JPH1193626A - Tappet for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an effective surface area of the upper surface of a cam receiving plate from being reduced and facilitate replacing work of the cam receiving plate. SOLUTION: In a tappet for an internal combustion engine in which a cam receiving plate 6 of a cut circle, which has substantially the same diameter as that of a topped cylindrical tappet body 1 and a part of an outer peripheral end is cut, is disposed at the upper surface of the tappet body 1 by slidably fitting a guide groove 5 and a projection 7 to each other which are formed at the contact surface between the lower surface of the cam receiving plate 6 and the upper surface of the tappet body 1 and are oriented in the radial direction. Furthermore, an auxiliary receiving plate 8 formed into the same shape as the cut circle of the cam receiving plate 6 is detachably attached to the upper surface of the tappet body 1 via a small flat head screw 10.

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 that facilitates attachment and detachment of a cam receiving plate on an upper surface of a tappet body.

[0002]

2. Description of the Related Art As a conventional tappet of this type, FIG.
As shown in the figure, a cam is inserted into a concave hole (1a) on the upper surface of a tappet body (1) made of an aluminum alloy having a cylindrical shape with a top.
A hard metal shim (3) with which (2) is in sliding contact is detachably fitted, or as shown in FIG. 7, a small-diameter projection formed on the upper portion of an aluminum alloy tappet body (1). 1b)
There is a cap-shaped hard cam receiving plate (4) which is detachably fitted on the upper surface.

[0003]

The above-mentioned shim (3)
In the tappet provided with the cam and the cam receiving plate (4), it is necessary to replace the shim and the cam receiving plate when they are worn or when the valve clearance is adjusted.

[0004] In the former tappet, the upper surface of the peripheral wall (1c) holding the shim (3) is pressed by using a special tool, whereby the tappet is pushed down, and the shim (3) is moved to the cam (2).
, The shim (3) can be removed from above and replaced without removing the camshaft.

[0005] However, the effective surface area of the upper surface of the shim (3) where the cam (2) slides is reduced by the formation of the peripheral wall (1c). Therefore, in order to increase the lift amount of the engine valve, it is necessary to increase the outer diameter of the tappet body (1) and attach a shim (3) having a large diameter, which limits the degree of freedom in engine design.

In the latter tappet, the cam receiving plate (4) is externally fitted to the small-diameter projection (1b) on the upper portion of the tappet body (1), so that the effective surface area does not decrease as described above. . However, when replacing the cam receiving plate (4), since there is no portion for pressing the tappet body (1), it is necessary to remove the cam shaft and pull out the cam receiving plate (4), which is very difficult. It is troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and prevents the effective surface area of a surface of a cam receiving plate on which a cam comes into sliding contact from becoming small, and facilitates the use of a cam receiving plate. It is an object of the present invention to provide a tappet for an internal combustion engine that can be replaced.

[0008]

According to the present invention, the above-mentioned problem is solved as follows. (1) On the upper surface of a tappet main body having a cylindrical shape having a top, a cam receiving plate having a substantially circular diameter and a part of an outer peripheral end thereof being cut off is provided with a cam receiving plate having a lower surface and an upper surface of the tappet main body. A guide groove formed in the contact surface of the diametrically oriented guide groove and the ridge are slidably fitted to each other by fitting, and an auxiliary receiving plate having the same shape as the missing circular portion of the cam receiving plate is fixed. It is detachably attached to the upper surface of the tappet body by means.

(2) In the above item (1), it is assumed that the fitting portion between the guide groove and the ridge is widened at the fitting back side.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3, as in the conventional case,
Tappet body made of aluminum alloy with a cylindrical shape with a top
On the upper surface of (1), two linear guide grooves (5) (5) parallel to one diameter are formed from one outer peripheral edge to the vicinity of the other outer peripheral edge.

On the upper surface of the tappet body (1), a part of the outer peripheral end of a hard metal disc having the same diameter as the outer diameter of the tappet body (1) is cut into a cut surface parallel to an arbitrary tangent line. A cam receiving plate (6) cut off at (6a) has an outer periphery projecting from its lower surface, orthogonal to the cutting surface (6a) and opposite to the cutting surface (6a) in the radial direction. The guide groove provided near the end
(5) The two ridges (7) and (7), which are complementary to (5), are slidably fitted in the guide grooves (5) and (5) so that they are detachably mounted. ing.

The contact surfaces of the tappet body (1) and the cam receiving plate (6), except for the guide grooves (5) and the ridges (7), are mirror-finished, so that during operation of the engine, The oil film formed on the contact surface enhances the adhesion, and the cam receiving plate
(6) is prevented from floating.

[0013] A crescent-shaped auxiliary receiving plate (8) for making a perfect circular cam receiving surface by supplementing the cut-out portion of the cam receiving plate (6). The countersunk machine screw (10) inserted from above into the through hole (9) drilled at the approximate center of the auxiliary receiving plate (8) is inserted into the female screw hole (11) at a key point on the upper surface of the tappet body (1). The auxiliary receiving plate (8) is detachably fastened to the tappet body (1) by screwing.

As shown in FIG. 2, the boundary between the auxiliary receiving plate (8) and the cam receiving plate (6) is smaller than the rotation locus of the tip of the nose portion (2 a) of the cam (2). The size is set so as to be located on the outside, thereby preventing the boundary portion and the cam (2) from being unevenly worn.

In the tappet of the above embodiment, the cam receiving plate
To remove and replace the cam receiving plate (6) for wear of (6) or adjustment of valve clearance (gap required between the cam and tappet), first remove the cam (2) from its nose. Department
Rotate until the base circle surface excluding (2a) is located on the upper surface of the cam receiving plate (6).

In this state, the cam (2) and the cam receiving plate
Since a slight gap corresponding to the valve clearance is formed between (6) and (6), loosen the countersunk screw (10), remove the auxiliary receiving plate (8), and guide the cam receiving plate (6). It can be easily removed simply by shifting it laterally along the groove (5).

Therefore, as in the prior art, the tappet body (1)
There is no need to press down the camshaft with a special tool or remove the camshaft, and the replacement work of the cam receiving plate (6) can be performed quickly.

FIGS. 4 and 5 show, on an enlarged scale, modifications of the guide groove of the tappet body (1) and the projection on the lower surface of the cam receiving plate (6).

In FIG. 4, one or a plurality of dovetail-shaped guide grooves (12) are formed on the tappet body (1) side, and the guide grooves (12) are formed on the cam receiving plate (6) side. And a ridge (13) forming a complementary shape are slidably fitted.

In FIG. 5, one or a plurality of inverted T-shaped guide grooves (14) whose lower part is widened are formed on the tappet body (1) side, and are appropriately fitted into the guide grooves (14). A ridge (15) that can be slid together is formed on the cam receiving plate (6) side.

In this manner, when the fitting is widened on the inner side, the floating of the cam receiving plate (6) is completely prevented. A gap is formed with the plate (6), and there is no danger of hitting sound or the like.

The present invention is not limited to the above embodiment. In the embodiment shown in FIGS. 1 to 3, the number of the guide grooves (5) and the ridges (7) may be one or two or more.

In each of the above embodiments, the guide groove (5)
(12) and (14) are provided on the tappet body (1) side, and ridges (7), (13) and (15) to be fitted therewith are provided on the cam receiving plate (6), respectively. , Guide grooves (5), (12) and (14)
On the (6) side, ridges (7), (13) and (15) may be provided on the tappet body (1) side, respectively.

The cut surface (6a) of the cam receiving plate (6) may be non-linear.

The present invention can be applied to a case where the tappet body (1) is made of iron.

[0026]

According to the present invention, since the cam receiving plate is provided on the entire upper surface of the tappet body, the effective surface area of the surface on which the cam slides does not become small, so that the diameter of the tappet is minimized. Limit, which increases the degree of freedom in engine design.
Further, since the auxiliary receiving plate can be easily removed simply by removing the auxiliary receiving plate and shifting the cam receiving plate in the radial direction, the replacement operation can be performed quickly.

According to the second aspect, the lifting of the cam receiving plate is prevented, so that there is no danger of hitting sound or the like.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention.

FIG. 2 is a view similar to FIG.
It is an expansion longitudinal front view along a line.

FIG. 3 is an enlarged vertical sectional side view taken along the line III-III of FIG. 1;

FIG. 4 is an enlarged cross-sectional view of a main part showing a modified example of a fitting form of a guide groove of a tappet body and a ridge of a cam receiving plate.

FIG. 5 is an enlarged cross-sectional view of a main part showing another modified example of the fitting form between the guide groove and the ridge.

FIG. 6 is a front view in the center longitudinal section showing a conventional tappet.

FIG. 7 is a front view of a center vertical section showing a conventional example of another tappet.

[Explanation of symbols]

 (1) Tappet body (2) Cam (2a) Nose (5) (12) (14) Guide groove (6) Cam receiving plate (6a) Cut surface (7) (13) (15) Ridge (8) Auxiliary support plate (9) Through hole (10) Flat head screw (fixing means) (11) Female screw hole

Claims (2)

[Claims] An upper surface of a tappet main body having a cylindrical shape with a top is provided with a cam receiving plate having a substantially circular diameter and a part of an outer peripheral end thereof being cut out, and a lower surface and a lower surface of the tappet main body. A guide groove formed in a contact surface with the upper surface and a guide groove facing in the radial direction and a ridge are slidably fitted to each other by fitting, and an auxiliary receiving plate having the same shape as the missing circle portion of the cam receiving plate. A tappet for an internal combustion engine, which is detachably attached to an upper surface of a tappet body by a fixing means. 2. The tappet for an internal combustion engine according to claim 1, wherein the fitting portion between the guide groove and the ridge has a wider width at the fitting inner side.