CONTROL OF TRANSMISSION WITH ACTIVATED POWER TAKE-OFF
A method and system for operating a powertrain that includes a transmission with two power take-off outputs and transmission output shaft is described. In one example, the powertrain is operated in a speed control mode whereby vehicle speed is controlled so that powertrain control may be simplified when a vehicle is moving and a power take-off is supplying power to an external device.
1 . A powertrain, comprising:
a transmission including a power take-off and an output shaft that delivers torque to vehicle wheels, where the power take-off is coupled to the output shaft via a planetary gear set; and
a controller including executable instructions that cause the controller to operate the powertrain in a first speed control mode where an output shaft rotational speed is controlled via the controller in response to a vehicle that includes the powertrain traveling with rotating wheels while delivering power to the power take-off.
2 . The powertrain of claim 1 , further comprising operating the power take-off in a second speed control mode while operating the powertrain in the first speed control mode.
3 . The powertrain of claim 2 , where a first speed controller of the controller controls the output shaft rotational speed, and where a second speed controller of the controller controls a power take-off rotational speed.
4 . The powertrain of claim 3 , where the first speed controller controls the output shaft rotational speed to a first rotational speed, where the second speed controller controls the power take-off rotational speed to a second rotational speed, and where the second rotational speed is different than the first rotational speed.
5 . The powertrain of claim 4 , where the first speed controller adjusts torque of a propulsion source in response to a difference between a requested vehicle speed and an actual vehicle speed.
6 . The powertrain of claim 5 , where the requested vehicle speed is based on a position of a driver demand pedal.
7 . The powertrain of claim 1 , where a second speed controller adjusts torque of an electric machine in response to a difference between a requested power take-off speed and an actual power take-off speed.
8 . A method for operating a powertrain, comprising:
operating the powertrain in a speed control mode where a speed of a vehicle speed is controlled to a requested vehicle speed via a controller and in response to a power take-off supplying power to a device external to a transmission and a vehicle that includes the transmission traveling with rotating wheels.
9 . The method for operating the powertrain of claim 8 , where the speed control mode includes adjusting the speed of the vehicle to the requested vehicle speed while torque supplied via the powertrain is varied.
10 . The method for operating the powertrain of claim 9 , further comprising torque supplied via the powertrain in response to a difference between the requested vehicle speed and the vehicle speed.
11 . The method for operating the powertrain of claim 10 , where the controller is a proportional, integral, derivative controller.
12 . The method for operating the powertrain of claim 11 , further comprising operating the power take-off in a second speed control mode via a second controller.
13 . The method for operating the powertrain of claim 12 , where the second controller is a proportional/integral/derivative controller.
14 . The method for operating the powertrain of claim 8 , where operating the powertrain in the speed control mode includes adjusting a wheel torque output of the powertrain, and further comprising:
confining the wheel torque output to be between a first threshold torque and a second threshold torque.
15 . The method for operating the powertrain of claim 14 , where the first threshold torque and the second threshold torque vary with the vehicle speed.
16 . A powertrain, comprising:
a transmission including a first power take-off port including a power take-off shaft that rotates at a multiple of a rotational rate of a first shaft, the first shaft coupled to a ring gear of first planetary gear set, a second shaft configured to deliver power to vehicle wheels, the second shaft coupled to carrier planetary gears of the first planetary gear set; and a second power take-off port, the second power take-off port coupled to a sun gear of the first planetary gear set, the first power take-off port and the second power take-off port not configured to be coupled to the second shaft, except via the first planetary gear set; and
a controller including executable instructions that cause the controller to operate the powertrain in a speed control mode in response to a vehicle that includes the powertrain traveling with rotating wheels while delivering power to the second power take-off port.
17 . The powertrain of claim 16 , where the speed control mode includes controlling a vehicle speed, and further comprising:
additional instructions to control the vehicle speed via vehicle speed feedback.
18 . The powertrain of claim 17 , further comprising additional instructions to control the vehicle speed in response to a requested vehicle speed, and where the requested vehicle speed is based on a position of a driver demand pedal.
19 . The powertrain of claim 16 , further comprising additional instructions to control a speed of a shaft of the second power take-off port.
20 . The powertrain of claim 16 , further comprising additional instructions to confine wheel torque output to be between a first threshold wheel torque and a second threshold wheel torque.