Resilient plastic piston ring

Claim 2

A piston and piston ring combination for use in internal combustion engines comprising a piston having a plurality of ring grooves therein, a plurality of piston rings in said grooves, at least one of said piston rings having its inner diameter spaced from the inner diameter of a ring groove, a plastic piston ring positioned radially interiorly of said piston ring in the groove, said plastic piston ring comprising an annular ring of plastic material having inner and outer diameters and an axial thickness, an axially extending groove extending into said plastic piston ring from the top thereof, said axial groove terminating in spaced relation to the bottom of the said plastic piston ring, said groove dividing said ring into radially inner and radially outer spaced-apart portions in the area of the axial groove, the outer diameter of the radially outer portion abutting the inner diameter of the said one piston ring, the radially outer portion of the said plastic piston ring having an axial height less than the axial height of the said ring groove, and the said radially outer portion movable with respect to the radially inner portion in dependent response to the presence of a high pressure in the said axial groove.

Claim 3

The combination of claim 1 wherein the said plastic piston ring is a 360* continuous ring.

Claim 4

The combination of claim 2 wherein the said plastic piston ring is Constructed of a polyimide resin which is structurally stable at a temperature greater than 500* F.

Claim 5

A piston and piston ring combination for use in internal combustion engines comprising: a piston, at least one ring groove in said piston, said ring groove having a metal split piston ring received therein, said metal piston ring having an axial height less than the height of the ring groove, a plastic piston ring concentric with said metal ring groove, a plastic piston ring concentric with said metal ring received in said ring groove radially interiorly of said metal ring, said plastic piston ring being substantially U-shaped in cross section with the opening of the U extending upwardly, the outer diameter leg of the said U having an axial height less than the axial height of the ring groove, the inner diameter leg of the said U having an axial height greater than the outer diameter leg, said plastic piston ring bottomed in the said ring groove, the radially outer leg of the plastic piston ring circumferentially contacting the inner diameter of the said metal piston ring and the said radially outer leg movable with respect to the said radially inner leg in dependent response to the presence of pressure in the opening of the said U-shaped ring, whereby high-pressure gases entering the ring groove above the said metal piston ring will enter the said opening and press the inner diameter leg into sealing engagement with the bottom of the ring groove and the outer diameter leg into sealing engagement with the inner diameter of the metal piston ring thereby entrapping the said gas in the said ring groove.

Claim 6

A piston and piston ring combination for use in internal combustion engines comprising: a piston, at least one ring groove in said piston, said ring groove having a metal split piston ring received therein, said metal piston ring having an axial height less than the height of the ring groove, a plastic piston ring concentric with said metal ring groove, a plastic piston ring concentric with said metal ring received in said ring groove radially interiorly of said metal ring, said plastic piston ring being substantially U-shaped in cross section with the opening of the U extending upwardly, the outer diameter leg of the said U having an axial height less than the axial height of the ring groove, the inner diameter leg of the said U having an axial height greater than the outer diameter leg, said plastic piston ring bottomed in the said ring groove, the radially outer leg of the plastic piston ring circumferentially contacting the inner diameter of the said metal piston ring and the said radially outer leg movable with respect to the said radially inner leg in dependent response to the presence of pressure in the opening of the said U-shaped ring, whereby high-pressure gases entering the ring groove above the said metal piston ring will enter the said opening and press the inner diameter leg into sealing engagement with the bottom of the ring groove and the outer diameter leg into sealing engagement with the inner diameter of the metal piston ring thereby entrapping the said gas in the said ring groove.

Claim 7

The combination of claim 4 wherein the outer diameter of the said plastic piston ring is circumferentially curved in an axial direction.

Claim 8

The combination of claim 4 wherein the outer diameter of the said plastic piston ring is circumferentially tapered in an axial direction.

Claim 9

The combination of claim 4 wherein the inner diameter of the said plastic piston ring is axially tapered.

Claim 10

The combination of claim 4 wherein the inner diameter of said plastic piston ring is axially curved.

Claim 11

A piston and piston ring combination for use in internal combustion engines comprising: a piston having at least one ring groove therein, a plurality of axially thin split annulus piston rings received in said groove projecting radially beyond said groove, said piston rings positioned one atop the other in said groove, the inner diameters of said piston rings terminating in spaced relationship to the bottom of said groove, a plastic piston ring received in said groove radially inwardly of said metal piston ring, the said plastic piston ring having its inner diameter bottomed on the bottom of the ring groove and its outer diameter contacting the inner diameters of the said metal piston rings, an axially extending groove projecting into the said plastic piston ring intermediate the inner and outer diameters thereof, the said axial groove projecting into the said ring from the top axial end thereof and terminating in spaced relationship to the bottom axial end thereof, the said plastic piston ring resilient whereby the outer diameter is movable with respect to the inner diameter in dependent response to the presence of high pressure fluid in the said axial groove.

Claim 12

A piston and piston ring combination for use in internal combustion engines comprising: a piston having at least one ring groove therein, a plurality of axially thin split annulus piston rings received in said groove projecting radially beyond said groove, said piston rings positioned one atop the other in said groove, the inner diameters of said piston rings terminating in spaced relationship to the bottom of said groove, a plastic piston ring received in said groove radially inwardly of said metal piston ring, the said plastic piston ring having its inner diameter bottomed on the bottom of the ring groove and its outer diameter contacting the inner diameters of the said metal piston rings, an axially extending groove projecting into the said plastic piston ring intermediate the inner and outer diameters thereof, the said axial groove projecting into the said ring from the top axial end thereof and terminating in spaced relationship to the bottom axial end thereof, the said plastic piston ring resilient whereby the outer diameter is movable with respect to the inner diameter in dependent response to the presence of high pressure fluid in the said axial groove.

Claim 13

The combination of claim 9 wherein portions of the material of the said plastic piston ring extend from its outer diameter into the gaps in the split annulus metal rings, the said gaps being circumferentially spaced from one another whereby the said metal rings are restrained against independent rotation with respect to one another.

Claim 14

The combination of claim 10 wherein the said plastic piston ring is a 360* continuous ring constructed of a high-temperature plastic.

Claim 15

The combination of claim 10 wherein the plastic piston ring has a radial groove in the ring from its inner diameter, the said ring groove positioned intermediate the axial ends of the said plastic piston ring.

Claim 16

The combination of claim 12 wherein the said plastic piston ring has a second axial extending groove positioned intermediate the inner and outer diameters thereof extending into the ring from the bottom axial end thereof and the said radial groove and axial groove bottom in spaced relationship from one another.

Claim 17

In an internal combustion engine having at least one piston reciprocatingly positioned in a cylinder, the piston having ring grooves therearound with metal piston rings therein, the improvement of at least one of said grooves having a plastic piston ring received therein positioned radially interiorly of the metal piston ring, said plastic piston ring being resilient and having a pressure-receiving axial groove therein, the plastic piston ring being responsive to the presence of pressures in said ring groove radially behind the said metal ring by sealing contact between the plastic piston ring and the backwall of the ring groove and inner diameter of the metal ring.

Claim 18

In an internal combustion engine having at least one piston reciprocatingly positioned in a cylinder, the piston having ring grooves therearound with metal piston rings therein, the improvement of at least one of said grooves having a plastic piston ring received therein positioned radially interiorly of the metal piston ring, said plastic piston ring being resilient and having a pressure-receiving axial groove therein, the plastic piston ring being responsive to the presence of pressures in said ring groove radially behind the said metal ring by sealing contact between the plastic piston ring and the backwall of the ring groove and inner diameter of the metal ring.