| 摘要 |
<p>A partial groove (14) is formed on the inner circumferential surface of the upper bearing member (11) of a main bearing (5) which supports the main shaft (3A) of a crank shaft (3), and a spacing (D) within a range of 2mm=D=the diameter of the main shaft/3 is formed between the edge portion of the partial groove (14) and a crush relief (11b) which is formed on both edges of the upper bearing member (11) in the circumferential direction. Moreover, a depth reduction section (14b) having an arc-shaped cross section is formed on the edge portion of the partial groove (14), and the depth reduction section (14b) has a radius (r) within the range of 0=r=the radius of the inner circumferential surface of the main bearing×0.5. Additionally, a lubricant discharge path (23), which discharges a lubricant to the outside of a connecting rod (4) when connected to an internal path (3C) formed on the crank shaft (3), is disposed on a connecting rod bearing (6). As a consequence, the amount of lubricant that is discharged from the sliding section of the main bearing can be suppressed, and damages to the main bearing and the connecting rod bearing caused by foreign substances within the lubricant can be prevented as much as possible.</p> |
