JPH1037797A - Structure of cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the cooling loss resulting from an excessive water-cooling jacket and lower noises generated from an engine. SOLUTION: A cylinder block concerned is provided with a water-cooling jacket 4 furnished with a cooling water passage 5 surrounding the periphery of the bore wall 3 constituting a cylinder bore 2 in the range from the top of the bore wall 3 to a position near the top surface of a piston positioned at the lower dead point, and the external wall 7 of the jacket 4 is extended in such a way as spreading smoothly downward in such a condition that a space 16 is reserved with respect to the lower part of the bore wall 3 and is continued to a skirt part 15 provided in the lower part of the cylinder block 1. Thus the jacket 4 is locatated in the proper range to ensure elimination of the cooling loss, and at the same time, leakage of the engine noise to the outside is suppressed by the external wall 7 to accomplish a low noise emission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cylinder block, and more particularly to a structure of a cylinder block in which cooling loss is reduced and engine noise is reduced.

[0002]

2. Description of the Related Art A conventional cylinder block generally has a structure as disclosed in, for example, Japanese Utility Model Laid-Open No. 57-58746. Referring to FIG. 3, a cooling water passage 23 surrounding the periphery of the bore wall 22 forming the cylinder bore 21 over the range from the upper end to the lower end is formed between the bore wall 22 and the outer wall 24. 2
A water-cooling jacket 25 is formed by the outer wall 2 and the outer wall 24. A flared skirt portion 26 forming a crank chamber extends from the lower end of the outer wall 24 of the water cooling jacket 25.

Incidentally, the bore wall 22 must be provided over the entire length of the vertical movement of the pinton, that is, the range between the upper end surface of the piston at the top dead center and the lower end of the piston at the bottom dead center. The part of the bore wall 22 that needs to be cooled particularly is in a range directly in contact with the almost hot combustion gas, that is, in a range between the upper end of the bore wall 22 and a position near the upper end surface of the piston at the bottom dead center. If the water cooling jacket 25 is provided over the entire length of the bore wall 22, there is a problem that conversely, a cooling loss occurs, and a film vibration is induced on the outer side wall 24 to promote engine noise.

Therefore, as shown in FIG. 4, a water cooling jacket 25 is provided around the upper portion of the bore wall 22, that is, in the range between the upper end of the bore wall 22 and the position near the upper end surface of the piston at the bottom dead center. A configuration in which a flared skirt portion 26 forming a crank chamber extends from the lower end of the bore wall 22 has been proposed.

[0005]

However, in the structure shown in FIG. 4, the lower portion 22a of the bore wall 22 is used as it is as the outer wall of the cylinder block.
From 2a, there is a problem that noise such as an explosion sound in the cylinder bore 21 easily leaks out as radiated sound or transmitted sound, and engine noise increases.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a structure of a cylinder block capable of reducing engine noise without causing cooling loss due to an excessive water cooling jacket.

[0007]

According to the present invention, there is provided a cooling water passage surrounding a bore wall forming a cylinder bore in a range between an upper end of the bore wall and a position near a piston upper end surface at a bottom dead center. A water-cooled jacket is provided, and the outer wall of the water-cooled jacket is smoothly extended downward and downward in a state where a space is provided between the outer wall and the lower part of the bore wall, and is continuously connected to a lower skirt portion of the cylinder block.
As a result, a water cooling jacket is provided in an appropriate range to eliminate cooling loss, and engine noise is leaked to the outside at the outer wall provided with a space around the lower part of the bore wall where the water cooling jacket is not provided In addition, the outer wall of the cylinder block is smoothly extended in a divergent shape and connected to the skirt portion, thereby eliminating a sudden cross-sectional change and increasing the rigidity of the lower structure of the cylinder block.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

Reference numeral 1 denotes a cylinder block of a multi-cylinder engine, in which a plurality (three in the illustrated example) of cylinder bores 2 are arranged in a line. Reference numeral 3 denotes a bore wall of each cylinder bore 2. Reference numeral 4 denotes a water-cooled jacket formed so as to surround the periphery of the upper part of each bore wall 3. This water-cooled jacket 4
Is a range from the upper end of the bore wall 3 to a position near the upper surface of the piston when a piston (not shown) moving up and down in the cylinder bore 2 is located at the bottom dead center.

The water-cooled jacket 4 has cylinder bores 2.
A substantially uniform width main cooling water passage 5 formed between each bore wall 3 and the outer wall 7 so as to surround the periphery of the row, and between the adjacent bore walls 3, 3 between the cylinder bores 2, 2. The auxiliary cooling water passage 6 is formed so as to communicate with the main cooling water passages 5 on both sides. Reference numeral 8 denotes an opening formed so as to open from an appropriate position of the water-cooling jacket 4 to the upper surface of the cylinder block 1 and is used as a core sand discharge port for a core for forming a water-cooling jacket. This is used as a cooling water outflow hole through which a cooling water in the water cooling jacket 4 flows out toward the cylinder head through a through hole formed in a gasket interposed between the gasket.

Reference numeral 9 denotes a pump casing formed on one side of one end face of the cylinder block 1, and a suction passage 10 extends toward the inner side (the other end of the cylinder block). The suction passage 10 has an opening 10a on the upper surface of the cylinder block 1, and is connected to an outlet of a cooling water passage formed in a cylinder head (not shown). Reference numeral 11 denotes a discharge port of the pump casing 9, which communicates with one side of a portion of the main cooling water passage 5 located at one end of the cylinder block 1. The cylinder block 1 in the main cooling water passage 5
A protrusion 12 projecting from the outer wall 7 into the main cooling water passage 5 protrudes from a portion positioned at one end of the main cooling water passage 5. Is prevented from flowing toward the other side in the direction opposite to the direction of the arrow in the figure, and the cooling water is configured to flow smoothly in one direction. Further, a required gap 13 is formed between the projection 12 and the bore wall 3 so as not to restrict the thermal expansion and contraction of the bore wall 3.

In the main cooling water passage 5, a discharge port 1 is provided.
1, that is, along the one side of the cylinder block 1, at the portion 14 near one side of the sub-cooling water passage 6 and on the upstream side in the flow direction of the cooling water, the center of curvature of the outer wall 7. Is decentered by an appropriate distance d with respect to the center of the cylinder bore 2, so that the outer wall 7 gradually approaches the bore wall 3 as it approaches one side of the sub cooling water passage 6. In FIG. 1, the imaginary line indicates the shape of the normal outer wall 7. With this configuration, part of the cooling water flowing through the main cooling water passage 5 is directed toward the sub cooling water passage 6, and the cooling water surely flows into the sub cooling water passage 6.

The main cooling water passage 5 of the water cooling jacket 4
As shown in FIG. 2, the outer wall 7 extends smoothly downward and divergently downward, and continues to the skirt portion 15 at the lower portion of the cylinder block 1. Accordingly, a space 16 is formed between the outer wall 7 and the lower part of the bore wall 3, and the lower part of the bore wall 3 and the outer wall 7 are connected by a reinforcing rib 17 crossing the space 16. I have.

According to the above configuration, when the engine is operated and the water pump is operated, the cooling water flowing out from the discharge port 11 of the pump casing 9 passes through the water cooling jacket 4 and cools the bore wall 3 of each cylinder bore 2. After that, it flows out from the opening 8 on the upper surface of the cylinder block 1 toward the cylinder head (not shown), cools the exhaust side of the cylinder head, flows out toward the radiator, and the cooling water cooled by the radiator After cooling the intake side of the cylinder head, it flows into the suction passage 10 of the pump casing 9. The circulation of the cooling water cools the cylinder block 1 and the cylinder head.

In the water cooling jacket 4 of the cylinder block 1, the cooling water flows in one direction through a main cooling water passage 5 having a substantially uniform width formed so as to surround the cylinder bores 2. A portion of the bore wall 3 facing the main cooling water passage 5 is effectively cooled by the cooling water, and a portion of the main cooling water passage 5 located at one end of the cylinder block 1 is connected to the main cooling water passage from the outer wall 7. 5 has a protrusion 12 protruding into the discharge port 1.
The cooling water flowing out of 1 flows smoothly in one direction without flowing in the main cooling water passage 5 in the opposite direction toward the other side,
High cooling performance can be secured without causing stagnation in the flow of cooling water in the main cooling water passage 5. Further, since the gap 13 exists between the protrusion 12 and the bore wall 3, the thermal expansion and contraction of the bore wall 3 is not restricted, so that the thermal deformation of the bore wall 3 is not distorted, and as a result, the oil consumption is reduced. Reduction, seizure prevention,
In addition, mechanical loss can be reduced.

As described above, the portion of the bore wall 3 facing the main cooling water passage 5 is effectively cooled by the smooth flow of the cooling water in the main cooling water passage 5 in one direction. Since the outer wall 7 of the portion 14 near the one side of the sub-cooling water passage 6 and on the upstream side in the flow direction of the cooling water is gradually approached to the one side of the sub-cooling water passage 6, Part of the cooling water flowing through the main cooling water passage 5 reliably flows into the sub cooling water passage 6 between the adjacent bore walls 3, 3.
The portion of the bore wall 3 facing the sub cooling water passage 6 is also reliably cooled. Therefore, the temperature of the bore wall 3 can be kept uniform over the entire circumference, and the thermal deformation of the bore wall 3 does not become irregular. As a result, it is possible to reduce oil consumption, prevent seizure, and reduce mechanical loss. it can.

The water cooling jacket 4 is provided in a range from the upper end of the bore wall 3 to a position near the upper surface of the piston when the piston is at the bottom dead center, and the water cooling jacket 4 is provided only in an appropriate range. Since the cooling loss can be eliminated, and the outer wall 7 of the water-cooled jacket 4 extends smoothly downward and divergently, and continues to the lower skirt portion 15 of the cylinder block 1,
The outer wall 7 is provided with a space 16 around the lower part of the bore wall 3 where the water cooling jacket 4 is not provided, and it is possible to suppress the leakage of the engine noise to the outside, thereby exhibiting the effect of reducing the noise. Further, since the structure is smoothly continued to the skirt portion 15 and there is no abrupt cross-sectional change, the rigidity of the lower structure of the cylinder block 1 can be improved, the wall thickness can be reduced by that much, and the weight can be reduced. Because of the shape, in the casting process of the cylinder block 1, there is an effect that the running of the molten metal is improved, the core is easily removed, and the external shape of the cylinder block 1 is refreshed.

In the above embodiment, the present invention is applied to a main cooling water passage 5 formed so as to surround the periphery of a row of cylinder bores.
An example is shown in which the present invention is applied to the water cooling jacket 4 having the sub cooling water passage 6 between the cylinder bores 2 and 2.
The same effect can be obtained even if the present invention is applied to a cyme meal cylinder block in which no is formed.

[0019]

According to the structure of the cylinder block of the present invention, the periphery of the bore wall forming the cylinder bore as described above extends over the range between the upper end of the bore wall and the position near the upper end face of the piston at the bottom dead center. Since the water cooling jacket that constitutes the surrounding cooling water passage is provided, the cooling loss can be eliminated by providing the water cooling jacket only in an appropriate range, and the space between the outer wall of the water cooling jacket and the lower part of the bore wall is provided. The engine noise is leaked to the outside on the outer wall that is spaced around the lower part of the bore wall where the water cooling jacket is not provided. The engine noise can be reduced by suppressing it, and the outer wall extends smoothly and divergently so as to be continuous with the skirt. The rigidity of the lower structure of the block can be increased, the wall thickness can be reduced by that much, and the weight can be reduced. The cylinder block can be easily removed, and the outer shape of the cylinder block can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall cross-sectional plan view of a cylinder block according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view taken along line AA of FIG.

FIG. 3 is an overall cross-sectional plan view of a conventional cylinder block.

FIG. 4 is an overall cross-sectional plan view of another conventional cylinder block.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder bore 3 Bore wall 4 Water cooling jacket 5 Main cooling water passage 7 Outer side wall 15 Skirt part 16 Space

Claims (1)

[Claims] 1. A water cooling jacket comprising a cooling water passage surrounding a bore wall forming a cylinder bore over a range between an upper end of the bore wall and a position near an upper end surface of a piston at a bottom dead center. Characterized in that the outer wall of the cylinder block extends smoothly downward and divergently downward with a space provided between the outer wall of the cylinder block and the lower portion of the bore wall, and is connected to the lower skirt portion of the cylinder block. Construction.