Decoupler with spring travel limiter

Abstract

A decoupler having an output member, a one-way clutch, a spring and a spring limiter. The spring is disposed between an output portion of the one-way clutch and the output member to bias the output portion in a predetermined rotational direction relative to the output member. The spring limiter can be configured to lock an output of the one-way clutch to the output member to transmit rotary power between the one-way clutch and the output member without stressing the spring beyond a predetermined point and/or to limit rotational movement of the output portion and an associated end of the spring relative to the output member in the predetermined rotational direction. A method for operating a decoupler is also provided.

What is claimed is: 
     
       1. A decoupler comprising:
 a hub that is rotatable about an axis; 
 a pulley disposed concentrically about the hub and rotatable about the axis; 
 a one-way clutch having an input member and an output member, the one-way clutch permitting transmission of rotary power from the pulley to the output member, but not from the output member to the pulley; and 
 a torsion spring disposed between the output member of the one-way clutch and the hub to transmit rotary power from the output member to the hub; 
 wherein the output member of the one-way clutch is rotatable relative to the hub about the axis between a first position and a second position, wherein positioning of the output member in a first position locks the output member to the hub so that rotary power transmitted through the torsion spring is limited to a predetermined maximum torque, and wherein all rotary power transmitted through the one-way clutch is transmitted to the hub through the torsion spring when the output member is positioned between the first and second positions. 
 
     
     
       2. The decoupler of  claim 1 , wherein the torsion spring is received axially over the hub. 
     
     
       3. The decoupler of  claim 2 , wherein the torsion spring is axially compressed between the output member and the hub. 
     
     
       4. The decoupler of  claim 3 , further comprising a thrust washer fixed to the hub and abutting the output member. 
     
     
       5. The decoupler of  claim 4 , wherein the first and second positions are established by contact between the thrust washer and the output member. 
     
     
       6. The decoupler of  claim 1 , wherein the one-way clutch comprises a wrap spring that is mounted to the output member. 
     
     
       7. The decoupler of  claim 1 , wherein a diameter of the torsion spring tends to increase as a magnitude of the rotary power increases to the predetermined maximum torque. 
     
     
       8. The decoupler of  claim 1 , wherein rotation of the torsion spring relative to the hub and the output member is inhibited when the output member is in the second position. 
     
     
       9. A decoupler comprising:
 a hub that is rotatable about an axis; 
 a pulley disposed concentrically about the hub and rotatable about the axis; 
 a one-way clutch having an input member and an output member, the one-way clutch allowing transmission of rotary power from the pulley to the output member but not facilitating transmission of rotary power from the hub to the pulley; 
 a spring disposed between the output member and the hub and configured to transmit rotary power therebetween, the spring biasing the output member in a predetermined rotational direction relative to the hub; 
 wherein the output member of the one-way clutch is rotatable relative to the hub about the axis between a first position and a second position, wherein all rotary power transmitted to the hub is transmitted through the spring when the output member is positioned between the first and second positions, and wherein rotational movement of both the output member and an end of the spring that is engaged to the output member in the predetermined rotational direction relative to the hub is inhibited when the output member is in the second position. 
 
     
     
       10. The decoupler of  claim 9 , wherein the spring is received axially over the hub. 
     
     
       11. The decoupler of  claim 10 , wherein the spring is axially compressed between the output member and the hub. 
     
     
       12. The decoupler of  claim 11 , further comprising a thrust washer fixed to the hub and abutting the output member. 
     
     
       13. The decoupler of  claim 12 , wherein the first and second positions are established by contact between the thrust washer and the output member. 
     
     
       14. The decoupler of  claim 9 , wherein the one-way clutch comprises a wrap spring that is mounted to the output member. 
     
     
       15. The decoupler of  claim 9 , wherein a diameter of the spring tends to increase as a magnitude of the rotary power increases to the predetermined maximum torque. 
     
     
       16. A decoupler comprising:
 a hub that is rotatable about an axis;   a pulley disposed concentrically about the hub and rotatable about the axis; and   an isolator received between and coupling the hub and the pulley, the isolator having a torsionally-resilient coupling coupled in series with a one-way clutch assembly, the one-way clutch assembly having an input member and an output member, the one-way clutch assembly permitting transmission of rotary power in a direction from the pulley to the output member, but not in a direction from the output member to the pulley;   wherein a portion of the isolator is rotatable relative to the hub about the axis between a first position and a second position, wherein positioning of the portion of the isolator in the second position locks the isolator so that rotary power transmitted through the torsionally-resilient coupling is limited to a predetermined maximum torque, and wherein all rotary power transmitted through the isolator is transmitted to the hub through the torsionally-resilient coupling when the portion of the isolator is not positioned in the second position.    
     
     
       17. The decoupler of claim 16, wherein the torsionally-resilient coupling comprises a torsion spring.  
     
     
       18. The decoupler of claim 17, wherein the one-way clutch assembly comprises a wrap spring.  
     
     
       19. The decoupler of claim 18, wherein the wrap spring is mounted to the output member.  
     
     
       20. The decoupler of claim 16, wherein the torsionally-resilient coupling is axially compressed.  
     
     
       21. The decoupler of claim 20, further comprising a thrust washer fixed to the hub and abutting the output member.  
     
     
       22. The decoupler of claim 21, wherein the first and second positions are established by contact between the thrust washer and the output member.  
     
     
       23. The decoupler of claim 16, wherein the one-way clutch assembly comprises a wrap spring.  
     
     
       24. The decoupler of claim 16, wherein the portion of the isolator comprises the output member of the one-way clutch assembly.  
     
     
       25. The decoupler of claim 16, wherein the isolator is oriented in the decoupler such that rotary power is transmitted from the pulley to the one-way clutch assembly into the torsionally resilient coupling and to the hub when the portion of the isolator is not positioned in the second position.  
     
     
       26. A decoupler assembly for transferring torque between a drive shaft and an endless drive element of an automotive engine, the decoupler assembly comprising:
 a hub adapted to be fixedly secured to the shaft, the hub extending axially between a first hub end and a second hub end;   a pulley disposed concentrically about the hub and adapted to be drivingly engaged with the endless drive element;   a bearing between the hub and the pulley, the bearing supporting the pulley for rotation about a rotational axis of the hub;   an isolator received between and coupling the hub and the pulley, the isolator having a torsion spring coupled in series with a one-way clutch assembly, the one-way clutch assembly permitting transmission of rotary power in a direction from the pulley to the output member, but not in a direction from the hub to the pulley; and   an anti-ramp up mechanism having a first anti-ramp up feature, which is coupled to an end of the torsion spring for rotation therewith, and a second anti-ramp up feature that is engageable with the first anti-ramp up feature, the first and second anti-ramp up features permitting rotation of the end of the torsion spring about the rotational axis in a first rotational direction from a first position to a second position, the first and second anti-ramp up features cooperating to inhibit rotation of the end of the torsion spring about the rotational axis in a second, opposite rotational direction away from the first position.    
     
     
       27. The decoupler assembly of claim 26, wherein the spring is axially compressed.  
     
     
       28. The decoupler assembly of claim 26, wherein one of the first and second anti-ramp up features comprises a slot and the other one of the first and second anti-ramp up features comprises a post that is received in the slot.  
     
     
       29. The decoupler assembly of claim 26, wherein the second anti-ramp up feature is non-rotatably coupled to the hub.  
     
     
       30. The decoupler assembly of claim 26, wherein the one-way clutch assembly comprises a wrap spring.  
     
     
       31. The decoupler of claim 26, wherein the isolator is oriented in the decoupler such that rotary power is transmitted from the pulley to the one-way clutch assembly into the torsionally resilient coupling and to the hub when the end of the spring is disposed between the first and second positions.  
     
     
       32. A decoupler comprising:
 a hub;   a pulley rotatably journalled to the hub;   an isolator coupling the pulley to the hub, the isolator comprising a torsion spring connected in series with a one-way clutch via a carrier, wherein the one-way clutch permits rotary power to flow from the pulley to the hub but not from the hub to the pulley;   wherein the carrier includes an abutment wall and the torsion spring includes a distal end which presses against the abutment wall, the carrier further including one of a boss and a slot, the one of the boss and the slot having an anti-ramp up side and a torque lock-up side, wherein contact between a first side of a complementary feature and the anti-ramp up side limits an angular position of the carrier along a first rotational direction so as to prevent the distal end of the torsion spring from backing away from the carrier abutment wall, and wherein contact between a second side of the complementary feature and the torque lock-up side limits the angular position of the carrier along a second rotational direction so as to prevent twist of the torsion spring beyond a design spring twist angle.    
     
     
       33. The decoupler of claim 32, wherein the complementary feature is the other one of the boss and the slot.  
     
     
       34. The decoupler of claim 32, wherein the one-way clutch comprises a wrap spring.  
     
     
       35. The decoupler of claim 32, wherein the complementary feature is coupled to a structure that contacts a member of the clutch so that rotary power is transmitted directly between the one-way clutch and the structure.  
     
     
       36. The decoupler of claim 35, wherein the structure is coupled to the hub for rotation therewith.  
     
     
       37. A decoupler comprising:
 a hub;   a pulley;   an isolator coupling the pulley to the hub, the isolator comprising a torsion spring connected in series with a one-way clutch assembly, the one-way clutch assembly being configured to permit transmission of rotary power from the pulley to the hub to drive the hub in a first rotational direction and being configured to interrupt transmission of rotary power from the hub to the pulley to permit the hub to overrun the pulley in the first rotational direction;   wherein the one-way clutch assembly includes an abutment wall and the torsion spring includes a distal end which presses against the abutment wall, the one-way clutch further including one of a boss and a slot, the one of the boss and the slot having an anti-ramp up side and a torque lock-up side, wherein contact between a first side of a complementary feature and the anti-ramp up side limits an angular position of the abutment wall along a first rotational direction so as to prevent the distal end of the torsion spring from backing away from the abutment wall, and wherein contact between a second side of the complementary feature and the torque lock-up side limits twist of the torsion spring beyond a design spring twist angle.    
     
     
       38. The decoupler of claim 37, wherein the complementary feature is the other one of the boss and the slot.  
     
     
       39. The decoupler of claim 37, wherein the one-way clutch comprises a wrap spring.  
     
     
       40. The decoupler of claim 37, wherein the complementary feature is coupled to a structure that contacts a member of the clutch so that rotary power is transmitted directly between the one-way clutch and the structure.  
     
     
       41. The decoupler of claim 40, wherein the structure is coupled to the hub for rotation therewith.