Decoupler assembly having limited overrunning capability

摘要

In one aspect, a decoupler assembly is provided for use between a shaft and an endless drive member that is used to drive the shaft. The decoupler assembly includes a pulley, a hub and an isolator spring that is preferably a coiled torsion spring. The two ends of the spring are engageable, at least indirectly, with the pulley and the hub for the transfer of torque therebetween. At least one of the ends of the spring engages an engagement structure (on either the pulley or the hub) that includes a helical axial shoulder and a driver wall. The spring transfers torque in one direction through the driver wall (e.g. when the pulley overruns the hub), but the spring end is not fixedly connected to the driver wall. When the hub overruns the pulley, there is relative rotation between the spring and whichever of the hub and pulley it is not fixedly connected to. Accordingly, there is relative rotation between the spring end and the helical axial shoulder and the driver wall. This causes the spring end to separate from the driver wall and ride up the helical axial shoulder. This causes the spring to compress axially. The spring coils have a selected amount of spacing so that the spring can be compressed by a selected amount axially. This sets the amount of relative rotation (and the amount of overrun) that is available between the pulley and the hub in the situation when the hub overruns the pulley. In some embodiments, the decoupler assembly may be configured such that the selected amount of spacing of the spring coils sets the amount of relative rotation (and therefore overrun) that is available between the pulley and the hub when the pulley overruns the hub.

主权项

1. A decoupler assembly for transferring torque between a shaft and an endless drive member, said decoupler assembly comprising:
a hub that is adapted to be coupled to the shaft such that the shaft co-rotates with the hub about a rotational axis; a pulley rotatably coupled to the hub, the pulley having an outer periphery that is adapted to engage the endless drive member; a helical torsion spring having a first axial face and a second axial face, and having a plurality of coils which are spaced apart by a plurality of gaps; a first engagement structure positioned between the torsion spring and one of the hub and the pulley, wherein the first engagement structure includes a helical first axial shoulder for engaging the first axial face of the torsion spring; and a second engagement structure positioned between the torsion spring and the other of the hub and the pulley, wherein the second engagement structure includes a second axial shoulder engageable with the second axial face of the torsion spring, wherein rotation of the one of the hub and the pulley in a first rotational direction relative to the other of the hub and the pulley drives rotation of the other of the hub and the pulley through the torsion spring, and wherein rotation of the other of the hub and the pulley in the first direction relative to said one of the hub and the pulley generates relative rotation between the torsion spring and the helical first axial shoulder which causes axial compression of the torsion spring between the first and second axial shoulders, wherein the plurality of gaps are sized to permit a selected amount of axial compression of the torsion spring such that there is a selected finite amount of relative rotation available between the hub and the pulley prior to lock up of the spring due to elimination of the gaps from axial compression.