Transmission shifting system and method
Methods and systems for adjusting operation of a dog clutch actuator are shown. The systems and methods may base dog clutch actuator adjustment on a roll-off time that describes when reduction of propulsion source torque has produced a corresponding reduction in dog clutch torque that will allow the dog clutch to be disengaged with minimal effort.
1 . A method for operating a transmission, comprising:
commanding a reduction in electric machine torque; and
commanding a dog clutch actuator from a first position where a dog clutch is engaged via the dog clutch actuator to a second position where the dog clutch is disengaged via the dog clutch actuator responsive to a predetermined amount of time since commanding the reduction in electric machine torque, where the predetermined amount of time is based on a transfer function.
2 . The method for operating the transmission of claim 1 , where the second position where the dog clutch is disengaged is a neutral position.
3 . The method for operating the transmission of claim 1 , where the predetermined amount of time is based on data captured during a step change in electric machine torque.
4 . The method for operating the transmission of claim 3 , where the step change in electric machine torque reduces electric machine electric torque.
5 . The method for operating the transmission of claim 3 , where the transfer function is estimated from the data captured during the step change in electric machine torque.
6 . The method for operating the transmission of claim 5 , where the predetermined amount of time is further based on a function to minimize transmission input torque that considers constraints to facilitate dog clutch disengagement.
7 . The method for operating the transmission of claim 6 , where the predetermined amount of time is determined via a simulation.
8 . The method for operating the transmission of claim 1 , further comprising storing the predetermined amount of time to controller memory.
9 . A propulsion system, comprising:
a transmission including a dog clutch;
a propulsion source coupled to the transmission;
a controller including executable instructions stored in non-transitory memory that cause the controller to disengage the dog clutch from a gear in response to an amount of time since a reduction in torque of the propulsion source, the reduction in torque of the propulsion source based on a gear shift request, where the amount of time is based on an estimated transfer function.
10 . The propulsion system of claim 9 , further comprising a first layshaft, the dog clutch coupled to the first layshaft.
11 . The propulsion system of claim 10 , further comprising additional executable instructions that cause the controller to determine the amount of time according to vehicle operating conditions.
12 . The propulsion system of claim 11 , where the vehicle operating conditions include vehicle speed and driver demand torque or power.
13 . The propulsion system of claim 12 , where the vehicle operating conditions also include vehicle mass.
14 . The propulsion system of claim 9 , where the amount of time is based on a minimization function.
15 . A method for operating a transmission, comprising:
commanding a dog clutch actuator from a first position where a dog clutch is engaged to a second position where the dog clutch is disengaged a predetermined amount of time since commanding a reduction in an electric machine torque, where the predetermined amount of time is based on an estimated dog clutch torque being within a threshold torque of a dog clutch neutral torque, where the dog clutch neutral torque is a motor torque at which there is less than a predetermined amount of torque that is transferred through the dog clutch.
16 . The method for operating the transmission of claim 15 , where the electric machine torque is generated via an electric machine that is coupled to the transmission.
17 . The method for operating the transmission of claim 15 , where the predetermined amount of time is further based on an estimated transfer function of the transmission.
18 . The method for operating the transmission of claim 17 , where the predetermined amount of time is further based on an inertial of an electric machine.