Turbocharger housing, turbocharger and a multi-turbocharger boosting system

1. A turbocharger housing comprising a main body that bears a shaft that carries a turbine wheel and a compressor wheel, a seal portion that seals a clearance between the shaft and the turbocharger housing, the seal portion disposed axially between a main body space and a compressor wheel space, and an O-ring,

characterized in that

said seal portion is formed by an insert fitted to the main body, wherein said insert comprises a passage that supplies a fluid to said seal portion

wherein said passage comprises a partial bore that intersects a through bore,

wherein said partial bore comprises an open end that faces said main body, and

wherein said through bore comprises an open end at an inner circumference of said insert and a sealable end at an outer circumference of said insert that faces a radial surface of said main body

wherein said insert comprises an annular groove along said outer circumference of said insert, said O-ring seated in said annular groove and making direct contact with said sealable end of said through bore thereby sealing said sealable end of said through bore.

2. A turbocharger housing according to claim 1 , wherein said seal portion formed by said insert is opposed to a seal bushing provided on the shaft, wherein said seal bushing supports a first piston ring, and said passage supplies the fluid to one side of said first piston ring.

3. A turbocharger housing according to claim 2 , wherein said seal bushing supports a second piston ring and said passage supplies the fluid to a space formed between said first and second piston rings.

4. A turbocharger housing according to any one of claims 1 to 3 , wherein said through bore comprises a radial bore and wherein said partial bore comprises an axial bore.

5. A turbocharger housing according to claim 1 , wherein the insert comprises, on a plane surface thereof which faces the main body, protrusions for passing screws therethrough for fixing the insert to the main body.

6. A turbocharger housing according to claim 1 , wherein said insert forms a backplate for the compressor wheel.

7. A turbocharger housing according to claim 1 , wherein said insert is a ring-shaped member, the inner circumference of which forms said seal portion.

8. A turbocharger housing according to claim 1 , wherein said open end of said partial bore comprises an inlet opening which communicates with an outlet opening of another passage formed in the main body.

9. A turbocharger comprising a turbocharger housing according to claim 1 .

10. A turbocharger according to claim 9 , wherein the passage communicates with air outside the turbocharger.

11. A turbocharger according to claim 9 , wherein the passage communicates with a compressor output and/or a turbine input of the turbocharger.

12. A turbocharger according to claim 9 , wherein said passage communicates with a space where said turbine wheel or said compressor wheel of the turbocharger is located.

13. A multi-turbocharger boosting system comprising at least a first turbocharger and a second turbocharger, wherein at least the first turbocharger is a turbocharger according to claim 9 , wherein the passage thereof communicates with a compressor output and/or a turbine input of said second turbocharger.

14. A multi-turbocharger boosting system according to claim 13 , wherein the first turbocharger and the second turbocharger are connected in parallel.

15. A turbocharger according to claim 1 wherein said sealable end of said through bore comprises threads.

16. A turbocharger according to claim 1 wherein, said passage provides pressurized fluid that reduces leakage of shaft lubricant from said main body space to said compressor wheel space.