Overrunning Alternator Decoupler Pulley with Bare Wire Spring and Grease Lubrication

Abstract

A decoupler assembly is provided for a system that employs an endless power transmitting element. The decoupler includes a one-way clutch with a wrap spring and a torsion spring that are disposed between a pulley, which is engaged to the endless power transmitting element, and a hub. The one-way clutch permits overrunning of a driven or output one of the pulley and the hub, whereas the torsion spring stores and releases energy to attenuate the response of the one-way clutch in a manner that provides improved durability of an interface between the wrap spring and the pulley.

1 - 29 . (canceled) 
   
   
       30 . A decoupler assembly comprising:
 a hub that is adapted to be coupled to a shaft such that the shaft co-rotates with the hub;   a carrier that is rotatable relative to the hub;   at least one torsion spring between the hub and the carrier;   a pulley having an outer periphery, which is adapted to engage an endless power transmitting element, and an inner surface; and   a clutch spring formed only of wire, the clutch spring having a first end that is received in a groove formed in the carrier, a second end opposite the first end and a plurality of coils between the first and second ends, the clutch spring exiting the carrier and extending toward the inner surface of the pulley such that at least one of the plurality of coils is engaged against the inner surface of the pulley when rotary power is transmitted between the pulley and the hub, the plurality of coils contracting to reduce gripping engagement with the inner surface of the pulley in response to deceleration of the pulley relative to the carrier beyond a predetermined extent.   
   
   
       31 . The decoupler assembly of  claim 30 , wherein the clutch spring exits the carrier in a radially outward direction. 
   
   
       32 . The decoupler assembly of  claim 30 , wherein the at least one torsion spring and the clutch spring are coiled in opposite directions. 
   
   
       33 . The decoupler assembly of  claim 30 , wherein the at least one torsion spring uncoils as a magnitude of the rotary power transmitted between the carrier and the hub increases. 
   
   
       34 . The decoupler assembly of  claim 33 , wherein at least one of the carrier and the hub includes a tapered ramp and an abutting wall that is perpendicular to the tapered ramp and wherein the at least one torsion spring abuts each of the abutting walls. 
   
   
       35 . The decoupler assembly of  claim 30 , wherein the carrier is mounted on the hub. 
   
   
       36 . The decoupler assembly of  claim 30 , wherein the wire has a cross-sectional shape with an outer side that abuts the inner surface of the pulley, the outer side having a contour that is configured to distribute load transmitted from the clutch spring to the pulley over multiple points of contact spaced along the outer side. 
   
   
       37 . The decoupler assembly of  claim 36 , wherein the outer side has a flat contour. 
   
   
       38 . The decoupler assembly of  claim 37 , wherein the wire has a square cross-sectional shape or a rectangular cross-sectional shape. 
   
   
       39 . The decoupler assembly of  claim 30 , wherein the wire has a cross-sectional shape with an outer side, which abuts the inner surface of the pulley, and lateral sides that are coupled to the opposite lateral sides of the outer side, the lateral sides having a flat contour. 
   
   
       40 . The decoupler assembly of  claim 39 , wherein the wire has a square cross-sectional shape or a rectangular cross-sectional shape. 
   
   
       41 . The decoupler assembly of  claim 30 , wherein the at least one torsion spring is axially compressed between the carrier and the hub. 
   
   
       42 . The decoupler assembly of  claim 30 , further comprising a bearing disposed between the hub and the pulley. 
   
   
       43 . The decoupler assembly of  claim 30 , wherein the plurality of coils are abutted against one another. 
   
   
       44 . The decoupler assembly of  claim 30 , further comprising a torsional vibration damper fixed for rotation with the hub. 
   
   
       45 . The decoupler assembly of  claim 30 , wherein the groove is formed on an axial end face of the carrier. 
   
   
       46 . The decoupler assembly of  claim 30 , further comprising a lubricant disposed on coils of the clutch spring. 
   
   
       47 . The decoupler assembly of  claim 46 , wherein the lubricant is a grease. 
   
   
       48 . The decoupler assembly of  claim 46 , wherein the clutch spring exits the carrier in a radially outward direction. 
   
   
       49 . The decoupler assembly of  claim 46 , wherein the at least one torsion spring and the clutch spring are coiled in opposite directions. 
   
   
       50 . The decoupler assembly of  claim 46 , wherein the at least one torsion spring uncoils as a magnitude of the rotary power transmitted between the carrier and the hub increases. 
   
   
       51 . The decoupler assembly of  claim 50 , wherein at least one of the carrier and the hub includes a tapered ramp and an abutting wall that is perpendicular to the tapered ramp and wherein the at least one torsion spring abuts each of the abutting walls. 
   
   
       52 . The decoupler assembly of  claim 46 , wherein the carrier is mounted on the hub. 
   
   
       53 . The decoupler assembly of  claim 46 , wherein the wire has a cross-sectional shape with an outer side that abuts the inner surface of the pulley, the outer side having a contour that is configured to distribute load transmitted from the clutch spring to the pulley over multiple points of contact spaced along the outer side. 
   
   
       54 . The decoupler assembly of  claim 53 , wherein the outer side has a flat contour. 
   
   
       55 . The decoupler assembly of  claim 54 , wherein the wire has a square cross-sectional shape or a rectangular cross-sectional shape. 
   
   
       56 . The decoupler assembly of  claim 46 , wherein the wire has a cross-sectional shape with an outer side, which abuts the inner surface of the pulley, and lateral sides that are coupled to the opposite lateral sides of the outer side, the lateral sides having a flat contour. 
   
   
       57 . The decoupler assembly of  claim 56 , wherein the wire has a square cross-sectional shape or a rectangular cross-sectional shape. 
   
   
       58 . The decoupler assembly of  claim 46 , wherein the at least one torsion spring is axially compressed between the carrier and the hub. 
   
   
       59 . The decoupler assembly of  claim 46 , further comprising a bearing disposed between the hub and the pulley. 
   
   
       60 . The decoupler assembly of  claim 46 , wherein the plurality of coils are abutted against one another. 
   
   
       61 . The decoupler assembly of  claim 46 , further comprising a torsional vibration damper fixed for rotation with the hub. 
   
   
       62 . The decoupler assembly of  claim 46 , wherein the groove is formed on an axial end face of the carrier. 
   
   
       63 . A decoupler assembly comprising:
 a hub that is adapted to be coupled to a shaft such that the shaft co-rotates with the hub;   a carrier that is rotatably mounted on the hub;   at least one torsion spring between the carrier and the hub;   a pulley having an outer periphery, which is adapted to engage an endless power transmitting element, and an inner surface; and   a clutch spring formed only of wire, the clutch spring having a plurality of coils, wherein less than one complete coil is engaged to the carrier, wherein at least one of the plurality of coils is engaged against the inner surface of the pulley when rotary power is transmitted between the pulley and the hub, at least a portion of the plurality of coils contracting to reduce gripping engagement with the inner surface of the pulley in response to deceleration of the pulley relative to the carrier beyond a predetermined extent.   
   
   
       64 . The decoupler assembly of  claim 63 , further comprising a lubricant disposed on coils of the clutch spring. 
   
   
       65 . The decoupler assembly of  claim 64 , wherein the lubricant is a grease.