JP2002276814A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a durability by effectively preventing a projection of a seal body at high pressure without increasing a cost and an installment space. SOLUTION: A projection 22 contacted with a corner part 32b of a mounting groove 32 of one member 3 is formed on an end surface 2a of a backup ring 2. The backup ring 2 is inclined with a good responsiveness making the projection 22 as a fulcrum by an axial load F from the seal body receiving a pressure and a gap δ1 between the backup ring 2 and the other member 4 is shrunk. Therefore, the projection of the seal body to this gap δ1 and a 'bitten' caused by this are effectively prevented. In the case where a pressure rise is relatively large, the gap δ1 is buried by falling down of the projection 22 and displacing the backup ring 2 to the other member 4 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device which seals a space between two members which are concentrically arranged and move relatively to each other, and more particularly to a sealing device which is mounted in a mounting groove of one of the members so that the air space side is closed. The back surface of the facing seal body is supported via a backup ring.

[0002]

2. Description of the Related Art Conventionally, as a sealing device provided between a housing and a piston or rod, such as a hydraulic cylinder or a shock absorber, as shown in FIG. 8, is known. FIG. 8 is a half sectional view showing a state in which a sealing device according to a conventional technique is used as a rod seal, cut along a plane passing through an axis.

That is, this type of sealing device is made of an elastic material such as rubber, and has a seal lip 10 at an inner peripheral portion and an outer peripheral portion.
1 and 102, and a backup ring 110 arranged on the back side of the seal body 100 (the side opposite to the seal lips 101 and 102). It is mounted in the groove 121 in a housed state. Seal body 100
Is mounted so that the seal lips 101 and 102 face the pressure introduction space _SH side where the pressure is increased by pressure introduction.
The outer peripheral seal lip 101 is the bottom surface 121a of the mounting groove 121.
Together closely, the inner periphery seal lip 102 is slidably and closely, for example, in the outer peripheral surface of the axially reciprocably inserted rods 130 inner periphery of the housing 120, a pressure introducing space S _H and the atmosphere side space carry out the sealing between the S _L.

[0004] The material of the backup ring 110 is made of a relatively soft material such as PTFE (polytetrafluoroethylene) as a base material and a relatively hard thermoplastic resin such as polyamide resin (trade name: nylon). It is roughly divided into In addition, since it is necessary to set a tolerance that allows a certain gap to the cross section CS for the purpose of assembling to the mounting groove 121, in the initial state, the diameter between the cross section CS and the outer peripheral surface of the rod 130 is smaller. there are direction gap [delta] _1.

[0005] Figure 9 is a state in which high pressure is applied from the pressure introduction space S _H in use, it is a half cross-sectional view taken in a plane passing through an axis. That is, when the pressure introduction space _SH becomes high due to the introduction of hydraulic pressure or the like, the pressure causes the seal body 100 to attach the backup ring 110 to the mounting groove 12.
Because pressing the 1 atmosphere side space S _L side wall 121b, extend radially deformed with backup ring 110 is compressed and deformed in the axial direction, thereby reducing the gap [delta] _1,
Inner peripheral corner 103 on the back surface of seal body 100
Is the gap δ ₂ between the housing 120 and the rod 130.
To prevent breakage, which is called "eating".

[0006]

According to the invention It is an object of the above prior art, which the backup ring 110 is made of PTFE-based material is relatively because it is soft, the pressure rise in the pressure introduction space S _H is relatively small also, although the gap [delta] ₁ and easily extended radially deformed can fill some extent, on the other hand, there is a problem of poor pressure resistance. Therefore, when the pressure increase in the pressure introduction space _{S H} is large, the backup ring 110 itself, the housing 120 and the rod 13
There is a risk of breakage by protruding into the gap δ ₂ between
Not suitable for high pressure conditions. Further, PTFE has a high material price and a high processing cost.

On the other hand, when the backup ring 110 is made of a thermoplastic resin such as a polyamide resin, it is relatively hard and therefore has excellent pressure resistance, and therefore, the gap δ ₂ between the housing 120 and the rod 130. However, on the other hand, since the deformability when the pressure introduction space _SH becomes high pressure is poor, the seal body 10
0 is pressed in a slightly reduced clearance [delta] ₁ due to the back-up ring 110 is extended, in particular, when seal body 100 is, for example, made of excellent NBR (nitrile rubber) or the like in oil resistance, NBR is for rich in deformability, the corners 103 of the seal body 100 will protrude into the gap [delta] _1, which may cause "erosion". As a countermeasure, the backup ring 110, it is conceivable to keep as small as possible the clearance [delta] ₁ from an initial state in which the pressure in the pressure introduction space S _H does not act, in this case mounting groove 121 and the backup ring 110 It is necessary to tighten the dimensional tolerance in the radial direction, and there is a limit in terms of processing cost and productivity.

Further, as the corners 103 of the seal body 100 is to prevent a problem protrude on the inner peripheral clearance [delta] ₁ of the backup ring 110 is another example of a sealing device according to the prior art in FIG. 10 is shown It is conceivable to use a relatively soft PTFE-based backup ring 110A and a relatively hard backup ring 110B made of a thermoplastic resin such as a polyamide resin in this case. Rising,
There is a problem that the mounting space increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its technical object to effectively protrude a seal body under high pressure without increasing cost and mounting space. And to increase its durability.

[0010]

As a means for effectively solving the above-mentioned technical problem, a sealing device according to the first aspect of the present invention is provided with a sealing member provided in one of two members concentrically arranged. A seal body mounted in the formed annular mounting groove and slidably in contact with the other member; and a backup ring disposed on the low pressure side of the seal body in the mounting groove. And a projection which is in contact with the corner or an end face near the corner.

Further, the sealing device according to the second aspect of the present invention,
According to the first aspect of the present invention, the protrusion falls down to the corner of the mounting groove by an axial load equal to or more than a predetermined value to displace the backup ring toward the other member.

Further, the sealing device according to the third aspect of the present invention,
In the invention of claim 1 or 2, the axial thickness of the backup ring H, the radial width T, When the gap [delta] ₁ between the backup ring and the other member, the projection height h
H = δ ₁ · T / H

[0013] The sealing device according to the invention of claim 4 is:
A seal body mounted in an annular mounting groove formed in one of the two members concentrically arranged and slidably contacted with the other member; and a low pressure side of the seal body in the mounting groove. A backup ring to be disposed, wherein a projection is formed on the backup ring to elastically contact the bottom surface and urge the backup ring toward the other member.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a sealing device according to the present invention will be described below with reference to the drawings. FIG. 1 is a half sectional view showing a first embodiment in which a sealing device according to the present invention is used as a rod seal, cut along a plane passing through an axis, and FIG. 2 shows a backup ring constituting the sealing device. It is sectional drawing cut | disconnected and shown by the plane which passes an axis.

First, in FIG. 1, reference numeral 3 denotes a housing as one member, which corresponds to, for example, a rod cover in a hydraulic cylinder device or the like. Reference numeral 4 denotes a rod as the other member, which is inserted through the inner periphery of the housing 3 concentrically and reciprocally in the axial direction. The inner peripheral surface 31 of the housing 3 is formed with an annular mounting groove 32 that is continuous in the circumferential direction. The sealing device according to this embodiment includes the seal body 1 and the backup ring disposed in the mounting groove 32. 2

The seal body 1, which has been molded with an elastic material such as rubber, that is, the inner peripheral portion thereof and the outer peripheral portion, the circle facing the pressure introducing space S _H of the cylinder interior becomes a high-pressure A pair of circumferentially continuous seal lips 11, 1
2, the outer peripheral surface near the distal end of the outer peripheral seal lip 11 is in close contact with the bottom surface 32a of the mounting groove 32, and the inner peripheral surface near the distal end of the inner peripheral seal lip 12 is on the outer peripheral surface of the rod 4. by closely slidably and separates the pressure introducing space S _H, and the atmosphere side space S _L.

The backup ring 2 is formed in a flat annular shape using a relatively hard thermoplastic resin such as a polyamide resin, for example.
Is formed to have the same diameter as or slightly smaller than the bottom surface 32a of the rod 4, and the inner diameter is formed slightly larger than the outer diameter of the rod 4. Therefore, the radial width T of the backup ring 2 is slightly smaller than the cross section CS between the bottom surface 32a of the mounting groove 32 and the outer peripheral surface of the rod 2, and in the initial state, the backup ring 2 between the inner circumferential surface and the rod 2, a gap [delta] ₁ is present. Further, as shown in FIG. 2, the backup ring 2 can be reduced in diameter by having a cut portion 21 at one location in the circumferential direction, and thereby, the inner peripheral surface 31 of the small-diameter housing 3 can be displaced. From above, it can be inserted into the mounting groove 32.

Both end faces 2a, 2b of the backup ring 2
Are formed at the outer peripheral end portions thereof in the form of protrusions 22 which are annularly continuous in the circumferential direction.
2 is a corner 3 on the low pressure side in the mounting groove 32 of the housing 3
2b. When the protrusion 22 is formed only on one end surface, in order to make it contact the corner 32b, it is necessary to consider the direction of the protrusion 22 when inserting the protrusion 22 into the mounting groove 32. In the illustrated embodiment, since it is provided on both end surfaces 2a and 2b, it is not necessary to consider the mounting direction.

FIG. 3 is an enlarged partial sectional view showing the projection 22 and its vicinity. As shown in FIG. 3, the protrusion 22 has an outer peripheral surface 22 a formed on the backup ring 2.
Is flush with the outer peripheral surface 2c, and the inner peripheral surface 22b is the tip 22c.
The tapered shape gradually increases in diameter toward. For this reason, when an axial compressive load is received, as shown by a dashed line in the figure, the diaper is deformed so as to fall to the outer peripheral side.

The height h of the protrusion 22 in the axial direction is as follows: h = δ ₁ · T / H (1) H is the thickness of the backup ring 2 in the axial direction. Also preferably, the inner peripheral surface 22 of the projection 22
The radial projection height h ′ of the projection 22 when b falls down until it is substantially flush with the end face 2 a of the backup ring 2.
But so that the initial clearance [delta] ₁ is substantially equal.

FIG. 4 is an explanatory view showing the operation of the present invention with the seal body 1 omitted. That is, the configured sealing device as described above, in the initial state in which the operating pressure in the pressure introducing space S _H not introduced, as shown in Fig. (A), the backup ring 2, the outer peripheral surface 2c in contact with the bottom surface 32a of the mounting groove 32 of the housing 3, projection 22 is in contact with the atmosphere side space _{S L} side corner portion 32b of the mounting groove 32, the end face 2a facing the air-side space _{S L} side
Are in a non-contact state with the end face 32 c of the mounting groove 32, and a gap δ ₁ is formed between the inner peripheral face 2 d of the backup ring 2 and the outer peripheral face of the rod 4.

Next, by operating the pressure by the hydraulic or the like is introduced into the pressure introducing space S _H, the pressure introducing space S
When _H is high than the atmospheric side space S _L, the seal body for receiving the pressure, the backup ring 2 is pressed toward the end face 2a of the atmosphere-side space S _L side in the mounting groove 32, and FIG. 4 (B) as shown in, inclined projection 22 as a fulcrum, the inner peripheral portion 2a of the end face 2a facing the air-side space S _L 'side is in contact with the inner peripheral edge of the end face 32c of the mounting groove 32. Therefore, the gap [delta] ₁ between the inner and outer circumferential surfaces of the rod 4 of the backup ring 2 is reduced in pressure introducing space S _H side (seal body).

Here, assuming that the inclination angle of the backup ring 2 in the state shown in FIG.
Is represented by h ≒ T tan θ (2), so that tan θ = h / T (3). On the other hand, the size of the gap [delta] ₁ is because represented by _{δ 1 = Htanθ ... (4)} tanθ = δ 1 / H ... (5). That is, from the above equations (3) and (5), h / T = δ ₁ / H (6), so that the height h of the protrusion 22 is set as in the above equation (1). When the backup ring 2 is tilted to the state shown in FIG. 4B, between the end 2 d ′ of the pressure introduction space _SH side (the seal body side) in the inner peripheral surface 2 d and the outer peripheral surface of the rod 4. In this case, the gap δ ₁ becomes substantially zero.

Further, since the projection 22 serving as a fulcrum is located at the outer peripheral end of the backup ring 2, the inclination displacement of the backup ring 2 as described above can be performed even if the axial pressing load F from the seal body is small. Responsive. Thus even with a small pressure rise in the pressure introducing space S _H, it is ensured by filling the gap [delta] _1, protruding on the inner circumferential side of the corner 13 at the rear surface of the seal body 1 and due to this called "Erosion" Damage can be prevented from occurring.

[0025] Then, by the pressure of the pressure introducing space _{S H,}
Pressing load F from seal body 1 to backup ring 2
Is further raised, the projection 22 falls along the outer periphery as shown in FIG. 4 (C). this is,
As shown in FIG. 3, the outer peripheral surface 22 a of the projection 22 is flush with the outer peripheral surface of the backup ring 2, and the inner peripheral surface 2 a
This is because 2b has a tapered shape whose diameter gradually increases toward the tip 22c. The backup ring 2 can be reduced in diameter by being provided with a cut portion 21 at one location in the circumferential direction, so that the backup ring 2 is displaced toward the inner periphery by being pushed by the protrusion 22 that falls down to the outer periphery. Therefore, when the projection 22 is tilted down until it is substantially flush with the end face 2a of the backup ring 2, the radial projection height h ′ of the projection 22 is equal to the initial gap δ _1.
The gap between the inner peripheral surface 2d of the backup ring 2 and the outer peripheral surface of the rod 4 becomes substantially zero by making the distance substantially equal to the above.

Therefore, according to this embodiment, since the backup ring 2 is made of a relatively hard thermoplastic resin such as a polyamide resin, it is difficult for the backup ring 2 to expand and deform in the radial direction even when subjected to an axial compressive load. despite those, it is possible to significantly reduce the gap [delta] ₁ and the outer circumferential surface of the rod 4 to the high pressure during. For this reason, the seal body 1
May be made of, for example, NBR (nitrile rubber) or the like.
3, protrude into the gap [delta] ₁ to the high pressure at can be prevented from causing damage called "Erosion".

Further, the results can be a thermoplastic resin of rigid backup ring 2, since the pressure resistance is improved, it is possible to increase the gap [delta] ₂ between the housing 3 and the rod 4. Moreover, for the reasons stated above, in an initial state in which the pressure in the pressure introduction space S _H does not act, there is no need to so small a gap [delta] ₁ between the backup ring 2 and the rod 4, thus the mounting groove 32 and the backup ring 2 There is no need to tighten the dimensional tolerance in the radial direction, and the thermoplastic resin such as polyamide resin is inexpensive as compared with PTFE, so that the processing cost and material cost of the backup ring 2 can be reduced.

The projection 22 is not limited to the cross-sectional shape shown in FIG. 3 as long as the projection 22 falls down to the outer peripheral side by receiving the compressive load in the axial direction. For example, FIGS. 5A to 5E show other examples of the cross-sectional shape of the protrusion 22.

Among them, FIG. 5 (A) shows that, in order to easily fall down to the outer peripheral side by receiving an axial load,
The inner peripheral surface 22b of the projection 22 is formed as an R-shaped convex surface.

FIG. 5B shows an example in which the inner peripheral surface 22b of the projection 22 is formed as an R-shaped convex surface, and the end 22c is formed as an R-shaped convex surface so that the end 22c is not easily crushed by an axial load.

FIG. 5C shows the inner peripheral surface 2 of the projection 22 when the projection 22 falls down to the outer peripheral side due to the axial load.
2b between the end face 2a of the backup ring 2
This concave surface 22d is formed in an R-shape so as not to cause cracks due to tensile stress in 2d, thereby preventing the concentration of tensile stress. This is particularly effective under conditions where generation of debris due to breakage of the projection 22 and contamination are disliked.

FIG. 5D shows a shape in which the projection 22 is inclined toward the outer peripheral side in the initial shape, that is, the tip 2 of the projection 22.
2c is formed so as to be larger in diameter than the outer peripheral surface 2c of the backup ring 2. In this case, when the backup ring 2 receives an axial load due to pressure, the projection 22 not only falls down more reliably to the outer peripheral side, but also has an allowance for the projection 22 to extend to the outer peripheral side from the beginning. You can fill a gap [delta] ₁ more reliably. Further, if the entire cross section is completely crushed by the axial load when the projection 22 falls down to the outer peripheral side, even if the gap δ ₁ between the backup ring 2 and the rod 4 can be filled, The backup ring 2 and the rod 4
Although the friction with this increases and stick-slip due to the friction easily occurs, such a problem can be prevented by forming the shape as shown in FIG. 5D.

FIG. 5E shows a groove 23 formed between the outer peripheral surface 2c of the backup ring 2 and the base outer peripheral surface 22a of the projection 22. For example, the gap δ ₁ between the backup ring 2 and the rod 4 is the radial projection height h ′ when the projection 22 falls to the outer peripheral side (see FIG. 3).
If it is smaller, the protrusion 22 that has fallen to the outer peripheral side is the outer peripheral surface 2 c of the backup ring 2 and the bottom surface 32 of the mounting groove 32.
a, the friction between the backup ring 2 and the rod 4 increases due to the reaction force, and stick-slip due to the friction tends to occur. However, if the meat escape groove 23 is formed, Since the amount of crushing when the protrusion 22 falls down to the outer peripheral side is reduced, such a problem can be prevented.

In the backup ring 2 shown in FIGS. 1, 2 and 4, the projections 22 are formed on the outer peripheral ends of both end faces 2a and 2b. This is to eliminate the need to consider the direction of the protrusion 22 when inserting the protrusion 22 into the groove 32, and it goes without saying that the protrusion 22 may be formed only on one end surface.

Further, as described above, the projections 22 by the axial load equal to or greater than a predetermined value by the pressure of the pressure introducing space S _H, that fall down to the outer peripheral side, but is displaced to the inner circumferential side of the backup ring 2, the pressure and pressure introducing space S _H, depending on the relationship between the rigidity of the projection 22 is intended to be maintained in the state shown in FIG. 4 (B).

Next, FIG. 6 is a half sectional view showing a second embodiment in which the sealing device according to the present invention is used as a rod seal, cut along a plane passing through an axis, and FIG. FIG. 4 is an enlarged partial cross-sectional view showing a part of the backup ring in FIG.

The second embodiment is different from the first embodiment in that, instead of the above-described projection 22, the outer peripheral surface 2c which is the surface facing the bottom surface 32a of the mounting groove 32 in the backup ring 2. That is, the projection 24 is formed. In a state where the backup ring 2 is not mounted in the mounting groove 32, as shown in FIG. 7, the projection 24 extends substantially in the radial direction.
It is formed larger than the diameter.

[0038] In a state of mounting the backup ring 2 in the mounting groove 32, protrusion 24 is collapsing deformed by the reaction force thereof, the backup ring 2, to reduce the gap [delta] ₁ between the backup ring 2 and the rod 4 like,
It is always urged toward the inner circumference. Therefore, even no pressure state operating pressure is not introduced, such as a hydraulic pressure introducing space S _H, it is possible to fill the gap [delta] _1.

In this case, the projection 24 is preferably formed to be relatively thin so that the projection 24 can easily fall down when the backup ring 2 is mounted in the mounting groove 32. However, the more thin, so early creep easily occurs in the temperature condition or the like, since it may impair the effect of filling the gap [delta] _1, the sealing device used in the unlikely relatively low temperature conditions Creep It is valid.

In the second embodiment,
The protrusion 24 is formed at an end of the outer peripheral surface 2c of the backup ring 2 on the atmosphere side space _SL side, but the axial position of the protrusion 24 is not particularly limited.

In the sealing device according to each of the above-described embodiments, the mounting groove 32 is provided in the housing 3 which is an outer peripheral member, and the seal body 1 mounted on the housing 3 is a rod 4 which is an inner peripheral member. The mounting groove is formed on the outer peripheral surface of an inner peripheral member (piston), such as a piston seal, and the seal body 1 is an inner peripheral member such as a cylinder. For those which come into sliding contact with the peripheral surface, the backup ring 2
May be formed in a positional relationship opposite to that shown in the figure.

In the sealing device according to each of the above-described embodiments, the protrusion 22 or 24 may have a continuous shape or an intermittent shape in the circumferential direction. In this case, processing is easier if the shape is continuous in the circumferential direction, but it is preferable that the shape be interrupted in the circumferential direction in order to facilitate falling down.

[0043]

According to the sealing device of the first aspect of the present invention, the back-up ring has an end face formed with a projection which is in contact with a corner of the mounting groove of one of the members or an end face near the corner. Because of this, the backup ring inclines with good responsiveness around the protrusion by the axial load from the seal body that receives pressure, and reduces the gap between the backup ring and the other member, so that the seal body protrudes into this gap. And "eating" due to this can be effectively prevented. Further, since the gap can be reduced when the pressure is increased without using a soft PTFE-based material for the backup ring, it is possible to improve the pressure resistance and reduce the material cost. Since it is not necessary to set a small gap, the processing cost can be reduced.

According to the sealing device of the second aspect of the present invention,
The protrusion according to claim 1 is to fall down to the corner of the mounting groove by an axial load equal to or more than a predetermined value to displace the backup ring toward the other member, so that the gap between the backup ring and the other member is reduced. As a result, it is possible to effectively prevent the seal main body from protruding into the gap and “eating” due to the protrusion. When the pressure rise is relatively small, the backup ring is inclined around the projection to fill the gap, and when the pressure rise is relatively large, the projection falls down and the backup ring is moved to the other member side as described above. Since the gap is filled by displacing the backup ring, it can be used for both low pressure and high pressure, and there is no need to change the material of the backup ring depending on the pressure condition.

According to the sealing device of the third aspect of the present invention,
The protrusion height in the axial direction of the protrusion according to claim 1 or 2 is (1).
When the backup ring is pressed by the seal body and tilted with the projection as a fulcrum, the gap between the end of the seal body side on the inner peripheral surface and the other member is substantially zero. Therefore, the protrusion of the seal body and “eating” caused by the protrusion can be reliably prevented.

According to the sealing device of the third aspect of the present invention,
The backup ring has a projection that elastically contacts the bottom surface of the mounting groove formed in one member and urges the backup ring toward the other member. Can be filled, and it is possible to effectively prevent the seal main body from protruding into the gap and “eating” caused by the protrusion. Further, since the gap can be reduced when the pressure is increased without using a soft PTFE-based material for the backup ring, it is possible to improve the pressure resistance and reduce the material cost. Since it is not necessary to set a small gap, the processing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a first embodiment in which a sealing device according to the present invention is used as a rod seal, cut along a plane passing through an axis.

FIG. 2 is a cross-sectional view of the backup ring according to the first embodiment, cut along a plane passing through an axis.

FIG. 3 is an enlarged partial sectional view showing a part of the backup ring.

FIGS. 4A and 4B are explanatory views showing the operation according to the first embodiment, omitting a seal body, wherein FIG. 4A is an initial state, and FIG.
Is a low pressure introduction state, and (C) is a high pressure introduction state.

FIG. 5 is a partial cross-sectional view showing various examples of a cross-sectional shape of a projection in the backup ring.

FIG. 6 is a half sectional view showing a second embodiment in which the sealing device according to the present invention is used as a rod seal, cut along a plane passing through an axis.

FIG. 7 is an enlarged partial sectional view showing a part of a backup ring according to the second embodiment.

FIG. 8 is a half sectional view showing a mounted state of a sealing device according to a conventional technique, cut along a plane passing through an axis.

FIG. 9 is a half sectional view showing a state in which a high pressure from a pressure introducing space acts during use in the sealing device according to the conventional technique, cut along a plane passing through an axis.

FIG. 10 is a half sectional view showing a mounted state of another sealing device according to a conventional technique, cut along a plane passing through an axis.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Seal main body 11, 12 Seal lip 2 Backup ring 21 Cutting part 23 Meat escape groove 22, 24 Projection 3 Housing (one member) 31 Inner peripheral surface 32 Mounting groove 32b Corner 4 Rod (other member) _SH pressure introduction Space _SL Atmospheric space

Claims (4)

[Claims] 1. Two members (3, 3) arranged concentrically with each other.
4) a seal body (1) mounted in an annular mounting groove (32) formed in one member (3) and slidably in contact with the other member (4); A backup ring (2) disposed on the low pressure side of the seal body (1); and a low pressure side corner (32b) of the mounting groove (32) on an end face (2a) of the backup ring (2). Or a projection (22) for contacting the end face near the corner (32b). 2. The projection (22) falls down to the corner (32b) side of the mounting groove (32) due to an axial load of a predetermined value or more and displaces the backup ring (2) toward the other member (4). The sealing device according to claim 1, wherein: Wherein the axial thickness of the backup ring (2) H, the radial width T, when the gap between the backup ring (2) and the other member (4) and [delta] _1, projections (2
The height h of 2) is h = (delta) ₁ * T / H, The sealing device of Claim 1 or 2 characterized by the above-mentioned. 4. Two members (3, 3) arranged concentrically with each other.
4) a seal body (1) mounted in an annular mounting groove (32) formed in one member (3) and slidably in contact with the other member (4); And a backup ring (2) disposed on the low pressure side of the seal body (1), wherein the backup ring (2) has a bottom surface (32a).
A projection (24) formed so as to elastically contact the backup ring (2) toward the other member (4) by being elastically contacted with the sealing member.