Dual volute turbocharger with asymmetric tongue-to-wheel spacing
The present invention is related to the housing ( 60 ) of an exhaust turbine ( 32 ) of a turbocharger comprising a first volute ( 61 ) and a second volute ( 62 ), each of the volutes ( 61,62 ) ending in respective first and second guide tongues ( 64,66 ). The gap between the first guide tongue ( 64 ) and turbine wheel is smaller than the gap between the second guide tongue ( 66 ) and turbine wheel. This tongue asymmetry allows for control of the pulse amplitude emitted when a blade of the turbine wheel passes by each respective tongue. Moreover, by increasing the wheel-to-tongue distance of only the second guide tongue ( 66 ) durability requirements can be met.
1. A turbocharger turbine housing ( 60 ) in a form of a spiral casing having at least first and second volutes ( 61 , 62 ) defining separate flow paths to a turbine wheel bore ( 63 ), the turbine wheel bore ( 63 ) adapted to receive a turbine wheel ( 1 ) having a turbine wheel circumference ( 2 ), the flow paths ending with a first and a second guide tongue, respectively ( 64 , 66 ), wherein a gap between the first guide tongue ( 64 ) and the turbine wheel ( 1 ) circumference ( 2 ) is smaller than a gap between the second guide tongue ( 66 ) and the turbine wheel circumference ( 2 ), wherein a tongue-to-gap ratio (TGR) of the second guide tongue ( 66 ), measured as wheel-to-tongue gap at the closest point divided by the wheel diameter, is fixed from the range of 0.15-0.04, a TGR of the first guide tongue ( 64 ) is fixed in the range of 0.08-0.01, and a ratio of the larger TGR to the smaller TGR is fixed from the range of 1.5 to 4.
2. The turbocharger turbine housing as claimed in claim 1 , wherein the TGR of the second guide tongue ( 66 ) is fixed from the range of 0.1-0.05.
3. The turbocharger turbine housing as claimed in claim 1 , wherein the TGR of the second guide tongue ( 66 ) is fixed from the range of 0.08-0.05.
4. The turbocharger turbine housing as claimed in claim 1 , wherein the TGR of the second guide tongue ( 66 ) is fixed from the range of 0.07-0.06.
5. The turbocharger turbine housing as claimed in claim 1 , wherein the TGR of the first guide tongue ( 66 ) is fixed from the range of 0.07-0.02.
6. The turbocharger turbine housing as claimed in claim 1 , wherein the TGR of the first guide tongue ( 66 ) is fixed from the range of 0.06-0.03.
7. The turbocharger turbine housing as claimed in claim 1 , wherein the TGR of the first guide tongue ( 66 ) is fixed in the range of 0.05-0.04.
8. The turbocharger turbine housing as claimed in claim 1 , wherein the ratio of the larger TGR to the smaller TGR is fixed from the range of 2-3.
9. A cast turbocharger turbine housing ( 60 ) in a form of a spiral casing having at least first and second volutes ( 61 , 62 ) defining separate flow paths to a turbine wheel bore ( 63 ), the turbine wheel bore ( 63 ) adapted to receive a turbine wheel ( 1 ) having a turbine wheel circumference ( 2 ), the flow paths ending with a first and a second guide tongue, respectively ( 64 , 66 ), wherein a gap between the first guide tongue ( 64 ) and the turbine wheel ( 1 ) circumference ( 2 ) has a first wheel-to-tongue distance (D 1 ), a gap between the second guide tongue ( 66 ) and the turbine wheel circumference ( 2 ) has a second wheel-to-tongue distance (D 2 ), wherein the first wheel-to-tongue distance (D 1 ) is smaller than the second wheel-to-tongue distance (D 2 ), and wherein the first wheel-to-tongue distance (D 1 ) and the second wheel-to-tongue distance (D 2 ) are produced by casting or by machining of the cast turbine housing.
10. The turbocharger turbine housing as claimed in claim 9 , wherein the first and second volutes are asymmetric.
11. The turbocharger turbine housing as claimed in claim 10 , wherein one of the at least first and second volutes is connected to an exhaust gas recirculation line.
12. The turbocharger turbine housing as claimed in claim 9 , wherein the turbine housing houses a variable geometry turbine.
13. The turbocharger turbine housing as claimed in claim 9 , wherein said first and second guide tongues ( 64 , 66 ) have tips, and wherein the first guide tongue tip is offset 180° circumferentially from the second guide tongue tip.
14. The turbocharger turbine housing as claimed in claim 9 , wherein the first and second guide tongues ( 64 , 66 ) have tips, and wherein the first guide tongue tip is offset 165°-177° circumferentially from the second guide tongue tip.