Inductively Coupled Pressure Sensor with Self-Tuning Oscillator
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Solution Overview
Problem
Contemporary pressure sensors face challenges in protecting sensitive components from harsh environments, such as engine exhaust, which leads to reduced accuracy and shorter sensor lifespan due to the use of protective materials that break down over time, and requires additional components for temperature compensation, increasing costs and space.
Innovation Solution
A capacitive pressure sensor assembly with a self-tuning oscillator circuit that automatically matches the resonant frequency of a tank circuit, using a variable capacitor and primary coil to maintain stability and accuracy, while integrating temperature compensation without additional protective materials, and utilizing materials like silicon and gold for the sensor coil to withstand harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protective materials (gel or coating) are deposited over the sensor and electronics to seal vulnerable electrical connections from harsh media, then the sensor components are protected from harsh environments, but additional manufacturing steps are introduced and the protective materials break down over time shortening sensor life
Solution Approach 1:
The patent extracts the sensitive electronics from the harsh environment by creating a sealed sensor compartment that houses only the pressure sensor, while the electronics compartment containing the electronic assembly is isolated and protected. This separation eliminates the need for protective coatings on electrical connections while maintaining protection from harsh media.
Solution Approach 2:
The housing is divided into distinct sensor compartment and electronics compartment separated by a substrate. This segmentation allows each component to be optimized for its specific requirements - the sensor compartment can withstand harsh environments while the electronics compartment remains protected, eliminating the need for universal protective materials.
2Reliability
If protective materials are used to seal electrical connections from harsh media, then the sensor is protected, but the protective materials break down over time losing protective ability and shortening sensor useful life
Solution Approach 1:
The patent removes the need for protective materials by extracting the electronics from direct exposure to harsh media through sealed compartments. The sensor itself is protected by the sealed sensor compartment while electronics are protected by the separate electronics compartment, eliminating the degradation issue of protective coatings over time.
3Measurement precision
If additional sensors or components are added for temperature compensation and correction, then temperature related inaccuracies are mitigated, but costs and space requirements increase
Solution Approach 1:
The coil serves multiple functions: it is part of the resonant circuit for pressure measurement and simultaneously acts as a temperature sensor. The resonant frequency of the coil changes with temperature, allowing the same component to provide both pressure sensing and temperature compensation without adding separate components.
Solution Approach 2:
The patent combines the temperature sensing function with the existing coil component of the resonant circuit. By utilizing the temperature-dependent resonant frequency characteristics of the coil, the system merges pressure measurement and temperature compensation into a single integrated solution, reducing component count and cost.
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 effectively protects sensitive electronics from harsh environments, provides accurate pressure and temperature data, and optimizes sensor system accuracy without the need for additional protective materials, reducing costs and space requirements.
Implementation Method 1
A sensor assembly includes a housing and a sensor compartment isolated from an electronics compartment. A sensor forms a tank circuit including a coil and a capacitive pressure sensor. An electronic assembly includes a primary coil and an application-specific integrated circuit
Implementation Method 2
A sensor forms a tank circuit including a coil and a capacitive pressure sensor
Data Source
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AI summary
In one embodiment, a pressure sensor assembly for use with an application specific integrated circuit includes a capacitive sensor, a sensor coil within a first sensor compartment and operatively connected to the capacitive sensor to form a sensor L-C tank circuit, a measuring oscillator including a measuring coil located within a second sensor compartment and spaced apart from the sensor coil and a feedback circuit configured to provide a control signal for the measuring oscillator based upon an output of the measuring oscillator, and a low frequency signal source configured to provide a low frequency signal to the measuring oscillator.