JP7344696B2 - Sealed structure - Google Patents

Description

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

BACKGROUND ART Intake valves and exhaust valves are respectively arranged at the intake ports and exhaust ports of internal combustion engines such as gasoline engines and diesel engines used in automobiles, ships, agricultural machinery, and the like. Each valve has a valve stem and a valve stem guide that guides the valve stem in an axially reciprocating manner. Valve stem seals are used to limit the ingress of engine oil into the gap between the valve stem and the valve stem guide. The valve stem seal allows ambient engine oil to flow into the gap between the valve stem and valve stem guide, lubricating the valve stem and valve stem guide. However, in order to reduce or prevent the generation of white smoke caused by engine oil and reduce engine oil consumption, the valve stem seal appropriately suppresses the amount of engine oil flowing into the gap between the valve stem and the valve stem guide. do.

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

Patent Document 1 discloses a valve stem seal that includes a portion made of an elastic body and a metal ring. A flange formed at one end of the metal ring functions as a spring retainer. An end of a coil spring that applies force to the valve stem in a direction that constantly lifts the valve stem is brought into contact with the spring retainer. Since a reaction force is applied to the spring retainer part from the coil spring, it is thought that even if the above-mentioned high pressure is applied, the valve stem seal is prevented from coming off from the valve stem guide.

Japanese Patent Application Publication No. 2009-257401

It is desirable that the above-mentioned flange, which supports 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.

A sealing structure according to an aspect of the present invention includes: a cylindrical guide that guides a rod having a cylindrical portion in a reciprocating manner in the axial direction of the rod; a support to which the guide is attached; It has a sealing device covering the end and a compression coil spring pressing the sealing device against the support. The sealing device has an elastic ring made of an elastic material and a rigid ring made of a rigid material fixed to the elastic ring to reinforce the elastic ring. The elastic ring has a lip with which the outer peripheral surface of the rod comes into slidable contact. The rigid ring has a cylindrical portion disposed radially outward from 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 that the radially outer side is further away from a plane perpendicular to the axis of the cylindrical portion including the end of the cylindrical portion, and has a first surface that contacts the support body, and a first surface that contacts the support body; It has a second surface opposite to the surface and pressed by the compression coil spring. The compression coil spring is disposed around the cylindrical portion, and has an inclined plane in which an end turn of the flange side end of the compression coil spring is in surface contact with 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 so that the radially outer side thereof is further away from a plane perpendicular 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 in surface contact with the second surface of the flange. Thus, the first surface of the flange contacts the support and the second surface of the flange makes 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 tightly sandwiched between the support and the end turn of the compression coil spring, and the second surface of the flange is in surface contact with the inclined plane of the end turn of the compression coil spring over a large area, so that the flange Deformation is suppressed and the durability of the flange is improved.

Preferably, the support has an inclined support surface in surface contact with the first surface of the flange.

In this case, the first surface of the flange is in surface contact with the inclined support surface of the support, and the second surface of the flange is in surface contact with the inclined plane of the end turn of the compression coil spring. In this way, both sides of the flange are firmly in surface contact with the support and the end turn of the compression coil spring, thereby suppressing deformation of the flange and further improving the durability of the flange.

A sealing structure according to another aspect of the present invention includes: a cylindrical guide that guides a rod having a cylindrical portion in a reciprocating manner in the axial direction of the rod; a support to which the guide is attached; and a support body to which the guide is attached. and a compression coil spring for pressing the seal against the support. The sealing device has an elastic ring made of an elastic material and a rigid ring made of a rigid material fixed to the elastic ring to reinforce the elastic ring. The elastic ring has a lip with which the outer peripheral surface of the rod comes into slidable contact. The rigid ring has a cylindrical portion disposed radially outward from 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 that the radially outer side is further away from a plane perpendicular to the axis of the cylindrical portion including the end of the cylindrical portion, and has a first surface that contacts the support body, and a first surface that contacts the support body; It has a second surface opposite to the surface and pressed by the compression coil spring. The compression coil spring is arranged around the cylindrical portion. The support has an inclined support surface in surface contact with 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 so that the radially outer side thereof is further away from a plane perpendicular to the axis of the cylindrical portion including the end portion of the cylindrical portion. The second side of the flange contacts the compression coil spring, and the first side of the flange makes surface contact with the sloped 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 makes surface contact over a wide area with the inclined support surface of the support, thereby suppressing deformation of the flange. The durability of the flange is improved.

1 is a cross-sectional view of a portion of an internal combustion engine in which a sealing structure according to an embodiment of the present invention is used. FIG. 2 is a partial cross-sectional view showing a sealing structure according to an embodiment. FIG. 2 is a partially cutaway perspective view of the sealing structure according to the embodiment. FIG. 3 is a partially cutaway perspective view of a sealing structure according to a comparative example. FIG. 7 is a partial cross-sectional view showing a sealing structure according to a modification of the embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are not necessarily to scale and some features may be exaggerated or omitted.

As shown in FIG. 1, an internal combustion engine 1 in which the sealing structure according to the embodiment is used includes a cylinder head 2. As shown in FIG. The cylinder head 2 is arranged above a cylinder (not shown). A piston (not shown) is disposed inside the cylinder so as to be able to reciprocate. The cylinder head 2, cylinder and piston define a 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) 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 as the valve stem 14 reciprocates. A cylindrical valve stem guide (guide) 18 that guides the reciprocating movement 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. A cam 24 attached to a camshaft 22 contacts the upper surface of the cam follower 20.

Further, 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 a spring seat 28 formed in the cylinder head 2. The elastic restoring force of the compression coil spring 29 always acts in a direction to lift 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 camshaft 22, the valve stem 14 descends and the port 6 or 8 is opened. When the force with which the cam 24 pushes down the cam follower 20 decreases due to the rotation of the camshaft 22, the elastic restoring force of the compression coil spring 29 causes the valve stem 14 to rise and the port 6 or 8 to be closed.

The ends of the valve stem guide 18 and the center of the valve stem 14 are covered with a 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 (the gap Ga in FIG. 2), and Lubricate. However, in order to reduce or prevent the generation of white smoke due to engine oil and reduce engine oil consumption, 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. Suppress appropriately.

Referring to FIG. 2, the sealing structure having the valve stem seal 30 and the valve stem guide 18 will be described in more detail. FIG. 2 shows the valve stem seal 30 in use and in contact with the valve stem 14 and valve stem guide 18. Although the valve stem seal 30 and the valve stem guide 18 have a cylindrical shape, only their left side portions are shown in FIG.

The inner circumferential surface of the valve stem guide 18 is spaced apart from the outer circumferential surface of the valve stem 14 with a gap Ga therebetween. The high pressure of the combustion chamber 4 (hereinafter referred to as "back pressure") is applied to the valve stem seal 30 through the gap Ga. In particular, the valve stem seal 30 provided at the exhaust port 8 is subjected to high back pressure during 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 from an elastic material (eg, an elastomer). Rigid ring 36 is formed from a rigid material (eg, metal) and is brought into close contact with elastic ring 34 to reinforce elastic ring 34 .

The elastic ring 34 includes an elastic ring cylindrical section 38 , an inner annular section 40 , and a connecting annular section 42 . The elastic ring cylindrical portion 38 is disposed radially outward of the end of the valve stem guide 18, and the valve stem guide 18 is fitted into the elastic ring cylindrical portion 38 in an interference fit manner. Therefore, the inner circumferential surface of the elastic ring cylindrical portion 38 is in surface contact with the outer circumferential surface of the valve stem guide 18 . The inner annular portion 40 is disposed above the elastic ring cylindrical portion 38 and has a smaller outer diameter and inner diameter than 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 .

The inner annular portion 40 is formed with a main lip 44, a back pressure lip 46, and a plurality of protrusions 48. The outer peripheral surface of the valve stem 14 is in slidable contact with the main lip 44 and the back pressure lip 46 . The main lip 44 is provided mainly to prevent engine oil in the oil chamber 32 from excessively flowing toward the valve stem guide 18. Backpressure lip 46 receives backpressure applied to valve stem seal 30 through gap Ga between valve stem 14 and valve stem guide 18 . The back pressure lip 46 is provided to prevent the main lip 44 from being excessively deformed due to excessive back pressure. The plurality of protrusions 48 are arranged intermittently in the circumferential direction so as to surround the valve stem 14. These protrusions 48 allow the main lip 44 and the back pressure lip 46 to remain on the valve stem 14 even if the valve stem seal 30 is eccentric with respect to the valve stem 14 when the valve stem seal 30 is attached to the valve stem guide 18. They are provided so that they are in contact with substantially uniform contact pressure over the entire circumference.

As shown in FIG. 2, when contacting the valve stem 14, the main lip 44 and the back pressure lip 46 deform and contact 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 small gap (not shown) is provided between the main lip 44 and the outer peripheral surface of the valve stem 14. A small 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 wrapped around the inner annular portion 40. In this embodiment, a circumferential groove 52 for receiving a garter spring 50 is formed on the outer peripheral surface of the inner annular portion 40 . Garter spring 50 presses main lip 44 and projection 48 inward, increasing the contact pressure of main lip 44 and projection 48 against 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 disposed radially outward 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 its entire circumference, and is restrained from moving or expanding in the radial direction.

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

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

The flange 58 is inclined so that the radially outer side thereof is further away from a virtual plane F that is perpendicular to the axis of the rigid ring cylindrical part 54 and includes the end of the rigid ring cylindrical part 54.

Flange 58 has a first surface 60 and a second surface 62. The first surface 60 is located on the opposite side of the main lip 44 in the axial direction of the valve stem guide 18 and contacts 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 , contacts the compression coil spring 29 , and is pressed by the compression coil spring 29 . The flange 58 is inclined, and the first surface 60 has a truncated cone shape with a generating surface that intersects the virtual plane F at an inclination angle θ, and the second surface 62 also It has a truncated conical shape with a generatrix plane that intersects the plane F at an inclination angle θ. In the embodiment, second surface 62 is parallel to first surface 60, but need not be parallel.

The end turn 29A at the lower end (end 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 plane 29B that makes surface contact with the second surface 62 of the flange 58. The inclined plane 29B is also inclined so that the further outward in the radial direction, the further away from the virtual plane F that is perpendicular to the axis of the rigid ring cylindrical part 54, which includes the end of the rigid ring cylindrical part 54. That is, the inclined plane 29B also has a truncated conical shape with a generating surface that intersects the virtual plane F at an inclination angle θ.

Therefore, the first surface 60 of the flange 58 contacts the cylinder head 2, and the second surface 62 of the flange 58 makes surface contact with the inclined plane 29B of the end turn 29A of the compression coil spring 29 on the flange 58 side. 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 plane 29B of the end turn 29A of the compression coil spring 29. By making surface contact with each other, deformation of the flange 58 is suppressed, and the durability of the flange 58 is improved.

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 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 spring seat as well as a retainer for the valve stem seal 30.

Cylinder head 28 has an inclined support surface 28A in surface contact with first surface 60 of flange 58. That is, the support surface 28A also has a truncated cone shape with a generatrix plane 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 large area, and the second surface 62 of the flange 58 is in surface contact with the inclined plane 29B of the end turn 29A of the compression coil spring 29. Make face-to-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, thereby suppressing deformation of the flange 58 and further improving the durability of the flange 58.

FIG. 3 is a partially cutaway perspective view of the sealing structure according to the embodiment, and FIG. 4 is a partially cutaway perspective view of the sealing structure according to the comparative example.

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

In contrast, in the embodiment, the deformation of the flange 58 is suppressed by the inclined second surface 62 of the flange 58 coming into surface contact with the inclined plane 29B of the end turn 29A of the compression coil spring 29 over a wide area. . More preferably, the slanted first surface 60 of the flange 58 makes surface contact over a wide area with the slanted support surface 28A of the cylinder head 2, thereby further suppressing deformation of the flange 58.

Although the invention has been illustrated and described with reference to preferred embodiments thereof, it will be apparent to those skilled in the art that changes in form and detail may be made thereto without departing from the scope of the invention as claimed. One thing will be understood. Such changes, alterations, and modifications are intended to be included within the scope of this invention.

For example, in the embodiment described above, 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 has an inclined plane 29B in surface contact with the second surface 62 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. Conversely, 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 directly contact 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, The cylindrical portion 54 restrains the elastic ring cylindrical portion 38. However, as shown in FIG. 5, in a valve stem seal 30 having a short elastic ring cylindrical portion 38, the valve stem guide 18 may be fitted into the rigid ring cylindrical portion 54.

In the embodiments described above, 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 (a rod that can reciprocate) and a piston guide of a piston-type fuel pump.

The inner circumferential surface of the elastic ring cylindrical portion 38 of the elastic ring 34 may be coated with a resin material that has a small coefficient of friction and is harder than elastomer to facilitate fitting of the valve stem guide 18 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, back pressure lip 46, and protrusion 48 of the elastic ring 34 may be coated with such a resin material to reduce wear thereof.

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

2 Cylinder head (support)
14 Valve stem (rod)
18 Valve stem guide (guide)
28 Spring seat (support plane)
28A Support surface 29A End turn 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 portion 58 Flange 60 First surface 62 Second surface

Claims (3)

a cylindrical guide that guides a rod having a cylindrical portion in a reciprocating manner in the axial direction of the rod;
a support to which the guide is attached;
a sealing device covering an end of the guide;
a compression coil spring pressing the sealing device against the support;
The sealing device has an elastic ring made of an elastic material, and a rigid ring made of a rigid material and fixed to the elastic ring so as to reinforce the elastic ring.
The elastic ring has a lip with which the outer circumferential surface of the rod comes into slidable contact;
The rigid ring has a cylindrical portion disposed radially outward from the end of the guide, and a flange extending radially outward from an end of the cylindrical portion opposite to the lip;
The flange is inclined so that the radially outer side is further away from a plane perpendicular to the axis of the cylindrical portion including the end of the cylindrical portion, and has a first surface that contacts the support body, and a first surface that contacts the support body; has a second surface opposite to the surface and pressed by the compression coil spring;
The compression coil spring is arranged around the cylindrical portion, and the end turn of the flange side end of the compression coil spring has an inclined plane that makes surface contact with the second surface. Sealed structure. The sealing structure according to claim 1, wherein the support body has an inclined support surface that makes surface contact with the first surface of the flange. a cylindrical guide that guides a rod having a cylindrical portion in a reciprocating manner in the axial direction of the rod;
a support to which the guide is attached;
a sealing device covering an end of the guide;
a compression coil spring pressing the sealing device against the support;
The sealing device has an elastic ring made of an elastic material, and a rigid ring made of a rigid material and fixed to the elastic ring so as to reinforce the elastic ring.
The elastic ring has a lip with which the outer circumferential surface of the rod comes into slidable contact;
The rigid ring has a cylindrical portion disposed radially outward from the end of the guide, and a flange extending radially outward from an end of the cylindrical portion opposite to the lip;
The flange is inclined so that the radially outer side is further away from a plane perpendicular to the axis of the cylindrical portion including the end of the cylindrical portion, and has a first surface that contacts the support body, and a first surface that contacts the support body; has a second surface opposite to the surface and pressed by the compression coil spring;
The compression coil spring is arranged around the cylindrical part,
The sealing structure characterized in that the support body has an inclined support surface that makes surface contact with the first surface of the flange.

Images