JP2018071623A - Dust seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent water from intruding from an outer peripheral side and rust from occurring due to water intrusion, in a dust seal 1 whose seal lip 12 faces upward.SOLUTION: A dust seal includes: a base part 11 comprising a unit of a rubber elastic body, and having a butting surface 11a capable of butting with an upper end surface 25 of an outer peripheral member 2 in a close contact manner; a seal lip 12 extending upward from the base part 11, and closely contacting with an outer peripheral surface of an inner peripheral member 3 in a slidable manner, the inner peripheral member inserted into an inner periphery of the outer peripheral member 2 in a relatively movable manner; a covering part 13 extending downward from an outer diameter side of the butting surface 11a in the base part 11; and a stationary part 14 provided in the covering part 13, and capable of being fixed to an outer periphery of the outer peripheral member 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dust seal attached so that a seal lip faces upward, and used for a front fork of a motorcycle, for example.

  In a motorcycle, a dust seal that is interposed between a bottom case of a front fork that suspends a front wheel and a fork pipe and prevents entry of dust or the like from the outside into an internal bearing is, for example, as shown in FIG. Are known.

  The front fork includes a bottom case 200 and a fork pipe 300 that is inserted into the bottom case 200 so as to be able to appear and retract. The front fork includes a spring and a damping force generation mechanism (not shown), and is input from a front wheel during traveling. The bottom case 200 absorbs vibration and impact by reciprocating in the axial direction (vertical direction) with respect to the fork pipe 300. Between the opening of the bottom case 200 and the outer peripheral surface of the fork pipe 300, an oil seal (not shown) that prevents leakage of internal hydraulic oil, and an external dust or dust disposed outside the oil seal are disposed. A dust seal 100 is provided to prevent water and the like from entering.

  As shown in FIG. 4, the dust seal 100 has a structure in which a seal body 102 having a fixed seal portion 102 a and a seal lip 102 b is integrally formed with a rubber elastic body on a reinforcing metal ring 101. In the mounted state shown in FIG. 2, the fixed seal portion 102a located on the outer periphery of the cylindrical portion 101a of the metal ring 101 is tightly fitted in an appropriately compressed state in the radial direction on the inner peripheral surface of the opening of the bottom case 200 of the front fork. In addition, the tip of the seal lip 102b on the inner peripheral side of the metal ring 101 is slidably brought into close contact with the outer peripheral surface of the fork pipe 300 (see, for example, the following prior art document).

JP 2003-307247 A

  This type of dust seal 100 has a structure in which a metal ring 101 is embedded in a seal main body 102 made of a rubber elastic body. It is inevitable that a plurality of molding marks 102c and 102d are formed by pressing protrusions for positioning and fixing in the mold, and a part of the metal ring 101 is exposed from these molding marks 102c and 102d. become.

  As shown in FIG. 3, when the dust seal 100 is attached to the upper end portion of the bottom case 200 and the seal lip 102b faces upward, the dust seal 100 is positioned outside the fixed seal portion 102a. In the molding mark 102c, in the process in which water due to rain flows down to the outer peripheral surface side of the bottom case 200 along the outer peripheral surface of the seal lip 102b, a part of this water is separated from the outer diameter portion 102e of the seal body 102 and the bottom. There is a possibility of intrusion through a gap at the abutting portion with the case 200. In this case, rust may be generated on the surface of the metal ring 101 exposed at the molding mark 102c. For this reason, a measure is taken to reduce the exposed area by passing a thin film made of a rubber elastic body around the exposed portion of the metal ring 101, but it has been difficult to completely prevent the occurrence of rust.

  The present invention has been made in view of the above points, and its technical problem is that in the dust seal with the seal lip facing upward, the intrusion of water from the outer peripheral side and the generation of rust due to this. Is to prevent.

  In order to solve the technical problem described above, the dust seal according to the invention of claim 1 is made of a single rubber elastic body, and has a base portion having an abutting surface that can be brought into close contact with the upper end surface of the outer peripheral member, and the base portion. A seal lip extending upward and slidably in contact with the outer peripheral surface of the inner peripheral member inserted in the inner periphery of the outer peripheral member so as to be capable of relative movement; and downward from the outer diameter side of the abutting surface in the base portion An enveloping part extending in a cylindrical shape and a fixing part that is provided on the enveloping part and can be fixed to the outer periphery of the outer peripheral member.

  The dust seal according to a second aspect of the present invention is characterized in that, in the configuration according to the first aspect, the fixed portion is formed of an engaging convex portion that can be engaged with a downward surface formed on the outer peripheral surface of the outer peripheral member. To do.

  A dust seal according to a third aspect of the invention is characterized in that, in the configuration of the first or second aspect, a continuous air discharge groove is formed from the inner peripheral surface of the fixed portion to the abutting surface of the base portion. is there.

  Since the dust seal according to the present invention is made of a single rubber elastic body, it does not generate rust. In addition, the abutting surface of the base portion is intimately abutted with the upper end surface of the outer peripheral member, and the enveloping portion that extends in a cylindrical shape downward from the outer diameter side covers the upper portion of the outer peripheral member from the outer peripheral side. Alternatively, it is possible to reliably prevent falling water or dust from entering the inner peripheral side of the base.

It is sectional drawing of the mounting state which cut | disconnects and shows preferable embodiment of the dust seal which concerns on this invention by the plane which passes along an axial center. It is sectional drawing which cuts and shows preferable embodiment of the dust seal which concerns on this invention by the plane which passes along an axial center. It is a half sectional view of the wearing state which cuts and shows an example of the dust seal concerning the prior art by the plane which passes along an axis. It is a semi-sectional view showing an example of a dust seal according to the prior art by cutting along a plane passing through an axis.

  Hereinafter, preferred embodiments of a dust seal according to the present invention will be described with reference to the drawings.

  In FIG. 1, reference numeral 2 is a cylindrical bottom case in a front fork of a motorcycle, and reference numeral 3 is a fork pipe in the front fork, which is inserted into the inner periphery of the bottom case 2 so as to be able to appear and retract. This front fork incorporates a spring and a damping force generation mechanism (not shown), and the bottom case 2 reciprocates in the axial direction (vertical direction) with respect to the fork pipe 3 with respect to vibrations and impacts input from the front wheels during traveling. It absorbs by moving. The bottom case 2 corresponds to the outer peripheral member described in claim 1, and the fork pipe 3 corresponds to the inner peripheral member described in claim 1.

  A stepped surface 21 facing downward is formed in the vicinity of the upper end of the outer peripheral surface of the bottom case 2, that is, the outer peripheral surface of the bottom case 2 is relatively large in diameter above the stepped surface 21 (hereinafter referred to as the large-diameter side). (Referred to as the outer peripheral surface 22) and a relatively small diameter (hereinafter referred to as a small-diameter side outer peripheral surface 23) below the step surface 21. Further, a chamfer 24 having a small diameter upward is formed at the upper end portion of the large-diameter outer peripheral surface 22. The step surface 21 corresponds to a downward surface formed in the second aspect.

  Between the upper end opening of the bottom case 2 and the outer peripheral surface of the fork pipe 3, there is an oil seal (not shown) for preventing leakage of internal hydraulic oil and the dust seal 1 of the present invention located outside the oil seal. Is provided.

  As shown in FIG. 2, the dust seal 1 is formed of a single rubber elastic body, and includes a base portion 11, a seal lip 12 extending upward from the base portion 11, and an abutting surface 11 a of the base portion 11. An enveloping portion 13 that extends downward in a cylindrical shape from the outer diameter side and an engaging convex portion 14 as a fixing portion formed at the lower end portion of the enveloping portion 13 are provided.

  The base 11 has an inner diameter larger than the outer diameter of the fork pipe 3 and smaller than the outer diameter surface 22 and the chamfer 24 on the large diameter side of the bottom case 2, and has a radial thickness of the seal lip 12 and the encapsulating portion 13. The lower surface of the engaging projection 14 is an abutting surface 11a that is in close contact with the upper end surface 25 of the bottom case 2 in the mounted state shown in FIG. .

  The seal lip 12 has a substantially conical cylindrical shape whose outer peripheral surface gradually decreases in diameter upward, and the tip inner diameter portion 12a is slightly smaller than the outer peripheral surface of the fork pipe 3 in the unmounted state shown in FIG. In other words, in the mounted state shown in FIG. 1, it is slidably brought into close contact with the outer peripheral surface of the fork pipe 3 with an appropriate margin.

  The encapsulated portion 13 has an axial length L in the unmounted state shown in FIG. 1 is the same as or slightly shorter than the axial length from the step surface 21 to the upper end surface 25 of the bottom case 2, and the inner diameter is substantially the same as the outer diameter surface 22 on the large diameter side of the bottom case 2, as shown in FIG. In the mounted state, the large-diameter side outer peripheral surface 22 of the bottom case 2 is covered closely from the outer peripheral side.

  The engagement convex portion 14 has an inner peripheral surface 14 a having a smaller diameter than the outer peripheral surface 22 on the large diameter side of the bottom case 2, in other words, a smaller diameter than the inner peripheral surface of the enveloping portion 13, preferably the outer periphery on the small diameter side of the bottom case 2. The surface 23 is substantially the same diameter as that of the inner peripheral surface of the encapsulating portion 13, and is a hooking surface 14 b that faces upward and forms a plane that is substantially perpendicular to the axis, and the inner peripheral surface 14 a A chamfer 14c having a large diameter downward is formed in the lower part.

  Reference numeral 15 is an air discharge groove. The air discharge groove 15 extends from the lower end of the chamfer 14 c of the engaging convex portion 14 through the inner peripheral surface 14 a of the engaging convex portion 14, the hooking surface 14 b, and the inner peripheral surface of the enveloping portion 13. The abutting surface 11a reaches the outer diameter portion and is formed at one or more locations in the circumferential direction. The air discharge groove 15 does not reach the inner diameter end of the abutting surface 11a, and therefore the abutting surface 11a is continuous in the circumferential direction.

  Further, the surface pressure of the abutting surface 11a against the upper end surface 25 of the bottom case 2 is increased and the fluid is dammed at a position on the inner diameter side of the air discharge groove 15 on the abutting surface 11a of the base 11. An annular groove 16 having a function is formed.

  1, the dust seal 1 has an abutting surface 11a which is a lower surface of the base portion 11 closely in contact with an upper end surface 25 of the bottom case 2 and an engaging convex portion 14 as a retaining surface. 14 b, the tip end inner diameter portion 12 a of the seal lip 12 positioned on the upper side of the bottom case 2 is fixed to the bottom case 2 by being hooked on the downward stepped surface 21 of the bottom case 2. By being in close contact with the outer peripheral surface so as to be slidable, dust or water from the outside is prevented from entering the bottom case 2.

  The dust seal 1 is mounted so as to cover the bottom case 2, that is, the encapsulating portion 13 and the engaging convex portion 14 exist so as to cover the upper outer periphery of the bottom case 2, and the seal lip 12 is provided on the bottom case 2. Since the outer peripheral surface is formed so as to gradually become smaller in diameter between the upper end opening and the outer peripheral surface of the fork pipe 3, when water droplets or the like fall from above the dust seal 1, Flows down from the outer peripheral surface of the seal lip 12 via the outer peripheral surface of the encapsulating portion 13 and drops from the lower end portion of the engaging convex portion 14, and therefore, water or the like enters the inner periphery of the dust seal 1. Can be prevented.

  In the process in which the bottom case 2 is displaced downward with respect to the fork pipe 3, an upward frictional force is generated in the seal lip 12. This frictional force causes the bottom case 2 to move upward with respect to the fork pipe 3. The downward frictional force generated in the seal lip 12 in the process of displacement is small, and the slipping of the dust seal 1 from the bottom case 2 due to the upward frictional force is applied to the engaging convex portion 14. The stop surface 14 b is prevented by being hooked on the downward step surface 21 of the bottom case 2. In addition, the downward frictional force generated in the seal lip 12 in the process in which the bottom case 2 is displaced upward with respect to the fork pipe 3 does not act as a removal load.

  Further, for example, in the case of a structure in which a reinforcing metal ring is embedded in a rubber elastic body as in the conventional dust seal 100 shown in FIGS. 3 and 4 described above, the metal ring is used for vulcanization molding in manufacturing. A plurality of molding marks were formed by pressing protrusions for positioning and fixing in the mold, and a part of the metal ring was exposed from the molding marks, which caused the occurrence of rust. The structured dust seal 1 is made of a single rubber elastic body, and does not have rust because there is no metal ring.

  The reduction in rigidity of the dust seal 1 due to the abolition of the metal ring for reinforcement causes the radial thickness of the base portion 11 to be thicker than that of the seal lip 12, the encapsulating portion 13, and the engaging convex portion 14. This can be sufficiently compensated by the base 11 being brought into contact with the upper end surface 25 of the bottom case 2.

  In order to attach the dust seal 1 to the bottom case 2, the engaging convex portion 14 of the dust seal 1 and the enveloping portion 13 are pushed so as to cover the upper outer periphery of the bottom case 2. In the process, first, the chamfer 14c at the lower end of the engaging convex portion 14 interferes with the chamfer 24 at the upper end of the bottom case 2, so that the engaging convex portion 14 is expanded in diameter and deformed. Then, the enveloping part 13 is extrapolated to the outer peripheral surface 22 on the large diameter side. Then, by pushing until the abutting surface 11a of the base portion 11 abuts with the upper end surface 25 of the bottom case 2, the engaging convex portion 14 reaches the smaller diameter side than the step surface 21 of the bottom case 2, so that the latching surface 14b is It can be set as the state latched by the level | step difference surface 21. FIG.

  Further, in the process of extrapolating the engaging convex portion 14 and the enveloping portion 13 of the dust seal 1 to the bottom case 2, the inside of the engaging convex portion 14 and the large-diameter outer peripheral surface 22 of the bottom case 2 that are in close contact with each other. Since an air discharge path by the air discharge groove 15 is secured between the peripheral surface 14a, the air existing on the inner periphery of the dust seal 1 is easily discharged, and therefore, an escape load is generated due to compression of the internal air. Therefore, the mounting operation can be easily performed.

  In addition, since the dust seal 1 is made of a single rubber elastic body, it can be easily mounted with a small load and can be easily removed for replacement.

DESCRIPTION OF SYMBOLS 1 Dust seal 11 Base 11a Abutting surface 12 Seal lip 13 Enveloping part 14 Engaging convex part (fixing part)
14a Inner peripheral surface 14b Holding surface 15 Air discharge groove 2 Bottom case (outer peripheral member)
21 Stepped surface 3 Fork pipe (inner peripheral member)

Claims (3)

  A base made of a single rubber elastic body and having an abutting surface capable of intimately engaging with the upper end surface of the outer peripheral member, and an inner portion extending upward from the base and inserted into the inner periphery of the outer peripheral member so as to be capable of relative movement. A seal lip that is slidably brought into close contact with the outer peripheral surface of the peripheral member, an enveloping portion that extends in a cylindrical shape downward from the outer diameter side of the abutting surface of the base, and the outer periphery provided on the enveloping portion A dust seal comprising: a fixing portion that can be fixed to the outer periphery of the member.   The dust seal according to claim 1, wherein the fixing portion includes an engaging convex portion that can be engaged with a downward surface formed on the outer peripheral surface of the outer peripheral member.   The dust seal according to claim 1, wherein a continuous air discharge groove is formed from the inner peripheral surface of the fixed portion to the abutting surface of the base portion.

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