Cast hollow crankshaft and method of manufacturing the same

Abstract

The present invention provided a cast hollow crankshaft in the foundry of the internal-combustion engine and method of manufacturing the same. A cast hollow crankshaft reduced in weight by hole casting, accurately manufactured with high productivity by eliminating the deflection of a core in manufacturing and the rise of the core in pouring molten metal, and eliminating the need of boring oil holes and a method of manufacturing the crankshaft. In the crankshaft, the hollow part section of a journal part and / or a pin part is formed in an elliptic shape, and oil holes in the journal part and pin part are formed by casting with the core. The hollow part section of an arm part is also formed in an elliptic shape. The core of elliptic shape used in the method is bent in the horizontal direction and has a vertical major axis part in its cross section at the journal part and / or the pin part. The core bent in the horizontal direction and having a plurality of core print parts extending toward a mold or a plurality of core print parts extending toward the mold in the vertical direction at the journal part and / or the pin part is hole-cast to integrally form the hollow part and the oil holes with each other.

Description

technical field [0001] The invention relates to a cast hollow crankshaft for an internal combustion engine. More specifically, the present invention relates to a hollow crankshaft in which a part around its axis is cored out at the time of casting, and to a method of manufacturing the above-mentioned hollow crankshaft. Background technique [0002] For an internal combustion engine, more mileage and higher performance are desired while consuming the same amount of fuel. For the crankshaft, reduced weight and low friction are desired. Furthermore, it is currently necessary to simplify the manufacturing process in order to reduce costs. Typically, ductile iron is used to cast crankshafts. However, in this case, the overall weight of the crankshaft increases because the crankshaft diameter or the like must be made large to ensure mechanical performance. This poses the problem of an increase in the required torque when, for example, the internal combustion engine is started....

AI Technical Summary

Problems solved by technology

[0008] However, unlike the aforementioned method using casting, the aforementioned method using machining cannot significantly reduce the weight of the crankshaft

In addition, since the cylinder block is made of aluminum, the clearance of the journal portion increases due to the difference in thermal expansion, and the leakage of oil increases when oil is supplied from the journal portion to the crankshaft.

Therefore, the oil supply efficiency decreases

In addition, the aforementioned method using machining requires a different process, that is, a process of forming the oil hole obliquely from the journal to the rod bearing

Therefore, from manufacturing and cost considerations, the method of machining is not preferred

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