JP2009257509A - Valve stem seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve stem seal 1, capable of sealing a section between a valve stem 4 of intake/exhaust valve of an internal combustion engine and a valve guide 3 for supporting the valve stem to move freely in the axial direction and preventing penetration and leakage from the valve guide 3, made of sintered metal. <P>SOLUTION: This valve stem seal 1 is provided with a valve guide seal part 11 which is brought into close contact with an outer peripheral face of the cylindrical valve guide 3 that protrudes from a cylinder head 2 and a sealing lip 12, extended from a tip part of the valve guide seal part 11 and brought into close contact with an outer peripheral face of the valve stem 4 which is slidably inserted into the valve guide 3. A seating seal part 13, which is to be brought into close contact with the cylinder head 2, is formed in an end part, on a side opposite to the sealing lip 12 in the valve guide seal part 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a valve stem seal that seals between a valve stem of an intake / exhaust valve of an internal combustion engine and a valve guide that supports the valve stem so as to be axially movable.

  A valve stem seal is sealed between a valve stem of an intake / exhaust valve of the internal combustion engine and a valve guide that supports the valve stem so as to be axially movable. FIG. 4 is a cross-sectional view showing a valve of an internal combustion engine provided with a conventional valve stem seal, and FIG. 5 is a cross-sectional view in a mounted state showing the conventional valve stem seal.

  In FIG. 4, reference numeral 101 is a cylinder head, 102 is an exhaust port formed in the cylinder head 101, 103 is a valve for opening and closing the intake port (or exhaust port) 102, 104 is a valve stem extending from the valve 103, and 105 is a cylinder. A valve guide penetrating the head 101 and supporting the valve stem 104 so as to be movable in the axial direction, 106 a spring for biasing the valve 103 through the valve stem 104 in the valve closing direction, and 107 at the upper end of the valve stem 104 The cam is brought into contact with the provided lifter 108 and pushes down the valve 103 in the valve opening direction against the urging force of the spring 106 every time the camshaft 107a makes one rotation. A valve stem seal 110 is attached to the valve guide 105.

Specifically, as shown in FIG. 5, the valve stem seal 110 includes a valve guide seal portion 111 that is tightly fitted to the upper outer peripheral surface of the valve guide 105, and extends from the upper end of the valve guide seal portion 111. The engine lip in the oil chamber O formed on the upper side of the valve guide 105 is composed of a seal lip 112 that is slidably contacted and a reinforcing sleeve 113 embedded in the valve guide seal 111. This prevents leakage from the shaft circumferential gap G of the valve stem 104 (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 6-40304

  By the way, in recent years, as an environmental measure, there has been a demand for higher output of an internal combustion engine and improvement of fuel consumption, and studies on multi-valve and variable valve mechanisms of the internal combustion engine are being advanced. Accordingly, the valve stem seal 110 is also required to reduce the amount of oil leakage and reduce the change in the amount of oil leakage when the valve operation changes.

  However, in this type of valve stem seal 110, the amount of oil leakage from the intimate sliding portion between the outer peripheral surface of the valve stem 104 and the seal lip 112 is sufficiently suppressed, rather, other parts, specifically, It is considered that countermeasures are required for permeation leakage from the valve guide 105. That is, a sintered metal is used for the valve guide 105, and since such a sintered metal has a porous structure, oil leaks through innumerable fine pores inside.

  Further, in the case where the valve 103 is an intake valve, if the intake port 102 side becomes negative pressure, it is considered that a change in the amount of oil leakage increases due to a suction phenomenon from the fine holes of the valve guide 105.

  The present invention has been made in view of the above points, and its technical problem is to provide a valve stem seal having a structure capable of preventing permeation leakage from a valve guide made of sintered metal. It is to provide.

  As means for effectively solving the above technical problem, a valve stem seal according to the present invention includes a valve guide seal portion that is in close contact with the outer peripheral surface of a cylindrical valve guide that protrudes from a cylinder head, and the valve guide. A seal lip extending from the tip of the seal portion and slidably in contact with the outer peripheral surface of the valve stem inserted through the valve guide, and an end opposite to the seal lip in the valve guide seal portion A seating seal portion that is in close contact with the cylinder head is formed in the portion.

  More preferably, in the above configuration, a spring receiver is formed on the reinforcing sleeve provided integrally with the valve guide seal portion.

  According to the valve stem seal of the present invention, the valve guide protruding from the cylinder head is slidably in contact with the outer peripheral surface of the valve stem, and the valve guide seal portion is in close contact with the outer peripheral surface of the valve guide. And is surrounded by a seating seal portion that is formed at the end portion thereof and is in close contact with the cylinder head, so that even if the valve guide has a porous structure, permeation leakage from the valve guide is effectively prevented. be able to.

  Further, by forming the spring receiver on the reinforcing sleeve provided integrally with the valve guide seal portion, it is not necessary to separately provide a metal fitting for receiving the spring for operating the valve, and the number of parts can be reduced.

  Hereinafter, a preferred embodiment of a valve stem seal according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a mounted state showing a first form of a valve stem seal according to the present invention, and FIG. 2 is a main part cross-sectional view showing a shape change example in the first form.

  In FIG. 1, reference numeral 1 is a valve stem seal according to the present invention, reference numeral 2 is a cylinder head of an internal combustion engine, reference numeral 3 is a cylindrical shape that penetrates the cylinder head 2 and protrudes upward from the cylinder head 2. A valve guide made of sintered metal, reference numeral 4 is a valve stem inserted through the valve guide 3 and formed with a valve (not shown) at the lower end, and reference numeral 5 biases the valve through the valve stem 4 in the valve closing direction. A valve spring, reference numeral 6 is a spring seat that contacts the lower end portion 5 a of the valve spring 5.

  The valve stem seal 1 includes a valve guide seal portion 11, a seal lip 12 that extends from a tip portion (upper end portion) of the valve stem seal 1 and is slidably in contact with an outer peripheral surface of the valve stem 4, and a valve guide seal portion 11. A seating seal portion 13 formed at an end opposite to the seal lip, a valve guide seal portion 11 and a reinforcing sleeve 14 for reinforcing the seating seal portion 13, and a garter spring 15 attached to the outer periphery of the seal lip 12; Is provided. The valve guide seal portion 11, the seal lip 12, and the seating seal portion 13 are formed continuously from each other with a rubber material or a synthetic resin material having rubber-like elasticity, and are integrally formed with a metal reinforcing sleeve 14. is there.

  The reinforcing sleeve 14 in the valve stem seal 1 includes a cylindrical sleeve body portion 14a, an inward flange portion 14b that is bent at the upper end thereof, and an outward flange portion 14c that is bent at the lower end thereof. Is longer than the protruding length of the valve guide 3 from the cylinder head 2.

  The valve guide seal portion 11 in the valve stem seal 1 is integrally vulcanized and bonded to the inner peripheral surface of the sleeve main body portion 14 a of the reinforcing sleeve 14, and suitable for the outer peripheral surface of the valve guide 3 protruding from the cylinder head 2. It is to be intimately closed. A required number of engaging grooves 3 a extending continuously in the circumferential direction are formed on the outer peripheral surface of the valve guide 3, and one of the inner peripheral surfaces of the valve guide seal portion 11 is formed in the engaging groove 3 a. When the portion 11a bites in, a large resistance (prevention force) is generated against the valve stem seal 1 (valve guide seal portion 11) coming out of the valve guide 3.

  The seal lip 12 in the valve stem seal 1 extends upward from the vicinity of the inner diameter end portion of the inward flange portion 14 b of the reinforcing sleeve 14, and the inner diameter portion near the tip (upper end) projects from the upper end opening of the valve guide 3. It is slidably in close contact with the outer peripheral surface of the stem 4.

  The seating seal portion 13 in the valve stem seal 1 is formed on the lower surface of the outward flange portion 14c of the reinforcing sleeve 14 continuously from the valve guide seal portion 11, and is in close contact with the upper surface of the cylinder head 2 with an appropriate surface pressure. Is.

  The garter spring 15 is formed by connecting metal coil springs in an annular shape, and is fitted into an annular groove formed in the outer peripheral surface near the tip (upper end) of the seal lip 12, and is attached to the outer peripheral surface of the valve stem 4. This compensates for the tightening force of the seal lip 12.

  The spring seat 6 is formed in an annular shape by a metal punching press or the like, and is interposed between the lower end portion 5 a of the valve spring 5 and the cylinder head 2 on the outer peripheral side of the valve stem seal 1.

  The valve stem seal 1 of the first embodiment configured as described above has the valve guide seal portion 11 on the outer peripheral surface of the valve guide 3 until the seating seal portion 13 is brought into close contact with the cylinder head 2 with an appropriate surface pressure. Mounted by press-fitting. In this mounted state, the seal lip 12 is slidably brought into close contact with the outer peripheral surface of the valve stem 4 on the upper side of the valve guide 3, and the engine oil in the oil chamber O existing on the upper side of the cylinder head 2 is transferred to the valve stem 4. Is prevented from leaking into the gap G between the outer peripheral surface of the valve guide 3 and the inner peripheral surface of the valve guide 3.

  Here, the valve guide 3 is made of sintered metal and has a porous structure having innumerable fine pores. The valve guide 3 has a valve guide seal portion 11 in close contact with the outer peripheral surface thereof. Engine oil in the oil chamber O because the seal lip 12 in close contact with the outer peripheral surface of the valve stem 4 and the seating seal portion 13 in close contact with the cylinder head 2 are completely surrounded. Does not penetrate into the valve guide 3 from the outer peripheral side. Accordingly, it is possible to effectively prevent permeation leakage through the valve guide 3, and thus it is possible to reduce the change in the amount of oil leakage.

  In addition, the seating seal part 13 can further improve the sealing performance by forming a seal protrusion 13a as shown in FIG.

  Next, FIG. 3 is a sectional view of the mounted state showing a second form of the valve stem seal according to the present invention. In this embodiment, the difference from the first embodiment described above is that the enlarged diameter portion 14d and the spring receiver 14e are formed on the reinforcing sleeve 14. The other parts are basically configured in the same manner as in FIG.

  Specifically, the reinforcing sleeve 14 in the second embodiment is a cylindrical sleeve body portion 14a, an inward flange portion 14b bent at the upper end thereof, and a lower portion of the valve spring 5 formed at the lower portion of the sleeve body portion 14a. A diameter-enlarged portion 14d that can be loosely fitted to the inner periphery of the cylinder, and a spring receiver 14e formed in the shape of an outward flange at the lower end of the enlarged-diameter portion 14d. 3 is longer than the protruding length of 3.

  The seating seal portion 13 is formed at the lower end of the valve guide seal portion 11 that reaches the inner periphery of the enlarged diameter portion 14d. When the seating seal portion 13 is not attached, the seating seal portion 13 is slightly below the lower surface of the spring receiver 14e. It protrudes. Accordingly, when the spring receiver 14e is in contact with the upper surface of the cylinder head 2, the seating seal portion 13 is brought into close contact with the upper surface of the cylinder head 2 in a properly compressed state.

  In the valve stem seal 1 of the second configuration configured as described above, the valve guide seal portion 11 is press-fitted into the outer peripheral surface of the valve guide 3 until the spring receiver 14e of the reinforcing sleeve 14 contacts the cylinder head 2. It is attached by doing. In this mounted state, the valve guide seal portion 11 is in close contact with the outer peripheral surface of the valve guide 3 protruding from the cylinder head 2 with an appropriate tightening margin, and the seating seal portion 13 is attached to the cylinder head 2 with an appropriate surface pressure. The seal lip 12 is in close contact with the outer peripheral surface of the valve stem 4 on the upper side of the valve guide 3 so as to be slidable. Can be prevented from leaking into the gap G between the outer peripheral surface of the valve stem 4 and the inner peripheral surface of the valve guide 3, and permeation leakage through the valve guide 3 can be prevented.

  In addition, since the spring receiver 14e is integrally formed with the reinforcing sleeve 14, there is no need to separately provide the annular spring seat 6 as in the first embodiment, and therefore the number of parts can be reduced, and the reinforcement The enlarged diameter portion 14d formed on the sleeve 14 also has an effect of suppressing the rattling of the valve spring 5.

  In addition, since the urging force of the valve spring 5 presses the valve stem seal 1 toward the cylinder head 2 via the spring receiver 14e, the valve stem seal 1 can be reliably prevented from coming off.

It is sectional drawing of the mounting state which shows the 1st form of the valve stem seal which concerns on this invention. It is principal part sectional drawing which shows the example of a shape change in a 1st form. It is sectional drawing of the mounting state which shows the 2nd form of the valve stem seal which concerns on this invention. It is sectional drawing which shows the valve | bulb of the internal combustion engine which provided the conventional valve stem seal. It is sectional drawing of the mounting state which shows the conventional valve stem seal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Valve stem seal 11 Valve guide seal part 12 Seal lip 13 Seating seal part 14 Reinforcement sleeve 14d Expanded diameter part 14e Spring receiver 2 Cylinder head 3 Valve guide 4 Valve stem 5 Valve spring 6 Spring seat

Claims (2)

  A valve guide seal portion that is in close contact with the outer peripheral surface of the cylindrical valve guide that protrudes from the cylinder head, and extends from the distal end portion of the valve guide seal portion and slides on the outer peripheral surface of the valve stem that is inserted through the valve guide. A valve stem comprising a seal lip that is movably brought into close contact, and a seat seal portion that is in close contact with the cylinder head is formed at an end of the valve guide seal portion opposite to the seal lip. sticker.   The valve stem seal according to claim 1, wherein a spring receiver is formed on a reinforcing sleeve provided integrally with the valve guide seal portion.

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