Four-passage multifunction torque converter

1. A torque converter comprising:

an impeller clutch arranged to transmit, when closed, torque from a first cover for the torque converter to a shell for an impeller;

a lock-up clutch arranged to transmit, when closed, torque from a second cover for the torque converter to an output hub;

a release chamber for the impeller clutch, connected to a first channel;

an apply chamber for the impeller clutch, connected to a second channel;

an apply chamber for the lock-up clutch, connected to a third channel; and,

a torus connected to a fourth channel, wherein the second, third, and fourth channels open to a space including a longitudinal axis for the torque converter, wherein the space is arranged to receive an input shaft for a transmission, wherein the first channel is arranged to connect to a line in a pump housing for a transmission, wherein the torque converter is arranged to rotationally connect to a pump for the transmission and wherein the line in the pump housing leads to a sump for the transmission.

2. The torque converter of claim 1 wherein the second and fourth channels form a portion of a fluid circuit through the torus, the circuit bypassing the impeller clutch.

3. The torque converter of claim 1 wherein fluid flows out of the release chamber through the first channel as the impeller clutch is closing.

4. The torque converter of claim 1 further comprising an elastically deformable element urging the impeller shell away from the cover.

5. The torque converter of claim 4 wherein the impeller clutch is arranged to open in response to the urging of the elastically deformable element and a reduction in the flow rate for cooling oil flowing through the torus.

6. The torque converter of claim 1 wherein the apply chamber for the lock-up clutch is sealed with the exception of the third channel.

7. The torque converter of claim 1 further comprising a release chamber for the lock-up clutch in fluid communication with the apply chamber for the impeller clutch.

8. A method of operating an impeller clutch in a torque converter comprising the steps of:

flowing fluid, from an oil cooler, between first and second channels in the torque converter and through a torus for the torque converter, the first and second channels opening to an apply chamber for the impeller clutch and the torus, respectively;

bypassing the impeller clutch with the flowing fluid;

venting fluid from a release chamber for the impeller clutch through a line in a pump housing for a transmission; and,

closing the impeller clutch.

9. The method of claim 8 further comprising the step of transmitting torque from a cover for the torque converter through the impeller clutch to a shell for an impeller.

10. The method of claim 8 wherein the line in the pump housing leads to a sump for the transmission.

11. The method of claim 8 further comprising the steps of:

applying a force, using an elastically deformable element, on the impeller clutch;

reducing the flow of fluid through the torus; and,

opening the impeller clutch.