High efficiency, high output transmission
A transmission includes an input shaft coupled to a prime mover, a countershaft, main shaft, and an output shaft, with gears between the countershaft and the main shaft. A shift actuator selectively couples the input shaft to the main shaft by rotatably coupling gears between the countershaft and the main shaft. The shift actuator is mounted on an exterior wall of a housing including the countershaft and the main shaft. An integrated actuator housing includes a single external power access for the shift actuator. A controller interprets a shaft displacement angle, determines if the transmission is in an imminent zero or zero torque region, and performs a transmission operation in response to the transmission in the imminent zero or zero torque region.
1. A computer product in a non-transitory memory for controlling a vehicle, wherein the computer product configures a processor when implemented from the memory to:
provide a friction brake engagement command; wherein a transmission of the vehicle comprises a friction brake responsive to the friction brake engagement command to engage a countershaft of the transmission;
track an engaged time of the friction brake;
determine a target release time for the friction brake;
determine a release delay for the friction brake in response to the engaged time; and
command a release of the friction brake in response to the release delay and the target release time.
2. The computer product of claim 1 , wherein the processor is further configured to determine the release delay by determining a pressure and a pressure decay value in a friction brake actuation volume; and wherein determining the pressure decay value includes utilizing a pre-determined relationship between the engaged time and pressure decay in the friction brake actuation volume.
3. The computer product of claim 1 , wherein the processor is further configured to determine a speed differential between the countershaft and an engaging shaft, and to determine the target release time based at least in part on the speed differential.
4. The computer product of claim 3 , wherein the engaging shaft includes at least one shaft comprising an output shaft, a main shaft, and an input shaft.
5. The computer product of claim 1 , wherein the processor is further configured to determine a lumped driveline stiffness value, and to determine the target release time based at least in part on the lumped driveline stiffness value.
6. The computer product of claim 1 , wherein the processor is further configured to determine a target gear ratio value, and to determine the target release time based at least in part on the target gear ratio value.
7. The computer product of claim 1 , wherein the processor is further configured to determine a friction brake disengagement dynamic value, and to determine the target release time based at least in part on the friction brake disengagement dynamic value.
8. The computer product of claim 1 , wherein the processor is further configured to determine a vehicle speed effect, and to determine the target release time based at least in part on the vehicle speed effect;
wherein the vehicle speed effect includes at least one effect comprising:
a current vehicle speed;
an estimated vehicle speed at a gear engagement time;
a vehicle acceleration rate; and
a vehicle deceleration rate.
9. A method of operating a vehicle transmission friction brake for controlling a vehicle, comprising:
providing a friction brake engagement command; wherein a transmission of the vehicle comprises a friction brake responsive to the friction brake engagement command to engage a countershaft of the transmission;
tracking an engaged time of the friction brake;
determining a target release time for the friction brake;
determining a release delay for the friction brake in response to the engaged time; and
commanding a release of the friction brake in response to the release delay and the target release time.
10. The method of claim 9 , further comprising determining the release delay by determining a pressure and a pressure decay value in a friction brake actuation volume; and wherein determining the pressure decay value includes utilizing a pre-determined relationship between the engaged time and pressure decay in the friction brake actuation volume.
11. The method of claim 9 , further comprising determining a speed differential between the countershaft and an engaging shaft, and determining the target release time based at least in part on the speed differential.
12. The method of claim 11 , wherein the engaging shaft includes at least one shaft comprising an output shaft, a main shaft, and an input shaft.
13. The method of claim 9 , further comprising determining a lumped driveline stiffness value, and determining the target release time based at least in part on the lumped driveline stiffness value.
14. The method of claim 9 , further comprising determining a target gear ratio value, and determining the target release time based at least in part on the target gear ratio value.
15. The method of claim 9 , further comprising determining a friction brake disengagement dynamic value, and determining the target release time based at least in part on the friction brake disengagement dynamic value.
16. The method of claim 9 , further comprising determining a vehicle speed effect, and determining the target release time based at least in part on the vehicle speed effect;
wherein the vehicle speed effect includes at least one effect comprising:
a current vehicle speed;
an estimated vehicle speed at a gear engagement time;
a vehicle acceleration rate; and
a vehicle deceleration rate.
17. A vehicle control system comprising:
a transmission that has a friction brake; and
a control unit that:
provides a friction brake engagement command; wherein the friction brake is responsive to the friction brake engagement command to engage a countershaft of the transmission;
tracks an engaged time of the friction brake;
determines a target release time for the friction brake;
determines a release delay for the friction brake in response to the engaged time; and
commands a release of the friction brake in response to the release delay and the target release time.
18. The vehicle control system of claim 17 , wherein the control unit further:
determines the release delay by determining a pressure and a pressure decay value in a friction brake actuation volume, wherein determining the pressure decay value includes utilizing a pre-determined relationship between the engaged time and pressure decay in the friction brake actuation volume; and
determines a speed differential between the countershaft and an engaging shaft, and determines the target release time based at least in part on the speed differential, wherein the engaging shaft includes at least one shaft comprising an output shaft, a main shaft, and an input shaft.
19. The vehicle control system of claim 17 , wherein the control unit further:
determines a lumped driveline stiffness value, and determines the target release time based at least in part on the lumped driveline stiffness value; and
determines a target gear ratio value, and determines the target release time based at least in part on the target gear ratio value.
20. The vehicle control system of claim 17 , wherein the control unit further:
determines a friction brake disengagement dynamic value, and determines the target release time based at least in part on the friction brake disengagement dynamic value; and
determines a vehicle speed effect, and determines the target release time based at least in part on the vehicle speed effect;
wherein the vehicle speed effect includes at least one effect comprising:
a current vehicle speed;
an estimated vehicle speed at a gear engagement time;
a vehicle acceleration rate; and
a vehicle deceleration rate.