JPH0861026A - Engine valve spring retainer - Google Patents

Abstract

PURPOSE: To prevent the damage of a spring retainer by making uniform the stress distribution of a tapered hole in a spring retainer fitted closely onto a cotter and reducing an excessive stress generated at the end on the small diameter side of a tapered hole. CONSTITUTION: The angle α1 of a tapered hole 4a in a spring retainer 4 is made slightly smaller than the tapered angle α2, of the outer surface 3b of a cotter 3 so as to uniform the stress distribution of the inner surface of a tapered hole 4a, prevent stress concentration on the small diameter side, and also prevent the damage of the spring retainer 4 from a small diameter opening part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine valve spring retainer which is engaged with a shaft portion of an engine valve via a cotter so as to receive one end of a valve spring.

[0002]

2. Description of the Related Art FIG. 2 schematically shows a main part of a conventional engine valve mechanism, and an annular groove (2) cut near the end of a shaft part (1a) of an engine valve (1). An inwardly projecting ridge (3a) formed on the inner surface of a pair of left and right cotters (3) having a half-cylindrical shape is externally fitted therein. The outer surface (3b) of the cotter (3) is a tapered surface, and a taper hole (4a) having the same taper angle as the outer surface (3b) is formed in the center of the spring retainer (4). The taper hole (4a) is formed on the outer surface (3) of the pair of cotters (3).
The spring retainer (4) is locked to the shaft portion (1a) of the engine valve (1) by being externally fitted to b).

Tapered hole in spring retainer (4)
A coil-shaped valve spring (5) is contracted between the surface of (4a) on the small-diameter opening side, that is, between the lower pressure-receiving surface (4b) and the cylinder head (not shown) below it, and the engine valve ( 1) is always biased upward through the spring retainer (4). Reference numeral (6) is a rocker arm that pushes down the engine valve.

[0004]

The taper angle of the taper hole (4a) of the above-mentioned conventional spring retainer (4) is cotter.
It is matched with the taper angle of the outer surface (3b) of (3). Therefore, the stress generated in the tapered hole (4a) of the spring retainer (4) gradually increases from the large diameter side to the small diameter side of the tapered hole (4a) as shown in the stress distribution (a) on the right side of FIG. However, there is a problem that the end on the small diameter side becomes maximum, and excessive stress at this point becomes a starting point of spring retainer failure.

The object of the present invention is to make the stress distribution of the taper hole of the spring retainer fitted on the cotter uniform and reduce the over stress generated at the end of the taper hole on the small diameter side, thereby preventing the spring retainer from being damaged. To prevent.

[0006]

According to the present invention, the above problems can be solved as follows. (1) Fit the tapered hole drilled in the center to the tapered outer surface of the cotter attached to the outer periphery of the engine valve shaft,
In an engine valve spring retainer in which the surface of the tapered hole on the small diameter opening side is used as a pressure receiving surface for receiving the end portion of the valve spring, the taper angle of the tapered hole is made slightly smaller than the taper angle of the outer surface of the cotter.

(2) In the above item (1), the taper angle of the tapered hole is made smaller than the taper angle of the cotter by a negative tolerance.

[0008]

According to the present invention, the stress distribution in the taper hole of the spring retainer during valve operation is made substantially uniform, and stress is not concentrated on the small diameter opening side of the taper hole.
The risk of breakage can be reduced compared to the conventional spring retainer.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention and is an enlarged view of a portion similar to that of the conventional example of FIG. The same members and parts as those in the conventional example in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

The cotter (3) is exactly the same as the cotter in FIG. 1 and has an outer surface (3b) which is a tapered surface. A taper hole (4a) formed in the center of the spring retainer (4) is fitted on the outer surface (3b) of the pair of cotters (3) in the shape of a half cylinder.

According to the invention, the spring retainer (4)
The taper angle α1 of the taper hole (4a) of the
It is slightly smaller than the taper angle α2 of (3b). Therefore, when the tapered hole (4a) of the spring retainer (4) and the tapered surface (3a) of the cotter (3) are fitted, the fitting force is strong on the large diameter side and weak on the small diameter side. Therefore, the stress on the large diameter side and the stress on the small diameter side are substantially uniform as shown by the imaginary stress distribution (b) in FIG. 3, and the maximum stress on the small diameter side is reduced.

The taper hole (4) of the spring retainer (4)
It is preferable that the taper angle α1 in a) be calculated back from the strain amount by FEM analysis and be smaller than the negative tolerance of the set tolerance of the taper angle of the cotter (3). Specifically, -10'-
-20 'is preferable.

[0013]

According to the present invention, by making the taper angle of the taper hole of the spring retainer slightly smaller than the taper angle of the outer surface of the cotter, the stress distribution of the taper hole during valve operation can be made substantially uniform. It is possible to prevent the maximum stress from being generated on the small diameter side of the taper hole, and thereby to eliminate the risk of damage to the spring retainer that has been generated over the years.

According to the second aspect of the present invention, the taper angle of the taper hole is set to be smaller than the taper angle of the cotter by a negative tolerance, so that the ideal stress distribution shown in FIG. b) is obtained or it can be approached infinitely.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a taper hole of a spring retainer according to an embodiment of the present invention fitted to an outer surface of a cotter, in which a taper angle difference between the taper hole and the outer surface of the cotter is exaggerated. FIG.

FIG. 2 is a central vertical sectional front view of a valve mechanism including a conventional spring retainer.

FIG. 3 is a diagram showing an enlarged vertical cross-section of the main part and stress distribution in the tapered hole.

[Explanation of symbols]

 (1) Engine valve (1a) Shaft part (2) Annular groove (3) Cotta (3a) Inward projection (3b) Outer surface (4) Spring retainer (4a) Tapered hole (4b) Pressure receiving surface (5) Valve Spring (6) Rocker arm (α1) Taper angle of taper hole (α2) Taper angle of cotter outer surface

Claims (2)

[Claims] 1. A taper hole formed in the center is fitted to a tapered outer surface of a cotter that is engaged with the outer periphery of the shaft portion of an engine valve. An engine valve spring retainer having a pressure receiving surface for receiving an end portion, wherein a taper angle of the taper hole is slightly smaller than a taper angle of an outer surface of the cotter. 2. The engine valve spring retainer according to claim 1, wherein the taper angle of the taper hole is smaller than the taper angle of the cotter by a negative tolerance.