| 摘要 |
PROBLEM TO BE SOLVED: To reduce tensile stress applied to a bearing cap, and reduce a weight while securing its durability.SOLUTION: When a lower block 12 is fastened to a cylinder block 11 by bolts 13 penetrating through both sides of a bearing cap 17 in a direction of a cylinder axial line L2, the bearing cap 17 is rigidly integrated with a lower block body 16 by nipping the lower block body 16 between wave-shaped protrusions 17e of the bearing cap 17, while tensile stress S1 is generated at a valley part 17g between the protrusions 17e. Also, tensile stress S2 is generated to the bearing cap 17 by explosion load F3 transmitted to a crank shaft 20. However, the protrusions 17e are provided at a position displaced from an action line L3 of the tensile stress S2, so as to prevent the tensile stress S1 due to fastening load F1 of the bolts 13 and the tensile stress S2 due to the explosion load F3 from being overlaid on each other, and lighten the bearing cap 17 while securing its durability. |
