Automatic Transmission Shift Control Using Torque Capacity Feedback
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Solution Overview
Problem
Automatic transmissions face issues with uncontrolled engine speed rises due to insufficient torque capacity in the on-coming clutch during gear shifts, leading to noise, vibration, and reduced driveability when the off-going clutch is released.
Innovation Solution
The method involves stroking the on-coming element while reducing pressure for the off-going element, then increasing pressure for the on-coming element once it has sufficient torque capacity, and adjusting torque capacities based on transmission output and input torque and acceleration to ensure smooth gear shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the on-coming clutch has insufficient torque capacity when the off-going clutch is released, then the gear shift can be initiated, but an uncontrolled rise in engine speed occurs causing noise, vibration, and harshness
Solution Approach 1:
The system performs preliminary action by pre-stroking the on-coming clutch before the off-going clutch is fully released. This ensures the on-coming clutch is ready to immediately承接 torque without insufficient capacity, preventing uncontrolled engine speed rise while maintaining smooth gear shift operation
Solution Approach 2:
The system uses feedback by continuously monitoring the torque capacity of the on-coming clutch and adjusting its stroke accordingly. When sufficient torque capacity is detected, the system proceeds with the gear shift; when insufficient, it delays the release of the off-going clutch, creating a closed-loop control that eliminates noise and vibration
2Reliability
If the on-coming clutch torque capacity is increased too early, then sufficient torque capacity is ensured, but the off-going clutch cannot be released causing delayed gear shift
Solution Approach 1:
The system applies dynamics by making the on-coming clutch stroke dynamic rather than static. The clutch stroke is continuously adjusted based on real-time torque capacity requirements, allowing the system to optimize between ensuring sufficient torque capacity and minimizing gear shift time under varying operating conditions
3Productivity
If the off-going clutch is released before the on-coming clutch has sufficient torque capacity, then gear ratio change can begin, but uncontrolled engine speed rise occurs
Solution Approach 1:
The system applies preliminary anti-action by pre-stroking the on-coming clutch in advance to build sufficient torque capacity before the off-going clutch is released. This counteracts the potential harmful effect of uncontrolled engine speed rise by ensuring the on-coming clutch is ready to immediately承接 the torque load
Data Source
AI summary
A method of downshifting an automotive transmission. An on-coming transmission element is stroked while pressure for an off-going element is reduced. Pressure for the stroked on-coming element is increased to be sufficient to carry torque. Pressure for the off-going element is reduced below a torque transmitting amount once the stroked on-coming element has a sufficient torque carrying capacity. Torque capacities for the elements are determined from transmission output torque and acceleration and transmission input torque and acceleration. Feed forward or feedback terms for off-going and on-coming element torque capacities may be calculated using the transmission output torque, transmission input acceleration, and transmission input torque.