JP2000337111A - Tappet for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To re-use a shim by a method wherein the shim of a tappet for an internal combustion engine is brought into a state to be easily exchanged and inside is turned out when one surface of the shim is worn out. SOLUTION: A tappet 10 is provided with a cylindrical tappet body 13 having a top wall 12, and a shim 16. The shim 16 is removably situated in a containing recessed part 15 surrounded by a peripheral wall 14 formed in a manner to protrude to the outside of the outer peripheral part of a top wall 12. A tool engaging groove 17 brought into partial communication externally of the end face of a peripheral wall 14 is formed in the central part in the direction of the thickness of the outer peripheral surface of the shim 16. Cam contact surfaces 19a and 19b are formed on both surfaces of a surface and a back and the surface and the back are formed in a shape symmetrical with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tappet having a tappet body and a shim detachably mounted on the tappet body and used for a direct-acting valve train in an internal combustion engine.

[0002]

2. Description of the Related Art As a valve train for controlling gas exchange by operating an intake valve and an exhaust valve of an engine, an OHC type having a cylinder head and respective valves is generally used. As this type of valve operating mechanism, a direct acting type in which a valve is directly driven by a camshaft is frequently used. In this type, a lifter or a tappet is attached to a rear end of the valve. .

A tappet has a cylindrical portion and a top wall provided at one end thereof, and comprises a tappet body having a cup-shaped cross section, and a valve clearance adjusting shim disposed on the outer surface of the top wall. The shim is detachably disposed in a housing recess surrounded by a peripheral wall formed to protrude outward from an outer peripheral portion of a top wall of the tappet body. The cam comes into sliding contact with the outer surface of the shim, and when the shim wears, the cam is replaced with a new one, or when the engine is assembled, the shim is replaced with a shim having a different thickness according to the clearance of the valve.

[0004]

In order to easily replace the shim, a service groove or notch is formed in the peripheral wall on the top side of the tappet body, and the tool is used to remove the shim when removing the shim. There is one that penetrates and pushes out the shim, but if you form a groove etc. in the tappet body,
The strength of the tappet body will be reduced. On the other hand, there is a case in which a through hole is formed in the shim, and a tool is inserted into the through hole to remove the shim.In this case, the contact area between the cam and the shim is reduced. The amount of wear will increase.

Therefore, the outer peripheral surface of the shim is formed to protrude in an arc shape so that the protruding portion is in line contact with the inner peripheral surface of the peripheral wall, thereby forming a groove in the tappet body or forming a through hole in the shim. There is a tappet in which compressed air is blown between the outer peripheral surface of the shim and the inner surface of the peripheral wall of the tappet body to remove the shim (see Japanese Utility Model Registration No. 2550222). However, if the outer periphery of the shim is protruded so as to make line contact with the peripheral wall, abrasion occurs, and there is a problem that durability cannot be improved.

Further, as shown in Japanese Utility Model Publication No. 2-12243, an annular groove is formed on the outer peripheral surface of the shim, and a gripping tool having a forked arc-shaped portion which is fitted into the annular groove and sandwiches the shim is used. There is one that removes the shim. However, in this case, the gripping tool must be inserted from the side in the direction along the surface of the shim, which requires a large space for replacement work. The annular groove must then be offset towards the front side of the shim. For this reason, the front and back sides of the shim are asymmetric, and it is necessary to check the front and back sides of the shim when attaching the shim.

An object of the present invention is to make it possible to easily change the shim of a tappet for an internal combustion engine.

It is another object of the present invention to enable the shim to be used upside down when one side of the shim is worn.

[0009]

According to the present invention, there is provided a tappet for an internal combustion engine, comprising a cylindrical tappet body having a top wall, and a housing recess surrounded by a peripheral wall formed to protrude outward on an outer peripheral portion of the top wall. A disk-shaped shim for valve clearance adjustment removably disposed in the internal combustion engine tappet, at the center in the thickness direction of the outer peripheral surface of the shim,
A tool engagement groove is formed by communicating a part outward from the end surface of the peripheral wall, so that both the front and back surfaces of the shim can be used as cam contact surfaces. When the shim is removed from the tappet body, an angle of an inner chamfered portion of the peripheral wall for guiding a tool which is obliquely inserted into the tool engagement groove is 45 degrees or less.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing a part of a direct-acting valve train having an internal combustion engine tappet according to an embodiment of the present invention. FIG. 2 is an enlarged view of the tappet shown in FIG. FIG. 3 is an enlarged sectional view showing a part of the tappet.

The valve operating mechanism shown in FIG. 1 is for operating an intake valve 3 for opening and closing an intake port 2 formed in a cylinder head 1 of an engine. A spring retainer 4 is provided at a rear end of the intake valve 3. Is attached, and a spring force in a direction to close the intake port 2 is applied to the intake valve 3 by a coil spring 5 assembled to the intake valve 3. In order to drive the intake valve 3 directly by the camshaft 6, a tappet 10 that contacts a cam 7 provided on the camshaft 6 is attached to a rear end of the intake valve 3.

The tappet 10 has a cylindrical tappet body 1 having a cylindrical portion 11 and a top wall 12 provided at one end thereof.
The tappet body 13 is provided with a peripheral wall 14 protruding outward from the outer peripheral portion of the top wall 12, and a housing recess 15 surrounded by the peripheral wall 14 is formed outside the top wall 12. A disk-shaped shim 16 for adjusting valve clearance is detachably disposed in the housing recess 15.

A tool engaging groove 17 is formed in the outer peripheral surface of the shim 16 at a substantially central portion in the thickness direction.
Has a circular arc-shaped concave surface as shown in FIGS. Contact portions 18 having substantially the same thickness dimension B are provided on both sides in the thickness direction of the tool engagement groove 17, respectively. The shim 16 has a symmetrical shape on both sides, and the cam contact surfaces 19a and 19b on both sides. I have.

The thickness dimension B of each contact portion 18 is set to a value smaller than DH when the projection dimension of the peripheral wall 14 from the top wall 12 is H and the thickness dimension of the shim 16 is D. Have been. That is, DH> B is set. Thereby, when the shim 16 is arranged in the accommodation recess 15, the tool engagement groove 17 formed in the outer peripheral surface of the shim 16 at a substantially central portion in the thickness direction is formed by a portion covered by the peripheral wall 14 and an end surface of the peripheral wall 14. Also have a portion communicating with the outside. In addition, the cam contact surfaces 19 on both the front and back sides
In a state where the shim 16 is disposed in the housing recess 15 such that one of the a and 19b is brought into surface contact with the inner peripheral surface of the peripheral wall 14, the other cam contact surface protrudes outward from the end surface of the peripheral wall 14. State.

As described above, a part of the tool engagement groove 17 is exposed to the outside from the end face of the peripheral wall 14 and communicates with the outside, and the other cam contact surface is located outside the end face of the peripheral wall 14. As shown in FIG. 3, a tool 2 such as a flathead screwdriver is inserted between the peripheral wall 14 and the tool engagement groove 17.
A gap into which 0 is inserted is formed.

An inner chamfer 21 is formed at an inner corner of the end face of the peripheral wall 14, and the chamfer angle θ is set to 45 degrees or less, so that the tool 20 can correspond to the chamfer angle θ of the inner chamfer 21. The tool 20 can be inserted at an inclined angle. Therefore, when removing the shim 16, the tool 20 is inserted and the shim 16 is floated, so that the shim 16 can be lifted with tweezers or the like under the floated state or transported to a predetermined position with the tool 20 as it is. Can be. In this way, the shim 1 can be
6 can be removed, so that the peripheral wall 14 and the shim 16 can be prevented from being damaged by the tool 20. Moreover,
In order to remove the shim 16, there is no need for a special replacement tool and a large replacement work space.

As described above, since the shim 16 has a symmetrical shape on both sides, both surfaces can be used as cam contact surfaces, and the cam contact surface is not taken into account when the tappet 10 is assembled. Assembly work can be easily performed.

Moreover, one of the cam contact surfaces 19a is
If the cam contact surface 19a is worn out by operating the valve mechanism by contacting the cam, the shim 16 can be removed and the shim 16 can be reused with the other cam contact surface 19b facing the front side. . Accordingly, when the shim 16 is removed for reuse, it is possible to prevent the shim 16 from being damaged, so that the shim 16 can be surely reused without deteriorating.

In order to remove the shim 16, it is not necessary to form a cutout or a groove in the tappet body 13 or to form a through-hole in the shim 16 unlike the related art, so that the strength of the tappet body 13 can be increased. By preventing a decrease in the contact area between the shim and the cam due to the presence of the through hole, the occurrence of the wear can be prevented.

When the shim 16 is disposed in the accommodation recess 15, one of the contact portions 18 formed on both sides of the shim 16 comes into surface contact with the inner peripheral surface of the peripheral wall 14. Even when the shim 16 is sometimes rotated by vibration, the occurrence of wear of the contact portion 18 can be prevented, and the durability of the shim 16 can be improved.

In the case described above, the tool engaging groove 17 is formed so as to be continuous with the entire outer peripheral surface of the shim 16, but as shown in FIG. The groove 17 may be provided, or only one may be provided.

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0024]

According to the present invention, since the shim has a symmetrical shape on both sides, if wear occurs on the cam contact surface that has been in contact with the cam, the shim is turned upside down to reduce the wear. The shim can be reused by bringing the cam into contact with the cam contact surface that has not been generated. At this time, the shim can be easily removed without damaging the shim or the tappet body with the tool. There is no need to provide a groove or notch in the tappet body, and the strength of the tappet body can be improved. Since it is not necessary to form a through hole in the shim, it is possible to prevent the wear of each of the shims without reducing the contact area between the cam and the shim. Since the outer peripheral surface of the shim has a contact portion in surface contact with the inner surface of the peripheral wall, wear of the outer periphery of the shim can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a part of a direct-acting valve train having a tappet for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the tappet shown in FIG. 1 in an enlarged manner.

FIG. 3 is an enlarged cross-sectional view showing a part of the tappet.

FIG. 4A is a plan view showing a modified example of the shim.
(B) is a side view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Tappet 11 Cylindrical part 12 Top wall 13 Tappet main body 14 Peripheral wall 15 Housing recess 16 Shim 17 Tool engagement groove 18 Contact part 19a, 19b Cam contact surface 20 Tool 21 Chamfer part

Claims (2)

[Claims] 1. A cylindrical tappet main body having a top wall, and a valve clearance adjusting removably disposed in a housing recess surrounded by a peripheral wall formed to protrude outward on an outer peripheral portion of the top wall. A tappet for an internal combustion engine having a disk-shaped shim, and a tool engagement groove formed at a center in a thickness direction of an outer peripheral surface of the shim, partially communicating outward from an end surface of the peripheral wall, A tappet for an internal combustion engine, wherein both the front and back surfaces of the shim can be used as cam contact surfaces. 2. The tappet for an internal combustion engine according to claim 1, wherein when the shim is removed from the tappet main body, an angle of an inner chamfered portion of the peripheral wall for guiding a tool that is obliquely inserted into the tool engagement groove. A tappet for an internal combustion engine, wherein the angle is set to 45 degrees or less.