JPH1047025A - Valve guide for internal combustion engine and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive compatibility between machinability and abrasion resistance, and also reduce a machining cost, by fitting a guide cylinder formed of a hard material in inner circumferential parts of both end parts in a valve guide main body which is formed of a material having a high heat conductivity and slidably retains the shaft of an engine valve. SOLUTION: A valve guide 2 by which the shaft part 3a of an engine valve 3 is slidably passed through and guided, is pressure-fitted in a cylinder head 1. In this guide 2, while the main body 2a thereof is formed of a material having a high heat conductivity such as a copper alloy, and a guide cylinder 11 formed of an iron hard material having abrasion resistance, is fitted in the inner circumterential parts of both ends parts of the main body 2a so as to be brought into slidable contact with the shaft part 3a. In the thus formed valve guide 2, the guide cylinder 11 is inserted in both end parts in a mold forming an auxiliary shape together with the valve guide 2, and a main body 2a forming material is poured into this guide cylinder 11, thereby the guide cylinder 11 is inserted. At this time, the peripheral surface of the guide cylinder 11 is formed into a taper surface gradually contracted toward an extracting direction, thereby the guide cylinder 11 is prevented from being shipped off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve guide used in a valve train of an internal combustion engine, and more particularly to a valve guide having both machinability and wear resistance and a method of manufacturing the same.

[0002]

2. Description of the Related Art A valve guide is required to have high abrasion resistance in order to guide a reciprocating sliding movement of an engine valve while holding a shaft portion of the engine valve. Therefore, a hard metal such as gray cast iron, alloy cast iron, or a wear-resistant sintered alloy is generally used as a material for the valve guide.

[0003]

The above-mentioned materials having high wear resistance generally have poor machinability (machinability), so that it takes time and effort to finish the shaft hole and the outer peripheral surface, and also to use the cutting material used therefor. The service life of the tool is short, which causes an increase in machining cost.

In addition, since the temperature of the valve guide used on the exhaust side becomes high due to the heat of the exhaust valve, wear tends to occur particularly at the lower end portion near the exhaust port.

To cope with such a problem, it is conceivable that the valve guide is formed of a soft material having a high thermal conductivity instead of the above-mentioned hard metal. The use of degrades abrasion resistance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a valve guide which can achieve both machinability and abrasion resistance while reducing the processing cost, and a method of manufacturing the same. The purpose is.

[0007]

SUMMARY OF THE INVENTION According to the valve guide of the present invention, the above-mentioned object is attained at both ends of a valve guide body which is formed of a material having high thermal conductivity and slidably holds a shaft of an engine valve. The problem is solved by fitting a guide cylinder made of a hard material to the inner peripheral portion so as to be able to slide on the outer peripheral surface of the shaft portion. Further, according to the manufacturing method of the present invention, the above-mentioned problem is solved as follows.

(1) After inserting a pair of guide cylinders made of a hard material capable of holding an outer peripheral surface of a shaft portion of an engine valve into both ends of a mold which is complementary to a valve guide to be manufactured, A molten material having a high thermal conductivity is poured into the mold, and the two guide cylinders are cast.

(2) In the above item (1), the outer peripheral surface of the guide cylinder is a rough surface or a tapered surface whose diameter gradually decreases in the exit direction.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a valve operating mechanism to which the present invention is applied. An up-down valve guide (2) press-fitted into a cylinder head (1) has an engine valve.
The shaft part (3a) of (3) is slidably penetrated and held.

The valve face (3c) of the umbrella (3b) connected to the lower end of the engine valve (3) comes into contact with the valve seat (5) fitted to the lower end of the opening of the port (4), Always a port
(4) is closed.

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 end of (9) presses the upper end of the engine valve (3) to open and close it.

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

In the valve guide (2) of the present invention, the main body (2a) is formed of a material having a high thermal conductivity such as a copper alloy or an aluminum alloy. Guide tube made of iron-based hard material
(11) is fitted in sliding contact with the shaft (3a) of the engine valve (3).

Such a valve guide (2) can be easily formed, for example, by casting. That is, although not shown, the guide cylinders (11) and (11), which have been finished to predetermined dimensions in advance, are inserted into both ends of a mold that complements the valve guide (2) to be manufactured, and the main body ( 2a) If the molten material for molding is poured into the mold, both guide cylinders (11) are integrally cast into the main body (2a).

At this time, the outer peripheral surface of the guide cylinder (11) is formed with a jagged or spiral rough surface (12) as shown in FIG. 2 or is directed outward (outward direction) as shown in FIG. If it is set as a tapered surface (13) that gradually reduces the diameter of the engine valve,
By the sliding motion of the shaft (3a) of (3), the guide cylinder (11) is
(2a) There is no risk of falling off. In addition to the rough surface (12) and the tapered surface (13), a simple projection may be used.

The reason why the rigid guide cylinder (11) is provided only at the inner peripheral portions at both ends of the main body (2a) is as follows.

That is, during operation of the engine, the load acting on the valve guide (2) is a radial pressing force mainly based on a bending load acting on the shaft portion (3a) of the engine valve (3). This is because the force largely acts on both ends of the valve guide (2). Therefore, it is sufficient to provide high wear resistance only to both ends, and if a material having a high thermal conductivity is used for the other parts, the material is relatively soft, so that finishing work is performed. The machinability at the time of applying is improved, the life of the cutting tool or the like is extended, and the machining cost is reduced.

Moreover, since the thermal conductivity to the cylinder head (1) is improved, when the valve guide (2) of the above embodiment is used on the exhaust side, not only the valve guide (2) but also the engine valve (2) is used. The cooling effect of 3) is large, and the sliding surfaces of each other are less likely to be worn.

The guide tube (11) may be detachably mounted on the main body (2a) with screws or the like so that only the guide tube (11), which is liable to wear, can be replaced.

[0022]

According to the valve guide of the present invention, since the hard guide cylinders are fitted to the inner peripheral portions at both ends of the valve guide main body made of a material having high thermal conductivity, machinability is improved. In addition, it is possible to improve the abrasion resistance of a part where abrasion is most likely to occur.

Further, since the thermal conductivity to the cylinder head is improved, the cooling effect of the valve guide and the engine valve is increased, and the sliding surfaces of the valve guide and the engine are less likely to be worn.

According to the method of the second aspect, a valve guide having both machinability and wear resistance can be easily manufactured.

According to the third aspect, the guide cylinder can be prevented from coming off due to the sliding movement of the engine valve.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of a valve train equipped with a valve guide according to the present invention, taken along a central longitudinal section.

FIG. 2 is an enlarged vertical sectional front view of a main part showing a state in which a jagged rough surface is formed on an outer peripheral surface of a guide cylinder in a valve guide.

FIG. 3 is an enlarged vertical sectional front view of a main part showing a state where the outer peripheral surface of the guide cylinder is a tapered surface.

[Explanation of symbols]

 (1) Cylinder head (2) Valve guide (2a) Main body (3) Engine valve (3a) Shaft (3b) Head (3c) Face (4) Port (5) Valve seat (6) Spring retainer (7 ) Valve spring (8) Rocker arm (9) Adjuster bolt (10) Lip seal (11) Guide cylinder (12) Rough surface (13) Tapered surface

Claims (3)

[Claims] 1. A material formed of a material having high thermal conductivity.
A guide cylinder made of a hard material is fitted to inner peripheral portions of both ends of the valve guide body that holds the shaft portion of the engine valve so as to be slidable so as to be able to slide on the outer peripheral surface of the shaft portion. Valve guide for an internal combustion engine. 2. A pair of guide cylinders made of a hard material capable of holding an outer peripheral surface of a shaft portion of an engine valve are inserted into both ends of a mold which is complementary to a valve guide to be manufactured. A method for manufacturing a valve guide for an internal combustion engine, comprising: pouring a molten material having high thermal conductivity into a mold; and casting the both guide cylinders. 3. The method for manufacturing a valve guide for an internal combustion engine according to claim 2, wherein the outer peripheral surface of the guide cylinder is a rough surface or a tapered surface whose diameter is gradually reduced in a pull-out direction.