Helical inner diameter groove journal bearing

1. A bearing assembly for a turbocharger comprising:

a turbine side journal bearing, semi- or fully floating, that comprises helical grooves along an inner journal surface wherein each helical groove comprises a lubricant opening, a well that spans the opening and opposing arms offset from the opening and extending from the well wherein each arm terminates at a respective axial surface of the journal bearing and wherein well depth exceeds arm depth of each arm where each arm terminates;

a compressor side journal bearing, semi- or fully floating, that comprises helical grooves along an inner journal surface wherein each helical groove comprises a lubricant opening, a well that spans the opening and opposing arms offset from the opening and extending from the well wherein each arm terminates at a respective axial surface of the journal bearing and wherein well depth exceeds arm depth of each arm where each arm terminates; and

a spacer to space the turbine side journal bearing and the compressor side journal bearing along an axis.

2. The bearing assembly of claim 1 wherein each helical groove comprises a groove span defined by an azimuthal angle about the axis.

3. The bearing assembly of claim 2 wherein the groove span comprises a well span and arm spans.

4. The bearing assembly of claim 3 wherein the well span exceeds the sum of the arm spans.

5. The bearing assembly of claim 1 wherein each of the opposing arms comprises an arm span defined as an azimuthal angle about the axis.

6. The bearing assembly of claim 1 wherein each groove comprises cross-sections, orthogonal to the axis, defined by one or more radii.

7. The bearing assembly of claim 1 wherein each arm comprises a cross-section, orthogonal to the axis, defined by a radius.

8. The bearing assembly of claim 1 wherein each journal bearing comprises three grooves.

9. The bearing assembly of claim 1 wherein each journal bearing comprises four grooves.

10. The bearing assembly of claim 1 wherein each groove comprises symmetrical arms, symmetric by rotation of 180 degrees about an axis of a respective lubricant opening.

11. The bearing assembly of claim 1 wherein each bearing comprises a symmetrical bearing.

12. The bearing assembly of claim 1 wherein each bearing comprises one or more axial recesses.

13. The bearing assembly of claim 1 wherein each bearing comprises one or more outer surface grooves configured to provide for flow of lubricant to or from one or more of the openings.

14. The bearing assembly of claim 1 wherein each of the journal bearings comprise a surface or surfaces disposed at an inner diameter of the journal bearing that supports a turbocharger shaft regardless of angular orientation of the journal bearing in a bore of a housing.

15. The bearing assembly of claim 1 wherein the turbine side journal bearing and the spacer comprise a unitary piece or the compressor side journal bearing and the spacer comprise a unitary piece.

16. A unitary semi- or fully floating bearing for a turbocharger comprising:

a turbine side journal bearing section that comprises helical grooves along an inner journal surface wherein each helical groove comprises a lubricant opening, a well that spans the opening and opposing arms offset from the opening and extending from the well wherein each arm terminates at a respective axial surface of the journal bearing section and wherein well depth exceeds arm depth of each arm where each arm terminates;

a compressor side journal bearing section that comprises helical grooves along an inner journal surface wherein each helical groove comprises a lubricant opening, a well that spans the opening and opposing arms offset from the opening and extending from the well wherein each arm terminates at a respective axial surface of the journal bearing section and wherein well depth exceeds arm depth of each arm where each arm terminates; and

a spacer section disposed between the turbine side journal bearing section and the compressor side journal bearing section.