JP2536695Y2 - Tappet for internal combustion engine - Google Patents

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, and more particularly to a tappet that facilitates replacement of shims for adjusting valve clearance.

[0002]

2. Description of the Related Art FIG. 4 schematically shows a direct-acting type valve operating mechanism frequently used in a DOHC type engine. An engine valve (01) includes a pair of cotters (02) and (02) and a spring. Cylinder head by retainer (03), valve spring (04), etc.
(05).

[0003] At the upper end of the engine valve (01), a cylindrical tappet (06) having a closed upper surface has an inner bottom surface of the circular upper wall (07) and a stem end of the engine valve (01). It is fitted from above so as to abut.

An annular side wall (0) connected to the upper part of the upper wall (07)
8), a dish-shaped recess (09) is formed inside the recess.
(09) is fitted with a shim (010) for adjusting the valve clearance.

The engine valve (01) has a cylinder head (0)
The entire tappet (06) guided by 5) is opened and closed by being pushed by the rotating cam (011) brought into contact with the upper surface of the shim (010).

[0006] In such a direct acting type valve operating mechanism, when adjusting the valve clearance, the tappet (06) is pushed down by an appropriate jig and the shim (010) having a different thickness is used. It is done by exchanging, but sim
The protrusion of the tappet (06) from the upper end of the (010) is small, the clearance of the fitting portion of the shim (010) is small, and the
0) and the upper surface of the upper wall (07) are in close contact with each other via the lubricating oil, and it is very difficult to remove them.

To solve this problem, tappets as shown in FIGS. 5 and 6 have been conventionally proposed. That is, in the conventional tappet shown in FIG. 5, a pair of slit-shaped notches opposed to each other at an interval of 180 ° in the circumferential direction are formed on an annular side wall (08) continuously provided above the upper wall (07). A groove (012) is formed, a screwdriver or the like is inserted into the cutout groove (012), and the shim (010) is extracted.

The tappet shown in FIG. 6 has a shim (010)
In a suitable place on the upper surface, a small-diameter through-hole (013) facing in the axial direction is vertically penetrated, and a rod-shaped extraction jig is inserted into this through-hole (013) to lift the shim (010), Alternatively, the shim (010) is drawn out by blowing compressed air through the through hole (013) to lift up the shim (010).

[0009]

In recent tappets, in order to further reduce the weight of the valve train, many tappets are made of a light alloy such as an aluminum alloy instead of the conventional iron such as a cast iron. Since the tappet made of light alloy is inferior in strength and rigidity to that of iron, if the cutout groove (012) is formed in the side wall (08) as in the conventional tappet shown in FIG. In the event that an improper movement occurs in the valve operating system and a large outward repetitive load acts on the side wall (08), stress concentrates on the notch groove (012) and a crack occurs or the side wall (08) is It may be damaged.

On the other hand, the latter tappet shown in FIG.
Not only does it require a step of drilling a through hole (013) for removing the shim (010), but also the shim (010)
If it is in close contact with (07) in a vacuum, the removal jig inserted into the through-hole (013) will slip and it will take time to remove the shim (010), or simply blow compressed air into the through-hole (013). Simply, the shim (010) may not come up.

The shim (010) is designed to be rotated in a certain direction by a force acting upon rotation of the rotary cam (011) and orthogonal to the axis. When the perforated portion of the through hole (013) comes into contact with the nose surface of the rotating cam (011), the shim (010)
And the rotating cam (011) intermittently change the surface pressure of the sliding contact surface thereof, and the surface pressure becomes higher than the surroundings.

As a result, localized uneven wear may occur on the upper surface of the shim (010) around the through hole (013) and on the nose surface of the rotating cam (011), thereby impairing durability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and reduces the strength and rigidity of a shim fitting portion, and causes uneven wear on the sliding surfaces of a shim and a rotating cam. It is an object of the present invention to provide a tappet for an internal combustion engine in which a shim can be easily pulled out without any trouble.

[0014]

In order to achieve the above object, the present invention provides an annular side wall which is connected to the upper end of a cylindrical body whose upper surface is closed, and which is surrounded by the side wall. In the tappet, a shim for adjusting valve clearance is detachably fitted in the recessed portion, a concave groove of a required length is formed on the upper surface of the body, one end of which extends to a continuous corner portion of the side wall, An elastic push-up rod having a substantially central portion curved upwardly is fixed in the concave groove at one end of the push-up rod at an appropriate position of the body in the concave groove, and the other end is formed on the side wall or the body. And is housed so as to be located in a guide hole communicating with one end of the concave groove and the outside.

[0015]

A push-up rod having a substantially central portion curved upwardly in a concave groove formed on an upper surface of a body, and one end of which is located in a guide hole communicating with the concave groove formed in the side wall or the body. By inserting an appropriate tool from the guide hole and strongly pressing one end of the push-up bar, the central part of the push-up bar is elastically deformed like a bow, and the lower surface of the shim is forcibly pushed up. The shim can be easily removed from the recess.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 and 2, a tappet (1) is a cylindrical body (2) formed of an aluminum alloy or the like.
And a disk-shaped shim (3) formed of a wear-resistant metal material such as gray cast iron or chromium molybdenum steel. The shim (3) is provided around the upper end of the upper wall (2a) of the body (2). It is detachably fitted into a recess (4) surrounded by a side wall (2b) provided continuously upward.

On the upper surface of the upper wall (2a), a concave groove (5) which faces in a diametrical direction perpendicular to the central axis of the body (2) and has a convex portion (5a) at the center of the bottom surface is formed on the side wall (2). It is formed up to the continuous corner of 2b).

A part of the side wall (2b) extends substantially downward from the upper end, draws a gentle arc from the middle, and the lower end is connected to one end side (the right end side in FIG. 1) of the concave groove (5). A communicating circular guide hole (6) is provided.

A resilient push-up bar 7 having a relatively small diameter, such as a piano wire, an oil-tempered wire, a stainless steel wire, or the like, is inserted into one end (left end in FIG. 1) of the groove 5. )
Into the guide hole (6) while being fitted into a locking hole (8) formed in the peripheral end of the upper wall (2a) continuous with the concave groove (5). By doing so, it is housed so that it can come and go freely.

At the time of this storage, the push-up bar (7)
Is curved slightly upward by contacting the central part with the convex part (5a), and the upper end of the central part is the upper wall (2a).
The upper surface of the shim (3) is located at a level substantially equal to or slightly lower than the upper surface, so as not to interfere with the lower surface of the shim (3).

When removing the shim (3) from the recess (4), first, as shown in FIG. 3, the entire tappet (1) is pushed down by an appropriate jig, and a required amount of the tappet (1) is interposed between the tappet (1) and the rotating cam (C). After forming the gap, insert the tool (9) with a small tip at the guide hole (6).
And press the upper end of the push-up bar 7 downward. Then, since the push-up bar (7) is previously bent upward by the convex portion (5a), it is forcibly elastically deformed like a bow as shown by the solid line in FIG. The lower surface of (3) is pushed up, so the shim (3) rises easily

Therefore, the shim (3) is moved through the upper wall (2) through the lubricating oil.
Even if it is in close contact with a), it can be easily removed from the recess (4), and the replacement work of the shim (3) can be performed quickly.

As described above, in the above-described embodiment, the shim (3) can be easily removed simply by pressing downward the end of the push-up bar (7) inserted into the side wall (2b). Since it is possible, there is no need to form a through hole in the shim (3) as in the related art. Accordingly, not only the step of forming a through hole in the shim (3) is omitted, but also the surface pressure of the sliding contact surface between the shim (3) and the rotary cam (C) changes intermittently. There is no danger that the surface pressure will increase locally, and the shim (3) and rotating cam (C)
There is no uneven wear on the sliding surfaces.

Further, since it is not necessary to cut off a part of the side wall (2b) as in the prior art, the strength and rigidity of the shim fitting portion are reduced even if the body (2) is formed of an aluminum alloy or the like. There is no. Note that the present invention is not limited to the above embodiment, but can take various forms.

For example, in the above embodiment, one end of the push-up bar (7) is inserted into an upward guide hole (6) formed in the side wall (2b),
Although the upper end of the push-up bar (7) is pressed downward,
As shown by the imaginary line in FIG. 1, the concave groove in the body (2)
In the extension direction of (5), the groove (5) and the lateral hole (1
0), and insert one end (right end) of the push-up bar (7) into the lateral hole (10) so that the push-up bar (7) is strongly pressed laterally by the tool (9). You may.

Although not shown, a part of the side wall (2b) is cut out, and a pressing piece that forms a part of the side wall (2b) is fitted into the notch so as to be movable up and down. The upper end of the push-up bar (1) facing upward may be press-fitted into the lower end of the push-up bar.

In this way, the push-up bar is directly
There is no need to press the end of (7), and the pressing surface is widened, so that the shim (3) can be easily removed without using a special tool.

If the central portion of the push-up bar (7) is previously processed so as to be slightly upwardly curved in the concave groove (5),
The protrusion (5a) may be omitted. The material of the push-up bar 7 may be a hard and elastic synthetic resin material.

[0029]

According to the present invention, the following effects can be obtained. (a) Since the shim can be easily and reliably extracted only by forcibly pressing one end of the push-up bar, it is not necessary to form a through hole in the shim as in the related art, and the processing process is simplified. (b) In addition, since the upper surface of the shim is a flat surface, there is no danger of uneven wear or the like occurring on the sliding surfaces of the shim and the rotating cam. (c) Since there is no need to cut out the side wall as in the conventional case, the strength and rigidity of the shim fitting portion do not decrease even if the body is formed of an aluminum alloy or the like.

[Brief description of the drawings]

FIG. 1 is a front view of a central longitudinal section showing an embodiment of the present invention.

FIG. 2 is a central longitudinal side view of a main part along the line AA in FIG. 1;

FIG. 3 is an explanatory view showing a procedure for removing a shim.

FIG. 4 is a central longitudinal sectional front view schematically showing a direct-acting type valve operating mechanism to which the present invention is applied.

FIG. 5 is an exploded perspective view of a conventional tappet.

FIG. 6 is an exploded perspective view showing another example of the conventional tappet.

[Explanation of symbols]

(1) Tappet (2) Body (2a) Upper wall (2b) Side wall (3) Shim (4) Concave (5) Concave groove (5a) Convex part (6) Guide hole (7) Push rod (8) Bore (9) Tool (10) Guide hole (C) Rotating cam

Claims (1)

(57) [Scope of request for utility model registration] 1. An annular side wall is provided upwardly at the upper end of a cylindrical body having a closed upper surface, and a shim for adjusting valve clearance is detachable in a recess surrounded by the side wall. In the fitted tappet, a concave groove of a required length is formed on the upper surface of the body at one end side to a continuous corner of the side wall, and a substantially central portion is curved upward in the concave groove. One end of the push-up rod having elasticity is fixed to an appropriate position of the body in the groove, and the other end communicates with one end of the groove and the outside, which is formed in the side wall or the body. A tappet for an internal combustion engine, which is housed so as to be located in a guide hole.