Compressor impeller assembly for a turbocharger

1. A compressor impeller assembly, comprising:

a compressor impeller having an impeller bore;

an insert screwed into the impeller bore, the insert having a threaded insert bore;

a shaft having a threaded shaft bore;

a stud, including:

a first threaded portion engaged with the threaded insert bore; and

a second threaded portion engaged with the threaded shaft bore, wherein the impeller bore is a first impeller bore having a first diameter and the compressor impeller includes:

a front end and a rear end opposite the front end;

a hub extension extending from the rear end to a first distal end between the front end and the rear end, the first impeller bore being disposed in the hub extension;

a second impeller bore having a second diameter, the second impeller bore extending from the front end to a second distal end disposed between the front end and the first distal end; and

a third impeller bore having a third diameter smaller than the first diameter and the second diameter, the third impeller bore extending from the first distal end to the second distal end.

2. The compressor impeller assembly of claim 1 , wherein

the stud extends from a first stud end to a second stud end,

the first threaded portion is disposed between the first stud end and the second stud end, and

the second threaded portion is disposed adjacent the second stud end.

3. The compressor impeller assembly of claim 2 , wherein

the threaded insert bore has first threads having a first pitch;

the threaded shaft bore has second threads having a second pitch different from the first pitch.

4. The compressor impeller assembly of claim 3 , wherein the second pitch is coarser than the first pitch.

5. The compressor impeller assembly of claim 1 , wherein the second impeller bore further includes:

a first annular recess disposed at a first axial distance from the front end;

a second annular recess disposed at a second axial distance from the front end, the second axial distance being larger than the first axial distance;

a first seal member is disposed in the first annular recess; and

a second seal member is disposed in the second annular recess.

6. The compressor impeller assembly of claim 5 , wherein the first annular recess has a first radius and the second annular recess has a second radius smaller than the first radius.

7. The compressor impeller assembly of claim 1 , wherein

the hub extension includes a first outer surface,

the insert includes:

a first insert portion disposed within the first impeller bore; and

a second insert portion disposed outside the first impeller bore, the second insert portion having a second outer surface, and

the compressor impeller assembly further includes an impeller cap, including:

a first cap bore that engages with the first outer surface; and

a second cap bore that engages with the second outer surface.

8. The compressor impeller assembly of claim 7 , wherein the second cap bore and the second outer surface include an anti-rotational feature.

9. The compressor impeller assembly of claim 8 , wherein the anti-rotational feature includes a three-lobed polygon.

10. A compressor impeller assembly, comprising:

a compressor impeller including:

a front end and a rear end opposite the front end;

a nose disposed adjacent the front end;

a hub extension disposed adjacent the rear end, the hub extension having an impeller bore and a first outer surface; and

blades disposed between the nose and the hub extension;

an insert screwed into the impeller bore, wherein the insert includes:

a first insert portion disposed within the impeller bore, the first insert portion having a threaded insert bore; and

a second insert portion disposed outside the impeller bore, the second insert portion having a second outer surface

a shaft extending from a first shaft end to a second shaft end, the shaft being attached to the insert adjacent the first shaft end; and

an impeller cap, having:

a first cap bore that engages with the first outer surface, the first cap bore and the first outer surface include an anti-rotational feature; and

a second cap bore that engages with the second outer surface.

11. The compressor impeller assembly of claim 10 , wherein

the impeller cap extends from a first cap end to a second cap end,

the first cap bore is disposed adjacent the first cap end, and

the shaft includes:

a first shaft portion having a threaded region that engages with the threaded insert bore; and

a second shaft portion having a first shoulder disposed adjacent the second cap end.

12. The compressor impeller assembly of claim 11 , wherein

the impeller cap further includes a cap pilot extending from the second cap end to a second shoulder disposed between the first cap end and the second cap end, and

the compressor impeller assembly further includes a thrust washer disposed between the first shoulder and the second shoulder.

13. The compressor impeller assembly of claim 12 , wherein the thrust washer includes a washer bore that engages with a third outer surface of the cap pilot, the washer bore and the third outer surface having an anti-rotational feature.

14. A turbocharger, comprising:

a turbine housing;

a turbine wheel disposed within the turbine housing and configured to be rotated by exhaust received from an engine;

a compressor housing;

a compressor impeller disposed within the compressor housing, the compressor impeller including a hub extension having an impeller bore and a first outer surface, wherein the impeller bore is a first impeller bore having a first diameter, and the compressor impeller includes:

a front end and a rear end opposite the front end, the hub extension extending from the rear end to a first distal end disposed between the front end and the rear end;

a second impeller bore having a second diameter, the second impeller bore extending from the front end to a second distal end disposed between the front end and the first distal end; and

a third impeller bore having a third diameter smaller than the first diameter and the second diameter, the third impeller bore extending from the first distal end to the second distal end;

an insert including:

a first insert portion disposed within the impeller bore, the first insert portion having a threaded insert bore having a first pitch; and

a second insert portion disposed outside the impeller bore, the second insert portion having a second outer surface;

an impeller cap extending from a first cap end to a second cap end, the impeller cap including:

a cap portion disposed adjacent the first cap end and engages with the first outer surface; and

a cap bore disposed between the first cap end and the second cap end, the cap bore engages with the second outer surface;

a thrust washer disposed adjacent the second cap end;

a shaft extending from a first shaft end to a second shaft end, the shaft being attached to the turbine wheel adjacent the second shaft end, the shaft including a threaded shaft bore having a second pitch different from the first pitch, the threaded shaft bore being disposed between the first shaft end and the second shaft end; and

a stud, including:

a first threaded portion engaged with the threaded insert bore; and

a second threaded portion engaged with the threaded shaft bore.

15. The turbocharger of claim 14 , wherein the second impeller bore further includes:

a first annular recess having a first radius, the first annular recess being disposed at a first axial distance from the front end;

a second annular recess having a second radius smaller than the first radius, the second annular recess being disposed at a second axial distance from the front end, the second axial distance being larger than the first axial distance;

a first seal member is disposed in the first annular recess; and

a second seal member is disposed in the second annular recess.