JP2000130111A - Valve system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tappet of an internal combustion engine, capable of being easily machined by forming the top surface of a shim or a tappet main body into a flat surface without increasing the weight. SOLUTION: A valve system is provided with an engine valve 3 capable of opening and closing an intake and exhaust port 2 of an internal combustion engine, and a rotary cam 11 for opening and closing the engine valve 3. A lifter 15 is arranged between the rotary cam 11 and a valve stem 5 of the engine valve 3. One of contact surfaces of the bottom surface 21 of the lifter 15 and the end surface of the valve stem 5 is formed into a flat surface or a recessed surface, and the other one is formed into a flat surface or a recessed surface having the outer periphery to be brought into line contact with it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a valve train for an internal combustion engine.

[0002]

2. Description of the Related Art This type of valve train for an internal combustion engine slides in a receiving hole formed in a cylinder head between a valve stem of an engine valve capable of opening and closing an intake or exhaust port of the internal combustion engine and a rotary cam. A movable lifter is provided.

The lifter slides in the receiving hole according to the lift amount of the rotary cam to open and close the engine valve. At this time, since the lifter is slidably guided into the accommodation hole formed in the cylinder head, the lifter has an appropriate sliding gap between the lifter and the accommodation hole. There is a risk of rocking movement in the interior.

When the lifter makes a rocking motion, the end of the lifter collides with the inner surface of the receiving hole, and a collision noise is generated.
Japanese Patent Publication No. 7506 proposes a valve gear in which one of contact surfaces between a bottom surface of a lifter and an end surface of a valve stem has a spherical convex surface, and the other has a rotating spherical concave surface in linear contact with one convex surface. Have been.

According to the study by the inventors, the generation of the collision sound of the lifter is caused by the swing of the lifter.
The swing of the lifter is caused by the relative movement of the contact point between the rotary cam and the lifter, and the movement of the contact point is caused by a sliding gap between the lifter and the accommodation hole, Is caused by the rotation.

That is, when the rotating cam starts rotating when the rotating cam is rotating clockwise, the initial lift portion of the rotating cam comes into contact with the lifter, so that the lifter is moved.
The whole is moved to the left (in the rotation direction of the rotating cam) in the sliding gap. For this reason, the contact point between the rotary cam and the lifter is located at point A on the right side of the shaft center position of the lifter. At this time, the length of the arm from the contact point between the bottom surface of the lifter and the valve stem to the contact point (point A) between the rotating cam and the lifter is defined as the arm length, and the spring force of the valve spring is defined as the magnitude of the force. The lifter rotates clockwise about the contact point between the bottom surface of the lifter and the valve stem as a fulcrum.

That is, when the bottom surface of the lifter and the end surface of the valve stem are in point contact with each other at the axis of the lifter, the contact point between the rotary cam and the lifter is determined from the position of the axis of the lifter. The length up to the point A) is defined as the length of the arm, and a moment acts on the force of the spring force of the valve spring, so that the lifter rotates clockwise. In the state where the lifter swings clockwise, the engine valve and its valve stem are also slightly inclined, and the seating of the engine valve on the valve seat surface is not uniform.
There is no particular problem in the opening operation of the engine valve.

The rotary cam keeps contacting at the point A and gradually increases the lift amount to reach the maximum lift position to open the engine valve. At this time, a contact point (point A) between the maximum lift position of the rotary cam and the lifter is a position farthest from the shaft center position of the lifter.

Further, when the rotary cam rotates, the contact point (point A) between the maximum lift position of the rotary cam and the lifter becomes:
It gradually approaches the lifter axis position, moves further to the left over the lifter axis position, and reaches a contact point (point B) on the left side of the lifter axis position. Therefore, the length of the arm of the lifter from the contact point between the bottom surface of the lifter and the valve stem (for example, the position of the shaft center of the lifter) to the contact point (point B) between the rotating cam and the lifter is defined as an arm length. A moment acts on the force of the spring force of the valve spring, and the lifter rotates counterclockwise about a contact point between the bottom surface of the lifter and the valve stem as a fulcrum. When the lifter is turned counterclockwise, the engine valve and the valve stem are also slightly inclined. However, no particular problem occurs when the port is opened by the engine valve.

The rotating cam keeps contacting at the point B, gradually decreasing the lift amount, and closing the engine valve. At this time, when the lifter is rotated counterclockwise, the engine valve and the valve stem are also slightly inclined.

[0011] Contact point (point B) between the rotating cam and the lifter
Is the position at which the contact point between the maximum lift position of the rotating cam and the lifter is farthest from the shaft center position of the lifter, and gradually approaches the shaft center position of the lifter as the rotating cam rotates and the lift amount is reduced. However, since the lifter has a sliding gap, it does not coincide with the axial center position of the lifter. Therefore, when the rotating cam is in contact with the lifter, a counterclockwise moment continues to act on the lifter, the lifter continues to rotate counterclockwise, and the engine valve and the valve stem are also rotated. The slightly inclined state is maintained.

When the lifter is rotated counterclockwise and the valve stem is also slightly inclined, the seating of the engine valve on the valve seat surface is not uniform, and first, one point of the engine valve contacts one point of the valve seat. Then, a so-called one-sided hit occurs. Therefore, a force (correction force) for properly seating the engine valve on the valve seat surface acts on the engine valve by the valve spring. The straightening force by the valve spring gradually increases as the lift amount of the rotary cam is reduced, and becomes maximum when the lift amount by the rotary cam becomes zero. Moves quickly to the correct seating position (as soon as it reaches zero).

The lifter is rotated by an abrupt operation at the time of closing the engine valve, and a collision noise of the lifter is generated.
That is, when the lift by the rotary cam is zero, the force acting on the lifter is zero, and the thermal expansion of the valve train system is absorbed between the rotary cam and the lifter (or between the lifter and the valve stem). A predetermined valve clearance is provided, the sudden movement of the engine valve during the closing operation causes the lifter to float in the accommodation hole,
When the end of the lifter collides with the inner surface of the receiving hole, a collision sound is generated.

That is, according to the analysis of the inventors, the sudden movement of the engine valve during the closing operation causes the lifter to rotate, and the collision sound of the lifter is generated when the engine valve is seated on the valve seat. At this point, the engine valve is slightly inclined.

When the engine valve is closed, the engine valve and the valve stem are inclined when the bottom surface of the lifter and the end surface of the valve stem are in point contact with each other at the axis of the lifter. This is because the contact point (point B) between the lifter and the lifter does not match the axial center position of the lifter, and a moment acts on the lifter.

That is, the contact point (point B) between the rotary cam and the lifter is located radially outward from the axial center position of the lifter, that is, the contact point between the bottom surface of the lifter and the end surface of the valve stem. When the contact point (point B) between the rotating cam and the lifter is located radially inward from the contact point between the bottom surface of the lifter and the end surface of the valve stem, the lifter The moment will not act.

Therefore, during the closing operation of the engine valve, if a counterclockwise moment does not act on the lifter when the engine valve is seated on the valve seat, it is possible to prevent the occurrence of collision noise of the lifter as much as possible. It is.

[0018]

However, in the prior art, one of the contact surfaces between the bottom surface of the lifter and the end surface of the valve stem is formed into a spherical convex surface, and the other is brought into line contact with one convex surface. Because it is a rotating spherical concave surface
The point of contact between the bottom surface of the lifter and the end surface of the valve stem comes as close as possible to the axial position of the lifter.

Therefore, the contact point between the bottom surface of the lifter and the end surface of the valve stem is located as close as possible to the axial center position of the lifter. Therefore, when the engine valve is closed, the contact point ( Point B) is located radially outward of the point of contact between the bottom surface of the lifter and the end surface of the valve stem, and a moment acts on the lifter. As a result, the engine valve is inclined when the engine valve is seated on the valve seat, and the inclination of the engine valve is corrected, so that the lifter swings and the collision noise of the lifter is not sufficiently eliminated. .

The present invention has been devised as a result of the above research, and has as its object to provide a valve train for an internal combustion engine capable of preventing the occurrence of lifter collision noise and reducing noise. And

[0021]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to an engine valve capable of opening and closing an intake or exhaust port of an internal combustion engine, a rotary cam for opening and closing the engine valve, and a rotary cam and an engine. A valve train for an internal combustion engine, comprising a lifter disposed between a valve stem of a valve and slidably guided in a receiving hole formed in a cylinder head, wherein a bottom surface of the lifter and an end surface of the valve stem are provided. One of the contact surfaces is a flat surface or a concave surface, and the other is a concave surface where the outer periphery of the one flat surface or the concave surface is in line contact.

According to a second aspect of the present invention, there is provided an engine valve capable of opening and closing an intake or exhaust port of an internal combustion engine.
An internal combustion engine comprising: a rotary cam for opening and closing the engine valve; and a lifter disposed between the rotary cam and the valve stem of the engine valve and slidably guided in a receiving hole formed in a cylinder head. In the valve gear of the engine, one of the contact surfaces between the bottom surface of the lifter and the end surface of the valve stem is configured to be concave, and the other is configured to be a flat surface or a convex surface in which the outer periphery of one concave surface is in line contact.

In this configuration, the rotation of the rotary cam causes the engine valve to open and close via the lifter. At this time, there is a possibility that the lifter may swing in the range of the sliding gap due to the sliding gap between the lifter and the housing hole.

In the swing of the lifter, the arm length is defined as the length from the contact point between the bottom surface of the lifter and the end face of the valve stem to the contact point between the rotating cam and the lifter (moving from point A to point B). The lifter is caused by a moment acting on the lifter as the magnitude of the spring force of the valve spring. When the lifter swings, the engine valve and the valve stem also slightly swing. Collision noise may occur.

That is, as described above, according to the analysis by the inventors, when the engine valve is closed, the contact point between the rotary cam and the lifter is shifted from the point A at the time of the opening operation to the position of the shaft center of the lifter. Crossing to point B. For this reason, when the bottom surface of the lifter and the end surface of the valve stem are in point contact with each other at the axis position of the lifter, the contact point between the rotary cam and the lifter (point B) ) Is defined as the length of the arm, and the counterclockwise moment in which the spring force of the valve spring is the magnitude of the force, that is, the moment in the opposite direction to the case where the rotating cam and the lifter are in contact at the contact point A. Moment acts. Therefore, the lifter rotates counterclockwise.

When the lifter is rotated counterclockwise, the engine valve and its valve stem are also slightly inclined, and the seating of the engine valve on the valve seat is not uniform. One point of the engine valve comes in contact with one point of the valve seat, so that a so-called one-sided hit occurs.

Therefore, a force (correction force) for properly seating the engine valve on the valve seat acts on the engine valve by the valve spring. The correction force by the valve spring gradually increases as the lift amount of the rotating cam is reduced, and becomes maximum when the lift amount by the rotating cam becomes zero,
With this correction force, the engine valve is rapidly moved to the correct seating position (as soon as the lift by the rotating cam becomes zero).

The lifter swings due to the abrupt operation at the time of closing the engine valve, and a collision noise of the lifter is generated.
That is, when the lift by the rotary cam is zero, the force acting on the lifter is zero, and the thermal expansion of the valve train system is absorbed between the rotary cam and the lifter (or between the lifter and the valve stem). A predetermined valve clearance is provided, the sudden movement of the engine valve during the closing operation causes the lifter to float in the accommodation hole,
When the end of the lifter collides with the inner surface of the receiving hole, a collision noise may be generated.

That is, according to the analysis of the inventors, the sudden movement of the engine valve during the closing operation causes the lifter to swing, and the collision sound of the lifter is generated when the engine valve is seated on the valve seat. At this point, the engine valve is slightly tilted.

When the engine valve is closed, the engine valve and the valve stem are tilted when the bottom surface of the lifter and the end surface of the valve stem are in point contact with each other at the axis of the lifter. Point of contact with lifter (B
(Point) does not match the position of the shaft center of the lifter, and a moment is acting on the lifter.

That is, the point of contact (point B) between the rotary cam and the lifter is located radially outward from the position of the shaft center of the lifter, that is, the point of contact between the bottom surface of the lifter and the end surface of the valve stem. When the contact point (point B) between the rotating cam and the lifter is located radially inward from the contact point between the bottom surface of the lifter and the end surface of the valve stem, the lifter The moment will not act.

Here, in the first aspect of the present invention,
Of the contact surfaces between the bottom surface of the lifter and the end surface of the valve stem, one is a flat surface or a concave surface, and the other is a concave surface where the outer periphery of the one flat surface or the concave surface is in line contact.
For this reason, the point of contact between the bottom surface of the lifter and the end surface of the valve stem is located on one flat surface or the outer periphery of the concave surface of the contact surface and at a position distant from the axial center position of the lifter. Thereby, when the contact point (point B) between the rotary cam and the lifter approaches the axial position of the lifter, the contact point (point B) between the rotary cam and the lifter moves between the bottom surface of the lifter and the end face of the valve stem. Comes inward in the radial direction from the contact point.

[0033] In the invention according to claim 2, one of the contact surfaces between the bottom surface of the lifter and the end surface of the valve stem is a concave surface, and the other is a flat surface where the outer periphery of the one concave surface is in line contact. It is configured as a convex surface. For this reason,
The contact point between the bottom surface of the lifter and the end surface of the valve stem is
The outer periphery of the one concave surface of the contact surface, which is located at a position distant from the axial center position of the lifter. Thereby, when the contact point (point B) between the rotary cam and the lifter approaches the axial position of the lifter, the contact point (point B) between the rotary cam and the lifter moves between the bottom surface of the lifter and the end face of the valve stem. Comes inward in the radial direction from the contact point.

Therefore, the contact point (point B) between the rotary cam and the lifter is the position farthest from the shaft center position of the lifter (the position where the contact point between the maximum lift position of the rotary cam and the lifter is the farthest). ), As the rotating cam rotates and the lift is reduced, the lifter gradually approaches the lifter's shaft center position, and moves radially inward from the point of contact between the bottom surface of the lifter and the valve stem. The counterclockwise moment will not act, and the lifter is aligned by the concave or convex surface of the contact surface between the bottom surface of the lifter and the end surface of the valve stem so that the axis of the lifter and the axis of the valve stem coincide. .

That is, the inclination of the lifter is eliminated and the inclination of the engine valve and the valve stem are eliminated.

Therefore, the engine valve is properly seated without hitting against the valve seat. Thereby, since there is no sudden movement at the time of the closing operation of the engine valve, the lifter does not float in the accommodation hole,
A collision noise does not occur when the end of the lifter collides with the inner surface of the accommodation hole.

Therefore, it is possible to obtain a valve gear for an internal combustion engine capable of preventing the occurrence of a collision noise of the lifter and reducing the noise.

[0038]

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

FIG. 1 is a sectional view of a valve gear for an internal combustion engine showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing a main part of FIG. 1, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a view similar to FIG. 2 showing an embodiment, FIG. 4 is a view illustrating a state in which the lifter is rotated counterclockwise, and FIG. 5 is a view illustrating a state in which the axis of the lifter and the axis of the valve stem coincide. It is.

In FIG. 1, reference numeral 1 denotes a cylinder head of the internal combustion engine, and 2 denotes an intake or exhaust port (hereinafter simply referred to as a port) formed in the cylinder head 1.

Reference numeral 3 denotes an engine valve. The engine valve 3 is seated on a valve seat 4 provided at an end of a port 2 of the internal combustion engine, and the port 2 can be opened and closed. In the engine valve 3, a valve stem 5 of the engine valve 3 is slidably guided by a valve guide 6.

Reference numeral 7 denotes a valve spring. The valve spring 7 is disposed between the cylinder head 1 and a spring receiver 8 attached to the valve stem 5, and constantly urges the engine valve 3 in the direction in which the port 2 is closed. I have.

Reference numeral 11 denotes a rotating cam for opening and closing the engine valve 3. The rotary cam 11 has a lift portion 13 formed on the outer circumference of a reference circle 12. The rotation center of the rotary cam 11 is the axis Ys of the valve stem 5.
Are arranged so as to approximately match.

Reference numeral 15 denotes a lifter disposed between the valve stem 5 of the engine valve 3 and the rotary cam 11.
The lifter 15 includes a cylindrical lifter main body 16 and a shim 17 provided on the top surface of the lifter main body 16, and is slidably accommodated in an accommodation hole 18 formed in the cylinder head 1. In a normal state, the axis Yl of the lifter 15 coincides with the axis Ys of the valve stem 5 and the rotation center of the rotary cam 11.

The bottom surface 21 of the lifter 15 is in contact with the end surface 22 of the valve stem 5, and in this embodiment, one contact surface, that is, the end surface 22 of the valve stem 5 is concave, and the other contact surface is concave. Surface, that is, the bottom surface 21 of the lifter
Is a concave surface in contact with the outer periphery of the concave surface of the end surface 22 of the valve stem 5. Further, the bottom surface 21 of the lifter 15 may be formed by burying a hard chip 23 as shown in FIG.

In such a configuration, the rotation of the rotary cam 11 causes the engine valve 3 to open and close via the lifter 15. At this time, there is a possibility that the lifter 15 may swing within the range of the sliding gap due to the sliding gap between the lifter 15 and the housing hole 18.

The swing of the lifter 15 is caused by the point of contact between the bottom surface 21 of the lifter 15 and the end face of the valve stem 5 and the point of contact between the rotary cam 11 and the lifter 15 (this point of contact is In the case of rotation, the arm moves from the point A on the right side to the point B on the left side with respect to the axis Yl) as the length of the arm, and the moment that makes the spring force of the valve spring 7 the magnitude of the lifter is a lifter. When the lifter 15 swings, the engine valve 3 and the valve stem 5 also slightly swing, which may cause a collision noise of the lifter 15.

That is, as described above, according to the analysis by the inventors, when the engine valve 3 is closed, the contact point between the rotary cam 11 and the lifter 15 is shifted from the point A at the time of the open operation to the lifter 15. It reaches point B beyond the axis position. Therefore, when the bottom surface 21 of the lifter 15 and the end surface 22 of the valve stem 5 are in point contact with each other at the axial center position of the lifter 15, the lifter 15 is connected to the rotary cam 11 from the axial center position of the lifter 15. The length to the contact point (point B) with the lifter 15 is defined as the arm length, and the counterclockwise moment that sets the spring force of the valve spring 7 to the magnitude of the force, that is, the contact point A between the rotating cam 11 and the lifter 15 A moment acts in the opposite direction to that at the time of contact at a point. Therefore, the lifter 15
Rotates counterclockwise (see FIG. 4).

When the lifter 15 is rotated counterclockwise, the engine valve 3 and its valve stem 5 are also slightly inclined, and the seating of the engine valve 3 on the valve seat 4 is not uniform, so that the engine valve 3 When closing,
First, one point of the engine valve 3 comes into contact with one point of the valve seat 4, so that a so-called one-side contact occurs.

For this reason, a force (correcting force) for properly seating the engine valve 3 on the valve seat 4 acts on the engine valve 3 by the valve spring 7. The straightening force by the valve spring 3 gradually increases as the lift amount of the rotary cam 11 is reduced, and becomes maximum when the lift amount by the rotary cam 11 becomes zero. At the same time as the amount of lift by 11 becomes zero), the vehicle suddenly moves to the correct seating position.

The lifter 15 swings due to the abrupt movement of the engine valve 3 when the engine valve 3 is closed, and a collision sound of the lifter 15 is generated. That is, when the lift by the rotary cam 11 is zero, the force acting on the lifter 15 is zero, and a predetermined valve is provided between the rotary cam 11 and the lifter 15 to absorb the thermal expansion of the valve train system. Since the clearance is provided, the sudden movement of the engine valve 3 during the closing operation causes the lifter 15 to move in the accommodation hole 18, and the end of the lifter 15 collides with the inner surface of the accommodation hole 18. Collision noise may occur.

That is, according to the analysis of the inventors, the sudden movement of the engine valve 3 during the closing operation causes the lifter 15 to swing, and the collision sound of the lifter 15 is generated because the engine valve 3 This is because the engine valve 3 is slightly inclined at the time of sitting on the valve seat 4.

When the engine valve 3 is closed, the engine valve 3 and the valve stem 5 are tilted because the bottom surface 21 of the lifter 15 and the end surface 22 of the valve stem 5 are in point contact with each other at the axial position of the lifter 15. In this case, the contact point (point B) between the rotating cam 11 and the lifter 15 does not match the axial center position of the lifter 15, and a moment acts on the lifter 15.

That is, the point of contact (point B) between the rotary cam 11 and the lifter 15 is more radially than the position of the axis of the lifter 15, that is, the point of contact between the bottom surface 21 of the lifter 15 and the end surface 22 of the valve stem 5. Since it is on the outside, a moment acts on the lifter 15, and the contact point (point B) between the rotating cam and the lifter is determined by the bottom surface 21 of the lifter 15 and the valve stem 5.
No moment acts on the lifter 15 when it is located radially inward of the point of contact with the end face 22 of the lifter.

Here, in the present invention, the lifter 1
Of the contact surfaces between the bottom surface 21 of the valve stem 5 and the end surface 22 of the valve stem 5, the end surface of the valve stem 5 is formed into a concave surface, and the end surface 22 of the lifter 15 is formed into a concave surface in which the outer periphery of the concave surface of the valve stem 5 makes line contact. is there. For this reason, the contact point between the bottom surface 21 of the lifter 15 and the end surface 22 of the valve stem 5 is the outer periphery of the end surface (concave surface) of the valve stem 5 and
5 is located away from the axis position. Accordingly, when the contact point (point B) between the rotary cam 11 and the lifter 15 approaches the axis of the lifter 15, the contact point (point B) between the rotary cam 11 and the lifter 15 is set at the bottom of the lifter 15. 21
Is located radially inward of the point of contact between the valve stem 5 and the end face 22 of the valve stem 5.

Therefore, the rotary cam 11 and the lifter 1
5 from the position farthest from the axial center position of the lifter 15 (the maximum lift position of the rotary cam 11 and the position where the contact point with the lifter 15 is farthest). As the lift amount decreases and the lift amount decreases, the lifter 15 gradually approaches the axial center position of the lifter 15, and reaches radially inward from the contact point 22 between the bottom surface 21 of the lifter 15 and the valve stem 5. The counterclockwise moment does not act, and the lifter 15 is centered by the concave surface of the contact surface between the bottom surface 21 of the lifter 15 and the end surface 22 of the valve stem 5 so that the axis Yl of the lifter 15 and the valve stem 5 (See FIG. 5).

That is, the inclination of the lifter 15 is eliminated and the inclination of the engine valve 3 and the valve stem 5 are eliminated.

Therefore, the engine valve 3 is properly seated without hitting against the valve seat 4. As a result, since there is no sudden movement during the closing operation of the engine valve 3, the lifter 15 does not move in the accommodation hole 18, and the end of the lifter 15 collides with the inner surface of the accommodation hole 18. Collision noise is prevented.

Further, since the inclination of the valve stem 5 is eliminated, the collision sound between the valve stem 5 and the valve guide 6 can be prevented.

Accordingly, it is possible to obtain a valve gear for an internal combustion engine capable of preventing the occurrence of the collision noise of the lifter 15 and reducing the noise.

FIGS. 5 and 7 are views showing another embodiment of the present invention. This embodiment is different from the above-described embodiment in that the bottom surface 21 of the lifter 15 and the valve stem 5 are different from each other.
One of the contact surfaces with the end surface 22 is a flat surface, and the other is a concave surface in which the outer periphery of one of the planes is in line contact.

That is, the bottom surface 21 of the lifter 15 is in contact with the end surface 22 of the valve stem 5, and in this embodiment, one contact surface, that is, the end surface 22 of the valve stem 5 is provided.
Is a flat surface, and the other contact surface, that is, the bottom surface 21 of the lifter is a concave surface in contact with the outer periphery of the flat surface of the end surface 22 of the valve stem 5. The bottom surface 21 of the lifter 15 is formed by embedding a hard chip 23 as shown in FIG.

In such a configuration, the end surface of the valve stem 5 is a flat surface, and the end surface 22 of the lifter 15 is a concave surface in which the outer periphery of the flat surface of the valve stem 5 is in line contact. The point of contact with the end face 22 is the outer periphery of the end face (plane) of the valve stem 5,
The lifter 15 is located at a position distant from the axial center position. Thereby, the contact point (B) between the rotary cam 11 and the lifter 15
(Point B) approaches the shaft center position of the lifter 15, the contact point (point B) between the rotary cam 11 and the lifter 15 is
Of the valve stem 5 and the end surface 22 of the valve stem 5 inward in the radial direction.

Therefore, similarly to the above embodiment, when the engine valve 3 is closed, the engine valve 3 is properly seated without hitting against the valve seat 4. As a result, the lifter 15 does not move, and no collision noise is generated.

Therefore, also in this embodiment,
A valve train for an internal combustion engine capable of preventing the occurrence of collision noise of the lifter 15 and reducing noise is obtained.

FIG. 8 is a view showing another embodiment of the present invention. This embodiment is different from the above embodiment in that a contact surface between a bottom surface 21 of the lifter 15 and an end surface 22 of the valve stem 5 is provided. Among them, one is a concave surface, and the other is a flat or convex surface where the outer periphery of one concave surface is in line contact.

That is, the bottom surface 21 of the lifter 15 is in contact with the end surface 22 of the valve stem 5, and in this embodiment, one contact surface, that is, the end surface 22 of the valve stem 5 is provided.
Are concave, and the other contact surface, that is, the bottom surface 21 of the lifter is a convex surface with which the outer periphery of the concave surface of the end surface 22 of the valve stem 5 is in contact. The bottom surface 21 of the lifter 15 may be a flat surface, or may be formed by embedding a hard chip.

In such a configuration, the end surface of the valve stem 5 is formed as a concave surface, and the end surface 22 of the lifter 15 is formed as a convex surface in which the outer periphery of the concave surface of the valve stem 5 is in line contact. The point of contact with the end face 22 is the outer circumference of the end face (concave face) of the valve stem 5,
The lifter 15 is located at a position distant from the axial center position. Thereby, the contact point (B) between the rotary cam 11 and the lifter 15
(Point B) approaches the shaft center position of the lifter 15, the contact point (point B) between the rotary cam 11 and the lifter 15 is
Of the valve stem 5 and the end surface 22 of the valve stem 5 inward in the radial direction.

For this reason, as in the above embodiment, when the engine valve 3 is closed, the engine valve 3 is properly seated without hitting against the valve seat 4. As a result, the lifter 15 does not move, and no collision noise is generated.

Therefore, also in this embodiment,
A valve train for an internal combustion engine capable of preventing the occurrence of collision noise of the lifter 15 and reducing noise is obtained.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment and can be changed without departing from the spirit of the invention.

[0072]

As described above in detail, according to the present invention, it is possible to obtain a valve gear of an internal combustion engine capable of preventing the occurrence of a collision noise of a lifter and reducing the noise. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a valve gear of an internal combustion engine showing an embodiment of the present invention.

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

FIG. 3 is a drawing similar to FIG. 2, showing another embodiment of the present invention.

FIG. 4 is a drawing for explaining a state in which the lifter has turned counterclockwise.

FIG. 5 is a view for explaining a state where the axis of the lifter and the axis of the valve stem coincide with each other.

FIG. 6 is a view similar to FIG. 2, showing another embodiment of the present invention.

FIG. 7 is a drawing similar to FIG. 2, showing another embodiment of the present invention.

FIG. 8 is a view similar to FIG. 2, showing another embodiment of the present invention.

[Explanation of symbols]

 2 Port 3 Engine Valve 5 Valve Stem 11 Rotating Cam 15 Lifter 18 Housing Hole 21 Bottom 22 End

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shoji Hayashi 1370 Onna, Atsugi-shi, Kanagawa F-term in Unisia Gex Co., Ltd. (reference) 3G016 AA19 BB04 CA04 CA06 CA13 CA41 GA04

Claims (2)

[Claims] 1. An engine valve capable of opening and closing an intake or exhaust port of an internal combustion engine, a rotating cam for opening and closing the engine valve, and a rotating cam disposed between the rotating cam and a valve stem of the engine valve. In a valve operating device for an internal combustion engine comprising a lifter slidably guided in a formed receiving hole, one of contact surfaces between a bottom surface of the lifter and an end surface of a valve stem is a flat surface or a concave surface, A valve train for an internal combustion engine, characterized in that the other has a flat surface or a concave surface where the outer periphery of the concave surface is in line contact. 2. An engine valve capable of opening and closing an intake or exhaust port of an internal combustion engine, a rotary cam for opening and closing the engine valve, and a rotary cam disposed between the rotary cam and a valve stem of the engine valve. In a valve operating device for an internal combustion engine comprising a lifter slidably guided in a formed receiving hole, one of a contact surface between a bottom surface of the lifter and an end surface of a valve stem is a concave surface, and the other is a concave surface. A valve train for an internal combustion engine, wherein the outer periphery of one concave surface is a flat surface or a convex surface that makes line contact.