JP2001241359A - Cylinder structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder structure of an internal combustion engine capable of generating high output without decreasing durability. SOLUTION: In the cylinder structure 1 of the internal combustion engine, a cylinder block 2 forming a bore and a cylinder head 3 closing the end part thereof to contain combustion gas are formed by so-called lighter weight materials. The cylinder head 3 abuts and is tightened on a tightening surface 11 formed orthogonally to a bore axis in the end part of the cylinder block 2. A cylindrical sleeve 4 made of a heat-resistant material is press-fitted into the cylinder block 2. The end part of the sleeve 4 forms a diameter expanding part 15 press-fitted and positioned in the bore-axial direction. A sleeve end surface 16 orthogonal to the bore axis in a stepped manner from the tightening surface 11 is formed in the end part of the sleeve 4 and arranged close to the opposed surfaces of the cylinder head 3. In addition, a fitting peripheral surface 19 fitted in tight contact with the cylinder head 3 is formed on a certain radius from the center of the bore between the surface 16 and the tightening surface 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder structure of an internal combustion engine made of a so-called lightweight material mainly composed of aluminum, and more particularly, to a cylinder structure of an internal combustion engine capable of achieving high output without reducing durability. About.

[0002]

2. Description of the Related Art A conventional internal combustion engine 101 for lightweight and high output.
As shown in FIG. 5 showing a cross section of the main part, a cylinder block 102 made of a lightweight material mainly made of aluminum and a cylinder head 103 are fastened, and a gasket 104 made of a soft material mainly made of copper or the like is provided on the fastening surface. The interposed structure ensures the pressure resistance and achieves a high output by a high compression ratio.

[0003]

However, since the gasket 104 is exposed to the high-temperature combustion gas in the upper part of the cylinder, rapid deterioration of the material is unavoidable, so that the pressure resistance is reduced due to embrittlement. That is, if a high compression ratio is aimed at, the durability deteriorates, and the compression ratio and the durability have an inversely proportional relationship and are incompatible. Therefore, the compression ratio has to be suppressed according to required durability conditions.

An object of the present invention is to provide a cylinder structure of an internal combustion engine that can achieve high output with the same cylinder capacity without reducing durability.

[0005]

In order to solve the above-mentioned problems, a cylinder block having a bore and a cylinder head which closes an end of the cylinder block and seals a combustion gas are formed of a so-called lightweight material. In a cylinder structure of an internal combustion engine in which a cylinder head is abutted and fastened to a fastening surface formed perpendicular to a bore shaft, a cylindrical sleeve made of a heat-resistant material is press-fitted into the cylinder block, and the end of the sleeve is bored with a bore shaft. The sleeve has an enlarged diameter portion for press-fitting and positioning in the direction, and has a step formed from the fastening surface at its end to form a sleeve end surface orthogonal to the bore axis. A fitting peripheral surface is formed between the end surface and the fastening surface so as to closely fit with the cylinder head at a constant radius from the center of the bore.

In the cylinder structure of the internal combustion engine having the above-described structure, the sleeve is positioned in the cylinder axis direction by the enlarged diameter portion, and this sleeve secures the wear resistance of the piston sliding surface to protect the cylinder block. A step-shaped labyrinth from the sleeve end face to the fastening face is formed between the cylinder head and the cylinder head. This labyrinth is formed by a long path consisting of a gap between the sleeve end faces that enables high-precision dimensional control, a fitting peripheral surface that produces a large flow resistance due to close fitting, and a fastening surface that is strongly closely contacted by a large fastening force. Thus, the passage of high-pressure combustion gas in the bore can be effectively prevented.

In the sleeve, a counterbore bottom surface perpendicular to the bore axis and a counterbore peripheral surface having a constant radius from the bore center are formed in a counterbore shape, leaving an outer peripheral side of the end surface of the sleeve, and the counterbore bottom surface is formed in a counterbore surface with the cylinder head. A long path consisting of a gap between the counterbore bottom surface that is close to and can be closely fitted to the cylinder head on the counterbore peripheral surface to enable high-precision dimensional control, and a counterbore peripheral surface that generates a large flow resistance due to the close fitting. Is formed, and the counterbore peripheral surface of the labyrinth can serve as a heat-resistant wall against the heat of the combustion gas, so that the heat resistance and pressure resistance can be further improved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part showing a cylinder structure of an internal combustion engine of the present invention. The internal combustion engine 1 is configured by fitting and fastening a cylinder block 2 and a cylinder head 3 formed of a lightweight material mainly composed of aluminum.

The cylinder block 2 is formed by press-fitting a cylindrical sleeve 4 made of a material having excellent heat resistance and durability, such as ductile cast iron, to integrally form a bore. After being formed in an uneven shape, the cylinder head 2 corresponding to the uneven shape is fitted and fastened.

FIG. 2 is an enlarged cross-sectional view showing a main part of FIG. The cylinder block 2 has a fastening surface 11 at its end.
The outer peripheral surface 12 is a cylindrical fitting surface concentric with the bore, and a counterbore portion 13 for positioning the sleeve 4 is formed on the inner peripheral side of the fastening surface 11 so as to abut on the cylinder head 3 for abutment fastening. I do.

The sleeve 4 has an enlarged diameter portion 15 integrally formed at an end of the cylindrical portion 14, and the cylindrical portion 14 is connected to the cylinder block 2.
Into the cylinder block 2
And is positioned by fitting into the counterbore portion 13. The cylindrical portion 14 and the enlarged diameter portion 15 are formed into round chamfers in order to disperse the member stress.

The sleeve end surface 16 at the end of the enlarged diameter portion 15 is orthogonal to the bore axis, and the counterbore bottom surface 17 and the counterbore peripheral surface 18 form a counterbore, leaving the sleeve end surface 16 on the outer peripheral side. The sleeve end face 16 and the counterbore bottom face 17 are closely opposed to the cylinder head 3 respectively,
The counterbore peripheral surface 18 and the enlarged peripheral surface 19 on the outer peripheral side thereof are fitted to the cylinder head 3 as fitting peripheral surfaces forming a concentric cylindrical surface with the bore.

In the cylinder structure of the internal combustion engine having the above-described structure, the heat-resistant sleeve 4 is axially positioned with respect to the cylinder block 2 by the enlarged diameter portion 15.
Protects the cylinder block 2 by securing the wear resistance of the piston sliding surface, and forms a step-shaped labyrinth from the counterbore bottom surface 17 to the fastening surface 11 between the cylinder block 2 and the cylinder head 3. .

The step-shaped labyrinth from the counterbore bottom surface 17 to the sleeve end surface 16 is formed by a gap between the counterbore bottom surface 17 and the sleeve end surface 16 which enable high-precision dimensional control.
In the meantime, the counterbore peripheral surface 18 forms a long path in series,
In particular, the counterbore peripheral surface 18 effectively prevents passage of the high-pressure combustion gas in the bore since a large flow resistance is generated by the close fitting of the lightweight soft material of the cylinder head 3 and the hard material of the sleeve 4. In addition to this, the counterbore peripheral surface 18 can act as a heat-resistant wall to resist the heat of the combustion gas.

The stepped labyrinth from the sleeve end face 16 to the fastening surface 11 is strongly and closely contacted with the enlarged peripheral surface 19 which forms a fitting peripheral surface which generates a large flow resistance by close fitting. With the long path including the fastening surface 11, the passage of the high-pressure combustion gas in the bore can be effectively prevented.

Therefore, since the cylinder structure of the internal combustion engine can cope with high-temperature and high-pressure combustion due to high compression by improving heat resistance and pressure resistance, it is possible to achieve high output without reducing durability. be able to.

In the above, by forming the counterbore portion 13 of the cylinder block 2 deep, the sleeve end face 1 is formed.
Even when the connecting surface 6 and the fastening surface 11 form an inverted step, a large flow resistance according to the enlarged diameter peripheral surface 19 is secured by the fitting peripheral surface formed by the close fitting of the counterbore peripheral surface of the cylinder block 2 and the cylinder head 3. Therefore, the same operation and effect can be obtained.

FIG. 3 is a plan view of a cylinder portion to which the cylinder structure of FIG. 1 is applied, and FIG. 4 is a sectional view taken along line AA of FIG. In the configuration example of the cylinder block portion, the bores of the cylinder block 2 integrally formed with three cylinders are removed, and the sleeves 4 are press-fitted, respectively. In this way, it is possible to cope with high-temperature and high-pressure combustion due to high compression by improving heat resistance and pressure resistance. Therefore, it is possible to increase the output of a multi-cylinder engine without reducing durability. it can. In addition, the present invention has a similar effect to the water-cooled and oil-cooled internal combustion engines including the air-cooled internal combustion engine having severe temperature conditions.

[0019]

The cylinder structure of the internal combustion engine according to the present invention has the following effects. In the cylinder structure of the internal combustion engine having the above configuration, the sleeve blocks the combustion gas in the bore to protect the cylinder block, and a step-shaped labyrinth from the end face of the sleeve to the fastening face can be closely fitted to the gap of the sleeve end face. The passage of the high-pressure combustion gas in the bore can be effectively prevented by the long path including the fitting peripheral surface and the fastening surface that can be tightly fastened. Therefore, the above-described cylinder structure can cope with high-temperature and high-pressure combustion due to high compression by improving heat resistance and pressure resistance, so that high output can be achieved without lowering durability.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a cylinder structure of an internal combustion engine of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG. 1;

FIG. 3 is a plan view of a cylinder unit to which the cylinder structure of FIG. 1 is applied;

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a sectional view of a main part of a conventional internal combustion engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder block 3 Cylinder head 4 Sleeve 11 Fastening surface 12 Outer peripheral surface 14 Cylindrical part 15 Large diameter portion 16 Sleeve end surface 17 Counterbore bottom surface 18 Counterbore peripheral surface (fitting peripheral surface) 19 Large diameter peripheral surface (fitting peripheral surface) )

Claims (2)

[Claims] 1. A cylinder block having a bore formed therein and a cylinder head which closes an end thereof and seals combustion gas are formed of a so-called lightweight material, and a cylinder block is formed at an end of the cylinder block at right angles to a bore axis. In the cylinder structure of an internal combustion engine in which a cylinder head is abutted and fastened, a cylindrical sleeve made of a heat-resistant material is press-fitted into the cylinder block, and the end of the sleeve forms an enlarged portion for press-fitting and positioning in the bore axis direction. Forming a step from the fastening surface at the end to form a sleeve end surface perpendicular to the bore axis,
The end face of the sleeve is close to the opposing face of the cylinder head, and a fitting peripheral face is formed between the end face of the sleeve and the fastening face so as to closely fit with the cylinder head at a constant radius from the center of the bore. Cylinder structure of an internal combustion engine. 2. A counterbore bottom surface perpendicular to the bore axis and a counterbore peripheral surface having a constant radius from the center of the bore are formed in a counterbore shape, leaving the outer peripheral side of the sleeve end surface, and the counterbore bottom surface is opposed to the cylinder head. Close to the surface,
2. The cylinder structure for an internal combustion engine according to claim 1, wherein the counterbore peripheral surface is closely fitted to the cylinder head.