Automatic Transmission Shift Element Disengagement Control
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Solution Overview
Problem
Automatic transmissions face challenges in uniformly disengaging shifting elements due to friction wear and tolerance stacking, affecting performance and gear disengagement consistency.
Innovation Solution
A method for operating an automatic transmission that involves adjusting the shift lever to a neutral or park position, measuring the input speed, establishing a launch time for the turbine, and adjusting the command pressure of the shifting element based on the launch time to ensure uniform disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If friction shift elements are used in automatic transmission, then power transmission and gear shifting are enabled, but wear over time affects performance and reaction consistency of the shift elements
Solution Approach 1:
The patent implements a feedback control system that measures actual shift element disengagement characteristics and uses this information to adjust control parameters. Sensors monitor shift element position and speed, and the control unit modifies hydraulic pressure or motor commands in real-time to compensate for wear, maintaining consistent performance throughout the service life of the transmission.
Solution Approach 2:
The patent dynamically adjusts control parameters such as hydraulic pressure magnitude, ramp rate, and timing based on detected shift element characteristics. By changing these parameters in response to wear or varying conditions, the system maintains optimal disengagement performance without requiring physical replacement of worn components.
2Ease of manufacture
If tolerance stacking of shifting element components is present, then manufacturing and assembly are simplified, but uniform performance between automatic transmissions becomes difficult to provide
Solution Approach 1:
The control system measures actual shift element disengagement characteristics during operation and uses this feedback to compensate for variations caused by tolerance stacking. The control unit adjusts hydraulic pressure profiles or motor control parameters based on detected performance deviations, ensuring uniform transmission behavior across different units despite manufacturing tolerances.
Solution Approach 2:
The patent transitions from static, fixed control parameters to dynamic, adaptive control that responds to actual shift element behavior. By continuously monitoring and adjusting control parameters based on real-time measurements, the system compensates for manufacturing variations and achieves uniform performance across different transmissions.
3Reliability
If shift elements are opened uniformly, then gear disengagement is improved, but friction wear and tolerance stacking impede uniform opening
Solution Approach 1:
The system uses sensors to monitor the actual opening process of shift elements and compares it to desired uniform opening characteristics. Based on this feedback, the control unit adjusts hydraulic pressure application or motor control in real-time to correct deviations from uniform opening, compensating for friction and wear effects.
Solution Approach 2:
The patent applies preliminary hydraulic pressure or motor activation before actual disengagement is needed, gradually building up force to overcome static friction and ensure uniform opening. This preliminary action allows the system to anticipate and compensate for friction effects before they impede the shifting process.
Data Source
AI summary
A method for operating an automatic transmission is provided. The method includes disengaging a shifting element of the automatic transmission and measuring an input speed of the automatic transmission while the shifting element is disengaging. A command pressure of the shifting element is adjusted to a target command pressure based at least in part on the input speed of the automatic transmission while the shifting element is disengaging.