JPH11294117A - Tappet for internal combustion engine - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a quiet valve train by absorbing and attenuating tappet vibration. SOLUTION: A small-diameter cylindrical portion is formed at a central portion of a cylindrical portion of a tappet body excluding upper and lower ends, and a porous vibration isolator 13 is fixed to an outer peripheral surface thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tappet used for a direct-acting valve train in an internal combustion engine.
The present invention relates to a tappet capable of reducing noise due to vibration.

[0002]

2. Description of the Related Art FIG. 3 schematically shows a direct-acting type valve operating mechanism of an internal combustion engine. An engine valve (2) is mounted on a cylinder head (1) by a valve spring or a spring retainer (not shown). It is assembled.

[0003] The tappet (3) is an aluminum alloy topped cylindrical tappet body composed of a top wall (4a) and a cylindrical portion (4b).
(4) and a hard metal shim (6) removably fitted in a recess (5) on the top surface of the top wall (4a).
a) a hard metal tip (7) fitted to the center of the lower surface of Guide hole (1
It is slidably fitted in a). On the upper surface of the shim (6),
The cam (8) comes into contact via a required valve clearance.

[0004]

The main noises generated by the direct-acting valve train as described above include a striking sound when the nose of the cam (8) comes into contact with the shim (6) and an engine. There are an impact sound when the valve (2) is seated on a valve seat (not shown), a friction sound and a slap sound when the tappet (3) slides in the guide hole (1a), and the like. In particular, the slap noise tends to increase as wear on the outer peripheral surface of the guide hole (1a) and the cylindrical portion (4b) progresses.

[0005] These noises are emitted via the tappet (3). That is, the tappet (3) is the tappet body
(4) and the shim (6) are made of metal, and when vibration is transmitted to them, they are hardly attenuated and resonate. Tappet
(3) In order to reduce the noise generated, the weight of the valve train can be further reduced, the profile of the cam (8) can be changed, and the clearance between the cylinder (4b) and the guide groove (1a) can be reduced. It is effective to reduce the input load to the tappet (3) by minimizing the load as much as possible.

However, since there is a limit in terms of cost, engine performance, reliability, and the like, there has been no countermeasure against the noise generated from the tappet as an inevitable noise. Is the actual situation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and effectively reduces and reduces noise such as slap noise by effectively absorbing and attenuating vibration applied to a tappet body. It is an object of the present invention to provide a tappet for an internal combustion engine in which a system is obtained.

[0008]

According to the present invention, the above-mentioned problem is solved as follows. (1) In a tappet for an internal combustion engine having a cylindrical shape with a top having a top end closed by a top wall, the outside diameter of the center portion of the cylinder portion excluding the upper and lower ends is made small, and the outer peripheral surface is prevented. Fix the vibration material.

(2) In the above item (1), the vibration-proof material is made porous.

(3) In the above item (1), the closing cylinder is fixed to the outer peripheral surface of the vibration isolator.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The same members as those in the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 schematically shows a valve train to which the first and second embodiments of the present invention are applied.
Consists of an aluminum alloy tappet body (4) composed of a top wall (4a) and a cylindrical portion (4b), a shim (6) and a tip (7), as in the prior art. The outer peripheral surface of the small-diameter cylindrical portion (9) formed at the center except the upper and lower ends has heat resistance
An oil-resistant vibration isolator (10) is integrally fixed by baking or bonding.

As the vibration damping material (10), butyl rubber, fluorine rubber, soft plastic, or the like is suitable, and its thickness is, for example, in consideration of the weight increase of the tappet (3).
It is preferably about 0.5 to 1.0 mm. Further, the vibration-proof material (10) is made porous by mixing a foaming agent into each of the above-mentioned materials and molding.

A very small gap is formed between the outer peripheral surface of the vibration isolator (10) and the inner surface of the guide hole (1a) of the cylinder head (1). An increase in frictional resistance due to contact with the guide hole (1a) is prevented.

The reason why the vibration isolator (10) is provided at the center of the cylindrical portion (4b) is that the stress acting on this portion is the smallest, and there is no problem in strength even if this portion has a small diameter. That is, in this type of tappet (3), a bending moment about the contact portion with the engine valve (2) acts due to the rotational movement of the cam (8), and the bending stress due to this is:
It mainly acts on the upper and lower ends of the cylindrical portion (4b). Therefore, fixing the anti-vibration material (10) with the upper and lower ends also having a small diameter,
It is not preferable in view of the strength of the tappet (3).

When the vibration isolator (10) is fixed to the outer peripheral surface of the cylindrical portion (4b) of the tappet (3) as in the above-described embodiment, the vibration of the tappet (3) accompanying the valve movement, particularly, Vibration when the tappet (3) moves up and down in the guide hole (1a) of the cylinder head (1) is effectively absorbed and attenuated by the vibration isolator (10),
Friction noise generated from the tappet (3) can be reduced.

The above-mentioned friction noise becomes slap noise when the outer peripheral surfaces of the guide hole (1a) and the cylindrical portion (4b) are worn due to long-term use and the gap between the sliding surfaces becomes large. Although there is a tendency, this slap noise is also attenuated and reduced, so that a quiet valve train can be obtained.

In addition, since the vibration isolator (10) is made porous, the lubricating oil has a high oil retaining property and the sliding surface between the guide hole (1a) and the cylindrical portion (4b) is effectively lubricated. Thereby, the abrasion of the contact surfaces can be suppressed, and as a result, the slap noise is further reduced.

As described above, making the vibration-proof material (10) porous and having oil-retaining property is achieved particularly by using an aluminum alloy tappet (3) which is considered to be less wear-resistant than an iron tappet.
It is effective for

FIG. 3 shows an embodiment of the invention according to the third aspect. In this embodiment, an iron tappet (11) having no shim (6) or chip (7) as in the above embodiment is used. Applied.

The tappet (11) comprises a top wall (11a) and a tubular portion (11b), and a small-diameter tubular portion (12) formed at the center of the outer peripheral surface of the tubular portion (11b) has the same material as described above. An anti-vibration material (13) made of (not porous) is fixed, and its outer peripheral surface is thin (about 0.1 to 0.5 mm) of, for example, stainless steel or plastic.
Is covered with a closing cylinder (14). A slight gap is formed between the outer peripheral surface of the closing cylinder (14) and the inner surface of the guide hole (1a).

When the wear-resistant closing cylinder (14) is used, its outer peripheral surface may be brought into contact with the guide hole (1a).

Also in this embodiment, the friction noise of the tappet (11) can be reduced in the same manner as described above.

Further, since the outer peripheral surface of the vibration isolator (13) is covered, it is prevented from contacting the lubricating oil, and there is no danger that the durability will be reduced due to the deterioration over time.

It is to be noted that such a closed cylinder (14) is omitted,
The vibration damping material (13) may be used alone, or a porous vibration damping material (10) similar to the embodiment shown in FIG. 1 may be used.

[0026]

According to the present invention, since the vibration of the tappet body is absorbed by the vibration isolator, the slap noise and the like are particularly effectively reduced, and a quiet valve operating system can be obtained.

According to the second aspect, in addition to the above-mentioned effects, the holding ability is enhanced, so that the sliding surface between the cylinder head and the cylindrical portion is effectively lubricated, and the abrasion of the contact surfaces of each other can be suppressed. .

According to the third aspect, the vibration-proof material is prevented from coming into contact with the lubricating oil, so that its durability can be improved, and it is not necessary for the vibration-proof material to have oil resistance. In addition, the range of choice of the material is widened, and it can be implemented at low cost.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional front view of a main part of a valve train to which an embodiment of the invention described in claims 1 and 2 is applied.

FIG. 2 is a front view in central section of a main part of a valve train to which an embodiment of the invention described in claim 3 is applied.

FIG. 3 is a central longitudinal sectional front view of a main part of a valve train including a conventional tappet.

[Explanation of symbols]

 (1) Cylinder head (1a) Guide hole (2) Engine valve (3) (11) Tappet (4) Tappet body (4a) (11a) Top wall (4b) (11b) Tube part (5) Concave hole (6 ) Shim (7) Tip (8) Cam (9) Small-diameter cylinder (10) (13) Vibration isolator (14) Occlusion cylinder

Claims (3)

[Claims] 1. A tappet for an internal combustion engine having a cylindrical shape with a top having an upper end closed by a top wall, wherein an outer diameter of a central portion of the cylindrical portion excluding upper and lower ends is made small, and an outer peripheral surface thereof is provided. A tappet for an internal combustion engine, wherein a vibration damping material is fixed to the tappet. 2. The tappet for an internal combustion engine according to claim 1, wherein the vibration-proof material is porous. 3. The tappet for an internal combustion engine according to claim 1, wherein a closing cylinder is fixed to an outer peripheral surface of the vibration isolator.