| 摘要 |
PROBLEM TO BE SOLVED: To minimize a measurement error in an engine-friction force measuring instrument for measuring the frictional force acting between a cylinder sleeve and a piston. SOLUTION: A sealing member 25 for sealing between a cylinder head 3 and the cylinder sleeve 4 is held, by abutting against an inner circumferential surface of the cylinder sleeve by an elastic restoring force; the cylinder head is provided with a protrusion protruding into the cylinder sleeve; an outer circumferential surface of the protrusion is provided with a circumferential-direction groove; and the sealing member is accepted by the circumferential-direction groove, having a gap between the sealing member and a bottom face of the circumferential-direction groove. The sealing member is abutted against the inner wall of the circumferential-direction groove on the cylinder head side, in a direction in which a cylinder internal pressure is applied to the sealing member, and sealability is secured by abutting. Since abutting direction becomes a pressure-biasing direction of the cylinder internal pressure to the cylinder head, the load from the cylinder head by the cylinder internal pressure (the pressure biasing direction) can be inhibited from being conveyed to the cylinder sleeve via the sealing member, and higher accuracy for the friction force measurement is obtained. COPYRIGHT: (C)2011,JPO&INPIT
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