Decoupler assembly having limited overrunning capability

Patent metadata

Field	Value
Publication number	US-9046133-B2
Application number	US-201113877604-A
Country	US
Kind code	B2
Filing date	Nov 8, 2011
Priority date	Nov 9, 2010
Publication date	Jun 2, 2015
Grant date	Jun 2, 2015

Abstract

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.

First claim

What is claimed is:

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 concentric with the rotational axis and 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 pulley in a first rotational direction relative to the hub drives rotation of the hub through the torsion spring, and wherein rotation of the hub in the first direction relative to 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 provide 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.

2. A decoupler assembly as claimed in claim 1 , wherein the selected amount of compression of the torsion spring is reached in less than 360 degrees of rotation of the hub relative to the pulley.

3. A decoupler assembly as claimed in claim 1 , wherein the selected amount of axial compression of the torsion spring generates a selected increase in a frictional force at the helical first axial shoulder.

4. A decoupler as claimed in claim 1 , wherein the torsion spring has a first helical end and a second helical end, and wherein the first engagement structure includes a first radial shoulder and the second engagement structure includes a second radial shoulder, wherein the first and second generally radial shoulders are positioned to engage at least indirectly the first and second helical ends respectively during rotation of the pulley in the first rotational direction relative to the hub, and wherein the first radial shoulder is spaced from the first helical end during rotation of the hub in the first rotational direction relative to the pulley.

5. A decoupler as claimed in claim 1 , wherein the torsion spring has a first helical end and a second helical end, and the first engagement structure includes a first radial shoulder that is engageable with the first helical end of the spring, and the second engagement structure is rotationally fixedly connected with the second helical end of the spring.

6. A decoupler as claimed in claim 1 , wherein the first engagement structure is integral with the pulley and the second engagement structure is integral with the hub.

7. A decoupler as claimed in claim 1 , wherein the first engagement structure is integral with the hub and the second engagement structure is integral with the pulley.

8. A decoupler as claimed in claim 1 , further comprising a carrier positioned between the second helical end of the torsion spring and the other of the hub and the pulley, wherein the second engagement structure is integral with the carrier.

9. A decoupler as claimed in claim 1 , further comprising a bearing positioned between the pulley and the hub.

10. A decoupler as claimed in claim 1 , further comprising a bushing positioned between the pulley and the hub.

11. A decoupler as claimed in claim 1 , further comprising a sleeve positioned radially outside the torsion spring and having a selected friction coefficient.

12. A decoupler as claimed in claim 1 , wherein the selected amount of compression of the torsion spring is reached in more than about 50 degrees of rotation of the hub relative to the pulley.

13. A decoupler as claimed in claim 1 , wherein the selected amount of compression of the torsion spring is reached in more than about 70 degrees of rotation of the hub relative to the pulley.

14. A decoupler as claimed in claim 1 , further comprising a carrier positioned between the first helical end of the torsion spring and the one of the hub and the pulley, wherein the first engagement structure is integral with the carrier.

15. A decoupler as claimed in claim 1 , further comprising:
a first carrier positioned between the first helical end of the torsion spring and the one of the hub and the pulley, and
a second carrier positioned between the second helical end of the torsion spring and the other of the hub and the pulley.

16. A decoupler as claimed in claim 15 , wherein the first carrier is fixedly mounted to the one of the hub and the pulley and the first engagement structure is integral with the first carrier.

17. A decoupler as claimed in claim 15 , wherein the first carrier is fixedly mounted to the torsion spring and the first carrier engages the helical axial first shoulder.

Assignees

• Marion Patrick
• Litens Automotive Inc

Inventors

• Marion Patrick

Classifications

• F16D7/00 Primary

  Slip couplings, e.g. slipping on overload, for absorbing shock (combined with yielding shaft couplings F16D3/14; fluid slip couplings F16D31/00 - F16D35/00) · CPC title

• F16H2055/363

  with special means or properties for lateral tracking of the flexible members running on the pulley, e.g. with crowning to keep a belt on track · CPC title

• B60K2025/022

  by a mechanical transmission · CPC title

• B60K25/02

  directly from an engine shaft · CPC title

• F16D41/206

  having axially adjacent coils, e.g. helical wrap-springs · CPC title