JPH08326924A - Lip packing and seal construction - Google Patents

Abstract

PURPOSE: To improve durability of a lip packing, and improve miniaturization and responsiveness of a product using the lip packing. CONSTITUTION: A lip packing 17 is mounted in a circumferential groove 16 provided on the outer circumference of a piston 13 slidable along a sliding face 21. The lip packing 17 is constituted of a base part 18, an inner circumferential lip part 19, and an outer circumferential lip part 20, and integratedly formed out of synthetic rubber. For preventing the lip packing from floating up by inner pressure between the inner circumferential lip part 19 and a bottom face 16a of the circumferential groove, a plurality of recessed parts 22 radially extending against the axis of the piston 13 are formed at regular intervals on the opposite face of the base part 18 to the side 16b of the circumferential groove. By the recessed parts 22, the inner pressure between the inner circumferential lip part 19 and the circumferential groove bottom face 16a can be released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lip packing and a seal structure using the lip packing.

[0002]

2. Description of the Related Art An annular lip packing is fitted in a circumferential groove formed on the outer circumference of a piston provided in a fluid pressure device such as a fluid pressure direction switching valve or a fluid pressure cylinder. An example of using U packing among the lip packings is shown in FIGS. 10 and 11.

That is, the U packing 41 has a base portion 42.
And an inner peripheral lip portion 43 extending from the base portion 42 to one side,
The inner peripheral lip portion 4 also extends from the base portion 42 to one side.
The outer peripheral lip portion 44 has a diameter larger than 3. The base portion 42, the inner peripheral lip portion 43, and the outer peripheral lip portion 44 are integrally formed of elastic synthetic rubber.

In the natural state of the U packing 41, the inner diameter thereof, that is, the diameter of the inner peripheral lip portion 43 on the inner peripheral side is smaller than the diameter of the bottom surface of the peripheral groove 46 of the piston 45 in which the U packing 41 is mounted. Has been formed. Also U
In the natural state of the packing 41, its outer diameter, that is, the diameter of the outer peripheral lip portion 44 on the outer peripheral side is formed larger than the diameter of the sliding surface 47 (the inner peripheral surface of the piston chamber) with which the U packing 41 is in sliding contact. . Therefore, when the U packing 41 is attached to the circumferential groove 46, the U packing 41 is compressed between the bottom surface 46 a of the circumferential groove 46 and the sliding surface 47, and the inner and outer surfaces of the U packing 41 are preloaded based on the compression. Are given respectively.

Then, as shown in FIG.
When the fluid pressure in the direction of arrow E is applied to 5, the base portion 42 of the U packing 41 is pressed against the circumferential groove side surface 46b. At the same time, the tip ends of the inner peripheral lip portion 43 and the outer peripheral lip portion 44 are elastically deformed so as to be expanded in a direction in which they are separated from each other. As a result, the base portion 42 applies pressure to the circumferential groove side surface 46b based on the fluid pressure, and the inner and outer lip portions 43 and 44 apply pressure to the sliding surface 47 and the circumferential groove bottom surface 46a, respectively. Therefore, the fluid pressure supplied to the chamber on the right side of the piston 45 is strongly sealed by the U packing 41.

[0006]

However, as shown in FIG.
When a fluid pressure in the direction of arrow E is applied to the piston 45, the fluid slightly leaks between the tip of the inner peripheral lip portion 43 and the bottom surface 46a of the circumferential groove as indicated by arrow F. The leaked fluid reaches between the inner peripheral lip portion 43 and the inner peripheral side of the base portion 42 and the peripheral groove bottom surface 46a.

On the other hand, as described above, the base portion 42 is pressed against the circumferential groove side surface 46b based on the fluid pressure applied to the right chamber, and the base portion 42 and the circumferential groove side surface 46b are firmly sealed. ing.

Therefore, when fluid pressure is applied to the chamber to the right of the piston 45, the U packing 41 and the circumferential groove 46
A closed pressure space K is formed between the space and. Since pressure is applied to the inner peripheral lip portion 43 of the U packing 41 from the right side, a pressing force acts on the inner peripheral lip portion 43 to the lower side and the left side in FIG. 10. Therefore, the internal pressure of the pressure space K acts in the upward direction of FIG. 10, that is, in the radial direction, as indicated by the arrow G. That is, the internal pressure of the pressure space K acts to lift the inner peripheral side of the U packing 41.

Due to the internal pressure of the pressure space K, the U packing 41 expands in the radial direction, and the U packing 41 floats from the bottom surface 46a of the circumferential groove 46, as shown in FIG. The floating phenomenon of the U packing 41 occurs even if the leak amount is extremely small even if the pressurization is performed for a long time.

When the floating phenomenon of the U packing 41 occurs, as shown in FIG. 11, the outer peripheral lip portion 44 and the outer periphery of the base portion 42 of the U packing 41 are largely elastically deformed and widely contact the sliding surface 47. The contact area between the U packing 41 and the sliding surface 47 is increased.

As a result, from the U packing 41 to the sliding surface 47
The vertical reaction force (the reaction force acting in the direction substantially orthogonal to the sliding direction of the piston 45) applied to the
Since the sliding resistance of No. 5 becomes large, the responsiveness of the piston 45 when fluid pressure is applied to the piston 45 deteriorates.

Therefore, in order to avoid the deterioration of the responsiveness of the piston 45, a method of setting the driving force of the piston 45 large can be considered. However, in order to increase the driving force of the piston 45, it is necessary to increase the pressure receiving area of the piston 45, which leads to an increase in the product size of fluid pressure equipment such as a directional control valve and a cylinder. Can't answer.

Further, as described above, the excessive vertical reaction force acts on the U packing 41, which increases the amount of wear of the U packing 41 and causes deterioration of the durability of the U packing 41.

The present invention has been made in order to solve the problems inherent in the lip packing as described above, and its purpose is to improve the durability of the lip packing and to use the lip packing. The aim is to reduce the size of products and improve responsiveness.

[0015]

In order to achieve the above object, the invention according to claim 1 comprises a base portion, an inner peripheral lip portion extending from the base portion, and an outer peripheral lip portion extending from the base portion. In the lip packing to be mounted, a concave portion or a convex portion for forming a passage for releasing internal pressure between the inner peripheral lip portion and the bottom surface of the peripheral groove is provided on the surface of the base portion facing the side surface of the peripheral groove.

The invention according to claim 2 is a seal structure in which a lip packing having a base portion, an inner peripheral lip portion extending from the base portion, and an outer peripheral lip portion extending from the base portion is mounted in a peripheral groove. A passage for releasing internal pressure between the lip portion and the bottom surface of the circumferential groove is provided between the opposing surfaces of the base portion and the side surface of the circumferential groove.

According to a third aspect of the present invention, in the seal structure according to the second aspect, the passage is a recess formed in at least one of the surfaces of the base portion and the circumferential groove side surface facing each other. It is composed of convex portions.

According to a fourth aspect of the present invention, in the seal structure according to the second aspect, the passage is formed by a through hole that is open on a side surface of the peripheral groove toward a bottom surface of the peripheral groove.

[0019]

In the conventional structure, in the pressurized state, the inner peripheral seal portion and the bottom surface of the peripheral groove are pressed into contact with each other, and the side surface of the peripheral groove and the base portion are pressed into contact with each other to form a pressure space. The lip packing expands in the radial direction,
The phenomenon of floating from the bottom of the circumferential groove occurs.

However, according to the present invention, a concave portion or a convex portion is provided on at least one of the facing surfaces of the base portion and the side surface of the circumferential groove, or a through hole is formed which opens on the side surface of the circumferential groove near the bottom surface of the circumferential groove. By this means, a passage is formed between the inner peripheral lip portion and the bottom surface of the peripheral groove for releasing the internal pressure.

Therefore, the above-mentioned generation of the pressure space is suppressed, the radial expansion of the lip packing is eliminated, and the floating phenomenon of the lip packing from the bottom surface of the circumferential groove is reliably prevented.

As a result, it is possible to prevent the outer peripheral lip portion and the base portion from being largely elastically deformed and widely contacting the sliding surface, thereby preventing the contact area between the lip packing and the sliding surface from increasing. Further, it is possible to maintain the state in which the vertical resistance applied from the lip packing to the sliding surface is small, and to suppress the sliding resistance to be small. This is extremely important for improving the durability of the lip packing and preventing deterioration of responsiveness of the piston or the like to which the lip packing is mounted. In addition, since it is possible to prevent deterioration of responsiveness of the piston in this way, it is not necessary to take measures to increase the product size, such as increasing the pressure receiving area of the piston.
This leads to product miniaturization.

[0023]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 3 shows a cross section of a pilot type two-position five-port type pilot type fluid pressure directional control valve 1. The directional control valve 1 is composed of a valve body 2 and an electromagnetic solenoid section 3. A spool chamber 4 is formed inside the valve body 2, and the spool chamber 4 is connected to the outside through input ports P, output ports A and B, and exhaust ports R1 and R2. In the spool chamber 4, each port P,
A valve seat 5 is formed between each of A, B, R1 and R2. A spool valve 6 is accommodated in the spool chamber 4 so as to be movable in the left-right direction. The spool valve 6 is formed with a plurality of flange-shaped packing mounting portions 7, and each packing mounting portion 7 is formed with a circumferential groove 8 in the circumferential direction thereof. An annular O-ring 9 is mounted in each circumferential groove 8. Each O-ring 9 slides on each valve seat 5 as the spool valve 6 reciprocates.

The electromagnetic solenoid section 3 includes an exciting coil 10
There are provided a plunger 11 which is driven by, a piston 13 which is housed in a piston chamber 12, and which is connected to the spool valve 6 and has a circular cross section. A part of the fluid supplied to the input port P is supplied to the piston chamber 12 as a pilot fluid. Then, when the exciting coil 10 is not energized, the plunger 11 is arranged on the left side by the return spring 14. In this case, the pilot fluid is not introduced into the piston chamber 12, and the piston 13 is returned to the piston chamber 12 by the return spring 15.
It is located at the right end of. Piston 13 is piston chamber 1
2 is located at the right end of the spool valve 6 at the same time.
Is located at the right end of the spool chamber 4, the input port P
Is the output port A, the output port B is the exhaust port R2,
It is designed to communicate with each other.

When the exciting coil 10 is energized, the plunger 11 is driven to protrude to the left. At this time, piston chamber 1
Since the pilot fluid is introduced to the right of 2, the piston 13 is moved to the left end of the piston chamber 12. Therefore, the spool valve 6 is moved to the left end of the spool chamber 4, and the input port P communicates with the output port B and the output port A communicates with the exhaust port R1. The space to the left of the piston 13 in the piston chamber 12 is in communication with the atmosphere via a flow passage formed in the valve body. Therefore, the space to the left of the piston 13 in the piston chamber 12 is always kept at atmospheric pressure.

As shown in FIGS. 1 and 3, the piston 13
A peripheral groove 16 is formed on the outer periphery of the. This circumferential groove 1
6 is composed of a bottom surface 16a and a side surface 16b. An annular U packing 17 as a lip packing is attached to the circumferential groove 16. That is, U packing 1
Reference numeral 7 denotes an annular base portion 18, an annular inner peripheral lip portion 19 extending from the base portion 18 to one side, and an annular outer peripheral portion also extending from the base portion 18 to one side and having a diameter larger than the inner peripheral lip portion 19. A lip portion 20, and these base portions 18,
The inner peripheral lip portion 19 and the outer peripheral lip portion 20 are integrally formed of elastic synthetic rubber (nitrile rubber in this embodiment).

In the natural state (non-pressurized state) of the U packing 17, its inner diameter, that is, the inner peripheral lip portion 1
The diameter of the inner circumferential side of 9 is smaller than the diameter of the bottom surface of the circumferential groove 16 of the piston 13. Also, U packing 17
In the natural state, the outer diameter thereof, that is, the diameter of the outer peripheral lip portion 20 on the outer peripheral side is formed larger than the diameter of the sliding surface 21 (the inner peripheral surface of the piston chamber 12) with which the U packing 17 slides.

Therefore, when the U packing 17 is attached to the circumferential groove 16, the U packing 17 is compressed between the bottom surface of the circumferential groove 16 and the sliding surface 21, and the inner and outer surfaces of the U packing 17 are compressed. The preload is based on each.

As shown in FIGS. 1 and 2, on the surface of the base portion 18 opposed to the side surface of the circumferential groove 16, eight concave portions 2 extend radially with respect to the axis of the piston 13 and are spaced at predetermined intervals.
2 is formed. Then, the concave portion 2 of the U packing 17
A passage T is formed by the space surrounded by 2 and the side surface 16 b of the circumferential groove 16.

Next, the operation of the first embodiment constructed as described above will be described. FIG. 3 shows a state in which the pilot fluid is not supplied to the piston chamber 12, and in this state, the return spring 15 holds the spool valve 6 and the piston 13 at the right end position. At this time, the input port P and the output port A are in communication, and the exhaust port R2 and the output port B are in communication.

Here, when the spool valve 6 is switched so that the input port P and the output port B are communicated with each other and the exhaust port R2 and the output port A are communicated with each other, the exciting coil 10 is energized, The plunger 11 projects leftward against the urging force of the return spring 14, and the pilot fluid is supplied to the piston chamber 12. Due to this fluid pressure, the piston 13 moves to the left side against the biasing force of the return spring 15, and the ports connected as described above are switched.

Pilot fluid pressure is applied to the right side of the piston 13, and atmospheric pressure is applied to the left side thereof. The state of the U packing 17 at this time will be described in detail.
As shown in FIG. 1, the U packing 17 has its base portion 18 pressed against the circumferential groove side surface 16b by the fluid pressure applied in the direction of the arrow E. At the same time, the tip ends of the inner peripheral lip portion 19 and the outer peripheral lip portion 20 are elastically deformed so as to be spread apart in the direction in which they are separated from each other. As a result, the base portion 18 applies pressure based on the fluid pressure to the circumferential groove side surface 16b, and the inner and outer lip portions 19 and 20 apply pressure based on the fluid pressure to the sliding surface 21 and the circumferential groove bottom surface 16a, respectively. Therefore, the fluid pressure applied from the right side of the piston 13 is applied to the U packing 1
7 provides a strong seal.

When fluid pressure is applied from the right side of the piston 13, as shown by an arrow F in FIG.
A small amount of fluid leaks from between the tip of 9 and the bottom surface 16a of the circumferential groove. The leaked fluid flows from the inner peripheral lip portion 19 toward the inner peripheral side of the base portion 18 to the bottom surface 16a of the peripheral groove.
Reach between and.

In this embodiment, the circumferential groove side surface 16b of the base 18 is
Eight recessed portions 22 are formed on the surface facing to and extending radially with respect to the axis of the piston 13 and at predetermined intervals. Then, the concave portion 22 of the U packing 17 and the circumferential groove side surface 1
A passage T is formed by the space surrounded by 6b.

In the passage T, the fluid leaked from the inner peripheral lip portion 19 to the inner peripheral side of the base portion 18 between the peripheral groove bottom surface 16a and the peripheral groove bottom surface 16a is shown to the left of the piston 13, that is, as shown by an arrow H. It acts to guide to the atmospheric pressure side.

In the prior art, the U packing 41 was expanded by the internal pressure of the pressure space K (see FIGS. 10 and 11). In this embodiment, the portion corresponding to the pressure space K is atmospheric pressure. Because it is in communication, the inner lip 1
From 9 to the inner peripheral side of the base portion 18, the space between the peripheral groove bottom surface 16a and the peripheral groove bottom surface 16a is maintained at atmospheric pressure.

As a result, the pressure of the fluid leaked from between the tip of the inner peripheral lip portion 19 and the bottom surface 16a of the peripheral groove does not act to lift the inner peripheral side of the U packing 17, and the U packing 17 is radially moved. Is prevented from spreading. Further, the outer peripheral lip portion 20 of the U packing 17 and the base portion 1
8 The outer circumference does not elastically deform due to the internal pressure of the leaked fluid and widely contacts the sliding surface 21.

Therefore, it is possible to prevent the contact area between the U packing 17 and the sliding surface 21 from increasing, and also prevent the normal force applied from the U packing 17 to the sliding surface 21 to increase. can do.

As a result, the sliding resistance of the piston 13 can be suppressed small, and the responsiveness of the piston 13 when a fluid pressure is applied to the piston 13 can be improved. Further, since the responsiveness of the piston 13 is good, it is not necessary to set the driving force of the piston 13 to be large, and the pressure receiving area of the piston 13 can be made small.
The piston 13 and the piston chamber 12 can be downsized, and the directional control valve 1 can be downsized.

Further, as described above, since an excessive vertical reaction force does not act on the U packing 17, the amount of wear of the U packing 17 is reduced and the durability of the U packing 17 can be improved.

Further, in the present embodiment, the passage T for letting the leaked fluid escape to the atmosphere is radially extended with respect to the U packing 17 with respect to the axis of the piston 13, and the recesses 22 are provided at predetermined intervals. ing. Therefore, the leaked fluid can be evenly released from the plurality of passages T, and an unbalanced load is not applied to the U packing 17.

Furthermore, since the recess 22 is integrally formed when the U packing 17 is manufactured, the manufacturing is not difficult as compared with the conventional U packing. (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The same applies to the following embodiments.

Unlike the first embodiment, the U packing 17 as the lip packing of the second embodiment has no recess 22 formed therein. A concave portion 31 is formed on the side surface 16b of the circumferential groove 16 that faces the base portion 18 and connects the bottom surface 16a of the circumferential groove 16 and the outer peripheral end. This recess 31 is
Eight pieces are formed on the circumferential groove side surface 16b radially at equal intervals with the axis of the piston 13 as the center.

Therefore, the passage T is formed by the space surrounded by the recess 31 and the base 18. This passage T
Guides the fluid leaking from the inner peripheral lip portion 19 to the inner peripheral side of the base portion 18 to the peripheral groove bottom surface 16a to the left of the piston 13, that is, the atmospheric pressure side.

Also in the second embodiment, the same action and effect as those of the first embodiment can be obtained, and the U packing which has existed in the past can be used as it is, which is excellent in versatility. .

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, a convex portion 32 is formed instead of forming the concave portion 22 in the U packing 17 as the lip packing in the first embodiment.
Eight convex portions 32 also extend radially with respect to the axis of the piston 13 and are formed at predetermined intervals.

The passage T is formed by the space surrounded by the peripheral groove side surface 16b and the portion of the base portion 18 of the U packing 17 where the convex portion 32 is not formed. Also in the third embodiment, the same operation and effect as those of the first embodiment can be obtained.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, a convex portion 33 is formed instead of forming the concave portion 31 on the side surface 16b of the circumferential groove 16 in the second embodiment. Eight convex portions 33 also extend radially and are formed at predetermined intervals.

Then, a portion of the side surface 16b of the circumferential groove 16 where the convex portion 33 is not formed and the base portion 1 of the U packing 17.
A passage T is formed by the space surrounded by 8 and.
Also in the fourth embodiment, the same operation and effect as in the second embodiment can be obtained.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIG. In the fifth embodiment, instead of forming the concave portions 22 radially on the surface of the base portion 18 facing the circumferential groove side surface 16b in the first embodiment, the bottom surface 16a is formed on the surface of the base portion 18 facing the circumferential groove side surface 16b from the bottom surface 16a. A concave portion 34 extending in a quadratic curve is formed toward the outer end side of the side surface 16b. Four recesses 34 are formed at a predetermined interval.

The passage T is formed by the space surrounded by the recess 34 and the side surface 16b of the circumferential groove. This fifth
Also in the embodiment, the same operation and effect as in the first embodiment can be obtained.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described with reference to FIG. In the sixth embodiment, the concave portions 22, 31, 34 or the convex portions 32, 33 are the same as in the above embodiments.
Instead of providing the above, the through hole 35 communicating with the bottom surface 16a of the circumferential groove side surface 16b and the left side of the piston 13 is formed in the piston 13. In addition, this through hole 35 is 1
Although only one is shown, it is actually provided at eight locations at equal intervals.

The passage T is formed by the through hole 35. Also in the sixth embodiment, the same operation and effect as in the second embodiment can be obtained. Further, as in the above-mentioned respective embodiments, the concave portions 22, 31, 34 or the convex portions 32,
It is easier to manufacture than providing 33, and moreover, the through hole 35 can be easily formed even in an existing piston.

The present invention is not limited to the above embodiment, but may be configured as follows. (1) Base 18 of lip packing 17 or side surface 16 of circumferential groove
Although the convex portion 32, 33 is integrally formed in b is illustrated, the convex portion 32, 33 may be separately manufactured and integrated by adhesion or the like.

(2) Convex portions 32, 33, concave portions 22, formed on the base portion 18 of the lip packing 17 or the side surface 16b of the peripheral groove,
The number of 31, 34 or the through holes 35 need not be 4 or 8 as in each of the above-described embodiments, but may be 1 or more. It is not always necessary to provide a plurality of holes at equal intervals. .

(3) Convex portions 32 and 33, concave portions 22 and 31,
34 or the through-hole 35, the U packing 17 and the circumferential groove bottom surface 16
The shape may be any shape as long as the internal pressure between a and can be released.

(4) In order to form the passage T, the protrusions 32, 32 are formed on the base portion 18 of the lip packing 17 or the side surface 16b of the circumferential groove.
33, the concave portions 22, 31, 34 or the through holes 35 are provided as various examples, but other than this, for example, another member may be interposed between the base portion 18 of the lip packing 17 and the circumferential groove side surface 16b. The passage T may be configured. As the other member, for example, a tubular member or a non-flat member capable of forming the passage T in cooperation with the base portion 18 of the lip packing 17 or the circumferential groove side surface 16b can be considered.

(5) The recess 2 is formed in the base 18 of the U packing 17.
2, 34 or the convex portion 32 is provided, and the circumferential groove side surface 16b is provided.
The concave portion 31, the convex portion 33, or the through hole 35 may be provided in the.

(6) Although only the U packing 17 is illustrated as an example of the lip packing, the lip packing of the present invention naturally includes what is generally called V packing or Y packing.

(7) In the above embodiment, the lip packing 17 mounted on the piston 13 in the directional control valve 1 is illustrated, but the packing mounted on the spool valve 6 in the directional control valve 1 is embodied, or the fluid pressure is changed. Other fluid pressure devices such as cylinder pistons may be embodied.
The fluid pressure may be pneumatic pressure or hydraulic pressure.

(8) In the second and fourth embodiments, the concave portion 31 or the convex portion 33 provided on the circumferential groove side surface 16b of the piston 13 may be configured such that the corners thereof have a smooth shape. . According to this configuration, the concave portion 31 or the convex portion 33
The U packing 17 is prevented from being damaged by the corner portions of the U packing 17, and the damage to the U packing 17 due to the damage can be prevented.

The technical ideas other than the claims that can be understood from the above-described embodiments will be described below along with their effects. (1) In the lip packing or the seal structure according to claim 1 or 3, the convex portion is formed integrally with the base portion.
According to this structure, the production of the lip packing does not become more complicated than the conventional one.

(2) In the lip packing according to the first aspect or the seal structure according to the third aspect, a plurality of concave portions or convex portions are provided at predetermined intervals. Further, in the seal structure according to the fourth aspect, a plurality of through holes are provided at predetermined intervals. According to these configurations, the internal pressure between the inner peripheral lip portion and the bottom surface of the peripheral groove can be uniformly released.

(3) In a fluid pressure device (direction switching valve, cylinder, etc.) in which the piston is slidable on the sliding surface of the inner circumference of the body, a circumferential groove is formed on the outer circumference of the piston, and a lip is formed on the circumferential groove. A packing is attached, the lip packing is a base portion, an inner peripheral lip portion extending from the base portion and at least a tip side of which is pressed against the bottom surface of the circumferential groove, and an outer peripheral lip portion extending from the base portion and at least a tip side of which is pressed against a sliding surface. Consisting of
A passage for releasing the internal pressure between the inner peripheral lip part and the bottom of the peripheral groove,
Sealing structure for fluid pressure equipment provided on the surface facing the base and the side surface of the circumferential groove. With this configuration, it is possible to prevent the lip packing from rising from the circumferential groove in a fluid pressure device such as a directional control valve or a cylinder.

[0066]

As described in detail above, according to the present invention,
It is possible to improve the durability of the lip packing, and it is possible to reduce the size of the product using the lip packing and improve the responsiveness.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a state in which a lip packing is installed in a circumferential groove according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the lip packing.

FIG. 3 is a sectional view of the pilot type fluid pressure directional control valve.

FIG. 4 is a partial cross-sectional view showing a state in which a lip packing is installed in a circumferential groove according to the second embodiment.

FIG. 5 is a perspective view of the piston.

FIG. 6 is a perspective view of a lip packing according to the third embodiment.

FIG. 7 is a perspective view of a piston according to the fourth embodiment.

FIG. 8 is a perspective view of a lip packing according to the fifth embodiment.

FIG. 9 is a partial cross-sectional view showing a state in which a lip packing is attached to the circumferential groove according to the sixth embodiment.

FIG. 10 is a partial cross-sectional view showing a state in which a lip packing is attached to a circumferential groove according to a conventional example.

FIG. 11 is a partial cross-sectional view showing a state in which lip packing is also mounted in the circumferential groove.

[Explanation of symbols]

13 ... Piston, 16 ... Circumferential groove, 16a ... Bottom surface of peripheral groove, 1
6b ... Side surface of peripheral groove, 17 ... U packing as lip packing, 18 ... Base part, 19 ... Inner peripheral lip part, 20 ... Outer peripheral lip part, 21 ... Sliding surface, 22, 31, 34 ... Recessed part, 3
2, 33 ... convex portion, 35 ... through hole, T ... passage.

Claims (4)

[Claims] 1. A base (18), an inner peripheral lip (19) extending from the base (18), and an outer peripheral lip (20) extending from the base (18), which is mounted in the peripheral groove (16). In the lip packing, a concave portion (22, 3) for forming a passage (T) between the inner peripheral lip portion (19) and the peripheral groove bottom surface (16a) for releasing the internal pressure.
4) or the convex portion (32), the side surface (1) of the circumferential groove of the base portion (18).
6b) provided on the surface facing the lip packing. 2. A lip packing (17) comprising a base (18), an inner peripheral lip (19) extending from the base (18) and an outer peripheral lip (20) extending from the base (18).
In the sealing structure in which the peripheral groove (16) is mounted, the passage (T) between the inner peripheral lip portion (19) and the bottom surface (16a) of the peripheral groove is provided with the base portion (18) and the peripheral groove side surface (1).
6b) is provided between the opposing surfaces of the seal structure. 3. The seal structure according to claim 2, wherein
Through the passage (T), the base (18) and the circumferential groove side surface (16b)
A seal structure comprising a concave portion (22, 31, 34) or a convex portion (32, 33) formed on at least one of the surfaces facing with. 4. The seal structure according to claim 2,
The passage (T) is formed on the bottom surface (1) of the circumferential groove on the side surface (16b) of the circumferential groove.
6b) A seal structure comprising a through hole (35) opening toward the side.