JP2021021418A - Sealing structure - Google Patents

Abstract

To provide a sealing device in which a flange for supporting a spring force has high durability.SOLUTION: A sealing structure has a cylindrical guide 18 for reciprocally guiding a rod body 14 in an axial line direction, a support body 2 attached with the guide, a sealing device 30 for covering an end part of the guide, and a compression coil spring 29 for pressing the sealing device to the support body. The sealing device has an elastic ring 34 and a stiff ring 36. The elastic ring has lips 44. 46 with which an external peripheral face of the rod body slidably contacts. The stiff ring has a cylinder part 54 and a flange 58. The flange has a first face 60 which is inclined so as to separate from a plane orthogonal to an axial line of the cylinder part including the end part of the cylinder part as progressing toward the outside in a radial direction, and contacting with the support body, and a second face 62 located at a side opposite to the first face, and pressed by the compression coil spring. The compression coil spring is arranged at a periphery of the cylinder part, and a seat winding of an end part of the compression coil spring at the flange side has an inclination plane which surface-contacts with the second face.SELECTED DRAWING: Figure 2

Description

The present invention relates to a sealing structure having a sealing device such as a valve stem seal.

Intake valves and exhaust valves are arranged at the intake and exhaust ports of internal combustion engines such as gasoline engines and diesel engines used in automobiles, ships, agricultural machinery, and the like, respectively. Each valve has a valve stem and a valve stem guide that reciprocates the valve stem in the axial direction. A valve stem seal is used to limit the entry of engine oil into the gap between the valve stem and the valve stem guide. The valve stem seal allows the surrounding engine oil to flow into the gap between the valve stem and the valve stem guide and lubricates the valve stem and valve stem guide. However, in order to reduce or prevent the generation of white smoke due to engine oil and reduce the consumption of engine oil, the valve stem seal appropriately suppresses the inflow of engine oil into the gap between the valve stem and the valve stem guide. To do.

It is known that the valve stem seal is subjected to high pressure in the combustion chamber of the internal combustion engine through the above gap. In particular, the valve stem seal provided in the exhaust port is subjected to high pressure in the exhaust process.

Patent Document 1 discloses a valve stem seal including a portion formed of an elastic body and a metal ring. The flange formed at one end of the metal ring functions as a spring retainer portion. The end of the coil spring that applies force to the valve stem is brought into contact with the spring retainer portion in the direction in which the valve stem is always lifted. Since a reaction force is applied to the spring retainer portion from the coil spring, it is considered that the valve stem seal is prevented from coming off from the valve stem guide even when the above high pressure is applied.

JP-A-2009-257401

It is desirable that the above flange supporting the force of the spring has high durability.

Therefore, the present invention provides a sealing structure in which the flange supporting the force of the spring has high durability.

The sealing structure according to an aspect of the present invention includes a cylindrical guide that reciprocates a rod having a cylindrical portion in the axial direction of the rod, a support to which the guide is attached, and a guide of the guide. It has a sealing device that covers the ends and a compression coil spring that presses the sealing device against the support. The sealing device has an elastic ring formed of an elastic material and a rigid ring formed of a rigid material fixed to the elastic ring so as to reinforce the elastic ring. The elastic ring has a lip that slidably contacts the outer peripheral surface of the rod body. The rigid ring has a cylindrical portion arranged radially outward of the end of the guide and a flange extending radially outward from the end of the cylindrical portion opposite to the lip. The flange is inclined so as to be far outside in the radial direction from a plane orthogonal to the axis of the cylindrical portion including the end portion of the cylindrical portion, and has a first surface in contact with the support and the first surface. It has a second surface that is on the opposite side of the surface and is pressed by the compression coil spring. The compression coil spring is arranged around the cylindrical portion, and has an inclined plane in which the end turn of the end portion of the compression coil spring on the flange side contacts the second surface.

In this embodiment, the flange can be used as a spring retainer or spring seat to support the force of the compression coil spring. The flange is inclined toward the outer side in the radial direction so as to be away from a plane orthogonal to the axis of the cylindrical portion including the end portion of the cylindrical portion. The end turn on the flange side of the compression coil spring has an inclined plane that makes surface contact with the second surface of the flange. Therefore, the first surface of the flange is in contact with the support, and the second surface of the flange is in surface contact with the inclined plane of the end turn on the flange side of the compression coil spring. In this way, the flange is firmly sandwiched between the support and the end turn of the compression coil spring, and the second surface of the flange comes into surface contact with the inclined plane of the end turn of the compression coil spring over a wide area. Deformation is suppressed and the durability of the flange is improved.

Preferably, the support has an inclined support surface that contacts the first surface of the flange.

In this case, the first surface of the flange comes into surface contact with the inclined support surface of the support, and the second surface of the flange comes into surface contact with the inclined plane of the end turn of the compression coil spring. As described above, when both sides of the flange are firmly in surface contact with the support and the end turn of the compression coil spring, the deformation of the flange is suppressed and the durability of the flange is further improved.

The sealing structure according to another aspect of the present invention includes a cylindrical guide that reciprocates a rod body having a cylindrical portion in the axial direction of the rod body, a support to which the guide is attached, and the guide. It has a sealing device that covers the end of the sealing device and a compression coil spring that presses the sealing device against the support. The sealing device has an elastic ring formed of an elastic material and a rigid ring formed of a rigid material fixed to the elastic ring so as to reinforce the elastic ring. The elastic ring has a lip that slidably contacts the outer peripheral surface of the rod body. The rigid ring has a cylindrical portion arranged radially outward of the end of the guide and a flange extending radially outward from the end of the cylindrical portion opposite to the lip. The flange is inclined so as to be far outside in the radial direction from a plane orthogonal to the axis of the cylindrical portion including the end portion of the cylindrical portion, and has a first surface in contact with the support and the first surface. It has a second surface that is on the opposite side of the surface and is pressed by the compression coil spring. The compression coil spring is arranged around the cylindrical portion. The support has an inclined support surface that contacts the first surface of the flange.

In this embodiment, the flange can be used as a spring retainer or spring seat to support the force of the compression coil spring. The flange is inclined toward the outer side in the radial direction so as to be away from a plane orthogonal to the axis of the cylindrical portion including the end portion of the cylindrical portion. The second surface of the flange is in contact with the compression coil spring and the first surface of the flange is in surface contact with the inclined support surface of the support. In this way, the flange is firmly sandwiched between the support and the compression coil spring, and the first surface of the flange comes into surface contact with the inclined support surface of the support over a wide area, so that the deformation of the flange is suppressed. The durability of the flange is improved.

It is sectional drawing of a part of the internal combustion engine which uses the sealed structure which concerns on embodiment of this invention. It is a partial cross-sectional view which shows the sealed structure which concerns on embodiment. It is a perspective view which shows by breaking a part of the sealing structure which concerns on embodiment. It is a perspective view which shows by breaking a part of the sealing structure which concerns on a comparative example. It is a partial cross-sectional view which shows the sealing structure which concerns on the modification of embodiment.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. Drawing scales are not always accurate and some features may be exaggerated or omitted.

As shown in FIG. 1, the internal combustion engine 1 in which the sealed structure according to the embodiment is used includes a cylinder head 2. The cylinder head 2 is arranged above the cylinder (not shown). A piston (not shown) is arranged inside the cylinder so that it can reciprocate. The cylinder head 2, the cylinder and the piston define the combustion chamber 4. An intake port 6 and an exhaust port 8 are formed in the cylinder head 2, and an intake valve 10 and an exhaust valve 12 are arranged in the intake port 6 and the exhaust port 8, respectively.

Each of the intake valve 10 and the exhaust valve 12 has a cylindrical valve stem (rod body) 14 and a valve head 16 attached to the lower end of the valve stem 14. Each valve can reciprocate in the axial direction of the valve stem 14, and the valve head 16 opens and closes the port 6 or 8 with the reciprocating motion. A cylindrical valve stem guide (guide) 18 for guiding the reciprocating motion of each valve stem 14 is fixed to the cylinder head 2, and the valve stem 14 is inserted into the valve stem guide 18.

A cam follower 20 is attached to the upper end of each valve stem 14. The cam 24 attached to the cam shaft 22 comes into contact with the upper surface of the cam follower 20.

A spring seat 26 is attached to the upper end of each valve stem 14. A coil spring 29 is arranged in a compressed state between the spring seat 26 and the spring seat 28 formed on the cylinder head 2. The elastic restoring force of the compression coil spring 29 acts in the direction of constantly lifting the valve stem 14 upward.

In the above configuration, when the cam 24 pushes down the cam follower 20 against the elastic restoring force of the compression coil spring 29 due to the rotation of the cam shaft 22, the valve stem 14 is lowered and the port 6 or 8 is opened. When the rotation of the camshaft 22 reduces the force with which the cam 24 pushes down the cam follower 20, the elastic restoring force of the compression coil spring 29 raises the valve stem 14 and closes the port 6 or 8.

The end portion of the valve stem guide 18 and the central portion of the valve stem 14 are covered with the valve stem seal (sealing device) 30. The valve stem seal 30 allows the engine oil in the surrounding oil chamber 32 to flow into the gap between the valve stem 14 and the valve stem guide 18 (gap Ga in FIG. 2), and allows the valve stem 14 and the valve stem guide 18 to flow. Lubricate. However, in order to reduce or prevent the generation of white smoke due to the engine oil and reduce the consumption of the engine oil, the valve stem seal 30 reduces the amount of engine oil flowing into the gap between the valve stem 14 and the valve stem guide 18. Appropriately suppress.

A sealing structure having a valve stem seal 30 and a valve stem guide 18 will be described in more detail with reference to FIG. FIG. 2 shows the valve stem seal 30 in use, which is in contact with the valve stem 14 and the valve stem guide 18. The valve stem seal 30 and the valve stem guide 18 have a cylindrical shape, but only the left side portion thereof is shown in FIG.

The inner peripheral surface of the valve stem guide 18 is arranged with a gap Ga from the outer peripheral surface of the valve stem 14. The valve stem seal 30 is given a high pressure (hereinafter, referred to as “back pressure”) of the combustion chamber 4 through the gap Ga. In particular, the valve stem seal 30 provided in the exhaust port 8 is given a high back pressure in the exhaust process.

The valve stem seal 30 has a double structure having an elastic ring 34 and a rigid ring 36. The elastic ring 34 is formed of an elastic material (for example, an elastomer). The rigid ring 36 is formed of a rigid material (for example, metal) and is brought into close contact with the elastic ring 34 to reinforce the elastic ring 34.

The elastic ring 34 includes an elastic ring cylindrical portion 38, an inner annular portion 40, and a connecting annular portion 42. The elastic ring cylindrical portion 38 is arranged on the radial outer side of the end portion of the valve stem guide 18, and the valve stem guide 18 is fitted into the elastic ring cylindrical portion 38 by a tightening method. Therefore, the inner peripheral surface of the elastic ring cylindrical portion 38 comes into surface contact with the outer peripheral surface of the valve stem guide 18. The inner annular portion 40 is arranged above the elastic ring cylindrical portion 38 and has an outer diameter and an inner diameter smaller than those of the elastic ring cylindrical portion 38. The connecting annular portion 42 connects the upper end of the elastic ring cylindrical portion 38 and the inner annular portion 40.

A main lip 44, a back pressure lip 46, and a plurality of protrusions 48 are formed on the inner ring portion 40. The outer peripheral surface of the valve stem 14 slidably contacts the main lip 44 and the back pressure lip 46. The main lip 44 is mainly provided so that the engine oil in the oil chamber 32 does not excessively flow toward the valve stem guide 18. The back pressure lip 46 receives the back pressure applied to the valve stem seal 30 through the gap Ga between the valve stem 14 and the valve stem guide 18. The back pressure lip 46 is provided so that the main lip 44 is not excessively deformed due to excessive back pressure. The plurality of protrusions 48 are intermittently arranged in the circumferential direction so as to surround the valve stem 14. When the valve stem seal 30 is attached to the valve stem guide 18, these protrusions 48 have the main lip 44 and the back pressure lip 46 of the valve stem 14 even if the valve stem seal 30 is eccentric with respect to the valve stem 14. It is provided so that the contact pressure is almost uniform over the entire circumference.

As shown in FIG. 2, when the valve stem 14 is contacted, the main lip 44 and the back pressure lip 46 are deformed and come into contact with the outer peripheral surface of the valve stem 14 over the entire circumference. However, in order to supply an appropriate amount of engine oil to the gap Ga between the valve stem 14 and the valve stem guide 18, a minute gap (not shown) is provided between the main lip 44 and the outer peripheral surface of the valve stem 14. A minute gap (not shown) is also provided between the back pressure lip 46 and the outer peripheral surface of the valve stem 14.

Although not essential, a garter spring 50 may be wound around the inner annulus 40. In this embodiment, a peripheral groove 52 for receiving the garter spring 50 is formed on the outer peripheral surface of the inner ring portion 40. The garter spring 50 presses the main lip 44 and the protrusion 48 inward to increase the contact pressure between the main lip 44 and the protrusion 48 with respect to the valve stem 14.

The rigid ring 36 includes a rigid ring cylindrical portion 54, an annular portion 56, and a flange 58. The rigid ring cylindrical portion 54 is arranged on the radial outer side of the elastic ring cylindrical portion 38 of the elastic ring 34, and is fixed to the outer peripheral surface of the elastic ring cylindrical portion 38. Therefore, the elastic ring cylindrical portion 38 of the elastic ring 34 is surrounded by the rigid ring cylindrical portion 54 of the rigid ring 36 over the entire circumference, and the movement or expansion in the radial direction is restricted.

The annular portion 56 extends radially inward from the end of the rigid ring cylindrical portion 54 on the side of the main lip 44. The annular portion 56 is fixed to the inner annular portion 40 and the connecting annular portion 42 of the elastic ring 34.

The flange 58 is an annular plate extending radially outward from the opposite end of the main lip 44 of the rigid ring cylindrical portion 54. The flange 58 is used as a spring retainer or a spring seat to which the lower end portion of the compression coil spring 29 is brought into contact. Therefore, the compression coil spring 29 arranged around the rigid ring cylindrical portion 54 presses the flange 58 of the valve stem seal 30 against the cylinder head 2.

The flange 58 is inclined so as to be farther outward in the radial direction from a virtual plane F orthogonal to the axis of the rigid ring cylindrical portion 54 including the end portion of the rigid ring cylindrical portion 54.

The flange 58 has a first surface 60 and a second surface 62. The first surface 60 is on the side opposite to the main lip 44 in the axial direction of the valve stem guide 18, and comes into contact with the support surface 28A of the spring seat 28 of the cylinder head 2. The second surface 62 is on the side of the main lip 44 in the axial direction of the valve stem guide 18, comes into contact with the compression coil spring 29, and is pressed by the compression coil spring 29. The flange 58 is inclined, the first surface 60 has a truncated cone shape having a truncated cone that intersects the virtual plane F at an inclination angle θ, and the second surface 62 is also virtual. It has a truncated cone shape with a matrix surface that intersects the plane F at an inclination angle θ. In an embodiment, the second surface 62 is parallel to the first surface 60, but is not necessarily parallel.

The end turn 29A of the lower end portion (end portion on the flange 58 side) of the compression coil spring 29 is brought into surface contact with the second surface 62 of the flange 58. Therefore, the end turn 29A has an inclined flat surface 29B that comes into surface contact with the second surface 62 of the flange 58. The inclined plane 29B is also inclined so as to be farther outward in the radial direction from a virtual plane F orthogonal to the axis of the rigid ring cylindrical portion 54 including the end portion of the rigid ring cylindrical portion 54. That is, the inclined plane 29B also has a truncated cone shape having a mother plane intersecting the virtual plane F at an inclination angle θ.

Therefore, the first surface 60 of the flange 58 comes into contact with the cylinder head 2, and the second surface 62 of the flange 58 comes into surface contact with the inclined flat surface 29B of the end turn 29A on the flange 58 side of the compression coil spring 29. In this way, the flange 58 is firmly sandwiched between the cylinder head 2 and the end turn 29A of the compression coil spring 29, and the second surface 62 of the flange 58 has a large area on the inclined flat surface 29B of the end turn 29A of the compression coil spring 29. The surface contact with the flange 58 suppresses the deformation of the flange 58 and improves the durability of the flange 58.

Although not shown, a rotation stopper (for example, a protrusion) may be formed on the second surface 62 to prevent the compression coil spring 29 from rotating about its axis.

A reaction force is always applied to the flange 58 from the compression coil spring 29, so that the entire valve stem seal 30 is always pressed downward. Therefore, even if a high back pressure is applied to the valve stem seal 30 through the gap Ga between the valve stem 14 and the valve stem guide 18, the valve stem seal 30 is unlikely to come off from the valve stem guide 18. In this way, the flange 58 functions as a spring retainer or a spring seat, and at the same time, functions as a stopper for the valve stem seal 30.

The cylinder head 28 has an inclined support surface 28A that makes surface contact with the first surface 60 of the flange 58. That is, the support surface 28A also has a truncated cone shape having a mother surface that intersects the virtual plane F at an inclination angle θ. Therefore, the first surface 60 of the flange 58 is in surface contact with the inclined support surface 28A of the cylinder head 2 over a wide area, and the second surface 62 of the flange 58 is on the inclined plane 29B of the end turn 29A of the compression coil spring 29. Face contact. In this way, both sides of the flange 58 are firmly in surface contact with the cylinder head 2 and the end turn 29A of the compression coil spring 29, so that the deformation of the flange 58 is suppressed and the durability of the flange 58 is further improved.

FIG. 3 is a perspective view showing a part of the sealed structure according to the embodiment broken, and FIG. 4 is a perspective view showing a part of the sealed structure according to the comparative example broken.

In the comparative example, the end turn 29A of the lower end portion (the end portion on the flange 58 side) of the compression coil spring 29 has a flat surface 29C, and the flat surface 29C is a plane orthogonal to the axis of the rigid ring cylindrical portion 54. Therefore, a gap g is formed between the second surface 62 of the flange 58 and the flat surface 29C. Therefore, as the compression coil spring 29 expands and contracts, repeated stress is applied to the flange 58, and the flange 58 is repeatedly deformed.

On the other hand, in the embodiment, the inclined second surface 62 of the flange 58 comes into surface contact with the inclined plane 29B of the end turn 29A of the compression coil spring 29 over a wide area, so that the deformation of the flange 58 is suppressed. .. More preferably, the inclined first surface 60 of the flange 58 comes into surface contact with the inclined support surface 28A of the cylinder head 2 over a wide area, so that the deformation of the flange 58 is further suppressed.

Although the present invention has been illustrated and described with reference to the preferred embodiments of the present invention, those skilled in the art can change the form and details without departing from the scope of the invention described in the claims. It will be understood that there is. Such changes, modifications and modifications should be within the scope of the present invention.

For example, in the above embodiment, the end turn 29A of the compression coil spring 29 has an inclined plane 29B in surface contact with the second surface 62 of the flange 58, and the cylinder head 28 is on the first surface 60 of the flange 58. It has an inclined support surface 28A that makes surface contact. However, the cylinder head 28 may have an inclined plane 29B, and the plane 29B of the end turn 29A may be orthogonal to the axis of the rigid ring cylindrical portion 54 without being inclined. On the contrary, the end turn 29A may have an inclined plane 29B, and the plane 29B may be orthogonal to the axis of the rigid ring cylindrical portion 54 without being inclined.

In the above embodiment, the rigid ring cylindrical portion 54 of the rigid ring 36 does not come into direct contact with the valve stem guide 18, and the valve stem guide 18 is fitted into the elastic ring cylindrical portion 38 of the elastic ring 34 to form a rigid ring. The cylindrical portion 54 restrains the elastic ring cylindrical portion 38. However, as shown in FIG. 5, in the valve stem seal 30 having the short elastic ring cylindrical portion 38, the valve stem guide 18 may be fitted into the rigid ring cylindrical portion 54.

In the above embodiment, the sealing device is a valve stem seal 30 that seals the valve stem 14 and the valve stem guide 18. However, the present invention can also be applied to a sealing device that seals a piston (reciprocating rod) of a piston type fuel pump and a piston guide.

The inner peripheral surface of the elastic ring cylindrical portion 38 of the elastic ring 34 may be coated with a resin material having a small friction coefficient and harder than the elastomer so that the valve stem guide 18 can be easily fitted into the elastic ring cylindrical portion 38. Examples of such resin materials include polyetheretherketone (PEEK), polyphenylene sulfide (PPS), and polytetrafluoroethylene (PTFE).

At least one of the main lip 44, the back pressure lip 46 and the protrusion 48 of the elastic ring 34 may be coated with such a resin material to reduce their wear.

In the above embodiment, the compression coil spring 29 has a cylindrical shape having a uniform coil diameter. However, coil springs having other shapes such as conical coil springs and barrel coil springs having different coil diameters in the axial direction may be used.

2 Cylinder head (support)
14 Valve stem (bar)
18 Valve stem guide (guide)
28 Spring seat (support plane)
28A Support surface 29A End roll 29B Inclined plane 30 Valve stem seal (sealing device)
32 Oil chamber 34 Elastic ring 36 Rigid ring 44 Main lip 46 Back pressure lip 54 Rigid ring Cylindrical part 58 Flange 60 First surface 62 Second surface

Claims (3)

A cylindrical guide that reciprocates a rod body having a cylindrical portion in the axial direction of the rod body, and a cylindrical guide.
The support to which the guide is attached and
A sealing device that covers the end of the guide and
It has a compression coil spring that presses the sealing device against the support.
The sealing device has an elastic ring formed of an elastic material and a rigid ring formed of a rigid material fixed to the elastic ring so as to reinforce the elastic ring.
The elastic ring has a lip that slidably contacts the outer peripheral surface of the rod body.
The rigid ring has a cylindrical portion arranged radially outside the end of the guide and a flange extending radially outward from the end of the cylinder opposite the lip.
The flange is inclined so as to be far outside in the radial direction from a plane orthogonal to the axis of the cylindrical portion including the end portion of the cylindrical portion, and has a first surface in contact with the support and the first surface. It has a second surface that is on the opposite side of the surface and is pressed by the compression coil spring.
The compression coil spring is arranged around the cylindrical portion, and is characterized in that the end turn of the end portion of the compression coil spring on the flange side has an inclined plane that makes surface contact with the second surface. Sealed structure. The sealing structure according to claim 1, wherein the support has an inclined support surface that comes into surface contact with the first surface of the flange. A cylindrical guide that reciprocates a rod body having a cylindrical portion in the axial direction of the rod body, and a cylindrical guide.
The support to which the guide is attached and
A sealing device that covers the end of the guide and
It has a compression coil spring that presses the sealing device against the support.
The sealing device has an elastic ring formed of an elastic material and a rigid ring formed of a rigid material fixed to the elastic ring so as to reinforce the elastic ring.
The elastic ring has a lip that slidably contacts the outer peripheral surface of the rod body.
The rigid ring has a cylindrical portion arranged radially outside the end of the guide and a flange extending radially outward from the end of the cylinder opposite the lip.
The flange is inclined so as to be far outside in the radial direction from a plane orthogonal to the axis of the cylindrical portion including the end portion of the cylindrical portion, and has a first surface in contact with the support and the first surface. It has a second surface that is on the opposite side of the surface and is pressed by the compression coil spring.
The compression coil spring is arranged around the cylindrical portion, and the compression coil spring is arranged around the cylindrical portion.
The support has a sealed structure characterized by having an inclined support surface that comes into surface contact with the first surface of the flange.

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