Isolating decoupler

1. An isolator decoupler comprising:

a shaft ( 1 );

a pulley ( 2 ) journalled to the shaft;

a torsion spring ( 10 ) engaged between the pulley and a carrier ( 9 ), the torsion spring loaded in an unwinding direction;

a wrap spring ( 11 ) engaged between the carrier and the shaft;

the wrap spring comprising a cylindrical inner portion ( 94 ) and a planar outer portion ( 93 ) connected by a tapered portion ( 155 ); and

the inner portion frictionally engaged with the shaft in a winding direction.

2. The isolator decoupler as in claim 1 , wherein the tapered portion extends tangentially to the inner portion.

3. The isolator decoupler as in claim 1 , wherein the inner portion comprises a plurality of coils.

4. The isolator decoupler as in claim 1 , wherein the pulley is temporarily engagable with the inner portion such that the magnitude of a frictional engagement between the inner portion and the shaft is progressively reduced upon a pressing contact by the pulley.

5. The isolator decoupler as in claim 1 , wherein the outer portion is disposed within a carrier receiving portion.

6. The isolator decoupler as in claim 1 , wherein a cross-section of the inner portion is less than the cross-section of the outer portion.

7. An isolator decoupler comprising:

a shaft;

a pulley journalled to the shaft;

a torsion spring engaged between the pulley and a carrier, the torsion spring loaded in an unwinding direction;

a wrap spring engaged between the carrier and the shaft;

the wrap spring comprising a cylindrical inner portion extending axially and a coplanar outer portion connected to the inner portion by a tapered portion;

the inner portion frictionally engaged with the shaft in a winding direction; and

the pulley temporarily engagable with the inner portion such that the magnitude of a frictional engagement between the inner portion and the shaft is incrementally reduced upon an increase in torque applied to the pulley.

8. The isolator decoupler as in claim 7 , wherein the tapered portion extends tangentially to the inner portion.

9. The isolator decoupler as in claim 7 , wherein a cross-section of the inner portion is dimensionally smaller than the outer portion.

10. An isolator decoupler comprising:

a shaft;

a pulley journalled to the shaft;

a torsion spring engaged between the pulley and a carrier, the torsion spring loaded in an unwinding direction;

a wrap spring engaged between the carrier and the shaft;

the wrap spring comprising a cylindrical inner portion and a planar spiral outer portion connected by a tangential portion;

the inner portion frictionally engaged with the shaft in an inner portion winding direction; and

the inner portion incrementally releasable from the frictional engagement with the shaft upon a pressing contact by the pulley.

11. The isolator decoupler as in claim 10 , wherein the outer portion is disposed within a carrier receiving portion.

12. The isolator decoupler as in claim 10 , wherein a cross-section of the inner portion is dimensionally smaller than the outer portion.

13. The isolator decoupler as in claim 10 further comprising:

a first thrust member and second thrust member axially constraining the pulley on the shaft; and

an end member retaining the pulley on the shaft.

14. The isolator decoupler as in claim 10 , wherein the tangential portion is tapered.

15. The isolator decoupler as in claim 10 , wherein the inner portion comprises a plurality of coils extending along a rotational axis A-A.

16. An isolator decoupler comprising:

a shaft;

a pulley journalled to the shaft;

a spring engaged between the pulley and a carrier, the spring loaded in an unwinding direction;

a wrap spring engaged between the carrier and the shaft;

the wrap spring comprising a cylindrical inner portion and a planar spiral outer portion, the outer portion engaged with the carrier;

the inner portion frictionally engaged with the shaft in a winding direction; and

the inner portion frictional engagement incrementally releasable from the shaft upon application of an incremental pressure by the pulley to the inner portion.