Transmission Shift Element Pressure-Torque Curve Segmentation
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Solution Overview
Problem
Existing methods for actuating friction-locking shift elements in transmissions lack precision and quality due to their reliance on linear pressure versus torque characteristic curves, which do not allow for accurate control between the touch point and contact point.
Innovation Solution
Implementing a pressure versus torque characteristic curve subdivided into multiple ranges with distinct functional dependencies between power transmission capacity and actuating pressure, including a first range between the touch point and contact point, and additional ranges for enhanced engagement and transition states, such as with a wave spring, to improve actuation precision and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear pressure versus torque characteristic curve is used for pressure control, then the control system is simple, but the actuation precision and quality are insufficient
Solution Approach 1:
The pressure versus torque characteristic curve is segmented into multiple characteristic ranges (first range from touch point to contact point, second range after contact point). Each range has its own functional dependence between power transmission capacity and actuating pressure. This segmentation allows precise control in each specific engagement stage while maintaining manageable system complexity through structured control logic.
Solution Approach 2:
The functional dependence between power transmission capacity and actuating pressure is changed based on the engagement stage. In the first characteristic range (touch point to contact point), a first functional dependence is used, while in the second characteristic range (after contact point), a second functional dependence is used. This parameter change enables precise actuation control adapted to different physical states of the friction-locking shift element.
2Manufacturing precision
If a single functional dependence is used across all engagement stages, then the control logic is simple, but the quality requirements are not met
Solution Approach 1:
The control system dynamically adapts the functional dependence between power transmission capacity and actuating pressure based on the current engagement stage. The control unit determines which characteristic range applies (first range or second range) and selects the appropriate functional dependence accordingly. This dynamic adaptation enables high engagement precision while keeping control logic complexity manageable through clear state-based decision making.
Solution Approach 2:
Different functional dependences are applied in different engagement stages. The first functional dependence is used in the first characteristic curve range (from touch point to contact point), and the second functional dependence is used in the second characteristic curve range (after contact point). This parameter change strategy achieves precise engagement control while maintaining structured and manageable control logic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise and high-quality actuation of friction-locking shift elements by varying the functional dependence of power transmission capacity with respect to actuating pressure across different engagement stages, enhancing the overall control and accuracy of transmission operations.
Implementation Method 1
The shift element begins to transmit torque due to friction between shift element halves only once the shift element has been further engaged beyond the touch point and a clearance of the shift element has been overcome
Data Source
AI summary
A method for operating a friction-locking shift element of a transmission of a motor vehicle includes actuating the friction-locking shift element for engagement according to a pressure versus torque characteristic curve. The pressure versus torque characteristic curve has a first characteristic point (a touch point) and a second characteristic point (a contact point), defines a first characteristic curve range between the touch point and the contact point having a first functional dependence, and defines a second characteristic curve range at or after the contact point having a second functional dependence. Once the touch point is reached, the friction-locking shift element begins to transmit torque mainly due to drag torques. Whereas, once the contact point is reached, the friction-locking shift element begins to transmit torque mainly due to friction between shift-element halves of the friction-locking shift element.