Gearbox Neutral Position Detection Using Digital Signal Processing
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Solution Overview
Problem
Existing gearbox position sensors fail to reliably detect the neutral position and identify faults such as inappropriate impedance in the electric circuit, which can lead to incorrect signal interpretation and safety issues, especially in systems like STOP&START for automated gearboxes.
Innovation Solution
A motor vehicle gearbox position sensor equipped with a Hall effect probe and a signal processing unit featuring an analog-digital converter that converts analog signals into digital output signals with predefined periodic information, ensuring accurate neutral position detection only when the sensor is in a normal operating state, and includes diagnostic capabilities to identify potential faults like contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an analog signal is used to represent gearbox position, then the sensor structure remains simple, but the signal is vulnerable to impedance faults and cannot reliably indicate neutral position
Solution Approach 1:
The patent replaces the purely analog signal transmission system with a digital signal system. The analog signal from the probe is converted to a digital signal through an analog-digital converter, which then transmits position information in a digital format. This substitution eliminates the vulnerability to impedance faults that plague analog signals, as digital signals are inherently more robust against such electrical disturbances.
Solution Approach 2:
The patent implements a feedback mechanism where the digital signal includes not only position information but also diagnostic information about the sensor's operating state. The system continuously monitors its own functionality and provides feedback about its health status, enabling reliable detection of neutral position while maintaining awareness of potential faults.
2Difficulty of detecting and measuring
If additional diagnostic circuits are added to detect faults, then fault identification capability improves, but the sensor complexity and cost increase
Solution Approach 1:
The patent makes the digital signal processing unit multi-functional. It not only converts analog signals to digital format for position indication but also simultaneously performs diagnostic functions to detect faults in the electric circuit. This universal approach allows fault detection capability to be integrated into the existing signal processing architecture without adding separate dedicated diagnostic circuits, thereby avoiding excessive complexity.
Solution Approach 2:
The sensor system performs self-diagnosis by monitoring its own operating parameters and signal characteristics. The digital processing unit analyzes the incoming analog signal and the resulting digital signal to detect anomalies indicating faults in the electric circuit, such as inappropriate impedance. This self-service capability enables fault detection without requiring external diagnostic equipment or complex additional circuits.
3Reliability
If an analog signal with intermediate values is used to prevent short-circuit misinterpretation, then protection against ground short circuits improves, but the signal cannot distinguish cable impedance faults from valid position signals
Solution Approach 1:
The patent replaces the analog signal system with intermediate voltage levels with a digital signal system. Instead of using analog voltage levels where intermediate values attempt to represent both protection and position information, the system converts to digital signals that provide discrete, unambiguous states. This substitution fundamentally resolves the ambiguity problem, as digital signals can clearly distinguish between valid position data and fault conditions through their binary nature and associated diagnostic flags.
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
The solution provides a reliable, secure, and cost-effective gearbox position sensor with enhanced diagnostic capabilities, ensuring accurate gear position detection and fault identification, thereby improving safety and reducing maintenance needs.
Implementation Method 1
A motor vehicle gearbox position sensor equipped with a Hall effect probe
Data Source
AI summary
The invention relates to a motor vehicle gearbox position detector comprising a sensor (3) designed to cooperate with a moving target (5) connected to a gearbox ratio actuation element so as to provide at least one analog signal representative of the position of the neutral point of the gearbox, characterized in that it additionally comprises a unit for processing the signal (9) comprising an analog-to-digital converter designed to convert the analog signal into a digital output signal (17) so as to provide periodic predefined information corresponding to the position of the neutral point only when, on the one hand, the target (5) is in the neutral point position and, on the other hand, when the sensor (1) is in the normal operating state.