Electrodynamically finished plain bearings
A method of electrodynamically finishing a plain bearing includes electrically separating a bearing housing from a journal shaft with a lubricant disposed on a bearing surface of the bearing housing. The bearing housing or the bearing housing is rotated relative to the other and a voltage differential applied across the bearing housing and the journal shaft. One or more asperities disposed on the bearing surface are eroded with electric discharge events between the journal shaft and the bearing housing. Electrodynamically finished bearing assemblies and reaction/momentum wheel arrangements having such bearing assemblies are also described.
1. A method of electrodynamically finishing a plain bearing assembly, comprising:
electrically separating a bearing housing from a journal shaft with a lubricant disposed on a bearing surface of the bearing housing;
rotating one of the bearing housing and the journal shaft relative to the other of the bearing housing and the journal shaft;
applying a voltage differential across the bearing housing and the journal shaft; and
eroding an asperity disposed on the bearing surface with an electric discharge event across a gap between the bearing housing and the journal shaft.
2. The method as recited in claim 1 , further comprising mechanically matching the journal shaft with the bearing housing prior to electrically separating the bearing housing and member.
3. The method as recited in claim 1 , further comprising communicating a mechanical load between the bearing housing and journal shaft through a lubricant film disposed in the gap.
4. The method as recited in claim 1 , further comprising reducing minimum mechanical separation between the bearing housing and the journal shaft.
5. The method as recited in claim 1 , further comprising rotating or sliding the journal shaft.
6. The method as recited in claim 1 , further comprising rotating the bearing housing.
7. The method as recited in claim 1 , further comprising smoothing the bearing surface by reducing an asperity disposed on the bearing surface.
8. The method as recited in claim 7 , wherein smoothing the bearing surface includes vaporizing a carbide asperity disposed on the bearing surface.
9. The method as recited in claim 7 , wherein smoothing the bearing surface includes vaporizing a metallic asperity disposed on the bearing surface.
10. The method as recited in claim 1 , wherein applying the voltage differential includes applying an alternating current voltage differential across bearing housing and journal shaft.
11. The method as recited in claim 1 , further comprising removing the voltage differential by comparison of one or more of a lubricant property, load, temperature, and rotational speed with a selected value.
12. A plain bearing assembly, comprising:
a bearing housing with a bearing surface; and
a journal shaft supported on the bearing surface with a lubricant disposed between the journal shaft and the bearing surface, wherein the bearing surface has an electrodynamically eroded surface portion finished to the journal shaft.
13. The plain bearing assembly as recited in claim 12 , wherein the plain bearing assembly includes a journal bearing or a thrust bearing.
14. The plain bearing assembly as recited in claim 12 , further comprising a lead electrically connected to the bearing housing.
15. The bearing assembly as recited in claim 12 , further comprising a lead electrically connected to the journal shaft.
16. The bearing assembly as recited in claim 12 , further comprising an alternative current (AC) source with a positive and a negative terminal, wherein the positive terminal is electrically connected to the journal shaft.
17. The bearing assembly as recited in claim 12 , further comprising a rotor fixed relative to the journal shaft; and a stator connected to the bearing housing.
18. The bearing assembly as recited in claim 17 , further comprising a mechanical rotation source operably connected to the rotor.
19. The bearing assembly as recited in claim 12 , wherein at least one of the bearing housing and the journal shaft comprises a carbide-containing metallic material.
20. A motor assembly, comprising:
a rotor; and
a bearing assembly as recited in claim 12 , wherein the bearing housing and the journal shaft include a carbide-containing metallic material,
wherein a minimum lubricant-film distance between the bearing surface and the journal is defined between an electrodynamically eroded asperity and the journal shaft.