JPH1113533A - Cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve processing precision of a barrel wall inner surface, and attain high efficiency in an engine by reducing the wall thickness of a part when the rigidity of a barrel wall becomes higher which forms a cylinder barrel previously before the final processing of the barrel wall inner surface. SOLUTION: A groove 10 extending in an axial direction of a cylinder barrel 1 is formed in the vicinity of a part A between a through hole 81 and a through hole 82 positioned below the left side of a top deck 7 in a barrel wall 4 which forms a siamese cylinder barrel 6. The depth of the groove 10 is formed so as to become deeper as it approaches the top deck 7 for uniformizing the rigidity of the barrel wall 4. It is thus possible to improve the processing precision of the barrel wall inner surface 4a, which is represented especially by roundness. The clearance between a piston ring and the barrel wall inner surface 4a can be formed so as to be small and uniform, thereby reducing the leakage or sliding resistance generated between the barrel wall inner surface 4a and the piston ring. It is thus possible to attain high efficiency in an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block having a water jacket for liquid cooling provided around a cylinder barrel, and more particularly to a cylinder block having a structure capable of contributing to an improvement in cylinder barrel machining accuracy after casting. .

[0002]

2. Description of the Related Art A cylinder block of an engine is usually formed by casting. Therefore, in the cylinder block, the inner surface of the barrel wall constituting the cylinder barrel is polished by a honing process or the like after casting, and the inner diameter of the barrel wall or the true diameter is adjusted so that the piston ring can slide without a gap. Circularity or surface roughness must be within the set value.

In a cylinder block having a water jacket for liquid cooling provided around a cylinder barrel, a barrel wall constituting the cylinder barrel has
There may be structural differences in partial rigidity.
For example, in a cylinder block having a siamese cylinder barrel as described in Japanese Utility Model Application Laid-Open No. Sho 62-171643, a portion of the barrel wall between the cylinder barrels has high rigidity due to its structure. The portion facing the water jacket has low rigidity. Further, even if the wall thickness of the barrel wall is uniform, a partial difference occurs in the rigidity of the barrel wall due to the shape of the top deck. To give a specific example, if a plurality of through-holes or the like communicating with the water jacket are provided in the top deck, the rigidity of the barrel wall near the portion where these through-holes are present becomes low. On the contrary, the rigidity of the barrel wall near the portion having no through hole is increased.

[0004]

However, in recent years,
In promoting high efficiency of the engine, which is particularly important, the gap between the inner surface of the barrel wall and the piston ring is made more uniform and smaller, and the leakage and sliding generated between the inner surface of the barrel wall and the piston ring are increased. It is necessary to reduce dynamic resistance. However, if the barrel wall has a partial rigidity difference as described above, the expected dimensional accuracy may not be obtained when the inner surface is polished by honing or the like. That is, at the time of the honing process, a portion of the barrel wall having a low rigidity escapes to the outside and is not polished, and a high rigid portion is polished more. As a result, there is a problem in that the roundness cannot be improved beyond a certain value, for example, the cross-sectional shape of the inner surface of the barrel wall becomes a vertically long or horizontally long circle after processing.

Therefore, it is easily conceivable to increase the rigidity of the barrel wall by adding a reinforcing member such as a rib to the low rigidity portion. However, in this method, it is actually necessary to provide ribs uniformly over the entire circumference of the barrel wall, and to change the shape of some of the ribs so as to make the rigidity uniform, thereby reducing the weight of the cylinder block. The problem that it leads to increase arises. Further, there is a problem in that the core forming the water jacket becomes thinner by the amount of the ribs, and it becomes difficult to secure the rigidity of the core required during casting.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems at once, the present invention provides a method in which the rigidity of a high-rigidity portion of a barrel wall is made closer to the rigidity of a low-rigidity portion. It is an object of the present invention to provide a cylinder block having a structure capable of obtaining processing accuracy of an inner surface of a barrel wall corresponding to high efficiency of an engine.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a cylinder block for an internal combustion engine having a water jacket for liquid cooling provided around a cylinder barrel, in which a barrel wall forming the cylinder barrel has a high rigidity. Is characterized in that the wall thickness is previously reduced before the final processing of the inner surface of the barrel wall.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The cylinder block 3 according to the present embodiment includes, for example, as shown in FIGS. 1 to 3, a siamese cylinder barrel 6, a water jacket 2, a top deck 7,
It comprises a cylinder block main body 5 and is formed by casting.

The siamese cylinder barrel 6 is formed by connecting a plurality of cylinder barrels 1 with a coarse material to make the cylinder barrel 1 compact. In this embodiment, for example, three cylinder barrels 1 are connected as shown by hatched portions in FIG. The water jacket 2 shown in FIGS. 2 and 3 is a cavity provided so as to surround the siamese cylinder barrel 6 as is generally widely known. The cavity is filled with a cooling liquid, The liquid is circulated by a water pump (not shown) to cool the engine.

The top deck 7 is located on the uppermost surface of the cylinder block 3 and includes a plurality of through holes 81 to 814 communicating with the water jacket 2 and an oil drop hole 9. The plurality of through holes 81 to 814 serve as communication paths for feeding the cooling liquid to a cylinder head (not shown) mounted on the top deck 7.

In this embodiment, as shown in FIGS. 2 and 3, the barrel wall 4 forming the siamese cylinder barrel 6 has a through hole 81 located at the lower left of the top deck 7 in FIG. A groove 10 extending in the axial direction of the cylinder barrel 1 is provided integrally at the time of casting near the portion A between the hole 82. Specifically, as shown in FIG. 3, the groove 10 is provided on the outer surface side of the barrel wall 4, that is, on the side facing the water jacket 2, and the lower surface 7 of the top deck 7
At a, the depth becomes the deepest, and the depth decreases as the distance from the top deck 7 increases. In addition,
The groove 10 has, for example, a partial arc shape in cross section.

The reason why the groove 10 is provided near the portion A between the through hole 81 and the through hole 82 is that the groove 10 is formed in the barrel wall 4 near the portion A in the siamese cylinder barrel 6 of this embodiment. If the wall thickness is equal to the surrounding wall thickness,
This is because the rigidity of the nearby barrel wall 4 is particularly high as compared with the surroundings. That is, as shown in FIG.
In order to ensure the area occupied by the oil gasket to be mounted in the oil drop hole 9, the area cannot be reduced in distance between the through holes as in other parts, and must be considerably large. Since the oil drop hole 9 is formed after the honing of the inner surface 4a of the barrel wall due to the manufacturing process, the oil drop hole 9 exists as a very rigid solid column before the honing. ing. as a result,
As shown in the left part B of FIG. 3, the oil drop hole 9 (a solid pillar before processing) is more directly connected to the barrel wall 4 by the portion A of the top deck 7 where there is no through hole. That is, the rigidity of the barrel wall 4 near the portion A is higher than that of the surroundings. For comparison, in the right portion C of FIG. 3, the through hole 813 prevents direct connection between the barrel wall 4 and the cylinder block body 5 outside the barrel wall 4, and the barrel wall 4 in this portion The rigidity of 4 does not increase.

Therefore, in the present embodiment, the groove 10 is provided near the portion A of the top deck 7 in the barrel wall 4, and the depth of the groove 10 increases as approaching the top deck 7. The stiffness was made uniform. That is, according to the above-described embodiment, it is possible to improve the processing accuracy of the barrel wall inner surface 4a particularly represented by the roundness. That is, the gap between the piston ring (not shown) and the inner surface 4a of the barrel wall can be made smaller and more uniform, and the leakage and sliding resistance generated between the inner surface 4a of the barrel wall and the piston ring can be reduced. Can be achieved.

Further, the thickness of the water jacket 2 is increased by the height of the groove 10, and as a result, the water jacket 2
The core (not shown) required for casting the steel can be made thicker. That is, the rigidity of the core can be improved, and an additional effect that casting can be made easier can be obtained. Further, from the viewpoint of reducing the variation in the partial rigidity of the barrel wall 4, it is easily conceivable to increase the low rigidity portion of the barrel wall 4. However, in manufacturing, it is more difficult to add a reinforcing member such as a rib than to provide a groove or the like, and there is a problem that the weight of the cylinder block 3 is increased. That is, according to the present embodiment, there is also an effect that variation in the partial rigidity of the barrel wall 4 can be reduced without making the production difficult and increasing the weight.

The present invention is not limited to the above-described embodiment, but can be variously modified. For example, the position where the groove is provided is not limited to that of the embodiment, but may be any position that makes the rigidity of the barrel wall uniform according to the shape of various cylinder blocks. For the purpose of reducing the thickness of the barrel wall, the same effect as that of the present embodiment can be obtained by adopting a structure in which, for example, a plurality of recessed holes are provided other than providing the groove. Needless to say, the cylinder barrel is not limited to the siamese type.

In addition, the configuration of each section is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0017]

The present invention is embodied in the form described above and has the following effects. That is, since the wall thickness of the portion where the rigidity of the barrel wall forming the cylinder barrel is high is reduced in advance before the final processing of the inner surface of the barrel wall, the variation in the partial rigidity of the barrel wall can be reduced, and especially the roundness is reduced. , It is possible to improve the processing accuracy of the inner surface of the barrel wall. As a result, the gap between the piston ring and the inner surface of the barrel wall can be made smaller and more uniform,
It is possible to improve the efficiency of the engine.

Also, since the wall thickness of the barrel wall is reduced,
By increasing the thickness of the core, the rigidity can be improved and casting can be made easier.Furthermore, in the direction of reducing the wall thickness of the barrel wall, the rigidity of the entire barrel wall is made uniform Therefore, there is also an effect that the weight of the cylinder block is not increased and the production is not difficult.

[Brief description of the drawings]

FIG. 1 is a schematic overall perspective view of a cylinder block showing one embodiment of the present invention.

FIG. 2 is a schematic plan view of the cylinder block of the embodiment.

FIG. 3 is a partial sectional view taken along line XX in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder barrel 2 ... Water jacket 3 ... Cylinder block 4 ... Barrel wall 4a ... Barrel wall inner surface

Claims (1)

[Claims] In a cylinder block for an internal combustion engine having a water jacket for liquid cooling provided around a cylinder barrel, the wall thickness of a portion of the barrel wall forming the cylinder barrel, where the rigidity of the barrel wall is increased, is set to the inner surface of the barrel wall. A cylinder block characterized in that the cylinder block is reduced in advance before final machining of the cylinder block.