JP2011021723A - Sealing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing structure capable of more securely preventing a packing from being extruded with a smaller number of parts and by using a high-hardness hard material as a material of a backup ring. <P>SOLUTION: In the sealing structure, a surface on the side to be slid to a taper surface 71a in an annular groove 71 in the backup ring 10 is formed as a taper surface, a taper angle on the taper surface in the backup ring 10 is set larger than a taper angle on the taper surface 71a in the annular groove 71, and an annular edge E on the high pressure side of the taper surface in the backup ring 10 is configured to be freely slid to the taper surface 71a in the annular groove 71. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sealing structure.

  2. Description of the Related Art Conventionally, a sealing structure is known that includes a sealing device that is disposed in an annular groove provided in one of two members and seals an annular gap between the two members. Such a conventional sealing structure will be described with reference to FIGS.

  9 and 10 are schematic cross-sectional views of the sealing structure according to Conventional Example 1. FIG. 9 shows a state where the pressure difference between the high pressure side (H) and the low pressure side (L) is small (or not), and FIG. 10 shows a state where the pressure difference is large. In this sealing structure, the annular gap between the shaft 60 and the housing 70 is sealed by disposing the packing 100 in the annular groove 75 provided on the inner peripheral surface of the shaft hole of the housing 70. A backup ring 200 is disposed adjacent to the packing 100 on the low pressure side (L) of the packing 100 in the annular groove 75. The backup ring 200 is provided to prevent the inner peripheral edge 101 of the packing 100 from protruding into a minute gap between the shaft 60 and the housing 70.

  The backup ring 200 is configured such that a gap S is provided with respect to the shaft 60 in a state where an external force is not applied from the viewpoint of mounting properties and dimensional tolerances. When the pressure difference between the high pressure side (H) and the low pressure side (L) becomes large, the backup ring 200 is compressed between the packing 100 and the side wall surface of the annular groove 75, and is expanded and deformed in the radial direction. Thereby, the clearance gap between the backup ring 200 and the axis | shaft 60 is lose | eliminated, and the protrusion of the inner peripheral edge of the packing 100 is suppressed.

  Here, when a rubber material (NBR or the like) having a relatively low hardness is used as the material of the packing 100, a resin material (PTFE or the like) is also used as the material of the backup ring 200. In this case, the backup ring 200 is sufficiently stretched and deformed in the radial direction by axial compression, so that the gap between the backup ring 200 and the shaft 60 can be eliminated more reliably.

  However, in use conditions where the pressure difference between the high pressure side (H) and the low pressure side (L) is very large, a hard material (PA, PEEK, POM, PPS, etc.) are used. In this case, it is difficult to eliminate the gap between the backup ring 200 and the shaft 60 because the amount of radial deformation is small with respect to the compression in the axial direction. Therefore, the inner peripheral edge of the packing 100 may protrude and be damaged. Alternatively, by setting the gap S small, the mounting workability is lowered.

  As a countermeasure against this, a technique using a backup ring 210 made of a hard material and a backup ring 220 made of a relatively soft resin material as in Conventional Example 2 shown in FIG. 11 is also known. However, in this case, since a plurality of backup rings are required, not only a large arrangement space has to be secured, but also the cost increases due to an increase in the number of parts.

Also, the clearance between the shaft and the backup ring does not always occur by sliding the backup ring with respect to the shaft, instead of eliminating the clearance between the shaft and the backup ring using the elastic deformation of the backup ring. Techniques for doing so are also known. FIG. 12 is a schematic cross-sectional view of a sealing structure according to Conventional Example 3. In this conventional example, on the low pressure side of the groove bottom surface of the annular groove 71 provided on the inner peripheral surface of the housing 70, a tapered surface 71a that decreases in diameter from the high pressure side (H) toward the low pressure side (L). Is provided. Further, the outer peripheral surface of the backup ring 300 disposed on the low pressure side (L) adjacent to the packing 150 is also configured by a tapered surface whose diameter decreases from the high pressure side (H) toward the low pressure side (L). The taper angle of the tapered surface 71a on the annular groove 71 side and the taper angle of the outer peripheral surface of the backup ring 300 are configured to be equal.

  With such a configuration, as long as there is a pressure difference between the high pressure side (H) and the low pressure side (L), the backup ring 300 is kept pressed to the low pressure side (L). The state where there is no gap between is maintained. Further, according to the conventional example 3, even when the distance between the shaft 60 and the housing 70 (shaft hole) fluctuates due to the eccentricity of the shaft 60, the backup ring 300 is pushed into the low pressure side (L). Thus, it is possible to suppress the occurrence of a gap between the backup ring 300 and the shaft 60.

  However, in the case of the sealing structure according to Conventional Example 3, the outer peripheral surface and the inner peripheral surface of the backup ring 300 are configured to come into surface contact with the tapered surface 71a and the outer peripheral surface of the shaft 60, respectively. Therefore, depending on the surface condition and dimensional accuracy of each component, the backup ring 300 may not move smoothly in the axial direction, and a gap may be generated between the backup ring 300 and the shaft 60. In particular, when the backup ring 300 is made of a hard material (PA, PEEK, POM, PPS, etc.), the backup ring 300 itself is not deformed so much that a gap is more likely to occur. For example, when the shaft 60 is eccentric, the distance between the shaft 60 and the housing 70 is the narrowest at a certain position in the circumferential direction, and is the largest at a position of 180 degrees from the position. Therefore, if the backup ring 300 itself is not deformed so much, a gap is likely to occur in the vicinity where the distance between the shaft 60 and the housing 70 is the widest.

  As a countermeasure against this, a technique using a backup ring 310 made of a hard material and a backup ring 320 made of a relatively soft resin material as in Conventional Example 4 shown in FIG. 13 is also known. However, in this case, since a plurality of backup rings are required as in the above-described conventional example 2, not only a large arrangement space has to be secured, but also the cost increases due to an increase in the number of parts.

JP 11-315925 A JP 09-2222058 A1 JP-A-11-072162

  An object of the present invention is to provide a sealing structure that can suppress the protrusion of packing more reliably even when a hard material having a high hardness is used as a material for a backup ring with a small number of parts.

  The present invention employs the following means in order to solve the above problems.

That is, the sealing structure of the present invention is
A sealing structure provided with a sealing device disposed in an annular groove provided in one of the two members and sealing an annular gap between the two members,
On the low pressure side of the groove bottom surface of the annular groove, a tapered surface is provided in which the distance from the other member gradually decreases from the high pressure side toward the low pressure side,
The sealing device includes:
A rubber-like elastic packing disposed on the high-pressure side;
A backup ring made of a hard material, disposed on the low pressure side adjacent to the packing, and slidable with respect to the tapered surface;
In a sealing structure comprising:
The surface of the backup ring that slides on the tapered surface of the annular groove is a tapered surface, and the taper angle of the tapered surface of the backup ring is greater than the taper angle of the tapered surface of the annular groove. The annular end portion on the high pressure side of the tapered surface of the backup ring is configured to be slidable with respect to the tapered surface of the annular groove.

  According to the present invention, the annular edge portion on the high-pressure side of the taper surface in the backup ring is configured to be slidable with respect to the taper surface in the annular groove. Slide in the state. Therefore, the back-up ring moves more smoothly in the axial direction than the taper angle of each taper surface is set equal and the taper surfaces are in surface contact with each other. In addition, since the hard material having high hardness is used as the material of the backup ring, even if the backup ring itself is not easily deformed, the backup ring itself (when the tapered surfaces are in surface contact) with respect to the eccentricity of the two members. (Relatively), it is easy to tilt, and the generation of gaps can be suppressed.

  The surface of the backup ring that slides with respect to the other member is also configured as a tapered surface, and the annular end portion on the high-pressure side of the tapered surface is slidable with respect to the other member. It should be configured.

  As a result, the backup ring can be moved more smoothly in the axial direction, and the backup ring itself can be more easily inclined with respect to the eccentricity of the two members, so that the generation of a gap can be more reliably suppressed.

  It is preferable that a gap be secured between the backup ring and the low pressure side surface of the annular groove regardless of the position of the backup ring.

  As a result, it is possible to prevent the backup ring from striking against the low-pressure side surface of the annular groove, hindering the movement of the backup ring, and applying an unreasonable force to the backup ring.

  In addition, said each structure can be employ | adopted combining as possible.

  As described above, according to the present invention, even if a hard material having a high hardness is used as the material of the backup ring with a small number of parts, the protrusion of the packing can be more reliably suppressed.

FIG. 1 is a schematic cross-sectional view of a sealing structure according to Embodiment 1 of the present invention. FIG. 2 is a diagram for explaining the dimensional relationship of main members constituting the sealing structure according to the first embodiment of the present invention. FIG. 3 is an operation explanatory view of the sealing structure according to the first embodiment of the present invention. FIG. 4 is an operation explanatory view of the sealing structure according to the first embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of a sealing structure according to Embodiment 2 of the present invention. FIG. 6 is an operation explanatory view of the sealing structure according to the second embodiment of the present invention. FIG. 7 is an operation explanatory view of the sealing structure according to the second embodiment of the present invention. FIG. 8 is a schematic cross-sectional view of a sealing structure according to Embodiment 3 of the present invention. FIG. 9 is a schematic cross-sectional view of a sealing structure according to Conventional Example 1. FIG. 10 is a schematic cross-sectional view of a sealing structure according to Conventional Example 1. FIG. 11 is a schematic cross-sectional view of a sealing structure according to Conventional Example 2. FIG. 12 is a schematic cross-sectional view of a sealing structure according to Conventional Example 3. FIG. 13 is a schematic cross-sectional view of a sealing structure according to Conventional Example 4.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

  The sealing structure according to the present embodiment is a structure in which an annular gap between two members is sealed by a sealing device. The two members are provided concentrically, and these two members may move relatively (at least one of rotation and reciprocation) or may be stationary with respect to each other. Moreover, although these two members are provided concentrically, it is not always necessary to maintain the concentric state, and an eccentric state may occur. According to the sealing device according to the present embodiment, the sealed state can be suitably maintained even when the two members are in an eccentric state. In the sealing structure according to the present embodiment, one of the axial directions is the high pressure side (H) and the other is the low pressure side (L). However, there may be a state in which a differential pressure is not generated between the pressures on both sides. Further, a fluid to be sealed (such as oil) may be sealed on the high pressure side (H), and the air on the low pressure side (L) may be air, or the fluid to be sealed may be sealed on both sides. . In addition, as a suitable example which can apply the sealing structure which concerns on a present Example, the injector part in a direct-injection engine, the cylinder for construction machines, the cylinder for general machines, and a shock absorber can be mentioned.

Example 1
With reference to FIGS. 1-4, the sealing structure which concerns on Example 1 of this invention is demonstrated.

<Entire sealing structure>
The sealing structure according to the present embodiment is a structure in which an annular gap between the shaft 60 (the other member of the two members) and the housing 70 (one member of the two members) is sealed by a sealing device. . The sealing device according to this embodiment includes a packing 50 and a backup ring 10. The packing 50 is an O-ring made of a rubber-like elastic body (for example, NBR), and is arranged on the high-pressure side (H). The inner peripheral surface of the packing 50 is slidably in close contact with the outer peripheral surface of the shaft 60, and the inner peripheral surface is a shaft hole inner peripheral surface of the housing 70 (more specifically, a groove of an annular groove 71 described later). Closely slidably contacts the bottom surface. The backup ring 10 is made of a hard material (for example, PA, PEEK, POM, PPS), and is disposed on the low pressure side (L) adjacent to the packing 50.

The sealing device including the packing 50 and the backup ring 10 is disposed in an annular groove 71 provided on the inner peripheral surface of the shaft hole of the housing 70. On the low pressure side (L) at the groove bottom surface of the annular groove 71, a tapered surface 71a is provided that decreases in diameter from the high pressure side (H) toward the low pressure side (L). That is, the distance between the tapered surface 71a and the shaft 60 gradually decreases from the high pressure side (H) toward the low pressure side (L). The backup ring 10 is configured to be slidable with respect to the tapered surface 71 a of the annular groove 71. And the outer peripheral surface 11 of the backup ring 10 is also comprised by the taper surface which diameter-reduces toward the low voltage | pressure side (L) from a high voltage | pressure side (H).

<Details of annular groove and backup ring>
The taper angle of the outer peripheral surface 11 in the backup ring 10 is set to be larger than the taper angle of the taper surface 71 a provided in the annular groove 71. That is, as shown in FIG. 2, in a cross section passing through the axis (the axis 60, the shaft hole of the housing 70, the packing 50, and the axis of the backup ring 10), the angle formed between the generatrix and the axis on the outer peripheral surface 11 of the backup ring 10 When α is set and θ is an angle formed between the generatrix and the axis on the taper surface 71a of the annular groove 71, α> θ is satisfied. Needless to say, the taper angle of the outer peripheral surface 11 of the backup ring 10 is 2α, and the taper angle of the taper surface 71a provided in the annular groove 71 is 2θ.

  Further, when the shaft 60, the shaft hole of the housing 70, and the backup ring 10 are arranged concentrically, the radial thickness on the high pressure side (H) of the backup ring 10 is T, and the high pressure side of the tapered surface 71a. The distance between the edge of (H) (the same is true of the groove bottom surface of the annular groove 71 where the tapered surface 71a is not provided) and the surface of the shaft 60 is t1, and the edge on the low pressure side (L) of the tapered surface 71a. When the distance between the shaft 60 and the surface of the shaft 60 is t2, t2 <T ≦ t1 is satisfied.

  Furthermore, even when the backup ring 10 moves to the lowest pressure side (L) in the usage environment (except when there is an abnormality), there is a gap U between the backup ring 10 and the side surface of the annular groove 71 on the low pressure side. Is ensured (see FIG. 4). With the above configuration, the annular edge portion E on the high pressure side (H) of the outer peripheral surface 11 of the backup ring 10 can maintain a (substantially) line contact state with the tapered surface 71a of the annular groove 71. Yes.

<Description of operation>
According to the sealing structure according to the present embodiment configured as described above, the backup ring 10 depends on the pressure difference between the high pressure side (H) and the low pressure side (L) and the eccentricity of the shaft 60 with respect to the shaft hole of the housing 70. Moves to the high pressure side (H) or the low pressure side (L). At this time, the annular edge portion E slides with respect to the tapered surface 71 a in the annular groove 71. Hereinafter, this point will be described in detail.

  As the pressure difference between the high pressure side (H) and the low pressure side (L) increases, the packing 50 is pressed toward the low pressure side (L). Thereby, the backup ring 10 is pushed to the low pressure side (L) by the packing 50 and moves to the low pressure side (L). At this time, the inner peripheral surface of the backup ring 10 slides in surface contact with the outer peripheral surface of the shaft 60, and the outer peripheral surface side of the backup ring 10 has an annular edge portion E with respect to the tapered surface 71a (substantially). ) Slide with line contact. The more the backup ring 10 moves to the low pressure side (L), the smaller the distance between the shaft 60 and the tapered surface 71a at the portion where the backup ring 10 is in contact. Therefore, the more the backup ring 10 moves to the low pressure side (L), the greater the amount of compression from the shaft 60 and the tapered surface 71a. Therefore, it can suppress that a clearance gap produces between the backup ring 10 and the axis | shaft 60, and can suppress that a part of packing 50 protrudes into the clearance gap between these backup rings 10 and the axis | shaft 60. FIG.

  Further, when the shaft 60 is eccentric with respect to the shaft hole of the housing 70, the distance between the shaft 60 and the housing 70 (the shaft hole) changes. FIG. 3 shows a case where the distance is small (distance S1), and FIG. 4 shows a case where the distance is large (distance S2).

As the distance between the shaft 60 and the housing 70 (the shaft hole thereof) becomes smaller, the backup ring 10 moves to the high pressure side (H) (see FIG. 3). As the distance increases, the backup ring 10 moves to the low pressure side (L) (see FIG. 4). However, when the shaft 60 is decentered, the distance between the shaft 60 and the housing 70 is the narrowest at a certain position in the circumferential direction and the widest at a position of 180 degrees from the position. Accordingly, when viewed in a cross section passing through the axis, the backup ring 10 apparently moves in the axial direction as shown in FIGS. 3 and 4, but the entire backup ring 10 moves in the axial direction parallel to the axis. Not a translation. In practice, when the shaft 60 is eccentric, the backup ring 10 is deformed so as to be inclined with respect to the axis of the shaft 60. When the backup ring 10 is viewed in a cross section passing through the axis, the axis is apparently Translate to.

<Excellent points of this embodiment>
As described above, according to the sealing structure according to the present embodiment, the annular edge portion E on the high pressure side (H) of the outer peripheral surface (tapered surface) 11 of the backup ring 10 is relative to the tapered surface 71 a of the annular groove 71. It is configured to be slidable. Therefore, the sliding portion slides in a (substantially) line contact state. Therefore, the backup ring 10 moves more smoothly in the axial direction as compared with the configuration in which the taper angles of these tapered surfaces are set equal and the tapered surfaces are in surface contact with each other. In addition, since the hard material having high hardness is used as the material of the backup ring 10, even if the backup ring 10 itself is not easily deformed, the backup ring 10 itself (the tapered surfaces are in surface contact with each other) against the eccentricity of the shaft 60. (As compared to the case of (1)), it is easy to tilt, and the generation of gaps can be suppressed. Thereby, the protrusion of the packing 50 can be suppressed and damage to the packing 50 can be suppressed.

  Thus, in the sealing structure according to the present embodiment, the protrusion of the packing 50 can be effectively suppressed even with only one backup ring 10. Therefore, it is not necessary to secure a large arrangement space compared to the case where two types of backup rings made of different materials are used, and an increase in cost can be suppressed.

  In the present embodiment, when the backup ring 10 is pushed by the packing 50, the backup ring 10 itself is not deformed and has a high hardness so as to move more reliably (including a tilting operation when eccentric). It is preferable to use a material (a Rockwell hardness of 65 HR or higher is desirable). This is because if a material with low hardness is used, especially when the shaft 60 is decentered, the backup ring 10 itself is deformed, resulting in “sagging” over time. For this reason, a gap may be generated between the backup ring 10 and the shaft 60.

  Further, in the sealing structure according to the present embodiment, even when the backup ring 10 moves to the lowest pressure side (L) in the usage environment (excluding abnormal cases), the low pressure side of the backup ring 10 and the annular groove 71. It is comprised so that the clearance gap U may be ensured between these side surfaces. Therefore, it is possible to prevent the backup ring 10 from abutting against the low-pressure side surface of the annular groove 71 and hindering the movement of the backup ring 10 and applying an excessive force to the backup ring 10. Further, since the movement of the backup ring 10 is not hindered, it is possible to suppress the occurrence of a gap between the backup ring 10 and the shaft 60 or the housing 70.

(Example 2)
5 to 7 show a second embodiment of the present invention. In this embodiment, the inner peripheral surface of the backup ring is also configured as a tapered surface, and the sliding portion between the backup ring and the shaft is configured to slide in a (substantially) line contact state. Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  In the backup ring 20 according to the present embodiment, the outer peripheral surface 21 is configured by a tapered surface that is reduced in diameter from the high pressure side (H) toward the low pressure side (L), as in the case of the first embodiment. Accordingly, as in the case of the first embodiment, the annular edge portion E1 on the high-pressure side (H) of the outer peripheral surface 21 of the backup ring 20 is in (substantially) line contact with the tapered surface 71a of the annular groove 71. It is possible to maintain the state.

  And in the case of a present Example, the internal peripheral surface 22 of the backup ring 20 is comprised by the taper surface which diameter-expands toward the low voltage | pressure side (L) from the high voltage | pressure side (H). Thereby, the annular end edge portion E <b> 2 on the high-pressure side (H) of the inner peripheral surface 22 of the backup ring 20 can maintain a (substantially) line contact state with the shaft 60. In the cross section passing through the axis, if the angle between the generatrix and the axis on the inner peripheral surface 22 of the backup ring 20 is β, the corresponding angle on the shaft 60 is 0 °, and β> 0 ° is satisfied. Yes. Needless to say, the taper angle of the inner peripheral surface 22 of the backup ring 20 is 2β.

  In the case of the present embodiment as well, even when the backup ring 20 moves to the lowest pressure side (L) in the usage environment (except for abnormal cases), the backup ring 20 and the side surface on the low pressure side of the annular groove 71 A gap U is ensured between them (see FIG. 7).

  With the above-described configuration, according to the sealing structure according to the present embodiment, the backup ring 20 has the high pressure side (H) or the low pressure side (L) according to the pressure difference between the high pressure side (H) and the low pressure side (L). ) At this time, on the outer peripheral surface side of the backup ring 20, the annular edge portion E1 slides in a state of (substantially) line contact with the tapered surface 71a, and on the inner peripheral surface side, the annular edge portion E2 is relative to the shaft 60. Sliding in a (substantially) line contact.

  Further, when the shaft 60 is eccentric with respect to the shaft hole of the housing 70, the distance between the shaft 60 and the housing 70 (the shaft hole) changes. FIG. 6 shows a case where the distance is small, and FIG. 7 shows a case where the distance is large. As the distance between the shaft 60 and the housing 70 (the shaft hole) becomes smaller, the backup ring 20 moves to the high pressure side (H) (see FIG. 6). As the distance increases, the backup ring 10 moves to the low pressure side (L) (see FIG. 7). When viewed in a cross section passing through the axis, the backup ring 20 apparently moves in the axial direction as shown in FIGS. 6 and 7, but the entire backup ring 20 moves in the axial direction parallel to the axis. The reason for this is as described in the first embodiment.

As described above, in the case of the sealing structure according to the present embodiment, the backup ring 20 is in a state where the annular edge portions E1 and E2 on the high-pressure side (H) on both the outer peripheral surface side and the inner peripheral surface side are in line contact (substantially) Is configured to slide. Therefore, as compared with the case of the first embodiment, the backup ring 20 can move more smoothly in the axial direction, and the backup ring 20 itself is more easily inclined with respect to the eccentricity of the shaft 60. Therefore, generation | occurrence | production of a clearance gap can be suppressed more reliably. Even when the shaft 60 is inclined with respect to the backup ring 20, the annular edge portion E <b> 2 on the inner peripheral surface side of the backup ring 20 is in a (substantially) line contact state, and the shaft extends over the entire circumference. The state in contact with 60 can be maintained. Therefore, in the case of the backup ring 20 according to the present embodiment, the generation of a gap can be suitably suppressed even with respect to the inclination of the shaft 60. Thus, the backup ring 20 according to the present embodiment is suitable when the shaft 60 can be inclined. In addition, when the configuration in which the inner peripheral surface of the backup ring is in surface contact with the shaft and the outer peripheral surface of the backup ring is in surface contact with the tapered surface of the annular groove provided in the housing, the shaft is inclined. In this case, a gap is generated between the backup ring and the shaft. This is because in this case, the backup ring itself hardly tilts, and the shaft is tilted with respect to the backup ring. And about the contact position with respect to the axis | shaft in the inner periphery of a backup ring, the part which contacts in the edge of a high voltage | pressure side (H) and the part which contacts in the edge of a low voltage | pressure side (L) will arise. For this reason, a gap is generated between the end of the high pressure side (H) on the inner periphery of the backup ring and the shaft. Further, as in the case of the first embodiment and the third embodiment described below, the inner peripheral surface of the backup ring is brought into surface contact with the shaft, and the outer peripheral surface of the backup ring is an annular groove provided in the housing. In the case of making line contact with the tapered surface, it is possible to suppress the occurrence of a gap between the backup ring and the shaft even with respect to the inclination of the shaft. This is because the backup ring can be tilted to some extent with respect to the housing, so that when the shaft is tilted, the backup ring is tilted together with the shaft to prevent a gap from being generated between the backup ring and the shaft. be able to. In other words, even if the shaft is tilted, the backup ring does not tilt with respect to the shaft, so that the state in which the inner peripheral surface of the backup ring is in surface contact with the shaft can be maintained.

(Example 3)
FIG. 8 shows a third embodiment of the present invention. In the present embodiment, a case will be described in which the outer peripheral surface of the shaft is also composed of a tapered surface. Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  In the sealing structure according to the present embodiment, the outer peripheral surface of the shaft 61 is constituted by a tapered surface whose diameter increases from the high pressure side (H) toward the low pressure side (L). Needless to say, in the cross section passing through the axis, if the angle between the generatrix and the axis on the outer peripheral surface of the shaft 61 is γ, the taper angle of the tapered surface is 2γ.

  In addition, the backup ring 30 according to the present embodiment has an outer peripheral surface 31 constituted by a tapered surface that decreases in diameter from the high pressure side (H) toward the low pressure side (L) as in the case of the first embodiment. Yes. Accordingly, as in the case of the first embodiment, the annular edge portion E on the high pressure side (H) of the outer peripheral surface 31 of the backup ring 30 is in line contact with the tapered surface 71a of the annular groove 71 (substantially). It is possible to maintain the state. In addition, the inner peripheral surface of the backup ring 30 according to the present embodiment is configured by a tapered surface whose diameter increases from the high pressure side (H) toward the low pressure side (L), and the taper angle is the outer peripheral surface of the shaft 61. The taper angle is set to be the same. Therefore, the inner peripheral surface of the backup ring 30 slides in surface contact with the outer peripheral surface of the shaft 61.

  Needless to say, according to the sealing structure according to the present embodiment configured as described above, the same effects as those of the first embodiment can be obtained. However, the sealing structure according to the present embodiment is not suitable for an application in which the shaft 61 and the housing 70 are relatively reciprocated, and is suitable for an application in which these are relatively rotated or are stationary with respect to each other.

<Others>
By setting the taper angle of the inner peripheral surface of the backup ring 30 in the third embodiment to be larger than the taper angle 2γ of the outer peripheral surface of the shaft 61, the inner periphery is the same as in the case of the second embodiment. The annular edge portion on the high pressure side (H) of the surface may be maintained in a (substantially) line contact state with respect to the shaft 61. In this way, the backup ring 30 can move more smoothly in the axial direction, and the backup ring 30 itself is more easily inclined with respect to the eccentricity of the shaft 61.

Moreover, in each said Example, the structure which arrange | positions a sealing device in the annular groove 71 provided in the internal peripheral surface of the shaft hole of the housing 70 was shown. However, a configuration may be adopted in which an annular groove is provided on the shaft side and a sealing device is disposed in the annular groove. In this case, a tapered surface that increases in diameter from the high pressure side toward the low pressure side is provided on the low pressure side of the groove bottom surface of the annular groove provided on the shaft side. That is, the distance between the tapered surface and the housing gradually decreases from the high pressure side to the low pressure side. And the internal peripheral surface of a backup ring is comprised by the taper surface set to the taper angle larger than the taper angle of the taper surface in an annular groove. Thereby, the high-pressure-side annular edge portion of the inner peripheral surface (tapered surface) of the backup ring can maintain a (substantially) line contact state with the tapered surface of the annular groove. Needless to say, the outer peripheral surface side may also be configured as a tapered surface so as to contact the inner peripheral surface of the shaft hole of the housing in a (substantially) line contact state. In addition, even when the backup ring moves to the lowest pressure side in the usage environment (excluding abnormal cases), a gap is secured between the backup ring and the side surface on the low pressure side of the annular groove. It goes without saying that it is preferable to do this.

  In addition, the backup ring in each of the above-described embodiments may be of a type in which no cut part (separation part) is provided in the circumferential direction, or one place in the circumferential direction in order to improve wearability. It may be of a type in which a cut portion is provided.

DESCRIPTION OF SYMBOLS 10 Backup ring 11 Outer peripheral surface 20 Backup ring 21 Outer peripheral surface 22 Inner peripheral surface 30 Backup ring 31 Outer peripheral surface 50 Packing 60, 61 Shaft 70 Housing 71 Annular groove 71a Tapered surface E, E1, E2 Annular edge part U Clearance

Claims (3)

A sealing structure provided with a sealing device disposed in an annular groove provided in one of the two members and sealing an annular gap between the two members,
On the low pressure side of the groove bottom surface of the annular groove, a tapered surface is provided in which the distance from the other member gradually decreases from the high pressure side toward the low pressure side,
The sealing device includes:
A rubber-like elastic packing disposed on the high-pressure side;
A backup ring made of a hard material, disposed on the low pressure side adjacent to the packing, and slidable with respect to the tapered surface;
In a sealing structure comprising:
The surface of the backup ring that slides on the tapered surface of the annular groove is a tapered surface, and the taper angle of the tapered surface of the backup ring is greater than the taper angle of the tapered surface of the annular groove. A sealing structure characterized in that the annular end portion on the high pressure side of the tapered surface of the backup ring is configured to be slidable with respect to the tapered surface of the annular groove.   The surface of the backup ring that slides with respect to the other member is also configured as a tapered surface, and the annular end portion on the high-pressure side of the tapered surface is slidable with respect to the other member. The sealing structure according to claim 1, wherein the sealing structure is configured.   3. The gap according to claim 1, wherein a gap is secured between the backup ring and the low-pressure side surface of the annular groove regardless of the position of the backup ring. Sealing structure.

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