JPH0874528A - Tappet for internal combustion engine - Google Patents

Abstract

PURPOSE: To improve manufacturing efficiency of a tappet by omitting working process of a recessed part on the upper surface of the top wall of a tappet main body provided with its top. CONSTITUTION: A shim 10 wherein an upward fitting part 14 is provided approximately in the center part on the lower surface is fitted into a holding hole 9 formed on the upper surface of a top wall 7 of a top provided tappet main body 6, and a roughened surface 13 left in the center part in processing of the upper surface of the top wall 7 is surrounded and covered with the fitting part 14.

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 operating mechanism in an internal combustion engine.

[0002]

2. Description of the Related Art FIG. 2 schematically shows a direct-acting valve operating mechanism that is widely used in a DOHC engine. An engine valve (01) includes a pair of cotters (02) (02) and springs. Cylinder head with retainer (03), valve spring (04), etc.
It is attached to (05).

At the upper end of the engine valve (01), a tappet body (06) whose upper surface is closed by a top wall (07) is attached to the top wall (0
The inner bottom surface of 7) is fitted and inserted from above so as to abut the stem end of the engine valve (01).

[0004] An annular side wall (0
A disc-shaped holding hole (09) is formed on the inside of 8), and a shim (010) for valve clearance adjustment is fitted in the holding hole (09). A tappet (A) is formed by the shim (010) and the tappet body (06).

A concave portion (0
12) has been formed. The recessed part (012) is provided for the following reason.

There is a step of inserting a disc-shaped grindstone (not shown) into the storage hole (09) of the tappet body (06) shown in FIG. 3 and grinding the inner surface thereof. However, since the peripheral speed of the center of the grindstone is slow, it cannot be ground completely, and a rough surface (01
3) may remain.

Therefore, the rough surface (01
By forming the recessed portion (012) in a portion where 3) may remain, the labor of finishing the rough surface by another process is omitted.

[0008]

To provide the recessed portion (012) on the upper surface of the top wall (07), the recessed portion (012) is cut by a cutting tool as the primary processing, and then the grindstone is used as the secondary processing. The holding hole (09) must be ground by. Therefore, the processing process of the tappet body (06) becomes complicated, and the tappet
The manufacturing efficiency of (A) decreases.

The present invention has been made to solve the above-mentioned problems, and provides a tappet for an internal combustion engine, which eliminates the step of processing the recessed portion in the tappet body and improves the manufacturing efficiency of the tappet. The purpose is to do.

[0010]

According to the present invention, the above problems can be solved as follows. (1) An annular side wall is connected upward to the outer peripheral edge of the top wall of the cylindrical tappet body whose upper surface is closed by the top wall, and a valve clearance is provided in a holding hole formed in the side wall. In a tappet for an internal combustion engine in which a disc-shaped shim for adjustment is detachably fitted, it remains in substantially the central portion of the lower surface of the shim, and in the substantially central portion when processing the upper surface of the top wall. An upward recess is provided to surround and cover the rough surface. (2) An annular side wall is provided upwardly on the outer peripheral edge of the upper surface of the side wall of the cylindrical tappet body whose upper surface is closed by the top wall, and the valve clearance is adjusted in the holding hole formed in this side wall. In a tappet for an internal combustion engine, in which a disc-shaped shim for use in the vehicle is detachably fitted, between the top wall and the shim in the holding hole, when the upper surface of the top wall is machined, it remains in the substantially central portion thereof. An annular spacer having a circular hole with a size capable of enclosing the rough surface is provided in the center.

[Action]

According to the first aspect of the present invention, the rough surface left substantially in the center of the upper surface of the top wall is covered by the upward recessed portion provided on the lower surface of the shim, and the lower surface of the shim is the recessed portion. Except for the part, it adheres to the bottom of the holding hole.

According to the second aspect of the invention, since the rough surface is housed in the circular hole in the spacer, the lower surface of the shim does not come into direct contact with the rough surface.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described in detail with reference to FIG. It should be noted that the same members as those described in the conventional example are denoted by the same reference numerals except the initial (0), and the detailed description thereof is omitted.

In FIG. 1, an upward concave portion (14) is formed in the lower surface of the shim (10) substantially in the center thereof. Top wall
During the grinding process of (7), the rough surface (13) remaining in the center of the upper surface is surrounded and covered by the upward recessed portion (14), and the shim ( The lower surface of 10) is in close contact with the bottom surface of the holding hole (9).

With the above-mentioned structure, even if the shim (10) is rotated by the engine valve or cam in the compression direction and the shim (10) rotates in the holding hole (9), the rough surface
The (13) does not come into contact with the lower surface of the shim (10), the frictional force becomes large, and the lower surface of the shim (10) and the upper surface of the top wall (7) are not scratched or worn. Absent.

As a result, the conventional step of forming the recessed portion on the upper surface of the top wall (7) is not required, so that the working time is reduced and the manufacturing efficiency of the tappet (A) is increased.

Using powder metallurgy to produce the shim (10),
The production is further facilitated, and the production efficiency of the tappet (A) is further improved.

Further, the shim (10) is prepared by the powder metallurgy method.
The base material may be punched by a press, and then the recessed portion (14) may be formed by an appropriate method.

The shape of the recessed portion (14) is not limited to the above-mentioned embodiment, but various applications can be carried out.

Next, a second embodiment of the present invention will be described with reference to FIG. The same members as those described in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The shim (10) and the top wall (7) in the storage hole (9)
An annular spacer (16) having a diameter substantially the same as the outer diameter of the shim (10) and having a circular hole (15) in the central portion is detachably fitted between and. The spacer (16) has a rough surface (13)
Has a minimum thickness that does not project above the upper surface of the circular hole (15), and the circular hole (15) has an inner diameter capable of surrounding the region of the rough surface (13). The lower surface of the shim (10) is a flat surface so that it can be brought into close contact with the spacer (16).

When the shim (10) is brought into close contact with the upper surface, the circular hole (1
5) is hidden by the bottom surface of the shim (10) and is a spacer
The lower surface of (16) is in close contact with the bottom surface of the holding hole (9). Therefore, even if the shim (10) rotates in the holding hole (9), the rough surface
Since (13) is surrounded by the circular hole (15) in the spacer (16), it does not come into contact with the lower surface of the shim (10). Therefore, the friction force becomes large, and the bottom surface or top wall of the shim (10) is
The upper surface of (7) is not scratched or worn.

A circular hole is also provided between the shim (10) and the top wall (7).
Since the spacer (16) having (15) is provided, there is an advantage that the processing step of providing the recessed portion (14) in the shim (10) as in the first embodiment can be omitted.

Furthermore, since the spacer 16 does not require abrasion resistance, an inexpensive low-grade material can be used.
Therefore, if the valve clearance is adjusted by preparing a plurality of spacers (10) having different thicknesses, it is cheaper than preparing a plurality of shims (10).

[0025]

The present invention can bring the following effects. (a) Since the rough surface remaining on the upper surface of the top wall is surrounded and covered by the recessed portion on the lower surface of the shim, the adhesion of the shim does not become incomplete (claim 1).

(B) Since the recess is formed substantially in the center of the lower surface of the shim, the step of forming the recess in the center of the upper surface of the top wall after grinding the storage hole, which is conventionally required, becomes unnecessary. .
Therefore, the tappet processing steps are reduced, and the tappet manufacturing efficiency is increased (Claim 1).

(C) Since the rough surface formed on the upper surface of the top wall is surrounded and covered by the recessed portion formed on the lower surface of the shim, the lower surface of the shim and the upper surface of the top wall are scratched or subjected to large friction. No wear occurs (claim 1).

(D) By providing a spacer having a circular hole between the shim and the top wall, it is possible to prevent abrasion of the shim, and in this case, the shim is provided with a recessed portion. The work can be omitted. (Claim 2).

[Brief description of drawings]

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

FIG. 2 is a central vertical sectional front view showing a second embodiment of the present invention.

FIG. 3 is a central longitudinal front view showing a conventional tappet and a direct acting valve operating mechanism.

FIG. 4 is a central longitudinal front view of the tappet body.

[Explanation of symbols]

 (6) Tappet body (7) Top wall (8) Side wall (9) Holding hole (10) Shim (13) Rough surface (14) Recessed portion (15) Circular hole (16) Spacer (A) Tappet

Claims (2)

[Claims] 1. A cylindrical tappet main body having an upper surface closed by a top wall, and an annular side wall is continuously connected to an upper peripheral edge of an upper surface of the top wall, and a holding hole formed in the side wall is provided. In a tappet for an internal combustion engine in which a disc-shaped shim for valve clearance adjustment is detachably fitted, in a substantially central portion of the lower surface of the shim, and in a substantially central portion when machining the upper surface of the top wall. A pet for an internal combustion engine, which is provided with an upward recessed portion that surrounds and covers the remaining rough surface. 2. A valve is provided in such a manner that an annular side wall is continuously connected upward to an outer peripheral edge of an upper surface of a side wall of a cylindrical tappet body whose upper surface is closed by a top wall, and a retaining hole formed in the side wall. In a tappet for an internal combustion engine in which a disc-shaped shim for clearance adjustment is detachably fitted, between the top wall and the shim in the holding hole, when processing the upper surface of the top wall, a substantially central portion thereof A tappet for an internal combustion engine, wherein an annular spacer having a circular hole having a size capable of enclosing the remaining rough surface in the center is provided.