Shift Device Initialization via Travel Path Comparison
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Solution Overview
Problem
Existing methods for initializing the actuation unit of a switching device in powershift transmissions, particularly in dual clutch transmissions, face challenges in determining the absolute position of the switching device when the switching paths differ in both directions of movement, leading to potential transmission malfunctions due to incorrect axial positioning.
Innovation Solution
A method that determines the travel path between two blocking positions of the switching element in both directions and compares it with stored possible travel paths to accurately determine the actual position of the switching device, allowing for initialization without the need for rotary movement or additional position sensors, using the position detection of the actuating unit and motor position sensors for absolute positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the switching device is actuated in both directions to determine absolute position, then the initialization becomes possible without additional sensors, but the switching paths differ in both directions leading to positioning errors
Solution Approach 1:
The patent applies preliminary action by performing multiple preliminary movements of the switching device in both directions before final position determination. The method executes several traversal cycles (at least two) to accumulate position data, then uses this accumulated information to accurately determine the absolute position. This preliminary repeated action compensates for the asymmetric switching paths and enables reliable initialization without additional sensors.
Solution Approach 2:
The patent implements feedback by continuously monitoring the position of the switching device during each traversal movement using existing sensors. The position information from each movement is fed back to the control unit, which processes this data to determine the actual switching path. This feedback mechanism allows the system to adapt to the asymmetric paths and accurately calculate the absolute position despite the differences in movement directions.
2Measurement precision
If additional position sensors are installed to determine absolute position, then positioning accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The patent applies self-service by enabling the existing actuation unit and position sensors to perform the absolute position determination function themselves, without requiring additional dedicated position sensors. The control unit utilizes the position information already available from the actuation process to calculate the absolute position of the switching device. This self-service approach eliminates the need for extra sensors while maintaining accurate positioning capability.
Solution Approach 2:
The patent implements universality by making the existing position sensors serve multiple functions: they both control the actuation process and determine the absolute position of the switching device. The same sensors that monitor the actuation unit's position during normal operation are also used to establish the absolute reference position during initialization. This multi-functional use of existing components avoids adding specialized absolute position sensors.
3Measurement precision
If the switching device requires rotary movement for initialization, then absolute position can be determined, but the initialization time and complexity increase
Solution Approach 1:
The patent applies mechanics substitution by replacing the traditional rotary movement mechanism with a linear traversal movement of the switching device along its axis. Instead of rotating the actuation unit to determine position, the method moves the switching device back and forth along its linear path and uses the position sensors to detect the blocking positions. This substitution of linear movement for rotary movement simplifies the initialization process and reduces the time required while maintaining accurate position determination.
Data Source
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AI summary
The invention relates to a method for initializing the actuation unit (9) of a shift device (8), which can be moved in both movement directions along a shift shaft (6), for the alternate connection of two gearwheels (5a, 5b) into a transmission power flow, in which method a sensor (11) of the actuation unit (9) is used for detecting the position of the shift device (8), for which purpose the shift device (8) is moved successively in both movement directions as far as the blocked end position at the respective gearwheel (5a, 5b), wherein from this the movement travel (x) between the two blocked positions is determined, said movement travel subsequently being compared with the stored four possible movement travels (xNB, XGB, Xli, Xre), from which the actual position of the shift device (8) is established in order to initialize the actuation unit (9) in the case of different shift-through travels (S4 to S2, S1 to S3) in the two movement directions.