JP2016223558A - Sealing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing structure which, while maintaining fitting of a valve stem seal to a valve guide via an elastic body, can inhibit the valve stem seal from coming out from the valve guide.SOLUTION: A sealing structure 1 comprises a valve guide 10 and a valve stem seal 20. The valve guide 10 comprises an annular recess 14 which is recessed to a cylinder side in an end face 12a at an end 12 on a cam side. The valve stem seal 20 comprises a reinforcement ring 30 and an elastic body part 40 mounted to the reinforcement ring 30. A seal part 41 of the elastic body part 40 integrally has a seal base portion 43, a seal lip 44, a back pressure lip 45 and a valve guide abutment lip 46. The back pressure lip 45 enters the annular recess 14 of the valve guide 10 and abuts against a valve stem. The valve guide abutment lip 46 abuts against the annular side surface 15 of the annular recess 14 of the valve guide 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealing structure, and more particularly to a sealing structure using a valve guide and a valve stem seal in an internal combustion engine.

  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 a valve that reciprocates between a cam side and a cylinder side. The valve stem seal supplies lubricating oil for smoothly sliding the valve stem between the valve guide and the valve stem, and prevents the lubricating oil from flowing into the port and the cylinder. FIG. 3 is a cross-sectional view showing a conventional valve stem seal in an attached state. As shown in FIG. 3, the conventional valve stem seal 100 includes a reinforcing ring 101 and an elastic body portion 102 formed integrally with the reinforcing ring 101 and made of an elastic body. The elastic body portion 102 includes the valve stem 110. The valve stem 110 is slidably in contact with the seal lip 103, and the back pressure lip 104 is disposed on the cylinder side of the seal lip 103. In the valve stem seal 100, the fitting portion 105 of the elastic body portion 102 is compressed between the valve guide 111 and the reinforcing ring 101 and is fitted into the valve guide 111, and the seal lip 103 comes into contact with the valve stem 110. The supply amount of the lubricating oil is controlled as described above. The back pressure lip 104 receives pressure from the cylinder side based on the port pressure (hereinafter referred to as back pressure) to suppress the back pressure applied to the seal lip 103 and to suppress deformation of the seal lip 103 due to the back pressure. Thus, the supply amount of the lubricating oil by the seal lip 103 is stabilized (for example, see Patent Document 1).

JP 2008-45654 A

  As described above, in the conventional valve stem seal 100, the back pressure applied to the seal lip 103 is suppressed by providing the back pressure lip 104. However, in recent years, due to demands for further reduction in fuel consumption of internal combustion engines, port pressure tends to increase due to engine downsizing, turbocharger mounting, etc., and back pressure tends to increase. For this reason, the conventional valve stem seal 100 may fall out of the valve guide 111 due to high back pressure.

  On the other hand, a structure is conceived in which the valve stem seal is fitted to the valve guide not through the fitting portion 105 that is an elastic body like the valve stem seal 100 but through a metal member. . However, in the case of fitting through a metal member, an assembling facility that generates a large assembling force is required because the assembling force required for fitting the valve stem seal to the valve guide is large.

  For this reason, conventionally, the valve stem seal can be prevented from coming off from the valve guide while maintaining the fitting of the valve stem seal to the valve guide via the elastic body. The sealing structure was required.

  The present invention has been made in view of the above-described problems, and its object is to prevent the valve stem seal from coming off from the valve guide while maintaining the fitting of the valve stem seal to the valve guide via the elastic body. It is in providing the sealing structure which can be suppressed.

  In order to achieve the above object, a sealing structure according to the present invention includes a valve stem of a valve for communicating and blocking between a cylinder and a port in an internal combustion engine, and one end through which the valve stem is inserted on the cam side. A sealing structure for sealing between the valve guide facing the cylinder side with the other end facing the cylinder, comprising: a valve guide; and a valve stem seal fitted to the valve guide at one end of the valve guide, The valve stem seal includes an annular reinforcing ring centered on an axis, and an annular elastic body portion centered on the axis formed from an elastic body attached to the reinforcing ring, the elastic body portion A seal lip that abuts against the valve stem, a back pressure lip that abuts against the valve stem disposed on the valve guide side from the seal lip, and the valve gas A seal portion having a valve guide abutment lip that abuts against the guide, and a fitting portion that is pressed between the reinforcing ring and the valve guide, the valve guide from one end to the other end An annular recess that is recessed in the other end direction to form an annular side surface extending in the direction, and at least a part of the back pressure lip is accommodated in the annular recess, and the valve guide abutment lip is It contacts the said annular side surface of a recessed part, It is characterized by the above-mentioned.

  In the sealing structure according to an aspect of the present invention, an annular groove that opens in the direction of the other end of the valve guide is formed between the back pressure lip and the valve guide contact lip.

  The sealing structure which concerns on 1 aspect of this invention WHEREIN: The said annular groove part has a shape where the width | variety of the direction orthogonal to the said axis line becomes narrow toward the said cam side.

  In the sealing structure according to an aspect of the present invention, the seal portion includes an annular seal base, the seal lip extends from the seal base to the cam side, and the back pressure lip is formed on the seal base. The valve guide contact lip extends from the valve guide side toward the axis, and the valve guide contact lip extends from the valve guide side of the seal base toward the annular side surface of the annular recess.

  In the sealing structure according to one aspect of the present invention, the reinforcing ring includes a cylindrical cylindrical portion extending in the axial direction, and a hollow disk-shaped flange portion extending from one end of the cylindrical portion toward the axial line, An end of the flange portion on the axis line side is located at the seal base portion in the seal portion.

  According to the sealing structure of the present invention, the valve stem seal can be prevented from coming off from the valve guide while maintaining the fitting of the valve stem seal to the valve guide via the elastic body.

It is sectional drawing which follows the axis line for showing the schematic structure of the sealing structure which concerns on embodiment of this invention. It is sectional drawing in alignment with the axis line of the sealing structure which concerns on embodiment of this invention in the state currently used in the internal combustion engine. It is sectional drawing which shows the conventional valve stem seal in an attachment state.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view taken along an axis for illustrating a schematic structure of a sealing structure according to an embodiment of the present invention. A sealing structure according to an embodiment of the present invention is used in a valve train of an internal combustion engine, and includes a valve stem of a valve for communicating and blocking between a cylinder and a port, and one end into which the valve stem is inserted. This seals between the valve guide facing the cam side and the other end facing the cylinder side. Hereinafter, for convenience of explanation, the reference numeral A side in the drawings is the cam side and the reference sign B side is the cylinder side. In a direction orthogonal to the axis x (hereinafter, also referred to as a radial direction), the direction toward the axis x is defined as the inner peripheral side (the direction of arrow a in FIG. 1), and the direction away from the axis x is defined as the outer peripheral side ( Direction of arrow b in FIG. 1).

  As shown in FIG. 1, the sealing structure 1 according to the present embodiment includes a valve guide 10 and a valve stem seal 20. As will be described later, the valve stem seal 20 is fitted to one end of the valve guide 10 on the cam side when the sealing structure 1 is in use. FIG. 1 shows the sealing structure 1 in a state in which the valve stem seal 20 is fitted to one end of the valve guide 10.

  The valve guide 10 has a cylindrical shape extending in the direction of the axis x, and a guide that is a through hole extending in the direction of the axis x through which the valve stem of the valve is inserted so as to be able to reciprocate in the direction of the axis x as will be described later. A hole 11 is provided. The guide hole 11 extends between an end portion 12 (one end) that is an end portion on the cam side of the valve guide 10 and an end portion 13 (the other end) that is an end portion on the cylinder side of the valve guide 10. The inner diameter of the hole 11 is larger than the outer diameter of the valve stem. Further, the valve guide 10 is an annular recess that is recessed in the direction of the cylinder-side end 13 on an end surface 12a that is a surface facing the valve stem seal 20 at the cam-side end 12 to which the valve stem seal 20 is attached. A recess 14 is provided.

  The annular recess 14 includes an annular side surface 15 that is an annular side surface extending in the direction from the end surface 12a of the end portion 12 to the end portion 13 on the cylinder side, and an end portion of the annular side surface 15 on the cylinder side (end portion 13 side). Is provided with a bottom surface 16 which is a surface extending toward the axis x. Specifically, as shown in FIG. 1, the annular side surface 15 is a cylindrical surface centered on the axis x, and the bottom surface 16 is a disk-shaped surface extending in the radial direction, and the guide hole 11. Connected to. Thus, the annular recess 14 is formed in the end 12 on the cam side of the valve guide 10 so as to cover the guide hole 11, and the guide hole 11 is formed on the bottom surface 16 of the annular recess 14 on the end 12 side. It extends to.

  The valve stem seal 20 includes an annular metal reinforcing ring 30 centered on the axis x, and an annular elastic body portion 40 centered on the axis x formed from an elastic body attached to the reinforcing ring 30. It has. The elastic body of the elastic body portion 40 is, for example, a rubber material such as fluororubber. The reinforcing ring 30 is manufactured by, for example, pressing or forging, and the elastic body portion 40 is formed by cross-linking (vulcanization) molding using a molding die. At the time of this cross-linking molding, the reinforcing ring 30 is disposed in the mold, the elastic body portion 40 is bonded to the reinforcing ring 30 by cross-linking adhesion, and the elastic body portion 40 is formed integrally with the reinforcing ring 30. The

  As shown in FIG. 1, the reinforcing ring 30 has a cylindrical shape that has a substantially L-shaped cross section (hereinafter also referred to as a cross sectional shape) along the axis x, and extends in the direction of the axis x. 31 and a hollow disk-like flange portion 32 extending from the cam-side end of the cylindrical portion 31 toward the axis x.

  The elastic body portion 40 integrally includes a seal portion 41 and a fitting portion 42. The seal portion 41 is disposed on the valve guide 10 side (cylinder side) with respect to the annular seal base portion 43 extending in the axis x direction, a seal lip 44 that abuts a valve stem that is inserted as described later, and the seal lip 44. A back pressure lip 45 that abuts against the valve stem and a valve guide abutment lip 46 that abuts against the valve guide 10 are integrally provided.

  Specifically, as shown in FIG. 1, the seal lip 44 extends from the seal base portion 43 toward the cam side, and has an annular shape centering on the axis line x at the cam side end on the inner peripheral side. A lip tip 44a is formed. The lip tip portion 44a is a wedge-shaped portion that protrudes toward the axis x and has a cross-sectional shape that is convex toward the inner peripheral side. As will be described later, in use, the seal lip 44 contacts the valve stem at the lip tip 44a.

  A garter spring 47 is fitted on the outer peripheral side of the seal lip 44 so as to face the lip tip portion 44a. The garter spring 47 urges the seal lip 44 in the direction toward the axis x, and thereby the lip tip portion. The lip tip 44a is applied with a tension force against the valve stem so that 44a follows the displacement of the valve stem.

  As shown in FIG. 1, the back pressure lip 45 is a lip extending from the cylinder side of the seal base 43 toward the axis x, and more specifically, an end 43 a that is an end of the seal base 43 on the cylinder side. It is an annular lip centering on an axis line x extending in the inner circumferential direction and in the direction toward the cylinder side from the inner circumferential side. The back pressure lip 45 enters the annular recess 14 of the valve guide 10, and at least a part thereof is accommodated in the annular recess 14. Further, as will be described later, the back pressure lip 45 abuts on the valve stem in the use state.

  As shown in FIG. 1, the valve guide contact lip 46 is a lip extending in a direction away from the axis x from the cylinder side of the seal base 43. More specifically, the valve guide abutment lip 46 is adjacent to the back pressure lip 45 on the outer peripheral side, and is centered on the axis line x extending from the outer peripheral side of the cylinder-side end portion 43 a of the seal base 43. It is a conical cylindrical protrusion. Further, the valve guide contact lip 46 extends in the outer circumferential direction and in the direction toward the cylinder side. The valve guide abutment lip 46 enters the annular recess 14 of the valve guide 10 and abuts on the annular side surface 15 of the annular recess 14.

  As described above, the back pressure lip 45 and the valve guide abutment lip 46 extend in the direction from the cylinder-side end 43a of the seal base 43 toward the cylinder, and extend in directions opposite to each other in the radial direction. . Therefore, as shown in FIG. 1, an annular groove 48 is formed between the back pressure lip 45 and the valve guide abutment lip 46, which is an annular groove that is recessed toward the cam side and opens toward the cylinder side. ing.

  As shown in FIG. 1, in the seal portion 41, the end portion (end portion 32 a) on the inner peripheral side of the flange portion 32 of the reinforcing ring 30 is positioned at the site of the seal base portion 43. That is, the back pressure lip 45 and the valve guide contact lip 46 are located on the cylinder side with respect to the flange portion 32 of the reinforcing ring 30.

  In the elastic body portion 40, the fitting portion 42 is a portion that functions because the valve stem seal 20 is fitted and fixed to the valve guide 10, and covers the cylindrical portion 31 of the reinforcing ring 30 from the inside. When the end portion 12 of the valve guide 10 is press-fitted inside the fitting portion 42 and the cylindrical portion 31, the fitting portion 42 is connected to the cylindrical portion 31 of the reinforcing ring 30 and the valve guide 10 as shown in FIG. 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 20 is fitted and fixed to the valve guide 10. The radial thickness of the fitting portion 42 is set to a predetermined thickness so that the predetermined fitting force is generated. The circumferential surface of the fitting portion 42 may be set to the predetermined thickness in a part of the range in the axis x direction, and the circumferential surface of the fitting portion 42 may be set in the entire range in the axis x direction. The predetermined thickness may be set.

  Further, as shown in FIG. 1, the elastic body portion 40 includes a cover portion 49 that covers the flange portion 32 of the reinforcing ring 30, and the cover portion 49 includes a seal portion 41, a fitting portion 42, and an elastic body portion 40. Is connected. The seal part 41, the fitting part 42, and the cover part 49 are integrally formed of the same elastic body as described above. In the present embodiment, the cover portion 49 includes a cam side cover portion 49 a that covers the cam side of the flange portion 32 and a cylinder side cover portion 49 b that covers the cylinder side of the flange portion 32. When the valve stem seal 20 is fitted to the valve guide 10, the cylinder-side cover portion 49 b comes into contact with the end surface 12 a of the valve guide 10 so that the cylinder-side cover portion 49 b faces the cylinder side. The thickness in the direction of the axis x may be set at least in part so that the valve stem seal 20 is positioned.

  Next, the operation of the sealing structure 1 having the above-described configuration will be described. The sealing structure 1 is used in the valve train of the internal combustion engine as described above. FIG. 2 is a cross-sectional view along the axis x of the sealing structure 1 according to the embodiment of the present invention in a state where it is used in an internal combustion engine.

  As shown in FIG. 2, when the sealing structure 1 is in use, the valve stem 60 of the valve is inserted into the guide hole 11 of the valve guide 10 from the cylinder side and is inserted into the valve stem seal 20. The valve stem 60 is driven to reciprocate in the direction of the axis x by a cam (not shown). In the valve stem seal 20, the lip tip portion 44 a of the seal lip 44 abuts the outer peripheral surface 61, which is the outer peripheral surface of the valve stem 60, so that the valve stem 60 is slidable. The valve stem 60 is slidably in contact with the outer peripheral surface 61 of the valve stem 60. An annular space g is formed between the guide hole 11 of the valve guide 10 and the outer peripheral surface 61 of the valve stem 60 so that the valve stem 60 can slide in the guide hole 11 of the valve guide 10. It has become.

  The seal lip 44 of the valve stem seal 20 has a lip tip 44a abutting against the outer peripheral surface 61 of the valve stem 60 to seal the space g from the cam side to which the lubricating oil is supplied. A predetermined amount of lubricating oil leaks from the lip tip 44a, and the leaked lubricating oil is supplied to the space g. The predetermined amount of lubricating oil leaking from the lip tip 44a is such that the oil film is formed in the space g and the valve stem 60 can slide smoothly with respect to the guide hole 11 of the valve guide 10. It is. The seal lip 44 has an amount of leakage adjusted so that such an appropriate amount of lubricating oil leaks from between the lip tip 44a and the outer peripheral surface 61 of the valve stem 60 and is supplied to the space g.

  Further, the back pressure lip 45 is in contact with the outer peripheral surface 61 of the valve stem 60 at the inner peripheral side portion, and the back pressure from the cylinder side is prevented from being applied to the seal lip 44. As a result, the seal lip 44 is prevented from being deformed by receiving back pressure, and the supply amount (leakage amount) of the lubricating oil by the seal lip 44 is stabilized.

  Further, the valve guide contact lip 46 is in contact with the annular side surface 15 of the annular recess 14 of the valve guide 10 at the outer peripheral portion. For this reason, only the back pressure lip 45 and the valve guide abutment lip 46 receive the back pressure in the space formed by the annular recess 14 in the valve stem seal 20, and the cylinder side of the elastic body portion 40 as in the prior art. No back pressure is applied to the cover portion 49b. For this reason, the pressure receiving area where the valve stem seal 20 receives the back pressure can be reduced, and the force that the valve stem seal 20 receives by the back pressure in the cam side direction can be reduced. Thereby, the omission of the valve stem seal 20 from the valve guide 10 due to the back pressure can be suppressed.

  Further, since the valve guide contact lip 46 is in contact with the annular side surface 15 of the annular recess 14 of the valve guide 10 at the outer peripheral portion, the reaction force to the valve guide contact lip 46 due to the contact is the inner periphery. Head to the side. As described above, the reaction force caused by the contact of the valve guide contact lip 46 does not occur in the direction of the axis x that urges the valve stem seal 20 in the direction of pulling out the valve guide 10. For this reason, the valve guide abutment lip 46 can reduce the pressure receiving area of the back pressure without generating a force for urging the valve stem seal 20 in the direction of removing the valve stem seal 20 from the valve guide 10.

  As shown in FIG. 2, an annular groove 48, which is an annular groove opened to the space formed by the annular recess 14, is formed between the back pressure lip 45 and the valve guide contact lip 46. . For this reason, when back pressure is applied to the back pressure lip 45 and the valve guide abutment lip 46, the back pressure urges the back pressure lip 45 toward the abutting valve stem 60 in the annular groove 48, and the valve guide abutment. The contact lip 46 is urged toward the annular side surface 15 of the annular recess 14 of the valve guide 10 in contact therewith. For this reason, in the state where back pressure is applied, the force with which the back pressure lip 45 abuts on the valve stem 60 and the force with which the valve guide abutment lip 46 abuts on the annular side surface 15 of the annular recess 14 of the valve guide 10 are increased. Can be made. As a result, it is possible to further suppress the back pressure from passing between the back pressure lip 45 and the valve stem 60, and to further stabilize the supply amount of the lubricating oil by the seal lip 44. Further, it is possible to suppress the back pressure from passing between the valve guide abutment lip 46 and the annular side surface 15 of the annular recess 14, and further prevent the valve stem seal 20 from coming off from the valve guide 10. Can do.

  As shown in FIGS. 1 and 2, the shape of the annular groove 48 is preferably a shape in which the width in the radial direction becomes narrower toward the cam side. The side surfaces (side surfaces 48a and 48b) of the annular groove 48 may be linear inclined surfaces or curved inclined surfaces.

  Thus, according to the sealing structure 1 according to the embodiment of the present invention, the fitting of the valve stem seal 20 to the valve guide 10 via the elastic body is maintained, while the valve guide 10 of the valve stem seal 20 is maintained. Omission can be suppressed.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the sealing structure 1 according to the above-described embodiment, and all aspects included in the concept of the present invention and the claims. including. In addition, the configurations may be appropriately combined as appropriate so as to achieve at least part of the problems and effects described above. For example, the shape, material, arrangement, size, and the like of each component in the above embodiment can be appropriately changed according to the specific usage mode of the present invention.

DESCRIPTION OF SYMBOLS 1 Sealing structure 10,111 Valve guide 11 Guide hole 12,13 End part 12a End surface 14 Annular recessed part 15 Annular side face 16 Bottom face 20,100 Valve stem seal 30,101 Reinforcement ring 31 Cylindrical part 32 Flange part 32a End part 40,102 Elasticity Body part 41 Seal part 42, 105 Fitting part 43 Seal base part 43a End part 44, 103 Seal lip 44a Lip tip part 45, 104 Back pressure lip 46 Valve guide contact lip 47 Garter spring 48 Annular groove 48a, 48b Side face 49 Cover Part 49a cam side cover part 49b cylinder side cover part 60, 110 valve stem 61 outer peripheral surface g space x axis

Claims (5)

Sealing between a valve stem of a valve for communicating and blocking between a cylinder and a port in an internal combustion engine, and a valve guide having one end through which the valve stem is inserted facing the cam side and the other end facing the cylinder side A sealing structure for achieving
A valve guide,
A valve stem seal fitted to the valve guide at one end of the valve guide;
The valve stem seal includes an annular reinforcing ring centered on an axis, and an annular elastic body portion centered on the axis formed from an elastic body attached to the reinforcing ring,
The elastic body portion includes a seal lip that abuts on the valve stem, a back pressure lip that abuts on the valve stem disposed on the valve guide side from the seal lip, and a valve guide abutment lip that abuts on the valve guide A sealing portion, and a fitting portion pressed between the reinforcing ring and the valve guide,
The valve guide includes, at the one end, an annular annular recess that is recessed in the other end direction to form an annular side surface extending from the one end in the other end direction,
The back pressure lip is at least partially housed in the annular recess,
The sealing structure according to claim 1, wherein the valve guide contact lip contacts the annular side surface of the annular recess.   2. The sealing structure according to claim 1, wherein an annular groove that opens toward the other end of the valve guide is formed between the back pressure lip and the valve guide contact lip.   The sealing structure according to claim 2, wherein the annular groove has a shape in which a width in a direction perpendicular to the axis is narrowed toward the cam side.   The seal portion includes an annular seal base, the seal lip extends from the seal base to the cam side, and the back pressure lip extends from the valve guide side of the seal base toward the axis. 4. The valve guide abutting lip extends from the valve guide side of the seal base toward the annular side surface of the annular recess. Sealing structure.   The reinforcing ring includes a cylindrical cylindrical portion extending in the axial direction, and a hollow disk-shaped flange portion extending from one end of the cylindrical portion toward the axial line, and an end of the flange portion on the axial side is provided. The sealing structure according to claim 4, wherein the sealing portion is located at a position of the seal base portion.

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