JPH1047024A - Engine valve retaining structure in cylinder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the length of a guide member, and facilitate the machining of the guide member, by forming a shaft hole in a cylinder head so that the center part of the shaft part of an engine valve is passed through, and fitting between both upper and lower ends of this shaft hole, the abrasive resistant guide member by which the upper and lower part of the center part of the shaft part are slidably retained. SOLUTION: A shaft hole 11 through which the center part of the shaft part 3a of an engine valve 3 is passed, is formed in a vertical direction in a cylinder head 1, and both upper and lower end parts of the shaft hole 11 are formed into diameter enlarged holes 11a. Then, short guide members 12 formed of a hard member such as alloyed cast iron and an abrasive resistant sintered alloy, are respectively pressure- fitted in the upper and lower diameter enlarged holes 11, and the upper and lower parts of the center part in the shaft part 3a of the engine valve 3 are slidably retained and guided by the guide members 12. The inside diameter of the shaft hole 11 between the upper and lower guide members 12, is formed a little bit larger than the outside diameter of the shaft part 3a, so that a little bit clearance is formed against the shaft part 3a or the shaft part 3a is lightly brought into contact with the shaft hole 11, and the shaft part 3a is substantially guided by the upper and lower guide members 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure for holding an engine valve in a cylinder head, which slidably holds and guides the shaft of the engine valve.

[0002]

2. Description of the Related Art FIG. 2 schematically shows an example of a valve operating mechanism of an internal combustion engine. An up-down valve guide (2) press-fitted into a cylinder head (1) has an engine valve (3). Is slidably penetrated and held.

[0003] A valve face portion (3c) of an umbrella portion (3b) connected to a lower end of the engine valve (3) comes into contact with a valve seat (5) fitted to the lower end of the opening of the port (4). Always a port
(4) is closed.

[0004] A spring retainer (6) is fixed to the upper end of the engine valve (3) via a pair of cotters (not shown). A valve spring (7) is contracted between the spring retainer (6) and the cylinder head (1),
As a result, the engine valve (3) is constantly urged upward.

An adjuster bolt screwed to the tip of a rocker arm (8) which is swung up and down by a cam (not shown)
The lower surface of (9) presses the upper end of the engine valve (3) to open and close it.

[0006] Reference numeral (10) denotes a lip seal for preventing oil falling, which is fitted to the upper end of the valve guide (2).

The normal valve guide (2) used in such a valve operating mechanism is formed relatively long, and guides the shaft (3a) of the engine valve (3) in the entire area. For this reason, the valve guide (3) is formed using a hard material such as gray cast iron or alloy cast iron so as to enhance the wear resistance of the entire shaft hole.

[0008]

The above-mentioned hard materials have poor machinability (machinability), so that the valve guide
It takes time and effort to machine the shaft hole and the outer peripheral surface of (3), and the life of the cutting tool used for it is short, resulting in an increase in machining cost.

The present invention has been made in view of the above-mentioned problems, and the reason why a large load acts on the engine valve is as follows.
Focusing primarily on both ends of the valve guide, the dimensions were minimized and fitted to the cylinder head, so that the processing cost could be greatly reduced.
It is an object of the present invention to provide a structure for holding an engine valve in a cylinder head.

[0010]

According to the present invention, the above-mentioned problem is solved as follows. (1) An abrasion resistance in which a center hole of a shaft portion of an engine valve is formed in a cylinder head and upper and lower ends of the shaft hole are slidably held at upper and lower ends of the shaft hole. The guide member is fitted.

(2) In the above item (1), the inner diameter of the shaft hole between the two guide members is set to a size that allows light contact with the shaft portion.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The same members as those in the above-described conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted. In FIG. 1, the cylinder head (1) has a shaft hole (11) through which the center of the shaft (3a) of the engine valve (3) passes.
However, it is formed so as to face in the up-down direction, and the upper and lower ends are formed as diameter-enlarging holes (11a). A part of the upper diameter expanding hole (11a) is formed in an upwardly extending annular bulging portion (1a) formed on the upper surface of the cylinder head (1).

Short guide members (12) (12) formed of hard materials such as gray cast iron, alloy cast iron, and wear-resistant sintered alloy are press-fitted into the upper and lower enlarged holes (11a), respectively. And
The upper and lower portions of the central portion of the shaft portion (3a) of the engine valve (3) are slidably held and guided.

The inner diameter of the shaft hole (11) between the upper and lower guide members (12) is slightly larger than the outer diameter of the shaft portion (3a).
A slight gap is formed with respect to the shaft portion (3a), or the shaft portion (3a) comes into light contact. Accordingly, the shaft portion (3a) is substantially held and guided by the upper and lower guide members (12).

During the operation of the engine, the load acting on the valve guide mainly depends on the engine valve.
This is a radial pressing force based on a bending load acting on the shaft portion (3a) of (3), and this force largely acts on both ends of the valve guide.

Therefore, as in the above-described embodiment, a short, wear-resistant short dimension is provided at both ends of the shaft hole (11) through which the shaft (3a) of the engine valve (3) in the cylinder head (1) passes. It is enough to press-fit the guide members (12) and (12), thereby holding and guiding the center part of the shaft part (3a) up and down, and it is necessary to use a long valve guide as in the past. There is no.

As a result, the machining of the guide member (12) is facilitated, the life of the cutting tool used for the guide member is prolonged, and the machining cost is reduced. Also, if the middle portion of the shaft hole (11) is lightly contacted with the shaft portion (3a) to the extent that abrasion does not occur, heat radiation to the cylinder head (1) side is improved, and the shaft portion (3a) is The cooling effect increases.

[0018]

According to the present invention, only the upper and lower portions of the central portion of the shaft portion of the engine valve on which a large bending load acts are held by the guide member, so that the length of the guide member can be minimized. , And its processing becomes easier,
The life of the cutting tool is extended, and the machining cost is greatly reduced.

According to the second aspect, since the shaft portion comes into direct contact with the cylinder head, the cooling effect is enhanced.

[Brief description of the drawings]

FIG. 1 is a vertical front view in the center of a valve train to which the present invention is applied.

FIG. 2 is a central longitudinal sectional front view showing a conventional example.

[Explanation of symbols]

 (1) Cylinder head (1a) Annular bulge (2) Valve guide (3) Engine valve (3a) Shaft (3b) Head (3c) Valve face (4) Port (5) Valve seat (6) Spring retainer (7) Valve spring (8) Rocker arm (9) Adjuster bolt (10) Lip seal (11) Shaft hole (11a) Large diameter hole (12) Guide member

Claims (2)

[Claims] An abrasion-resistant bore formed in a cylinder head through which a central portion of a shaft portion of an engine valve penetrates, and upper and lower ends of the shaft portion are slidably held at upper and lower ends of the shaft hole. A holding structure for an engine valve in a cylinder head, wherein a flexible guide member is fitted. 2. The structure for holding an engine valve in a cylinder head according to claim 1, wherein the inner diameter of the shaft hole between the two guide members is set to a size capable of lightly contacting the shaft portion.