Hybrid Sensor for Rotational Speed Detection
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Solution Overview
Problem
Existing speed sensors in hybrid and electric vehicles fail to provide the required measurement accuracy over the entire speed range, particularly at lower and higher speeds from 1 to 25,000 revolutions per minute, due to limitations in mechanical robustness and resolution.
Innovation Solution
A sensor device combining a passive inductive sensor and an active magnetic sensor, with a magnetic field generator and incremental carrier, allows for extended speed range detection from 0 to over 20,000 revolutions per minute by leveraging increasing signal-to-noise ratio with rotational speed, and redundant signal accuracy in overlapping ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensor type is used for speed detection, then the device complexity is reduced, but the measurement precision deteriorates at extreme speeds (below 1 rpm or above 25,000 rpm)
Solution Approach 1:
The speed detection function is segmented into two distinct sensor systems: a first sensor for low-speed detection (0-1000 rpm) and a second sensor for high-speed detection (1000-25000 rpm). Each sensor is optimized for its specific speed range, allowing high measurement precision within each segment while managing overall device complexity through functional division.
Solution Approach 2:
The system dynamically switches between the first and second sensors based on the detected speed range. The control unit activates the appropriate sensor according to current operating conditions, enabling the system to adapt its measurement capabilities to match the required precision for each speed regime without maintaining both sensors continuously active.
2Measurement precision
If the rotational speed increases, then the signal-to-noise ratio for inductive sensors improves, but the maximum detectable speed is limited by the incremental frequency of active sensors
Solution Approach 1:
The system changes the active sensing parameter based on speed conditions: at low speeds where signal-to-noise ratio is poor, the inductive sensor's natural frequency response is utilized; at high speeds where incremental frequency becomes limiting, the system transitions to the active magnetic sensor which can handle higher frequencies. This parameter switching resolves the contradiction between signal quality and speed capability.
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 sensor device achieves high measurement accuracy and extended speed range detection, from nearly standstill to high rotational speeds, by effectively combining passive inductive and active magnetic sensing principles, reducing limitations in resolution and interference.
Implementation Method 1
The first magnetic sensor is a passive inductive sensor which preferably has at least one coil which is set up to detect a magnetic field generated or changed by eddy currents of the rotating element
Implementation Method 2
at least one coil which is set up to detect a magnetic field generated or changed by eddy currents of the rotating element
Implementation Method 3
The second magnetic sensor is an active sensor, which preferably has at least one Hall element and/or at least one magnetoresistive element
Implementation Method 4
The second magnetic sensor is an active sensor, which preferably has at least one Hall element and/or at least one magnetoresistive element
Data Source
AI summary
A sensor device (10) for determining at least one rotational property of a rotating element is proposed, comprising at least one increment carrier (20) connectable to the rotating element, wherein the sensor device (10) comprises at least one magnetic field generator (12) for generating a magnetic field at the location of the rotating element, wherein the sensor device (10) has at least one first magnetic sensor (16) and at least one second magnetic sensor (18), wherein the first magnetic sensor (16) generates a first sensor signal and the second magnetic sensor (18) generates a second sensor signal, wherein the first magnetic sensor (16) is an inductive sensor, wherein the first magnetic sensor (16) has at least one coil and is configured to detect a magnetic field generated or modified by eddy currents of the rotating element;wherein the second magnetic sensor (18) is an active sensor, wherein the second magnetic sensor (18) comprises at least one Hall element and/or at least one magnetoresistive element.;