Fluid film conical or hemispherical floating ring bearings
A turbocharger is provided with an improved bearing which is formed as a floating ring bearing or a semi-floating ring bearing having a conical or hemispherical shape which supports both journal and thrust loads. The floating ring bearing may have conical floating ring bearings ( 70 ), ( 100 ), ( 180 ) that define inner and outer conical bearing surfaces ( 71 ), ( 108 ), ( 185 ) and ( 72 ), ( 109 ), ( 186 ) which cooperate on the inside with corresponding conical journals ( 75/76 ), ( 111/112 ), ( 187/188 ) that rotate with the shaft ( 53 ), and cooperate on the outside with a stationary bearing housing ( 52 ) to form inner and outer fluid films. Alternatively, the floating ring bearing may have a pair of hemispherical floating ring bearings ( 85 ), ( 140 ), ( 210 ) that have hemispherical inner and outer bearing surfaces ( 86 ), ( 144 ), ( 211 ) and ( 87 ), ( 145 ), ( 212 ) which form inner and outer fluid films. A semi-floating ring bearing may also be provided with these structures.
1. A floating ring bearing unit ( 51 ) for a turbocharger shaft ( 53 ), comprising: at least one annular ring bearing ( 70 ), ( 85 ) formed as one of a floating ring bearing which comprises a plurality of inner bearing surfaces ( 71 ), ( 86 ) and outer bearing surfaces ( 72 ), ( 87 ), said inner bearing surfaces ( 71 ), ( 86 ) and outer bearing surfaces ( 72 ), ( 87 ) each having one of a conical or hemispherical shape which extends transverse to a shaft axis ( 53 A) of the shaft ( 53 ), said outer bearing surfaces ( 72 ), ( 87 ) facing opposing chamber surfaces ( 59 ), ( 90 ) of a bearing housing ( 52 ) in spaced relation to allow formation of an outer fluid film therebetween during rotation of the shaft ( 53 ); annular first journals ( 75 ), ( 88 ) and annular second journals ( 76 ), ( 89 ) which surround the shaft ( 53 ) and respectively define journal surfaces ( 77 ), ( 92 ) and ( 78 ), ( 93 ) which face outwardly toward said inner bearing surfaces ( 71 ), ( 86 ) in spaced relation to allow formation of an inner fluid film therebetween during shaft rotation, said journal surfaces ( 77 ), ( 92 ) and ( 78 ), ( 93 ) each having one of a conical or hemispherical shape complementary to said shape of said inner bearing surfaces ( 71 ), ( 86 ); said inner bearing surfaces ( 71 ), ( 86 ) and outer bearing surfaces ( 72 ), ( 87 ) and said journal surfaces ( 77 ), ( 92 ) and ( 78 ), ( 93 ) being oriented complementary to each other at a respective transverse angle relative to said shaft axis ( 53 A) such that said inner and outer fluid films support axial thrust loads acting along the shaft ( 53 ) and radial loads oriented radially relative to the shaft ( 53 ).
2. The bearing unit according to claim 1 , wherein a plurality of said ring bearings ( 70 ), ( 85 ) are provided in axially spaced relation and each floats freely with said outer bearing surfaces ( 72 ), ( 87 ) facing radially outwardly in opposing relation with said chamber surfaces ( 59 ), ( 90 ).
3. The bearing unit according to claim 1 , wherein said ring bearing is formed as a semi-floating ring bearing ( 100 ), ( 140 ), ( 180 ), ( 210 ) having a plurality of said inner bearing surfaces ( 108 ), ( 144 ), ( 185 ), ( 211 ) and outer bearing surfaces ( 109 ), ( 145 ), ( 186 ), ( 212 ) provided in axially spaced relation and joined together by an intermediate wall ( 103 ), ( 141 ), ( 182 ), ( 218 ), said inner bearing surfaces ( 108 ), ( 144 ), ( 185 ), ( 211 ) facing inwardly toward journal surfaces ( 113 ), ( 114 ), ( 149 ), ( 150 ) of said annular journals ( 111 / 112 ), ( 147 / 148 ), ( 187 / 188 ) and ( 214 ).
4. The bearing unit according to claim 3 , wherein said wall ( 103 ), ( 141 ) comprises a lubricant feed passage ( 106 ), ( 142 ) extending radially through said wall ( 103 ), ( 141 ) and through which fluid is flowable between said outer and inner fluid films.
5. The bearing unit according to claim 4 , wherein said bearing housing ( 52 ) includes a feed port ( 102 ) feeding lubricating fluid to said feed passage ( 106 ), ( 142 ).
6. The bearing unit according to claim 3 , wherein said semi-floating ring bearing ( 180 ), ( 210 ) comprises a plurality of oil feed passages ( 191 ), ( 217 ) extending radially between said inner bearing surfaces ( 185 ), ( 211 ) and said outer bearing surfaces ( 186 ), ( 212 ) and through which lubricating fluid is flowable between said outer and inner fluid films.
7. The bearing unit according to claim 6 , wherein said outer bearing surfaces ( 186 ), ( 212 ) each includes an outer circumferential distribution groove ( 189 ), ( 215 ) which supplies lubricating fluid to said passages ( 191 ), ( 217 ).
8. The bearing unit according to claim 7 , wherein said bearing housing ( 52 ) includes a feed port ( 190 ), ( 216 ) feeding each of said grooves ( 189 ), ( 215 ) for feeding lubricating fluid to said feed passage ( 191 ), ( 217 ).
9. The bearing unit according to claim 1 , wherein an axial length of said journal surface ( 78 ), ( 93 ) on a turbine end of said bearing assembly is equal to or longer than an axial length of said journal surface ( 77 ), ( 92 ) on an opposite compressor end of said bearing unit.
10. The bearing unit according to claim 1 , wherein said ring bearings ( 100 ), ( 140 ), ( 180 ), ( 210 ) have a plurality of said inner bearing surfaces ( 108 ), ( 144 ), ( 185 ), ( 211 ) and said outer bearing surfaces ( 109 ), ( 145 ), ( 186 ), ( 212 ) provided in axially spaced relation, a plurality of lubricant feed passages ( 191 ), ( 217 ) being provided which extend radially between said inner bearing surfaces ( 185 ), ( 211 ) and said outer bearing surfaces ( 186 ), ( 212 ) and through which lubricating fluid is flowable between said outer and inner fluid films, said chamber surfaces ( 59 ) having lubricant feed ports ( 81 ), ( 190 ), ( 216 ) feeding fluid to said lubricant feed passages ( 191 ), ( 217 ) and said chamber surfaces ( 59 ) having a portion ( 261 ) of their circumference provided with an increased radius adjacent said oil feed ports ( 81 ), ( 190 ), ( 216 ) to define a recessed feed area which facilitates the flow of lubricating fluid to the outer fluid films.
11. The bearing unit according to claim 1 , wherein said ring bearings ( 100 ), ( 140 ), ( 180 ), ( 210 ) have a plurality of said inner bearing surfaces ( 108 ), ( 144 ), ( 185 ), ( 211 ) and said outer bearing surfaces ( 109 ), ( 145 ), ( 186 ), ( 212 ) provided in axially spaced relation, a plurality of lubricant feed passages ( 191 ), ( 217 ) being provided which extend radially between said inner bearing surfaces ( 185 ), ( 211 ) and said outer bearing surfaces ( 186 ), ( 212 ) and through which lubricating fluid is flowable between said outer and inner fluid films, said feed passages ( 191 ), ( 217 ) being skewed at an angle A relative to a radial direction ( 260 ) extending radially outwardly from said shaft axis ( 53 A).
12. The bearing unit according to claim 11 , wherein said feed passages ( 191 ), ( 217 ) are angled against the direction of shaft rotation to reduce a circumferential speed of the fluid flow in the inner films.
13. A turbocharger having a ring bearing unit ( 51 ) for a turbocharger shaft ( 53 ), comprising: at least one annular ring bearing ( 70 ), ( 85 ), ( 100 ), ( 140 ), ( 180 ), ( 210 ) formed as one of a floating ring bearing which comprises a plurality of outer bearing surfaces ( 72 ), ( 87 ), ( 109 ), ( 145 ), ( 186 ) and ( 212 ), said outer bearing surfaces ( 72 ), ( 87 ), ( 109 ), ( 145 ), ( 186 ) and ( 212 ) each having one of a conical or hemispherical shape which extends transverse to a shaft axis ( 53 A) of the shaft ( 53 ), said outer bearing surfaces ( 72 ), ( 87 ), ( 109 ), ( 145 ), ( 186 ) and ( 212 ) facing opposing chamber surfaces ( 59 ), ( 90 ) of a turbocharger housing ( 52 ) in spaced relation to allow formation of an outer fluid film therebetween during rotation of the shaft ( 53 ); and said outer bearing surfaces ( 72 ), ( 87 ), ( 109 ), ( 145 ), ( 186 ) and ( 212 ), and said chamber surfaces ( 59 ), ( 90 ) being oriented complementary to each other at a respective transverse angle relative to said shaft axis ( 53 A) such that said outer fluid films support axial thrust loads acting along the shaft ( 53 ) and journal loads oriented radially relative to the shaft ( 53 ).
14. The turbocharger according to claim 13 , wherein said ring bearing ( 100 ), ( 140 ), ( 180 ), ( 210 ) is formed as a semi-floating ring bearing wherein said outer bearing surfaces ( 109 ), ( 145 ), ( 186 ) and ( 212 ) are defined by pairs of axially adjacent rings ( 121 / 122 ), ( 161 / 162 ), ( 196 / 197 ), ( 221 / 222 ) wherein each said ring ( 121 / 122 ), ( 161 / 162 ), ( 196 / 197 ), ( 221 / 222 ) has one of a conical or hemispherical shape.
15. The turbocharger according to claim 14 , wherein each said ring ( 121 / 122 ), ( 161 / 162 ), ( 196 / 197 ), ( 221 / 222 ) includes circumferential grooves and passages supplying lubricant to an interior of said bearing ( 100 ), ( 140 ), ( 180 ), ( 210 ).