Friction assisted dog clutch

1. A clutch assembly, comprising:

a piston;

one or more pins, wherein the one or more pins are adapted to be moved by a hydraulic pressure;

one or more friction discs, wherein the one or more friction discs have a number of slots and the one or more pins pass through the slots; and

an endplate, wherein the endplate has a number of recesses adapted to receive the one or more pins, wherein at least one of:

the number of slots is less than a number of pins;

the one or more friction discs are mechanically coupled to a clutch gear and the endplate is mechanically coupled to a shaft via a clutch drum;

the clutch assembly further comprises one or more piston return springs adapted to be compressed when the piston is moved towards the endplate; and

the clutch assembly further comprises one or more pin return springs adapted to be compressed when the one or more pins are moved towards the endplate.

2. The clutch assembly of claim 1 , wherein the number of recesses is equivalent to a number of pins.

3. The clutch assembly of claim 1 , wherein the piston is adapted to be actuated by the hydraulic pressure.

4. The clutch assembly of claim 1 , wherein contact between the piston and the one or more friction discs synchronizes rotation of a clutch gear and a shaft.

5. The clutch assembly of claim 1 , wherein the one or more pins extending through the slots and at least partially through openings of the recesses mechanically locks rotation of a clutch gear and a shaft, such that torque is transferred between the clutch gear and shaft.

6. A method, comprising:

in response to a request to engage a friction assisted dog clutch, moving a piston of the friction assisted dog clutch towards a friction disc of the friction assisted dog clutch;

synchronizing rotation of a clutch gear and a shaft of the friction assisted dog clutch;

moving a pin of the friction assisted dog clutch through a slot of the friction disc with the pin unlocked from an endplate of the friction assisted dog clutch; and

locking the pin with the endplate of the friction assisted dog clutch.

7. The method of claim 6 , wherein the method further comprises:

in response to a request to disengage the friction assisted dog clutch, unlocking the pin with the endplate of the friction assisted dog clutch;

moving the pin out of the slot of the friction disc; and

moving the piston away from the friction disc.

8. The method of claim 7 , wherein each of moving the piston towards the friction disc, moving the pin through the slot of the friction disc, moving the pin out of the slot of the friction disc, and moving the position away from the friction disc comprises actuating movement of the pin and the piston by hydraulic pressure.

9. The method of claim 8 , wherein synchronizing rotation includes pressing the piston against the friction disc.

10. The method of claim 9 , wherein locking the pin with the endplate includes the pin extending at least partially through an opening of a recess of the endplate.

11. The method of claim 10 , wherein the request to engage the friction assisted dog clutch is initiated by a controller communicatively coupled to the friction assisted dog clutch in response to a signal from a sensor fluidly coupled to an interior of the friction assisted dog clutch.

12. A transmission, comprising:

a friction assisted dog clutch, wherein the friction assisted dog clutch includes a piston coupled to a piston return spring, a pin coupled to a pin return spring, one or more friction discs, and an endplate including a recess adapted to receive the pin, each of the piston and the pin being adapted to be moved axially by a hydraulic pressure, and each of the one or more friction discs including a slot; and

a controller including instructions stored on non-volatile memory, the instructions executable to:

in response to a request to engage the friction assisted dog clutch,

apply a first pressure to the piston, the first pressure greater than a first threshold pressure and less than a second threshold pressure, the first pressure adapted to compress the piston return spring; and

apply a second pressure to the piston, the second pressure greater than the second threshold pressure and adapted to compress the pin return spring.

13. The transmission of claim 12 , wherein the instructions of the controller are further executable to:

in response to a request to disengage the friction assisted dog clutch,

apply a third pressure to the piston, the third pressure greater than the first threshold pressure and less than the second threshold pressure, the third pressure adapted to extend the pin return spring; and

apply a fourth pressure to the piston, the fourth pressure less than the first threshold pressure, the fourth pressure adapted to extend the piston return spring.

14. The transmission of claim 12 , wherein the friction assisted dog clutch is a wet clutch.

15. The transmission of claim 12 , wherein applying the first pressure synchronizes rotation of the piston and friction disc such that up to a first torque is transferred therebetween.

16. The transmission of claim 15 , wherein applying the second pressure locks the piston and friction disc such that up to a second torque, the second torque being higher than the first torque, is transferred therebetween.