41A side of the communication hole 41 and from being scratched.

Therefore, damage to the O-ring 42 during the manufacturing process can be prevented, the yield of the relief valve 31 can be increased, and durability and reliability can be improved.

In the above embodiment, the radial piston type hydraulic motor 1 is taken as an example of the actuator. However, the present invention is not limited to this. For example, a swash plate type hydraulic motor,
Other actuators such as an oblique-axis hydraulic motor may be used.

Further, in the above-described embodiment, the hydraulic motor drive circuit of a hydraulic shovel, a hydraulic crane, or the like has been described as an example. However, the present invention is not limited to this, and may be applied to various hydraulic motor drive circuits provided in a construction machine. Can be applied.

[0075]

Ri above in detail the passage according to the present invention, according to the invention described in claim 1, a valve guide, over the other end formed at equal correct cylindrical outer diameter from one end, the accumulator ,
An annular space formed between the valve guide and the valve casing, one end of which is in communication with the actuator-side oil passage and the other end of which is closed by a lid, is slidably inserted into the outer periphery of the valve guide. A ring-shaped piston defining an oil storage chamber in the annular space, and a communication hole formed in a radial direction of the valve guide and constantly communicating the spring chamber with the oil storage chamber, the valve seat and the relief valve are provided. The volume of the oil chamber (space) formed between the body and one end of the valve guide can be increased.

In this way, during the relief operation, it is possible to effectively prevent eddies and the like from being generated in the oil chamber, and to reduce the flow of the pressure oil flowing from one actuator side oil passage to the other actuator side oil passage. It can be smooth.

Therefore, the back pressure of the relief valve can be reduced, the relief set pressure is always stabilized at a predetermined pressure, and the relief characteristics and accuracy of the relief valve with an accumulator can be greatly improved.

[0078] By the outer diameter was formed at an equal correct cylindrical shape over the other end of the valve guide from one side, it is possible to facilitate the valve guide machining. Then, the piston of the accumulator is inserted into the outer peripheral side of the valve guide, and the other end of the valve guide is closed with a lid,
The oil storage chamber of the accumulator can be easily formed on the outer peripheral side of the valve guide between the end face of the lid and the piston.

Further, according to the second aspect of the present invention, the valve guide to which the relief valve is mounted is integrated with the lid, the piston and the like, and the integrated is mounted in the receiving hole of the valve casing. Since the valve casing is provided with a stopper which is located near one end of the annular space and regulates a stroke end of the piston between the valve casing and the lid, the lid and the valve guide are provided outside the valve casing. Can be preassembled, and the preassembled one can be inserted into the accommodation hole of the valve casing and the lid screwed onto the opening end side of the accommodation hole to assemble the relief valve. be able to. By forming the stopper integrally with the valve casing, it is not necessary to form the stopper on the valve guide side. Therefore, the outer diameter can be formed at equal correct cylindrical shape over the other end of the valve guide from one end, as described above, it is possible to realize the prevention of the vortex flow at the time of the relief operation.

Further, according to the third aspect of the present invention,
A communication hole having a throttle communicating with the oil storage chamber of the accumulator is formed in the radial direction of the valve guide between the one end surface of the lid and the piston, and the communication hole is formed on the outer peripheral side of the valve guide. A taper surface portion that gradually expands is formed, and a seal member is provided on the inner peripheral side of the piston to seal between the outer peripheral surface of the valve guide. And at the time of manufacturing the relief valve with the accumulator, it is possible to prevent burrs and the like from being generated in the opening of the communication hole.

Accordingly, the pressure oil in the spring chamber is supplied through the communication hole.
Together we can be supplied to the oil storage chamber, and set the inner peripheral side of the piston
The girder seal member was damaged on the tapered surface side of the communication hole .
Ri, it is possible to reliably prevent that of vinegar or can scratches, etc., it is possible to improve the yield of products.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a relief valve with an accumulator according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a hydraulic motor drive circuit using a brake valve according to the related art.

FIG. 3 is a sectional view showing a relief valve with an accumulator according to the related art.

FIG. 4 is a characteristic diagram showing a change in a valve opening pressure of a relief valve body with respect to a lapse of time of a relief valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic motor (actuator) 3 Hydraulic pump (hydraulic source) 8A, 8B Hydraulic source side oil passage 9A, 9B Actuator side oil passage 18 Relief valve body 19 Spring chamber 20 Orifice 21 Setting spring 31 Relief valve with accumulator 32 Valve casing 32B Stopper 33 valve seat 34 valve guide 35 oil chamber 36 lid 37 accumulator 38 annular space 39 oil storage chamber 40 piston 41 communication hole 41A opening (tapered surface) 42 O-ring (seal member)

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F15B 11/00-11/22 F16K 3/00-3/36 F16K 17/00-17/168

Claims (3)

(57) [Claims] 1. A valve casing having a pair of hydraulic-source-side oil passages and an actuator-side oil passage formed between a hydraulic pressure source and an actuator, and having a receiving hole that opens to the outside, A cylindrical valve seat provided between the pair of actuator-side oil passages located on the back side of the housing hole, and inserted into the housing hole of the valve casing from an opening end side, one end extending to the back office side of the receiving hole is fitted on the outer peripheral side of the valve seat, the outer diameter dimension equal correct cylindrical shape formed in a cylindrical valve guide over from one end to the other end A lid fitted to the outer periphery of the other end of the valve guide to close the other end of the valve guide, and screwed to the open end of the accommodation hole to close the opening end of the accommodation hole; And one end side is slidably provided in the valve guide so as to be separated from and seated on the valve seat. A relief valve body having an end side defining a spring chamber in the valve guide between the lid body and the relief valve body; and the spring chamber is formed of the pair of actuator-side oil passages. An orifice communicating with one of the actuator-side oil passages; and an orifice disposed in the spring chamber for urging the relief valve body toward the valve seat, and normally closing the relief valve body,
A setting spring that allows the relief valve to open when the pressure in the actuator-side oil passage reaches a relief set pressure; and temporarily reducing the pressure of the relief valve at a pressure lower than the relief set pressure. An accumulator to be relieved, the accumulator being formed in an accommodation hole of the valve casing and formed on an outer peripheral side of the valve guide, and having one end communicating with the other actuator-side oil passage among the actuator-side oil passages. An annular space whose other end is closed by the lid; a ring-shaped piston slidably fitted on the outer peripheral side of the valve guide to define an oil storage chamber in the annular space; A relief valve with an accumulator, which is formed in a radial direction of the guide and includes a communication hole that constantly communicates the spring chamber with the oil storage chamber. 2. The valve guide, wherein the relief valve body is slidably provided on one inner side of the valve guide, the lid body is fitted on the other end side, and the relief body is provided on the outer peripheral side of the valve guide. The lid and the valve guide are assembled as an integral unit in the accommodation hole of the valve casing with the piston inserted and attached, and the lid is positioned on the valve casing near one end of the annular space. 2. A relief valve with an accumulator according to claim 1, further comprising a stopper for restricting a stroke end of said piston. Wherein said communication hole, and the one end face of the lid
Consists holes formed before Kiben guide with an aperture between the piston, the the communicating hole form a tapered surface portion gradually widened on the outer peripheral side of the valve guide, the inner peripheral side of the piston 3. The relief valve with an accumulator according to claim 1, wherein a seal member is provided for sealing between the valve guide and an outer peripheral surface of the valve guide.