| 摘要 |
PURPOSE:To improve the rigidity against torsion by forming a crank lower case, which is connected to the underside of a cylinder block, out of a solid grating lower case frame and a thin plate member connected to its right and left outer sides. CONSTITUTION:A lower case frame C connected integrally to the underside of a cylinder block BC provided with cylinder barrels 101-104 is formed out of a solid grating lower case frame 34 and a thin plate member, which is not illustrated, provided on its right and left outer sides. The lower case frame 34 consists of plural horizontal beam aggregates 37, 371, plural vertical aggregates 38, 381 which connect their outer edges integrally in the direction of the axial line of a crank, and plural column aggregates 39, 391 which connect the outer edges of the horizontal beam aggregates 37, 371 integrally in the stroke direction of a piston 5. Moreover, the above thin plate member is provided on the outer sides of the vertical beam aggregates 38, 381 and the column aggregates 39, 391. |
