Vehicle transmission with clutch pack overrun

1. A transmission system, comprising:

an input shaft;

a first clutch configured to selectively couple a first gear to the input shaft;

an output shaft;

a second gear engaging with the first gear; and

a second clutch configured to selectively couple the second gear to the output shaft when the first gear rotates the second gear, wherein a reduction in transmission gear engagement shock is provided by increasing an amount of pressure applied to the first clutch so that the first clutch transitions from a gear slip state, in which only a partial amount of vehicle torque is transmitted from the input shaft to the first gear, to a locked state, in which the first gear is fully locked to the input shaft.

2. The transmission system according to claim 1 wherein the second clutch is configured to release the second gear from the output shaft when the output shaft rotates faster than the second gear.

3. The transmission system according to claim 1 further comprising:

a third clutch configured to selectively couple a third gear to the input shaft;

a fourth gear engaging with the third gear; and

a fourth clutch configured to couple the fourth gear to the output shaft, wherein during a vehicle upshift an increasing amount of pressure is applied to the third clutch so that the third clutch transitions from a gear slip state to a locked state while keeping the first clutch in the locked state, in which the second gear is no longer coupled to the output shaft.

4. The transmission system according to claim 3 wherein the fourth gear is configured to rotate faster than the second gear and cause the output shaft to free wheel inside of the second gear when the fourth gear is coupled to the output shaft.

5. The transmission system according to claim 4 further comprising:

a fifth gear rigidly coupled to the input shaft;

a sixth gear engaging with the fifth gear; and

a fifth clutch configured to selectively couple the fifth gear to the output shaft.

6. The transmission system according to claim 5 wherein the sixth gear is configured to rotate faster than the second gear and rotate faster than the fourth gear and cause the output shaft to free wheel inside of the second gear and free wheel inside of the fourth gear when the sixth gear is coupled to the output shaft.

7. The transmission system according to claim 5 wherein:

a gear ratio of the fourth and third gear is smaller than a gear ratio of the second and first gear; and

a gear ratio of the sixth and fifth gear is smaller than the gear ratio between the fourth and third gear.

8. The transmission system according to claim 5 wherein the first, third and fifth clutches are hydraulic clutches and the second and fourth clutches are one-way bearings.

9. The transmission system according to claim 1 wherein the input shaft is coupled to a vehicle engine without an intermediate torque converter and the output shaft is coupled to a drive axle assembly.

10. A vehicle, comprising:

an engine;

a drive axle; and

a transmission system coupled between the engine and the drive axle and including mechanisms configured to enable associated gears to supply torque to the drive axle, wherein the mechanisms enable the associated gears to transfer torque to the drive axle when the associated gears rotate faster than at least some of the other gears and disable the associated gears from transferring torque to the drive axle when at least one of the other gears rotate faster than the associated gears, and wherein a reduction in transmission gear engagement shock is provided by increasing an amount of pressure applied to a clutch so that the clutch transitions from a gear slip state, in which only a partial amount of vehicle torque is transmitted from an input shaft to a drive gear, to a locked state, in which the drive gear is fully locked to the input shaft.

11. The vehicle according to claim 10 wherein a set of hydraulic clutches are activated by a processor according to a desired vehicle speed and the mechanisms are activated according to a rotational speed of the associated gears.

12. The vehicle according to claim 11 wherein the transmission system further comprises a first shaft coupled to the engine and a second shaft coupled to the drive axle, and at least some of the hydraulic clutches are located on the first shaft and at least some of the mechanisms are located on the second shaft.

13. The vehicle according to claim 12 wherein:

drive gears on the first shaft are configured to engage with driven gears on the second shaft;

at least some of the hydraulic clutches couple the drive gears to the first shaft; and

at least some of the mechanisms couple the driven gears to the second shaft.

14. The vehicle according to claim 13 wherein at least one of the hydraulic clutches couple at least one of the driven gears to the second shaft.

15. The vehicle according to claim 11 wherein the mechanisms comprise one-way bearings.

16. A vehicle control system, comprising: a processor configured to:

actuate a first clutch to enable a first drive gear to apply torque to a vehicle; and

actuate a second clutch to enable a second drive gear to apply torque to the vehicle, wherein enabling the second drive gear disables the first drive gear from applying torque to the vehicle, and wherein a reduction in transmission gear engagement shock is provided by increasing an amount of pressure applied to the second clutch so that the second clutch transitions from a gear slip state, in which only a partial amount of vehicle torque is transmitted from an input shaft to the second drive gear, to a locked state, in which the second drive gear is fully locked to the input shaft.

17. The vehicle control system according to claim 16 wherein actuating the first clutch and deactuating the second clutch cause the first drive gear to start rotating a first driven gear and lock the first driven gear to an output shaft.

18. The vehicle control system according to claim 17 wherein actuating the second clutch causes the second drive gear to start rotating a second driven gear faster than the first drive gear rotates the first driven gear and unlock the first driven gear from the output shaft.

19. The vehicle control system according to claim 16 wherein the processor is further configured to:

slip the first clutch to initially start moving the vehicle;

lock the first clutch when a first vehicle speed signal is detected;

engage the second clutch when a second vehicle speed signal is detected, wherein engaging the second clutch disables the first drive gear from applying torque to the vehicle; and

engage a third clutch when a third vehicle speed signal is detected, wherein engaging the third clutch disables the first drive gear and second drive gear from applying torque to the vehicle.

20. The vehicle control system according to claim 16 wherein the processor is further configured to:

slip the first clutch to initially start moving the vehicle;

engage directional clutches in the drive axle of the vehicle to control what direction the vehicle moves; and

lock the first clutch after the vehicle reaches a first vehicle speed.

21. The vehicle control system according to claim 16 wherein the processor is further configured to:

increase pressure in the first clutch responsive to a move command;

apply a locking pressure to the first clutch when slip in the first clutch reaches zero; and

reduce the locking pressure to the first clutch when an engine speed falls below a first downshift speed value and then vary the pressure in the first clutch according to vehicle parameters.

22. The vehicle control system according to claim 21 wherein the processor is further configured to:

increase pressure in the second clutch when the engine speed rises above a first upshift speed value;

apply a locking pressure to the second clutch when slip in the second clutch reaches zero; and

reduce the locking pressure to the second clutch when an engine speed falls below a second downshift speed value and then vary the pressure in the first clutch according to the vehicle parameters.

23. The vehicle control system according to claim 22 wherein the processor is further configured to:

increase pressure in a third clutch when the engine speed rises above a second upshift speed value;

apply a locking pressure to the third clutch when slip in the third clutch reaches zero; and

reduce the locking pressure to the third clutch when an engine speed falls below a third downshift speed value and vary the pressure in the second clutch according to the vehicle parameters.