INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a technology for simplifying a structure for preventing a fitting portion of a seal member interposed between a clutch shaft and a crank case from coming off, enabling replacement of the seal member from an outer side of an engine and reducing the width of the engine in the internal combustion engine in which a clutch and the clutch shaft for engaging/disengaging the clutch are arranged in the crank case.SOLUTION: A crank case 12 of an internal combustion engine 10 includes: a clutch 50; a main shaft 47 connected to the driven side of the clutch 50 and having a hollow portion 48 into which a clutch shaft 51 is inserted; and a hydraulic cylinder 52 for pressing the clutch shaft 51. A seal member 97 is interposed between the clutch shaft 51 and the crank case 12. The hydraulic cylinder 52 includes a cylinder sleeve 95 through which the clutch shaft 51 is inserted and that extends to a position adjacent to the seal member 97.