Sprag clutch assembly for aircraft drive wheel drive system

Patent metadata

Field	Value
Publication number	US-9302541-B2
Application number	US-201414158774-A
Country	US
Kind code	B2
Filing date	Jan 17, 2014
Priority date	Jan 17, 2014
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

A sprag clutch assembly for an aircraft drive wheel drive system capable of moving an aircraft autonomously on the ground in both forward and reverse directions is provided. The clutch is mounted within an aircraft drive wheel to be operatively engaged to control drive means braking torque when the aircraft is driven in a forward or reverse direction. The clutch assembly includes a plurality of pivoted sprag elements activatable to transmit torque and configured so that ratcheting occurs only when the aircraft drive wheel is driven in a forward direction and a braking torque is applied when the aircraft drive wheel is driven in reverse when the relative speed of the drive system is slower than the drive wheel speed, thereby permitting the drive system drive motor to function as a brake when the clutch assembly is engaged and the aircraft is reversing.

First claim

The invention claimed is:

1. A clutch assembly for an aircraft drive wheel drive system designed to control autonomous ground movement of an aircraft, comprising:
an aircraft drive wheel drive system mounted completely within an aircraft landing gear wheel and operatively connected to said landing gear wheel to control rotation of said wheel during autonomous ground travel, comprising a drive means in driving contact with and powering rotation of said wheel at a desired speed, torque, and direction of rotation, and a drive system in actuating contact with said drive means to actuate said drive means;
a clutch assembly in activating contact with said drive system and said drive means controllable to selectively engage and disengage said drive system into and out of actuating contact with said drive means, wherein said clutch assembly comprises a circumferential inner clutch element, a circumferential outer clutch element spaced outwardly of said inner clutch element in activating contact with said drive system, and a plurality of asymmetric engagement elements pivotable to selectively engage or disengage a corresponding plurality of pin elements to prevent or permit braking torque transmission between said inner clutch element and said outer clutch element; and
said plurality of engagement elements comprises a plurality of sprag elements configured with a radius of curvature to fit in a space between said inner clutch element and said outer clutch element and to pivot between an engaged position wherein each said sprag element is connected to a pin element to positively engage said outer clutch element and a disengaged position wherein said sprag element is disconnected from said pin element to disengage said outer clutch element; wherein each of said plurality of sprag elements is asymmetrically shaped to include a hook element at one circumferential extent and an angled fin at an opposite circumferential extent, and said hook element and said angled fin are positioned to extend outwardly along said inner clutch element from a central pivot holding said sprag element to said inner clutch element; and wherein said plurality of sprag elements are pivotally mounted on said inner clutch element so that a hook element of one sprag element contacts an angled fin of an adjacent sprag element, and each hook element and each fin includes an electrical contact positioned to contact an electrical contact on a hook element or a fin of an adjacent sprag element when said sprag elements are pivoted into engagement with said outer clutch element so that an electric circuit is completed when said sprag elements are in engaging contact with said outer clutch element and an electric current is supplied to said clutch assembly; and said clutch assembly further comprises a sensor located in electrical contact with at least one sprag element and in communication with a wheel drive system central controller.

2. The clutch assembly of claim 1 , wherein said outer clutch element comprises a plurality of engagement pins corresponding to said plurality of sprag elements, and each of said plurality of sprag elements includes a corresponding pin receptacle for receiving one of said plurality of engagement pins to positively engage said outer clutch element.

3. The clutch assembly of claim 2 , wherein said plurality of sprag elements is spaced circumferentially around said inner clutch element, and said sprag elements are mounted on said inner clutch element to pivot between a torque transmitting position wherein said pin receptacles engage said outer clutch element engagement pins and a torque transmission prevention position wherein said pin receptacles do not engage said outer clutch element engagement pins.

4. The clutch assembly of claim 3 , wherein said drive system comprises a roller traction drive assembly in actuating communication between said clutch assembly and said drive means.

5. The clutch assembly of claim 1 , wherein each of said plurality of sprag elements is sized and shaped to fit in an annular space between said inner clutch element and said outer clutch element and to pivot into and out of torque transmitting engagement with said outer clutch element or said aircraft wheel.

6. The clutch assembly of claim 1 , wherein said hook element comprises a pin receptacle shaped to engage a corresponding engagement pin on said clutch outer element or on said aircraft wheel.

7. The clutch assembly of claim 6 , wherein said pin receptacle comprises a curved receptacle or a slot-shaped receptacle, and said engagement pin is correspondingly shaped to ensure engagement with said curved receptacle or said slot-shaped receptacle.

8. The clutch assembly of claim 1 , wherein said outer clutch element is attached to said aircraft wheel and said plurality of sprag elements are positioned to transmit torque between said inner clutch element and said aircraft wheel.

9. The clutch assembly of claim 8 , wherein said engagement pins are located on said wheel, each said sprag element is configured to include a corresponding pin receptacle in said sprag hook element, and when said engagement pins are engaged by said pin receptacles to engage said inner clutch element and said wheel, said inner clutch element and said wheel are in torque transmission contact.

10. The clutch assembly of claim 9 , wherein when said engagement pins are engaged by said pin receptacles and said aircraft wheel is driven in a reverse direction by said drive means, said inner clutch element and said wheel are in braking torque transmission contact, and when said engagement pins are engaged by said pin receptacles and said aircraft wheel is driven in a forward direction, said inner clutch element and said wheel are in forward torque transmission contact.

11. The clutch assembly of claim 1 , further comprising a drag link ring element positioned between said inner and said outer clutch elements supporting said plurality of pin elements spaced on said drag link ring element to engage said plurality of engagement elements.

12. A method for selectively permitting or preventing operation of a drive means as a brake during aircraft ground travel using the clutch assembly of claim 1 , comprising causing said sprags to ratchet when said engagement pins are engaged in pin receptacles in said hook elements, so that when said aircraft is driven in a forward direction by said drive system drive means, torque is applied in a forward direction and when said aircraft is driven in a reverse direction by said drive system drive means, braking torque is applied to said system.

Assignees

• Borealis Tech Ltd

Inventors

• Edelson Jonathan Sidney

Classifications

• B64C25/405 Primary

  Powered wheels, e.g. for taxing · CPC title

• B60B25/12

  with integral flange part · CPC title

• F16D41/14

  the effective stroke of the pawl being adjustable · CPC title

• B60B27/0021 Primary

  characterised by torque transmission means from drive axle · CPC title

• B60Y2200/51

  Aeroplanes · CPC title