| 摘要 |
PURPOSE:To reduce the number of main bearings by arranging in parallel a plurality of cylinder holes having an elliptical form in the direction of a shorter axis and arranging a crankshaft in parallel to a shorter axis and forming at least two cylinder holes between the main bearings on the crankshaft. CONSTITUTION:A plurality of piston holes 1 are formed onto a cylinder block 8, and each cylinder hole 1 is formed from a cylinder liner 9 fitted onto the cylinder block 8, and the sectional surface is formed into elliptical form having a longer axis 10 and a shorter axis 11. The cylinder holes 1 are arranged in straight-line form in the direction of the shorter axis 11, in parallel to the longer axis 10, and two cylinder holes 11 are approached, keeping a harrow interval (t1), and a wide interval (t2) is kept between a pair of cylinder holes 1. Though a crankshaft 4 is supported through a main bearing 5 onto a crankcase 6 internally formed with the cylinder block 8, the main bearing 5 is installed only at the both edge parts of the crankshaft 4 and the position corresponding to the wide interval (t2) part. |
