JPS5996457A - Cylinder block for internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce distortion of sleeve by making the portion of sleeve in cylinder block subjected to high temperature thick with such material having lower thermal expansion factor than cylinder block. CONSTITUTION:A sleeve 11 is composed of iron system metallic material having low thermal expansion factor and high rigidity such as cast iron or Ni-Cr system and formed integrally with a thick section 13. The portion near to top dead point subjected to high temperature is made thick while the portion near to the bottom dead point is made same thickness with lower half section. Consequently distorsion of sleeve can be reduced while displacements are ballanced to reduce cylindricality thus to improve the following performance of piston ring and to reduce oil consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder block that constitutes an internal combustion engine such as an automobile engine.

Cylinder blocks for automobile engines are generally made of aluminum alloy to reduce weight, and as shown in Fig. 1, the inner part of the cylinder barrel 1 is made of a ferrous metal, such as cast iron, as a sleeve 2 for sliding contact with the piston ring. It has increased wear resistance against gold.

By the way, as shown in the figure, the conventional sleeve 2 has a uniform thickness, but when an engine is driven, the temperature and pressure distribution inside the sleeve 2 are not uniform, and for example, the thickness of the sleeve 2 is uniform. The temperature and pressure near the top dead center are higher than those near the bottom dead center.

Therefore, with a sleeve of uniform thickness, the amount of radial displacement of the sleeve in the vicinity of top dead center and bottom dead center will differ due to the above-mentioned differences in temperature and pressure distribution, and the cylindricity of the sleeve will increase, causing the piston ring to followability deteriorates, oil consumption and blow pie gas amount increase, and piston slap noise also increases.

The present invention has been made in order to overcome all the problems of the conventional art as described above.The sleeve is made of a material with a small coefficient of thermal expansion as well as the cylinder barrel, thereby reducing the amount of distortion of the sleeve, and The amount of displacement of the sleeve from top dead center to bottom dead center is balanced, and the cylindricity of the sleeve is reduced to promote piston ring followability, reducing oil consumption, proveby gas volume, and piston slap noise. The purpose of the present invention is to provide a cylinder block for an internal combustion engine.

In order to achieve such an object, the present invention aims to reduce the thickness of a sleeve provided on the inner periphery of a cylinder barrel of an aluminum alloy cylinder block at a portion exposed to high temperatures, for example, near top dead center, by reducing the wall thickness at other portions, such as near bottom dead center. Its gist is that it is thicker than that.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 7.

FIG. 2 is a longitudinal cross-sectional view of the cylinder barrel of the cylinder block according to the present invention, and the cylinder block 10 made of aluminum alloy is formed by casting a cylindrical sleeve 11 around the inner circumference of the cylinder barrel 12. and sleeve 1
1 is made of a ferrous metal material with a low thermal expansion coefficient and high rigidity, such as cast iron or Ni-Cr type, and has a thick wall part 13 formed integrally in the upper half, and a thick part 13 between it and the cylinder head. The upper end of the gasket that is in contact with the lower surface of the gasket, that is, the part exposed to high temperature near the top dead center, should be the thickest, and the total wall thickness of the part near the bottom dead center should be equal to the wall thickness of the lower half, and the wall thickness should be changed. is tapered to correspond to the temperature distribution and pressure distribution around the sleeve 11. The thick part 13 may be formed in the part where the piston ring slides, but this range is usually about 50 mm from the upper end of the sleeve 11 where the lower surface of the gasket comes into contact, and a particularly effective range is It can be said that it is within 30m+ from the upper end.

3 to 6 show other embodiments, and the embodiment shown in FIG. 3 has an upper end exposed to high temperature in the upper half of the sleeve 21, similar to the embodiment shown in FIG. 2. Part thickness (,
A tapered part 216e is formed in the vicinity of the bottom dead center, and the tapered part 21a and the lower half are continuous with a stepped part 23, and a sleeve 21 is further formed by casting around the inner peripheral part of the cylinder barrel 22. . Further, in the embodiment shown in FIGS. 4 and 5, a ring-shaped lip 31ak is formed on the outer periphery of the part of the sleeve 31 that is exposed to high temperatures, and by forming this lip 31a, it becomes a thick part. .

In particular, in the embodiment shown in FIG. 5, a lip 31bl is further formed on the outer periphery of the lip 31a. Incidentally, these sleeves 31 are formed by being cast around the inner periphery of the cylinder barrel 32. Furthermore, in the embodiment shown in FIG. 6, a substantially tapered thick part 43 is integrally formed in the upper half of the sleeve 41, and the thickness becomes gradually thinner from the upper end toward the vicinity of the bottom dead center. Irregular uneven portions 44 are formed on the outer periphery of the thick portion 43 and the lower half of the sleeve 41, and are further formed around the inner periphery of the cylinder barrel 42.

The step portion 23, lips 31a, 31b, and uneven portion 44 are as follows:
It also serves to prevent the cylinder sleeve 21.31.41 from being pulled out in the cylinder axial direction.

Figure 7 is a graph showing specific experimental results.
is a cross-sectional view of the cylinder barrel and sleeve of a conventional cylinder block, and in this cylinder block, the sleeve and cylinder barrel have a uniform thickness, and both have a thickness of 3.5 mm. B is a cross-sectional view of the cylinder block according to the present invention. The sleeve has a tapered shape from the upper end to about 67 cm, and the wall thickness at the upper end is 5 mm and the wall thickness at the lower end of the tapered part is 2 mm.
■Furthermore, the wall thickness below this tapered part is 't-2.75
For simplicity, the overall wall thickness is 1:7 ttan, and C has a tapered portion opposite to the above. As shown in the graph on the right, the amount of displacement in the radial direction of each sleeve when the temperature of the gasket interposed part, the ox end of the thumb sleeve, is 180°C, and the temperature of the lower end of the sleeve is 120°C, is as shown in the graph on the right. The displacement amount of the sleeve is 1011 m as shown by a, the cylinder block of the present invention has a radius of 4 μm as shown by the line segment, and the radius of the cylinder block of the present invention is 4 μm as shown by the line segment C. It can be seen that the amount of displacement in the direction reaches as much as 21 μm, and the cylindricity of the sleeve is the smallest in case B.

As explained above, according to the present invention, the amount of strain on the inner periphery of the cylinder barrel of an aluminum alloy cylinder block is reduced, and the portions exposed to high temperatures, such as those near top dead center (
The total thickness of the cylinder barrel in the area is made thinner, and the total thickness of the sleeve is made thicker by that amount, so the difference in displacement of the cylinder sleeve between the high temperature area and the relatively low temperature area is reduced. Since the cylindricity of the sleeve is reduced, the followability of the piston ring is improved, and the rigidity is also improved by increasing the wall thickness of the sleeve, which has high overall rigidity in the high pressure section. Therefore, it has the advantage of being able to reduce engine oil consumption, blow-by gas, and piston slap noise without changing the thickness around the sleeve of a conventional cylinder block.

[Brief explanation of the drawing]

The drawings show a conventional example and an example of the implementation of the present invention, and FIG. 1 is a vertical cross-sectional view of a cylinder barrel of a conventional cylinder block, and FIG. 2 is a vertical cross-sectional view of seven cylinder barrels of a cylinder block according to the present invention. 3 to 6 are longitudinal sectional views showing another embodiment, and FIG. 7 is a graph comparing the cylinder block according to the present invention with a conventional example in terms of cylindricity of the sleeve. In addition, in the drawing, it, 21, 31.41 is a sleeve, 12.
22, 32, 42 are cylinder barrels, 13° 43 is a thick walled portion, 21a is a tapered portion, and 31a, 31b are lips. Figure 7

Claims (4)

[Claims] (1) The cylinder block is made of an aluminum alloy and has a sleeve on which the piston ring slides on the inner circumference of the cylinder barrel. A cylinder block for an internal combustion engine, characterized in that the wall thickness of at least a portion of the portion exposed to high temperature is thicker than the wall thickness of the portion other than the portion exposed to high temperature. (2) Claim 1, characterized in that the sleeve is formed by being cast around the inner periphery of the cylinder nozzle.
Cylinder block for an internal combustion engine as described in . (3) The internal combustion engine according to claim 1, wherein the wall thickness of the portion of the sleeve that is exposed to high temperatures gradually becomes thinner in a Teno shape from top dead center to bottom dead center. Engine cylinder block. (4) The cylinder block for an internal combustion engine according to claim 1, wherein a ring-shaped rib is integrally formed on the outer periphery of a portion of the sleeve that is exposed to high temperatures.