JP2578369Y2 - Valve lifter - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a valve lifter.
More specifically, the present invention relates to a valve lifter used in an overhead cam (OHC) system in which a valve stem is directly driven by a cam from directly above an intake / exhaust valve of an engine.

[0002]

2. Description of the Related Art Conventionally, a valve mechanism of this type using an overhead cam system has excellent performance such as good followability and high natural frequency, which is suitable for a high-speed engine. Is difficult to adjust,
In recent years, various measures and proposals have been made for such a problem.

For example, Japanese Unexamined Utility Model Publication No. 63-98408 discloses a valve lifter for an internal combustion engine having an OHC type valve mechanism, which is made of a light alloy and has a concave portion in a crown surface corresponding to the top. The disk-shaped shim is formed and fitted into the recess in a loose fit. That is, by adjusting the thickness of the shim, no inconvenience occurs when the valve is opened and closed.

[0004]

However, in such a conventional example, inconveniences such as inconsistency and deviation of the processing accuracy between the concave portion forming surface and the shim fitting surface tend to occur. Has the following disadvantages.

That is, if the flatness of the concave portion formed on the crown surface of the valve lifter is not sufficient, or if there is a tendency of inclination or middle height, the shim fitted into the concave portion may rise or tilt from the bottom surface of the concave portion. And a stable fit cannot be maintained. For this reason, the shim swings, that is, flutters in the concave portion in accordance with the movement of the sliding position of the shim that comes into sliding contact with the cam along with the rotation of the cam, which causes noise.

SUMMARY OF THE INVENTION An object of the present invention is to provide a valve lifter suitable for an OHC type valve mechanism in which a stable shim can be obtained in order to solve the conventional problems.

[0007]

A valve lifter according to the present invention which can achieve the above object is incorporated in a valve operating mechanism of an intake / exhaust valve, and is provided between a driving cam and a driving cam. the recess depth increases gradually toward the central portion is provided, the outer shim the lower surface peripheral edge portion of the outer <br/> shim which forms a disc-shaped tailored fit the recess in the state of being supported on the peripheral portion of the recess None of the top surface so as to contact the drive cam, wherein at the maximum lift of the intake and exhaust valves Au
Is characterized in that during deflection of the motor shim was set to a gap in the central portion between the lower surface and the recess of the Autashimu is maintained.

[0008]

According to the present invention, the contact position between the drive cam and the outer shim changes with the rotation of the drive cam, and the outer shim is elastically deformed in the direction facing the bottom surface of the concave portion. A gap is always maintained between the outer shim and the periphery of the lower surface of the outer shim and the periphery of the concave portion provided on the crown surface of the valve lifter are always in stable contact with each other. For this reason, the pressing force by the drive cam is transmitted to the valve lifter from the peripheral edge of the lower surface of the outer shim through the peripheral portion of the concave portion.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which (A) shows a state when the valve mechanism is opened, and (B) shows a state when the valve is closed. In FIG. 1, 1 is an intake / exhaust valve, 1
A is a stem, 2 is a valve lifter held at the end of the stem 1A via an inner shim 3, and 4 is a shim fitted to the crown recess 2A of the valve lifter 2 (hereinafter referred to as an outer shim to distinguish it from the inner shim 3). is there.
The valve stem 1A is slidably held along a valve guide 6 provided on the cylinder head 5.
A spring retainer 7 is fixed near the top of the stem 1A, and the valve lifter 2 and the outer shim 4 are attached to the cam surface of the cam 10 by the elastic force of the valve spring 9 held between the lower spring seat 8 and the retainer 7. Biased toward.

In the present embodiment, the body of the valve lifter 2 is formed of an aluminum alloy, and its surface is plated with a nickel-phosphorus alloy (Kanigen-registered trademark) to provide particularly corrosion resistance, wear resistance and the like. Improve it. Further, as shown in FIG. 1A, the crown concave portion 2A of the valve lifter 2 is formed as a spherical concave surface having its center at the bottom, and between the concave surface and the bottom surface of the outer shim 4. Utilizing the kept concave space 11, unstable behavior of the outer shim can be prevented. Here, the outer shim 4 has been subjected to carburizing treatment of carbon steel in order to impart elasticity and wear resistance (JIS standard SCM41).
5H) was used.

The operation of the valve mechanism according to the above embodiment will be described below with reference to FIGS. 1 (A) and 1 (B).

In the present embodiment, when the valve 1 is in a closed state in contact with the valve seat 12 as shown in FIG. 1A, the outer shim 4 in which the circular portion 10A of the cam 10 is fitted into the crown recess 2A of the valve lifter 2. It is adjusted to keep the contact lightly on the upper surface of. Therefore, in this state, the peripheral edge of the outer shim 4 is held by the peripheral corners of the crown recess 2A, so that the concave space 11 is maintained as shown in FIG. Even if a force that pushes the valve 1 to the outer shim 4 through the stem 1A acts on the outer shim 4 through the stem 1A due to wear or the like, the space 11 is buffered and the outer shim 4 is only slightly bent.

Then, from the state shown in FIG. 4A, the rotation of the cam 10 causes the convex surface portion 10B to press the valve lifter 2 via the outer shim 4 to open the valve 1 against the elastic force of the spring 9. When the state shifts to the state (B), the outer shim 4 bends in this manner in the form of a hollow. In this case, even when the valve opening is at the maximum as shown in FIG.
By setting such that some space 11 is reserved between the center of the lower surface of the outer shim 4 and the lowermost portion of the crown recess 2A, the outer shim is regulated so as not to perform harmful behavior. Can be.

[0015]

According to the valve lifter of the present invention, a concave portion whose depth gradually increases from the peripheral portion toward the central portion is provided on the crown surface of the valve lifter, and the lower peripheral portion of the outer shim in the form of a disc fitted to the concave portion. The drive cam is brought into contact with the upper surface of the outer shim while supporting the outer shim on the periphery of the concave portion, so that a gap is always maintained between the lower surface of the outer shim and the concave portion. As a result, it is possible to suppress the generation of the impact noise as in the related art, and to alleviate the unnecessary force acting on the valve lifter.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the configuration and operation of a valve lifter of the present invention in a closed state (A) and an open state (B).

[Explanation of symbols]

 Reference Signs List 1 valve 1A (valve) stem 2 valve lifter 2A crown recess 3 inner shim 4 outer shim 9 valve spring 10 cam 10A circular part 10B convex part 11 (concave) space 12 valve seat

Claims (1)

(57) [Scope of request for utility model registration] 1. A valve lifter incorporated in a valve operating mechanism of an intake / exhaust valve and provided between a drive cam and a drive cam, wherein a concave portion whose depth gradually increases from a peripheral portion toward a central portion is provided on a crown surface thereof. No such contacting said drive cam on the upper surface of the outer shim in a state that the lower surface peripheral edge portion of the outer shim forming the mating discoid was supported around portion of the recess, the maximum lift of the intake and exhaust valves valve lifter, characterized in that as the gap is maintained at the central portion between the lower surface and the recess of the Autashimu upon deflection of the outer sheet <br/> beam during.