Uniform load piston ring

Claim 1

A uniform circumferential load piston ring (40), in combination with a piston (10) having a peripheral groove (11) with a downstream radially-extending wall (12B) forming one surface upon which said piston ring (40) will contact in a sealing manner; a cylinder (20) coaxially oriented with and surrounding said piston (10), with said cylinder (20) having an axially-extending peripheral surface (21) forming another surface upon which said piston ring (40) will contact in a sealing manner, wherein said piston (10) and said cylinder (20) are movable relative to each other; and, a fluid under high pressure in an annular passage (G) flowing to said groove (11) which is in communication with said passage (G); and, wherein said piston ring (40) comprises a ring body (41) having: a. a first protrusion (50) annular-shaped and extending axially from said ring body (40) in a downstream direction and forming an area of sealing contact with said downstream radially-extending wall (12B) of said piston (10), with said protrusion (50) forming a pressure relief cut, and with said protrusion (50) having an axially-extending surface (51) which is located such as to be prevented from entering said annular passage (G); b. a second protrusion (60) unsegmented, annular-shaped, and extending radially from said ring body (41), with said second protrusion (60) having an axially-extending surface (61) in contact with and forming a seal with said axially-extending inner surface (21) of said cylinder (20); c. and, a third protrusion (80) annular shaped and extending radially from said ring body (41), with said third protrusion (80) having an axially-extending surface (81) in contact with said axially-extending inner surface (21) of said cylinder (20), and with said third protrusion (80) located axially upstream of said second protrusion (60); whereby the inability of said surface (51) of said first protrusion (50) to enter said annular passage (G) assures an area of constant sealing contact between waid first protrusion (50) and said downstream radially-extending wall (12B) of groove (11), despite eccentric shifting and lateral movement between each piston (10) and said cylinder (20), thereby said load caused by said fluid under high pressure is uniformly and circumferentially distributed and exerted on said ring body (41).