JP2000356113A - Valve lifter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase of friction even when an attitude change occurs during lifting. SOLUTION: This valve lifter comprises a tappet part 4 making contact with a cam 3; and a guide part 5 slidably contained in the guide hole 6 of a cylinder head 2. A peripheral groove 8 is provided to promote elastic deformation of a guide part 5 during containing of the guide part 5 in a guide hole 6. This constitution causes the guide part to follow the shape of the guide hole 6 by promoting elastic deformation of the guide part 5 when an attitude change occurs to a valve lifter 1 during lifting, prevents the increase of friction, and reduces the generation of strike noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-acting valve lifter for driving a valve of an internal combustion engine, which is intended to reduce friction caused by a change in posture.

[0002]

2. Description of the Related Art A direct hit type valve lifter is conventionally known, for example, from Japanese Patent Application Laid-Open No. Hei 10-331709. The direct hit type valve lifter has a tappet portion that contacts a cam disposed above a cylinder head of the internal combustion engine, and a guide portion that is slidably received in a guide hole of the cylinder head. The valve lifter is disposed between the cam and the valve, and the rotation of the cam causes the tappet portion to be pressed by the cam ridge and the guide portion to slide on the cylinder head. Thereby, the valve is moved in the axial direction integrally with the valve lifter, and the intake port or the exhaust port is opened and closed.

[0003]

The tappet portion of the valve lifter in contact with the cam ridge of the cam has a substantially circular flat surface, and the tappet portion and the cam ridge are in linear contact. For this reason, the contact position moves within the diameter of the tappet portion, the load point of the tappet portion changes, and the valve lifter receives the opposite moment when reciprocating. In many internal combustion engines, the cylinder head is made of aluminum, the valve lifter is made of iron, and a predetermined clearance is set between the guide hole and the valve lifter so that the valve lifter can move even at extremely low temperatures. . For this reason, at high temperatures, the clearance between the guide hole and the valve lifter increases, and when a moment acts on the valve lifter, the inclination increases. on the other hand,
Since the tappet portion of the valve lifter has a disk shape, the rigidity of the outer peripheral portion is high and the tappet portion is not easily deformed.

[0004] Therefore, when the valve lifter undergoes a large change in attitude during the maximum lift, when the tappet portion hits the inner surface of the guide hole, the oil film of the clearance is pushed away, generating a loud metal tapping sound and increasing friction and wear. And the deterioration of the output and fuel economy of the internal combustion engine.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a valve lifter that does not increase friction even if the posture changes during a lift.

[0006]

According to the present invention, there is provided a valve lifter disposed between a cam and a valve disposed above a cylinder head of an internal combustion engine. A guide portion slidably housed in a guide hole of the cylinder head, and an elastic deformation promoting mechanism for promoting elastic deformation of the guide portion when the guide portion is housed in the guide hole. When it occurs, the elastic deformation of the guide portion is promoted, the increase in friction is prevented, and the hitting sound and the like are reduced.

Preferably, the position of the valve lifter at the time of the maximum lift is set so that only the guide portion is housed in the guide hole. The elastic deformation promoting mechanism is
It is composed of a groove-shaped recess or hole formed continuously or intermittently in the circumferential direction at the boundary between the tappet portion and the guide portion. Further, when the tappet portion is formed to have a larger diameter than the guide portion, it is preferable to form a groove around the base of the tappet portion, and the groove allows the back surface of the tappet portion and the outer peripheral surface of the guide portion to be formed. Since the slack portion is formed in the polishing, the processing of the valve lifter can be facilitated.

[0008]

FIG. 1 shows a schematic configuration of a valve lifter according to an embodiment of the present invention, FIG. 2 shows a schematic configuration of a valve lifter before a maximum lift, and FIG. 3 shows a line III-III in FIG. FIG. 4 shows a schematic configuration of the valve lifter after the maximum lift, and FIG. 5 shows a VV line in FIG.

As shown in FIG. 1, the valve lifter 1 has a tappet portion 4 that contacts a cam 3 disposed above a cylinder head 2 of an internal combustion engine. The tappet 4 and the cam ridge of the cam 3 are in linear contact with each other. The valve lifter 1 further includes a hollow cylindrical guide portion 5 having the same diameter as the tappet portion 4 continuously below the tappet portion 4, and the guide portion 5 is slidably received in a guide hole 6 of the cylinder head 2. ing.

The top of the shaft of the valve 7 is disposed in contact with the guide portion 5 of the valve lifter 1, and the valve 7 is urged upward by a spring (not shown). That is, the valve lifter 1 is disposed between the cam 3 and the valve 7. The rotation of the cam 3 causes the cam lobe to come into contact with the tappet portion 4 to push down the valve lifter 1, and the valve 7 is pushed down together with the valve lifter 1 against the urging force of the spring to open the valve. The position where the valve 7 is pushed down to the maximum, that is, the position when the valve lifter 1 is at the maximum lift is a state where only the guide portion 5 is accommodated in the guide hole 6 (a state where the tappet portion 4 is not accommodated in the guide hole 6). Is set to

A peripheral groove 8 as an elastic deformation promoting mechanism is formed on the outer peripheral portion of the valve lifter 1 between the tappet portion 4 and the guide portion 5, and when the guide portion 5 is housed in the guide hole 6 by the peripheral groove 8. The elastic deformation of the guide portion 5 is promoted. As the elastic deformation promoting mechanism, it is also possible to adopt a configuration other than the circumferential groove 8 such as arranging holes and recesses uniformly in the circumferential direction, and forming the guide portion 5 in a thin state. If the valve lifter 1 is rotatable as a countermeasure against uneven wear of the valve lifter 1, it is preferable to provide an elastic deformation promoting mechanism so that the same deformation can be obtained over the entire circumference of the valve lifter 1.

In the valve lifter 1 having the above structure, as shown in FIGS. 2 and 3, from the start of the lift of the valve lifter 1 to the maximum lift, the load is applied to the surface of the tappet portion 4 on the right side in FIG. The working moment is generated in the same direction as the rotation direction of the cam 3. This allows
The valve lifter 1 tilts rightward in the drawing, and the clearance above the right side between the guide portion 5 and the guide hole 6 becomes small.

When the attitude of the valve lifter 1 changes due to a moment acting in the same direction as the rotation direction of the cam 3, the tappet portion 4 is not accommodated in the guide hole 6 and the peripheral groove 8 is provided in the outer peripheral portion of the valve lifter 1. Then, the guide part 5 is elastically deformed and follows the shape of the guide hole 6. For this reason,
The lubricating oil between the guide portion 5 and the guide hole 6 is not displaced, the formation of an oil film is maintained, no tapping noise is generated, the generation of wear is suppressed, and the friction is reduced.

As shown in FIGS. 4 and 5, the valve lifter 1
After the maximum lift, the load is applied to the surface of the tappet portion 4 on the left side in FIG. As a result, the valve lifter 1 tilts to the left in the drawing, and the guide portion 5
And the clearance above the left side of the guide hole 6 becomes smaller.

When the attitude of the valve lifter 1 changes due to a moment acting in the direction opposite to the rotation direction of the cam 3, the tappet portion 4 is not accommodated in the guide hole 6 and the peripheral groove 8 is provided in the outer peripheral portion of the valve lifter 1. Then, the guide portion 5 is elastically deformed in the reverse direction and follows the shape of the guide hole 6.
For this reason, the lubricating oil between the guide part 5 and the guide hole 6 is not pushed away, the formation of the oil film is maintained, the tapping noise is not generated, the generation of wear is suppressed, and the friction is reduced.

[0016] For this reason, the friction is reduced and the beating noise when the attitude of the valve lifter 1 changes can be reduced, and the wear is reduced and the durability is improved.

A second embodiment of the present invention will be described with reference to FIG. FIG. 6 shows a schematic configuration of a valve lifter according to a second embodiment of the present invention. Note that the same members as those shown in FIGS. 1 to 5 are denoted by the same reference numerals, and redundant description is omitted.

As shown in the figure, a cylindrical guide portion 12 of a valve lifter 11 is slidably accommodated in a guide hole 6 of a cylinder head 2, and a disc-shaped tappet portion 13 is integrally formed above the guide portion 12. It is provided in. Tappet part 13
Is larger than the diameter r of the guide portion 12, and the tappet portion 13 is formed in an umbrella shape on the upper portion of the guide portion 12.

The portion of the tappet portion 13 which is in contact with the cam ridge of the cam 3 has a substantially flat circular shape, and the tappet portion 13 and the cam ridge of the cam 3 are in linear contact. The position where the valve 7 is pushed down to the maximum, that is, the position when the valve lifter 11 is at the maximum lift is a state where only the guide portion 12 is housed in the guide hole 6 (a state where the tappet portion 16 is not housed in the guide hole 6). Is set to

A circumferential groove 14 is formed around the guide portion 12 at the base of the tappet portion 13 as an elastic deformation promoting mechanism. When the guide portion 12 is received in the guide hole 6 by the circumferential groove 14, the guide groove 12 is formed. Elastic deformation is promoted.
Due to the circumferential groove 14, the back surface of the tappet 13 and the guide 1
Since the slack portion is formed in the polishing process on the outer peripheral surface of No. 2, the processing of the valve lifter 11 can be facilitated.

In the valve lifter 11 having the above-described structure, a load is applied on the surface of the tappet section 13 on the right side in the drawing from the start of the lift of the valve lifter 11 to the maximum lift, and after the maximum lift of the valve lifter 11, the tappet section 13 on the opposite side is lifted. Load is received on the surface. Therefore, the moment acting on the valve lifter 11 is generated in the same direction as the rotation direction of the cam 3 and in the opposite direction. Thereby, the valve lifter 14
Is inclined right and left, and the clearance between the guide portion 12 and the guide hole 6 is reduced.

When the attitude of the valve lifter 11 changes due to the moment acting upon the rotation of the cam 12, the tappet 13 is not accommodated in the guide hole 6 and a circumferential groove 14 is formed around the guide 12 at the base of the tappet 13. Since the guide portion 12 is provided, the guide portion 12 is elastically deformed to be in a state following the shape of the guide hole 6. For this reason, the lubricating oil between the guide portion 12 and the guide hole 6 is not displaced, the formation of the oil film is maintained, the tapping noise is not generated, the generation of wear is suppressed, and the friction is reduced. Since the tappet portion 13 is formed in an umbrella shape having a large diameter, the cam 1
2, the contact area with the cam ridge can be increased, and the lift amount due to the rotation of the cam 12 can be increased without impairing the weight reduction.

As a result, the friction can be reduced and the beating noise when the attitude of the valve lifter 11 changes can be reduced, and the wear can be reduced and the durability can be improved. Further, the lift amount can be increased, and the output can be improved.

A third embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a schematic configuration of a valve lifter according to a third embodiment of the present invention. Note that the same members as those shown in FIGS. 1 to 5 are denoted by the same reference numerals, and redundant description is omitted.

As shown in the figure, the valve lifter 21 has a tappet portion 24 and a guide portion 5 having the same diameter as the tappet portion 24 continuously below the tappet portion 24. When the valve lifter 21 is fully lifted, the guide hole extends to the tappet portion 24. 6. A peripheral groove 28 as an elastic deformation promoting mechanism is formed on the back side of the tappet portion 24, and the peripheral groove 28 promotes elastic deformation of the guide portion 5 when the valve lifter 21 is accommodated in the guide hole 6. In the conventional structure, the rigidity in the vicinity of the tappet portion 24 is high and the elastic deformation of the guide portion 5 is restricted even when the guide portion 5 is in contact with the guide hole 6. The portion 5 is easily deformed elastically.

For this reason, the friction is reduced and the beating noise when the attitude of the valve lifter 21 changes can be reduced, and the wear is reduced and the durability is improved.

A fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 shows a schematic configuration of a valve lifter according to a fourth embodiment of the present invention. Note that the same members as those shown in FIGS. 1 to 5 are denoted by the same reference numerals, and redundant description is omitted.

As shown in the figure, the valve lifter 31 is provided with a tappet portion 34 and a guide portion 5 continuously below the tappet portion 34. When the valve lifter 31 is fully lifted, the tappet portion 34 is accommodated in the guide hole 6. Tappet part 34
Is set smaller than the diameter of the guide portion 5, and a step portion 38 is formed as an elastic deformation promoting mechanism. Therefore, even if the tappet portion 34 is accommodated in the guide hole 6 and the valve lifter 31 changes its posture, the tappet portion 34 does not abut on the guide hole 6. Not regulated.

For this reason, the friction can be reduced and the beating noise when the posture of the valve lifter 31 changes can be reduced, and the wear can be reduced and the durability can be improved.

[0030]

According to the valve lifter of the present invention, a valve lifter disposed between a cam and a valve disposed above a cylinder head of an internal combustion engine slides a tappet portion in contact with the cam and a guide hole of the cylinder head. A guide portion movably housed, and an elastic deformation promoting mechanism for promoting elastic deformation of the guide portion when the guide portion is housed in the guide hole. The elastic deformation of the guide portion is promoted by the deformation promoting mechanism to follow the shape of the guide hole, thereby preventing an increase in friction and reducing a tapping sound and the like. As a result, the friction is reduced and the beating noise when the posture of the valve lifter is changed can be reduced, and the wear is reduced and the durability is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a valve lifter according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a valve lifter according to an embodiment of the present invention.

FIG. 3 is a view taken along the line III-III in FIG. 2;

FIG. 4 is a schematic configuration diagram of a valve lifter according to an embodiment of the present invention.

FIG. 5 is a view taken along line VV in FIG. 4;

FIG. 6 is a schematic configuration diagram of a valve lifter according to a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a valve lifter according to a third embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a valve lifter according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1, 11, 21, 31 Valve lifter 2 Cylinder head 3 Cam 4, 13, 24, 34 Tappet part 5, 12 Guide part 6 Guide hole 7 Valve 8, 14, 28 Circumferential groove 38 Step part

Claims (1)

[Claims] A tappet portion that contacts a cam disposed above a cylinder head of an internal combustion engine; and a guide portion that is slidably received in a guide hole of the cylinder head. A valve lifter disposed between the guide lifter and the valve guide, further comprising an elastic deformation promoting mechanism for promoting elastic deformation of the guide portion when the guide portion is accommodated in the guide hole.