JPH07310508A - Tappet for internal combustion engine - Google Patents

Abstract

PURPOSE:To shorten a treating time and improve the productivity of a tappet by reducing the treating range of a wear resistant material. CONSTITUTION:A rough part (spiral groove) 4 pointing to a circumferential direction is formed on the outer peripheral surface of a tappet main body 1 and a hardening treatment 5 by a wear resistant material is applied onto this rough part 4. Therefore, the time required in the rough part 4 as a pretreatment or that required it the hardening treatment 5 is reduced by half in comparison with that of a conventional tappet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tappet used in a direct-acting valve operating mechanism in an internal combustion engine, and more particularly to a tappet having improved wear resistance.

[0002]

2. Description of the Related Art A tappet used for a direct-acting valve operating mechanism in an internal combustion engine has hitherto been generally formed of an iron-based material such as steel or cast iron. Aluminum alloy tends to be used for the purpose of further reducing the weight of the valve train.

However, aluminum alloy tappets have lower mechanical strength and inferior wear resistance as compared with those made of iron-based materials. Therefore, this tappet is especially used for cylinder heads made of aluminum alloys of similar materials. If they are incorporated, the sliding surfaces of each other may be worn out early, or a galling phenomenon may occur.

In order to prevent the occurrence of such a problem, conventionally, the entire outer peripheral surface of the tappet has been coated with a wear resistant material different from the base material.

[0005]

As described above, when coating the outer peripheral surface of the tappet, it is necessary to increase the adhesion strength of the wear resistant material to the base material and improve its peeling resistance. As one means for this, there is a case where the entire outer peripheral surface of the tappet is subjected to pretreatment such as blasting to make it rough, and then a coating layer made of an abrasion resistant material is formed by, for example, thermal spraying.

However, as described above, if the entire outer peripheral surface of the tappet is subjected to pretreatment such as blasting and the entire outer peripheral surface is coated with a wear-resistant material, the processing time required for them is increased and the productivity is increased. In addition, the consumption amount of the blast material and the wear resistant material is large, which causes a problem in that the production cost is repelled and the unit price of the product increases.

The present invention has been made in order to solve the above problems, and it is necessary to reduce the treatment range of the pretreatment and abrasion resistant material without impairing the abrasion resistance of the outer peripheral surface. It is an object of the present invention to provide a cheap tappet for an internal combustion engine that shortens the processing time.

[0008]

In order to achieve the above object, the present invention is to form a plurality of rough portions facing in the circumferential direction on the outer peripheral surface of a light metal tappet body having an upper surface closed cylindrical shape, This rough portion is characterized by being subjected to a hardening treatment with an abrasion resistant material. In this case, the rough part is
A spiral groove or an annular groove is preferable (Claim 2). Further, it is desirable that the hardened outer peripheral surface of the tappet body is projected outward by a required dimension from the outer peripheral surface of the tappet body (claim 3). Furthermore, it is desirable that the surface area of the hardening treatment of the rough portion is made larger than that of the central portion by increasing the number or area of the rough portions at the upper and lower ends of the outer peripheral surface of the tappet body (claim 4).

[0009]

[Function] Since a plurality of rough portions facing in the circumferential direction are formed on the outer peripheral surface of the tappet body, and the rough portions are subjected to the hardening treatment with the wear resistant material, the rough portions and the hardening treatment as the pretreatment are performed. The time required is half that of a conventional tappet that covers the entire outer peripheral surface.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the tappet of the present invention, in which a tappet body (1) having a closed upper surface is made of aluminum or an alloy thereof and has a circular recess (2) on the upper surface.
A shim (3) made of a wear-resistant metal material is removably inserted into this.

On the outer peripheral surface of the tappet body (1), a spiral groove having a required depth as a rough portion (for example, 1 to 2 mm) and oriented in the circumferential direction.
(4) is formed, and the spiral groove (4) is subjected to a hardening treatment (5) with a wear resistant material by thermal spraying, plating or the like.

As a material used for the hardening treatment (5), a relatively inexpensive Fe-C-based or Fe-based alloy is preferable in the case of thermal spraying, and Ni-P, Ni in the case of plating.
-Si, Ni-Bn, etc. are suitable.

The pitch of the spiral groove (4), that is, the hardening treatment (5) is such that the upper and lower ends of the outer peripheral surface of the tappet body (1) on which a large surface pressure acts are small and the central part is large.
As a result, the surface area of the hardening treatment (5) applied to the upper and lower parts becomes large.

Further, as shown in the enlarged view of FIG. 2, the outer peripheral surface which has been subjected to the hardening treatment (5) projects outwardly from the outer peripheral surface of the tappet body (1) by a required dimension (for example, 50 to 200 μm). By doing so, when mounted on the cylinder head (6), the outer peripheral surface of the tappet body (1) and the cylinder head (6)
The lubricating oil is effectively retained in the gap (7) formed between (6).

As a method of forming the spiral groove (4), when the tappet body (1) is formed by cold forging, it can be formed by machining after forming, and when it is formed by casting, it can be formed. It can be formed at one time at the same time.

When performing the hardening treatment (5), the spiral groove (4)
The outer peripheral surface of the tappet body (1) except for the above may be masked.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, a plurality of circumferences are provided on the outer peripheral surface of the tappet body (1) instead of the spiral groove (4) described above. The annular groove (8) facing the direction is formed so that the number of grooves at the upper and lower ends of the outer peripheral surface is large and the central part is small, and each annular groove (8) has
Curing treatment (5) was performed using the same materials and means as above.

Also in this second embodiment, the hardening treatment (5)
The outer peripheral surface provided with is projected slightly outward from the outer peripheral surface of the tappet body (1).

As described above, in the tappet of each of the above-described embodiments, the spiral groove as the pretreatment is provided as compared with the conventional tappet body (1) in which the coating layer is formed on the entire outer peripheral surface. Forming (4) and annular groove (8), hardening treatment
The time required for (5) is shortened and productivity is increased.

Further, since the range of the curing treatment (5) is smaller than that in the conventional case, the material required for it can be saved.
Furthermore, since the outer peripheral surface of the hardening treatment is made to protrude beyond the tappet body (1) to retain the lubricating oil, the resistance of the contact surfaces of the cylinder head (6) and the tappet body (1) against each other is improved. Abrasion property is significantly improved.

Since the surface area subjected to the hardening treatment (5) is large at the upper and lower end portions of the outer peripheral surface of the tappet body (1) on which a high surface pressure acts, it is possible to suppress the wear amount of that portion.

After forming the spiral groove (4) and the annular groove (8),
Since it is hardened (5), its adhesion increases,
Good peeling resistance to the base material.

When the hardening treatment (5) has a spiral shape as in the first embodiment, the contact area of the hardening treatment (5) with the cylinder head (6) increases substantially, so that the contact pressure is reduced. Due to the decrease, the amount of wear of the outer peripheral surface of the hardening treatment (5) decreases.

The present invention is not limited to the above embodiments, but can take various modes.

For example, in both of the above embodiments, the curing treatment (5)
Spiral groove (4) or annular groove (8) was formed as a pretreatment before applying, but instead of these, knurling, blasting or chemical treatment (sulfate coating, phosphate coating)
For example, a rough portion may be formed on the surface of the tappet body (1). Also by this, the adhesion strength of the curing treatment (5) can be increased.

Further, as a curing treatment (5), an anodized film
(Alumite treatment) or curing treatment
As the material of (5), a synthetic resin having excellent wear resistance, self-lubricating property, mechanical strength and the like, for example, ultrahigh molecular weight polyethylene, polyacetal, fluororesin, polyamide, polybutylene terephthalate, etc. may be used.

When the above synthetic resin material is used, not only the sliding friction resistance becomes smaller, but also the tappet can be made lighter and the spiral groove (4 ) Etc. have the advantage that they can be easily molded.

In the embodiment, the surface area of the hardening treatment (5) is increased by increasing the number of spiral grooves (4) and annular grooves (8) formed at the upper and lower ends of the outer peripheral surface of the tappet body (1). Although it is large and the wear resistance of that part is improved, the groove width is increased by increasing the groove width of the spiral groove (4) etc.
The surface area of (5) may be increased.

[0029]

The present invention has the following effects. (a) Since the range of curing treatment is smaller than that of conventional tappets, the time required for pretreatment and curing treatment can be shortened, productivity can be improved, and cost can be reduced. Moreover, the wear resistance of the outer peripheral surface of the tappet can be improved.

(B) According to the second aspect of the invention, the adhesion strength of the material which has been subjected to the curing treatment is increased, and the peeling resistance is improved.

(C) According to the third aspect of the invention, since the oil retaining property of the lubricating oil is improved, the amount of wear of the contact surfaces of the cylinder head and the tappet with each other is significantly reduced.

(D) According to the invention described in claim 4, it is possible to suppress the wear of the upper and lower end portions of the outer peripheral surface of the tappet, which is subjected to a high surface pressure.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the hardening treatment forming portion in FIG.

FIG. 3 is a partially cutaway front view of the same second embodiment.

[Explanation of symbols]

 (1) Tappet body (2) Recess (3) Shim (4) Spiral groove (rough part) (5) Hardening treatment (6) Cylinder head (7) Gap (8) Annular groove (rough part)

Claims (4)

[Claims] 1. A cylindrical light metal tappet body with a closed top surface is provided with a plurality of rough portions facing in the circumferential direction, and the rough portions are hardened with a wear resistant material. A tappet for an internal combustion engine, which is characterized in that 2. The rough portion is a spiral groove or an annular groove.
The described tappet for an internal combustion engine. 3. The tappet for an internal combustion engine according to claim 1, wherein the hardened outer peripheral surface is projected outwardly by a required dimension from the outer peripheral surface of the tappet body. 4. The number or area of rough portions is increased at the upper and lower end portions of the outer peripheral surface of the tappet body, so that the surface area of the hardening treatment at that portion is made larger than that at the central portion. Item 12. A tappet for an internal combustion engine according to any one of items 1 to 3.