JPH0835565A - Valve plug - Google Patents

Abstract

PURPOSE:To maintain the cut-off state between the high and low pressure passages without destroying a valve seat, by installing a valve body set on a valve seat between the high and low pressure passages, a cover member which is screwed with the valve body through the fitting of the valve body in a slidable manner, elastic body arranged in a back pressure chamber between the valve body and the cover member, and a passage for the communication between the back pressure chamber and the high pressure passage on the valve body. CONSTITUTION:The valve body part 52B of a valve body 52 is brought into contact with a valve seat 60 at the end of a through hole 22, and the communication between a high pressure passage 14 and a low pressure passage 17 through a through hole 22 is cut off. A cover member 51 is screwed, and the valve body part 52B is pressed against the valve seat 60. In this case, the cover member 51 slides on the outer periphery of the shaft part 52A of the valve body 52, deforming a spring washer 53, and the pressing force due to the screwing of the cover member 51 is applied to the valve body 52, together with the springy force of the spring washer 53 in a back pressure chamber, and the valve member 52B is pressed on the valve seat 60 by a prescribed pressing force. When the cover member 51 is abuttingly engaged with the body 2, the shift of the cover member 51 is suppressed. Accordingly, the spring washer 53 sets the valve body part 52B by the pressing force free from the destruction of the valve seat 60, and a cut-off state can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve plug which shuts off a high pressure passage and a low pressure passage of a valve.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No.
There is a directional control valve described in Japanese Patent No. 7864. In this type of directional control valve, an overload relief valve can be attached to the main body if necessary, so that a port that connects the supply / discharge passage and the discharge passage is formed.

When the overload relief valve 48 is not necessary, the port 100 is provided as shown in FIG.
After the valve body 103 is attached, the valve body 103 is screwed into the valve seat 102 and seated on the valve seat 102 of the supply / discharge passage 38.
The lid member 1 screwed to the outer periphery in order to prevent the rotation of 3
With the valve plug 105 composed of 04 and 04,
8 is cut off from the discharge passage 37 to prevent the hydraulic pressure from being introduced from the supply / discharge passage 38 to the discharge passage 37 side.

[0004]

However, in the conventional valve plug, the lid member 104 is screwed to the valve body 103, and the lid member is rotated to press the valve body 103 against the valve seat 102. Then, this rotation causes a tension that pulls the valve element 103 away from the valve seat 102. Therefore, in order to maintain the above-mentioned cutoff state between the supply passage 38 and the discharge passage 37, this tension is exceeded. It is necessary to press the valve element 103 against the valve seat 102 with the pressing force of
There was a problem of destroying 2.

The present invention has been made to solve this problem, and maintains the high-pressure passage and the low-pressure passage in a disconnected state without destroying the valve seat formed between the high-pressure passage and the low-pressure passage. The object is to provide a valve plug capable of

[0006]

In order to solve the above problems, in the valve plug of the present invention, in claim 1, a valve seat is formed between the high pressure passage and the low pressure passage of the valve, and the valve seat is formed in this valve seat. In a valve plug that is seated and constantly shuts off the high-pressure passage and the low-pressure passage, a valve body that is seated on the valve seat and a lid member that is slidably fitted to the valve body and screwed onto the valve And an elastic body arranged in a back pressure chamber defined between the valve body and the lid member, and a passage communicating the back pressure chamber and the high pressure passage with the valve body, The elastic body prevents the valve seat from being broken and always has a pressing force for seating the valve body.

In the second aspect, in addition to the first aspect,
The valve body and the back pressure chamber have a cross-sectional area larger than the opening cross-sectional area of the high-pressure passage.

According to a third aspect of the present invention,
The elastic body includes a disc spring, a spring washer, or a torsion bar.

According to a fourth aspect of the present invention, a valve seat is formed between the high pressure passage and the low pressure passage of the valve, and the valve plug is seated on the valve seat to constantly shut off the high pressure passage and the low pressure passage. It comprises a valve body seated on a valve seat and a lid member which is slidably fitted to the valve body and screwed onto the valve.

[0010]

According to the above-described valve plug of the present invention, in the first and fourth aspects, the valve member, which is pressed against the valve seat to bring the high pressure passage and the low pressure passage into the closed state, is provided in the lid member. Since it is slidably arranged, when the valve plug is attached to the valve, the pressing force due to the screwing of the lid member is transmitted to the valve body through the elastic body and pressed against the valve seat, so that the valve seat Can prevent damage.

In the second aspect, when the valve is operated, the oil pressure is introduced into the back pressure chamber through the passage of the valve body, but the cross-sectional area of the valve body and the back pressure chamber passage is high. Since the cross-sectional area is larger than the opening cross-sectional area of the passage, there is an area difference between the pressure receiving area of the valve body on the high pressure passage side and the pressure receiving area of the valve body on the back pressure chamber side. As a result of the combined force of the force introduced into the back pressure chamber acting on the valve element and the screwing of the lid member when the valve plug is attached, the force acting on the valve element from the high pressure passage side is overcome, and the valve element is closed. It is not moved to the member side.

According to the present invention, when the valve is actuated, the hydraulic pressure on the high pressure passage side acts so as to push the valve body in the direction of separating it from the valve seat, but the lid member Since the valve body does not move because it is engaged with
It is possible to maintain the shut-off state between the valve body and the valve seat.

[0013]

【Example】

Example 1 Hereinafter, a valve plug which is Example 1 of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a directional control valve to which the valve plug of the first embodiment is applied, and FIG. 2A is an enlarged view of a main part of the valve plug of the first embodiment in FIG. 2 (b) is a plan view showing the structure of the lid member of the valve plug in the first embodiment, FIG. 2 (c) is a side view showing the structure of the spring washer of the valve plug, and FIG. 3 is the valve plug of the first embodiment. FIG. 4 is a transverse cross-sectional view of a main part showing a procedure for attaching the directional control valve to the directional control valve, and FIG. 4 is a transverse sectional view showing a configuration for operating the directional control valve to which the valve plug of the first embodiment is attached.

In FIG. 1, reference numeral 1 denotes a directional switching valve, which is arranged in series with another directional switching valve (not shown) to form a multiple directional switching valve device and is arranged at a predetermined position of a construction machine. is there.

This directional control valve 1 comprises a block-shaped main body 2
A spool 3 is provided in the main body 2, and a spool charging hole 4 is provided in the main body 2 and enlarged portions 5-1 are provided in the charging hole 4.
3, a high-pressure passage 14 following the expansion portion 6, a bridge passage 15 following the expansion portions 7 and 11, a high-pressure passage 16 following the expansion portion 12,
It has low-pressure passages 17 and 18 following the enlarged portions 5 and 13, respectively. The enlarged portions 5 and 13 are the same as the tank passage 1
The tank T is connected through 9 to a tank (not shown).

Further, the low pressure passages 17 and 18 are formed in the side surfaces 2B and 2C of the main body 2 respectively so as to open and communicate with the valve ports 20 and 21.

An unillustrated overload relief valve is usually arranged in the valve ports 20 and 21 as needed, but in the present embodiment, there is a case where the above overload relief valve is not necessary. A valve plug 50, which is shown and will be described in detail later, is screwed. Further, the insides of the valve ports 20 and 21 are provided with through holes 22 and 23.
The high pressure passages 14 and 16 can be communicated with each other via the valve plug 50. However, by screwing the valve plug 50, the low pressure passage 17 and the high pressure passage 14 and the low pressure passage 18 and the high pressure passage 1 are connected by the valve plug 50.
6 and 6 are closed respectively.

The high pressure passages 14 and 16 are formed in the upper surface 2A of the main body 2 and are formed in the cylinder ports 24 and 2, respectively.
5, the cylinder ports 24 and 25 are screwed with bolts 26 and 27 to close the cylinder ports 24 and 25. Further, the bridge passage 15 can communicate with an oil supply passage 28 communicating with a hydraulic pump (not shown) via a check valve G. Further, the cylinder ports 24 and 25 are usually connected to each chamber of an actuator such as a cylinder (not shown) through piping.

The spool 3 has annular grooves 30, 31, 32,
When the spool 3 moves leftward or rightward, the annular groove 30 changes the enlarged portion 6 to the enlarged portion 5 or 7, and the annular groove 33 changes the enlarged portion 12 to the enlarged portion 13 or 11. It is designed to communicate. Reference numeral 34 denotes a spring that holds the spool 3 at a neutral position (the position shown in FIG. 1) and is stretched in a cover body 36 that defines the spool chamber 35. The spool 3 is moved against the spring 34.

Next, the structure of the valve plug 50 in the first embodiment will be described in detail with reference to FIGS. 2 (a) to 2 (c).

In FIG. 2A, the valve plug 50 is composed of a lid member 51, a valve body 52 and a spring washer 53 which is an elastic body.

As shown in FIG. 2B, the lid member 51 is composed of a hexagonal head member 51A and a shaft member 51B extending from the head member 51A. The shaft member 51B has a head opening at its end face. A recess 54 extending toward the member 51A is formed. The recess 54 has an opening area Aa of the through hole 22.
Cross-sectional area Ab (diameter d2) (d1) larger than (diameter d1)
<Relationship of d2). A seal groove 55A in which the screw portion 51b and the seal ring 55 are fitted is formed on the outer peripheral surface of the shaft member 51B.

The valve body 52 includes a shaft portion 52A and the shaft portion 52A.
A conical valve body portion 52B that is reduced in diameter and protrudes from is integrally formed, and a communication passage 56 that penetrates in the axial direction and that penetrates is formed. The valve body 52 is slidably fitted into the lid member 51 from the end side of the shaft portion 52, and a back pressure chamber A is formed between the end of the shaft portion 52A and the bottom of the recess 54. ing. Reference numeral 57 is a seal ring that is fitted together with the backup ring 58 in a groove 57A formed by opening the outer peripheral surface of the valve body 52. Further, the shaft portion 52A of the valve body 52 has a cross-sectional area Ab that is substantially the same as the recess 54.

The spring washer 53 is provided with a notch 53A on the outer periphery thereof, and under no load in the axial direction, as shown in FIG. 2 (c), the notch 53A.
Both ends 53a and 53b are elastically movable at a predetermined position in the axial direction with A as a boundary in a mutually opposing state (valve element 52).
The valve body portion 52B is made elastic so that the valve seat 60, which will be described later, does not break. The spring washer 53 is fitted into the back pressure chamber A via an annular plate member 59 between the spring washer 53 and the end of the shaft portion 52A of the valve body 52.

As described above, the valve plug 50 of the first embodiment is
The valve member 52 and the spring washer 53 are incorporated in the lid member 51. Next, the valve plug 50 is connected to the valve port 20.
Figure 3 shows the procedure for attaching to the (direction switching valve 1).
A description will be given based on (a) to (c).

First, in order to mount the valve plug 50, in which the valve body 52 and the spring washer 53 are incorporated in the lid member 51, to the valve port 20 of the directional control valve 1, as shown in FIG. When the shaft member 51B is screwed into the valve port 20 while being screwed with a predetermined jig (not shown), and the lid member 51 is further screwed, the pressing force due to this screwing is applied to the spring washer 53. It is transmitted, without causing large deformation of the spring washer 53,
The valve body 52 is pushed by the sling washer 53 and moves to the through hole 22 side together with the lid member 51.

Finally, as shown in FIG. 3B, the valve body portion 52B of the valve body 52 abuts on the valve seat 60 formed at the end of the through hole 22, and the high pressure passage through the through hole 22 is formed. 14 and the low pressure passage 17 are cut off.

Next, after the high pressure passage 14 and the low pressure passage 17 are shut off, the lid member 51 is further screwed to apply a pressing force to the valve body 52 which does not release the shutoff state.
The valve body portion 52B of the valve body 52 is pressed against the valve seat 60 of the through hole 22. At this time, the lid member 51, as shown in FIG. 3C, deforms the spring washer 53 while the valve body 52 is being deformed.
By sliding on the outer periphery of the shaft portion 52A of the shaft portion 52A and moving to the side of the through hole 22, the spring force generated by the deformation of the spring washer 53 and the pressing force by the screwing of the lid member 51 are applied to the valve body 52. The valve member 52B of the valve body 52 is pressed against the valve seat 60 with a predetermined pressing force. When the lid member 51 abuts and engages with the main body 2, the movement of the lid member 51 is stopped, and the spring washer 53 constantly seats with a pressing force that does not destroy the valve body portion 52B of the valve body 52. It keeps the cutoff state.

As a result, the best pressure can be applied to the valve body 52 by screwing the lid member 51, and as a result, the valve seat 60 has a pressing force enough to break the valve seat 60. Therefore, the high-pressure passage 16 and the low-pressure passage 18 are maintained in the cutoff state.

3 (a) to 3 (c) show the procedure for attaching the valve plug 50 to the valve port 20 of the directional control valve 1, the same applies to the valve port 21 of the directional control valve 1. The valve plug 50 is attached by the procedure.

In this way, the directional control valve 1 having the valve plugs 50 attached to the valve ports 20 and 21 respectively, as shown in FIG. 4, has the bolts 26 and 27 of the cylinder ports 24 and 25 removed during use. , Are connected to the respective rooms of the cylinder C via pipes 65 and 66.

A cover body 38 for partitioning the spool chamber 37 is attached to the opposite side of the cover body 36 of the main body 2. The cover bodies 36, 38 are provided with pilot ports 39 opening to the spool chambers 35, 37, respectively. , 40 are formed. Piping 4 is connected to each pilot port 39, 40.
It is connected to the hydraulic pilot valve 67 via 1, 42. The hydraulic pilot valve 67 is configured as a touch lever type remote control valve and is connected to the remote control motor M and the tank T. By operating this lever 67A, the remote control motor M and the pipes 41 and 42 are communicated with each other. In addition to supplying hydraulic pressure to the pilot ports 39 and 40, the pipes 41 and 42 are connected to the tank T to return the hydraulic pressure supplied to the pilot ports 39 and 40 to the tank T.

Further, a hydraulic pump P is connected to the oil supply passage 28 through a pipe, and the pipe-oil supply passage 28-check valve G is connected.
-By supplying hydraulic pressure to each chamber of the cylinder C through the bridge passage 15 and the high pressure passages 14 and 16,
Operate.

If necessary, the valve plug 50 is removed from the valve ports 20 and 21, and an overload relief valve (not shown) is attached to the valve ports 20 and 21. In FIG. 4, what is shown in FIG. 1 is such that an operating lever (not shown) is connected to the spool 3 and the operating lever is operated to move the spool 3 to switch the direction. Since the same reference numerals have the same configuration, the description thereof will be omitted.

In FIG. 4, in order to operate the cylinder C by supplying hydraulic pressure to one chamber of the cylinder C, the lever 67A of the hydraulic pilot valve 67 is operated to operate the pilot port 40 through the pipe. The hydraulic pressure is introduced into the spool 3, and the hydraulic pressure causes the spool 3 to move toward the cover body 38 side. Finally, the high pressure passage 14 and the tank passage 19 communicate with each other, and the high pressure passage 16 and the bridge passage 15 are connected to each other. Communicate with each other.

As a result, the hydraulic pressure from the hydraulic pump P introduced into the bridge passage 15 passes through the high pressure passage 16,
The cylinder C enters into one chamber of the cylinder C through the cylinder port 25 and the pipe 66, and the cylinder C operates. At this time, a part of the hydraulic pressure is passed through the through hole 23 that opens to the high pressure passage 16 and the valve plug 50. Flowing to the side. Then, the oil pressure flowing into the through hole 23 is introduced into the back pressure chamber A through the communication passage 56 of the valve body 52. The oil pressure introduced into the back pressure chamber A maintains the valve body 52 and the valve seat 60 in the shut-off state.

That is, the shaft portion 52A of the valve body 52 has a diameter d3 larger than the diameter d1 of the through hole 23 (relationship of d1 <d3).
Therefore, there is an area difference between the pressure receiving area Aa at the end of the valve body portion 52B and the pressure receiving area Ab at the end of the shaft portion 52A of the back pressure chamber A in the valve body 52 (Aa <Ab). The spring washer 5 due to the force introduced into the back pressure chamber A due to the area difference and acting on the end of the shaft portion 52A of the valve element 52 and the screwing of the lid member 51.
As a result of the combined force with the spring force of No. 3 overcoming the force acting from the through hole 23 to the valve body portion 52B end of the valve body 52, the valve body 52 is closed by the oil pressure introduced into the high pressure passage 16. Since the valve body 52 and the valve seat 60 are not moved to the side, the shutoff state between the valve body 52 and the valve seat 60 is maintained.

From the cylinder port 25 to the cylinder C
When the hydraulic pressure is introduced into one chamber, the hydraulic pressure in the other chamber is returned to the tank T via the pipe 65-cylinder port 26-high pressure passage 14 and tank passage 19, but in this case as well, A part of the hydraulic pressure returned from the high-pressure passage 14 passes through the through hole 22 and reaches the valve plug of the valve port 20. However, like the valve plug 50 on the valve port 21 side, the movement of the valve body 52 does not occur. Instead, the high-pressure passage 14 and the low-pressure passage 17 are maintained in the disconnected state. Then, the lever 67A of the hydraulic pilot valve 67 is operated in the opposite direction to the above to introduce the hydraulic pressure to the pilot port 39,
The spool 3 is moved to the cover body 36 side, and the high pressure passage 14
Even when the hydraulic pressure is introduced from the hydraulic pump P to the other chamber of the cylinder C by communicating the bridge passage 15, the high pressure passage 16 and the tank passage 19 respectively, the valve port 20, The valve plaque 50 attached to each of the high pressure passage 14 and the low pressure passage 1
7. The high-pressure passage 16 and the low-pressure passage 18 are effectively kept in the above-mentioned cutoff state.

As described above, according to the valve plug of the first embodiment, the valve member 52, which is pressed against the valve seat 60 to bring the high pressure passages 14 and 16 and the low pressure passages 17 and 18 into the closed state, is covered with the lid member 51. Since it is slidably arranged in the recess 54, when the valve plug 50 is attached to the valve ports 20 and 21, the valve body 5
The pressing force due to the screwing of the lid member 51 is transmitted to the valve seat 2 via the spring washer 53 so as to be pressed against the valve seat 60, and the lid member 51 itself is independent of the valve body 52. Since the outer peripheral surface can be slid,
Tension for pulling the valve body 52 toward the lid member 51 is not applied, and the valve body 52 can be pressed against the valve seat 60 with the best pressing force for maintaining the shut-off state.
The valve seat 60 is not destroyed.

When the directional control valve 1 is operated,
Oil pressure is introduced into the back pressure chamber A through the communication passage 56 of the valve body 52, but the shaft portion 52A of the valve body 52 has a cross-sectional area Ab (larger than the opening cross-sectional area Aa (diameter d1) of the through hole 23 ( Diameter d
3) (relationship of d1 <d3), the valve body 52
The pressure receiving area Aa at the end of the valve body 52B and the shaft portion 52 of the back pressure chamber A
An area difference occurs between the pressure receiving area Ab at the A end (Aa <
Therefore, due to this area difference, the force introduced into the back pressure chamber A and acting on the end of the shaft portion 52A of the valve body 52 and the spring washer 5 by the screwing of the lid member 51 at the time of mounting the valve plug 50.
As a result of the combined force with the spring force of No. 3 overcoming the force acting from the through hole 23 to the valve body portion 52B end of the valve body 52, the valve body 52 is closed by the oil pressure introduced into the high pressure passage 16. Since the valve body 52 is not moved to the side, the valve body 52 is not separated from the valve seat 60, and the shutoff state can be maintained.

In the valve plug 50 of this embodiment, the elastic body disposed in the back pressure chamber A is the spring washer 53. However, the elastic body is not limited to this, and a disc spring or a torsion is used. Even if a bar is used, if the width is smaller than the diameter and the spring constant is large, the axial length of the valve plug can be shortened to maintain a predetermined shutoff state, as in the present embodiment. It is possible to achieve various effects.

Embodiment 2 Hereinafter, a valve plug which is Embodiment 2 of the present invention will be described with reference to the drawings.

FIG. 5 is a cross-sectional view showing a structure for operating the directional control valve having the valve plug of the second embodiment attached thereto.

In FIG. 5, the valve plug 150 comprises a lid member 51 and a valve body 52 having no communication passage 56, which have the same construction as in the first embodiment. And
A valve plug 150 is installed in the valve ports 20 and 21 to shut off the high pressure passages 14 and 16 and the low pressure passages 17 and 18, respectively.

In the valve plug 150, the valve body 52 is assembled in the recess 54 of the lid member 51 so as to be slidably fitted from the shaft portion 52A side through the seal ring 57 and the backup ring 58. After that, the lid member 51 incorporating the valve body 52 is screwed with a predetermined jig (not shown), and the shaft member 5 is
1B is screwed into the valve port 20 (21), and
As it is screwed, it engages with the end of the shaft portion 52A of the valve body 52, the valve body 52 is pushed, and moves together with the lid member 51 to the through hole 22 (23) side.

Finally, the valve body portion 52 of the valve body 52
B comes into contact with the valve seat, and the high pressure passage 14 (16) and the low pressure passage 17 (18) via the through hole 22 (23) are blocked.

Then, after the high-pressure passage 14 (16) and the low-pressure passage 17 (18) are shut off, the lid member 51 is placed in order to apply a pressing force to the valve body 52 that does not release the shut-off state.
Further, the valve body 52 is pressed against the valve seat 60 by screwing it by a predetermined amount.

As a result, the best pressure can be applied to the valve body 52 by screwing the lid member 51, and as a result, the valve seat 60 has a pressing force enough to destroy the valve seat 60. Is not added to the high pressure passage 14 (16) and the low pressure passage 17 (18) is maintained.

When using the directional control valve 1,
Since the operation is performed by supplying / discharging hydraulic pressure to and from one chamber of the cylinder C in the same procedure as shown in the first embodiment, detailed description thereof will be omitted.
The operation of the valve plug 150 will be described.

As shown in FIG. 5, in order to operate the cylinder C, the oil is supplied to the other chamber of the cylinder C through the hydraulic pump P, the oil supply passage 28, the check valve G, the bridge passage 15 and the high pressure passage 16. When the pressure is supplied, a part of the hydraulic pressure pushes the valve body portion 52B of the valve body 52 in the direction of separating from the valve seat 60 through the through hole 23. Since the shaft 52A of the body 52 is engaged with the end, the valve body 52 does not move and the valve body 52 and the valve seat 60 are not moved.
The cutoff state is maintained. The same applies to the valve plug 150 of the valve port 20.

As described above, according to the valve plug 150 of the second embodiment, the valve body 52, which is pressed against the valve seat 60 to bring the high pressure passages 14 and 16 and the low pressure passages 17 and 18 into the closed state, is
Since it is slidably arranged in the recess 54 of the lid member 51, when the valve plug 50 is attached to the valve ports 20 and 21, the pressing force due to the screwing of the lid member 51 is transmitted to the valve body 52 and The cover member 51 is pressed against the seat 60.
Since the valve itself can slide on the outer peripheral surface of the valve body 52 independently of the valve body 52, tension for pulling the valve body 52 toward the lid member 51 is not applied and the valve body 52 is kept in the shut-off state. Since it can be pressed against the valve seat 60 with the best pressing force to maintain, the valve seat 60 is not destroyed.

When the directional control valve 1 is operated,
The oil pressure on the high-pressure passages 14 and 16 passes through the through holes 22 and 23, and the oil pressure on the high-pressure passages 14 and 16 changes to the valve body portion 5 of the valve body 52.
2B acts to push the valve seat 60 away from the valve seat 60, but since the lid member 51 is engaged with the end of the shaft portion 52A of the valve body 52, the valve body 52 does not move, and The valve body 52 and the valve seat 60 can be kept in the closed state.

[0054]

As described above, according to the valve plug of the first or fourth aspect of the present invention, the valve member that is pressed against the valve seat in order to disconnect the high pressure passage and the low pressure passage from each other is provided with the lid member. Since the lid member can be slid independently of the valve body when the valve plug is attached to the valve, even when the lid member is screwed, the lid member can be slidably attached as in the prior art. The tension that pulls the valve element toward the lid member is not applied, and the valve element can be pressed against the valve seat with the best pressing force to maintain the above-mentioned shut-off state, and the valve seat is not destroyed. .

Further, according to the first aspect, the elastic member is interposed between the lid member and the valve body, so that an error due to machining can be allowed.

According to the valve plug of the second aspect of the present invention, when the valve is operated, the oil pressure is introduced into the back pressure chamber through the passage of the valve body. Since the cross sectional area of the back pressure chamber passage is larger than the cross sectional area of the opening of the high temperature passage, the area between the pressure receiving area of the valve body on the high pressure passage side and the pressure receiving area of the valve body on the back pressure chamber side is large. Since a difference occurs, the combined force of the force that is introduced into the back pressure chamber and that acts on the valve element due to this area difference and the elastic force of the elastic body due to the rotation of the lid member when the valve plug is attached is from the high pressure passage side. As a result of overcoming the force acting on the valve body, the valve body will not be moved to the lid member side,
The valve body is not separated from the valve seat, and the shutoff state can be effectively maintained even when the valve is operating.

Further, according to the third aspect, by using an elastic body having a shorter axial length in the radial direction and a large spring coefficient, the shutoff state is maintained and the axial length of the valve plug is shortened. can do.

[Brief description of drawings]

FIG. 1 is a transverse cross-sectional configuration diagram showing an entire directional control valve using a valve plug according to a first embodiment of the present invention.

2A and 2B are views showing the configuration of the valve plug of Embodiment 1 in FIG. 1, in which FIG. 2A is a cross-sectional configuration diagram of the valve plug, FIG. 2B is a plan configuration diagram of the valve plug, and FIG. It is a horizontal block diagram of a spring washer.

FIG. 3 is a lateral cross-sectional view of a main part showing a procedure for mounting the valve plug of the first embodiment shown in FIG. 1 on a directional control valve.

FIG. 4 is a transverse cross-sectional view showing a configuration for operating a directional control valve to which the valve plug of the first embodiment in FIG. 1 is attached.

FIG. 5 is a transverse cross-sectional view showing a configuration for operating a directional control valve to which a valve plug of Example 2 of the present invention is attached.

FIG. 6 is a cross-sectional view of an essential part showing a valve plug of a conventional technique.

[Explanation of symbols]

 1 Direction switching valve (valve) 14, 16 High pressure passage 17, 18 Low pressure passage 50 Valve plug 51 Lid member 52 Valve body 53 Spring washer 56 Communication passage (passage) A Back pressure chamber

Claims (4)

[Claims] 1. A valve plug, wherein a valve seat is formed between a high pressure passage and a low pressure passage of a valve, and the valve seat is seated on the valve seat to constantly shut off the high pressure passage and the low pressure passage. A valve body, a lid member slidably fitted to the valve body and screwed to the valve, and a back pressure chamber defined between the valve body and the lid member. An elastic body and a passage that connects the back pressure chamber and the high-pressure passage to the valve body, and the elastic body prevents the valve seat from being broken and constantly presses the valve body. A valve plug having: 2. The valve plug according to claim 1, wherein the valve body and the back pressure chamber have a cross sectional area larger than an opening cross sectional area of the high pressure passage. 3. The valve plug according to claim 1, wherein the elastic body includes a disc spring, a spring washer, or a torsion bar. 4. A valve plug, wherein a valve seat is formed between a high pressure passage and a low pressure passage of a valve, and the valve seat is seated on the valve seat to constantly shut off the high pressure passage and the low pressure passage. And a lid member that is slidably fitted to the valve body and screwed to the valve.