US 12,392,301 B2
Piston unit, top land member, and combination of piston unit parts
Hiroyuki Nagakura, Tokyo (JP); Shuichi Inamori, Tokyo (JP); and Kiyoyuki Kawai, Tokyo (JP)
Assigned to TPR Co., Ltd., Tokyo (JP)
Appl. No. 18/851,051
Filed by TPR Co., Ltd., Tokyo (JP)
PCT Filed Feb. 7, 2023, PCT No. PCT/JP2023/003944
§ 371(c)(1), (2) Date Sep. 25, 2024,
PCT Pub. No. WO2023/188834, PCT Pub. Date Oct. 5, 2023.
Claims priority of application No. 2022-052199 (JP), filed on Mar. 28, 2022.
Prior Publication US 2025/0109722 A1, Apr. 3, 2025
Int. Cl. F02F 5/00 (2006.01); F02F 3/00 (2006.01); F16J 9/12 (2006.01)
CPC F02F 5/00 (2013.01) [F02F 3/00 (2013.01); F16J 9/12 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A piston unit adapted to reciprocate in a cylinder, comprising:
a piston;
a top land member attached to the piston;
one or more ring grooves formed on an outer circumference of the piston; and
one or more piston rings fitted in a first ring groove closest to one end surface of the piston among the one or more ring grooves to slide on an inner wall surface of the cylinder,
wherein the piston includes a first portion including a piston end at a one end surface side and fitted with the top land member, the first portion having a smaller outer diameter than a second portion such that there is a step therebetween, the second portion being the other portion of the piston than the first portion,
the top land member has a slanted piston-fit surface that attaches horizontally side-by-side to an equal length tapered surface of the first portion,
the first ring groove is defined by the groove wall forming surface, the step surface, and the outer circumferential surface of the first portion,
the top land member is formed as a ring that has an annular piston-fit surface fitted to the outer circumferential surface of the first portion as an inner circumferential surface, and
wherein the piston-fit surface is slanted to have its diameter decrease as it extends upwards and the diameter of the tapered surface decreases in the same direction and fits to the outer circumferential surface of the first portion in such a way that the top land member is supported by the outer circumferential surface of the first portion from the other end surface of the piston side.