SURFACE TREATED COMPRESSION RING AND METHOD OF MANUFACTURE
A piston ring is provided having a first axially facing surface and a second axially facing surface. At least one of the first and second axially facing surfaces has a friction reducing surface treatment. The friction reducing surface treatment is preferably formed from tungsten disulfide. Additionally, a method of forming a low friction piston ring is provided including applying a friction reducing surface treatment, such as tungsten disulfide, to at least one of the first and second axially facing surfaces and preventing the application of the friction reducing surface treatment on the radially outwardly facing surface. An internal combustion engine incorporating the disclosed piston ring is also provided.
1 . A piston ring adapted to be received within a groove defined by a piston, the piston ring comprising:
a first axially facing surface;
a second axially facing surface;
a generally radially outwardly facing surface;
wherein at least one of said first and second axially facing surfaces has a friction reducing surface treatment provided thereon; and
wherein said piston ring is further characterized by the lack of said friction reducing surface treatment on said generally radially outwardly facing surface.
2 . The piston ring of claim 1 , wherein the friction reducing surface treatment is formed from tungsten disulfide.
3 . The piston ring of claim 1 , wherein said piston ring is a first compression ring.
4 . The piston ring of claim 1 , wherein said piston ring is a second compression ring.
5 . The piston assembly of claim 1 , wherein said piston ring is formed from iron.
6 . The piston ring of claim 1 , wherein said piston ring is formed from steel.
7 . An internal combustion engine comprising:
a cylinder block defining a cylinder bore;
a piston reciprocally movable within said cylinder bore;
wherein said piston defines at least one generally annular ring groove;
a piston ring having a first axially facing surface and a second axially facing surface;
wherein said at least one generally annular ring groove is sufficiently configured to receive at least a portion of said piston ring; and
wherein at least one of said first and second axially facing surfaces has a friction reducing surface treatment provided thereon.
7 . The internal combustion engine of claim 6 , wherein said friction reducing surface treatment is formed from tungsten disulfide.
8 . The internal combustion engine of claim 6 , wherein said piston ring is a first compression ring.
9 . The internal combustion engine of claim 6 , wherein said piston ring is a second compression ring.
10 . The internal combustion engine of claim 6 , wherein said piston ring is formed from iron.
11 . The internal combustion engine of claim 6 , wherein said piston ring is formed from steel.
12 . The internal combustion engine of claim 6 , wherein said piston ring has a generally radially outwardly facing surface in contact with said cylinder and wherein said piston ring is further characterized by the lack of said friction reducing surface treatment on said generally radially outwardly facing surface.
13 . A method of forming a low friction piston ring having first and second axially facing surfaces and a radially outwardly facing surface, the method comprising:
applying a friction reducing surface treatment to at least one of the first and second axially facing surfaces; and
substantially preventing the application of said friction reducing surface treatment from contacting the radially outwardly facing surface.
13 . The method of claim 12 , wherein said friction reducing surface treatment is applied by burnishing.
14 . The method of claim 12 , wherein said friction reducing surface treatment is applied by spray impingement.
15 . The method of claim 12 , wherein the piston ring is formed from one of steel and iron.
16 . The method of claim 12 , wherein said friction reducing surface treatment is formed from tungsten disulfide.