JP2005201313A - Valve stem seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve stem seal 1 in which a seal lip 3a is not excessively abraded at an early stage even under dry and high-temperature conditions and which can stably seal a sealing fluid such as exhaust gas. <P>SOLUTION: The valve stem seal 1 has the seal lip 3a which is arranged to one end part of a valve stem guide and freely slidably brought into close contact with the peripheral face of the valve stem. At least three annular protruding parts 4, 5, and 6, which are freely slidably brought into close contact with the peripheral face of the valve stem, is provided to the inner peripheral face of the seal lip 3a. An annular weir part 7 for holding grease is provided to the valve stem guide side of the annular protruding parts 4, 5, and 6. The inner diameter dimensions of the annular protruding parts 4, 5, and 6 are formed so as to be mutually equal. The dimension of the annular weir part 7 is set so as to form a minute radial clearance in-between the peripheral face of the valve stem. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a valve stem seal used for sealing exhaust gas or the like in an EGR exhaust recirculation valve or the like.

  In an EGR device described in Japanese Patent Application Laid-Open No. 2003-293865 (Patent Document 1) or Japanese Patent Application Laid-Open No. 2003-35167 (Patent Document 2), a valve stem (valve shaft) in the exhaust gas recirculation valve and a stroke thereof are used. It is necessary to prevent the exhaust gas from leaking from between the valve stem guide (valve bearing) that is freely supported. For this reason, as shown in FIG. A valve stem seal 53 having a seal lip 54 slidably in close contact with the peripheral surface of the valve stem 52 has been developed.

  However, according to this conventional valve stem seal 53, since no special measures are taken with respect to the sliding of the seal lip 54 on the peripheral surface of the valve stem 52 under dry and high temperature conditions, the seal lip 54 has an early stage. There is a disadvantage that excessive wear occurs.

JP 2003-293865 A JP 2003-35167 A

  In view of the above, the present invention provides a valve stem seal capable of stably sealing a sealing fluid such as exhaust gas without causing excessive wear of the seal lip at an early stage even under dry and high temperature conditions. The purpose is to do.

  In order to achieve the above object, a valve stem seal according to the present invention includes a seal lip disposed at one end of a valve stem guide and slidably in close contact with a peripheral surface of the valve stem. Provided on the inner peripheral surface at least three annular protrusions slidably in contact with the peripheral surface of the valve stem, provided on the valve stem guide side of the annular protrusion is an annular weir portion for holding grease, The annular convex portions are formed to have the same inner diameter, and the annular weir portion forms a minute radial clearance with the peripheral surface of the valve stem.

  Like the valve stem seal of the present invention having the above-described configuration, when at least three annular protrusions that are slidably in close contact with the peripheral surface of the valve stem are provided on the inner peripheral surface of the seal lip, Grease for lubricating the sliding portion can be stored in the annular recess formed therebetween. The reason why the number of annular projections formed is at least three, that is, three or more, is to disperse the interference of the seal lip with respect to the valve stem and reduce the contact pressure at each annular projection. Since the inner diameter dimensions of the parts are the same, the contact pressure can be equalized. The seal lip in which the interference is dispersed and equalized in each annular convex portion generally exhibits the feature that it is difficult to wear by sliding.

  Further, since the annular dam portion for holding the grease is provided on the valve stem guide side of the annular convex portion, the grease can be stored in the space between the annular convex portion and the annular dam portion, Since a minute radial clearance is formed between the peripheral surfaces of the valve stem, it is possible to suppress the annular weir portion from scraping out grease during the stroke of the valve stem.

  The present invention has the following effects.

  That is, according to the valve stem seal of the present invention, the lubricating action by the grease can be expected as described above, and the interference of the seal lip with respect to the valve stem is dispersed and equalized, and thus, It is possible to effectively prevent the seal lip from being excessively worn at an early stage even under dry and high temperature conditions.

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

  FIG. 1 shows a half cut section of a valve stem seal 1 according to an embodiment of the present invention in a free (before mounting) state. FIG. 2 shows a half-cut section of the seal 1 mounted.

  The valve stem seal 1 according to this embodiment seals exhaust gas in an EGR exhaust recirculation valve, and is configured as follows.

  That is, first, a metal mounting ring (also referred to as an outer ring) 2 attached to the outer peripheral surface of one axial end portion (upper end portion in the figure) of a valve stem guide (see FIG. 2) 21 as an attachment member is provided. An elastic body (also referred to as packing) 3 made of rubber-like elastic material is vulcanized and bonded to the mounting ring 2, and the elastic body 3 surrounds a valve stem (see FIG. 2) 22 that is a sliding counterpart member. A seal lip 3a that is slidably in contact with the surface and a stationary seal portion 3b that is in static contact with the outer peripheral surface of the valve stem guide 21 are integrally formed.

  The mounting ring 2 is formed by integrally molding a flange portion 2b at one end in the axial direction of the cylindrical portion 2a so as to be radially inward, and is formed into a substantially L-shaped half-cut section. A seal lip 3a is formed on the latter flange portion 2b. Is vulcanized and bonded, and the stationary seal portion 3b is vulcanized and bonded to the inner peripheral surface of the former cylindrical portion 2a.

  The seal lip 3a is formed in a cylindrical shape from the inner peripheral end of the flange portion 2b of the mounting ring 2 toward one side in the axial direction (upward in the figure), and a valve stem is formed on the inner peripheral surface of the seal lip 3a. Three annular protrusions 4, 5, and 6 are provided on the peripheral surface of 22 so as to be slidably in contact with each other, and grease is formed on the valve stem guide 21 side (upper and lower sides in the figure) of the annular protrusions 4, 5, and 6. One annular weir portion 7 is provided for holding the. Further, an annular mounting groove 8 is provided on the outer peripheral surface of the seal lip 3a, and a garter spring (also simply referred to as a spring) 9 for adjusting the interference is fitted into the mounting groove 8.

  The three annular projections 4, 5, and 6 are each formed in a substantially semicircular cross section, have substantially the same cross sectional shape, and have the same inner diameter dimension φA in the free state. This inner diameter dimension φA is set slightly smaller than the outer diameter dimension φC of the valve stem 22 (see FIG. 2).

  Further, the inner diameter dimension φB of the annular weir portion 7 is set to be slightly larger than the outer diameter dimension φC of the valve stem 22, and as a result, as shown in FIG. And a small radial clearance c is formed between the valve stem 22 and the peripheral surface of the valve stem 22.

  In the valve stem seal 1 configured as described above, when the valve stem 22 strokes during the operation of the valve, the seal lip 3a slides with respect to the peripheral surface of the valve stem 22, so that the sliding lip 3a is subjected to sliding wear. Although there is concern about the occurrence, sliding wear is reduced by the following countermeasures by the above configuration.

  That is, since the three annular convex portions 4, 5, and 6 that are slidably in close contact with the peripheral surface of the valve stem 22 are provided on the inner peripheral surface of the seal lip 3a, the annular convex portions 4, 5 are provided. , 6 are brought into close contact with the peripheral surface of the valve stem 22, annular recesses 10, 11 are formed between the annular projections 4, 5, 6 as shown in FIG. 10 and 11 can store grease for sliding portion lubrication (not shown). The grease is previously injected before the valve is operated. Therefore, the sliding portion is lubricated by the grease stored in the annular recesses 10 and 11.

  Further, since the three annular protrusions 4, 5, 6 are provided, the interference of the seal lip 3a with respect to the valve stem 22 is dispersed to reduce the contact pressure at each of the annular protrusions 4, 5, 6. In addition, since the inner diameters φA of the annular protrusions 4, 5, and 6 are formed to be the same, the contact pressure can be equalized. Therefore, since the interference is dispersed and equalized and reduced in each of the annular convex portions 4, 5, and 6, the seal lip 3a itself has a characteristic that it is difficult to slide and wear in shape. According to the knowledge of the inventors of the present application, the number of the annular protrusions 4, 5, 6 is not enough to be two, and must be three or more from the viewpoint of balance with the size of the interference.

  Further, since the annular weir portion 7 for holding the grease is provided on the valve stem guide 21 side of the annular convex portions 4, 5, 6 and so Grease can also be stored in the space 12. Therefore, the sliding portion is also lubricated by the grease stored in the space 12.

  Furthermore, since the annular weir portion 7 is not in contact with the valve stem 22 and a minute radial clearance c is formed between the annular weir portion 7 and the valve stem 22, Even if the annular weir portion 7 moves relatively, the grease is not scraped off. Accordingly, since the grease supplied to the sliding portion is held for a long period without being scraped, the lubricating action by the grease can be exerted for a long period.

  Combined with the above effects, according to the valve stem seal 1, it is possible to prevent the seal lip 3a from being excessively worn early even under dry and high temperature conditions. Can be sealed.

FIG. 3 is a half sectional view of a valve stem seal according to an embodiment of the present invention. Half cut sectional view showing the valve stem seal installed Explanatory drawing of valve stem seal according to conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Valve stem seal 2 Mounting ring 2a Cylindrical part 2b Flange part 3 Elastic body 3a Seal lip 3b Static seal part 4, 5, 6 Annular convex part 7 Annular dam part 8 Mounting groove 9 Garter spring 10, 11, Annular concave part 12 Space 21 Valve stem 22 Valve stem guide

Claims (1)

In the valve stem seal (1) having a seal lip (3a) disposed at one end of the valve stem guide (21) and slidably in close contact with the peripheral surface of the valve stem (22),
Provided on the inner peripheral surface of the seal lip (3a) are at least three annular protrusions (4), (5) and (6) which are slidably in close contact with the peripheral surface of the valve stem (22). (4) An annular weir portion (7) for holding grease is provided on the valve stem guide (21) side of (5) and (6),
The annular protrusions (4), (5), and (6) are formed to have the same inner diameter dimension (φA),
The annular stem weir (7) forms a minute radial clearance (c) between the peripheral surface of the valve stem (22) and the valve stem seal.

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