# US 9,518,646 B2 · Decoupler assembly having limited overrunning capability > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,646 B2 - Document ID: US9518646B2 - Status: Granted - Kind: B2 - Application number: 14/697,487 - Filed: 2015-04-27 - Published: 2015-08-13 - Granted: 2016-12-13 - Earliest claimed: 2010-11-09 - Assignees: Litens Automotive Partnership - Applicants: Litens Automotive Partnership - Inventors: Patrick Marion - Web page: https://patentgrep.com/patent/US9518646B2 ## CPC - F16H 55/36: Pulleys (with features essential for adjustment F16H55/52) - B60K 25/02: directly from an engine shaft - B60K 26/02: of initiating means or elements - F02B 67/06: driven by means of chains, belts, or like endless members - F16D 3/10: Couplings with means for varying the angular relationship of two coaxial shafts during motion - F16D 3/12: specially adapted for accumulation of energy to absorb shocks or vibration (by making use of fluid elements F16D3/80) - F16D 7/00: Slip couplings, e.g. slipping on overload, for absorbing shock (combined with yielding shaft couplings F16D3/14; fluid slip couplings F16D31/00 - F16D35/00) - F16D 41/206: {having axially adjacent coils, e.g. helical wrap-springs} - F16F 15/1216: {Torsional springs, e.g. torsion bar or torsionally-loaded coil springs} - B60K 2025/022: {by a mechanical transmission} - F16H 2055/363: {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} - F16H 2055/366: {with means providing resilience or vibration damping} - F16H: GEARING - B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION ## 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. 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) 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. ### Claim 4 (depends on 1) 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. ### Claim 5 (depends on 1) 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. ### Claim 6 (depends on 1) 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. ### Claim 7 (depends on 1) 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. ### Claim 8 (depends on 1) 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. ### Claim 9 (depends on 1) A decoupler as claimed in claim 1, further comprising a bearing positioned between the pulley and the hub. ### Claim 10 (depends on 1) A decoupler as claimed in claim 1, further comprising a bushing positioned between the pulley and the hub. ### Claim 11 (depends on 1) A decoupler as claimed in claim 1, further comprising a sleeve positioned radially outside the torsion spring and having a selected friction coefficient. ### Claim 12 (depends on 1) 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. ### Claim 13 (depends on 1) 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. ### Claim 14 (depends on 1) 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. ### Claim 15 (depends on 1) 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. ### Claim 16 (depends on 15) 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. ### Claim 17 (depends on 15) 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. ### Claim 18 A belt-alternator-start system for a vehicle, the vehicle including an engine having a crankshaft, and having a crankshaft pulley, and a belt that is engaged with the crankshaft pulley and with an alternator, the belt-alternator starting system comprising: a decoupler assembly mountable to the shaft of the alternator, and wherein the decoupler assembly includes: 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, 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.