JPH11324617A - Valve lifter for direct type valve system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and compact valve lifter capable of using a lifter diameter effectively. SOLUTION: A fitting recessed part 13 is arranged on an inner surface of an end plate 12 of a lifter body 11 assembled between a cam and a valve stem. A flange 15 arranged on an end part of a nut member 14 is fitted and fixed to the fitting recessed part 13, and the whole of upper surface of the end plate 12 is effectively utilized as a cam contact surface. An adjust bolt 18 moved to a valve stem side while rotating by push-pressing of a spring 21 is screwed and fitted into a screw hole 17 of the nut member 14 so as to regulate a clearance of a valve. It is thus possible to form the length of an axial direction of the valve lifter in a compact type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve lifter of a direct type valve train in which a valve is directly pushed down by rotation of a cam to open the valve.

[0002]

2. Description of the Related Art In general, in a direct type valve train in which an intake valve and an exhaust valve are directly pushed down by rotation of a cam, a valve lifter is incorporated between the cam and an upper end of a valve stem, and the valve lifter is connected to the valve stem. The cam is pressed against the cam by the resilience of a valve spring applied to the cam, and the valve clearance between the valve stem and the cam is adjusted by a valve lifter pushed down by contact with the cam.

[0003] The valve lifter is disclosed in Japanese Utility Model Laid-Open No. 3-86.
The one described in Japanese Patent Publication No. 03 is known conventionally.
In this valve lifter, a nut member is brought into contact with a lower surface of an end plate of a lifter body incorporated between a cam and a valve, and a locking plate is attached to a lower end of an adjusting bolt screw-engaged with the nut member. The spring force of the return spring is applied to the adjusting plate to apply a rotational force in the protruding direction to the adjusting bolt, so that the lower end of the adjusting bolt is brought into contact with the valve stem.

In the above-described valve lifter, when the distance between the cam and the upper end of the valve stem changes due to a temperature change or the like, the adjusting bolt moves in the axial direction while rotating due to the elasticity of the return spring to absorb the change in the distance. There is no gap between the cam and the valve lifter and between the valve lifter and the valve stem, and the valve can be opened and closed with high accuracy.

[0005]

In the valve lifter described above, the adjusting bolt is screw-engaged with a nut member abutting on the lower surface of the end plate of the lifter body. The length to the lower end of the valve train is long, and the axial length of the valve train is long, so that there is a point to be improved in miniaturizing the valve train.

In addition, since the adjusting bolt protrudes greatly below the lower surface of the end plate of the lifter body, the spring seat attached to the upper portion of the valve stem must necessarily be provided below. For this reason, a large space for installing the valve spring cannot be secured below the spring seat, and the single valve spring has insufficient elasticity to open and close the valve with high accuracy. There is something left to do.

In order to solve the above-mentioned inconvenience of the valve lifter, the present applicant has already proposed a valve lifter shown in FIG. In this valve lifter, a screw hole 32 is provided in an end plate 31 of a cylindrical lifter body 30, and an upper opening of the screw hole 32 is closed by a plate 33 attached to an upper surface of the end plate 31. The adjusted adjust bolt 34 is pressed by a spring 35 to give the adjust bolt 34 a downward projecting property.

In the valve lifter, the screw hole 32 is formed in the end plate 31 and the adjustment bolt 34 is engaged with the screw. Therefore, the axial length of the valve lifter is short. It is characterized in that the axial length of the valve train can be reduced.

In the valve lifter shown in FIG. 4, a fitting recess 36 is formed on the upper surface of the end plate 31 of the lifter body 30.
Is formed, and the plate 33 is attached by press-fitting into the fitting concave portion 36.
It is necessary to machine the inner diameter surface of the plate 33 and the outer diameter surface of the plate 33 with high accuracy.
Since the outer diameter of No. 3 becomes the diameter of the lifter of the cam, the diameter of the lifter cannot be used effectively, and there are still points to be improved in workability and effective use of the diameter of the lifter.

It is a technical object of the present invention to effectively utilize a lifter diameter while taking advantage of the characteristics of a valve lifter already proposed.

[0011]

According to the present invention, there is provided a cylindrical lifter body which is assembled between an end of a cam and a valve stem and is slidably supported in an axial direction. A nut member incorporated into the lifter body, and an adjust bolt which is screw-engaged with a screw hole of the nut member and moves toward the valve stem while rotating by pressing of a spring incorporated in the screw hole, A fitting recess is provided on the inner surface of the end plate that comes into contact with the cam of the lifter body, and a nut member is fitted and fixed to the fitting recess.

Here, the nut member can be fixed by a method of brazing or a method of caulking the periphery of the opening of the fitting recess.

As described above, the entire upper surface of the end plate in the lifter body can be used as a cam contact surface by fitting and fixing the nut member to the fitting concave portion provided on the lower surface of the end plate. The lifter diameter can be used effectively.

Further, in the present invention, the screw hole of the nut member and the thread of the adjusting bolt are loaded from the valve stem to the adjusting bolt in order to smoothly absorb the change in the distance between the cam and the end face of the valve stem. The flank angle of the pressure-side flank receiving the axial pushing force is larger than the flank angle of the play-side flank.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a valve train for opening and closing an intake port. Opening / closing valve 3 for intake port 2 formed in cylinder head 1
Has a valve stem 3a, and the valve stem 3a is slidably supported in the axial direction by a stem guide 4 attached to the cylinder head 1.

A valve lifter 10 is incorporated between the valve stem 3a and the cam 5 provided above the valve stem 3a. The valve lifter 10 is slidable along a guide hole 7 formed in the cylinder head 1.

As shown in FIG. 2, the valve lifter 10
It has a cylindrical lifter body 11 whose upper part is closed. The fitting recess 1 is provided on the inner surface of the end plate 12 of the lifter body 11.
3 is formed, and a flange 15 provided on an upper part of the nut member 14 is fitted and fixed to the fitting concave portion 13.

In fixing the flange 15, here, a means by brazing is adopted, and reference numeral 16 denotes a bonding layer thereof.

An adjusting bolt 18 is screwed into a screw hole 17 of the nut member 14, and the adjusting bolt 1
A spring seat 20 and a spring 21 are incorporated between the bottom surface of the concave portion 19 formed on the bottom surface 8 and the lower surface of the end plate 12,
The spherical surface 20 a formed at the lower end of the spring seat 20 is pressed against the bottom surface of the concave portion 19 by the spring 21 to make point contact.

As shown in FIG. 1, a valve retainer 22 is mounted on the valve stem 3a. The valve retainer 22 is provided with a valve spring 2 incorporated below the valve retainer 22.
3, the upper end of the valve stem 3a is pressed against the lower end of the adjustment bolt 18, and the upper surface of the end plate 12 of the valve lifter 10 is
Is pressed against.

As shown in FIG. 2, the adjusting bolt 18 and the thread of the screw hole 17 with which the adjusting bolt 18 is screwed are pushed in from the valve stem 3a to the adjusting bolt 18 in the axial direction. The flank angle of the pressure side flank 24 receiving the force is the play side flank 25
The adjusting bolt 18 is configured to move downward while rotating by the elastic force of the spring 21 due to the relationship between the flank angle and the lead angle of the serrated thread. When the adjusting bolt 18 receives a pushing force from the valve stem 3a, the pushing force is received by the pressure side flank 24, so that the adjusting bolt 18 is hard to rotate, and rotates in a direction in which the adjusting bolt 18 is gradually pushed by the rotational vibration of the cam 5. Then, it is moved upward while rotating to a position where the pushed-side rotation angle and the protrusion-side rotation angle are balanced.

Now, when the cam 5 is rotated and the valve lifter 10 is pushed down by the protrusion 5a of the cam 5, the valve stem 3a is pushed down by the adjusting bolt 18, and the valve 3 is lowered to open the intake port 2. When the base circle 5b of the cam 5 is opposed to the end plate 12 of the lifter body 11, the valve 3 and the valve lifter are raised by the elasticity of the valve spring 23, and the intake port 2 is closed.

When the valve 3 is opened and closed as described above, the distance between the base circle 5b of the cam 5 and the upper end of the valve stem 3a changes due to the thermal expansion of the cylinder head 1 due to the temperature change.
When the distance increases, the adjusting bolt 18 moves downward while rotating by the elastic force of the spring 21 to absorb the change in the distance.

On the other hand, when the cylinder head 1 contracts due to cooling by stopping the engine, and the distance between the valve stem 3a and the base circle 5b decreases, the adjusting bolt 18
The adjusting bolt 18 rotates upward while rotating, and absorbs the change in the distance.

As described above, even if the distance between the base circle 5b of the cam 5 and the upper end of the valve stem 3a changes, the adjusting bolt 18 moves in the axial direction to absorb the change in the distance. An abnormal gap does not occur between the end plates 12 of the lifter body 11 and between the opposed portions of the valve stem 3a and the adjustment bolt 18, so that the valve 3 can be opened and closed accurately.

If the distance between the cam 5 and the valve stem 3a is deviated from the proper distance due to an error in manufacturing or assembling parts, the adjusting bolt 18 is moved in the axial direction while rotating, and the deviation is corrected. It absorbs and prevents an abnormal gap from being formed between the cam 5 and the end plate 12 of the lifter body 11 and between the adjustment bolt 18 and the valve stem 3a.

Here, the valve lifter 10 for adjusting the valve clearance has a structure in which the flange 15 of the nut member 14 is fitted and brazed to the fitting recess 13 formed on the inner surface of the end plate 12 of the lifter body 11. The entire upper surface of the end plate 12 can be effectively used as a cam contact surface.
If the cam lift of the valve lifter shown in FIG.

FIG. 3 shows another example of fixing the nut member 14. In this example, after the flange 15 of the nut member 14 is fitted into the fitting recess 13 formed on the inner surface of the end plate 12 of the lifter body 11, the peripheral edge of the opening of the fitting recess 13 is swaged. . 26 denotes the caulking piece.

As described above, by fixing the nut member 14 by caulking, the nut member 14 can be easily fixed.

[0031]

As described above, according to the present invention, a fitting recess is formed on the inner surface of the end plate of the lifter body, and a nut member with an adjusting bolt screwed into the fitting recess is fitted and fixed. Therefore, a small and compact valve lifter having a short axial length can be obtained, and the entire upper surface of the end plate can be used as a cam contact surface.
The lifter diameter can be used effectively.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a valve gear using a valve lifter according to the present invention.

FIG. 2 is an enlarged sectional view of the same valve lifter;

FIG. 3 is a sectional view showing another example of the valve lifter according to the first embodiment;

FIG. 4 is a sectional view of a valve lifter already proposed.

[Explanation of symbols]

 3a Valve stem 5 Cam 11 Lifter body 12 End plate 13 Fitting recess 14 Nut member 16 Joint layer 17 Screw hole 18 Adjust bolt 21 Spring 26 Caulking piece

Claims (4)

[Claims] 1. A cylindrical lifter body which is assembled between an end of a cam and a valve stem and is slidably supported in an axial direction, a nut member incorporated in the lifter body, and a screw hole of the nut member. An adjusting bolt which is screw-engaged and moves to the valve stem side while rotating by pressing of a spring incorporated in the screw hole, and a fitting recess is provided on an inner surface of an end plate which comes into contact with a cam of the lifter body; A valve lifter of a direct type valve train in which an end of a nut member is fitted and fixed in the fitting recess. 2. The direct type valve train according to claim 1, wherein the fixing is brazing. 3. The direct valve gear according to claim 1, wherein the fixation is caulking of an opening peripheral portion of the fitting concave portion. 4. The flank angle of a pressure side flank receiving an axial pushing force applied from a valve stem to an adjustment bolt is larger than the flank angle of a play side flank. 4. The valve lifter for a direct type valve train according to claim 1, wherein the valve lifter has a sawtooth shape.