Vehicle input shafts

1. An input shaft for a vehicle drive line comprising: a first shaft end; a bearing boss at the first shaft end comprising a generally spherical surface having an increased diameter at a central point along its axial length and decreased diameters at a first bearing boss end at the first shaft end and a second bearing boss end adjacent the first spline end of the spline portion; a spline portion having a first spline end adjacent to the first shaft end and a second spline end, the spline portion comprising multiple spline teeth extending in a direction parallel with a longitudinal axis of the input shaft and extending radially away from the longitudinal axis, and multiple radially indented spline grooves located circumferentially between adjacent ones of the spline teeth extending in a direction parallel with the longitudinal axis of the input shaft; a second shaft end; a substantially cylindrical shaft body extending from the second shaft end toward the second spline end; and a tapered transition between the second spline end and the shaft body, wherein each spline groove comprises a blend out fillet adjacent the second spline end extending radially outward from a bottom surface of the spline groove toward the shaft body; wherein the input shaft is a one piece shaft.

2. The input shaft of claim 1 , wherein each blend out fillet forms part of a radial outermost ring.

3. The input shaft of claim 2 , wherein the radial outermost ring formed by the blend out fillets has a diameter that is substantially equal to an outer diameter formed by radial outermost surfaces of the spline teeth.

4. The input shaft of claim 1 , wherein a radial outermost edge of each blend out fillet extends at least 50 percent of a radial distance between the bottom surface of the spline groove and radial outer surfaces of the adjacent spline teeth.

5. The input shaft of claim 4 , wherein the radial outermost edge of each blend out fillet extends at least 75 percent of a radial distance between the bottom surface of the spline groove and a radial outer surface of the spline teeth.

6. The input shaft of claim 1 , wherein each blend out fillet comprises a concave surface.

7. The input shaft of claim 1 , wherein the blend out fillet comprises a curved surface.

8. The input shaft of claim 7 , wherein the curved surface of the blend out fillet has a radius of curvature R F of from 0.25 to 1.5 inches.

9. The input shaft of claim 1 , wherein the blend out fillet comprises an axial length of from 0.05 to 0.75 inch, and a radial extension distance measured from the bottom surface of the spline groove of from 0.1 to 0.5 inch.

10. The input shaft of claim 9 , wherein the ratio of the axial length to radial extension distance of the blend out fillet is from 3:1 to 1:2.

11. The input shaft of claim 1 , wherein the tapered transition comprises a concave surface.

12. The input shaft of claim 1 , wherein the tapered transition comprises a curved surface.

13. The input shaft of claim 12 , wherein the curved surface of the tapered transition has a radius of curvature R s of from 0.25 to 1 inch.

14. The input shaft of claim 1 , wherein the tapered transition comprises an axial length of from 0.1 to 0.75 inch, and a radial extension distance of from 0.1 to 0.75 inch.

15. The input shaft of claim 14 , wherein the ratio of the axial length to radial extension distance of the tapered transition is from 3:1 to 1:3.

16. The input shaft of claim 1 , wherein the generally spherical surface of the bearing boss has a radius of curvature R B of from 2 to 5 inches.

17. A clutch assembly comprising:

a clutch plate cover structured and arranged for attachment to a flywheel of a vehicle engine;

at least one clutch disc inside the clutch plate cover;

an input shaft upon which the at least one clutch disc is mounted for rotation with the input shaft and sliding engagement along a longitudinal axis of the input shaft, wherein the input shaft comprises:

a first shaft end;

a bearing boss at the first shaft end of the input shaft engageable within a pilot bearing of the flywheel, wherein the bearing boss comprises a generally spherical surface having an increased diameter at a central point along its axial length and decreased diameters at a first bearing boss end at the first shaft end and a second bearing boss end adjacent the first spline end of the spline portion;

a spline portion having a first spline end adjacent to the first shaft end and a second spline end, the spline portion comprising multiple spline teeth extending in a direction parallel with a longitudinal axis of the input shaft and extending radially away from the longitudinal axis, and multiple radially indented spline grooves located circumferentially between adjacent ones of the spline teeth extending in a direction parallel with the longitudinal axis of the input shaft;

a second shaft end;

a substantially cylindrical shaft body extending from the second shaft end toward the second spline end; and

a tapered transition between the second spline end and the shaft body.

18. An input shaft for a vehicle drive line comprising: a first shaft end; a bearing boss at the first shaft end comprising a generally spherical surface having an increased diameter at a central point along its axial length, a decreased diameter at a first bearing boss end located at the first shaft end, and decreased diameter at a second bearing boss end; a spline portion having a first spline end adjacent to the second bearing boss end and a second spline end, the spline portion comprising multiple spline teeth extending in a direction parallel with a longitudinal axis of the input shaft and extending radially away from the longitudinal axis, and multiple radially indented spline grooves located circumferentially between adjacent ones of the spline teeth extending in a direction parallel with the longitudinal axis of the input shaft; a second shaft end; a substantially cylindrical shaft body extending from the second shaft end toward the second spline end; and a tapered transition between the second spline end and the shaft body; wherein the input shaft is a one piece shaft.

19. The clutch assembly of claim 17 , wherein each spline groove comprises a blend out fillet adjacent the second spline end extending radially outward from a bottom surface of the spline groove toward the shaft body.

20. The input shaft of claim 18 , wherein the generally spherical surface of the bearing boss has a radius of curvature R B of from 2 to 5 inches.