Dog Clutch Actuation Timing for Faster Low-Energy Shifting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Dog clutches in transmissions face challenges with high torque resistance during gear shifts, leading to increased shift times and energy consumption due to the need for the shift actuator to overcome dog clutch torque, which is influenced by electric torque, frictional drag, and inertial torque.
Innovation Solution
A method is implemented where the dog clutch actuator is commanded to disengage a predetermined time after reducing electric machine torque, optimizing the shift process by reducing the force and energy required for gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the dog clutch actuator is commanded to disengage immediately, then the shift time is reduced, but the force required to overcome dog clutch torque increases and energy consumption rises
Solution Approach 1:
The system commands a reduction in electric machine torque before commanding the dog clutch actuator to disengage. This preliminary torque reduction lowers the dog clutch torque that must be overcome during disengagement, thereby reducing the force required from the actuator and the energy consumed during the shift process.
Solution Approach 2:
The system changes the torque parameter of the electric machine from a higher value to a reduced value before actuator engagement. This parameter change reduces the resistance torque in the transmission, making it easier for the dog clutch actuator to disengage the clutch and reducing overall energy consumption during the shift.
2Speed
If the dog clutch actuator is commanded to disengage immediately, then the shift speed increases, but the force applied to shift forks and dog clutches increases
Solution Approach 1:
The system reduces electric machine torque before commanding the dog clutch actuator to move. This preliminary action reduces the dog clutch torque that opposes disengagement, allowing the actuator to move the clutch with less force while maintaining efficient shift timing.
Solution Approach 2:
The system applies a counter-action by reducing electric machine torque before the dog clutch disengagement. This preliminary anti-action opposes the buildup of high dog clutch torque, thereby reducing the force required from the actuator to overcome the torque during disengagement.
3Force
If electric machine torque is reduced before disengagement, then the force required to disengage the dog clutch is reduced, but the shift process takes longer
Solution Approach 1:
The system changes the torque parameter of the electric machine to a reduced value before actuator engagement. This parameter change optimizes the balance between reducing the force required for disengagement and maintaining acceptable shift timing by lowering resistance without excessive delay.
Data Source
AI summary
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.