Exhaust gas turbocharger with plain bearing for reducing fluid turbulence

Abstract

An exhaust-gas turbocharger may include a rotor shaft arranged with at least one bearing-shaft portion in a radial bearing. The radial bearing may be a plain bearing configured to slide on a fluid film. The at least one bearing-shaft portion may be subdivided into two outer segments by an inner segment. The two outer segments may be arranged on the respective axial end region of the radial bearing and the inner segment may be positioned between the outer segments. The inner segment may be arranged in the area of an opening of a fluid channel. The turbocharger may include at least one transverse groove running inclined relative to the circumferential direction of the rotor shaft arranged in at least in one of the outer segments. The at least one transverse groove may include a groove depth having a continuously decreasing development in a fluid flow direction.

1 . An exhaust-gas turbocharger comprising: a rotor shaft being arranged with at least one bearing-shaft portion in a radical bearing, the radial bearing being a plain bearing being rotationally moveable and configured to slide on a fluid film, wherein
 the at least one bearing-shaft portion is subdivided into two outer segments by an inner segment, the two outer segments arranged on the respective axial end region of the radial bearing and the inner segment positioned between the outer segments,   further wherein the inner segment is arranged in the area of an opening of a fluid channel of the radial bearing, and   at least one transverse groove running inclined relative to the circumferential direction of the rotor shaft arranged in at least in one of the outer segments, wherein the at least one transverse groove includes a groove depth including a continuously decreasing development in a fluid flow direction.   
     
     
         2 . The exhaust-gas turbocharger according to  claim 1 , wherein the at least one transverse groove runs along a direction of rotation of the rotor shaft from the respective outer segment to the inner segment and the fluid flow direction runs from the inner segment to the outer segments. 
     
     
         3 . The exhaust-gas turbocharger according to  claim 1 , wherein the at least one transverse groove is arranged at a predetermined angle β relative to a longitudinal direction of the rotor shaft. 
     
     
         4 . The exhaust-gas turbocharger according to  claim 1 , wherein the at least one transverse groove protrudes into the inner segment. 
     
     
         5 . The exhaust-gas turbocharger according to  claim 1 , wherein a spacing between a rotor shaft-rotation axis and a transverse groove-free inner segment-surface region is equal to a spacing between the rotor shaft-rotation axis and a transverse groove-free outer segment-surface region. 
     
     
         6 . The exhaust-gas turbocharger according to  claim 1 , wherein a spacing between a rotor shaft-rotation axis and a transverse groove-free inner segment-surface region is smaller than a spacing between a rotor shaft-rotation axis and a transverse groove-free outer segment-surface region. 
     
     
         7 . The exhaust-gas turbocharger according to  claim 1 , wherein a spacing between a rotor shaft-rotation axis and a transverse groove-free inner segment-surface region is equal to a spacing between a rotor shaft-rotation axis and a deepest point of the at least one transverse groove in a connecting region of the at least one transverse groove to the inner segment. 
     
     
         8 . The exhaust-gas turbocharger according to  claim 1 , wherein a groove depth of the at least one transverse groove decreases along a fluid flow direction within the at least one transverse groove. 
     
     
         9 . The exhaust-gas turbocharger according to  claim 1 , wherein the at least one transverse groove includes groove edges having at least one of rounding, a chamfer or a broken edge. 
     
     
         10 . The exhaust-gas turbocharger according to  claim 1 , wherein a cross section of the at least one transverse groove is at least one of rectangular, at least partially ellipsoid, and at least partially half-round. 
     
     
         11 . The exhaust-gas turbocharger according to  claim 1 , wherein the at least one transverse groove runs along a direction of rotation from the inner segment to the respective outer segment and a fluid flow direction runs from the outer segments to the inner segment. 
     
     
         12 . The exhaust-gas turbocharger according to  claim 1 , wherein the at least one transverse groove includes at least two transverse grooves, the two transverse grooves being interconnected in the inner segment. 
     
     
         13 . The exhaust-gas turbocharger according to  claim 2 , wherein the at least one such transverse groove is arranged at a predetermined angle β relative to a longitudinal direction of the rotor shaft. 
     
     
         14 . The exhaust-gas turbocharger according to  claim 13 , wherein the at least one transverse groove protrudes into the inner segment. 
     
     
         15 . The exhaust-gas turbocharger according to  claim 14 , wherein a spacing between a rotor shaft-rotation axis and a transverse groove-free inner segment-surface region is equal to a spacing between the rotor shaft-rotation axis and a transverse groove-free outer segment-surface region. 
     
     
         16 . The exhaust-gas turbocharger according to  claim 14 , wherein a spacing between a rotor shaft-rotation axis and a transverse groove-free inner segment-surface region is smaller than a spacing between a rotor shaft-rotation axis and a transverse groove-free outer segment-surface region. 
     
     
         17 . The exhaust-gas turbocharger according to  claim 14 , wherein a spacing between a rotor shaft-rotation axis and a transverse groove-free inner segment-surface region is equal to a spacing between a rotor shaft-rotation axis and a deepest point of the at least one transverse groove in a connecting region of the at least one transverse groove to the inner segment. 
     
     
         18 . The exhaust-gas turbocharger according to  claim 17 , wherein a groove depth of the at least one transverse groove decreases along a fluid flow direction within the at least one transverse groove. 
     
     
         19 . The exhaust-gas turbocharger according to  claim 18 , wherein the at least one transverse groove includes groove edges having at least one of a rounding, a chamfer or a broken edge. 
     
     
         20 . The exhaust-gas turbocharger according to  claim 19 , wherein a cross section of the at least one transverse groove is at least one of rectangular, at least partially ellipsoid, and at least partially half-round.