Washing machine and coupling apparatus

1. A coupling apparatus comprising:

an inner shaft rotatably driven about a longitudinal axis of rotation, said inner shaft comprising a plurality of inner shaft external splines;

an outer shaft concentric with said inner shaft for selective rotation about said longitudinal axis, said outer shaft configured to be rotatably driven by said inner shaft with said outer shaft engaged with said inner shaft, said outer shaft comprising a plurality of outer shaft external splines;

a coupler movable along a length of said inner shaft with respect to the longitudinal axis between a first position engaging said outer shaft to said inner shaft for rotation therewith, and a second position disengaging said outer shaft from said inner shaft for relative rotation therebetween, said coupler comprising a plurality of first splines engaging said plurality of inner shaft external splines and a plurality of second splines engaging said plurality of outer shaft external splines in said first position; and

an actuator positioned to move said coupler between said first position and said second position.

2. A coupling apparatus in accordance with claim 1 , wherein said coupling is movable to a third position wherein said coupling is not engaged to either of said inner and outer shafts.

3. A coupling apparatus in accordance with claim 1 , wherein said coupler is concentric with said inner shaft and said outer shaft.

4. A coupling apparatus in accordance with claim 1 , wherein said actuator comprises a biasing member biasing said coupler toward one of said first and second positions.

5. A coupling apparatus in accordance with claim 1 , further comprising a brake to lock said outer shaft in a stationary position.

6. A coupling apparatus in accordance with claim 1 , wherein said coupler is in continuous engagement with said inner shaft.

7. A coupling apparatus in accordance with claim 1 , wherein said coupler is in continuous engagement with said outer shaft.

8. A coupling apparatus in accordance with claim 1 , wherein one of said inner shaft and said outer shaft includes a hub connected thereto, said hub comprising a flange having drive teeth about a periphery thereof and said coupler is splined to the other of said inner shaft and said outer shaft and comprises a rim having drive teeth configured for engagement with said drive teeth on said flange.

9. A coupling apparatus in accordance with claim 1 , wherein said coupler comprises a magnetic fluid disposed within a space between said inner shaft and said outer shaft and said actuator comprises an electromagnet configured to increase a viscosity of said magnetic fluid when said electromagnet is energized.

10. A coupling apparatus in accordance with claim 9 , wherein said inner shaft includes splines on a periphery thereof configured to engage said magnetic fluid when said electromagnet is energized to drive said outer shaft.

11. A coupling apparatus in accordance with claim 1 , wherein said actuator comprises a lever configured for engagement with said coupler.

12. A coupling apparatus in accordance with claim 1 , wherein said actuator comprises at least one of a solenoid, an electric motor, a spring, and a wax motor.

13. A coupling apparatus in accordance with claim 1 , wherein said actuator is hydraulically driven.

14. A coupling apparatus in accordance with claim 1 , wherein said actuator is pneumatically driven.

15. A washing machine comprising:

a wash tub;

a perforated basket rotatably mounted within said tub;

an agitation element disposed within said basket to agitate at least one article within said basket;

an outer shaft selectively rotatable about a longitudinal axis and connected to said basket to drive said basket, said outer shaft comprising a plurality of outer shaft external splines on a periphery of said outer shaft;

an inner shaft coaxially aligned with said outer shaft and connected to said agitation element to drive said agitation element, said inner shaft configured to rotatably drive said outer shaft when said inner shaft is engaged with said outer shaft, said inner shaft comprising a plurality of inner shaft external splines;

a motor drivingly connected to said inner shaft; and

a coupling mechanism to selectively couple said inner shaft and said outer shaft, said coupling mechanism comprising:

a coupler movable along a length of said inner shaft with respect to the longitudinal axis between a first position engaging said outer shaft to said inner shaft for rotation therewith, and a second position disengaging said outer shaft from said inner shaft for relative rotation therebetween, said coupler comprising a plurality of first splines engaging said plurality of inner shaft external splines and a plurality of second splines engaging said plurality of outer shaft external splines in said first position; and

an actuator positioned to move said coupler between said first position and said second position.

16. A washing machine in accordance with claim 15 , wherein said inner shaft is disposed within said outer shaft, said inner shaft and outer shaft having a common axis of rotation.

17. A washing machine in accordance with claim 16 , wherein said coupler is concentric with said outer shaft and said inner shaft.

18. A washing machine in accordance with claim 15 , wherein said coupling mechanism further comprises a biasing member biasing said coupler toward one of said first and second positions.

19. A washing machine in accordance with claim 15 , wherein said coupling mechanism further comprises a brake to lock said outer shaft in a stationary position.