JPH09133216A - Seal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal device by which a part of an O-ring is prevented from being broken by being forced out when a working condition is under high temperature and high pressure, and in which stable sealing properties can always be obtained even under high temperature and high pressure. SOLUTION: In a seal device 30 in which a seal ring 36 and an O-ring 37 are mounted in an annular recessed groove 35, a positioning groove 38 by which the O-ring 37 is positioned in the approximately center part of the seal ring 36 is formed to a contact surface with the O-ring 37 in the seal ring 36 so that the O-ring 37 is always guided to be fallen in the positioning groove 38.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sealing device,
In particular, the present invention relates to a sealing device that prevents fluid leakage between two members that reciprocate or rotate under high pressure.

[0002]

2. Description of the Related Art Conventionally, a sealing device 10 as shown in FIG. 7 has been known as a sealing device between two members that relatively reciprocate or rotate, such as a sealing device in a power steering system.

This sealing device 10 has a cylindrical surface 2
Cylindrical inner surface 2 of the outer first member 1 of the two members
An annular groove 5 provided on the cylindrical outer surface 4 of the inner second member 3, an O-ring 6 mounted on the annular groove 5, and an outer surface 7 in the annular groove 5 having the outer surface 7 as the first member 1 The seal ring 9 is in sliding contact with the inner surface 2 and the inner surface 8 is in sliding contact with the O-ring 6.

In such a sealing device 10, for example,
When the fluid pressure P is applied from the right side of the figure as shown in FIG. 8, the O-ring 6 moves to the left side of the figure by the pressure and elastically deforms itself.

Then, the force Ps due to this deformation is the contact surface forces P ₀ and P ₁ of the seal ring 9 and the O-ring 6 under no load.
In addition, the seal ring 9 is pressed against the sliding surface, that is, the inner surface 2 of the first member 1, so that the fluid can be sealed at a high pressure.

By the way, when the sealing device 10 is used under high pressure as described above, the side surfaces of the seal ring 9 and the O-ring 6 may come into close contact with the wall surface 11 of the annular groove 5. If this portion comes into close contact, when pressure is applied from the left side of the drawing in the next step, it is difficult for that pressure to be introduced to the inner O-ring 6 side, which causes the fluid pressure P to rise. As a result, the seal ring 9 is pushed away from the inner surface 2 of the first member 1 and a gap is created between the inner surface 2 of the first member 1 and the outer surface 7 of the seal ring 9, A so-called blow-through phenomenon occurs in which the pressure instantly escapes from this gap.

For the purpose of preventing such pressure blow-through phenomenon, a sealing device 20 having notches 12 on both side surfaces of a seal ring 9 as shown in FIG. 9 has also been proposed (for example, an actual flat plate 3-). 2964, etc.). By providing this notch 12, even when a close contact with the wall surface 11 occurs, the pressure applied from the side can be positively introduced to the inner O-ring 6 side through the notch 12. .

[0008]

However, when the notch 12 is provided in the seal ring 9 as described above, the O
When the ring 6 moves in the annular groove 5, as shown in FIG. 9, a part of the O-ring 6 may protrude into the notch 12. In particular, when such a sealing device 20 is used for power steering or the like, there is a problem that the protruding portion 14 is damaged by repeated use because the use condition is high temperature and high pressure. It was

Further, such protrusion causes eccentricity, vibration, etc. in the reciprocating second member 3. Then, the above-mentioned blow-through phenomenon reappears, and there is a problem in that the sealability of the seal ring 9 is impaired.

In view of the above situation, the present invention prevents blow-through of pressure from the sealing surface of the seal ring, and does not cause the O-ring to be damaged as in the case where a notch is provided in the seal ring, and the high temperature and high pressure Even if it is, it aims at providing the sealing device which can always obtain a stable sealing property.

[0011]

According to the present invention for achieving the above object, an annular groove is formed in a second member that reciprocates or rotates with respect to a first member, and a seal ring is formed in the annular groove. In a sealing device equipped with the O-ring and the O-ring, a positioning groove for locating the O-ring at a substantially central portion of the seal ring is formed on a contact surface of the seal ring with the O-ring.

[0012]

According to the present invention having the above-described structure, even when the O-ring moves in the annular groove, the O-ring is guided so as to always fall into the positioning groove provided at the substantially central portion of the seal ring. Therefore, it is possible to avoid a situation in which the O-ring is in close contact with the wall surface of at least the annular groove and does not separate. As a result, the O-ring is always located at the substantially central portion of the seal ring. Moreover, the O
The reaction force of the pressure that causes the ring to fall into the positioning groove is also transmitted to the seal ring, so that the seal ring is also separated from the wall surface of the annular groove.

Therefore, since the close contact with the annular groove is unlikely to occur, the pressure applied from the side is introduced to the O-ring side, and the seal ring is pressed outward, so that the seal ring has a stable sealing property. You can have it.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a sealing device according to an embodiment of the present invention, and particularly shows a sealing device used for power steering of an automobile.

In this sealing device 30, the second member 32 is arranged inside the first member 31, and the second member 3 is provided.
2 reciprocates on the inner surface 33 of the first member 31 by hydraulic pressure. An annular groove 35 is formed on the outer surface 34 of the second member 32, and a seal ring 36 and an O ring 37 are accommodated in the annular groove 35 in a slightly compressed state.

The seal ring 36 is made of fluorine resin or polyamide resin, and the O-ring 37 is made of synthetic rubber. In such a sealing device 30, a positioning groove 38 having an arcuate cross-section is formed in a substantially central portion of the seal ring 36. A part of the outer circumference of the O-ring 37 is fitted in the positioning groove 38. Therefore, when the O-ring 37 is in sliding contact with the seal ring 36, the O-ring 37 is guided so as to be positioned in the positioning groove 38, and is always arranged in the substantially central portion.

In such a sealing device 30, when the pressurized fluid is introduced into the chamber on the right side of the drawing and the second member 32 is pressed toward the left side of the drawing, the sealing ring 36 and the O-ring 37 are also drawn. The seal ring 36 and the O-ring 37 are pressed to the left in FIG.

At this time, the O-ring 37 moves by the fluid pressure P as shown by the chain double-dashed line in FIG.
As shown by the solid line, it returns into the central positioning groove 38.
That is, the highly elastic O-ring 37 deforms and comes into contact with the wall surface 39, but a part of the O-ring 37 still remains in the positioning groove 38. To do. Therefore, this O-ring 3
7 is not in close contact with the wall surface 39 while being in contact therewith.

On the other hand, in FIG. 2, the force for the O-ring 37 to return from the position indicated by the chain double-dashed line to the inside of the positioning groove 38 as indicated by the solid line also causes the seal ring 36 to move to the right in the figure. Since it acts, the seal ring 36 is also separated from the wall surface 39. Moreover, at this time, the annular groove 3
Since the O-ring 37 is deformed by the pressure introduced in 5, the pressure accompanying the deformation is applied to the seal ring 36, and the inner surface 33 of the first member 31 is pressed more strongly, so that the sealing performance is enhanced. It

On the other hand, when the pressure fluid is introduced into the chamber on the left side of the drawing from this state and the pressure fluid presses the second member 32 to the right side of the drawing, the same operation as above is performed. That is, in this case, the seal ring 37 is pressed rightward in the drawing by the pressure fluid. At that time, the O-ring 37 is already located in the positioning groove 38, and the seal ring 36 is also separated from the wall surface 39. From this state, when pressure fluid is applied from the left side of the drawing, the pressure fluid passes through the gap between the wall surface 39 and the seal ring 36, and the inner O-ring 37.
Introduced on the side. After that, when the O-ring 37 moves to the right in the drawing, it is considered that the O-ring 37 once comes into contact with the wall surface in the annular groove 35, but thereafter, the O-ring 37 is guided so as to fall into the positioning groove 38 again. Therefore, the O-ring 37 does not come into close contact with the wall surface of the annular groove 35. Moreover, since the force when the O-ring 37 falls into the positioning groove 38 acts on the seal ring 36, the seal ring 36 is consequently separated from the wall surface of the positioning groove 35.

Since it is difficult to visually observe the actual behavior of the O-ring 37 and the like in the sealing device 30 as described above, the seal ring behavior investigation device based on the principle shown in FIG. 3 is used. The effect was investigated.

The seal ring behavior investigation device will be described below. In this seal ring behavior device, the pressure detection passage 41 is formed in the annular groove 35 of the second member 32, and the working pressure is applied from the A side and left in that state for a predetermined time. The pressure P1 detected on the O-ring 37 side when the pressure is gradually increased from the side,
With this, the effect of introducing pressure to the O-ring 37 side is measured.

FIG. 4 shows an experimental result of measuring the sealing effect of the sealing device 30 of the embodiment using such a sealing behavior investigation device. Further, FIG. 5 shows an experimental result of measuring the sealing effect of the conventional sealing device 10 by using the seal ring behavior investigation device having the same principle.

According to the above, in the conventional sealing device 10, the pressure detected on the O-ring 6 side varies with respect to the operating pressure and the pressure standing time, and depending on the conditions, the O
In some cases, it was difficult to introduce pressure on the ring 6 side.

On the other hand, in the case of this embodiment, although the pressure P1 gradually increased with respect to the pressure standing time, there was almost no variation and the fluctuation of the detected pressure was small. From this, by providing the positioning groove 38, the O-ring 37 always tries to be located near the center of the positioning groove 38. Therefore, as shown by the arrow in FIG. It can be understood that the reaction force relatively prevents the seal ring 36 from closely contacting the wall surface of the annular groove 35 and facilitates introduction of pressure to the O-ring 37 side when pressure is applied from the opposite direction.

Further, according to the present embodiment, the seal ring 3
Since the side surface of 6 is not machined at all, there is no possibility that the O-ring will stick out due to the pressure unlike the cutout shape.

Further, since the seal ring 36 is usually formed by cutting a sleeve obtained by compressing and firing a raw material, automatic molding is possible even in such cutting. In the above embodiment, the second member 3 is used with respect to the first member 31.
Although the example in which the second member reciprocates is described as an example, the present invention can be applied to the case where the first member 31 reciprocates with respect to the second member 32.

Further, the present invention can be applied to a seal device between members that rotate instead of reciprocating, and further to a seal device between members that swing.

[0029]

As described above, according to the sealing device of the present invention, even when the O-ring moves in the annular groove, the O-ring is provided at the substantially central portion of the seal ring. Since it is guided so as to always fall into the positioning groove, it is possible to avoid the situation where the O-ring is stuck and does not separate from the wall surface of the annular recessed groove, and the O-ring is always located in the approximate center of the seal ring. become.

Therefore, no protruding portion is formed and the wall surface of the annular groove is unlikely to come into close contact, so that the pressure applied from the side is easily introduced to the O-ring side, and the pressure is applied. Since it is applied to the radially outer side and presses the seal ring outward, the seal ring can have a stable sealing property.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a sealing device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the operation of the sealing device according to the embodiment.

FIG. 3 is a sectional view of a behavior investigation device for investigating the action of the sealing device according to the embodiment.

FIG. 4 is a result of an experiment in which the sealing action according to the embodiment is investigated by using the behavioral investigation device shown in FIG.

5 is an experimental result as a comparative example of FIG. 4 in which a conventional example is investigated in the same manner as the principle of FIG.

FIG. 6 is a cross-sectional view illustrating how pressure is applied in the sealing device according to the embodiment of the present invention.

FIG. 7 is a cross-sectional view of a conventional sealing device.

FIG. 8 is a cross-sectional view illustrating how to apply pressure to an O-ring and a seal ring in this type of seal device.

FIG. 9 is a cross-sectional view showing the behavior of the O-ring when pressure is applied to another conventional sealing device.

[Explanation of symbols]

 30 Sealing device 31 1st member 32 2nd member 35 Annular groove 36 Seal ring 37 O-ring 38 Positioning groove

Claims (1)

[Claims] 1. A sealing device in which an annular groove is formed in a second member that reciprocates or rotates relative to the first member, and a seal ring and an O ring are mounted in the annular groove. On the contact surface of the seal ring with the O-ring,
A sealing device having a positioning groove for positioning the O-ring substantially at the center of the seal ring.