Multiplexer Signal Classification for Gas Sensor Sampling
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Solution Overview
Problem
Existing gas sensor control systems face challenges in increasing sampling frequency for quicker response without significantly increasing the cost and size of analog-to-digital converters, particularly in demanding applications like multi-cylinder engine combustion state control.
Innovation Solution
A sensor control apparatus that employs a multiplexer to classify analog signals as high or low occurrence-frequency signals, allowing for increased sampling frequency of high-frequency signals like electromotive force without upgrading the AD converter, while using digital-to-analog conversion to control pump current and incorporating filter sections to improve signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the sampling frequency in AD conversion is increased to achieve quicker response, then the response speed is improved, but the cost and size of the AD converter increases
Solution Approach 1:
The patent segments the signal processing by separating high occurrence-frequency signals (electromotive force) from low occurrence-frequency signals (pump current, temperature). High-frequency signals are sampled at higher rates while low-frequency signals are sampled at lower rates, allowing the AD converter to operate at moderate speeds while still capturing critical high-frequency variations accurately.
Solution Approach 2:
The patent implements periodic sampling with varying frequencies based on signal importance. The electromotive force signal is sampled at a higher periodic rate than the pump current signal, creating a multi-rate sampling scheme that optimizes response speed for critical parameters while reducing overall sampling burden on the AD converter.
2Measurement precision
If the sampling frequency is increased to detect electromotive force accurately, then the measurement precision is improved, but the AD converter cost increases
Solution Approach 1:
The patent applies segmentation by identifying and separately handling the electromotive force signal as a high occurrence-frequency signal that requires accurate detection. This signal is prioritized for higher sampling rates while other less critical signals use lower sampling rates, achieving precise electromotive force measurement without requiring the AD converter to operate at maximum speed for all signals.
Solution Approach 2:
The patent applies local quality by allocating different sampling frequencies to different signals based on their specific requirements. The electromotive force signal receives higher sampling frequency for accurate detection, while pump current and temperature signals use lower sampling frequencies, optimizing measurement precision where needed while controlling overall system 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
This approach enables quicker response times in gas detection with reduced costs and size, maintaining accuracy in detecting gas concentrations and oxygen pumping control, while simplifying computation processing.
Implementation Method 1
a detection cell for producing an electromotive force corresponding to a particular component contained in an object gas
Implementation Method 2
an oxygen pump cell for performing pumping in or pumping out of oxygen in accordance with pump current
Data Source
AI summary
In a sensor control apparatus of a gas detection system, a multiplexer having received an instruction from a digital computation section outputs analog signals in the order of, for example, “signal 1, signal 2, signal 1, signal 3, signal 1, signal 4.” By outputting the analog signals while classifying each of them as a high occurrence-frequency signal which is high in output frequency or a low occurrence-frequency signal which is low in output frequency, the multiplexer can increase the sampling frequency of signal (analog signal of Vs+-COM voltage) which is the high occurrence-frequency signal. The sensor control apparatus can increase the sampling frequency in AD conversion of signal to a digital value, while suppressing an increase in the cost of an AD conversion section.