US 11,408,508 C1 (13,118th)
Piston ring
Walter Stumpf, Essen (DE); Steffen Hoppe, Overath (DE); Ralf Lammers, Wermelskirchen (DE); and Rudolf Linde, Wermelskirchen (DE)
Filed by FEDERAL-MOGUL BURSCHEID GMBH, Burscheid (DE)
Assigned to FEDERAL-MOGUL BURSCHEID GMBH, Burscheid (DE)
Reexamination Request No. 90/019,687, Sep. 30, 2024.
Reexamination Certificate for Patent 11,408,508, issued Aug. 9, 2022, Appl. No. 16/768,572, May 29, 2020.
PCT Filed Nov. 28, 2018, PCT No. PCT/EP2018/082789
§ 371(c)(1), (2) Date May 29, 2020,
PCT Pub. No. WO2019/105979, PCT Pub. Date Jun. 6, 2019.
Ex Parte Reexamination Certificate issued on Dec. 16, 2025.
Int. Cl. F16J 9/26 (2006.01); C23C 14/06 (2006.01); C23C 28/00 (2006.01); F02F 5/00 (2006.01)
CPC F16J 9/26 (2013.01) [C23C 14/0605 (2013.01); C23C 28/322 (2013.01); C23C 28/343 (2013.01); C23C 28/347 (2013.01); F02F 5/00 (2013.01)]
OG exemplary drawing
AS A RESULT OF REEXAMINATION, IT HAS BEEN DETERMINED THAT:
The patentability of claim 18 is confirmed.
Claims 1-12 and 14 are determined to be patentable as amended.
Claims 13 and 15-17, dependent on an amended claim, are determined to be patentable.
New claims 19-24 are added and determined to be patentable.
1. A piston ring (10) having at least one running surface (12) and flank surfaces (14) which are coated, wherein an uppermost layer of [ a coating on ] the running surface (12) is a hydrogen-containing or hydrogen-free DLC layer and an uppermost layer of [ a coating on ] at least one of the flank surfaces (14) is a chromium layer [ formed by a galvanic process, and wherein a chromium layer formed by a galvanic process is not disposed below the DLC layer on the running surface] .
2. The piston ring (10) according to claim 1, wherein the DLC layer is hydrogen-free.
3. The piston ring (10) according to claim 1 including a chromium layer at least in some areas below the DLC layer.
4. The [ A ] piston ring (10) according to claim 3 [ having a running surface and a flank surface, the piston ring including a coating on the running surface and the flank surface, wherein an uppermost layer of the coating on the running surface is a DLC layer and an uppermost layer of the coating on the flank surface is a chromium layer] , wherein the DLC layer at least partially overlaps the chromium layer [ only ] in the [ an ] area of the peripheral edges [ of the running surface and the flank surface, and a chromium layer formed by a galvanic process is not disposed below the DLC layer on the running surface beyond the area of the peripheral edges.]
5. The piston ring (10) according to claim 1, wherein the DLC layer is formed by a PVD process.
6. The piston ring (10) according to claim 1, wherein the chromium layer has a hardness of at least 800 HV 0.1.
7. The piston ring (10) according to claim 1, wherein the chromium layer has a crack density with a crack rate of 700 to 1200 cracks/cm.
8. The piston ring (10) according to claim 1, wherein in lubricated friction contact, a friction coefficient of the chromium layer is at least 20% lower than that of nitrided chromium steel.
9. The piston ring (10) according to claim 1 [ 4] , wherein the chromium layer [ disposed on the flank surface ] is galvanically formed.
10. The piston ring (10) according to claim 1, wherein the flank surface (14) has a roughness of less than Rz 4.
11. The piston ring (10) according to claim 1, wherein the chromium layer has particle deposits.
12. A method for producing a piston ring (10), in which [ having a running surface, at least one flank surface, and a transition area at peripheral edges of the running surface and the at least one flank surface, comprising:
forming a chromium layer as an uppermost layer of the at least one flank surface;
forming ] a DLC layer is formed as the uppermost layer of a [ the ] running surface (12) of the piston ring , and a chromium layer is formed as the uppermost layer of at least one flank surface (14) of the piston ring [ such that the DLC layer overlaps the chromium layer in the transition area;
and wherein a chromium layer formed by a galvanic process is not formed below the DLC layer on the running surface beyond the transition area] .
14. The method according to claim 12 wherein the [ including forming a ] chromium layer is galvanically formed [ below the DLC layer on the running surface] .
[ 19. The piston ring according to claim 18, wherein the DLC layer is hydrogen-free.]
[ 20. The piston ring according to claim 18, wherein the chromium layer is formed by a galvanic process and is not disposed below the DLC layer.]
[ 21. The piston ring according to claim 1 including a transition surface between the running surface and one of the flank surfaces, wherein the transition surface is beveled.]
[ 22. The piston ring according to claim 1, wherein the DLC layer is hydrogen-free; the DLC layer is formed by a PVD process; the chromium layer formed by the galvanic process has a hardness of at least 800 HV 0.1; the chromium layer has a crack density with a crack rate of 700 to 1200 cracks/cm; wherein in lubricated friction contact, a friction coefficient of the chromium layer formed by the galvanic process is at least 20% lower than that of nitrided chromium steel.]
[ 23. The piston ring according to claim 4, wherein the DLC layer is hydrogen-free.]
[ 24. The piston ring according to claim 4 including a transition surface between the running surface and one of the flank surfaces, wherein the transition surface is beveled.]