JP6677005B2 - Valve stem seal and sealing structure - Google Patents

Description

  The present invention relates to a valve stem seal fixed to a valve stem guide for guiding a valve stem and a sealing structure.

  In an intake / exhaust valve mechanism of an internal combustion engine, a valve stem seal for sealing an annular gap between an insertion hole provided in a valve stem guide and a valve stem inserted into the insertion hole is provided. A valve stem seal according to a conventional example will be described with reference to FIGS. FIG. 3 is a schematic sectional view of a valve stem seal according to a conventional example. FIG. 4 is a schematic cross-sectional view showing a state in which a conventional valve stem seal is attached to a valve stem guide.

  The valve stem (not shown) is configured to be inserted through an insertion hole provided in the valve stem guide 300 and to be guided by the inner peripheral surface of the insertion hole. In order to seal the lubricating oil in the lubricating oil chamber while supplying an appropriate amount of lubricating oil to the extent that an oil film is formed in the annular gap between the insertion hole provided in the valve stem guide 300 and the valve stem. , A valve stem seal 500 is provided.

  The valve stem seal 500 according to this conventional example includes a reinforcing ring 510 and a seal body 520 made of a rubber-like elastic body and provided integrally with the reinforcing ring 510. The seal body 520 is provided on the inner peripheral surface side of the cylindrical body portion of the reinforcing ring 510, and is fitted and fixed to the valve stem guide 300. 522. On the inner peripheral surface of the fitting portion 522, there is provided an annular projection 522a that fits into an annular concave portion 310 provided on the outer peripheral surface of the valve stem guide 300.

  In the valve stem seal 500 configured as described above, the inner diameter of the fitting portion 522 is set to be smaller than the outer diameter of the valve stem guide 300, so that the valve stem seal 500 fits into the valve stem guide 300. Fixed by case. Then, in order to prevent the valve stem seal 500 from coming off from the valve stem guide 300, measures are taken to increase the interference of the fitting portion 522 to the valve stem guide 300. Note that the “tightening allowance” is a difference between half the length of the outer diameter of the valve stem guide 300 and half the length of the inner diameter of the fitting portion 522.

  However, when the above-described countermeasures are taken, a part of the fitting portion 522 may be torn, and on the contrary, the valve stem seal 500 may easily come off from the valve stem guide 300. That is, as shown in FIG. 4, the valve stem seal 500 is fitted into the valve stem guide 300 in the direction of the arrow (downward) in the figure. In this fitting process, the vicinity of the inner peripheral surface of the fitting portion 522 is pulled by the frictional force in the direction (upward) opposite to the direction of the arrow in the figure. As a result, a part of the fitting portion 522 may be torn. In particular, in the case of the annular projection 522a, its inner diameter is smaller than that of other parts, and it is pulled by a large force in the direction opposite to the arrow direction in the figure by the end edge of the distal end of the valve stem guide 300. . Therefore, in particular, the annular projection 522a was apt to be partially torn. FIG. 4 shows a state in which the valve stem seal 500 is being fitted.

Japanese Utility Model Publication No. 6-40304

  An object of the present invention is to provide a valve stem seal and a sealing structure capable of suppressing detachment from a valve stem guide.

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

That is, the present invention
In a valve stem seal fixed to a valve stem guide for guiding a valve stem,
A reinforcing ring having a cylindrical body,
A seal body made of a rubber-like elastic body provided integrally with the reinforcing ring,
With
The seal body,
A seal portion slidable on the valve stem,
A fitting portion provided on the inner peripheral surface side of the body portion and fitted and fixed to the valve stem guide;
A valve stem seal comprising:
The fitting portion,
A fitting portion main body made of a rubber-like elastic body integrated with the seal portion,
The valve stem guide is provided on the distal end side in the fitting direction and is joined to the inner peripheral surface of the fitting portion main body, and has a lower frictional resistance to the valve stem guide than the fitting portion main body. , A resin fitting portion reinforcing portion having higher strength than the fitting portion main body portion,
It is characterized by having.

Further, the sealing structure of the present invention,
A valve stem, a valve stem guide for guiding the valve stem, and a valve stem seal fixed to the valve stem guide, a sealing structure comprising:
The valve stem seal includes:
A reinforcing ring having a cylindrical body,
A seal body made of a rubber-like elastic body provided integrally with the reinforcing ring,
With
The seal body,
A seal portion slidable on the valve stem,
A fitting portion provided on the inner peripheral surface side of the body portion and fitted and fixed to the valve stem guide;
With
The fitting portion,
A fitting portion main body made of a rubber-like elastic body integrated with the seal portion,
The valve stem guide is provided on the distal end side in the fitting direction and is joined to the inner peripheral surface of the fitting portion main body, and has a lower frictional resistance to the valve stem guide than the fitting portion main body. , A resin fitting portion reinforcing portion having higher strength than the fitting portion main body portion,
It is characterized by having.

In the present invention, in the fitting portion, the frictional resistance to the valve stem guide is lower on the distal end side in the fitting direction with the valve stem guide than the fitting portion main body made of a rubber-like elastic body. A resin-fitted portion reinforcing portion having higher strength than the main body portion is provided. Therefore, in the region where the fitting portion reinforcing portion is provided, when the valve stem seal is fitted into the valve stem guide, the vicinity of the inner peripheral surface of the fitting portion is pulled in a direction opposite to the fitting direction. Is suppressed. Therefore, it is suppressed that a part of the fitting portion is torn.

Further, an annular concave portion is provided on the outer peripheral surface of the valve stem guide,
An annular projection fitted into the annular recess is provided on an inner peripheral surface of the fitting section, and the annular projection may be formed on the fitting section reinforcing section.

  Thereby, it is possible to suppress tearing of a part of the annular projection.

  As described above, according to the present invention, it is possible to prevent the valve stem seal from coming off the valve stem guide.

FIG. 1 is a schematic sectional view of a valve stem seal according to an embodiment of the present invention. FIG. 2 is a schematic sectional view of the sealing structure according to the embodiment of the present invention. FIG. 3 is a schematic sectional view of a valve stem seal according to a conventional example. FIG. 4 is a schematic cross-sectional view showing a state in which a conventional valve stem seal is attached to a valve stem guide.

  Embodiments for carrying out the present invention will be illustratively described in detail below based on embodiments 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 thereto unless otherwise specified. .

(Example)
Referring to FIGS. 1 and 2, a valve stem seal and a sealing structure according to an embodiment of the present invention will be described. FIG. 1 is a schematic sectional view of a valve stem seal according to an embodiment of the present invention. FIG. 2 is a schematic sectional view of the sealing structure according to the embodiment of the present invention. 1 and 2 are cross-sectional views cut along a plane including the central axis of the valve stem seal (coinciding with the central axes of the valve stem and the valve stem guide).

<Overall configuration of sealed structure>
In particular, with reference to FIG. 2, the overall configuration of the sealing structure including the valve stem seal according to the present embodiment will be described. The valve stem 200 is configured to be inserted into an insertion hole provided in a valve stem guide 300 made of a hard material such as a metal, and to be guided by the inner peripheral surface of the insertion hole. In the figure, (O) is the lubricating oil chamber side, and (P) is the port (intake port or exhaust port) side. In order to seal the lubricating oil in the lubricating oil chamber while supplying an appropriate amount of lubricating oil to the extent that an oil film is formed in the annular gap between the insertion hole provided in the valve stem guide 300 and the valve stem 200. , A valve stem seal 100 is provided.

<Valve stem seal>
The valve stem seal 100 according to the present embodiment will be described in detail. The valve stem seal 100 includes a reinforcing ring 110 having a cylindrical body 111, and a seal body 120 made of a rubber-like elastic body and provided integrally with the reinforcing ring 110. By integral molding, the reinforcing ring 110 and the seal body 120 can be integrated. For example, the seal body 120 can be provided integrally with the reinforcing ring 110 by insert-molding the seal body 120 using the reinforcing ring 110 as an insert part. The reinforcing ring 110 is made of metal or the like, and is provided with an inward flange portion 112 on the tip side (the lubricating oil chamber side (O)) of the body portion 111.

  The seal body 120 includes a seal portion 121 slidable on the valve stem 200 and a fitting portion 122 fitted and fixed to the valve stem guide 300. The seal portion 121 is provided near the tip of the inward flange portion 112 of the reinforcing ring 110. The fitting part 122 is provided on the inner peripheral surface side of the body part 111 in the reinforcing ring 110.

  The seal part 121 extends toward the port (P) side with the first seal part 121a provided on the lubricating oil chamber side (O), the second seal part 121b provided adjacent to the first seal part 121a. A third seal portion 121c. A garter spring 130 that presses the first seal portion 121a against the valve stem 200 is provided radially outside the first seal portion 121a.

  The fitting portion 122 includes a fitting portion main body portion 122a and a fitting portion reinforcing portion 122b. The fitting portion body 122a is formed integrally with the seal portion 121, and is made of a rubber-like elastic body. The fitting portion reinforcing portion 122b is provided on the distal end side in the fitting direction (downward in FIG. 2) to the valve stem guide 300, and is joined to the inner peripheral surface of the fitting portion main body portion 122a. The fitting portion reinforcing portion 122b is made of a resin having lower frictional resistance to the valve stem guide 300 than the fitting portion main body portion 122a and having higher strength than the fitting portion main body portion 122a. PTFE (polytetrafluoroethylene) is a preferred example of the material of the fitting portion reinforcing portion 122b.

  The inner diameter of the fitting portion 122 is set smaller than the outer diameter of the valve stem guide 300. As a result, the valve stem seal 100 is fixed to the valve stem guide 300 by fitting.

  An annular recess 310 is provided on the outer peripheral surface of the valve stem guide 300. On the inner peripheral surface of the fitting portion 122 of the valve stem seal 100, an annular projection 122b1 that fits in the annular concave portion 310 is provided. This annular projection 122b1 is formed on the fitting portion reinforcing portion 122b. That is, the annular projection 122b1 is made of a resin having higher strength than the fitting portion main body 122a.

<Excellent points of the valve stem seal and the sealing structure according to the present embodiment>
In the valve stem seal 100 according to the present embodiment, in the fitting portion 122, the distal end side in the fitting direction to the valve stem guide 300 is closer to the valve stem guide 300 than the rubber-like elastic body fitting portion main body portion 122a. There is provided a fitting reinforcing portion 122b made of resin, which has a low frictional resistance with respect to and has a higher strength than the fitting portion main body 122a. Therefore, in the region where the fitting portion reinforcing portion 122b is provided, when the valve stem seal 100 is fitted into the valve stem guide 300, the vicinity of the inner peripheral surface of the fitting portion 122 is different from the fitting direction. Pulling to the opposite side is suppressed. Therefore, tearing of a part of the fitting portion 122 is suppressed.

  The annular projection 122b1 that fits into the annular concave portion 310 provided on the outer peripheral surface of the valve stem guide 300 is formed on the resin-made fitting reinforcing portion 122b. Therefore, when the valve stem seal 100 is fitted into the valve stem guide 300, it is possible to prevent a part of the annular projection 122b1 from tearing.

As described above, in order to prevent the valve stem seal 100 from being detached from the valve stem guide 300, even if a measure for increasing the interference of the fitting portion 122 with respect to the valve stem guide 300 is adopted, the fitting portion 122 ( In particular, tearing of a part of the annular projection 122b1) can be suppressed. The “tightening allowance” is a difference between half the length of the outer diameter of the valve stem guide 300 and half the length of the inner diameter of the fitting portion 122.

  Therefore, the valve stem seal 100 is fixed by fitting to the valve stem guide 300 in a stable state. Further, the locking force of the annular projection 122b1 with respect to the annular recess 310 is sufficiently obtained. As described above, the valve stem seal 100 can be prevented from coming off the valve stem guide 300.

  Here, as described above, the fitting portion reinforcing portion 122b is joined to the inner peripheral surface of the fitting portion main body portion 122a. The manner of joining the fitting portion reinforcing portion 122b to the fitting portion main portion 122a is not limited. For example, bonding by fitting, bonding by bonding, or bonding by baking may be used. Here, a specific example in the case of performing bonding by baking will be briefly described. First, the fitting portion reinforcing portion 122b made of PTFE is manufactured by molding, and the outer peripheral surface of the fitting portion reinforcing portion 122b is subjected to a surface treatment for improving the adhesiveness. Specifically, a chemical surface treatment (base treatment) is performed on the outer peripheral surface of the fitting portion reinforcing portion 122b using a substance such as tetrahydrofuran (THF), metallic sodium, or naphthalene. Thereafter, an adhesive is applied to the outer peripheral surface of the fitting portion reinforcing portion 122b. Then, in a state where the fitting portion reinforcing portion 122b is arranged in the molding die, an uncrosslinked rubber material is poured, and the seal portion 121 and the fitting portion main body portion 122a are crosslinked. Thereby, the fitting portion main body portion 122a and the fitting portion reinforcing portion 122b are joined by baking. The term “joining” includes a configuration in which a resin material such as PTFE is coated on the fitting portion main body (for example, an organic solvent liquid in which PTFE particles are dispersed) is applied. Absent. In the case of coating, particles such as PTFE are present on the surface, but are deformed together with the fitting portion main body 122a made of a rubber-like elastic body, so that the above-mentioned effects cannot be sufficiently obtained.

REFERENCE SIGNS LIST 100 Valve stem seal 110 Reinforcement ring 111 Body part 112 Inward flange part 120 Seal body 121 Seal part 121a First seal part 121b Second seal part 121c Third seal part 122 Fitting part 122a Fitting part main part 122b Fitting part Reinforcing part 122b1 Annular projection 130 Garter spring 200 Valve stem 300 Valve stem guide 310 Annular recess

Claims (4)

In a valve stem seal fixed to a valve stem guide for guiding a valve stem,
A reinforcing ring having a cylindrical body,
A seal body made of a rubber-like elastic body provided integrally with the reinforcing ring,
With
The seal body,
A seal portion slidable on the valve stem,
A fitting portion provided on the inner peripheral surface side of the body portion and fitted and fixed to the valve stem guide;
A valve stem seal comprising:
The fitting portion,
A fitting portion main body made of a rubber-like elastic body integrated with the seal portion,
The valve stem guide is provided on the distal end side in the fitting direction and is joined to the inner peripheral surface of the fitting portion main body, and has a lower frictional resistance to the valve stem guide than the fitting portion main body. , A resin fitting portion reinforcing portion having higher strength than the fitting portion main body portion,
A valve stem seal comprising:   On the inner peripheral surface of the fitting portion, there is provided an annular projection that fits into an annular recess provided on the outer peripheral surface of the valve stem guide, and the annular projection is formed on the fitting portion reinforcing portion. The valve stem seal according to claim 1, wherein: A valve stem, a valve stem guide for guiding the valve stem, and a valve stem seal fixed to the valve stem guide, a sealing structure comprising:
The valve stem seal includes:
A reinforcing ring having a cylindrical body,
A seal body made of a rubber-like elastic body provided integrally with the reinforcing ring,
With
The seal body,
A seal portion slidable on the valve stem,
A fitting portion provided on the inner peripheral surface side of the body portion and fitted and fixed to the valve stem guide;
With
The fitting portion,
A fitting portion main body made of a rubber-like elastic body integrated with the seal portion,
The valve stem guide is provided on the distal end side in the fitting direction and is joined to the inner peripheral surface of the fitting portion main body, and has a lower frictional resistance to the valve stem guide than the fitting portion main body. , A resin fitting portion reinforcing portion having higher strength than the fitting portion main body portion,
A sealing structure comprising: An annular recess is provided on the outer peripheral surface of the valve stem guide,
The inner peripheral surface of the fitting portion is provided with an annular projection that fits into the annular recess, and the annular projection is formed on the fitting portion reinforcing portion. Sealing structure.

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