Hydrokinetic torque coupling device having turbine-piston lockup clutch, and related methods

1. A hydrokinetic torque coupling device for coupling together a driving shaft and a driven shaft, the torque coupling device comprising:

an impeller rotatable about a rotational axis and comprising an impeller shell;

a casing comprising the impeller shell and a casing shell fixedly connected thereto so as to be non-rotatable relative to the impeller shell, the casing having a first engagement surface;

a turbine-piston hydrodynamically drivable by the impeller and comprising a turbine-piston shell having a second engagement surface facing the first engagement surface, the turbine-piston being axially displaceable relative to the impeller between a hydrodynamic transmission mode in which the first and second engagement surfaces are spaced from and not frictionally engaged with one another, and a lockup mode in which the first and second engagement surfaces are frictionally engaged with one another to mechanically lock the turbine-piston with the casing so as to be non-rotatable relative to the casing; and

a biasing device configured to exert an axial load against the turbine-piston to urge the turbine-piston axially away from the lockup mode and towards the hydrodynamic transmission mode, wherein the axial load exerted by the biasing device decreases as the turbine-piston moves axially towards the lockup mode and increases as the turbine-piston moves axially away from the lockup mode.

2. The hydrokinetic torque coupling device of claim 1 , wherein the biasing device exerts a nonlinear load against the turbine-piston to urge the turbine-piston axially away from the lockup mode and towards the hydrodynamic transmission mode, wherein the nonlinear load exerted by the biasing device is not proportional to displacement of the turbine-piston between the lockup mode and the hydrodynamic transmission mode.

3. The hydrokinetic torque coupling device of claim 1 , further comprising a stator situated between the impeller and the turbine-piston.

4. The hydrokinetic torque coupling device of claim 3 , wherein the biasing device is situated between the stator and the turbine-piston shell.

5. The hydrokinetic torque coupling device of claim 4 , wherein the biasing device is part of a biasing and bearing device which comprises:

a stator-side retainer member connected to and non-rotatable relative to the stator;

a turbine-side retainer member connected to and non-rotatable relative to the turbine-piston; and

the biasing device situated between the stator-side retainer member and the turbine-side retainer member.

6. The hydrokinetic torque coupling device of claim 5 , wherein the biasing device is rotatable relative to one of the turbine-side retainer member and the stator-side retainer member and fixedly connected to the other of the turbine-side retainer member and the stator-side retainer member.

7. The hydrokinetic torque coupling device of claim 5 , wherein the biasing device is rotatable relative to at least one of the turbine-side retainer member and the stator-side retainer member.

8. The hydrokinetic torque coupling device of claim 5 , wherein the turbine-side retainer member is mounted on the turbine-piston shell.

9. The hydrokinetic torque coupling device of claim 1 , wherein the biasing device comprises a diaphragm spring.

10. The hydrokinetic torque coupling device of claim 1 , wherein the biasing device comprises a Belleville washer.

11. The hydrokinetic torque coupling device of claim 10 , wherein the Belleville washer is fixedly connected to the turbine-piston shell.

12. The hydrokinetic torque coupling device of claim 11 , wherein the biasing device further comprises a thrust washer connected to and non-rotatable relative to the stator, the thrust washer contacting and being rotatable relative to the Belleville washer.

13. The hydrokinetic torque coupling device of claim 1 , wherein the biasing device comprises a bayonet connector.

14. The hydrokinetic torque coupling device of claim 13 , wherein the bayonet connector comprises first and second bayonet housing members and at least one Belleville spring housed between the first and second bayonet housing members.

15. The hydrokinetic torque coupling device of claim 1 , wherein the first engagement surface or the second engagement surface comprises a frictional lining.

16. The hydrokinetic torque coupling device of claim 1 , wherein the turbine-piston shell further comprises a radially extending flange defining the second engagement surface.

17. A hydrokinetic torque coupling device for coupling together a driving shaft and a driven shaft, the torque coupling device comprising:

an impeller rotatable about a rotational axis and comprising an impeller shell;

a casing comprising the impeller shell and a casing shell fixedly connected to so as to be non-rotatable relative to the impeller shell, the casing having a first engagement surface;

a turbine-piston hydrodynamically drivable by the impeller and comprising a turbine-piston shell having a second engagement surface facing the first engagement surface, the turbine-piston being axially displaceable relative to the impeller between a hydrodynamic transmission mode in which the first and second engagement surfaces are spaced from and not frictionally engaged with one another, and a lockup mode in which the first and second engagement surfaces are frictionally engaged with one another to mechanically lock the turbine-piston with the casing so as to be non-rotatable relative to the casing;

a stator situated between the impeller and the turbine-piston;

a biasing device configured to exert an axial load against the turbine-piston to urge the turbine-piston axially away from the lockup mode and towards the hydrodynamic transmission mode, wherein the axial load exerted by the biasing device decreases as the turbine-piston moves axially towards the lockup mode and increases as the turbine-piston moves axially away from the lockup mode;

an output hub; and

a damper assembly interconnecting the turbine-piston to the output hub.

18. The hydrokinetic torque coupling device of claim 17 , further comprising a drive member interconnecting the turbine-piston shell to the damper assembly, wherein the damper assembly comprises an intermediate member, a first set of circumferentially extending elastic damping members drivingly coupling the drive member to the intermediate member, a driven member connected to and non-rotatable relative to the output hub, a second set of circumferentially extending elastic damping members drivingly coupling the intermediate member to the driven member, and a centrifugal pendulum oscillator mounted to the intermediate member.

19. The hydrokinetic torque coupling device of claim 17 , further comprising a drive member interconnecting the turbine-piston shell to the damper assembly, wherein the damper assembly comprises an intermediate member, a first set of circumferentially extending elastic damping members drivingly coupling the drive member to the intermediate member, a driven member connected to and non-rotatable relative to the output hub, a second set of circumferentially extending elastic damping members drivingly coupling the intermediate member to the driven member, and a spring mass system coupled to the intermediate member.

20. A method of assembling a hydrokinetic torque coupling device for coupling a driving shaft and a driven shaft together, comprising:

providing a torque converter rotatable about a rotational axis and comprising

an impeller comprising an impeller shell;

a turbine-piston hydrodynamically drivable by the impeller and comprising a turbine-piston shell; and

a biasing device; and

operatively connecting a casing shell to the impeller shell of the torque converter to form a casing that is rotatable about the rotational axis and has a first engagement surface, the turbine-piston having a second engagement surface and being axially displaceable relative to the impeller between a hydrodynamic transmission mode in which the first and second engagement surfaces are spaced from and not frictionally engaged with one another, and a lockup mode in which the first and second engagement surfaces are frictionally engaged with one another to mechanically lock the turbine-piston with the casing so as to be non-rotatable relative to the casing,

wherein the biasing device is configured to exert an axial load against the turbine-piston to urge the turbine-piston axially away from the lockup mode and towards the hydrodynamic transmission mode, wherein the axial load exerted by the biasing device decreases as the turbine-piston moves axially towards the lockup mode and increases as the turbine-piston moves axially towards the hydrodynamic transmission mode.