Air turbine starter with decoupler

Patent metadata

Field	Value
Publication number	US-10584640-B2
Application number	US-201615180728-A
Country	US
Kind code	B2
Filing date	Jun 13, 2016
Priority date	Jun 13, 2016
Publication date	Mar 10, 2020
Grant date	Mar 10, 2020

Abstract

A method and decoupler for disengaging an output shaft from an engine in a back drive event with a backdrive decoupler. The backdrive decoupler includes a an output shaft, drive shaft, and a retention mechanism selectively coupling the output shaft to the drive shaft. In a backdrive event, the decoupler decouples the output shaft from the drive shaft.

First claim

The invention claimed is:

1. A decoupler assembly for decoupling an output shaft of a starter motor during backdrive, comprising:
a tensile fuse having a first end operably coupled to a drive shaft of the starter motor, a threaded portion receivable within an internal threaded portion of the output shaft of the starter motor, and a neck portion located between the first end and the threaded portion;
wherein when a driving torque is transmitted from the drive shaft to the output shaft the tensile fuse is not loaded, when overrunning torque is transmitted below a certain level the tensile fuse is partially loaded and when the overrunning torque reaches a certain level the tensile fuse shears at the neck portion and the threaded portion of the tensile fuse is unwound from the internal threaded portion in a direction away from the drive shaft.

2. The decoupler of claim 1 , further comprising a thread insert operably coupled to the drive shaft and having a threaded portion that receives a threaded portion of the output shaft of the starter motor.

3. The decoupler of claim 2 wherein the tensile fuse is threaded into the output shaft with an opposite hand turn to the threads between the output shaft and the thread insert.

4. The decoupler of claim 3 , wherein when the overrunning torque reaches the certain level the output shaft is unthreaded from the thread insert such that the output shaft is uncoupled from the drive shaft when the tensile fuse is unwound from the output shaft.

5. The decoupler of claim 4 wherein the tensile fuse translates two times the translation of the output shaft.

6. The decoupler of claim 4 , further comprising a blocking mechanism movable between an expanded position and a retracted position and configured to bar the output shaft from rethreading with the thread insert when in the retracted position.

7. An air turbine starter for starting an engine, comprising:
a housing defining an inlet, an outlet, and a flow path extending between the inlet and the outlet for communicating a flow of gas therethrough;
a turbine member journaled within the housing and disposed within the flow path for rotatably extracting mechanical power from the flow of gas;
a gear train drivingly coupled with the turbine member;
a clutch having a drive shaft operably coupled with the gear train; and
a decoupler, comprising:
a tensile fuse having a first end operably coupled to the drive shaft, a threaded portion, and a neck portion having a reduced diameter located between the first end and the threaded portion; and
an output shaft having a first end selectively operably coupled to the drive shaft, a second end configured to be operably coupled to and rotate with the engine, and an internal threaded portion that receives the threaded portion of the tensile fuse; and
wherein when a driving torque is transmitted from the drive shaft of the clutch to the output shaft the tensile fuse is not loaded, when an overrunning torque is transmitted below a certain level the tensile fuse is partially loaded and when the overrunning torque reaches a certain level the tensile fuse shears at the neck portion and the threaded portion of the tensile fuse is unwound from the internal threaded portion in a direction away from the drive shaft.

8. The air turbine starter of claim 7 , further comprising a thread insert operably coupled to the drive shaft and having a threaded portion that receives an exteriorly threaded portion of the first end of the output shaft.

9. The air turbine starter of claim 8 wherein the tensile fuse is threaded into the output shaft with an opposite hand turn to the threads between the output shaft and the thread insert.

10. The air turbine starter of claim 9 wherein when the overrunning torque reaches the certain level the output shaft is unthreaded from the thread insert such that the output shaft is uncoupled from the drive shaft when the tensile fuse is unwound from the output shaft.

11. The air turbine starter of claim 10 wherein the tensile fuse translates two times the translation of the output shaft.

12. The air turbine starter of claim 10 , further comprising a blocking mechanism movable between an expanded position and a retracted position and configured to bar the output shaft from rethreading with the thread insert when in the retracted position.

13. The air turbine starter of claim 12 wherein the blocking mechanism comprises a ring spring moveable between an expanded position where the ring spring is pushed outwards by the output shaft and a retracted position where the ring spring overlies a portion of the thread insert and is configured to prevent rethreading of the first end of the output shaft and the thread insert.

14. The air turbine starter of claim 13 , further comprising a retainer pin retaining the first end of the tensile fuse within the drive shaft.

15. The air turbine starter of claim 13 wherein the driving torque is transmitted through mating stop features on the drive shaft and the output shaft.

16. The air turbine starter of claim 10 , further comprising a biasing mechanism movable between a retracted position and an expanded position located between the drive shaft and the output shaft and configured to bias the output shaft away from the drive shaft when in the expanded position.

17. The air turbine starter of claim 16 , wherein the biasing mechanism is a compressive spring.

18. A method for operating a starter motor, comprising:
extracting mechanical power from a flow of gas utilizing a turbine and driving a gear train and clutch having a drive shaft therewith;
transmitting a driving torque from the drive shaft to an output shaft operably coupled to an engine; and
during back driving, activating a backdrive decoupler wherein a tensile fuse operably coupled to the output shaft and the drive shaft is sheared and a sheared portion of the tensile fuse is unwound from the output shaft and translated away from the drive shaft and the output shaft is unwound from the drive shaft and translated away from the drive shaft.

19. The method of claim 18 , wherein the tensile fuse translates two times the translation of the output shaft.

20. The method of claim 18 , further comprising preventing the output shaft from reengaging the drive shaft such that the starter motor is disabled after decoupling, which prevents an additional engine start.

Assignees

• Ge Aviation Systems Llc

Inventors

• Rodriguez Eliel Fresco
• Dranschak David Allan
• Meyers Shiloh Montegomery Emerson
• Bulathsinghalage Harsha Sanjeewa

Classifications

• F16D9/08

  over a single area encircling the axis of rotation, e.g. shear necks on shafts (F16D9/10 takes precedence) · CPC title

• F02C7/277 Primary

  the starter being a {separate} turbine · CPC title

• F02C7/32

  Arrangement, mounting, or driving, of auxiliaries · CPC title

• F02C7/268

  Starting drives for the rotor {, acting directly on the rotor of the gas turbine to be started} · CPC title

• F05D2220/32

  in gas turbines · CPC title