Supercharger

1. A supercharger, comprising:

a housing having a cooling water jacket provided therein; and

a turbine shaft supported in a center hole in a center portion of the housing through a rolling bearing, a turbine being mounted on one end portion of the turbine shaft and disposed exteriorly of the housing in an axial direction,

wherein lubricating oil for the rolling bearing exists only within the housing,

wherein the cooling water jacket is provided within a body portion of the housing over a region from one axial end portion of the body portion to an other axial end portion thereof, and

wherein the cooling water jacket comprises a portion within the body portion that is disposed between the turbine and an end portion of the rolling bearing that is closer to the turbine than other parts of the rolling bearing.

2. The supercharger according to claim 1 , wherein the cooling water jacket comprises a passage for flowing a coolant at least more than one round around the center hole in a circumferential direction.

3. The supercharger according to claim 2 , wherein the passage is constructed such that the coolant is flowed circumferentially in one direction, and then is turned back, and is flowed circumferentially in an other direction opposite to the one direction.

4. The supercharger according to claim 3 , wherein the passage includes at least one first passage portion for flowing the coolant in the one direction, at least one second passage portion for flowing the coolant in the other direction, and at least one turning-back passage portion interconnecting the first passage portion and the second passage portion, and the first passage portion and the second passage portion are juxtaposed in the axial direction.

5. The supercharger according to claim 1 , wherein the portion of the cooling water jacket is disposed on a surface of a portion of the center portion that has a diameter that is less than a diameter of a remaining portion of the center portion.

6. The supercharger according to claim 1 , further comprising a thermal shield member interposed between the turbine and the housing,

wherein an air chamber is interposed between the thermal shield member and the housing.

7. The supercharger according to claim 1 , further comprising a tank portion for storing the lubricating oil provided within the housing or in a vicinity of the body portion of the housing, and supply means for supplying the lubricating oil from the tank potion to the center hole.

8. The supercharger according to claim 7 , wherein the supply means comprises a blade member for producing an air flow within the center hole in accordance with a rotation of the turbine shaft to render a pressure within the center hole negative relative to a pressure within the tank portion, and a lubricant passage leading from the tank portion to the center hole, and the lubricating oil is drawn up from the tank portion by the negative pressure, and flows to the center hole via the lubricant passage.

9. The supercharger according to claim 7 , wherein the supply means includes a wick member provided between the tank portion and the center hole to supply the lubricating oil from the tank portion to the center hole by a capillary action of the wick member.

10. A supercharger, comprising:

a housing having a cooling water jacket provided therein; and

a turbine shaft supported in a center hole in a center portion of the housing through a rolling bearing, a turbine being mounted on one end portion of the turbine shaft and disposed exteriorly of the housing in an axial direction,

wherein the cooling water jacket comprises a passage for flowing a coolant at least more than one round around the center hole in a circumferential direction, and

wherein the cooling water jacket comprises a portion that is disposed between the turbine and an end portion of the rolling bearing that is closer to the turbine than other parts of the rolling bearing.

11. The supercharger according to claim 10 , wherein the passage is constructed such that the coolant is flowed circumferentially in one direction, and then is turned back, and is flowed circumferentially in an other direction opposite to the one direction.

12. The supercharger according to claim 11 , wherein the passage includes at least one first passage portion for flowing the coolant in the one direction, at least one second passage portion for flowing the coolant in the other direction, and at least one turning-back passage portion interconnecting the first passage portion and the second passage portion, and the first passage portion and the second passage portion are juxtaposed in the axial direction.

13. The supercharger according to claim 10 , wherein the portion of the cooling water jacket is disposed on a surface of a portion of the center portion that has a diameter that is less than a diameter of a remaining portion of the center portion.

14. The supercharger according to claim 10 further comprising a thermal shield member interposed between the turbine and the housing,

wherein an air chamber is interposed between the thermal shield member and the housing.

15. The supercharger according to claim 10 , further comprising a tank portion for storing the lubricating oil provided within the housing or in a vicinity of the body portion of the housing, and supply means for supplying the lubricating oil from the tank potion to the center hole.

16. The supercharger according to claim 15 , wherein the supply means comprises a blade member for producing an air flow within the center hole in accordance with a rotation of the turbine shaft to render a pressure within the center hole negative relative to a pressure within the tank portion, and a lubricant passage leading from the tank portion to the center hole, and the lubricating oil is drawn up from the tank portion by the negative pressure, and flows to the center hole via the lubricant passage.

17. The supercharger according to claim 15 , wherein the supply means includes a string member provided between the tank portion and the center hole to supply the lubricating oil from the tank portion to the center hole by a capillary action of the string member.

18. The supercharger according to claim 1 , wherein the cooling water jacket comprises a passage for flowing a coolant at least more than one round along the axial direction and around the center hole in a circumferential direction.

19. The supercharger according to claim 1 , wherein the cooling water jacket further comprises another portion within the body portion that has a diameter that is greater than a diameter of the portion of the cooling water jacket,

wherein the portion of the cooling water jacket comprises an annular portion.