Decoupler shaft and air turbine starter having such a decoupler
AssigneeAllied-Signal Inc.
InventorsDavid L. Laessle, Todd S. Carlson, Andrew J. Krochmalny, Leroy C. Anderson
Life of this patent
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Abstract
A torque limiting decoupler shaft transmits driving torque in a first sense without torque limiting action. However, torque applied to the shaft in a reverse sense opposite the driving torque results in an axial separating force between two portions of the decoupler shaft. When the reverse torque reaches a certain level a frangible tensile bar member fractures to permit decoupling of the shaft portions. A component of the shaft prevents undesirable recoupling of the shaft portions while also insuring that the relatively rotating portions of the shaft do not flail. An air turbine starter includes such a decoupler shaft.
Claims20
A decoupler shaft comprising:
- a first and a second axially adjacent elongate and coaxial shaft portions, each one of said shaft portions defining respective torque transmitting coupling means for inter-engaging with one of a respective driving mechanism and driven mechanism, said shaft portions also each defining respective driving surfaces and ramp surfaces interengaging in a first relative position of said shaft portions and both extending radially, said driving surfaces of said shaft portions extending substantially axially to transmit driving torque in a first sense between said shaft portions, said ramp surfaces extending both axially and circumferentially to transmit reverse torque in a second sense opposite said first sense with a resulting axial separating force between said shaft portions, a frangible tensile bar member extending between said shaft portions to retain the latter in said first relative position in opposition to said separating force, upon said reverse torque reaching a certain level said tensile bar fracturing to allow said separating force to relatively move said shaft portions to a second spaced apart relative position wherein said driving and ramp surfaces do not interengage.
An air turbine starter comprising a housing, said housing defining an inlet and outlet, and a first flow path extending between said inlet and said outlet for communicating a flow of pressurized motive gas therethrough;
- a turbine member journaled within said housing and disposed within said flow path for rotatably extracting mechanical power from said motive gas flow, speed reduction gear train means having a high speed gear member drivingly coupled with said turbine member and a comparatively low speed output member, one way overrunning clutch means coupling said output member with an output shaft while allowing overrunning of the latter said output shaft coupling with a decoupler shaft assembly, said decoupler shaft assembly including a pair of coaxial axially adjacent shaft portions, said shaft portions defining first cooperating engagement means for transmitting torque therebetween in a first sense substantially without resulting axial force between said shaft portions, and said shaft portions also defining second cooperating engagement means for transmitting torque therebetween in a second sense opposite said first sense and resulting in a proportionate axial separation force between said shaft portions, frangible tensile bar means extending between said pair of shaft portions for retaining the latter in a first cooperative position in opposition to said axial separating force wherein said shaft portions are not relatively rotatable, said tensile bar member fracturing in response to a determined torque of said second sense to permit axial separation of said shaft portions to a second position wherein said cooperating means do not engage and said shaft portions are relatively rotatable.
An air turbine starter including a decoupler shaft transmitting power therefrom to a combustion turbine engine while substantially preventing power transmission in the opposite direction, said decoupler shaft including a pair of coaxial axially adjacent shaft portions, said shaft portions defining first cooperating engagement means for transmitting torque therebetween in a first sense substantially without resulting axial force between said shaft portions, and said shaft portions also defining second cooperating engagement means for transmitting torque therebetween in a second sense opposite said first sense and resulting in as proportionate axial separation force between said shaft portions, frangible tensile bar means extending between said pair of shaft portions for retaining the latter in a first cooperative position in opposition to said axial separating force wherein said shaft portions are not relatively rotatable, said tensile bar member fracturing in response to a determined torque of said second sense to permit axial separation of said shaft portions to a second position wherein said cooperating means do not engage and said shaft portions are relatively rotatable.
Dependencies are inferred from the claim text.