JP2017082900A - Valve stem seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure lubrication between a valve stem and a valve guide while improving fuel economy by reducing a fastening force of the valve stem.SOLUTION: A valve stem seal (1) seals a valve stem which makes a cylinder and a port communicate with each other, and blocks the communication, and a valve guide into which the valve stem is reciprocally inserted. The valve stem seal is arranged at the valve guide, and comprises an annular reinforcing ring (2) with an axial line (x) as a center, and an elastic body part (3) attached to the reinforcing ring with an axial line as a center. The elastic body part has a fitting part (31) which is pressed between the reinforcing ring and the valve guide, and an annular seal part (32) with an axial line as a center which abuts on the valve stem at the inside of a radial direction. The seal part has a plurality of salient parts (35) which are salient to the outside of the radial direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a valve stem seal.

Conventionally, in an internal combustion engine, a valve stem seal has been used to seal a space between a valve stem and a valve guide of an intake / exhaust valve that reciprocates between a cam side and a cylinder side. The valve stem seal suppresses damage to the valve guide and the valve stem caused by a small amount of oil leakage (amount of lubricating oil supplied between the valve stem and the valve guide) during operation of the internal combustion engine. In order to prevent problems such as the generation of white smoke due to the large amount of leakage, adjust the amount of oil leakage and lubricate the valve guide and valve stem to smoothly move the valve stem back and forth. While being supplied, the lubricating oil is prevented from flowing into the port and cylinder (combustion chamber).
FIG. 5 is a cross-sectional view showing a state in which the conventional valve stem seal 100 is attached to the valve guide 101 together with the valve stem 102. The valve stem seal 100 is made of a metal reinforcing ring 103, an elastic body portion 104 made of an elastic body such as rubber, and the elastic body portion 104 in a direction toward the axis x. And an urging spring 105. The spring 105 tightens the elastic body portion 104 from the outside, thereby increasing the force of pressing the valve stem 102 by the seal lip 106 of the elastic body portion 104 and improving the sealing performance (see, for example, Patent Document 1).

JP 2009-108827 A

In recent years, in order to further improve the fuel efficiency of an internal combustion engine, there is an increasing demand (reduction in torque) for reducing the tightening force of the valve stem seal 100 against the valve stem 102 in accordance with the vehicle type.
In response to such a demand, it is conceivable to make the elastic body portion 104 thinner.
However, when such a configuration is adopted, the rigidity of the elastic body portion 104 is reduced, and the elastic body portion 104 may be damaged by the reciprocating motion of the valve stem 102. Furthermore, since the tightening force of the valve stem 102 by the elastic body portion 104 may decrease to an unacceptable level, when pressure (back pressure) from the cylinder side based on the port pressure is applied to the seal lip 106. In addition, the seal lip 106 may be separated from the valve stem 102. Further, the tightening force of the valve stem 102 of the elastic body portion 104 greatly depends on the spring 105, and it is difficult to adjust the tightening force of the elastic body portion 104 by the spring 105 in accordance with the vehicle type.

  Accordingly, the present invention has been made in view of the above-described problems, and a valve capable of ensuring lubrication between the valve stem and the valve guide while reducing the tightening force of the valve stem and improving fuel efficiency. An object is to provide a stem seal.

  In order to solve the above-described problems, the present invention aims to seal a valve stem of a valve for communicating and blocking between a cylinder and a port, and a valve guide into which the valve stem is reciprocally inserted. A valve stem seal provided on a guide, comprising: an annular reinforcing ring centered on an axis; and an elastic body part attached to the reinforcing ring about the axis, wherein the elastic body part is the reinforcing member A fitting portion that is pressed between the ring and the valve guide; and an annular seal portion that is in contact with the valve stem on the radially inner side and that is centered on the axis. It has the some protrusion part which protrudes outside, It is characterized by the above-mentioned.

  The plurality of protrusions are preferably provided at equal intervals in the circumferential direction.

  Each protrusion preferably has the same thickness along the radial direction.

  It is preferable that the length along the outer periphery of each of the plurality of protrusions is equal.

  It is preferable that the protrusion is widened in the circumferential direction from the radially inner side to the radially outer side.

  It is preferable that the outer peripheral surface of the seal portion is inclined so as to approach the axis line from the cylinder side toward the cam side.

  According to the present invention, it is possible to ensure lubrication between the valve stem and the valve guide while reducing the tightening force of the valve stem and improving fuel efficiency.

It is a top view of the valve stem seal concerning an embodiment of the invention. It is sectional drawing along the axis line of the valve stem seal in the II-II line | wire of FIG. FIG. 3 is a cross-sectional view along the axis of the valve stem seal taken along line III-III in FIG. 1. It is a longitudinal cross-sectional view of the sealing structure using a valve stem seal. It is a longitudinal cross-sectional view of the sealing structure using the conventional valve stem seal.

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, embodiment shown below is one illustration and can take a various form in the scope of the present invention.

<Valve stem seal>
FIG. 1 is a plan view of the valve stem seal 1. FIG. 2 is a cross-sectional view along the axis x in the II-II line shown in FIG. FIG. 3 is a cross-sectional view along the axis x in the III-III line shown in FIG. FIG. 4 is a cross-sectional view taken along an axis x for showing a schematic structure of a sealing structure using the valve stem seal 1 in a state where it is used in an internal combustion engine.

The valve stem seal 1 is intended to seal between the valve guide 4 and the valve stem 5 in the valve train of the internal combustion engine. That is, between the valve stem 5 of the valve for communicating and blocking between the cylinder and the port, and the valve guide 4 in which one end through which the valve stem 5 is inserted faces the cam side and the other end faces the cylinder side. It is intended to seal the space. As shown in FIG. 4, the valve stem seal 1 is fitted and attached so as to cover one end of the valve guide 4 facing the cam side.
Here, “sealing” means a space between the valve guide 4 and the valve stem 5 at one end of the valve guide 4 on the cam side so that the back pressure from the combustion chamber is not transmitted from the cylinder side to the cam side. In order to lubricate the sliding surfaces of the valve guide 4 and the valve stem 5, the amount of the lubricating oil is adjusted so that the lubricating oil does not enter the combustion chamber, and the lubricating oil is supplied to the valve guide 4 and the valve guide. Supplying to the sliding surface with the stem 5 is said.

2 and 3, the valve stem seal 1 is attached to the reinforcing ring 2 with the metal ring-shaped reinforcing ring 2 centering on the axis x and the axis x similar to the center of the reinforcing ring 2. And an annular elastic body portion 3 formed of an elastic body.
The reinforcing ring 2 is manufactured, for example, by pressing or forging. The elastic body portion 3 is made of, for example, a rubber material such as fluorine rubber, and is molded by crosslinking (vulcanization) molding using a molding die. At the time of this cross-linking molding, the reinforcing ring 2 is disposed in the mold, and the elastic body portion 3 is bonded to the reinforcing ring 2 by cross-linking and formed integrally with the reinforcing ring 2.

[Reinforcement ring]
The reinforcing ring 2 has a substantially L-shaped cross section (hereinafter also referred to as a cross sectional shape) along the axis x, and a cylindrical cylindrical portion 21 extending in the axis x direction, And a hollow disk-shaped flange portion 22 extending from the upper end portion toward the axis x.

[Elastic body part]
The elastic body portion 3 is a ring-shaped portion around the axis line x that is in contact with the fitting portion 31 pressed between the reinforcing ring 2 and the valve guide 4 and the valve stem 5 on the inner peripheral side of the elastic body portion 3. And a seal portion 32. The elastic body portion 3 includes a cover portion 33 that covers the flange portion 22 of the reinforcing ring 2, and the cover portion 33 connects the fitting portion 31 and the seal portion 32 in the elastic body portion 3. The fitting part 31, the seal part 32, and the cover part 33 are integrally formed by the same elastic body.

(Fitting portion)
The fitting portion 31 is a portion that functions because the valve stem seal 1 is fitted and fixed to the valve guide 4. The fitting portion 31 extends along the axis x on the radially outer side of the valve stem seal 1 and is reinforced. The cylindrical portion 21 of the ring 2 is covered from the inside in the radial direction. The thickness of the fitting portion 31 in the radial direction is set to a predetermined thickness so that a predetermined fitting force is generated when the fitting portion 31 is fitted to the valve guide 4. The peripheral surface of the fitting portion 31 may be set to the above-described predetermined thickness in a partial range in the axis x direction, and the fitting portion 31 may be a peripheral surface in the entire range in the axis x direction. May be set to the predetermined thickness.

(Seal part)
The seal portion 32 is a portion that forms a tightening force with respect to the valve stem 5 in the attached state of the valve stem seal 1, has a substantially truncated cone shape with a hollow cross-sectional shape, and has a plan view as shown in FIG. 1. Therefore, the wall thickness is uneven in the circumferential direction. The seal portion 32 includes an annular portion 34 centering on the axis x, a plurality of protruding portions 35, and a seal lip 36. The annular portion 34, the protruding portion 35, and the seal lip 36 are integrally formed.

  The annular portion 34 has an outer peripheral surface 34 a between portions where the protruding portions 35 are not provided, that is, between the adjacent protruding portions 35 and 35. As shown in FIG. 2, the outer peripheral surface 34a of the annular portion 34 is inclined so as to approach the axis x as it goes from the lower end edge 34c to the upper end edge 34b in the direction of the axis x. Therefore, the seal part 32 has a thick part having a thick radial thickness corresponding to the protruding part 35 and a thin part having only a circular part 34.

As shown in FIG. 1, the protruding portion 35 is a portion (thick wall portion) protruding radially outward from the annular portion 34, and the wall thickness of the seal portion 32 is increased so that the wall thickness is not increased in the circumferential direction. This is a uniform part. In FIG. 1, four protrusions 35 are provided, and a pair of protrusions 35 are provided so as to face each other on the diameter.
The protruding portions 35 protrude radially outward from the outer periphery of the annular portion 34, and the adjacent protruding portions 35 are provided at equal intervals. As shown in FIG. 2, the outer peripheral surface 35a of the protrusion 35 is inclined so as to approach the axis x as it goes from the lower end edge 35c on the lower side to the upper end edge 35b on the upper side in the direction of the axis x.

The upper end edge 34b of the annular portion 34 and the upper end edge 35b of the protruding portion 35 are at the same height in the axis x direction, and the upper end surfaces of the annular portion 34 and the protruding portion 35 are flush with each other. Further, the lower end edge 35c of the annular portion 34 and the lower end edge 35c of the projecting portion 35 are also at the same height position in the axis x direction.
An upper end edge 35b of the projecting portion 35 is located radially outside the upper end edge 34b of the annular portion 34, and a lower end edge 35c of the projecting portion 35 is located more radially outward than the lower end edge 34c of the annular portion 34. In addition, the outer peripheral surface 35a of the projecting portion 35 and the outer peripheral surface 34a of the annular portion 34 have the same inclination angle with respect to the axis x. That is, each protrusion 35 has a uniform diameter from the annular portion 34 at any height position along the axis x from the outer peripheral surface 34a of the portion (thin wall portion) where the protrusion 35 of the annular portion 34 is not provided. The same thickness protrudes outward in the direction.
Moreover, the outer peripheral surface 35a of each protrusion part 35 is extended only the same length along the circumferential direction, as shown in FIG. More specifically, the outer peripheral surface 35a of each protrusion 35 has the same circumferential length in the circumferential direction at the same height position in the axis x direction.
Furthermore, the protrusion part 35 is expanded in the circumferential direction and protrudes from the radially inner side to the radially outer side. The width of the protruding portion 35 in the circumferential direction gradually increases from the portion connected to the annular portion 34 radially outward toward the lower end edge 35c, and the protruding portion 35 has a substantially fan shape in plan view. .

  As shown in FIGS. 2 and 3, the seal lip 36 is formed in an annular shape around the axis line x on the inner peripheral surface of the annular portion 34. The front end portion of the seal lip 36 protrudes toward the axis x, and has a wedge shape whose cross-sectional shape is convex toward the inner peripheral side. The seal lip 36 abuts on the valve stem 5 inserted as described later on the radially inner side of the annular portion 34.

(Cover part)
As shown in FIGS. 2 and 3, the cover portion 33 includes an upper cover portion 33 a that covers the upper side of the flange portion 22 of the reinforcing ring 2, and a lower cover portion 33 b that covers the lower side of the flange portion 22. Yes. When the valve stem seal 1 is fitted to the valve guide 4, the lower cover portion 33 b comes into contact with the end surface facing the upper side of the valve guide 4 so that the surface facing the lower side of the lower cover portion 33 b contacts the valve guide 4. The thickness in the direction of the axis x may be set at least in part so that the valve stem seal 1 is positioned with respect to 4.

<Sealing structure>
Below, the sealing structure 10 which seals between the valve stem 5 and the valve guide 4 is demonstrated using FIG.

As shown in FIG. 4, the sealing structure 10 includes the valve stem seal 1 and the valve guide 4, and the valve stem seal 1 is fitted to one end of the valve guide 4 on the cam side.
The valve guide 4 is formed in a cylindrical shape. The valve guide 4 is formed with a guide hole 41 which is a through hole extending along the axis x direction into which the valve stem 5 of the valve is inserted so as to freely reciprocate in the axis x direction. The guide hole 41 extends between one end of the valve guide 4 on the cam side and the other end of the valve guide 4 on the cylinder side, and the inner diameter of the guide hole 41 is slightly larger than the outer diameter of the valve stem 5. Yes.

In a state where the sealing structure 10 is configured, the valve stem 5 of the valve is inserted into the guide hole 41 of the valve guide 4 from the cylinder side and is inserted into the valve stem seal 1. The valve stem 5 reciprocates in the axis x direction by a cam (not shown). In the valve stem seal 1, the tip end portion of the seal lip 36 abuts the outer peripheral surface 51 of the valve stem 5 so that the valve stem 5 can slide freely.
Further, an annular space g is formed between the guide hole 41 of the valve guide 4 and the outer peripheral surface 51 of the valve stem 5 so that the valve stem 5 can reciprocate in the guide hole 41 of the valve guide 4. It has become.
When one end of the valve guide 4 is press-fitted inside the cylindrical portion 21 of the reinforcing ring 2 and the fitting portion 31 of the elastic body portion 3, the fitting portion 31 is connected to the cylindrical portion 21 of the reinforcing ring 2 and the valve guide 4. It is compressed between the outer peripheral surfaces and generates a predetermined magnitude of a fitting force that is a radial force. With this fitting force, the valve stem seal 1 is fitted and fixed to the valve guide 4. The thickness of the fitting portion 31 in the radial direction is set to a predetermined thickness so that the predetermined fitting force is generated.

The tip of the seal lip 36 comes into contact with the outer peripheral surface 51 of the valve stem 5 to seal the space g from the cam side to which the lubricating oil is supplied. The tip of the seal lip 36 has a predetermined amount of lubrication. The oil leaks from the tip of the seal lip 36, and the leaked lubricating oil is supplied to the space g. The predetermined leakage amount of the lubricating oil is an amount such that an oil film is formed in the space g and the valve stem 5 can smoothly reciprocate with respect to the guide hole 41 of the valve guide 4.
The seal portion 32, particularly the protrusion portion 35, has a valve so that such an appropriate amount of lubricating oil leaks from between the front end portion of the seal lip 36 and the outer peripheral surface 51 of the valve stem 5 and is supplied to the space g. A clamping force having a predetermined size is generated on the stem 5. A plurality of protruding portions 35 are provided at equal intervals on the outer periphery of the annular portion 34, and thick portions and thin portions are alternately arranged in the circumferential direction on the seal portion 32.
As shown in FIG. 1, the four protrusions 35 are provided at equal intervals in the circumferential direction, and the valve stem 5 is sandwiched from both sides in the diametrical direction. Tightening is possible. In addition, the seal portion 32 as a whole generates a predetermined tightening force on the valve stem 5 by the protrusion 35 and generates contraction in a portion where the protrusion 35 is not provided, so that the valve stem 5 can follow the reciprocating motion. Demonstrate sex.
The tightening force depends on the type of vehicle using the valve stem seal 1, the protruding amount of the protruding portion 35 from the annular portion 34 on the radially outer side, the circumferential length of the protruding portion 35 in the circumferential direction, and the circumference of the protruding portions 35. Determined by at least one of the intervals in the direction.

<Action, effect>
According to the valve stem seal 1 having the above-described configuration, the seal portion 32 has a protruding portion 35, that is, a thick portion having a high rigidity by increasing the wall thickness by protruding radially outward, and other walls. A thin portion having a small thickness but excellent followability is provided. For example, an elastic body can be used without using a spring 103 attached to the elastic body portion 102 like the conventional valve stem seal 100 shown in FIG. The part 3 itself can tighten the valve stem 5 with a predetermined tightening force. Further, the tightening force by the valve stem seal 1 can be easily adjusted by increasing the number of protrusions 35 or increasing the size of each protrusion 35. This makes it possible to supply an appropriate amount of lubricating oil from the cam side while suppressing dissociation of the seal lip 36 from the valve stem 5 due to back pressure.
Further, since the plurality of projecting portions 35 are provided at equal intervals in the circumferential direction, when the valve stem seal 1 is attached, the valve guide seal 4 is attached to the valve guide 4 and the valve stem 5 in the circumferential direction of the valve stem seal 1. There is no need to consider the mounting angle, and the labor of the mounting work can be reduced. Further, the clamping force of the valve stem seal 1 against the valve stem 5 is also provided uniformly over the outer peripheral surface 51 of the valve stem 5, so that even when the valve stem 5 is eccentric and reciprocates, The flexible followability of the seal lip 36 can be obtained, and excessive stress concentration at a predetermined portion of the seal lip 36 can be suppressed, so that uneven wear on the seal lip 36 can be suppressed. .
In addition, each of the plurality of protruding portions 35 protrudes from the outer peripheral surface of the portion of the seal portion 32 that does not include the protruding portion 35 by the same distance in the radial direction, and each of the outer peripheral surfaces 35a of the plurality of protruding portions 35 is Since it extends by the same length in the circumferential direction, the tightening force with respect to the valve stem 5 at each protrusion 35 of the valve stem seal 1 becomes more even, and the occurrence of stress concentration can be further suppressed. Further, the tightening force can be easily adjusted according to the vehicle type to which the valve stem seal 1 is attached.

<Others>
The present invention is not limited to the above embodiment. For example, the protrusion part 35 should just be provided with two or more, and the quantity, a magnitude | size, and a shape are not specifically limited. Further, as long as a predetermined tightening force can be secured, the outer peripheral surface 34a of the annular portion 34 and the outer peripheral surface 35a of the protruding portion 35 may not be inclined and may extend in parallel to the axis x. Further, the width in the circumferential direction of the protruding portion 35 may be constant from the radially inner side to the outer side.

DESCRIPTION OF SYMBOLS 1 Valve stem seal 2 Reinforcement ring 3 Elastic body part 4 Valve guide 5 Valve stem 10 Sealing structure 31 Fitting part 32 Seal part 34 Annular part 34a Outer peripheral surface 35 Protruding part 35a Outer peripheral surface 36 Seal lip x Axis line

Claims (6)

A valve stem seal provided in the valve guide for sealing a valve stem of a valve for communicating and blocking between a cylinder and a port, and a valve guide into which the valve stem is reciprocally inserted.
An annular reinforcing ring centered on the axis;
An elastic body portion attached to the reinforcing ring around the axis,
The elastic body portion includes a fitting portion that is pressed between the reinforcing ring and the valve guide, and an annular seal portion that is in contact with the valve stem on the radially inner side and that is centered on the axis. ,
The valve stem seal according to claim 1, wherein the seal part has a plurality of projecting parts projecting radially outward.   The valve stem seal according to claim 1, wherein the plurality of protrusions are provided at equal intervals in the circumferential direction.   The valve stem seal according to claim 1 or 2, wherein each protrusion has the same thickness along the radial direction.   The valve stem seal according to any one of claims 1 to 3, wherein each of the plurality of protrusions has an equal length along the outer periphery.   The valve stem seal according to any one of claims 1 to 4, wherein the protrusion is widened in a circumferential direction from a radially inner side to a radially outer side.   The valve according to any one of claims 1 to 5, wherein an outer peripheral surface of the seal portion is inclined so as to approach the axis line from the cylinder side toward the cam side. Stem seal.

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