JPH1113434A - Method for improving heat radiating performance of fitted body in internal combustion engine cylinder head and fitting part of fitted body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the durability of a fitted body by forming a brazing filler metal film diffused and dissolved with a cylinder head or a fitted body in one of the fitted body of the cylinder head and its holding hole at a highest temperature or lower reached by the fitted body during running of an engine and then fitting the fitted body to the cylinder head. SOLUTION: Holding holes 3 and 4 are provided in the upper and lower parts of an exhaust hole 2 in a cylinder head 1, and a valve guide 7 and a valve sheet 10 as fitted bodies are fitted into the holding holes 3 and 4. In this case, brazer covering films (a) and (b) are formed in one of contact surfaces between the fitted bodies 7 and 10 and the holding holes 3 and 4. Selected for this brazer is a material which becomes an alloy diffused and dissolved with the cylinder head 1 or the fitted body 7 at a highest temperature or lower reached by the fitted bodies 7 and 10 and having a melting point higher than the highest temperature. Then, the fitted bodies 7 and 10 are press fitted into the holding holes 3 and 4, the films (a) and (b) are melted following the running of an engine, and the films, the cylinder head 1 and the fitted bodies 7 and 10 are diffused and dissolved to be integrally connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the heat radiation of an object to be fitted, such as a valve guide or a valve seat, fitted to a key point of a cylinder head for an internal combustion engine,
The present invention relates to a fitting portion of a body to be fitted, which is used for performing this method.

[0002]

2. Description of the Related Art As is well known, an exhaust hole in a cylinder head of a general internal combustion engine is periodically opened and closed by a valve which is moved up and down by a rocker arm and a compression spring. Therefore, the shaft portion of the valve is slidably inserted into a cylindrical valve guide fitted and fixed to the upper surface of the inlet of the exhaust hole, and the valve face surface around the umbrella portion at the lower end as the valve moves up and down. However, it comes into contact with or separates from the valve seat fitted and fixed to the inlet of the exhaust hole.

The above-mentioned valve guide and valve seat are required to have high heat resistance, abrasion resistance, impact resistance, and the like. Therefore, a material different from a cylinder head which is usually made of cast iron or light metal, for example, heat-resistant steel And is firmly fitted and fixed in a holding hole provided at a key point of the cylinder head.

The above-mentioned valve guide and valve seat (hereinafter, these are collectively referred to as fitting bodies) are naturally finished to a high degree so as to be sufficiently close to the inner surfaces of the respective holding holes in the cylinder head. Although they are fitted with a high degree of fitting, the fact is that the fitted body and the holding hole are not completely integrated from the viewpoint of heat.

[0005] That is, even if the finishing accuracy of the contacting surface is improved, and no matter how mechanically a firm and complete fitting is performed, microscopic unevenness is not left on the contact surfaces of both. However, due to the gap formed by the unevenness, a heat transfer step is generated on the contact surface, and the heat of the fitted body is not completely transmitted to the cylinder head side.

If the object to be fitted and the cylinder head can be completely integrated from the viewpoint of heat and therefore metallurgy, the heat radiation of the object to be fitted becomes better,
As a result, it is clear that the durability of the fitted body is improved and the cooling effect of the entire cylinder head is also improved.

A concrete method for implementing such an idea for improving the heat radiation performance of a body to be fitted in a cylinder head of an internal combustion engine as simply and inexpensively as possible, and the fitting of the body to be fitted for use in this method. As a joint, the present applicant has already proposed one disclosed in Japanese Patent Application Laid-Open No. 8-144723.

In this conventional method, a coating of a brazing material which can be melted at a temperature not higher than the maximum temperature at which the object to be fitted reaches during operation of the internal combustion engine is applied to one of the object to be fitted and its holding hole in the cylinder head of the internal combustion engine. After being formed in advance, the fitting object is pressed into the holding hole in the cylinder head, and the film of the brazing material is melted with the operation of the internal combustion engine. It is characterized in that a gap formed by minute irregularities on the contact surface of the united body is closed.

The fitting portion of the fitting body of the conventional cylinder head of the internal combustion engine reaches one of the fitting body and the holding hole of the cylinder head of the internal combustion engine during the operation of the internal combustion engine. It is characterized in that a film of a brazing material that can be melted at a temperature lower than the maximum temperature is formed.

[0010]

However, in the above-mentioned conventional method and the structure of the fitting portion, each time the internal combustion engine is operated, the brazing material is melted, and the brazing material is melted due to vibration during operation of the internal combustion engine. Even if the brazing filler metal gradually flows out from between the cylinder head and the fitting body, even if it does not flow out, air bubbles are generated between the holding hole and the fitting body, heat transfer deteriorates, and heat dissipation performance May decrease.

If the brazing material is constantly melted during operation, loosening is likely to occur between the holding hole and the fitting.
The body to be fitted easily falls off from the holding hole.

According to the present invention, the brazing material is melted by reaching a required temperature during the first operation or heating of the internal combustion engine, and is prevented from melting even after reaching the same temperature as described above. It is an object of the present invention to provide a method for improving the heat radiation performance of a body to be fitted in a cylinder head for an internal combustion engine which has solved the above problems, and a fitting portion of the body to be fitted.

[0013]

According to the present invention, the above-mentioned problem is solved as follows. (1) In the method for improving the heat radiation performance of a body to be fitted in a cylinder head for an internal combustion engine, the maximum amount of the body to be fitted that reaches the body to be fitted and one of its holding holes in the cylinder head of the internal combustion engine during operation of the internal combustion engine. By diffusing and melting with the cylinder head or the fitting body at a temperature equal to or lower than a temperature, a coating of a brazing material having a property that the melting point becomes an alloy higher than the maximum temperature is formed in advance, and then the fitting body is set in the cylinder head. By press-fitting into the holding hole, and with the operation of the internal combustion engine, by melting the film of the brazing material, the brazing material is used to close the gaps due to minute irregularities on the contact surface between the holding hole and the fitting, and The brazing material is diffused and melted with the cylinder head and the fitting object to form an alloy having a melting point higher than the maximum temperature.

(2) The maximum temperature at which the fitted body reaches during operation of the internal combustion engine by diffusing and dissolving the cylinder head or the fitted body in one of the fitted body and the holding hole in the cylinder head of the internal combustion engine. After previously forming a brazing material film having the property of becoming a higher alloy,
The fitting object is pressed into the holding hole in the cylinder head, and then the film of the brazing material is heated and melted, so that the brazing material closes the gap due to minute unevenness on the contact surface between the holding hole and the fitting object. Then, the brazing material is diffused and melted in the cylinder head and the fitting object to form an alloy having a melting point higher than the maximum temperature.

(3) In the above item (1) or (2), the cylinder head is formed of an aluminum-based material, the body to be fitted is formed of an iron-based material, and the brazing material is formed of a material containing zinc and aluminum. It shall be.

(4) In any one of the above items (1) to (3), the surface of the body to be fitted before forming the brazing material film is plated with copper in advance.

(5) At the fitting portion of the body to be fitted in the cylinder head for the internal combustion engine, the body to be fitted reaches between the body to be fitted and the holding hole of the cylinder head of the internal combustion engine during operation of the internal combustion engine. Below the maximum temperature, and by diffusion and melting with the cylinder head or the fitting
A film of a brazing material having a property that the alloy has a melting point higher than the maximum temperature is formed.

(6) In the above item (5), the cylinder head is made of an aluminum-based material, the body to be fitted is made of an iron-based material, and the brazing material is made of a material containing zinc and aluminum.

(7) In the above item (5) or (6), a copper plating layer is formed between the brazing material film and the surface of the fitting.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG.
A vertical upper holding hole (3) is formed directly above the inlet of the exhaust hole (2) in (1), and a lower holding hole (4) is formed at the edge of the inlet of the exhaust hole (2). I have.

The upper holding hole (3) has a shaft portion of the valve (5).
A cylindrical valve guide (7) into which (6) is slidably inserted is fitted and fixed.

A valve seat (10) with which the face surface (9) of the umbrella (8) at the lower end of the valve (5) abuts the lower holding hole (4).
Are fitted and fixed.

One or both of the contact surfaces between the valve guide (7) and the upper holding hole (3) and between the valve seat (10) and the lower holding hole (4) are provided with each holding hole (3) (4). Prior to fitting into ()), the coatings (a) and (b) of the brazing material are formed.

[0024] The brazing material is the maximum temperature reached by the valve guide (7) or the valve seat (10) during operation of the internal combustion engine.
(Usually 150-450 ° C) or less, it diffuses and dissolves in the cylinder head (1) and the valve guide (7) or valve seat (10), which is the object to be fitted, to form an alloy whose melting point is higher than the above maximum temperature. Choose what you have.

For example, when the cylinder head (1) is made of an aluminum-based material and the body to be fitted is made of an iron-based material, a Zn-AI-based brazing material having a melting point of about 382 ° C. (for example, Zn 94 ~ 96%, AI 4 ~ 6%, other elements
It is preferable to use JIS standard AH-Z95A) including 3 or less.

At this time, it is preferable that the surface of the fitting object is plated with copper as a base of the brazing material.

The coatings (a) and (b) of the brazing material are plated, dipped,
It is formed by thermal spraying, powder coating, or the like, but the amount of the brazing material only needs to be an amount sufficient to close the gap due to the unevenness of the contact surface during melting. In other words, the unevenness of the surface at the time of fitting of each member on the contact surface is, for example, 1.
Assuming that the thickness is 5μ, 3μ is sufficient for the thickness of the brazing material.

The valve guide (7) and the valve seat (10) on which the coatings (a) and (b) of the brazing material are formed are
The internal combustion engine is operated by press-fitting into the respective holding holes (3) and (4) as in the conventional case.

Then, a holding hole in the cylinder head (1) where the valve guide (7) and the valve seat (10) abut.
(3) The inner surface of (4) reaches the operating temperature of the internal combustion engine in a short time, and the coatings (a) and (b) of the brazing material having a lower melting point are melted to form irregularities on the mutual contact surface. The molten brazing material diffuses into the cylinder head (1) and the body to be fitted together with the cylinder head (1) and the object to be fitted together, and the melting point of the molten brazing material during operation of the internal combustion engine is reduced. Higher than or near the maximum temperature.

In this way, the brazing material diffuses and dissolves,
After alloying, it does not melt again during the subsequent operation of the internal combustion engine. In addition, the brazing material melts and the holding holes
(3) The cylinder head (1), the valve guide (7), and the valve seat (10) are thermally integrated completely by flowing into the uneven portion on the inner surface of (4) and completely closing the gap. The heat of the valve guide (7) and the valve seat (10) is appropriately radiated through the cylinder head (1), thereby improving the durability thereof and the cooling effect of the cylinder head (1) as a whole. Also improve.

As shown in FIG. 2, in order to confirm that the brazing material may be melted and diffused and melted with the cylinder head and the like to form an alloy having a melting point higher than the melting point of the first brazing material.
Copper, commonly used as cylinder head (1)
% Aluminum alloy cylinder head material (11),
The Zn-AI brazing material (14) (Zn94) is interposed between the fitting body (13) made of an iron-based material having a copper plating layer (12) on the surface.
9696%, AI 4-6%, other elements 0.3 or less) and press them together. In this state, the whole is heated to about 400 ° C., then cooled naturally, and the joint is qualitatively determined by X-ray microanalyzer. analyzed.

The result is as shown in FIG. Table 1 shows the results obtained by superposing the content curves of the respective components shown in FIG. 3 and examining the compositions and melting temperatures of three arbitrary points (A), (B), and (C) at the joint.

[0033]

[Table 1]

As is clear from FIG. 3 and Table 1, at the joint portion, an alloy layer composed of AI-Zn-Cu having different component ratios from the cylinder head material (11) side to the fitting object (13) side. Although formed, this alloy layer has the property that the melting point is higher than the melting point of the original brazing material (13) in any part.

Therefore, even if this alloy layer is again exposed to the maximum temperature of 400 ° C. to 450 ° C. during operation of the internal combustion engine, it does not remelt. The alloy layer composed of AI-Zn-Cu is composed of the cylinder head material (11) and the fitting object (13).
Has a strong affinity with iron-based materials, and has a high mutual binding force with them.

In this experimental example, it is recognized that the brazing material (14) is diffused and dissolved in both the cylinder head material (11) and the fitting object (13), but the melting point is finally high. If an alloy can be obtained, only one of them may be diffused and melted.

In order to confirm the effect of improving the heat radiation of the present invention, iron and an aluminum alloy whose contact surfaces have irregularities of about 1.5 μ are firmly butted, one end of which is heated by a burner and the other end is heated. As a result, it was confirmed that when the brazing material film was provided as in the present invention, the heat transfer was improved by about 70% as compared with the case where the brazing material film was not provided.

In the above embodiment, the operating temperature of the internal combustion engine is used to melt the brazing material. However, before the cylinder head is assembled to the engine, the brazing material is melted by an appropriate heating means in advance. Is also good. By doing so,
It is also possible to use a brazing material whose melting temperature is slightly higher than the maximum temperature during operation of the internal combustion engine.

[0039]

According to the present invention, the following effects can be obtained. (a) According to the first and fifth aspects of the present invention, the cylinder head and the body to be fitted to the cylinder head are almost integral with each other when viewed thermally, so that the cooling effect of the entire cylinder head is improved, and The durability of the fitting body is also improved.

Furthermore, once the brazing material is raised to the temperature at the time of operation of the internal combustion engine, it is diffused and melted with the cylinder head or the fitting, and becomes an alloy whose melting point is higher than the maximum temperature at the time of operation of the internal combustion engine. Thereafter, when the internal combustion engine is operated, the brazing material does not melt again.

Therefore, every time the internal combustion engine is operated, the brazing material is melted, and the molten brazing material gradually flows out of the cylinder head and the fitting body due to vibration during operation of the internal combustion engine, or is held. There is no danger that air bubbles are generated between the hole and the fitted body, heat transfer is deteriorated, and heat radiation performance is reduced.

Further, the melting of the brazing material can prevent loosening between the holding hole and the body to be fitted, and prevent the body to be fitted from falling out of the holding hole.

(B) According to the second aspect of the present invention, a brazing filler metal having a melting temperature slightly higher than the maximum temperature during operation of the internal combustion engine can be used.

(C) According to the third and sixth aspects of the present invention, it is effective when the cylinder head is formed of an aluminum-based material and the body to be fitted is formed of an iron-based material.

(D) According to the fourth and seventh aspects of the present invention, the copper plated on the surface of the body to be fitted is diffused and dissolved in the brazing material, and the alloying of the brazing material is promoted.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a cylinder head of an internal combustion engine embodying the present invention.

FIG. 2 is an enlarged sectional view of a joint using a brazing material.

FIG. 3 is a view showing the results of qualitative analysis of a joint after melting of a brazing material using an X-ray microanalyzer.

[Explanation of symbols]

 (1) Cylinder head (2) Exhaust hole (3) Upper holding hole (4) Lower holding hole (5) Valve (6) Shaft (7) Valve guide (8) Head (9) Face (10) Valve Sheet (11) Cylinder head material (12) Copper plating layer (13) Material to be fitted (14) Brazing material (a) (b) Coating of brazing material

Claims (7)

[Claims] The present invention relates to a cylinder head of an internal combustion engine, which diffuses and dissolves in one of a fitting body and a holding hole of the cylinder head or the fitting body at a temperature not higher than a maximum temperature at which the fitting body reaches during operation of the internal combustion engine. After forming a coating of a brazing material having a property such that the melting point of the alloy becomes higher than the maximum temperature, the fitting object is pressed into a holding hole in a cylinder head, and the internal combustion engine is operated. By melting the film of the brazing material, the brazing material closes the gap due to the minute irregularities on the contact surface between the holding hole and the fitting object, and diffuses and dissolves the brazing material with the cylinder head and the fitting object. Wherein the alloy has a melting point higher than the maximum temperature. 2. The method according to claim 1, further comprising the step of diffusing and dissolving the cylinder head or the fitting body into any one of the fitting body and the holding hole in the cylinder head of the internal combustion engine so that the maximum temperature reached by the fitting body during operation of the internal combustion engine is reduced. After previously forming a film of a brazing material having the property of being a high alloy, the fitting object is pressed into a holding hole in a cylinder head, and then, the film of the brazing material is heated and melted.
An alloy having a brazing material, which closes a gap formed by minute irregularities on the contact surface between the holding hole and the fitting object, and diffuses and dissolves the brazing material with the cylinder head and the fitting object, and has a melting point higher than the maximum temperature. A method for improving heat radiation performance of a body to be fitted in a cylinder head for an internal combustion engine. 3. The method according to claim 1, wherein the cylinder head is formed of an aluminum-based material, the body to be fitted is formed of an iron-based material, and the brazing material is formed of a material containing zinc and aluminum. 3. A method for improving the heat radiation performance of an object to be fitted in a cylinder head for an internal combustion engine according to item 2. 4. The cylinder head for an internal combustion engine according to claim 1, wherein the surface of the body to be fitted before forming the brazing material film is plated with copper in advance. How to improve the heat dissipation performance of the fitting. 5. A temperature lower than the maximum temperature at which the fitted body reaches during operation of the internal combustion engine between the fitted body and the holding hole in the cylinder head of the internal combustion engine, and diffusion and melting with the cylinder head or the fitted body. A fitting portion of a fitting body in a cylinder head for an internal combustion engine, wherein a coating of a brazing material having a property of forming an alloy having a melting point higher than the maximum temperature is formed. 6. The cylinder head according to claim 5, wherein the cylinder head is formed of an aluminum-based material, the body to be fitted is formed of an iron-based material, and the brazing material is formed of a material containing zinc and aluminum. A fitting portion of a body to be fitted in a cylinder head for an internal combustion engine. 7. The fitting of an object to be fitted in a cylinder head for an internal combustion engine according to claim 5, wherein a copper plating layer is formed between the coating of the brazing material and the surface of the object to be fitted. Joint part.