Piston for internal combustion engine

Abstract

To form an internal combustion engine piston for high speed rotation by realizing a lightweight, compact structure. A top ring groove 2 and an oil ring groove 4 are formed in a circumferential part of a crown part 1, and lubricating holes 5 are provided at inner parts of the oil ring groove 4. A pair of piston boss parts 6 are provided at mutually facing positions under the crown part 1 to be continuous with it, and a skirt part 7 is provided at 90 DEG C. to it. A lower end 12 of the skirt part 7 is set above a lower end 11 of the piston boss part 6, and lubricating holes 10 are provided above the skirt part 7, and under and close to the oil ring groove 4.

Description

technical field [0001] The present invention relates to a piston for an internal combustion engine, and more particularly to a piston for an internal combustion engine suitable for high rotational speed and compactness. Background technique [0002] Existing pistons for internal combustion engines have a crown, a piston pin seat integrally formed with the crown, and a pair of skirts oppositely arranged, and grooves for piston rings are formed around the crown (as an example, refer to Japan Real Fair 7-7570). FIG. 6 shows such a conventional structure. A first gas ring groove 2, a secondary ring groove 3, and an oil groove 4 are provided around the crown portion 1, and piston rings omitted from the figure are respectively fitted in them. The bottom of the oil ring groove 4 is formed with an oil supply hole 5 penetrating inside and outside. [0003] Reference numeral 6 is a piston pin seat portion, 7 is a skirt portion, and the lower end of the skirt portion 7 extends downwa...

AI Technical Summary

Problems solved by technology

[0005] However, when the lower part of the skirt 7 protrudes much downward as in the example of the prior art as described above, the weight is increased by it, and therefore, there is a problem that it hinders the high rotation speed or compactness of the engine.

The same problem also exists when the circumferential width of the skirt is large

[0006] In addition, if sufficient lubrication cannot be provided even if an oil supply hole is provided on the bottom of the oil ring groove, the friction between the piston and the cylinder will become severe, and sometimes the piston will be stuck or burnt.

[0007] In addition, although the step portion 8 for machining reference is provided at the lower portion of the skirt portion 7, under the condition that the skirt portion 7 is subjected to a high load, the step portion 8 may become a starting point of fracture due to stress concentration.

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