JP5344163B2 - Sealing device - Google Patents

Description

  The present invention relates to a sealing device that seals between two members that are arranged concentrically and move relative to each other, and in particular, a seal body is mounted together with a backup ring in a mounting groove of one member, and the seal body is provided by the backup ring. Is related to what is supported.

  2. Description of the Related Art Conventionally, as a sealing device used for a device that generates a high pressure in a fluid to be sealed, such as a hydraulic cylinder, a shock absorber, a plunger pump, or the like, a device as shown in FIG. 6 is known.

  That is, the sealing device 100 shown in FIG. 6 includes an outer peripheral member 110 (for example, a cylinder of a hydraulic device) and an outer peripheral surface of an inner peripheral member 120 (for example, a piston of a hydraulic device) that is arranged to reciprocate in the axial direction on the inner periphery. Between the sealing body S1 and the sealing body 101 formed of rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity), and the anti-sealing space of the sealing body 101. The back-up ring 102 is disposed on the side of S2 (the space opposite to the sealed space S1 when viewed from the seal body 101), and is mounted in a mounting state in a mounting groove 121 formed on the outer peripheral surface of the inner peripheral member 120. The seal body 101 is a so-called O-ring having a circular cross section, and is interposed between the bottom surface 121a of the mounting groove 121 and the inner peripheral surface of the outer peripheral member 110 in a properly compressed state.

  Here, the backup ring 102 is formed of a synthetic resin material harder than the seal body 101, and when the sealed space S <b> 1 becomes a high pressure, the seal body 101 that receives this pressure is the anti-sealed space in the mounting groove 121. In order to prevent damage to the gap G1 between the groove shoulder on the S2 side and the inner peripheral surface of the outer peripheral member 110, the seal body 101 is supported in the mounting groove 121 from the anti-sealing space S2 side. Is.

  However, according to the sealing device 100 having the above-described configuration, the gap G2 between the backup ring 102 and the outer peripheral member 110 is increased depending on the dimensional tolerances of the mounting groove 121 and the backup ring 102, and the outer peripheral member 110 is inherently formed. Although the backup ring 102 is provided to fill the gap G1 between the backup ring 102 and the inner peripheral member 120, the seal body 101 protrudes into the gap G2 between the backup ring 102 and the outer peripheral member 110 as shown in FIG. May be damaged.

  Therefore, as a technique for preventing such a gap G2 between the backup ring 102 and the outer peripheral member 110, for example, a technique disclosed in the following prior art document is known.

JP-A-3-113179

  However, what is disclosed in Patent Document 1 is that the backup ring is in surface contact with the bottom surface of the mounting groove and the friction is large, so that it is difficult to move quickly to the low pressure side when the sealed space becomes high pressure. It is pointed out that there is a possibility that misassembly will occur when the ring is shaped to be front and back when it is assembled into the mounting groove. Further, since the outer diameter of the backup ring has a substantially right-angled edge, the possibility that the seal body is damaged by being pressed against this edge has not been solved.

  The present invention has been made in view of the above points, and a technical problem thereof is a sealing device having a structure in which a seal body is supported by a backup ring in a mounting groove. The object of the present invention is to provide a structure that can reliably prevent breakage due to protrusion and that has good operability against pressure changes without causing erroneous assembly.

As a means for effectively solving the technical problem described above, the sealing device according to the invention of claim 1 is provided in an annular mounting groove formed in one member of two members arranged concentrically with each other. A seal body that is mounted and slidably in contact with the other member; and a backup ring that is disposed in the mounting groove on the side opposite to the seal body of the seal body and is made of a material that is more rigid than the seal body, The bottom surface of the mounting groove has a shape that gradually becomes shallower toward the anti-sealing space at the mounting position of the backup ring, and the opposite end of the backup ring with respect to the bottom surface of the mounting groove is the bottom surface of the mounting groove. A convex surface that is in line contact is formed , and this convex surface is an R surface or a mountain shape that is symmetrical with respect to the thickness direction . In addition, the anti-sealing space here is a space on the opposite side to the sealing space when viewed from the seal body.

According to the sealing device of the first aspect of the invention, when the axial load due to the pressure on the sealed space side acts on the backup ring via the seal body, the backup ring faces the inside of the mounting groove toward the anti-sealed space side. While displacing, the convex end slides on the bottom surface of the mounting groove and rides toward the shallowest portion, so that the gap between the opposing surfaces of the backup ring and the other member is reduced, and It is deformed in the radial direction so as to be in close contact, and prevents the seal body from protruding to the low pressure side. Since the convex end of the backup ring slides in line contact with the bottom surface of the mounting groove, the frictional resistance is suppressed, so the responsiveness to pressure fluctuation on the sealed space side is good, and therefore the sealed space side It is possible to reliably prevent the seal body from protruding to the low pressure side when the pressure increases. In addition, since the backup ring has a symmetrical cross-sectional shape with respect to its thickness direction, it has an excellent effect of preventing erroneous assembly.

1 is a half sectional view showing a first embodiment of a sealing device according to the present invention by cutting along a plane passing through an axis O. FIG. FIG. 3 is a half cross-sectional view showing a state in which pressure is applied to the sealing device of the first embodiment, cut along a plane passing through an axis O; FIG. 5 is a half sectional view showing a second embodiment of the sealing device according to the present invention by cutting along a plane passing through an axis O; FIG. 5 is a half sectional view showing a third embodiment of the sealing device according to the present invention by cutting along a plane passing through an axis O; FIG. 6 is a half cross-sectional view showing a fourth embodiment of the sealing device according to the present invention by cutting along a plane passing through an axis O; FIG. 10 is a half cross-sectional view showing an example of a sealing device according to the prior art cut by a plane passing through an axis O. In the prior art, it is the half sectional view which cuts and shows the state which produced the seal | sticker main body by the plane which passes along the axial center O. FIG.

  Hereinafter, a preferred embodiment of a sealing device according to the present invention will be described with reference to the drawings. First, in the first embodiment shown in FIG. 1, reference numeral 2 is an outer peripheral member (for example, a cylinder of a hydraulic device), and reference numeral 3 is concentrically arranged on the inner periphery of the outer peripheral member 2 and is freely reciprocated in the axial direction. It is the made inner peripheral member (for example, piston of a hydraulic device). The inner peripheral member 3 corresponds to one member described in claim 1, and the outer peripheral member 2 corresponds to the other member described in claim 1.

  The sealing device 1 seals the working oil in the sealed space S1 between the outer peripheral member 2 and the inner peripheral member 3, and is formed of a rubber-like elastic material (rubber material or a synthetic resin material having rubber-like elasticity). The O-ring 11 and a backup ring 12 disposed on the side of the O-ring 11 opposite to the sealed space S2 (the space opposite to the sealed space S1 when viewed from the O-ring 11) are provided on the outer circumferential surface of the inner circumferential member 3. The mounting groove 31 is annularly formed with the axis O as the center, and is mounted in a housed state.

  The bottom surface of the mounting groove 31 formed on the outer peripheral surface of the inner peripheral member 3 is formed in a cylindrical surface at a portion close to the sealed space S1, that is, a portion corresponding to the mounting position of the O-ring 11 (hereinafter referred to as a cylindrical surface bottom surface). 31a), the portion near the opposite end, that is, the portion corresponding to the mounting position of the backup ring 12, is formed in a conical surface shape in which the groove depth gradually decreases toward the anti-sealing space S2. (Hereinafter referred to as a conical bottom 31b).

  The O-ring 11 is a packing having a circular cross-sectional shape (the cross-sectional shape shown in the drawing) cut along a plane passing through the axis O and corresponds to the seal body according to claim 1, and the cylindrical bottom surface of the mounting groove 31. 31a and the inner peripheral surface 2a of the outer peripheral member 2 are interposed in an appropriately compressed state, and are slidably brought into close contact with the inner peripheral surface 2a of the outer peripheral member 2, whereby the sealed space S1 and the anti-sealed space S2 Are separated from each other.

  The backup ring 12 is formed in a flat annular shape by a synthetic resin material, such as PTFE (polytetrafluoroethylene) or nylon, which is harder than the O-ring 11, and is formed in the O-ring 11 and the mounting groove 31. It is interposed between the inner surface on the side of the anti-sealing space S2. In addition, an appropriate axial gap exists between the backup ring 12 and the rising surface 31c on the anti-sealing space S2 side in the mounting groove 31 in a no-load state.

  An inner diameter portion which is an opposite end portion of the backup ring 12 with respect to the conical bottom surface 31b of the mounting groove 31 forms an R-shaped convex surface 12a which is symmetrical with respect to the thickness direction (axial direction). As shown by a point C in FIG. 1, it is in close contact with the conical bottom 31b in a line contact state. Further, the end of the backup ring 12 facing the side opposite to the conical surface bottom surface 31b, that is, the outer peripheral surface 12b has a cylindrical shape and is in close proximity to and opposed to the inner peripheral surface 2a of the outer peripheral member 2. .

  The sealing device 1 having the above-described configuration is subjected to an O-ring when an operating pressure is applied to the hydraulic oil in the sealed space S1 in the mounted state shown in FIG. 1 (the sealed space S1 becomes high pressure). 11 is displaced in the mounting groove 31 toward the anti-sealing space S2 having a relatively low pressure, and therefore, an axial load due to pressure from the sealing space S1 acts on the backup ring 12 via the O-ring 11. .

  For this reason, the backup ring 12 displaces the inside of the mounting groove 31 toward the anti-sealing space S2 side, and the R-shaped convex surface 12a of the inner diameter slides with the conical surface bottom surface 31b of the mounting groove 31 to form the shallowest portion. 2, the clearance between the opposing surfaces of the cylindrical outer peripheral surface 12b of the backup ring 12 and the inner peripheral surface 2a of the outer peripheral member 2 is reduced, and the sealed space S1 is further increased in pressure, so that FIG. As shown in FIG. 2, the outer peripheral surface 12b is in close contact with the inner peripheral surface 2a of the outer peripheral member 2 in the process of displacement to the contact position with the rising surface 31c on the anti-sealing space S2 side in the mounting groove 31.

  Moreover, since the R-shaped convex surface 12a of the inner diameter of the backup ring 12 is in a line contact state with the conical surface bottom surface 31b of the mounting groove 31, the frictional resistance is particularly low, and particularly those made of PTFE have extremely low friction, and therefore the sealed space S1. Therefore, the O-ring 11 can be reliably prevented from protruding to the low pressure side when the pressure on the sealed space S1 side rises.

  Here, in the high-pressure state shown in FIG. 2, it is conceivable that a part 11 a of the O-ring 11 bites between the inner diameter portion of the backup ring 12 of the mounting groove 31 and the conical bottom surface 31 b. Since the inner diameter portion of the inner surface forms an R-shaped convex surface 12a, it is difficult for the O-ring 11 to be damaged by biting.

  Further, since the backup ring 12 has a symmetrical cross-sectional shape in the axial direction and has no front and back surfaces, no erroneous assembly is caused.

  Next, a second embodiment shown in FIG. 3 will be described. In this embodiment, the difference from the above-described first embodiment (FIG. 1) is that the backup ring 12 has an outer diameter portion facing away from the conical surface bottom surface 31b of the mounting groove 31 and an inner diameter portion. And R-shaped convex surface 12c symmetrical in the radial direction. Other configurations are the same as those in FIG.

  Therefore, according to this configuration, the backup ring 12 receives an axial load due to pressure from the sealed space S1 side through the O-ring 11 and is displaced in the mounting groove 31 toward the anti-sealed space S2 side. The R-shaped convex surface 12a of the inner diameter slides on the conical surface-shaped bottom surface 31b of the mounting groove 31 and rides up toward the shallowest portion, so that the R-shaped convex surface 12c of the outer diameter becomes the inner peripheral surface 2a of the outer peripheral member 2. , The R-shaped convex surface 12c is also in line contact, so that a low friction state can be maintained.

  Next, a third embodiment shown in FIG. 4 will be described. In this embodiment, the difference from the first embodiment (FIG. 1) described above will be described. The bottom surface of the mounting groove 31 formed on the outer peripheral surface of the inner peripheral member 3 is a portion closer to the sealed space S1, That is, the portion corresponding to the mounting position of the O-ring 11 is a cylindrical surface bottom surface 31a, and the portion near the end on the opposite side, that is, the portion corresponding to the mounting position of the backup ring 12 is on the anti-sealing space S2 side. It is formed in an R shape in which the groove depth gradually decreases in a nonlinear manner (hereinafter referred to as an R-shaped bottom surface 31d).

  On the other hand, in the backup ring 12, the inner diameter portion facing the R-shaped bottom surface 31d of the mounting groove 31 forms a chevron convex surface 12d that is symmetrical with respect to the thickness direction (axial direction). As shown by a point C in FIG. 4, the portion (inner diameter edge) is in close contact with the R-shaped bottom surface 31d in a line contact state. Other configurations are the same as those in FIG.

  Therefore, the third embodiment can also achieve the same effect as the first embodiment described above.

  Also in this case, the backup ring 12 has a cross-sectional shape symmetrical in the radial direction, that is, the outer diameter portion facing the opposite side of the R-shaped bottom surface 31d of the mounting groove 31 also forms a chevron convex surface symmetrical in the radial direction with the inner diameter portion. Can be.

  Next, a fourth embodiment shown in FIG. 5 will be described. In this embodiment, the difference from the third embodiment described above (FIG. 4) is that the cross-sectional shape of the backup ring 12 cut along the plane passing through the axis O is the base of the outer diameter and the hypotenuse on both sides in the axial direction. An equilateral triangle, more specifically, an isosceles triangle in which the oblique sides on both sides in the axial direction are longer than the base, that is, an isosceles triangle with an apex angle of an inner diameter that is in line contact with the R-shaped bottom surface 31d of the mounting groove 31, is less than 60 degrees. The inner diameter portion of the groove 31 opposed to the R-shaped bottom surface 31d forms a chevron convex surface 12d that is symmetrical with respect to the thickness direction (axial direction). Other configurations are the same as those in FIG.

  Therefore, the fourth embodiment can also achieve the same effect as the third embodiment described above. Moreover, the inner side surface 12e of the backup ring 12 facing the O-ring 11 exhibits a conical surface that recedes toward the anti-sealing space S2 toward the inner diameter side, and an angle formed with respect to the R-shaped bottom surface 31d of the mounting groove 31. Since α is larger than 60 degrees, even if the O-ring 11 is pressed against the backup ring 12 due to the pressure from the sealed space S1 side, a part of the O-ring 11 remains on the inner surface 12e of the backup ring 12 and the R of the mounting groove 31. It is not sandwiched between the bottom surface 31d. For this reason, the durability of the O-ring 11 can be further improved.

  In each of the above-described embodiments, the case where the O-ring 11 is used as the seal body is shown. However, the present invention can be applied to, for example, an X-ring (cross-section cut along a plane passing through the axis O is substantially X-shaped). The same applies to the case of using other packings such as packing.

  Furthermore, in each of the above-described embodiments, the case where the mounting groove 31 is formed in the inner peripheral member 3 has been described. However, the present invention forms the mounting groove on the inner peripheral surface 2a of the outer peripheral member 2, and the seal main body and The same applies to the case where a backup ring is attached.

  The sealing device of the present invention can be applied not only to hydraulic equipment but also as sealing means for various equipment that generates high pressure in fluid.

1 Sealing device 11 O-ring (seal body)
12 Backup rings 12a, 12c R-shaped convex surface 12d Mountain-shaped convex surface 2 Outer peripheral member (the other member)
3 Inner peripheral member (one member)
31 Mounting groove 31a Cylindrical bottom surface 31b Conical surface bottom surface 31d R-shaped bottom surface S1 Sealing space S2 Anti-sealing space

Claims (1)

A seal body that is mounted in an annular mounting groove formed in one of two members arranged concentrically with each other and slidably in contact with the other member, and the seal body in the mounting groove A back-up ring made of a material having rigidity higher than that of the seal body, and a bottom surface of the mounting groove gradually becomes shallower toward the anti-sealing space side at the mounting position of the back-up ring. At the same time, the opposite end of the backup ring with respect to the bottom surface of the mounting groove forms a convex surface that is in line contact with the bottom surface of the mounting groove, and the convex surface is an R surface or a mountain shape that is symmetrical with respect to the thickness direction. A sealing device characterized by that.

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