# US 11,306,778 B2 · Sintered bearing for an EGR valve and manufacturing method thereof

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- Number: US 11,306,778 B2
- Document ID: US11306778B2
- Status: Granted
- Kind: B2
- Application number: 15/021,283
- Filed: 2014-09-11
- Published: 2016-08-04
- Granted: 2022-04-19
- Earliest claimed: 2013-09-13
- Assignees: Ntn Corporation
- Applicants: Ntn Corporation
- Inventors: Yoshinori Ito; Hiroharu Nagata; Tomoyuki Seto; Takahiro Gotou
- Web page: https://patentgrep.com/patent/US11306778B2

## CPC

- F16C 33/128: {Porous bearings, e.g. bushes of sintered alloy}
- B22F 1/09: {Mixtures of metallic powders}
- B22F 3/1003: {Use of special medium during sintering, e.g. sintering aid}
- B22F 3/16: in successive or repeated steps
- B22F 3/24: After-treatment of workpieces or articles {(B22F3/1146 takes precedence)}
- B22F 5/00: Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
- B22F 5/106: {Tube or ring forms}
- C22C 9/01: with aluminium as the next major constituent
- C22C 32/0084: {carbon or graphite as the main non-metallic constituent}
- F16C 33/121: {Use of special materials}
- F16C 33/145: {of sintered porous bearings}
- B22F 2998/10: Processes characterised by the sequence of their steps
- F16C 2204/10: Alloys based on copper
- F16C 2220/20: by sintering pulverised material, e.g. powder metallurgy
- F16C 2361/91: Valves
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

Provided is a sintered bearing for an EGR valve, including raw material powder including 9% by weight to 12% by weight of aluminum, 0.1% by weight to 0.6% by weight of phosphorus, 3% by weight to 10% by weight of graphite, and the balance including copper as a main component, and inevitable impurities. The sintered bearing has a structure of a sintered aluminum-copper alloy. The sintered bearing further includes free graphite distributed in pores formed so as to be dispersed.

## Claims

### Claim 1

A sintered bearing for an EGR valve, comprising,
9% by weight to 12% by weight of aluminum, 0.1% by weight to 0.6% by weight of phosphorus, 3% by weight to 10% by weight of graphite, and the balance comprising copper as a main component, and inevitable impurities, wherein:
the sintered bearing has a structure of a sintered aluminum-copper alloy,
the sintered bearing further comprises free graphite distributed in pores formed so as to be dispersed,
the sintered bearing does not contain tin,
a portion in which a copper simple substance is concentrated does not substantially exist in the sintered bearing,
the sintered bearing has a bearing surface on an inner circumference and a radially outer surface,
the sintered bearing has compressed layers on the radially outer surface and the bearing surface, respectively,
a density ratio αo of the compressed layer on the radially outer surface side is 80%≤αo≤95%, and a density ratio αb of the compression layer on the bearing surface side is 80%≤αb≤95%,
the density ratio αo of the compressed layer on the radially outer surface side and the density ratio αb of the compressed layer on the bearing surface side are both higher than a density ratio of an inside, and
when an average value of depths of the compressed layer on the radially outer surface side is defined as To, an average value of depths of the compressed layer on the bearing surface side is defined as Tb, and ratios of To and Tb to an inner diameter dimension D1 of the bearing surface are defined as To/D1 and Tb/D1, respectively, To/D1 are set to 1/100≤To/D1≤ 1/15 and Tb/D1 are set to 1/100≤Tb/D1≤ 1/15.

### Claim 2 (depends on 1)

The sintered bearing for an EGR valve according to claim 1, wherein the structure of the sintered aluminum-copper alloy comprises an α-phase.

### Claim 3 (depends on 1)

The sintered bearing for an EGR valve according to claim 1, wherein a ratio γ-phase/α-phase of a γ-phase and an α-phase of the structure of the sintered aluminum-copper alloy set to 0≤γ-phase/α-phase≤0.10.

### Claim 4 (depends on 2)

The sintered bearing for an EGR valve according to claim 2, wherein a ratio γ-phase/α-phase of a γ-phase and an α-phase of the structure of the sintered aluminum-copper alloy is set to 0≤γ-phase/α-phase≤0.10.