JP2002221009A - Tappet for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lighten a tappet and improve wear resistance while securing strength of the tappet. SOLUTION: In this tappet, a cylindrical cover tube 3 of a thin metal formed with a hard coating film 6 on the whole surface, whose upper face is closed is fitted on the whole peripheral face of a tappet body 2 of a low-gravity nonferrous material having a tapped cylindrical shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tappet for an internal combustion engine which is lightweight and has excellent wear resistance.

[0002]

2. Description of the Related Art Conventionally, tappets used for a direct-acting type valve train in an internal combustion engine have been mainly made of an iron-based alloy, but recently, an inertia mass of the valve train has been reduced to reduce the engine mass. In order to further improve the performance, an attempt has been made to form an aluminum alloy or a synthetic resin, and tappets made of an aluminum alloy have been partially put to practical use.

[0003]

The above-mentioned tappets made of an aluminum alloy or a synthetic resin cannot obtain sufficient wear resistance and mechanical strength by themselves. For this reason, the tappet body is made relatively thick to increase rigidity,
It is made of a high-strength material or subjected to surface treatment such as thermal spraying or plating.

[0004] In this case, not only can the tappet be significantly reduced in weight, but also the cost increases, and
If a relatively large stress (Hertz surface pressure) acting on the surface of the tappet is to be received in the surface treatment layer, the thickness of the coating such as thermal spraying or plating needs to be 0.1 mm or more. The cost required for those surface treatments increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a sufficient strength without increasing the thickness of the tappet body or using a high-strength material, and the thickness of the surface treatment layer. By minimizing the weight and cost, and improve the wear resistance.
It is an object to provide a tappet for an internal combustion engine.

[0006]

According to the present invention, the above-mentioned problem is solved as follows. (1) A thin-walled metal cylinder with a closed top surface and a hard coating formed on the entire surface of the entire outer peripheral surface of the tappet body having a cylindrical shape with a low specific gravity and non-ferrous material. Is fitted.

(2) In the above item (1), the low specific gravity non-ferrous material is selected from any of aluminum or magnesium based light metals, synthetic resins, ceramics, and titanium.

(3) In the above item (1) or (2), the thickness of the coating cylinder is set to 0.05 to 0.5 mm, and the coating cylinder is formed by deep drawing.

(4) In the above item (3), the thickness of the top of the coating cylinder is made larger than that of the cylinder.

(5) In any one of the above items (1) to (4), the film thickness is set to 10 to 20 μm, and the film is formed by Ni plating, Cr plating, Ni-P composite plating, hard PVD. , Hard plating by hard CVD, or thermal spraying of a hard material.

(6) In any one of the above items (1) to (5), a solidifying filler having an adhesive property is sealed between the tappet body and the covering cylinder.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a first embodiment of the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. 1. The tappet (1) has a cylindrical shape whose upper surface is closed by a top wall (2a). Tappet body (2) and a thin-walled cylindrical (shown exaggerated in FIG. 1) coating tube fitted to cover the entire outer peripheral surface thereof
(3) and a hard metal tip (5) fitted to the thick portion (2b) at the center of the lower surface of the top wall (2a) and crimped to the shaft end of the engine valve (4). Thus, a hard coating (6) is formed on the entire surface of the coating cylinder (3).

The tappet body (2) is made of aluminum or its alloy, magnesium or its alloy, polyamide,
Engineering plastic which is a hard synthetic resin such as polyacetal and polycarbonate; reinforcing fiber such as glass fiber, carbon fiber and aramid fiber; composite synthetic resin containing any one or more of ceramic whiskers; fine ceramics such as alumina and zirconia ,
It is formed of a non-ferrous material having a low specific gravity such as titanium or its alloy, and the lower end of the outer peripheral surface is chamfered.

The coating cylinder (3) is formed by deep drawing a cold-rolled steel sheet having a thickness of 0.2 to 0.6 mm to form a tappet body.
After forming into a cylindrical shape with a top that is slightly longer than (2), the top (3
The thickness of a) is 0.1 to 0.5 mm, and the thickness of the cylindrical portion (3b) is 0.05.
Finish polishing and the like are performed so as to have a thickness of about 0.3 mm.

The thickness of the top portion (3a) and the thickness of the cylindrical portion (3b) are set within the above-mentioned ranges, because both the weight reduction and strength of the tappet (1) are compatible and the surface of the tappet (1) acts. The reason why the top portion (3a) is slightly thicker than the cylindrical portion (3b) is that the top portion (3a) is subjected to a large load (stress) caused by a cam. Acts repeatedly,
This is to ensure the strength of that part.

After fitting the covering cylinder (3) in close contact with the tappet body (2), as shown in FIG. 2, the lower end portion is bent inward and caulked to prevent it from falling off. .

A film formed on the entire surface of the coating cylinder (3)
(6) is a coating made of Ni or Cr plating, Ni-P composite plating, hard PVD or CVD, or Fe-
C, Fe-Ni, Fe-Cr, W is a thermal spray coating formed by arc spraying, plasma spraying, H.V.O.F.
It has been.

The lower and upper limits of the film thickness are determined by tappets.
It is set in consideration of the abrasion resistance and durability required for (1), the manufacturing cost, and the like.

In the tappet (1) of the above embodiment,
The tappet body (2) is made of a non-ferrous material having a low specific gravity, and its strength and rigidity are compensated for by fitting a coating cylinder (3) made of a thin steel plate, and a stress acting on the surface is received. Therefore, it is not necessary to increase the rigidity by making the tappet body (2) thick, and the tappet (1) can be significantly reduced in weight as compared with an ordinary iron-based alloy.

Further, since the hard and relatively thin film (6) is formed on the surface of the coating tube (3), the coating (6) improves the wear resistance of the tappet (1) and also improves the film ( 6)
The cost required for the formation of the film is also low, and the weight increase due to the formation of the film (6) is extremely small.

FIG. 3 is a partially enlarged view of a second embodiment of the present invention, which differs from the first embodiment in that:
A filler (7) such as an adhesive epoxy resin is sealed in a gap between the tappet body (2) and the covering cylinder (3) as described above.

The filling method of the filler (7) is as follows.
Before fitting (3), a required amount of semi-cured filler (7) is placed on the upper surface of the top wall (2a) of the tappet body (2),
(3) is fitted to the tappet body (2) from above.

Then, the filler (7) placed on the top wall (2a)
The tappet body is pressurized by the top part (3a) of the coating cylinder (3).
Since the fluid flows downward while filling the gap between the surface of (2) and the coating cylinder (3), the gap between the tappet body (2) and the coating cylinder (3) is filled with the filler (7). Sealed.

According to the second embodiment, in addition to the same functions and effects as those of the first embodiment, there is obtained an advantage that the finishing of the top surface and the outer peripheral surface of the tappet body (2) can be omitted. That is, in order to fit the coating cylinder (3) closely to the tappet body (2), it is necessary to finish the top surface and the outer peripheral surface of the formed tappet body (2) to make it a smooth surface. However, the filler (7) is sealed as described above, and the tappet body (2) and the covering cylinder are filled.
If you close the gap between (3), tappet body
There is no particular problem even if the top surface or the outer peripheral surface of (2) is a rough surface.

When the filler (7) is sealed as described above, the filler (7) serves as a binder, and the tappet body (2) and the coating cylinder (3) are integrated with each other. The noise caused by the vibration generated from the tappet (1) can be reduced. In the above embodiment, the hard coating (6) is formed on the entire surface of the coating cylinder (3). However, without forming such a coating (6), the coating cylinder (3) is subjected to heat treatment or carburizing treatment. May be applied to make it hard.

[0026]

According to the first aspect of the present invention, since the stress acting on the surface of the tappet is received by the thin metal jacket, the rigidity of the tappet body is increased by increasing the thickness of the tappet body, or the thickness of the jacket is increased. There is no need to form a film, and the weight and cost of the tappet can be reduced. Further, since a hard coating is formed on the entire surface of the coating cylinder, the abrasion resistance of the tappet is improved.

According to the second aspect of the present invention, since all the materials are lighter than the iron-based alloy, the weight of the tappet body itself can be reduced.

According to the third aspect of the present invention, the strength of the tappet can be increased while minimizing the weight increase of the tappet, and the coating cylinder can be easily formed, so that the cost can be reduced.

According to the fourth aspect of the present invention, even if a large repetitive load is applied by the cam to the top, the strength of the portion does not matter.

According to the fifth aspect of the invention, the abrasion resistance and durability required of the tappet can be sufficiently satisfied, and the surface treatment can be easily performed because of the thin film.
In addition, since all of the films are hard, they have excellent wear resistance.

According to the sixth aspect of the present invention, the tappet body and the covering cylinder are firmly connected to each other with the filler as a binder, and the filler absorbs vibrations, so that the mechanical noise generated from the tappet is reduced. Can be reduced. Further, since there is no need to apply a finishing process or the like to the surface of the tappet body to make it a smooth surface, the processing cost required for it is reduced.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional front view showing a first embodiment of the present invention.

2 is an enlarged view of a portion A in FIG.

FIG. 3 is an enlarged longitudinal sectional view showing a part of a second embodiment of the present invention.

[Explanation of symbols]

 (1) Tappet (2) Tappet body (2a) Top wall (2b) Thick wall (3) Coated cylinder (3a) Top (3b) cylinder (4) Engine valve (5) Chip (6) Coating (7) filler

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G016 AA06 AA19 BA19 BA47 BB04 CA17 CA19 CA35 CA52 EA02 EA07 EA08 EA12 EA14 FA07 FA21 FA24 FA34 FA37 GA01 GA02

Claims (6)

[Claims] 1. A thin metal cylinder having a closed upper surface formed on the entire outer peripheral surface of a tappet main body having a cylindrical shape with a low specific gravity and made of a non-ferrous material, and a hard film is formed on the entire surface. A tappet for an internal combustion engine, wherein a tapping tube is fitted. 2. The tappet for an internal combustion engine according to claim 1, wherein the non-ferrous material having a low specific gravity is selected from aluminum or magnesium based light metals, synthetic resins, ceramics, and titanium. 3. The coating cylinder has a thickness of 0.05 to 0.5 mm,
3. The tappet for an internal combustion engine according to claim 1, wherein the coating cylinder is formed by deep drawing. 4. The tappet for an internal combustion engine according to claim 3, wherein the thickness of the top of the coating cylinder is larger than that of the cylinder. 5. A film having a thickness of 10 to 20 μm, and this film is formed by Ni plating, Cr plating, Ni-P
2. A method according to claim 1, wherein said coating is formed by one of composite plating, hard PVD, hard plating made of hard CVD, and thermal spraying of a hard material.
The tappet for an internal combustion engine according to any one of claims 1 to 4. 6. The tappet for an internal combustion engine according to claim 1, wherein a solidifying filler having an adhesive property is sealed between the tappet body and the covering cylinder.