| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a piston cooling device in which a cooling effect of a piston can be improved when a high load is applied and the heat loss of the piston can be reduced when a low load is applied by using a simple and low-cost means. <P>SOLUTION: A ring-shaped cooling cavity 26 is arranged inside a piston head 14a and a plurality of passages 42 for both of a lubricant and a blow-by gas are connected radially to the cooling cavity 26 in the peripheral direction. The other end of each of the plurality of passages 42 for both of the lubricant and the blow-by gas is communicated with the upper half area of an oil ring groove 25. The lubricant r flows on the wall 12 of a cylinder from the cooling cavity 26 and passing through the lower area of the passage 42 for both of the lubricant and the blow-by gas. Meanwhile, the blow-by gas g from a combustion chamber 16 intrudes into a space s between the wall 12 of the cylinder and the outside wall of the piston head, passes through the passage 42 for both of the lubricant and the blow-by gas and flows in the cooling cavity 26. Since the lubricant r and the blow-by gas g form a gas-liquid two-phase flow, the cooling effect of the piston head 14a can be improved. <P>COPYRIGHT: (C)2012,JPO&INPIT |
