Piston ring configured to reduce friction

Patent metadata

Field	Value
Publication number	US-10077838-B2
Application number	US-201615207400-A
Country	US
Kind code	B2
Filing date	Jul 11, 2016
Priority date	Jul 10, 2015
Publication date	Sep 18, 2018
Grant date	Sep 18, 2018

Abstract

A piston ring for a piston, the piston ring having a circumferential surface configured to engage an inner surface of a cylinder, the inner surface having at least one recess indented into the inner surface, the engagement of the circumferential surface of the piston ring with the inner surface of the cylinder defining a contact zone therebetween, wherein the circumferential surface of the piston ring is configured such that the ratio of the dimension of the contact zone the direction of travel of the piston to the dimension of the recess in the direction of travel of the piston is in the range of approximately 5:1 to 5:3.

First claim

The invention claimed is:

1. A machine comprising a cylinder and a piston ring set for a piston of the machine, the piston ring set comprising a first piston ring having a first profile, in a direction of travel of the piston, and a second piston ring having a second profile, in the direction of travel of the piston, the first and second profiles being different, each of the piston rings having a circumferential surface configured to engage an inner surface of the cylinder of the machine, the inner surface having at least one recess indented into the inner surface, the engagement of a contact portion of the circumferential surface of each of the piston rings with the inner surface of the cylinder defining respective contact zones therebetween, a remainder of the circumferential surface of each piston ring not engaging the inner surface, wherein a film of lubricant is formed between the circumferential surface and the inner surface within the contact zone, wherein the circumferential surface of each of the piston rings is configured to deform elastically and be parallel to the inner surface of the cylinder upon engagement with and radial loading against the inner surface of the cylinder during operation of the machine, a dimension of the contact zone in the direction of travel of the piston being defined by a dimension of the elastically deformed portion of the circumferential surface in the direction of travel of the piston, and wherein the contact portion of the circumferential surface of each of the piston rings is configured such that a ratio of a dimension of each contact zone in the direction of travel of the piston to a dimension of the recess in the direction of travel of the piston is in a range of 5:1 to 5:3.

2. The machine according to claim 1 , wherein the inner surface has a plurality of recesses spaced apart from one another along the inner surface, in the direction of travel of the piston, each recess of the plurality of recesses having a dimension such that the ratio of the dimension of each contact zone in the direction of travel of the piston to the dimension of each recess in the direction of travel of the piston is in the range of 5:1 to 5:3.

3. The machine according to claim 1 , wherein the remainder of the circumferential surface of each piston ring not engaging the inner surface is a non-contacting portion configured to be spaced apart from the inner surface of the cylinder during operation of the machine.

4. The machine according to claim 1 , wherein the film of lubricant within the contact zone has a film thickness that is substantially constant in the direction of travel of the piston during operation of the machine.

5. The machine according to claim 4 , wherein the circumferential surface of each of the piston rings is configured to support the film of lubricant having a dimension in the direction of travel of the piston that is greater than the dimension of the recess in the direction of travel of the piston.

6. The machine according to claim 1 , wherein at least one of the piston rings comprises a plurality of the circumferential surfaces.

7. The machine according to claim 1 , wherein at least one of the piston rings is a compression ring, an oil scraper ring, or an oil control ring having a barreled, tapered, or contoured profile, respectively, in the direction of travel of the piston.

8. The machine according to claim 1 , wherein the first profile and the second profile are non-planar.

9. The machine according to claim 1 , wherein the dimension of the recess is 60+/−20 μm and the dimension of each contact zone is in a range of 100 to 300 μm.

10. The machine according to claim 9 , wherein the engagement between the contact portion of the circumferential surface of the first piston ring and the inner surface defines a first contact zone, wherein the engagement between the contact portion of the circumferential surface of the second piston ring and the inner surface defines a second contact zone, and wherein a ratio of the dimension of the recess in the direction of travel of the piston to a dimension of the first contact zone in the direction of travel of the piston is different to a ratio of the dimension of the recess in the direction of travel of the piston to a dimension of the second contact zone in the direction of travel of the piston.

11. The machine according to claim 10 , wherein a profile of at least one of the piston rings comprises at least one of a curved portion, a flat portion, and a tapered portion.

12. The machine according to claim 11 , wherein the circumferential surface comprises a plurality of projections.

Assignees

• Ford Global Tech Llc

Inventors

• Pegg Ian Graham

Classifications

• F16J9/062

  Coiled spring along the entire circumference · CPC title

• F16J9/12 Primary

  Details · CPC title

• F16J9/206

  One-piece oil-scraping rings · CPC title