JP2007139179A - Piston seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston seal having no directionality in sealing action by having a seal lip on both ends of the seal, and exhibiting excellent sealing performance. <P>SOLUTION: In the piston seal 1 attached to an attachment groove 22 provided in a piston 21 and slidably brought into close contact with a cylinder 23, a cylindrical material is cut in round slices by knife-cutting so as to form a washer shaped seal member 1', and the seal member 1' is deformed to be a cylindrical shape while enlarging the diameter by a diameter enlargement tool, and is fitted into the attachment groove 22. A rake set for a knife used for knife-cutting is used and a warp having an arc shaped cross section is formed on the seal member 1', and the seal member 1' is deformed to the cylindrical shape so that a concave surface 5 of the warp faces an outer peripheral side, and seal lips 7 and 8 adhered to an inner peripheral surface of the cylinder 23 are formed on the seal member 1' attached to the attachment groove 22 on axial both ends. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piston seal that is attached to a piston and seals between the two by being in close contact with a cylinder. The piston seal of the present invention is used, for example, for a shock absorber piston in a vehicle such as an automobile, or for other pressure devices.

  Conventionally, as shown in FIG. 5, a piston seal 1 is known which is mounted in an annular mounting groove 22 provided on the outer peripheral surface of a piston 21 and slidably comes into contact with the inner peripheral surface of a cylinder 23. The piston seal 1 includes a step of forming a washer-like seal member 1 ′ (see FIG. 6) by cutting a cylindrical material (not shown) made of a predetermined material into a ring with a knife cut, and as shown in FIG. The cylindrical seal member 1 ′ is manufactured and assembled by performing a step of deforming it into a cylindrical shape while expanding the diameter with a taper-shaped diameter expansion jig 31 and fitting it into the mounting groove 22 of the piston 21.

  Further, the piston seal 1 is assembled by using the diameter expansion jig 31 to tilt the washer-like seal member 1 ′ to the axial direction around the entire circumference with the inner diameter end as a fulcrum, and then to the inner diameter end. The diameter of the seal member 1 'is increased to a cylindrical shape, and the cylindrical seal member 1' is then fed into the mounting groove 22 of the piston 21 and fitted (see Patent Document 1).

Therefore, in the piston seal 1 that has been assembled, as shown by an arrow in FIG. 5, one axial end portion 2 formed by the inner diameter end portion of the washer-like seal member 1 ′ is contracted (reduced diameter). with the direction of the restoring force P ₁ is applied, acting restoring force P ₂ of the extension (diameter) direction in the other axial end portion 3 which is formed by the radially outer end portion of the washer-like sealing member 1 ' One end 2 in the former axial direction is in close contact with the bottom surface of the mounting groove 22, and the other end 3 in the other axial direction is in close contact with the inner peripheral surface of the cylinder 23.

  However, this conventional technique has the following problems.

(1) Since acts restoring force P ₂ of the direction of extension in the axial direction other end 3 formed by the radially outer end portion of the washer-like sealing member 1 'as mentioned above, the end portion of the other axial 3 forms a seal portion 4 in close contact with the inner peripheral surface of the cylinder 23, but the axially one end portion 2 formed by the inner diameter end portion of the washer-like seal member 1 ′ has a restoring force P _{1 in the} contraction direction. Therefore, the one end portion 2 in the axial direction does not contact the inner peripheral surface of the cylinder 23, and therefore a seal portion for the cylinder 23 is not formed. Therefore, directionality is set in the sealing action of the piston seal 1, and in order to seal both sides in the axial direction, the two piston seals 1 must be arranged back to back as shown in FIG.

(2) Also, at the other end 3 in the axial direction where the seal portion 4 can be formed, the seal action of the seal portion 4 depends only on the restoring force of the seal member 1 ′, and a particularly sharp seal lip is formed. I don't mean. Therefore, the sealing action may become unstable and the quality may vary, and there is a possibility that the sealing function cannot be exhibited particularly at low pressures.

  As another conventional technique for the present invention, a method for manufacturing a piston is described in Patent Document 2 below. In this manufacturing method, a piston main body and a tubular sealing member attached to the piston main body are subjected to heat treatment. , Whereby a procedure is provided for causing at least one of the ends of the tubular sealing member to move radially outward. However, this conventional technique deforms the sealing member by applying “heat treatment” as described in the above sentence, and the present invention is different in configuration from using “warping”.

JP 2001-173780 A JP-T-2002-531797 (Claim 6, 0014, FIG. 5)

  In view of the above, an object of the present invention is to provide a piston seal that has seal lips at both ends of a seal and thus has no directionality in sealing action and can exhibit excellent sealing performance.

  In order to achieve the above object, a piston seal according to claim 1 of the present invention is a piston seal that is mounted in an annular mounting groove provided on the outer peripheral surface of the piston and is slidably in close contact with the inner peripheral surface of the cylinder. The piston seal is characterized in that seal lips that are in close contact with the inner peripheral surface of the cylinder are formed at both ends in the axial direction of the piston seal.

  The piston seal according to claim 2 of the present invention is a piston seal that is mounted in an annular mounting groove provided on the outer peripheral surface of the piston and is slidably in close contact with the inner peripheral surface of the cylinder. A washer-like seal member is formed by cutting a ring with a knife cut, and the seal member is deformed into a cylindrical shape while expanding its diameter with a diameter expansion jig, and is set as a knife used for the knife cut in the piston seal fitted into the mounting groove. Using the rake angle, the washer-like seal member is formed with a circular arc-shaped warp, and the seal member is deformed into a cylindrical shape so that the concave surface of the warp faces the outer peripheral side, and is mounted in the mounting groove The seal member is characterized in that seal lips are formed at both ends in the axial direction so as to be in close contact with the inner peripheral surface of the cylinder.

  The piston seal according to claim 3 of the present invention is the piston seal according to claim 1 or 2, wherein the bottom surface of the mounting groove is tapered so that the outer diameters of the seal lips at both ends in the axial direction are the same or approximate. The inclined surface is provided.

  A process of forming a washer-like seal member by cutting a cylindrical material made of a predetermined material such as resin with a knife cut, and using the rake angle set for the knife used for the knife cut, Mold warpage. As a result, the seal member is formed in a circular arc shape in cross section. Warpage is not elastic deformation but plastic deformation. Next, the step of deforming the seal member formed with the warp into a cylindrical shape while expanding the diameter with a diameter expansion jig and fitting it into the mounting groove of the piston is performed. At this time, the concave surface of the warp (the concave surface of the arc) The seal member is deformed into a cylindrical shape so as to face the outer peripheral side, and the seal member is fitted into the mounting groove in this posture. Since the concave surface of the warp faces the outer peripheral side, the pointed ends formed at both ends thereof also face the outer peripheral side, so that a seal lip is formed which is in close contact with the inner peripheral surface of the cylinder.

  If there is a dimensional difference in the outer diameter of the seal lip formed at both ends in the axial direction in this way, there is a concern that a difference in performance occurs between the two seal lips. Therefore, when dealing with this, a tapered inclined surface is provided on the bottom surface of the mounting groove so that the outer diameters of the seal lips at both ends in the axial direction are the same or approximate.

  As described above, since the restoring force in the contraction direction acts on one end in the axial direction formed by the inner diameter end of the washer-like seal member, the seal lip formed on the one end in the axial direction has an outer diameter. The size tends to be small. In addition, since one end portion in the axial direction is enlarged in the process of deformation into a cylindrical shape at the time of assembly, the wall thickness is reduced, which also tends to reduce the outer diameter of the seal lip. On the other hand, since the restoring force in the expansion direction acts on the other end portion in the axial direction formed by the outer diameter end portion of the washer-like seal member, the seal lip formed on the other end portion in the axial direction has an outer diameter dimension. Tends to be large. Therefore, since there is such a tendency, the groove depth of the mounting groove is set shallowly at a portion where one end in the axial direction is mounted and deeply set at a portion where the other end in the axial direction is mounted. Preferably, as for the direction of inclination of the tapered inclined surface provided on the bottom surface of the mounting groove, the groove depth extends from the portion where one end in the axial direction is mounted to the portion where the other end in the axial direction is mounted. It is preferable to make the shape gradually deeper.

  The present invention has the following effects.

  That is, in the piston seal according to the first or second aspect of the present invention, the seal lip is formed at both ends of the seal so as to be in close contact with the cylinder. Become. Therefore, it is not necessary to arrange two seal members back to back as in the prior art described above, and only one seal member is required. Therefore, a piston seal that is easy to manufacture, assemble, handle, and requires a small installation space. Can be provided. Further, if the direction of the sealing action is not set, the mounting direction of the seal is not limited, so that the assembly can be simplified from this point.

  Further, when the warp is set in the seal, the seal lip is strongly brought into close contact with the inner peripheral surface of the cylinder using the repulsive force of the warp. Therefore, it is possible to provide a piston seal that exhibits stable sealing performance from a low pressure region.

  Further, since the sealing lip is not formed by heat treatment as in the prior art, the present invention can be applied to a material that is weak against heat.

  Furthermore, in the piston seal according to claim 3 of the present invention, since the outer diameters of the seal lips formed at both ends in the axial direction of the seal are the same or close to each other, there is a difference in performance (sealability, Differences in performance regarding sliding load, wear characteristics, etc. are unlikely to occur. Therefore, also from this point, the directionality of the seal can be eliminated, and the application range of the seal can be expanded.

  The present invention includes the following embodiments.

Constitution···
(1) A feature is given to the shape of the washer-like seal member, and the assembly direction of the washer-like seal member is defined.
(2) The washer-like seal member is not a flat shape but a shape that is intentionally warped, and the amount of warpage is set by a knife angle (rake angle) at the time of cutting from the material.
(3) The piston groove is fitted in a direction in which the concave surface of the warp faces radially outward.
(4) The inner diameter side of the washer is fitted into the groove with a restoring force in the contraction direction, and the outer diameter side does not have a restoring force in the contraction direction, and a clearance is set from the piston groove bottom.
(5) Both ends of the seal member after the groove fitting have lips (R shape).
effect···
(6) By making the both ends of the seal member lip (R shape), it is possible to seal both sides with one component, and to positively contact the inner peripheral surface of the cylinder by the repulsive force of the warp. A stable sealing property can be obtained.
(7) Since the lip is formed by warping and not the lip by heat treatment, the lip can be easily formed without requiring a heating means.

  The method for manufacturing and assembling the piston seal of the present invention is as follows.

(A) A method for manufacturing and assembling a piston seal 1 that is mounted in an annular mounting groove 22 provided on the outer peripheral surface of the piston 21 and that is slidably brought into close contact with the inner peripheral surface of the cylinder 23. Forming a washer-like seal member 1 ′ by cutting with a knife cut, and a step of deforming the seal member 1 ′ into a cylindrical shape and expanding the seal member 1 ′ with a diameter-enlarging jig 31 and fitting the seal member 1 ′ into the mounting groove 22. In a method for manufacturing and assembling a piston seal, a procedure for forming a warp having a circular arc shape in the washer-like seal member 1 ′ using a rake angle θ set in the knife 32 used for the knife cut, and a concave surface of the warp The seal member 1 ′ is deformed into a cylindrical shape so that the seal member 1 ′ is directed to the outer peripheral side, and the seal member 1 ′ in the state of being mounted in the mounting groove 22 A method for manufacturing and assembling a piston seal, wherein seal lips 7 and 8 are formed in close contact with the inner peripheral surface of a cylinder 23.
(B) In the method for manufacturing and assembling the piston seal described in (a) above, the bottom surface of the mounting groove 22 is tapered so that the outer diameters of the seal lips 7 and 8 at both ends in the axial direction are the same or approximate. A method of manufacturing and assembling a piston seal, characterized in that a surface is provided.

  Next, embodiments of the present invention will be described with reference to the drawings.

  The piston seal according to the embodiment is used for a shock absorber for automobiles and motorcycles. In this case, the material of the piston is generally iron or iron-based sintered metal, and the material of the piston seal is generally polytetrafluoroethylene resin (PTFE).

  As shown in FIG. 3, the piston seal according to this embodiment is a piston seal 1 that is mounted in an annular mounting groove 22 provided on the outer peripheral surface of the piston 21 and slidably contacts the inner peripheral surface of the cylinder 23. Thus, seal lips 7 and 8 that are in close contact with the inner peripheral surface of the cylinder 23 are formed at both ends in the axial direction.

  The piston seal according to this embodiment is a piston seal 1 that is mounted in an annular mounting groove 22 provided on the outer peripheral surface of the piston 21 and is slidably in close contact with the inner peripheral surface of the cylinder 23. The material S is cut with a knife to form a washer-like seal member 1 ′, and the seal member 1 ′ is deformed into a cylindrical shape while being expanded in diameter by the diameter-enlarging jig 31 and fitted into the mounting groove 22. In FIG. 3, the seal member 1 ′ is formed into a circular arc shape by using a rake angle θ set in the knife 32 used for the knife cut, and the seal member 1 ′ is cylindrical so that the warped concave surface 5 faces the outer peripheral side. The seal member 1 ′ that is deformed and mounted in the mounting groove 22, that is, the piston seal 1, has seal lips 7 and 8 that are in close contact with the inner peripheral surface of the cylinder 23 at both axial ends. It is obtained by form.

  The manufacturing and assembly procedures are as follows.

  That is, first, as shown in FIG. 1, the washer-shaped seal member 1 'is formed by cutting the cylindrical material S made of the above-described resin material by a knife cut. At this time, a rake angle θ is set for the knife 32 used for knife cutting, and the warp is intentionally formed on the seal member 1 ′ by using the rake angle θ. The magnitude of the rake angle θ is determined by the inclination angle of the tip inclined surface 33 of the knife 32. The seal member 1 ′ is formed into a flat shape (flat plate shape) unless warping is formed, but is formed into a three-dimensional shape having a circular arc shape by forming the warp.

  Next, as shown in FIG. 2, the seal member 1 ′ with the warp formed is deformed into a cylindrical shape while being expanded using a taper-shaped diameter expansion jig 31, and is fitted into the mounting groove 22 of the piston 21. At this time, the seal member 1 ′ is deformed into a cylindrical shape so that the warped concave surface 5 faces the outer peripheral side and the convex surface 6 faces the inner peripheral side, and the seal member 1 ′ is fitted in the mounting groove 22 of the piston 21 in this posture. . The seal member 1 ′ fitted in the mounting groove 22 is the piston seal 1.

  As shown in FIG. 3, in the piston seal 1 fitted in the mounting groove 22, the warped concave surface 5 faces the outer peripheral side (left side in the figure), so that the pointed portions formed at both ends are also on the outer peripheral side. Thus, seal lips 7 and 8 that are in close contact with the inner peripheral surface of the cylinder 23 are formed on both end portions of the piston seal 1 respectively.

Also in this embodiment, when the piston seal 1 is assembled, the washer-like seal member 1 ′ is used as a fulcrum with the washer-like seal member 1 ′ as a fulcrum on one side in the axial direction. It is the same as that in the prior art that the inner diameter end is expanded, and then the inner diameter end portion is expanded into a cylindrical shape, and then the cylindrical sealing member 1 ′ is fed into the mounting groove 22 of the piston 21 and fitted. In the piston seal 1 that has completed the above, a restoring force P1 in the contraction (reduction) direction acts on _one end 2 in the axial direction formed by the inner diameter end of the washer-like seal member 1 ′, and the washer-like seal member 1 in the other axial end portion 3 is formed by the radially outer end portion of the 'the same applies to the restoring force P ₂ of the extension (diameter) direction acts. In this embodiment, in addition to these, the seal member 1 ′ is warped and the seal lips 7 and 8 projecting outward in the radial direction are formed, and the closeness to the cylinder 23 is increased accordingly. As a result, the sealing performance can be improved. The warping causes the seal lips 7 and 8 to be brought into close contact with the inner peripheral surface of the cylinder 23 by utilizing the repulsive force.

Further, since the restoring force P1 in the contraction direction acts on _one end 2 in the axial direction formed by the inner diameter end of the washer-like seal member 1 ′ as described above, the one end 2 in the axial direction acts on the one end 2 in the axial direction. The seal lip 7 to be molded tends to have a small outer diameter φA. In addition, since one end portion 2 in the axial direction is enlarged in the process of being deformed into a cylindrical shape at the time of assembly, the thickness of the seal lip 7 is easily reduced. On the other hand, since the acts restoring force P ₂ of the direction of extension in the axial direction other end 3 formed by the radially outer end portion of the washer-like sealing member 1 'is formed into the end portion 3 of the other axial The seal lip 8 tends to have a large outer diameter φB. Therefore, due to these reasons, as shown in FIG. 4A, the seal lips 7 and 8 formed at both ends in the axial direction are likely to have a dimensional difference C (C = φB−φA) in the outer diameter. When the dimensional difference C occurs in this way, there is a concern that a performance difference may occur in the sealing action.

  Therefore, in this embodiment, as shown in FIG. 4 (a), a tapered (conical surface) inclined surface 24 is provided on the bottom surface of the mounting groove 22, so that the outside of the seal lips 7, 8 at both ends in the axial direction is provided. The diameters φA and φB are set to the same size (φA = φB). The inclination direction of the inclined surface 24 is such that the groove depth gradually increases from the part where the one end 2 in the axial direction is attached to the part where the other end 3 is attached in the axial direction. The groove depth difference D is matched with the outer diameter dimension difference C (C = D). For example, when the dimensional difference C of the outer diameter is found to be 0.346 mm as a result of the detailed examination, the groove depth difference D is set to 0.346 mm accordingly. This makes it difficult for a difference in performance to occur between the seal lips 7 and 8 at both ends in the axial direction, and the directionality of the seal can be eliminated from this point.

  Further, the piston seal according to the present invention is sometimes referred to as a piston bearing because of its function of being attached to the piston 21 and slidably in close contact with the cylinder 23.

Process explanatory drawing which shows the procedure of the manufacturing / assembling method of the piston seal which concerns on the Example of this invention. Process explanatory drawing which shows the procedure of the manufacturing / assembling method of the piston seal which similarly concerns on the Example of this invention. Sectional drawing of the principal part of the piston seal which concerns on the Example of this invention Sectional drawing of the principal part of the piston seal which concerns on the other Example of this invention. Cross-sectional view of the main part of a piston seal according to a conventional example Process explanatory drawing which shows the procedure of the manufacturing and assembly method concerning a prior art example Cross-sectional view of the main part of a piston seal according to another conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston seal 1 'Seal member 2 One axial end part 3 The other axial end part 4 Seal part 5 Warp concave surface 6 Warp convex surface 7, 8 Seal lip 21 Piston 22 Mounting groove 23 Cylinder 24 Tapered inclined surface 31 Diameter expansion jig 32 Female 33 Tip inclined surface S Cylindrical material

Claims (3)

A piston seal (1) mounted in an annular mounting groove (22) provided on the outer peripheral surface of the piston (21) and slidably in close contact with the inner peripheral surface of the cylinder (23),
A piston seal characterized in that seal lips (7) and (8) that are in close contact with the inner peripheral surface of the cylinder (23) are formed at both axial ends of the piston seal (1). A piston seal (1) mounted in an annular mounting groove (22) provided on the outer peripheral surface of the piston (21) and slidably in close contact with the inner peripheral surface of the cylinder (23), comprising a cylindrical material (S ) With a knife cut to form a washer-like seal member (1 ′), and the seal member (1 ′) is deformed into a cylindrical shape while being expanded with a diameter-enlarging jig (31), thereby the mounting groove (22). In the piston seal (1) fitted to
The washer-like seal member (1 ′) is formed with a circular arc-shaped warp by using a rake angle (θ) set in the knife (32) used for the knife cut, and the concave surface (5) of the warp has an outer peripheral side. The seal member (1 ′) is deformed into a cylindrical shape so as to face, and the cylinder (23) is disposed at both ends in the axial direction of the seal member (1 ′) mounted in the mounting groove (22). A piston seal characterized in that a seal lip (7) (8) is formed in close contact with the inner peripheral surface of the piston seal. The piston seal according to claim 1 or 2,
A piston seal characterized in that a tapered inclined surface (24) is provided on the bottom surface of the mounting groove (22) so that the outer diameter dimensions of the seal lips (7) and (8) at both axial ends are the same or approximate.

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