Coated piston ring for an internal combustion engine

Patent metadata

Field	Value
Publication number	US-12578016-B2
Application number	US-202117318530-A
Country	US
Kind code	B2
Filing date	May 12, 2021
Priority date	May 12, 2021
Publication date	Mar 17, 2026
Grant date	Mar 17, 2026

Abstract

A coated piston ring for a piston is provided. The piston ring includes a running surface, a flank surface, and a transition surface therebetween. The transition surface curves or extends at an angle between the running surface and the flank surface. A running layer is disposed over the running surface and over at least a portion of the transition surface. A flank layer is disposed over the flank surface and over at least a portion of the transition surface. The running layer is applied by physical vapor deposition, and the running layer is applied by galvanic deposition. The running layer is formed of chromium nitride, and the flank layer is formed of chromium. A portion of the flank layer overlaps and is disposed outward of a portion of the running layer. During operation of the piston, the overlapping portion is spaced from both the piston and the cylinder.

First claim

What is claimed is:

1 . A piston ring, comprising:
a body portion surrounding a center axis, said body portion including a running surface, a flank surface, and a transition surface between said running surface and said flank surface, said transition surface extending inwardly toward said center axis and at an angle between said running surface and said flank surface, wherein said transition surface includes a convex portion proximate said running surface; a running layer disposed over said running surface and over at least a portion of said transition surface, said running layer being formed of chromium nitride; a flank layer disposed over said flank surface and over at least a portion of said transition surface, said flank layer being formed of chromium; and a portion of said flank layer which is disposed over said transition surface being disposed on a portion of said running layer.

2 . The piston ring of claim 1 , wherein said portion of said flank layer is disposed outward of said running layer.

3 . The piston ring of claim 1 , wherein said running layer is applied by physical vapor deposition.

4 . The piston of claim 1 , wherein said flank layer is applied by galvanic deposition.

5 . The piston of claim 1 , wherein said running layer and said flank layer provide outermost surfaces of said piston ring.

6 . The piston ring of claim 1 , wherein said body portion is formed of an iron-based material, said running surface is parallel to said center axis, and said flank surface is transverse to said center axis.

7 . The piston ring of claim 1 , wherein a majority of said transition surface extends at said angle and straight from said flank surface toward said running surface, said body portion includes a first sharp corner between said straight majority of said transition surface and said flank surface, and said convex portion extend s from said straight majority of said transition surface to said running surface.

8 . The piston ring of claim 7 , wherein said running layer is disposed on a portion of said transition surface, and said flank layer is disposed on a portion of said running layer and over an entirety of said transition surface.

9 . The piston ring of claim 1 , wherein a majority of said transition surface is disposed at said angle and straight between said flank surface and said running surface, said transition surface has a concave portion as it transitions from said straight majority of said transition surface toward said flank surface, said body portion includes a first sharp corner between said concave portion of said transition surface and said flank surface, said transition surface presents the convex portion as it transitions from said straight majority of said transition surface to said running surface.

10 . The piston ring of claim 9 , wherein said running layer is disposed on an entirety of said transition surface, said flank layer is disposed on a portion of said running layer and over a portion of said transition surface.

11 . The piston ring of claim 1 , wherein said running layer is disposed on an entirety of said transition surface, said flank layer is disposed on a portion of said running layer and over a portion of said transition surface.

12 . A piston assembly, comprising:
a piston including a ring groove; a piston ring disposed in said ring groove of said piston; said piston ring including a body portion surrounding a center axis, said body portion including a running surface facing away from said ring groove of said piston, a flank surface, and a transition surface between said running surface and said flank surface, said transition surface extending inwardly toward said center axis and at an angle between said running surface and said flank surface, wherein said transition surface includes a convex portion proximate said running surface; said piston ring including a running layer disposed over said running surface and over at least a portion of said transition surface, said running layer being formed of chromium nitride; said piston ring including a flank layer disposed over said flank surface and over at least a portion of said transition surface, said flank layer being formed of chromium; a portion of said flank layer which is disposed over said transition surface being disposed on a portion of said running layer; and said portion of said flank layer which is disposed on said running layer being spaced from said ring groove of said piston.

13 . The piston assembly of claim 12 , wherein said piston is disposed in a cylinder; and said portion of said flank layer which is disposed on said running layer is spaced from said cylinder.

14 . The piston assembly of claim 12 , wherein said portion of said flank layer which is disposed on said running layer is disposed outward of said running layer.

15 . The piston assembly of claim 12 , wherein said running layer and said flank layer provide outermost surfaces of said piston ring.

Assignees

• Fed Mogul Powertrain Llc

Inventors

• Dufek Daniel J
• Irrgeher Marc

Classifications

• Y10T428/12854

  Next to Co-, Fe-, or Ni-base component · CPC title

• F16J9/12

  Details · CPC title

• C25D3/04

  of chromium · CPC title

• C23C28/34

  including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates · CPC title

• C23C14/0641

  Nitrides (C23C14/0617 takes precedence) · CPC title