JPH06114470A - Tip fitting method for internal combustion engine tappet - Google Patents

Abstract

PURPOSE:To rigidly fix a tip in an engaging hole by rising the calking force applied on the tip provided at the contacting part with an engine valve in the inner bottom of a tappet main body. CONSTITUTION:A gentle curving part 5a is formed on the lower peripheral end edge of the tip 5, the inner bottom face around the curving part is plastic deformed 8 by pressurizing with a punch having a calking blade and, accordingly, the engaging area of the plastic deformed part 8 and the tip 5 is extended and when the plastic deforming 8 is exerted, the pressurizing load is orthogonally and effectively applied on whole or a part of the curving part 5a. Thus, since the calking force on the tip 5 is risen, the tip 5 is rigidly fixed in the engaging hole 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of attaching a tip of a tappet for an internal combustion engine, in which a tip provided on an inner bottom surface of a tappet body for contacting an engine valve is firmly fixed.

[0002]

2. Description of the Related Art In recent years, attempts have been made to further improve engine performance by using an aluminum alloy tappet (valve lifter) for a direct-acting type valve operating mechanism such as a DOHC type to reduce the weight of the valve operating system.

Since aluminum alloy tappets have lower strength and rigidity and are inferior in wear resistance to those made of normal iron, wear resistant metal materials are attached to the contact surfaces with rotating cams and engine valves. used.

FIG. 4 shows a tappet made of an aluminum alloy incorporated in a direct-acting valve operating mechanism, in which (101) is a cylinder head and (102) is slidably fitted in the cylinder head (101). The tappet body has a cylindrical shape with its upper surface closed, and has a large-diameter recess (102a) formed on the upper surface of its upper wall (102a).
In b), there is a disc-shaped shim (103) made of wear-resistant metal material that comes into contact with the rotating cam (105), and a bottomed fitting hole formed in the center of the inner bottom surface of the upper wall (102a). (102c) has an engine valve
Small-diameter chips (104), which are also made of a wear-resistant metal material, and which are in contact with the shaft end of (106), are fitted in each.

When fixing the chip (104) to the fitting hole (102c), the chip (104) may fall off due to the difference in the coefficient of thermal expansion of both members and the like, if merely press-fitted.
As shown in (upside down), the peripheral portion of the fitting hole (102c) in which the chip (104) is fitted is provided with a caulking blade (107) having an inverted triangular cross section at the lower end for caulking. The tip (104) is prevented from falling off by applying strong pressure with the punch (108) and plastically deforming (109) the peripheral edge portion inward (centripetal direction) to caulk.

[0006]

In the above-described conventional method of mounting the tip, since the peripheral edge of the tip (104) is formed at a right angle, the engagement between that portion and the plastic deformation (109) portion ( The contact area is small and the crimping force of the tip (104) is weak.

Further, the tip (10) in the plastic deformation (109) portion is
Since a corner (109a) that sharply bends inward is formed at the contact portion with the upper edge of 4) (referring to FIG. 5), stress tends to concentrate on this portion, which may cause long-term operation of the engine. As a result, the plastic deformation (109) part is settled to weaken the caulking force, or the part is cracked.

If the tip (104) is not firmly fixed in the fitting hole (102c), the tip (104) and the tappet body (102) or between the tip (104) and the engine valve (106). There is a gap between the two, and a striking noise is generated during operation, abnormal wear is caused, etc., and durability and reliability are impaired.

As a means for firmly fixing the tip (104), it is conceivable to increase the pressing load of the punch (108) to increase the caulking force and increase the holding force of the tip (104), but it is more than necessary. When it is caulked with a strong force, as shown in FIG. 5, not only a crack (111) is formed at the top of the concave groove (110), but also a corner (109a) is sharply bent and a crack is also formed in this portion. May occur.

The present invention has been made in order to solve the above-mentioned problems, and by substantially increasing the crimping force of the chip, the chip is firmly fixed in the fitting hole, and the durability and reliability are improved. An object of the present invention is to provide an excellent tappet tip mounting method for an internal combustion engine.

[0011]

In order to achieve the above object, the present invention provides a lower peripheral edge in a fitting hole formed in the center of the inner bottom surface of a cylindrical tappet body having a closed upper end. After fitting a chip having a gently curved surface, the peripheral end of the fitting hole in the inner bottom surface is pressed by a punch having a caulking blade with a substantially triangular cross section to plastically deform inward. It is characterized by tightening.

[0012]

[Function] A gently curved surface is formed on the lower peripheral edge of the chip, and the inner bottom surface around the peripheral surface is pressed by a punch having a caulking blade to be plastically deformed inward, whereby the plastically deformed part and the chip are separated. The engagement area increases, and the pressing load at the time of plastic deformation effectively acts on the entire curved surface or a part of the surface at a right angle. This increases the crimping force of the tip,
The chip is firmly fixed in the fitting hole.

[0013]

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 the center of the thick portion (3) formed in the center of the inner bottom surface of the upper wall (2) of the tappet body (1) made of an aluminum alloy. A bottomed fitting hole (4) that opens downward is formed in this.

The tip (5) is made of a wear resistant metal material.
It is formed in a disk shape having a plate thickness slightly smaller than the depth of the fitting hole (4), and the lower peripheral edge thereof has a radius of curvature in the central portion as shown in an enlarged view in FIG. A gentle curved surface portion (5a) is formed that is relatively large and has a small radius of curvature at both upper and lower ends.

The chip (5) is fixed in the fitting hole (4) by the following procedure. That is, as shown in FIG. 2 with the top and bottom reversed, first, the tip (5) is directed toward the upper side of the curved surface portion (5a) (hereinafter, the up and down direction is referred to as the inverted state of FIG. 2) and is inserted into the fitting hole (4). After fitting, the thick part at the periphery of the fitting hole (4)
The upper surface of (3) is strongly pressed with a punch (6) provided with a circular caulking blade (6a) having an inverted isosceles triangular cross-section whose narrow angle at the intersection of the inner and outer hypotenuse is approximately 90 ° at the lower end.

Then, the caulking blade is attached to the upper surface of the thick portion (3).
An annular groove (7) having an inverted triangular cross section, which is a complement to (6a), is formed, and at the same time, the edge of the thick portion (3) around the fitting hole (4) has a tip (5). ) Is plastically deformed (8) inward along the curved surface (5a), and the tip (5) is caulked. The top of the caulking blade (6a) should be slightly rounded to avoid stress concentration on the top of the groove (7).

When the tip (5) is caulked in this way,
The engagement (contact) area between the plastic deformation (8) part and the tip (5) is significantly increased as compared with the conventional one, and the plastic deformation (8) is applied to the whole or a part of the curved surface part (5a). The pressing load at that time acts at right angles and effectively.

As a result, the holding force for pushing the tip (5) into the fitting hole (4) and the caulking force (tightening force) are increased,
The chip (5) is firmly fixed in the fitting hole (4).

Moreover, unlike the prior art, since the contact portion between the tip (5) and the plastic deformation portion (8) does not have an angle, there is no portion where stress concentrates, and therefore plastic deformation occurs during engine operation.
There is no fear that the portion (8) will be settled or cracked, and the caulking force will be maintained for a long time.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, the inward hypotenuse of the caulking blade (6a) which is on the caulking side is the curved surface portion (5a) of the tip (5). It is formed on a concave curved surface having almost the same curvature as.

When curved in this way, as compared with the first embodiment, the flow of meat in the plastic deformation (8) portion becomes smoother, the amount of plastic deformation inward is increased, and the pressing load is increased. Effectively acts on the entire curved surface portion (5a), so that the caulking force is further increased.

In both of the above embodiments, the tip (5) is crimped in a circular shape. However, a punch having a plurality of discontinuous caulking blades is used to make the tip (5).
You may caulk multiple places around. The shape of the tip (5) is not limited to the disc shape described above, and it goes without saying that it may be an oval shape or an oval shape.

[0023]

According to the present invention, since the pressing load at the time of plastic deformation effectively acts on the gently curved surface formed on the chip, the caulking force of the chip is significantly increased, and the chip is inserted into the fitting hole. Can be firmly fixed to.

If the inside of the caulking blade is a concave curved surface, the amount of plastic deformation increases and the caulking force increases.

[Brief description of drawings]

FIG. 1 is a central vertical sectional front view of a main part of a tappet to which a first embodiment of the present invention is applied.

FIG. 2 is an enlarged cross-sectional view of a main part of the chip, which is also upside down showing the caulking procedure.

FIG. 3 is an enlarged cross-sectional view of a main part showing a caulking procedure of a second embodiment of the present invention.

FIG. 4 is a central vertical sectional front view of a direct-acting valve mechanism and a tappet according to a conventional method incorporated therein.

FIG. 5 is a vertical sectional front view of a main part showing a caulking procedure of a conventional chip.

[Explanation of symbols]

(1) Tappet body (2) Upper wall (3) Thick wall (4) Fitting hole (5) Tip (5a) Curved surface (6) Punch (6a) Caulking blade (7) Recessed groove (8) Plastic deformation

Claims (2)

[Claims] 1. A tip having a curved surface portion at a lower peripheral edge is fitted into a fitting hole formed in a center of an inner bottom surface of a tappet body having a closed upper end, and the inner bottom surface is then fitted. A method for attaching a tippet of a tappet for an internal combustion engine, characterized in that the peripheral end portion of the fitting hole is pressed by a punch having a caulking blade having a substantially triangular cross section to be plastically deformed inward, thereby caulking. 2. The method of mounting a tappet for an internal combustion engine according to claim 1, wherein an inner side of the caulking blade is formed as a concave curved surface having substantially the same curvature as that of the curved surface of the chip.