Internal-combustion engine piston ring, process for obtaining a piston ring, and internal-combustion engine

Patent metadata

Field	Value
Publication number	US-10407764-B2
Application number	US-201515517901-A
Country	US
Kind code	B2
Filing date	Oct 7, 2015
Priority date	Oct 9, 2014
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

A piston ring for an internal-combustion engine may include a body having a substantially annular external surface and a physical vapor deposition coating layer disposed on the external surface. The body may include a gap defined between a first end and a second end. The piston ring may also include a first half in a region of the gap and a second half opposite the first half. The coating layer of the first half may have a thickness gradient, and the coating layer may define a greater thickness in a vicinity of the first end and the second end and a reduced thickness in regions further away from the vicinity of the first end and the second end. The coating layer of the second half may have a uniform thickness.

First claim

The invention claimed is:

1. A piston ring for internal-combustion engines, comprising: a body having a substantially annular external surface and a physical vapor deposition coating layer disposed on the external surface, the body including a gap defined between a first end and a second end, such that in a planar view of the piston ring, an x-axis and y-axis pass through a center of the piston ring, the y-axis intersecting with a center of the gap, and the x-axis orthogonal to the y-axis and passing through the piston ring, a first half defined by a circumferential angle of the piston ring above the x-axis and including the gap and a second half defined by the piston ring below the x-axis, wherein the coating layer of the first half and toward the first end from one side and toward the second end from the other side has thickness gradients that increase to a maximum thickness and as the coating approaches regions approximate the gap from either side, and the coating reduces in thickness from the maximum thickness toward a vicinity of the gap on each of the first end and second end, and wherein the coating layer of the second half has a uniform thickness.

2. The piston ring as claimed in claim 1 , wherein the thickness gradient has a thickness of at least 15 microns and the maximum thickness of at least 55 microns.

3. The piston ring as claimed in claim 1 , wherein the coating layer of the first half in the vicinity of the gap on the first end and the second end is approximately 2% to 10% less thick than the coating layer of the maximum thickness.

4. The piston ring as claimed in claim 1 , wherein the coating layer of the first half in a region adjacent to the vicinity of the first end has a thickness of at least 55 microns and in a region adjacent to the vicinity of the second end has a thickness of at least 55 microns.

5. The piston ring as claimed in claim 1 , wherein the coating layer of the second half has the uniform thickness of at least 15 microns.

6. The piston ring as claimed in claim 1 , wherein the external surface is a sliding surface.

7. A method for coating an internal-combustion engine piston ring, comprising:
fastening at least one piston ring on a rotary table, the at least one piston ring including a gap positioned opposite at least one physical vapor deposition source of coating material;
performing a first rotation movement of the rotary table about a central axis while the at least one piston ring is stationary in relation to the rotary table, and receiving a first deposition of coating material on an external surface of the at least one piston ring in a region defined by a circumferential angle of 180° adjacent to a center of the gap by rotating the rotary table;
performing a relative rotation movement by performing the first rotation movement of the rotary table and performing a second rotation movement of the at least one piston ring relative to the rotary table such that the at least one physical vapor deposition source of coating material promotes a second deposition of coating material entirely along the external surface of the at least one piston ring; and
placing a physical barrier between the gap and the at least one source of coating material after at least one of performing the first rotation movement and performing the relative rotation movement;
wherein performing the first rotation movement and performing the relative rotation movement are alternated and wherein the first rotation movement and the second rotation movement are in opposite directions.

8. The method as claimed in claim 7 , wherein the first deposition of coating material forms substantially two thirds of a final thickness of a coating layer.

9. The method as claimed in claim 7 , wherein a coating material of the first deposition is different a coating material of the second deposition.

10. An internal-combustion engine, comprising: at least one piston ring including:
a body defining a substantially annular external surface and including a gap defined between a first end and a second end with a center of the gap defined as 0° and passing from 0° through 360°, the external surface having a first portion defined by a circumferential angle along the body of 180° that spans the center of the gap and extends from 270°, through 0°, to 90°, and a second portion defined by a circumferential angle along the body of from 90°, through 180°, and to 270° from the center of the gap;
a physical vapor deposition coating layer disposed on the external surface;
wherein the coating layer disposed on the first portion and toward the first end from one side and toward the second end from the other side has thickness gradients that increase to a maximum thickness and as the coating approaches regions approximate the gap from either side, and the coating reduces in thickness from the maximum thickness toward a vicinity of the gap on each of the first end and second end; and
wherein the coating layer disposed on the second portion has a uniform thickness.

11. The internal-combustion engine as claimed in claim 10 , wherein the coating layer has a thickness of at least 15 microns and the maximum thickness of at least 55 microns.

12. The internal-combustion engine as claimed in claim 10 , wherein the coating layer in the vicinity of the gap on the first end and the second end is approximately 2% to 10% less thick than the maximum thickness.

13. The internal-combustion engine as claimed in claim 10 , wherein the coating layer of the second portion has the uniform thickness of at least 15 microns.

14. The internal-combustion engine as claimed in claim 10 , wherein the external surface is a sliding surface.

15. The method as claimed in claim 7 , wherein performing the first rotation movement and receiving the first deposition of coating material is followed by performing the relative rotation movement.

16. The method as claimed in claim 7 , wherein the first rotation movement is one of the clockwise and counterclockwise, and the second rotation movement is the other of clockwise and counterclockwise.

17. The method as claimed in claim 7 , wherein receiving the first deposition of coating material includes forming a coating layer via physical vapor deposition on the external surface with a varying thickness that increases towards the gap.

18. The piston ring as claimed in claim 1 , wherein the coating layer disposed on the first half has a maximum thickness in a region of 10° and 350° from the center of the gap.

19. The piston ring as claimed in claim 18 , wherein the coating layer diminishes in thickness from a region of 10° and 350° towards the first end and the second end, respectively.

Assignees

• Mahle Int Gmbh
• Mahle Metal Leve Sa

Inventors

• Da Rocha Mordente Paulo Jose
• Da Silva Davi Antonio
• Costa Nuno

Classifications

• C23C14/044 Primary

  using masks to redistribute rather than totally prevent coating, e.g. producing thickness gradient · CPC title

• C23C14/22

  characterised by the process of coating · CPC title

• F16J15/12

  with metal reinforcement or covering · CPC title

• F16J9/26

  characterised by the use of particular materials · CPC title

• F16J9/14 Primary

  Joint-closures · CPC title