Sheet metal turbine housing

1. A sheet metal turbine housing mounted downstream of an engine exhaust manifold, comprising:

a spiral scroll part in which an exhaust gas flows so as to drive a turbine, the spiral scroll part including a first sheet metal scroll part having a first end surface extending in a thickness direction of a first sheet metal forming the first sheet metal scroll part and a second sheet metal scroll part having a second end surface opposing the first end surface and extending in a thickness direction of a second sheet metal forming the second sheet metal scroll part, and a penetration butt welded part that joins the first and second surfaces along an entire circumferential portion of the scroll spiral part; and

a center core part, substantially cylindrical in shape, and disposed in a volute center part of the spiral scroll part, the center core part includes:

a housing portion at one end which surrounds an outer circumference of a turbine wheel via a clearance and which forms a gas discharge port;

a bearing receiving portion at another end which is opposite to the one end and in which a bearing axially supporting a rotating shaft of the turbine wheel is fitted; and

a plurality of circumferentially spaced supports bridging a gap between the housing portion and the bearing receiving portion in an axial direction of the rotating shaft of the turbine wheel,

wherein the housing portion, the bearing receiving portion, and the plurality of circumferentially spaced supports are formed integrally in one piece from a steel pipe member in an annular shape by machining.

2. The sheet metal turbine housing according to claim 1 , wherein each of the plurality of circumferentially spaced supports have a cross-sectional shape, as viewed from the axial direction of the rotating shaft of the turbine wheel, with acute-angled corners both upstream and downstream of a flow of exhaust gas so that the plurality of circumferentially spaced supports have an upstream side face and a downstream side face inclined with respect to the flow of gas.

3. The sheet metal turbine housing according to claim 1 , wherein the housing portion surrounding the turbine wheel has a larger sheet thickness in a portion facing an outer circumference of the turbine wheel than in other portions.

4. The sheet metal turbine housing according to claim 3 , wherein the housing portion having the larger sheet thickness is at least a housing portion facing an outer circumference of the turbine wheel of the turbine.

5. The sheet metal turbine housing according to claim 1 , wherein each of the first sheet metal scroll part and the second sheet metal scroll part of the spiral scroll part has a double wall structure.

6. The sheet metal turbine housing according to claim 2 , wherein each of the first sheet metal scroll part and the second sheet metal scroll part of the spiral scroll part has a double wall structure.

7. The sheet metal turbine housing according to claim 3 , wherein each of the first sheet metal scroll part and the second sheet metal scroll part of the spiral scroll part has a double wall structure.

8. The sheet metal turbine housing according to claim 4 , wherein each of the first sheet metal scroll part and the second sheet metal scroll part of the spiral scroll part has a double wall structure.

9. The sheet metal turbine housing according to claim 1 , wherein each of the first sheet metal scroll part and the second sheet metal scroll part of the spiral scroll part has a sectional shape corresponding to the sectional shape of the spiral scroll part generally half split in the scroll direction.

10. The sheet metal turbine housing according to claim 9 , wherein each of the first sheet metal scroll part and the second sheet metal scroll part of the spiral scroll part has a double wall structure.