| 摘要 |
PURPOSE:To simplify a cooling device in structure, by forming such an interconnecting passage that a lower end of a crankcase is interconnected to a lubricating oil feed passage and the upper end extends as far as the vicinity of a cylinder block lower end, and installing a nozzle, spraying lubricating oil toward a piston, at the other end. CONSTITUTION:A main passage 35, where pressure oil is fed in from a hydraulic pump, is formed at the upper end of a crankcase 13, whereby lubricating oil is fed to each bush 22 from a first branch passage 35 as well as to each crankpin 20 and a joint of a connecting rod 28 from a second branch passage 38, respectively. In each partition wall to be situated at both symmetrical sides in an upper crankcase 16, there is provided with each cooling oil passage 39 being interconnected to the first branch passage 36 via a connecting oil passage 37. An upper end of the cooling oil passage 39 extends as far as the vicinity of a lower end of a cylinder block 24, and it is opened between two cylinder sleeves 25 adjoining to each other, in this opening, there is provided with nozzle 41 which sprays lubricating oil toward the lower circumference of a piston 27 through each cylinder hole 26 in these cylinder sleeves 25. |
