| 摘要 |
PURPOSE:To increase compression ratio when an engine is in partially loaded operation and improve its combustion efficiency, by providing a damping piston, which changes the capacity of a subchamber on the basis of balance between pressing force by in-cylinder pressure in a combustion chamber and resilient force of a spring, and specifically setting said resilient force. CONSTITUTION:A damping piston device 5 is mounted to a part in a cylinder head 2 forming a combustion chamber 1 to be partitioned. Said device 5 has a cylinder lower 7 partitioning a subchamber 6 opened to the combustion chamber 1, damping piston 8, cylinder upper 9 brought into contact with an upper end of the cylinder lower 7 and a spring case 10. And the device 5 is constituted such that a set of springs 13, 14, resiliently mounted between a spring seat 11 in an upper end of the piston 8 and a spring seat 12 in an upper end of the case 10, are housed in the spring case 10. Resilient force of these springs 13, 14 is set so that a compression peak pressure, when an engine is in partially loaded operation, approaches the capacity increase operation starting pressure received by a pressure receiving surface of the damping piston 8.
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