Transmission Gear Position Detection Using Ratio Cross-Checks
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Solution Overview
Problem
Existing gear position detection methods in automated mechanical transmissions are unreliable, leading to potential vehicle acceleration or deceleration failures and safety risks, as they solely rely on direct detection of the shift fork's linear displacement, which can fail or become inaccurate near critical thresholds.
Innovation Solution
A method that determines the gear position by comparing the transmission ratio from a first position sensor with the ratio calculated from input and output shaft speeds, and optionally uses a second position sensor to verify the shift fork's neutral position, entering a gear error handling subroutine when discrepancies are found, ensuring accurate gear position identification and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gear position is determined by directly detecting the linear displacement of the shift fork using a single position sensor, then the detection method is simple, but the reliability of gear position identification is poor
Solution Approach 1:
The patent combines multiple detection methods into a unified gear position identification system. It merges direct position sensor detection with transmission ratio calculation based on shaft speeds, and further integrates neutral position detection through a second position sensor. This combination allows the system to cross-validate results and identify gear position more reliably, resolving the contradiction between simplicity and reliability.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring multiple parameters (position sensor readings, shaft speeds, calculated transmission ratios) and comparing them against expected values. When discrepancies are detected, the system can identify potential failures and switch to alternative detection methods or trigger error handling routines, thereby improving reliability through continuous validation and correction.
2Measurement precision
If a single position sensor is used to detect shift fork displacement, then the device complexity is low, but measurement precision deteriorates near critical thresholds
Solution Approach 1:
The patent segments the gear position detection task into multiple independent detection paths. The first position sensor detects general shift fork position, the second position sensor specifically detects neutral position, and the transmission ratio calculation provides an independent verification method. This segmentation allows each sensor to be optimized for its specific function and provides redundancy, improving measurement precision without requiring a single complex sensor.
Solution Approach 2:
The patent introduces an intermediary calculation method (transmission ratio based on shaft speeds) that acts as a mediator to verify position sensor readings. This intermediary approach provides an independent check on gear position that does not rely directly on position sensor accuracy, thereby improving measurement precision especially near critical thresholds where sensor readings may be ambiguous.
3Reliability
If gear position detection relies solely on shift fork linear displacement, then the detection approach is straightforward, but the system is vulnerable to sensor failure and inaccurate identification
Solution Approach 1:
The patent applies local quality by assigning different detection methods to different gear conditions. The first position sensor is used for general gear position detection, while the second position sensor is specifically deployed for neutral position verification. The transmission ratio calculation serves as a local verification method that is particularly useful when position sensor readings are ambiguous or conflicting. This localized application of different detection strategies improves robustness against sensor failure.
Solution Approach 2:
The patent implements beforehand cushioning by preparing multiple detection methods and validation routines in advance. When the primary position sensor fails or provides inaccurate readings, the system can switch to alternative methods (second position sensor, transmission ratio calculation) without losing gear position identification capability. This preparatory redundancy cushions against sensor failure and maintains system reliability.
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 improves the reliability of gear position detection, reducing the risk of unexpected vehicle acceleration or deceleration and enhancing operational safety by cross-checking gear positions through multiple sensors, thereby preventing potential accidents.
Implementation Method 1
the second position sensor may be a Hall sensor used to detect a rotor angle of a shift motor
Data Source
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AI summary
The present application relates to a method for detecting a gear position of a vehicle transmission. This method comprises determining a position of a shift fork from a first position sensor; comparing a first transmission ratio and a second transmission ratio when it is determined that the first position sensor indicates that the shift fork is not in neutral, wherein the first transmission ratio is determined by the first position sensor and the second transmission ratio is determined by an input shaft speed and an output shaft speed of the transmission; and entering a gear error handling subroutine when it is determined that the first transmission ratio and the second transmission ratio do not match.