JP3203495B2 - Tip mounting method for tappets for internal combustion engines - Google Patents

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 made of a wear-resistant metal material to a contact portion of a tappet used in a direct-acting valve train of an internal combustion engine with an engine valve.

[0002]

2. Description of the Related Art Recently, there has been a tendency to adopt a DOHC type valve operating mechanism due to a demand for high rotation and high output of an engine.
In addition, tappets (valve lifters) used in the valve train tend to be made of aluminum alloys instead of conventional irons for the purpose of further reducing the weight of the valve train.

[0003] Tappets made of aluminum alloy have lower strength and rigidity than iron, and are inferior in wear resistance. Therefore, in general, a wear-resistant metal material is used for the contact surface between the rotating cam and the shaft end of the engine valve. They are used by attaching them.

FIG. 5 shows a conventional tappet incorporated in a direct-acting type valve operating mechanism, wherein (101) is a cylinder head, and (102) is a tappet slidably fitted to the cylinder head (101). The main body has a cylindrical shape with a closed upper surface, and a large-diameter recess (102a) formed at the upper end surface has a disk-shaped shim (103) made of a wear-resistant metal material. A small-diameter disc-shaped chip (104) made of a wear-resistant metal material is fitted into the fitting hole (102b) formed on the bottom surface.

[0005] The lower end surface of the chip (104) has a pair of cotters (10
5) (105), spring retainer (106), valve spring
The shaft end of the engine valve (108) attached to the cylinder head (101) is abutted by (107) and the like. Sim (10
The upper end surface of 3) is in sliding contact with a rotary cam (109) disposed substantially on the axis of the engine valve (108).

The tip (10) is inserted into the fitting hole (102b) of the tappet (102).
Conventionally, 4) is fixed by means as shown in FIG. In FIG. 6, the tappet (102) is shown in an upside-down posture in FIG. 5 to show the state at the time of processing.

With the inner bottom surface of the tappet (102) facing upward,
A disk-shaped tip (104) of a wear-resistant metal material is fitted into the fitting hole (102b), and a punch (11) for caulking (caulking) is formed.
In 1), the periphery of the fitting hole (102b) is pressed.

On the lower surface of the punch (111), a caulking blade (112) having a triangular cross-section is projected downward along a circumference having a diameter larger than the diameter of the fitting hole (102b). Yes, by pressing the caulking blade (112) against the inner bottom surface of the tappet (102), the periphery of the fitting hole (102b) is plastically deformed inward.
(The periphery after plastic deformation is shown in FIG.
The chip (104) is fixed.

[0009]

In the above-mentioned conventional means, the engagement area between the peripheral edge (110) of the fitting hole (102b) and the peripheral edge of the upper surface (the upper surface in FIG. 6) of the chip (104) is reduced. Since it is small and the amount of deformation that bends inward from the outer edge of the tip (104) is relatively small, there is a problem that the holding and fixing of the tip (104) are likely to be incomplete.

If the tip (104) is not sufficiently fixed, a gap is formed between the tip (104) and the tappet (102) or between the tip (104) and the engine valve (108).
A striking noise is generated during operation and causes abnormal wear. Further, if the valve train causes irregular movement due to a surging phenomenon or the like, in the worst case, the chip (104) may fall off.

In order to firmly fix the chip (104),
The caulking blade (112) of the punch (111) may be formed in a large size, and a large pressing force may be applied to increase the amount of plastic deformation of the peripheral portion (110) of the fitting hole (102b). , This way,
Crack (113) at the top of the bottom of triangular cross-sectional groove (hereinafter referred to as caulking groove) formed on the inner bottom surface of tappet (102)
And sufficient holding power cannot be obtained.

Further, the caulking blade (112) of the conventional punch (111) is, for example, a bottom view of the punch shown in FIG.
Are formed in a plurality of circular arcs, and are arranged along a required circumference. In this case, six caulking blades (112) each having an arc shape having a circumferential angle of 40 degrees are set to 2
They are arranged at intervals of 0 degrees.

In this case, since both end surfaces of each caulking blade (112) are radial surfaces, the intersection with the arc-shaped side surface becomes a right angle, and the caulking groove formed on the tappet (102) is formed. Also has a correspondingly sharp reentrant angle, which tends to cause cracks in this portion.

An object of the present invention is to provide a method for mounting a tip of an internal combustion engine tappet, which solves the above-mentioned problems in the conventional means.

[0015]

In order to achieve the above object, the present invention provides an internal combustion engine for fixing a chip in a fitting hole formed in the center of the inner bottom surface of a cylindrical tappet having a closed upper surface. In the method of attaching a tappet for a chip, a chamfered portion is formed around the entire peripheral edge of the tip on the opening side of the fitting hole, and the periphery of the fitting hole is pressed with a punch having a caulking blade, so that the fitting hole is formed. Is plastically deformed inwardly so that the peripheral edge of the edge portion comes into close contact with the slope of the chamfered portion.

[0016] The co Kingu groove may be formed into a circular diameter larger than the diameter of the fitting hole (4).

A plurality of caulking concave grooves are formed in an arc shape, and are arranged in a row along a circumference having a diameter larger than the diameter of the fitting hole, and both ends of each caulking blade are connected to an arc-shaped portion in a semicircle. Alternatively, it may be formed by a curve such as a semi-ellipse.

[0018]

[Action] A chamfer is formed at the peripheral edge of the chip, and the
By plastically deforming the periphery along the chamfer,
The area of engagement between the edge portion and the chip is increased, the holding force of the chip is enhanced, and the occurrence of loosening during use is prevented.

[0019]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is an enlarged partial sectional view showing a main part of FIG.

A tappet (1) made of an aluminum alloy has a cylindrical shape in which the lower surface in FIG. A fitting hole (4) for fitting a chip (5) is provided at the center of the thick portion (3) formed in the above.

The tip (5) is formed of a wear-resistant metal material in the shape of a disk, and is provided with a chamfer (5a) in which the peripheral edge is cut off obliquely.

The inner wall of the fitting hole (4) of the tappet (1) is formed as shown in FIG. 2 so that the tip (5) can be fitted into the fitting hole (4) until the caulking process in the next step is performed. It is formed in the shape of a right cylinder indicated by a chain line.

After the chip (5) is fitted in the fitting hole (4), the caulking blade is connected to the fitting hole (4) using a punch similar to that shown in FIG.
When pressed against the outer surface of the thick portion (3), a caulking groove (6) having a triangular cross section is formed on the upper surface of the thick portion (3), and the peripheral edge of the inner wall of the fitting hole (4) is formed. The part (7) is plastically deformed inward.

At this time, since the chamfered portion (5a) is provided on the peripheral edge of the upper surface of the chip (5), the peripheral edge portion (7) is
Plastically formed in close contact with the slope.

Therefore, compared with the conventional method in which the chamfered portion (5a) is not provided, the engaging area between the peripheral portion (7) and the chip (5) is increased, so that the pressing force by the caulking blade is relatively small. Even if it is small, a strong holding force is generated, and the chip (5) can be stably held.

FIGS. 3 and 4 are plan views of the chip fitting portion after being formed by pressing with a caulking blade.

FIG. 3 shows a thick part (3) of a tappet (1) using a punch having a continuous circular caulking blade.
The caulking concave groove (61) formed in a circular shape is formed continuously over the entire circumference. In this case, since there are no corners where cracks are likely to occur, the occurrence of cracks during pressing can be almost completely prevented.

Further, since the peripheral edge (7) of the fitting hole (4) deformed along the chamfered portion (5a) of the chip (5) is formed uniformly over the entire peripheral edge of the chip (5). The tip (5) can be held sufficiently firmly.

FIG. 4 shows a case where a plurality of arc-shaped caulking grooves (62) are formed by using a punch having a plurality of arc-shaped caulking blades arranged along the circumference, and each caulking groove is formed. The groove ends (63) at both ends of the groove (62) are formed into a curve such as a semicircle, a circular arc, or a semi-ellipse continuous with the arc-shaped portion. Also in this case, since there is no sharp reentrant angle as in the conventional example of FIG. 7, it is possible to prevent the occurrence of cracks during pressing.

Further, in the case of FIG.
The pressing force is the full circular caulking groove (61) in FIG.Form
IfLess than the fitting hole (4)Perimeter
The pressing means for performing the pressing to deform (7) as required
It can be a lightweight type.

In the above embodiment, the chamfered portion (5a) formed on the chip (5) is machined on both sides of the chip (5), but at least faces the opening side of the fitting hole (4). It goes without saying that the present invention can be implemented as long as the chamfered portion (5a) is provided on one side.

However, if the chamfered portion (5a) is provided only on one side, it is troublesome when the chip (5) is fitted into the fitting hole (4), or the surface provided with the chamfered portion (5a) is fitted. Since it is necessary to mount the chip (5) toward the opening side of the hole (4), it is troublesome to determine the front and back of the chip (5). Therefore, it is convenient in actual work to provide chamfers (5a) on both sides of the chip (5) as in the above-described embodiment.

[0033]

According to the present invention, the following effects can be obtained. (a) The chamfered portion is formed in the peripheral edge of the chip, by plastically deforming the peripheral edge of the fitting hole inwardly along the chamfered portion, the engagement between the peripheral edge of the peripheral portion and the chip The area is increased, and the chip can be stably held.

(B) Since the engaging area between the peripheral portion and the chip is large, a sufficient holding force can be obtained by a relatively small caulking pressure, and the tappet does not crack due to excessive pressurization.

(C) By forming the shape of the coking groove into a continuous circle or a plurality of arcs, and forming both ends of the arc into a curve continuous with the arc-shaped portion, the shape of the chip fitting portion is reduced. Cracks can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG.

FIG. 3 is a plan view of a chip fitting portion showing an example of caulking in the present invention.

FIG. 4 is a plan view of a chip fitting portion showing another coking example.

FIG. 5 is a longitudinal sectional view showing a configuration of a tappet incorporated in a direct-acting type valve train.

FIG. 6 is a longitudinal sectional view of a main part showing a caulking means for fixing a chip to a conventional tappet.

FIG. 7 is a bottom view of a punch used for forming a conventional caulking groove.

[Explanation of symbols]

(1) Tappet (2) Head wall (3) Thick wall (4) Fitting hole (5) Chip (5a) Chamfer (6) Caulking groove (7) Peripheral edge (61) Full circular caulking groove ( 62) Arc-shaped caulking groove (63) End of groove

Claims (3)

(57) [Claims] 1. A method for mounting a tappet for an internal combustion engine in which a tip is fixed in a fitting hole formed at the center of an inner bottom surface of a cylindrical tappet having a closed upper surface, the method comprising: A chamfered portion is formed around the entire peripheral edge, and the periphery of the fitting hole is pressed with a punch having a caulking blade so that the peripheral portion of the fitting hole is inwardly in close contact with the slope of the chamfered portion. A tip mounting method for a tappet for an internal combustion engine, wherein the tip is plastically deformed. 2. A continuous circle extending over the entire circumference of the caulking groove.
2. The method according to claim 1, wherein the tappet is formed in a shape . 3. A caulking groove is formed in a plurality of arcs and arranged in a row along a circumference having a diameter larger than the diameter of a fitting hole, and both ends of each caulking groove are connected to an arc-shaped portion. 3. The method according to claim 1, wherein the tip is formed by a curved line such as a semicircle, an arc, or a semiellipse.