JPH0687647U - Engine cylinder liner - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an engine cylinder liner capable of improving the cooling performance of the engine combustion chamber, reducing the weight, reducing the piston hammering sound, etc. while sufficiently maintaining the wear resistance performance for the piston ring. . [Structure] A cylinder liner 3 used for an engine made of an aluminum alloy having a composition with a higher silicon density toward the inner peripheral side by centrifugal casting using a high silicon aluminum alloy as a material.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a cylinder liner used for an aluminum alloy engine.

[0002]

[Prior art]

 Generally, in a dry liner type aluminum alloy engine, as shown in FIG. 2, a cylinder block c is formed by integrally casting a cylinder liner b around the inner circumference of a cylinder block body a. While the cylinder block body a and the piston (not shown) are made of aluminum alloy, the cylinder liner b is generally made of cast iron in consideration of the wear strength with the piston ring mounted on the piston.

Various proposals have heretofore been made regarding cast iron cylinder liners. For example, in JP-A-60-36755, an outer layer is formed of a spheroidal graphite cast iron material containing a specific component, A composite cylinder liner is disclosed in which the inner layer is formed of a special cast iron material made of a specific component and the two are welded and bonded to each other to maintain wear resistance and seizure resistance and to increase the strength thereof.

Further, in JP-A-60-36757, an outer layer is a pseudo-spheroidal graphite cast iron material of a specific component, an inner layer is a special cast iron material of a specific component, and an intermediate layer is a special cast iron material of a specific component for joining. A composite cylinder liner is disclosed, which is formed of a material to maintain wear resistance and seizure resistance and to have high strength.

Further, in Japanese Patent Laid-Open No. 62-267548, an inner layer is formed by spraying and diffusing alloy powder on the inner peripheral surface of the outer layer formed by centrifugal casting, and the inner and outer surfaces are machined and finished. As a result, a two-layer cylinder liner with high strength and light weight is disclosed.

[0006]

[Problems to be solved by the device]

 By the way, in the conventional cylinder block c shown in FIG. 2, since the cylinder block main body a made of aluminum alloy and the cast iron cylinder liner b having a smaller thermal conductivity than the piston are used, the cooling efficiency thereof is improved. Unfortunately, the cooling of the combustion chamber including the piston was not always perfect. Further, since the cylinder liner b is made of cast iron, which has a larger specific gravity than aluminum alloy, it has been an obstacle to reducing the weight of the engine.

Further, since the cast iron and the aluminum alloy have large thermal expansion coefficients, a gap is likely to be formed between the cylinder liner b and the cylinder block body a when the engine is at a high temperature. Therefore, there is a possibility that the cooling performance in the combustion chamber may be deteriorated, the cylinder liner b may rotate with respect to the cylinder block body a, or the cylinder liner b may slip out.

Further, due to the difference in the coefficient of thermal expansion, there is a problem that the clearance between the cylinder liner b and the piston increases at the time of high temperature of the engine and the piston hammering sound increases.

Since the cylinder liners described in each of the above publications are made of cast iron or steel, the same problem occurs when used in an aluminum alloy engine.

Therefore, the present invention provides a cylinder liner for an engine, which can improve the cooling performance of the engine combustion chamber, reduce the weight, reduce the piston hammering sound, etc. while sufficiently maintaining the wear resistance performance for the piston ring. The purpose is to

[0011]

[Means for Solving the Problems]

 In order to achieve this object, the present invention is a cylinder liner used in an engine made of an aluminum alloy, which is formed by centrifugal casting using a high silicon aluminum alloy as a material having a higher silicon density toward the inner peripheral side. I am trying.

[0012]

[Action]

 The engine cylinder liner according to the present invention adopting such a means is made of an aluminum alloy whose specific gravity is about 1/3 smaller than that of conventional cast iron, so that the engine is lightened.

Further, the material of this cylinder liner is an aluminum alloy having a large thermal conductivity, and the cooling efficiency of the cylinder liner itself is good. Moreover, since the difference in the coefficient of thermal expansion from the cylinder block body is small, a gap is unlikely to occur between the cylinder liner and the cylinder block body even when the engine temperature is high, and even if it occurs, the amount is extremely small. Therefore, the heat conduction from the cylinder liner to the cylinder block body is favorably performed, and the cooling performance of the engine combustion chamber is improved.

Further, in this cylinder liner, since the difference in the coefficient of thermal expansion from the piston is also small, the clearance between the cylinder liner and the piston does not increase significantly when the engine temperature is high, and the piston hammering noise is reduced compared to the conventional case. .

Here, since the cylinder liner according to the present invention has a composition in which the silicon density is higher toward the inner peripheral side, the wear resistance performance for the piston ring mounted on the piston is sufficiently maintained.

[0016]

【Example】

 Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. In FIG. 1 (a) showing a cylinder block 1 of an aluminum alloy engine, reference numeral 2 indicates a cylinder block body 2 formed by casting an aluminum alloy, and a cylinder liner 3 according to one embodiment is cast around the inner periphery of the cylinder block body 2. .

Here, the cylinder liner 3 is made of, for example, a high silicon-based aluminum alloy such as A390, and is formed by centrifugal casting so that silicon having a specific gravity smaller than that of aluminum is distributed more on the inner peripheral side. As shown in FIG. 1 (b), the silicon density is higher toward the inner circumference side and gradually lowers toward the outer circumference side.

A piston (not shown) made of an aluminum alloy is fitted into the cylinder liner 3 of the present embodiment having the above-described configuration. The aluminum alloy engine thus assembled has a cylinder liner 3 The material is a high-silicon aluminum alloy, and its specific gravity is about 1/3 that of conventional cast iron, so it is lighter in weight.

Further, in the aluminum alloy engine using the cylinder liner 3 of the present embodiment, the piston ring mounted on the piston slides reciprocally on the inner peripheral surface of the cylinder liner 3 during its operation. Since the composition of 3 has a higher silicon density toward the inner peripheral side, the wear resistance performance against sliding of the piston ring is sufficiently maintained.

Here, the cylinder liner 3 of the present embodiment is a dry liner type, but since the material is an aluminum alloy and has a high thermal conductivity, the cylinder liner 3 itself has good cooling efficiency. However, because the difference in the coefficient of thermal expansion from the cylinder block body 2 made of aluminum alloy is small, it is difficult for a gap to form between the cylinder block body 2 and the cylinder block body 2 even when the engine temperature is high. Is extremely small. Therefore, there is no possibility that the cylinder liner 3 will rotate with respect to the cylinder block body 2 or will slip out of the cylinder block body 2 during engine operation. In particular, since no large gap is generated between the cylinder liner 3 and the cylinder block body 2, heat conduction from the cylinder liner 3 to the cylinder block body 2 side is performed well, and the engine combustion chamber is cooled. Performance is improved.

Further, the cylinder liner 3 of the present embodiment is made of a high silicon-based aluminum alloy and has a small difference in coefficient of thermal expansion from the piston made of an aluminum alloy. The clearance between them does not increase significantly. Therefore, the piston striking sound is reduced as compared with the conventional case.

The cylinder liner 3 of the present embodiment has a composition in which the silicon density gradually decreases from the inner peripheral side toward the outer peripheral side, and the silicon density continuously changes in the thickness direction. Even if internal strain occurs due to the temperature difference between the inner and outer circumferences, it will not be inadvertently deformed or damaged.

[0023]

[Effect of device]

 As described above, the cylinder liner of the present invention is made of an aluminum alloy whose specific gravity is about 1/3 smaller than that of conventional cast iron, so that the weight of the engine can be reduced.

In addition, the cylinder liner of the present invention is made of an aluminum alloy having a high thermal conductivity, has a good cooling efficiency itself, and has a small difference in coefficient of thermal expansion from the cylinder block body. Even at times, it is difficult for a gap to form between the cylinder liner and the main body of the cylinder block, and even if it does occur, the amount is extremely small. Therefore, the heat conduction from the cylinder liner to the cylinder block body is favorably performed, and the cooling performance of the engine combustion chamber can be improved.

Furthermore, the cylinder liner of the present invention has a small difference in coefficient of thermal expansion from the piston, so that the clearance between the cylinder liner and the piston does not increase significantly when the engine temperature is high, and the piston striking sound is also higher than that of the prior art. Can be reduced.

Since the cylinder liner of the present invention has a composition in which the silicon density is higher toward the inner peripheral side, it is possible to sufficiently maintain the wear resistance performance for the piston ring mounted on the piston.

[Brief description of drawings]

FIG. 1 shows a cylinder block to which an embodiment of the present invention is applied. (A) is a longitudinal sectional view thereof, (b) is B of (a).
It is a partial expanded sectional view which follows the -B line.

FIG. 2 is a vertical sectional view of a conventional cylinder block.

[Explanation of symbols]

 1 Cylinder block 2 Cylinder block body 3 Cylinder liner

Claims (1)

[Scope of utility model registration request] 1. A cylinder liner used for an engine made of an aluminum alloy, characterized in that a composition having a higher silicon density toward the inner peripheral side is formed by centrifugal casting using a high silicon aluminum alloy as a raw material. Liner.