Patent ID: 11933407
Assignee: RIKEN
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F | IPC F

Claim 8:
9. A combination comprising a compression ring, a piston, and a cylinder, wherein
the compression ring is an annular compression ring having a pair of gap faces opposed to each other to form a free gap and a nominal diameter d1 equal to an inner diameter of the cylinder to which the compression ring is attached to along with the piston,
a self tangential force of the compression ring is 5 N to 50 N, and
a radius of curvature R1 and the nominal diameter d1 of the compression ring satisfy a relationship:

−0.01≤(2R1−d1)/d1<0.002

where the radius of curvature R1 is that of an outer peripheral arcs of gap end portions in a free shape state before the compression ring is attached to the cylinder, and
the gap end portions are defined in ranges between the gap faces and positions where a center angle from a midpoint of the free gap is 35°; and wherein
the compression ring has less than 35% of a light passing ratio in a light tightness test defined by ISO 6621-2:2003(E), where the light passing ratio is a ratio of a circumferential length of a light passing portion excluding the closed gap to an inner peripheral length of a ring gauge used in the light tightness test, the light passing portion being between an inner peripheral face of the ring gauge and an outer peripheral face of the compression ring.