Selector Fork Backlash Compensation for Accurate Gear Shifting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for positioning a selector fork via an actuator face challenges due to hysteresis, which complicates precise positioning and leads to wear over the component's service life, especially when using materials like plastic for the sliding shoes to achieve self-lubricating properties.
Innovation Solution
A method utilizing a state machine for hysteresis compensation in the actuator, allowing precise positioning of the selector fork by correcting mechanical backlash between the actuator and the selector fork, using a position-controlled actuator and sensors like Hall sensors, enabling open-loop or closed-loop control to accurately position the selector fork.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position-controlled actuator is used to move the selector fork, then positioning capability is provided, but hysteresis occurs during movement sequences causing positioning inaccuracies
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual position of the selector fork via a sensor and comparing it with the target position. Based on this comparison, the control unit adjusts the actuator's control signal to compensate for hysteresis effects, ensuring the fork reaches the desired position accurately despite the actuator's inherent hysteresis characteristics.
Solution Approach 2:
The patent changes the control parameter by introducing a correction value that is added to the target position. This correction value is determined based on the current position and the direction of movement, effectively compensating for hysteresis by dynamically adjusting the positioning parameter rather than relying on the actuator's inherent positioning capability alone.
2Ease of manufacture
If mechanical backlash exists between the actuator and selector fork, then assembly is simplified, but positioning precision deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for different position ranges in a lookup table. Before actual positioning occurs, the control unit determines the appropriate correction value based on the current state, allowing the system to compensate for backlash without requiring complex real-time calculations or mechanical pre-adjustments.
Solution Approach 2:
The patent compensates for mechanical backlash by dynamically changing the control parameter (target position) based on the current position and movement direction. The correction value, stored in a lookup table, adjusts the effective target position to account for backlash, thereby maintaining positioning precision despite the presence of mechanical clearances in the assembly.
3Reliability
If sliding shoes are made from plastic or brass for self-lubricating properties, then wear resistance improves, but friction characteristics change affecting positioning
Solution Approach 1:
The patent applies self-service by using plastic or brass sliding shoes that provide self-lubricating properties. These materials contain lubricants or have low-friction surfaces that automatically reduce friction during operation without requiring external lubrication, thereby maintaining consistent friction characteristics and positioning accuracy throughout the component's service life.
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 method allows for precise and flexible positioning of the selector fork, reducing wear and maintaining positioning accuracy while accommodating component tolerances, thus providing a robust solution for systems with backlash.
Implementation Method 1
Actuators generally exhibit hysteresis during their sequence of movements. This means that the actuator moves from a first state into a second state for example when a control signal is applied. If the control signal is set back to 'zero ', the actuator no longer returns fully into the first state, however.
Implementation Method 2
the position of the actuator is corrected on the basis of stored mechanical backlash between the actuator and the selector fork
Implementation Method 3
sensors like Hall sensors
Data Source
AI summary
A method for hysteresis compensation in an actuator and a selector fork that is adjustable by this actuator and guides a sliding sleeve, by means of a state machine, wherein the selector fork is moved by means of the actuator from a first shift position (xDecoup), namely a neutral position, into at least one second shift position (xCoup), namely a gear position, and vice versa, wherein the position of the actuator (phiAtr, phiCoup, phiDecoup), in the event of a shift request into the neutral position (xDecoup) or into the gear position (xCoup), is corrected on the basis of stored mechanical backlash (phiBL) between the actuator and the selector fork and of a sign (+1, 0, −1) generated by the state machine and associated with the particular shift request.