| 摘要 |
PROBLEM TO BE SOLVED: To effectively reduce a slap sound on the side of a piston thrust at a cold start. SOLUTION: At a cold start, lubricating oil is supplied from an oil pump, not shown, through main galleries 6LH and 6RH to a valve system of a cylinder head, not shown, a crank shaft 2, and each journal part of connecting rods 5LH and 5RH. At the same time, when viscosity of the lubricating oil is high immediately after the cold start, hydraulic pressure of the main gallery 6LH becomes high even if the rotation number of an engine is low, and a check valve 11 arranged at a second passage 7b of an oil gallery 7 for piston is opened, and the lubricating oil is supplied from an oil ejecting port 8 of a cylinder liner 3LH through the oil gallery 7 for piston from the main gallery 6LH. By this, the lubricating oil is sufficiently supplied to the thrust side of a piston 4LH on a left bank where the lubricating oil tends to run short immediately after the start, and a slap sound can be reduced by forcedly lubricating a piston skirt part.
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