Inductive Sensor for Simultaneous Speed and Position Detection
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Solution Overview
Problem
Current sensor technologies require multiple devices to accurately detect the position and speed of a linearly moving object, such as a piston in a combustion engine, and struggle to determine real-time torque with high accuracy due to manufacturing tolerances and environmental harshness.
Innovation Solution
A single inductive sensor device with an oscillator circuit and processing unit that induces eddy currents in the object, allowing for simultaneous detection of speed and position by counting oscillations and comparing them to a predetermined mean value, eliminating the need for additional markers and enabling accurate torque determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensor devices are used to detect position and speed, then separate devices are needed for each measurement, but this increases device complexity and requires additional markers
Solution Approach 1:
The patent combines position and speed detection functions into a single inductive sensor device. The oscillator circuit with sensing coil simultaneously provides both position information (through impedance changes) and speed information (through frequency changes), eliminating the need for separate optical sensors and markers.
Solution Approach 2:
The inductive sensor device performs multiple functions: it detects both position and speed of the piston, and can also determine torque. This multi-functional capability replaces multiple specialized sensors, reducing overall system complexity while maintaining measurement precision.
2Measurement precision
If multiple sensor devices and markers are used, then measurement coverage is improved, but manufacturing complexity and costs increase
Solution Approach 1:
By merging position and speed detection into one inductive sensor, the patent eliminates the need for manufacturing additional optical sensors and markers on the piston. This reduces manufacturing steps, assembly complexity, and overall system cost while achieving simultaneous measurement of both parameters.
Solution Approach 2:
The patent replaces mechanical/optical marker systems with an inductive sensing system that detects changes in the oscillator circuit's electrical characteristics. This substitution eliminates the need for physical markers and complex optical alignment, simplifying manufacturing.
3Measurement precision
If conventional optical sensors are used, then position detection is achieved, but robustness against harsh environments deteriorates
Solution Approach 1:
The patent replaces optical sensor systems with an inductive sensing system based on electromagnetic induction. This substitution provides robustness against harsh environments (high temperature, dust, vibration) while maintaining position sensing accuracy, as inductive sensors have no moving parts and are sealed against environmental contaminants.
4Reliability
If eddy current sensors are used, then robustness in harsh environments is improved, but the ability to determine real-time torque with high accuracy deteriorates
Solution Approach 1:
The patent uses feedback from the oscillator circuit's resonance frequency changes to determine torque. The processing unit continuously monitors frequency variations caused by eddy currents and uses this feedback to calculate real-time torque, achieving both robustness and accuracy.
Solution Approach 2:
The patent monitors changes in electrical parameters (resonance frequency, impedance) of the oscillator circuit in response to eddy currents. By analyzing these parameter changes, the system can determine torque with high accuracy while maintaining robustness in harsh environments.
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
Enables precise and simultaneous measurement of speed and stroke of a linearly moving object without mechanical contact, reducing manufacturing complexity and operating costs, while maintaining accuracy in harsh environments.
Implementation Method 1
The current generator causes a high-frequency alternating electrical current flowing in the detector coil that is associated with a high-frequency time-varying magnetic field (primary magnetic field). This primary magnetic field induces eddy currents in an electrically conductive object to be detected that in course induce a secondary magnetic field
Implementation Method 2
This primary magnetic field induces eddy currents in an electrically conductive object to be detected that in course induce a secondary magnetic field that, according to Lenz's law, is directed oppositely to the primary magnetic field
Implementation Method 3
This secondary magnetic field affects the impedance and, thus, the resonance frequency f0 of the oscillator circuit (f0=1/(2π(LC)1/2), with L and C denoting the inductance and capacitance of the oscillator circuit, respectively)
Data Source
AI summary
An inductive sensor device for detecting a reciprocating movement of an object includes an oscillator circuit and a processing unit. The oscillator circuit has a sensing coil configured for inducing eddy currents in the object. The processing unit is configured to count a plurality of oscillations of the oscillator circuit detected in a plurality of sampling periods, compare the oscillations with a predetermined mean value of oscillations, and determine both a speed and a position of the object based on a comparison of the oscillations with the predetermined mean value of oscillations.