JP2000204911A - Mounting method of cam receiving plate to tappet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily mount a cam receiving plate to a top surface of a tappet body without using a jointing means such as welding. SOLUTION: A mounting part 5b which has an outer diameter smaller than that of a tappet body 5 and whose outer peripheral surface is a reversed tapered surface diametrally enlarging gradually toward an upper part is formed on an upper part of a top wall 5a of the tappet body 5. An upper faced recess 6a which is complementary to the mounting part 5b is formed on a lower surface of a cam receiving part 6. A central upper surface of the cam receiving part 6 mounted on an upper part of the mounting part 5b is pressed and its peripheral end part is elastically deformed upward, whereby the recess 6a of the cam receiving part 6 is fitted to the mounting part 5b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for easily attaching a hard cam receiving plate to a top surface of a tappet used for a direct-acting valve train in an internal combustion engine.

[0002]

2. Description of the Related Art As shown in FIG. 4, a tappet used in a direct-acting valve train of an internal combustion engine has a concave portion formed on a top surface of a tappet body (1) having a cylindrical shape with a top. Hole (1
In a), a hard shim (2) is detachably fitted and fitted with a cam.
(3) There is one that can prevent abrasion of a surface in sliding contact.

However, in a tappet equipped with such a shim (2), the campet on the top surface of the tappet, ie, the shim (2), is formed by the amount of the concave hole (1a) formed on the top surface.
Since the effective surface area of the sliding contact portion with (3) is small, if the lift amount of the engine valve is to be increased, it is necessary to increase the outer diameter of the tappet body (1) and attach a shim having a large diameter. is there. In addition, this increases the size of the cylinder head, which limits the degree of freedom in engine design.

As a solution to such a problem, there has been proposed a structure in which a hard cam receiving plate (4) is integrally fixed to the entire top surface of a tappet body (1) as shown in FIG. I have.

[0005]

In the conventional tappet shown in FIG. 5, the cam receiving plate (4) is usually fixed by brazing, welding, or the like, which complicates the process and increases the manufacturing cost. .

Further, if the tappet body (1) is formed of an aluminum alloy or the like in order to reduce the inertial mass, materials having greatly different melting points will be joined, so that the joining strength may vary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is intended to easily fix a cam receiving plate to a top surface of a tappet body without using joining means such as welding.
It is an object of the present invention to provide a method of attaching a cam receiving plate to a tappet so that cost can be reduced.

[0008]

According to the present invention, the above-mentioned problem is solved as follows. (1) A method of mounting a hard cam receiving plate having an outer diameter substantially equal to the outer diameter of the tappet main body on the top surface of the tappet main body having a cylindrical top, wherein the upper part of the top wall of the tappet main body is provided. An outer diameter is smaller than the outer diameter of the tappet body, and a mounting portion is formed as a reverse tapered surface whose outer peripheral surface gradually increases upward, and the mounting portion is formed on the lower surface of the cam receiving plate. Forming an upwardly facing concave portion forming a complement with the portion, pressing the upper surface of the central portion of the cam receiving plate placed on the upper surface of the mounting portion,
The concave portion of the cam receiving plate is fitted to the mounting portion by elastically deforming the peripheral end upward.

(2) In the preceding paragraph, at least one of the outer peripheral edge of the upper surface of the mounting portion and the lower edge of the concave portion is chamfered.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a tappet body (5) and a cam receiving plate (6) applied to the present invention.
(5) is made of an aluminum alloy in the shape of a top cylinder, and the cam receiving plate (6) is made of a hard metal material that can be slightly elastically deformed in the thickness direction, for example, chrome molybdenum steel. It is formed with the same diameter as the outer diameter.

The upper end of the top wall (5a) of the tappet body (5) has a slightly smaller diameter than the outer diameter of the tappet body (5), and the outer peripheral surface is gradually tapered upward. A mounting portion (5b) for the cam receiving plate (6) is formed.

The outer peripheral edge (5c) of the upper end of the mounting portion (5b) is chamfered. This chamfer preferably has a roundness.

On the lower surface of the cam receiving plate (6), an upward concave portion (6a) which is complementary to the mounting portion (5b) of the tappet body (5) is formed, and is closely fitted to the mounting portion (5b). Is to be worn.

The cam receiving plate (6) is connected to the top wall (5) of the tappet body (5).
To attach to a), tappet body as shown in Fig. 2
After placing the cam receiving plate (6) on the top surface of the top wall (5a) of (5),
The upper surface of the central portion of the cam receiving plate (6) is strongly pressed by a punch (7) or the like.

Then, the cam receiving plate (6) is elastically deformed as indicated by the imaginary line, and the cam receiving plate (6) is fitted into the mounting portion (5b) by warping the outer periphery slightly upward. You.

When the pressing load of the punch (7) is released after the fitting, the cam receiving plate (6) is elastically restored to the original state as shown in an enlarged view in FIG. It is fitted without looseness and is prevented from coming off.

When the cam receiving plate (6) is pressed, the outer peripheral edge (5c) of the mounting portion (5b) is chamfered.
The contact resistance between the lower end edge of the concave portion (6a) of the cam receiving plate (6) and the outer peripheral edge (5c) is reduced, and the fitting is easily performed. This effect is further promoted if the chamfer is rounded.

The chamfer is made on the opposite side of the cam receiving plate.
It may be formed on the lower edge of the concave portion (6a) of (6), or may be formed on both the outer peripheral edge (5c) of the mounting portion (5b) and the lower edge of the concave portion (6a).

The present invention can be applied to a case where the tappet body (5) is made of iron. That is, when the tappet body (5) is formed of inexpensive carbon steel or the like, and the cam receiving plate (6) is made of a highly wear-resistant material such as the chromium molybdenum steel.

[0020]

According to the first aspect of the present invention, the cam receiving plate can be easily fixed to the top surface of the tappet main body without using joining means such as welding, so that the cost can be reduced. Further, even if the tappet body and the cam receiving plate are made of different materials, they can be attached without any trouble.

According to the second aspect of the present invention, when the cam receiving plate is pressed, the contact resistance between the lower end edge of the concave portion and the outer peripheral edge of the mounting portion is reduced. It is fitted.

[Brief description of the drawings]

FIG. 1 is a front view of a center longitudinal section of a tappet body and a cam receiving plate to which the present invention is applied.

FIG. 2 is a front view of the center longitudinal section showing the mounting procedure of the cam receiving plate.

FIG. 3 is an enlarged vertical sectional front view of a main part after a cam receiving plate is attached.

FIG. 4 is a front view of a tappet using a conventional shim, taken along a central longitudinal section.

FIG. 5 is also a vertical front view of the center of a tappet to which a conventional cam receiving plate is fixed.

[Explanation of symbols]

 (5) Tappet body (5a) Top wall (5b) Mounting part (5c) Peripheral edge (6) Cam receiving plate (6a) Recess (7) Punch

Claims (2)

[Claims] 1. A method of mounting a hard cam receiving plate having an outer diameter substantially equal to an outer diameter of a tappet body on a top surface of a tappet body having a cylindrical shape with a top, wherein a top wall of the tappet body is provided. In the upper part, an outer diameter is smaller than the outer diameter of the tappet main body, and a mounting portion is formed as a reverse tapered surface that gradually expands the outer peripheral surface upward, and on the lower surface of the cam receiving plate, The cam is formed by forming an upward concave portion complementary to the mounting portion, pressing an upper surface of a central portion of a cam receiving plate placed on an upper surface of the mounting portion, and elastically deforming a peripheral end thereof upward. A method of attaching a cam receiving plate to a tappet, wherein a concave portion of a receiving plate is fitted to the mounting portion. 2. The method for mounting a cam receiving plate on a tappet according to claim 1, wherein at least one of an outer peripheral edge of an upper surface of the mounting portion and a lower end edge of the concave portion is chamfered.