# US 10,245,806 B2 · Friction reduction for engine components

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- Number: US 10,245,806 B2
- Document ID: US10245806B2
- Status: Granted
- Kind: B2
- Application number: 14/000,857
- Filed: 2012-02-21
- Published: 2014-06-19
- Granted: 2019-04-02
- Earliest claimed: 2011-02-22
- Assignees: The George Washington University
- Applicants: Stephen M. Hsu; Yang Jing; Yufei Mo; Dongyun Hua; Ming Chen
- Inventors: Stephen M. Hsu; Yang Jing; Yufei Mo; Dongyun Hua; Ming Chen
- Web page: https://patentgrep.com/patent/US10245806B2

## CPC

- B32B 3/30: characterised by a layer formed with recesses or projections, e.g. {hollows, grooves, protuberances, ribs (apertured layer B32B3/266; layer with cavities or internal voids B32B3/26)}
- F16C 33/1075: {Wedges, e.g. ramps or lobes, for generating pressure}
- B05D 5/08: to obtain an anti-friction or anti-adhesive surface (rendering particulate materials free-flowing in general, e.g. making them hydrophobic B01J2/30)
- C23F 1/02: Local etching
- F02F 1/20: characterised by constructional features providing for lubrication
- F05C 2253/08: Crystalline
- F05C 2253/083: Directionally-solidified crystalline structure
- F16C 2360/22: Internal combustion engines
- Y10T 428/24355: Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
- Y10T 428/24851: Intermediate layer is discontinuous or differential
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02)
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F05C: INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The present invention relates to techniques for lowering friction between moving surfaces of, for example, an internal combustion engine. Friction reduction is achieved by adding texture modifications to surfaces that come in contact with each other. Texture modifications that reduce friction in accordance with the present invention include dimples of varying geometries and depths ion the surfaces of components. The present invention also relates to the fabrication technique for applying the textures to the surfaces. In another embodiment, the patterned soft mask is applied onto a large surface (flat or curved including cylindrical rollers surfaces) to be followed by electrochemical etching to imprint the textures onto the component. And, in another embodiment, a diamond-like-carbon (DLC) film may be applied to the turbine component to also reduce friction.

## Claims

### Claim 1

A surface texture of an engine component comprising:
a first set of identically shaped dimples arranged such as to form a first periodical pattern, wherein each dimple of the first set of dimples has a first geometry; and
a second set of identically shaped dimples arranged such as to form a second periodical pattern, wherein each dimple of the second set of dimples has a second geometry;
wherein the first periodical pattern is interlaced with the second periodical pattern so that each particular dimple in the first set of dimples is directly disposed between both two pairs of dimples in the first set of dimples immediately adjacent to the particular dimple in the first set of dimples and two pairs of dimples in the second set of dimples immediately adjacent to the particular dimple in the first set of dimples, and each particular dimple in the second set of dimples is also directly disposed between both two pairs of dimples in the first set of dimples immediately adjacent to the particular dimple in the second set of dimples and two pairs of dimples in the second set of dimples immediately adjacent to the particular dimple in the second set of dimples;
wherein the dimples having a second geometry have a smaller surface area than the dimples having a first geometry;
wherein the depth of the dimples of the first geometry is between one micron and five microns and the size of the dimples of the first geometry is between approximately thirty and three hundred microns in diameter, and
wherein the depth of the dimples of the second geometry is between five micron and twenty microns, and the size of the multiple dimples of the second geometry is between approximately ten and fifty microns in diameter.

### Claim 2 (depends on 1)

A surface texture according to claim 1, wherein the first set of identically shaped dimples are arranged to an areal density of 15 to 25% of a contact area.

### Claim 3 (depends on 2)

A surface texture according to claim 2, wherein the second set of identically shaped dimples are arranged to an areal density of 5 to 10% of the contact area.

### Claim 4 (depends on 3)

A surface according to claim 3, wherein friction of the engine component is reduced by 30-90%.

### Claim 5

A surface texture of an engine component comprising:
a first set of substantially identically shaped dimples arranged such as to form a first periodical pattern, wherein each dimple of the first set of dimples has a first geometry; and
a second set of identically shaped dimples arranged such as to form a second periodical pattern, wherein each dimple of the second set of dimples has a second geometry that is different from the first geometry;
wherein the first periodical pattern is interlaced with the second periodical pattern so that each particular dimple in the first set of dimples is directly disposed between both two pairs of dimples in the first set of dimples immediately adjacent to the particular dimple in the first set of dimples and two pairs of dimples in the second set of dimples immediately adjacent to the particular dimple in the first set of dimples, and each particular dimple in the second set of dimples is also directly disposed between both two pairs of dimples in the first set of dimples immediately adjacent to the particular dimple in the second set of dimples and two pairs of dimples in the second set of dimples immediately adjacent to the particular dimple in the second set of dimples;
wherein the dimples having a second geometry have a smaller surface area than the dimples having a first geometry;
wherein the size of dimples of the first geometry and the size of the dimples of the second geometry are between a few microns to hundreds of microns in diameter;
wherein the depth of the dimples of the first geometry is between one micron and eight microns; and
wherein the depth of the dimples of the second geometry is between one micron and eight microns.

### Claim 6 (depends on 5)

A surface texture according to claim 5, wherein the first set of identically shaped dimples are arranged to an areal density of 15 to 25% of a contact area.

### Claim 7 (depends on 6)

A surface texture according to claim 6, wherein the second set of identically shaped dimples are arranged to an areal density of 5 to 10% of the contact area.

### Claim 8 (depends on 7)

A surface according to claim 7, wherein friction of the engine component is reduced by 30-90%.

### Claim 9 (depends on 5)

A surface according to claim 5, wherein the first set of identically shaped dimples are located adjacent the second set of identically shaped dimples.

### Claim 10

A surface texture of an engine component comprising:
a first set of substantially identically shaped dimples arranged such as to form a first periodical pattern, wherein each dimple of the first set of dimples has a first geometry; and
a second set of identically shaped dimples arranged such as to form a second periodical pattern, wherein each dimple of the second set of dimples has a second geometry that is different from the first geometry;
wherein the first periodical pattern is interlaced with the second periodical pattern so that each particular dimple in the first set of dimples is directly disposed between both two pairs of dimples in the first set of dimples immediately adjacent to the particular dimple in the first set of dimples and two pairs of dimples in the second set of dimples immediately adjacent to the particular dimple in the first set of dimples, and each particular dimple in the second set of dimples is also directly disposed between both two pairs of dimples in the first set of dimples immediately adjacent to the particular dimple in the second set of dimples and two pairs of dimples in the second set of dimples immediately adjacent to the particular dimple in the second set of dimples;
wherein the dimples having a second geometry have a smaller surface area than the dimples having a first geometry;
wherein the size of dimples of the first geometry and the size of the dimples of the second geometry are between a few microns to hundreds of microns in diameter;
wherein the depth of the dimples of the first geometry is between one micron and eight microns;
wherein the depth of the dimples of the second geometry is between one micron and eight microns; and
wherein one of the first and second sets of identically shaped dimples is a set of circular dimples and the other of the first and second sets of identically shaped dimples is a set of elliptical dimples.