JPH0589809U - Tappet for internal combustion engine - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] In a tappet for an internal combustion engine, while preventing the strength and rigidity of the shim fitting part from decreasing, the shim can be installed without any special processing on the body or shim. Easily pull out. [Structure] The outer peripheral surface of the shim 3 has an arcuate cross section, and small diameter portions 3a are formed at both upper and lower ends thereof, so that when the shim 3 is fitted in the recess 4 at the upper end of the body 2, the side wall 2b and the shim 3 Since a substantially V-shaped annular recessed groove 6 is formed between the outer peripheral surface of the shim 3 and the contact area between the shim 3 and the side wall 2b, the compressed air blown from the annular recessed groove 6 becomes a bottom surface of the shim 3. Flows in easily and the shim 3 is easily lifted.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tappet used for a direct-acting valve operating mechanism in an internal combustion engine, and more particularly to a tappet that facilitates replacement of a shim for valve clearance adjustment.

[0002]

[Prior Art]

 FIG. 5 schematically shows a direct-acting valve operating mechanism that is widely used in DOHC engines. Therefore, the engine valve (01) includes a pair of cotters (02) (02), a spring retainer (03), It is attached to the cylinder head (05) by a valve spring (04) and the like.

At the upper end of the engine valve (01), there is a cylindrical tappet (06) whose upper surface is closed, and the inner bottom surface of the circular upper wall (07) serves as the stem end of the engine valve (01). It is inserted from above so that it abuts.

A disc-shaped recess (09) is formed inside the annular side wall (08) connected to the upper part of the upper wall (07), and a valve is provided in this recess (09). A clearance adjustment shim (010) is fitted.

In the engine valve (01), the entire tappet (06) guided by the cylinder head (05) is pushed by the rotating cam (011) brought into contact with the upper surface of the shim (010). Can be opened and closed.

In such a direct-acting type valve operating mechanism, when the valve clearance is adjusted, the tappet (06) is pushed downward by an appropriate jig, and the shim (010) having a different thickness is used. However, the shim (010) has a smaller protrusion from the top of the tappet (06), and the gap between the shim (010) and the shim (010) is smaller. It is very difficult to remove it because the upper surface of the upper wall (07) is in close contact with it via the lubricating oil.

To solve this problem, conventionally, tappets as shown in FIGS. 6 and 7 have been proposed. That is, the conventional tappet shown in FIG. 6 has a pair of slotted notches facing each other at an interval of 180 ° in the circumferential direction on an annular side wall (08) continuously provided on the upper part of the upper wall (07). A groove (012) is formed, a driver or the like is inserted into the notch groove (012), and the shim (010) is pulled out.

The tappet shown in FIG. 7 has a small-diameter through hole (013) that extends in the axial direction and is vertically formed at a proper place on the upper surface of the shim (010), and the through hole (013) has a rod-like shape. The shim (010) is pulled out by inserting the removal jig of the above and lifting the shim (010), or by blowing compressed air to raise the shim (010).

[0009]

[Problems to be solved by the device]

 For the purpose of further reducing the weight of valve trains, recent tappets are often made of light alloys such as aluminum alloys in place of the conventional iron such as cast irons. Light alloy tappets are inferior in strength and rigidity to iron ones. Therefore, when the notch groove (012) is formed in the side wall (08) like the conventional tappet shown in Fig. 6 above, when the engine rotates at high speed. In the case where an improper motion is generated in the valve system in Fig. 6 and a large outward cyclic load is applied to the side wall (08), stress is concentrated in the notch groove (012) and cracks occur, or side walls ( 08) may be damaged.

Further, since the notch groove (012) is formed, the number of processing steps is increased and the manufacturing cost is increased. On the other hand, in the latter tappet shown in FIG. 7, since it is necessary to form the through hole (013) in the shim (010), the processing steps are increased and the cost is disadvantageous as in the above case.

The present invention has been made to solve the above-mentioned problems, and prevents the strength and rigidity of the shim fitting portion from being reduced, and specially processes the body and the shim of the tappet body. The purpose of the present invention is to provide a tappet for an internal combustion engine in which the shim can be easily removed and the replacement work can be performed quickly.

[0012]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a cylindrical body whose upper surface is closed with an annular side wall upwardly connected to the upper end of the body, and a valve clearance adjustment is provided in a recess surrounded by the side wall. A small-diameter portion is formed on a tappet formed by detachably fitting a shim for use at least on the outer peripheral surface of the shim by gradually reducing the outer diameter of the shim toward the upper end. Is characterized by. Preferably, the small-diameter portion is formed at both upper and lower end portions of the outer circumference of the shim by making the outer circumferential surface of the shim into an arcuate cross section.

[0013]

[Action]

 By forming a small diameter part that gradually decreases in diameter toward the upper end at least at the upper end of the outer peripheral surface of the shim, the inner peripheral surface of the side wall and the outer peripheral surface of the shim are fitted when the shim is fitted in the recess at the upper end of the body. Since a V-shaped annular groove is formed between the and, and the contact area between the shim and the side wall is small, the compressed air blown from the annular groove easily flows into the bottom surface of the shim, and the shim Easily float up.

[0014]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the present invention, in which a tappet (1) is a cylindrical body (2) formed of a light alloy such as an aluminum alloy, gray cast iron and chrome. It consists of a disc-shaped shim (3) formed of a wear-resistant metal material such as molybdenum steel, and the shim (3) is arranged continuously upwards around the upper end of the upper wall (2a) of the body (2). It is removably fitted in the recess (4) surrounded by the side wall (2b).

The outer peripheral surface of the shim (3) is a curved surface having an arcuate section centered on a line that divides the plate thickness of the shim (3) into two equal parts. The part (3a) is formed. The maximum outer diameter portion at the center of the outer periphery of the shim (3) is in point contact with the inner peripheral surface of the side wall (2b) in the recess (4).

An annular relief groove (5) for polishing the upper surface of the upper wall (2a) is formed at a continuous corner of the side wall (2b) in the recess (4).

As in the first embodiment, when the outer peripheral surface of the shim (3) is a curved surface and the small diameter portion (3a) is formed in the upper and lower portions, the inner peripheral surface of the side wall (2b) and the shim (3) are formed. An annular groove 6 having a substantially V shape is formed between the outer peripheral surface and the outer peripheral surface. When compressed air is blown into the groove (6) by the air gun (A) shown in FIG. 1, the side wall (2b) and the outer periphery of the shim (3) are in point contact with each other. The air that has passed through the pre-formed gap penetrates the oil film and easily flows into the contact surface between the upper wall (2a) and the shim (3), so that the shim (3) is lifted.

Therefore, the shim (3) can be easily pulled out from the recess (4), and the replacement work of the shim (3) can be performed quickly. In addition, since it is not necessary to provide a notch groove or a through hole for taking out the shim in the body (2) or the shim (3) as in the conventional case, the shim (3) can be manufactured at once by a normal molding process or the like. The cost can be reduced.

Further, since the small diameter portion (3a) on the lower side of the shim (3) guides when the shim (3) is fitted in the recess (4), the insertion becomes easy. FIG. 3 shows a second embodiment of the present invention. In this embodiment, the outer diameter of the shim (3) is gradually tapered toward the upper end and the lower end to reduce the small diameter portion (3a). ) (3 a) is formed.

Also in this embodiment, the V-shaped annular groove (6) similar to that described above is formed, and the contact area between the shim (3) and the side wall (2b) is reduced, so that the compressed air is compressed by the shim (6). The shim (3) can easily be pulled out because it easily flows into the lower surface of 3).

FIG. 4 shows a third embodiment of the present invention, in which only the upper half of the shim (3) has an arcuate section (or taper section) to form a small diameter section (3a). The V-shaped annular groove (6) is formed only on the upper side.

Also in this embodiment, since the contact area between the shim (3) and the side wall (2b) is smaller than that of a normal tappet, compressed air can easily flow in and the shim (3) can be easily removed. it can.

[0023]

[Effect of the device]

 According to the present invention, the following effects can be obtained. (a) The shims can be easily lifted by blowing compressed air from the V-shaped annular groove, and the replacement work can be performed quickly, so there is no need to perform special processing on the body or shims. Therefore, the manufacturing process can be simplified and the cost can be reduced. (b) Since it is not necessary to cut out the side wall as in the conventional case, the strength and rigidity of the shim fitting portion will not be reduced even if the body is molded of aluminum alloy or the like. (c) If small-diameter parts are formed at the upper and lower ends of the outer periphery of the shim, compressed air will more easily flow into the bottom surface of the shim, and it will guide the shim when it is fitted into the recess. Become.

[Brief description of drawings]

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

FIG. 2 is an exploded perspective view of the same.

FIG. 3 is a half sectional view showing a second embodiment of the present invention.

FIG. 4 is a half sectional view showing a third embodiment of the same.

FIG. 5 is a central vertical sectional front view schematically showing a direct acting type valve operating mechanism to which the present invention is applied.

FIG. 6 is an exploded perspective view showing a conventional tappet.

FIG. 7 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 (3a) Small diameter part (4) Recess (5) Escape groove (6) Annular groove (A) Air gun

Claims (2)

[Scope of utility model registration request] 1. A ring-shaped side wall is continuously provided upwardly on an upper end portion of a cylindrical body whose upper surface is closed, and a shim for adjusting a valve clearance is detachable in a recess surrounded by the side wall. In the tappet formed by fitting, a small diameter portion is formed at least at an upper end portion of an outer peripheral surface of the shim by gradually reducing an outer diameter of the shim toward an upper end. 2. The tappet for an internal combustion engine according to claim 1, wherein the small-diameter portion is formed at both upper and lower end portions of the outer periphery of the shim by making the outer peripheral surface of the shim into an arcuate cross section.