JPH08144841A - Aluminum cylinder block - Google Patents

Abstract

PURPOSE: To improve joining force between an insert casted liner made of cast iron and a cylinder block body and thermal conductivity. CONSTITUTION: An aluminum cylinder block is composed of a cylinder block body 1 formed castly of aluminum system alloy and a cylindrical liner 2 which is unitedly formed on the cylinder bore face of the cylinder block body 1 by insert casting and has through holes 20 piercing in the direction of thickness on a side peripheral face, and a part of the cylinder block body 1 is filled up in the through hole 20. The slipping down of the liner 2 can be prevented by anchoring effect caused by a filled up part in the through hole 20. In addition to that, since the filled up part is larger in thermal conductivity than the liner 2, the heat conductivity of the cylinder block is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum cylinder block made of an aluminum alloy having excellent wear resistance and heat conduction characteristics.

[0002]

2. Description of the Related Art In a cylinder block of an automobile engine, material replacement from cast iron material to aluminum alloy material is being promoted for the purpose of weight reduction. However, with aluminum alloys, wear due to sliding of the piston is large, so various measures have been taken to ensure wear resistance of the cylinder bore surface.

For example, Japanese Laid-Open Patent Publication No. 6-505197 discloses an aluminum cylinder block in which a cast iron liner is formed on the cylinder bore surface by cast molding.
It is also practiced to press-fit a cast iron liner into the cylinder block body. Also, without using a cast iron liner, a linerless method can be used to ensure wear resistance by coating the cylinder bore surface of an aluminum cylinder block with a hypereutectic Al-Si alloy or forming a plating layer. It is being appreciated.

[0004]

However, in the aluminum cylinder block in which the cast iron liner is arranged on the cylinder bore surface, the linerless method is used because the linerless method has a low thermal conductivity and a low wall wall cooling ability. There is a problem that the combustion efficiency is lower than that of, and the engine output and knock resistance are low.

Further, in an aluminum cylinder block in which a cast iron liner is arranged on the cylinder bore surface, the thermal expansion coefficients of the cylinder block body and the liner are different, so that thermal history causes separation at the interface between the two and the liner due to the frictional force of the piston. Has a problem of falling out of the cylinder block body. Therefore, it was attempted to improve the bondability with the cylinder block by casting a liner with a convex portion on the outer peripheral surface, but since the weight of the convex portion is added to the weight of the liner body, it is possible to reduce the weight. It was insufficient.

On the other hand, according to the linerless method, an aluminum cylinder block which is extremely lightweight and has a high thermal conductivity can be manufactured, but there is a problem that the manufacturing cost becomes high. The present invention has been made in view of such circumstances, and its main purpose is to improve the bonding force between a liner made of cast iron such as cast iron and the cylinder block body, and to increase the thermal conductivity. .

Another object of the present invention is to realize excellent wear resistance in the above aluminum cylinder block by using a more inexpensive material.

[0008]

An aluminum cylinder block according to a first aspect of the present invention is a cylinder block body made of an aluminum-based alloy and formed by casting, and a side formed integrally with the cylinder bore surface of the cylinder block body by cast-in-die casting. It is characterized by comprising a cylindrical liner having a through hole penetrating in the thickness direction on its peripheral surface, and the through hole is filled with a part of the cylinder block main body.

The aluminum cylinder block of the second invention is the same as the aluminum cylinder block of the first invention.
The cylinder block body is made of a hypoeutectic aluminum-based alloy that contains Si as a eutectic component, and the filling part filling the through holes of the liner contains more primary Si than other parts. Characterize.

[0010]

In the aluminum cylinder block of the first aspect of the present invention, the liner has a through hole penetrating the side peripheral surface in the thickness direction, and the through hole is partially filled with the cylinder block body. Therefore, an anchor effect is obtained by a part of the cylinder block body filling the through hole, and the liner is prevented from falling off. Further, since the metal of the through hole is replaced with the aluminum alloy in the liner, the liner becomes lighter accordingly.

Further, since a part of the cylinder block body made of an aluminum alloy having a large heat conductivity is exposed from the through hole on the cylinder bore surface constituted by the inner peripheral surface of the liner, the heat conduction characteristic is improved. To do. By the way, in the aluminum cylinder block of the first aspect of the invention, a part of the cylinder block body is exposed from the through hole to form a part of the cylinder bore surface. Therefore, the material of the cylinder block body is to ensure wear resistance. It is considered that a hypereutectic aluminum-based alloy that positively precipitates primary crystal Si is optimal.

However, in the second invention, in the aluminum cylinder block of the first invention, the cylinder block body is made of Si.
It is formed from an aluminum-based alloy having a hypoeutectic composition that contains as a eutectic component. Even when an aluminum-based alloy having a hypoeutectic composition, which is considered to be insufficient in wear resistance under normal conditions, is used, the present invention can obtain wear resistance almost equal to that of an aluminum-based alloy having a hypereutectic composition.

That is, when a cylinder block body having a liner is cast from a molten aluminum-based alloy of this hypoeutectic composition by casting, the diameter of the through hole is adjusted so that the molten metal surrounds the liner having a large flow path. It can be configured such that the liner is first filled and then the molten metal pressure is increased after the filling, and then the through hole of the liner is filled. In this case, the primary phase of the solid phase that crystallizes in the initial stage is mainly composed of primary crystal Al, and the amount of Al in the residual liquid phase is relatively reduced to form a eutectic composition. If pressure is applied at that time to fill the through holes of the liner, the primary crystal Al cannot enter the through holes because it forms a dendritic network, and only the residual liquid phase remains in the through holes. Is filled. Since this residual liquid phase has a eutectic composition, a large amount of primary crystal Si is distributed in the filling portion of the through hole, and wear resistance is improved.

[0014]

The present invention will be described below in detail with reference to examples. (Embodiment 1) FIG. 1 is a sectional view of an aluminum cylinder block of this embodiment. This aluminum cylinder block is composed of a cylinder block body 1 made of an aluminum-based alloy and a cast iron liner 2 arranged on the cylinder bore surface of the cylinder block body 1. The liner 2 is cast around the cylinder block body 1 during casting. Are integrated.

As shown in the perspective view of FIG. 2, the liner 2 has a cylindrical shape, and a plurality of through holes 20 penetrating in the thickness direction are formed on its side peripheral surface. Then, as shown in an enlarged manner in FIG. 3, the through hole 20 is filled with a part of the cylinder block main body 1, and the surface of the filling portion 10 is exposed at the inner peripheral surface of the liner 2 and a part of the cylinder bore surface is exposed. I am configuring.

According to the aluminum cylinder block of the present embodiment, since the filling portion 10 is filled in the through hole 20 of the liner 2, the weight of the liner 2 is reduced by the amount of the through hole 20 and is lighter. Even if the difference in coefficient of thermal expansion between the cylinder block body 1 and the liner 2 is large, the liner 2 is prevented from falling off by the anchoring action of the filling portion 10.

Since the cylinder block body 1 is made of an aluminum alloy, the filling portion 10 has a higher thermal conductivity than the liner 2. Therefore, the heat of the cylinder bore surface is smoothly radiated to the outside from the filling portion 10 via the cylinder block body 1 regardless of the material of the liner 2, so that the combustion efficiency is improved and the engine output and the knock resistance are improved. be able to.

The material of the cylinder block body 1 of the aluminum cylinder block of the present invention is not particularly limited as long as it is an aluminum type alloy, and Al-Si type alloy, Al
-Cu-Mg-Si type alloy, Al-Mg-Si type alloy, etc. can be used. In order to secure the wear resistance of the filling portion 10, it is preferable to use an alloy having a hypereutectic composition containing Si as a eutectic component.

This aluminum cylinder block can be easily manufactured by arranging a preformed liner 2 in a mold, casting a molten aluminum alloy into the liner 2, and surrounding the liner 2. (Example 2) In this example, a hypoeutectic AC4C alloy (Al-7% Si-0.3%) was used as an aluminum alloy.
Mg) was selected, and the formation depth of the filling portion 10 formed in the through hole 20 was examined by setting the diameter of the through hole 20 of the liner 2 to various values. The liner 2 has a thickness of 5 mm, and the filling part 1
0 is the maximum formation depth of 5 mm.

First, the liner 2 is placed in the mold, and AC4C
The molten alloy is poured into the outer cavity of the liner 2. Then, while the solid fraction was 0.8 or less, the molten metal was pressurized at a pressure of 80 MPa to form the filling portion 10. FIG. 4 shows the formation depth of the filling portion 10 of each obtained aluminum cylinder block.
Shown in It can be seen from FIG. 4 that when the diameter of the through hole 20 is 0.5 mm or less, the filling portion 10 is not sufficiently formed and the through hole 20 is not completely filled. Therefore, under the above molding conditions and when the thickness of the liner 2 is 5 mm, the through hole 2
The diameter of 0 is preferably 0.5 mm or more.

Next, with respect to each of the plurality of aluminum cylinder blocks obtained above, the amount of Si in the filling portion 10 was measured by a high frequency plasma emission analyzer. Results are shown in FIG. From FIG. 5, when the diameter of the through hole 20 is 10 mm or more, the Si content of the filling portion 10 is almost equal to the initial alloy composition, but when it is less than 10 mm, the Si content is larger than the initial alloy composition. This is because when the diameter of the through hole 20 is less than 10 mm, the molten metal is first filled around the liner 2 having a large flow path, and after the filling, the molten metal pressure increases and then the liner 2
It shows that the through hole 20 of FIG.

In this case, the solid phase that initially crystallizes is the primary crystal Al.
Is the main component, and this primary crystal Al constitutes a dendritic network, and in the residual liquid phase, the amount of Al is relatively reduced to form a eutectic composition. At that point, pressurize and the diameter is 10m
If the through holes 20 of less than m are filled, the primary crystal Al will pass through the through holes 2
Therefore, the through hole 20 is filled with only the residual liquid phase having a large amount of Si.

On the other hand, when the diameter of the through hole 20 is 10 mm or more, even the crystallized primary crystal Al flows into the through hole 20, so that the filling portion 10 has substantially the same Si content as that of the initial alloy. Therefore, if the diameter of the through hole 20 is less than 10 mm, the alloy component of the filling portion 10 is about Al-12% Si, and the amount of Si increases up to the eutectic composition. This is the through hole 2
When it is filled with 0, it is rapidly cooled, and a large amount of primary crystal Si is distributed on the surface of the filled portion 10 of the through hole 20 to improve wear resistance. Since this phenomenon commonly occurs in Al-2 to 10% Si alloys, even when an aluminum-based alloy having a hypoeutectic composition such as an ADC10 alloy or an AC2C alloy is used, the Si of the filling portion 20 is similarly changed.
The amount can be increased, and primary crystal Si can be crystallized.

6 and 7 show micrographs (50 times) of the filling portion 10 of the cylinder block body 1 and the other portion of the structure when the diameter of the through hole 20 is 6 mm. Although a large amount of primary crystal Si is crystallized in the filling portion 10 in FIG. 6, only a small amount of primary crystal Si is observed in FIG. 7, which confirms that the above-described action occurs. That is, in the aluminum cylinder block of the present embodiment, despite the use of an inexpensive hypoeutectic AC4C alloy or the like as the material of the cylinder block body, the filling portion 10 is crystallized in a large amount of primary crystal Si and is wear resistant. Is excellent.

Although a single cylinder block has been described in the above embodiment, it is preferable to use a connecting liner as shown in FIG. 8 in practice. Even with such a connection liner, it is apparent that the same effect as the above-described embodiment can be obtained by appropriately providing the through hole 20.

[0026]

According to the aluminum cylinder block of the first aspect of the present invention, the weight of the liner is reduced by the amount of the through hole, and the weight can be further reduced. In addition, since the filled portion filling the inside of the through hole has a high thermal conductivity, the thermal conductivity characteristics are improved. The anchor effect of the filling portion reliably prevents the liner from falling off.

Further, according to the aluminum cylinder block of the second invention, since a large amount of primary crystal Si is present in the filling portion using an inexpensive aluminum alloy having a hypoeutectic composition, in addition to the above effects, the cylinder bore surface is inexpensive. Has excellent wear resistance.

[Brief description of drawings]

FIG. 1 is a sectional view of an aluminum cylinder block according to an embodiment of the present invention.

FIG. 2 is a perspective view of a liner used in an aluminum cylinder block according to an embodiment of the present invention.

FIG. 3 is an enlarged sectional view of an essential part of the aluminum cylinder block according to the embodiment of the present invention.

FIG. 4 is a graph showing a relationship between a diameter of a through hole and a depth of a filling portion filled with the through hole.

FIG. 5 is a graph showing a relationship between a diameter of a through hole and an amount of Si in a filling portion filled with the through hole.

FIG. 6 is a micrograph showing a crystal structure of a filling portion filled with a through hole of an aluminum cylinder block according to an embodiment of the present invention.

FIG. 7 is a micrograph showing a crystal structure of a cylinder block body of an aluminum cylinder block according to an example of the present invention.

FIG. 8 is a perspective view of a connection liner showing another aspect of the liner shape.

[Explanation of symbols]

 1: Cylinder block body 2: Liner 10: Filling part 20: Through hole

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[Procedure amendment]

[Submission date] January 13, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

Claims (2)

[Claims] 1. A cylinder block main body made of aluminum alloy by casting, and a through hole penetrating in the thickness direction on the side peripheral surface integrally formed on the cylinder bore surface of the cylinder block main body by cast-in-die casting. An aluminum cylinder block, characterized by comprising a cylindrical liner having a through hole and a part of the cylinder block body being filled in the through hole. 2. The cylinder block body is made of a hypoeutectic aluminum-based alloy containing Si as a eutectic component,
The primary crystal Si is present in a larger amount in the filling portion filling the through hole of the liner than in other portions.
Aluminum cylinder block described.