LC Resonant Inductive Sensor Assembly for Minor Position Detection
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Solution Overview
Problem
Existing inductive sensor assemblies for detecting actuation in motor vehicles face challenges in reliable and economical detection of minor position changes of metallic actuating elements, particularly in fixed door handles.
Innovation Solution
An inductive sensor assembly utilizing an LC resonant circuit with a decoupling element and evaluation assembly, including a high-impedance series resistor and microcontroller-based excitation supply, measures electromagnetic properties to detect position changes through rectified voltage signals, reducing time-dependent measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional inductive sensor assembly is used to detect position changes of metallic actuating elements, then detection capability is provided, but manufacturing cost and complexity increase
Solution Approach 1:
The patent combines the excitation supply and evaluation assembly into a single integrated circuit board, reducing the number of separate components and connections. This merging of functions decreases device complexity while maintaining detection reliability through the unified architecture that coordinates excitation and signal evaluation.
Solution Approach 2:
The LC resonant circuit serves multiple functions: it generates the excitation signal for the coil, acts as the sensing element for detecting position changes, and provides the signal evaluation pathway. This multi-functionality reduces the need for separate dedicated components, thereby reducing overall device complexity while maintaining reliable detection.
2Measurement precision
If high-precision detection of minor position changes is implemented, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent employs an LC resonant circuit that operates at a specific resonant frequency to detect position changes. By utilizing resonance, the system achieves high measurement precision for minor position changes (micrometer range) because resonant systems are highly sensitive to changes in their operating conditions, such as inductance variations caused by actuating element movement.
Solution Approach 2:
The detection mechanism relies on monitoring changes in the resonant frequency and quality factor (Q) of the LC circuit as the actuating element moves. These parameter changes provide a sensitive and precise measure of position without requiring complex mechanical measurement systems, thereby achieving high precision with relatively simple electronics.
3Measurement precision
If time-dependent measurement methods are used, then detection capability is achieved, but measurement errors and false positives increase
Solution Approach 1:
The patent replaces time-dependent mechanical or sequential measurement methods with a frequency-based resonant detection method. By measuring the resonant frequency and quality factor of the LC circuit, the system obtains position information that is independent of time resolution, eliminating the timing errors and false positives associated with time-dependent measurement approaches.
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
Provides a robust and cost-effective method for detecting actuation changes with high sensitivity and reduced false positives by measuring rectified voltage signals, independent of time resolution, suitable for motor vehicle applications.
Implementation Method 1
The functional principle of inductive sensor assemblies is based on the detection of a change in an electromagnetic field when a metallic or ferromagnetic actuating element moves in the electromagnetic field. The underlying physical effect is the change in the inductance and/or the quality of the inductance as a result of a change in position of the conductive and/or ferromagnetic element
Implementation Method 2
an LC resonant circuit having an inductive element (L), preferably a coil or a combination of a plurality of coils, and having a capacitive element (C)
Data Source
AI summary
An inductive sensor assembly is used for detecting a change in position of an actuating element. The sensor assembly has: an LC resonant circuit having an inductive element (L) and a capacitive element (C); an excitation supply which is coupled to the LC resonant circuit in order to excite the LC resonant circuit with an excitation voltage (U); a decoupling element arranged between the excitation supply and the LC resonant circuit; and, an evaluation arrangement for evaluating the signal decreasing across the resonant circuit. An actuating assembly is also provided.