JPH0267406A - Valve guide of internal combustion engine and manufacture thereof - Google Patents

Abstract

PURPOSE:To aim at the reduction of cost and weight and improvement in heat conductivity by forming an intermediate member of a specific metal in comparison with a sintered alloy of both end members, and making the intermediate member occupy a specific ratio in the full length of a valve guide shaft, while making the same engage with a stage-shaped cross section with respect to both the end members. CONSTITUTION:Both end members 1 are formed of a sintered alloy provided with an abrasion resistance property comprising either an iron system or a copper system. On the other hand, an intermediate member 2 is formed with a metal material which is applicable to at least one or more of a member of which ductility is a larger than the sintered alloy, a member of which heat conduction property is a better than it, and a poor composition member. In a valve guide for an internal combustion engine formed with a combined structure like this, the shaft direction length of the intermediate member 2 is set at 30% to 60% in the total length of the valve guide. Further, both the end members 1 and the intermediate member 2 are engaged at a stage-shaped cross surface so as to compactly be fitted each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve guide for an internal combustion engine having a composite structure consisting of three layers in the axial direction, and a method for manufacturing the same.

(Prior art) Valve guides for internal combustion engines such as automobiles usually use a sintered alloy, and the axial length of these valve guides is about 4 to 8 times the inner diameter, and the material as,
An iron-based or copper-based sintered alloy having the same composition as a whole is used, and is made by a normal powder metallurgy method and used by cutting.

(Problems to be Solved by the Invention) This type of valve guide for an internal combustion engine has a long axial dimension relative to its diameter, so the powder filling depth of the molding mold is large, making it difficult to mold it with high density. Therefore, problems have been pointed out, such as the molded bodies tend to fall over during transportation and cracks occur.

Furthermore, there are various demands for valve guides for internal combustion engines, such as low cost, good thermal conductivity and easy heat dissipation, and light weight.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a valve guide for an internal combustion engine that is low cost, has good heat conduction, is easy to dissipate heat, and can greatly contribute to weight reduction. The purpose is to provide a manufacturing method.

(Means for Solving the Problems) In order to achieve the above object, the valve guide for an internal combustion engine according to the present invention has both end members made of either iron-based or copper-based sintered joints with wear resistance. The intermediate member is made of gold, and the intermediate member is made of a metal material that has at least one of the following: a member with greater ductility, a member with better thermal conductivity, and a member with a poorer composition than the sintered alloy. A valve guide for an internal combustion engine having a composite structure, wherein the axial length of the intermediate member accounts for 30 to 60% of the total length of the valve guide,
It is characterized in that both end members and the intermediate member interlock with each other with stepped cross sections and are joined by an interference fit.

Furthermore, in the above method for manufacturing a valve guide for an internal combustion engine, both end members are made of a wear-resistant sintered alloy made of either iron or copper, and the intermediate member is made of the above-mentioned sintered alloy. Also, in the method for manufacturing a valve guide for an internal combustion engine having a composite structure, the intermediate member is made of a metal material that meets at least one of the following: a member with high ductility, a member with good thermal conductivity, and a metal material with poor composition. The inner diameter or outer diameter is removed in a stepped manner, the outer diameter or inner diameter of both end members is tapered, and the axial length thereof is set shorter than the stepped length of the intermediate member, and when both are fitted, By inserting it into the sizing mold and pressing it downward with a punch, the thin end surface of the intermediate member is plastically deformed, filling the gap between both end members and the intermediate member, and the member is pushed down in the radial direction, reducing the cross-sectional area. Due to this reduction, the fitting portions of both members are tightly interlocked, compressed from the axial and radial directions, and stretched in the axial direction.

(Function) According to the above means, the intermediate member is made of one or more of the following metals: a member with greater ductility, a member with good thermal conductivity, and a metal with poor composition than the sintered alloy at both ends. At the same time, it occupies 30 to 60% of the total length of the valve guide in the axial direction, and since both end members and the intermediate member are interlocked with a stepped cross section and are tightly fitted together, it meets the requirements for improving valve guides for internal combustion engines. , it becomes possible to achieve weight reduction and improved thermal conductivity.

Furthermore, the above valve guide for an internal combustion engine can be manufactured easily by using a sizing mold having a special mold shape.

(Example) Hereinafter, a valve guide for an internal combustion engine and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows an example of the cross-sectional structure of a material showing a valve guide for an internal combustion engine having a composite structure according to the present invention.
The both end members 1 and the intermediate member 2 have a stepped structure in which the cross section is double-shaped and interlocks with each other. Furthermore, each side of this material is processed before it is installed in the internal combustion engine.

By the way, the above-mentioned valve guide is used in a high-temperature environment close to the combustion chamber, and requires good compatibility with the mating valve and wear resistance, so the sliding surfaces near the ends, where blood pressure tends to be particularly high, are subject to wear. This requires the use of materials that are easy to use and have high density.

In the present invention, both end members 1 of the valve guide are made of a sintered alloy. From the above point of view, this sintered alloy is preferably a high-density sintered alloy in which a solid lubricant is dispersed, and iron-based sintered alloys are often used in internal combustion engines for passenger cars. For example, those with a composition containing copper, tin, phosphorus, and 1.5 to 4% carbon (composition disclosed in Japanese Patent Publication No. 55-34858), copper-based ones are used as valve guides for outboard motors, etc. This applies to materials such as phosphor bronze alloy-based materials in which solid lubricants are dispersed.

In addition, the both end members 1 are easy to handle due to their short molded length, and can be molded with high density, and the density can be further increased by plastic processing when joining each member, which will be described later. .

Next, the intermediate member 2 can be made of various metal materials depending on requirements, but metals with low specific gravity or alloys thereof are used to reduce the weight. For example, when both end members 1 are made of iron-based sintered alloy, the intermediate member 2 is made of aluminum alloy, and when both end members 1 are made of copper-based sintered alloy, intermediate member 2 is made of steel or aluminum alloy. Ru.

Furthermore, this intermediate member 2 may be made of either a melted material or a sintered material.

Next, regarding the thermal conductivity of the intermediate member 2, when an iron-based sintered alloy is used as the both end members 1, copper or bronze and aluminum alloy may be used as the intermediate part 42; Similar effects can be obtained with either binding material.

Furthermore, in terms of price, general-purpose sintered materials or both end members 1
A sintered material with a poor composition of a copper-based alloy may be selected as the intermediate member 2, but molten materials tend to be expensive due to the high cost of processing them into a cylindrical shape. In iron-based and copper-based sintered alloys, - iron-carbon-based or iron-copper-carbon-based sintered alloys in the film, aluminum-silicon-
Copper-based sintered alloys, etc. can be used.

Moreover, among the above-mentioned combinations of materials, there are some that can meet a plurality of requirements. That is, when both end members 1 are made of iron-based sintered alloy, if aluminum alloy is used as the intermediate member 2, all aspects of weight reduction, thermal conductivity, and cost can be met.

Next, the axial lengths of both end members 1 are approximately equal, and the length of the intermediate member 2 is 30 to 66% of the total length of the valve guide.
A range of 0% is preferable, and if the length of the intermediate member 2 is less than 30%, the effect is slight, and the axial joint surface when joining each member becomes short, resulting in insufficient joint strength. Conversely, if the length of the intermediate member 2 is set longer than 60% of the total length, the effect will be greater, but the length of the end member 1 will be shorter, the axial joint surface will be shorter, and the durability will be reduced. Abrasion resistance is disadvantageous.

Next, a method for manufacturing a valve guide for an internal combustion engine according to the present invention will be briefly described with reference to FIGS. 2 and 3.

FIG. 2 shows a sizing mold device for explaining the sizing method. In this figure, a punch 4 and a die guide 6 are fixed to a ram 3 that moves up and down, and a die 9 with a medium-sized inner diameter is fitted with the die guide 6 and is urged downward by a spring 8. has been done.

On the other hand, the core 5 has a large outer diameter at the middle portion, and fits into the blind hole formed by the bed 7 and the inner diameter of the punch 4, and is not fixed.

Note that FIG. 2 shows the ram 3 at the bottom dead center.

FIG. 3 is an enlarged cross-sectional view of the joint portion between both end members 1 and the intermediate part 2. The intermediate member 2 has a shape in which the inner diameter or outer diameter is removed in steps, and is harder than the intermediate member 2. Both end members 1 having high toughness have a tapered outer diameter or inner diameter at the joint portion, and have an axial length shorter than the step length of the intermediate member 2.

Further, the volumes of the gap a having a triangular cross section and the end face gap are set to be approximately equal when they are fitted together.

Note that the thin end surface portion 2a of the intermediate member 2 may be on the outer diameter side as shown in FIG. 1, but in the case of a combination of materials in which the coefficient of thermal expansion of the intermediate member 2 is larger than that of both end members 1, the bonding force will be reduced. Therefore, it is important to set it on the inner diameter side.

When the stepped parts of each member 1.2 are inserted into the sizing mold shown in FIG. 2 and pushed downward with the punch 4, the thin end surface 2a of the intermediate member 2 will be plastically deformed. , while the gap a decreases, the gap also decreases, and finally the gap a,
Both b disappear.

On the other hand, in the radial direction, members 1 and 2 are pushed down and the cross-sectional area is reduced, so that the fitting portions of each member 1 and 2 are tightly interlocked, and the sintered material is compressed from the axial and radial directions, resulting in the density of the sintered material. is raised and the member 1.2 is stretched in the axial direction.

In addition, the axial length of the occlusal part is preferably 2 to 5 mm. If it is too short, the fastening will be insufficient, and if it is too long, the thin end surface portion 2a may buckle during pressurization.

The area reduction rate varies somewhat depending on the dimensions of the valve guide and the material used, but it is 10 to 30%, and usually about 15% is preferable. Further, it is necessary to consider that the axial dimension after joining will be longer than before joining. When the area reduction rate is 15%, sintered material has a reduction of 8 to 9%, and melted material has a reduction of approximately 1.
7% longer.

If the sintered material has a copper-based composition, the both end members 1 and the intermediate member 2 can be joined by stacking and filling raw material powder during molding and pressing.
Sintering can be used, but if the amount of change in sintered dimensions is different, steps may be formed or cracks may occur at the joint, and sintering is not possible when dissimilar metals are used. In addition, brazing has the disadvantage of being difficult to mass-produce, whereas the compression interlocking method of the present invention allows a strong joint to be obtained even with dissimilar materials, and is also favorable for mass-productivity.

Specific examples 1 to 3 will be described in detail below.

Example 1 This example is lightweight, and uses a phosphor bronze sintered alloy for both end members and a molten aluminum alloy for the intermediate member.

The phosphor bronze sintered alloy has a composition of 2.7%Ni-3%P-4
．． It is phosphor bronze with 5% molybdenum disulfide and has a density of 7.
The outer diameter of the joint was cut into a tapered shape with an axial length of 4 mm at a pressure of 1 g/=.

On the other hand, the aluminum alloy was made by cutting a bar material of alloy number 2024, and the inner diameter was fitted to both end members with a gap between the end faces as shown in FIG. The dimensions of each member are 7 mm in inner diameter and 10 mm in outer diameter.In the axial direction, the total length after joining is 50 mm, and the intermediate member is 25 mm (50% of the total length).
). In addition, the reduction rate of the member cross section during extrusion processing is 1
It was set at 5%.

The weight of the resulting composite valve guide material is about 5% less than that of a case where the entire material is made of phosphor bronze sintered alloy. Further, the density of the double-ended phosphor bronze sintered alloy increased to 7.7 g/cJ.

Example 2 This example is an example in which high thermal conductivity was improved, and
An iron-based sintered alloy containing free graphite is used for both end members, and a bronze sintered alloy is used for the intermediate member.

Iron-based sintered alloy is iron and 3%C-3%C1-1%5n-Q
It has a composition of 2% P and a density of 6.6 g/ai'.

The bronze sintered alloy uses a material with a composition of 5% Sn and a density of 6.9 g/d. The dimensions and joining method are the same as in Example 1, but the difference is that the thin portion of the intermediate member is set on the inner diameter side.

The end density of the joined valve guide material is 7.1 g/c
nf, the density of the middle part is 7.4 g/cm', and the thermal conductivity (VLm-'・K-1) of each member is 80 for the iron-based shrine at the end and 150 for the bronze material at the middle part. .

Example 3 This example aims at cost reduction, and uses a phosphor bronze sintered alloy for both end members and an iron-carbon based sintered alloy for the intermediate member.

The phosphor bronze sintered alloy is the same as in Example 1, and the iron-carbon based sintered alloy has a composition of 0.4% C and a density of 6.6 g/af. The dimensions, shape and joining method are the same as in Example 1. With this configuration, the manufacturing cost of the valve guide material can be reduced by 5% compared to the case where only phosphor bronze sintered alloy is used.

(Effects of the Invention) As explained above, the composite structure valve guide for an internal combustion engine according to the present invention has improved performance (
It is possible to provide a valve guide for an internal combustion engine that has high practical value such as improved thermal conductivity, reduced weight) and reduced cost.

Furthermore, in the present invention, the materials of both end members and the intermediate member are changed, the joint part is made into a special shape, and it can be easily manufactured using a special-shaped mold, so that it has high practical value.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a valve guide for an internal combustion engine according to the present invention, Fig. 2 is a sectional view showing a mold device for joining both end members and an intermediate member of the valve guide, and Fig. 3 is a sectional view of the valve guide. FIG. 3 is a cross-sectional view showing the stepped shape of the joint portion of FIG. 1...Both end members 2...Intermediate member 4...Punch 5...Core 9...Die 1 Patent applicant Hitachi Powder Metallurgy Co., Ltd.

Claims (1)

[Scope of Claims] 1. Both end members are made of a wear-resistant sintered alloy made of either iron or copper, and the intermediate member has a higher ductility than the sintered alloy. A valve guide for an internal combustion engine having a composite structure, which is made of a metal material that corresponds to at least one of a member with a large diameter, a member with good thermal conductivity, and a member with a poor composition, wherein the axial length of the intermediate member is A valve guide for an internal combustion engine, which occupies 30 to 60% of the total length of the valve guide, and wherein both end members and an intermediate member are interlocked with each other in stepped cross sections and are tightly fitted together. 2. Both end members are made of a wear-resistant sintered alloy made of either iron or copper, and the intermediate member is a member with greater ductility than the sintered alloy, and thermal conductivity. In the method for manufacturing a valve guide for an internal combustion engine having a composite structure, which is made of a metal material that meets at least one of the following: a member with good properties and a member with a poor composition, the intermediate member has its inner diameter or outer diameter removed in steps. Both end members have a tapered joint outer diameter or inner diameter, and their axial length is set to be shorter than the step length of the intermediate member. With both end members fitted, they are inserted into a sizing mold and punched. By pressing downward, the thin end face of the intermediate member is plastically deformed to fill the gap between both end members and the intermediate member, and the member is pushed down in the radial direction, reducing the cross-sectional area, thereby making it possible to fit the two members together. A method of manufacturing a valve guide for an internal combustion engine, characterized in that the parts are tightly interlocked, compressed in the axial and radial directions, and stretched in the axial direction.