Torque Sensor Single-Output Failure Diagnosis
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Solution Overview
Problem
Conventional torque sensors face challenges with temperature drift compensation, limited dynamic range, and increased transmission lines due to separate diagnostic signal lines for phase and DC components, leading to reduced accuracy and complexity in failure diagnosis.
Innovation Solution
A torque sensor design incorporating a coil, magnetism-responsive members, temperature compensation resistors, a differential amplifier circuit, and an offset voltage generation circuit to produce a single differential signal containing torque and failure information, allowing for simplified transmission via a single output line and improved temperature drift compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate diagnostic circuits are used for phase and DC component detection, then failure diagnosis capability is improved, but device complexity and number of transmission lines increase
Solution Approach 1:
The patent combines separate diagnostic circuits for phase detection and DC component detection into a single integrated circuit. The multiplexer selectively connects either the phase detection circuit or DC component detection circuit to the single output line, allowing both diagnostic functions to share the same transmission path and reducing the number of required transmission lines while maintaining comprehensive failure diagnosis capability
Solution Approach 2:
The single output line is designed to carry multiple types of diagnostic information (phase-related failures and DC component-related failures) by using a multiplexer to switch between different detection circuits. This makes the transmission line universal, capable of conveying various diagnostic data types through a single channel, thereby reducing system complexity
2Adaptability or versatility
If amplification factor of differential amplifier circuit is increased to obtain larger dynamic range, then detection output signal range is improved, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent transforms the single-dimensional approach of simply increasing amplification into a multi-dimensional solution by adding offset voltage generation and selective signal routing. The differential amplifier circuit generates an offset voltage that shifts the output signal range, while the selector circuit chooses between different signal paths (amplified signal or offset voltage) based on operating conditions, thereby expanding dynamic range without consistently amplifying noise
3Measurement precision
If temperature compensation is improved for higher detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service temperature compensation by using the sensor's own output signal to generate the offset voltage. The offset voltage generating circuit processes the sensor output to create a temperature-compensated reference level, allowing the system to automatically adjust for temperature drift without requiring external temperature sensors or complex compensation circuits, thereby maintaining high detection accuracy while limiting complexity increase
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 enhances detection accuracy by expanding the dynamic range and simplifies failure diagnosis with reduced transmission lines, enabling effective temperature drift compensation and accurate failure detection.
Implementation Method 1
at least one coil; a first magnetism-responsive member coupled with the first rotational shaft; and a second magnetism-responsive member coupled with the second rotational shaft, the first and second magnetism-responsive members being configured to cause an impedance change in the coil in response to a relative rotational position of the first and second rotational shafts
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
An excitation AC signal biased by a predetermined DC voltage is applied to a coil to allow a DC voltage component in a coil output signal to contain failure information about disconnection, partial disconnection, or the like of the coil. The DC voltage component contained in the coil output signal is detected, and the detected DC voltage is provided as an offset voltage for a failure diagnosis. Further, to check a peak level of the excitation AC voltage, a DC voltage corresponding to the peak level may be contained in the offset voltage. A differential amplifier circuit for obtaining a difference between a coil detection output AC voltage component and a reference AC voltage component outputs an obtained differential signal offset by the offset voltage. Accordingly, the differential signal containing the offset voltage as the failure information is transmitted to a circuit for torque measurement as a torque detection signal via a single output line. The circuit for torque measurement provides the torque detection data based on the transmitted differential signal and at the same time extracts the offset voltage to use it for the failure diagnosis.