Particulate Matter Sensor Self-Diagnosis via Heater Bias
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional particulate matter sensors face challenges in self-diagnosis due to the difficulty in distinguishing between a 'clean' sensor and fault conditions like open circuits caused by damage or disconnection, which can lead to increased manufacturing costs and time with the implementation of bias resistors.
Innovation Solution
A particulate matter sensor design incorporating ionic conductive materials with temperature-dependent impedance, allowing for diagnostic capabilities while minimizing manufacturing time and cost by integrating the ionic conductive material with the sensing electrodes and heater to detect fault conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias resistor is added to enable self-diagnosis, then diagnostic capability is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The heater element is made dual-functional by designing it to serve both as a heating component for soot oxidation and as a bias resistor for electrical continuity and self-diagnosis. This multi-functionality eliminates the need for a separate bias resistor, reducing device complexity while maintaining diagnostic capability through monitoring of heater resistance changes
Solution Approach 2:
The patent combines the heater and bias resistor functions into a single component. The heater element is electrically connected between the two sensing electrodes, merging the thermal function (soot oxidation) and electrical function (bias resistance for diagnosis) into one integrated structure, thereby simplifying the overall sensor design
2Reliability
If a separate sintering process is added for the bias resistor, then diagnostic capability is improved, but manufacturing time increases
Solution Approach 1:
The manufacturing process is simplified by combining the heater fabrication and sintering steps with the existing sensor element production. Since the heater is formed as part of the sensor element structure using the same ceramic materials and sintering process, there is no need for a separate sintering step, thus maintaining productivity while achieving diagnostic capability
Solution Approach 2:
The heater element is designed to fulfill multiple roles (heating and bias resistance) within the same manufacturing process, eliminating the need for additional processing steps that would be required if a separate bias resistor component were used
3Measurement precision
If the sensor is designed as a normally open circuit, then soot detection accuracy is improved, but fault detection difficulty increases
Solution Approach 1:
The system implements feedback by continuously monitoring the electrical resistance of the heater element. Since the heater serves as the bias resistor, any change in its resistance value provides feedback about the operational status. The control unit compares the measured resistance against expected values to detect faults such as open circuits or short circuits, enabling easy fault detection while maintaining the normally open circuit design for accurate soot measurement
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 effective self-diagnosis and fault detection without the need for additional sintering processes, reducing manufacturing costs and time while maintaining accurate particulate matter measurement and sensor functionality.
Implementation Method 1
An ionic conductive material is in electrical communication with the first sensing electrode and the second sensing electrode
Implementation Method 2
Because the soot particles are electrically conductive, the conductivity between the electrodes increases
Data Source
AI summary
A particulate matter sensor includes a first sensing electrode and a second sensing electrode spaced away from the first sensing electrode such that an electrode gap is formed between the first sensing electrode and the second sensing electrode upon which particulate matter is collected, thereby changing conductance between the first sensing electrode and the second sensing electrode. An ionic conductive material is in electrical communication with the first sensing electrode and the second sensing electrode.