Piston ring assembly

Claim 2

A piston ring assembly comprising an annular parted expansion ring having an axial piston ring bearing portion; and an annular parted piston ring disposed substantially circumferentially around said expansion ring and having an outer annular portion and an inner annular portion, the latter having a predetermined segment thereof in bearing contact with the bearing portion of said expansion ring; said inner annular portion being provided with at least one circumferential recess spaced generally radially outwardly from and in non-bearing relationship with the bearing portion of said expansion ring.

Claim 3

A piston ring assembly as in claim 1 wherein said expansion ring has a sinusoidal corrugated configuration.

Claim 4

A piston ring assembly as in claim 1 wherein said expansion ring has a helical coiled configuration.

Claim 5

A piston ring assembly as in claim 1 wherein said outer annular piston ring portion includes at least one radially outwardly extending circumferential protuberance.

Claim 6

A piston ring assembly as in claim 4 wherein said piston ring includes a pair of axially separated protuberances coacting to form an outer circumferential channel.

Claim 7

A piston ring assembly as in claim 5 wherein said channel includes a base surface having formed therein a plurality of circumferentially spaced ports.

Claim 8

A piston ring assembly as in claim 1 wherein said inner piston ring portion includes a radially inwardly extending shoulder superposed said expansion ring.

Claim 9

A piston ring assembly as in claim 1 wherein said inner piston ring portion includes a radially inwardly extending shoulder subtending said expansion ring.

Claim 10

A piston ring assembly as in claim 1 wherein said inner piston ring portion includes two radially inwardly extending shoulders between which said expansion ring is disposed.

Claim 11

A piston ring assembly as in claim 1 wherein said circumferential recess comprises a single groove substantially axially centered of said inner piston ring portion.

Claim 12

A piston ring assembly for placement between a piston and a cylinder wall, said assembly comprising an annular parted expansion ring encompassing said piston and disposed within a continuous groove formed in the exterior surface of said piston; and an annular parted piston ring encompassing said expansion ring and having an outer annular portion in sliding substantially sealing engagement with said cylinder wall, and an inner annular portion in bearing engagement with a predetermined segment of the bearing portion of said expansion ring; said inner portion including at least one groove spaced generally radially outwardly from and in non-bearing relation with the bearing portion of said expansion ring and extending substantially circumferentially in opposite directions from a part formed in said piston ring.

Claim 13

A piston ring assembly for placement between a piston and a cylinder wall, said assembly comprising an annular parted expansion ring encompassing said piston and disposed within a continuous groove formed in the exterior surface of said piston; and an annular parted piston ring encompassing said expansion ring and having an outer annular portion in sliding substantially sealing engagement with said cylinder wall, and an inner annular portion in bearing engagement with a predetermined segment of the bearing portion of said expansion ring; said inner portion including at least one groove spaced generally radially outwardly from and in non-bearing relation with the bearing portion of said expansion ring and extending substantially circumferentially in opposite directions from a part formed in said piston ring.

Claim 14

A piston ring assembly comprising an annular sinusoidally corrugated expansion ring having an outer axial bearing portion; and an annular parted piston ring encompassing said expansion ring and having an outer annular portion including two radially outwardly extending circumferential protuberances axially separated and an inner annular portion bearing at least in part against the outer axial bearing portion of said expansion ring, said inner portion being provided with a recess in which the outer axial bearing portion of said expansion ring is disposed, and at least one circumferentially continuous groove being formed in the base of the recess and in non-bearing relation with said expansion ring.

Claim 15

A piston ring assembly comprising an annular sinusoidally corrugated expansion ring having an outer axial bearing portion; and an annular parted piston ring encompassing said expansion ring and having an outer annular portion including two radially outwardly extending circumferential protuberances axially separated and an inner annular portion bearing at least in part against the outer axial bearing portion of said expansion ring, said inner portion being provided with a recess in which the outer axial bearing portion of said expansion ring is disposed, and at least one circumferentially continuous groove being formed in the base of the recess and in non-bearing relation with said expansion ring.