Particulate Matter Sensor Electrostatic Induction Ceramic Pad
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Solution Overview
Problem
Existing particulate matter sensors, particularly those used in diesel vehicles, face challenges in maintaining sensitivity and mechanical strength, leading to reduced sensing precision and difficulty in detecting particulate filter damage.
Innovation Solution
A particulate matter sensor unit is designed with an electrostatic induction type sensor portion, a ceramic protection pad, a heater electrode for particulate matter elimination, and a silicon-based sensor body, utilizing conductive paste bonding and high-temperature resistant materials like Pt, Mo, and W, to enhance strength and reduce production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a differential pressure sensor is used to sense exhaust gas collected by the particulate filter, then the sensor can detect pressure differences, but the sensing precision of particulate matter is lowered and it becomes difficult to detect filter damage
Solution Approach 1:
The patent replaces the mechanical differential pressure sensor with an electrostatic induction type sensor that detects particulate matter through electrical charge interactions. This substitution enables direct sensing of particulate matter properties rather than indirect pressure measurement, thereby improving measurement precision and reliability for filter damage detection
Solution Approach 2:
The patent changes the detection parameter from pressure differential to electrostatic charge interaction. By using an electrostatic induction type sensor, the system directly measures the electrical charge of particulate matter, which provides more precise sensing and better reliability for detecting filter conditions
2Ease of manufacture
If the sensor portion is made with a silicon wafer, then production cost is reduced and productivity is increased, but the mechanical strength of the sensor portion is insufficient
Solution Approach 1:
The patent creates a composite structure by bonding the silicon wafer sensor portion to a ceramic protection pad. This composite design combines the manufacturing advantages of silicon wafers with the mechanical strength of ceramic materials, achieving both ease of manufacture and sufficient strength
Solution Approach 2:
The patent introduces a conductive paste as an intermediary bonding material between the silicon wafer sensor portion and the ceramic protection pad. This intermediary enables reliable mechanical bonding while maintaining the electrical properties needed for sensor operation, thus preserving both manufacturing efficiency and structural strength
3Measurement precision
If particulate matter adheres to the sensor, then the sensor can detect particulate matter, but the sensitivity of the sensor decreases
Solution Approach 1:
The patent implements a heater electrode that periodically burns off and removes accumulated particulate matter from the sensor surface. This cleaning function restores sensor sensitivity by removing the adhered particulate matter that would otherwise interfere with detection, enabling the sensor to maintain its detection capability over time
Solution Approach 2:
The patent employs periodic heating cycles through the heater electrode to continuously clean the sensor surface. This periodic action removes accumulated particulate matter at regular intervals, preventing sensitivity degradation and maintaining reliable detection performance
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 improves sensor strength and sensitivity, reduces production costs, and increases productivity by using a silicon wafer-based sensor body and ceramic protection pad, effectively addressing the limitations of existing sensors.
Implementation Method 1
a sensor portion (110) of an electrostatic induction type that is reacted when a particulate matter having electric charge is passing a vicinity thereof
Implementation Method 2
a heater electrode (120) that is formed on the protection pad and is configured to burn the particulate matter that is disposed on the sensor portion to eliminate particulate matter
Data Source
AI summary
A particulate matter sensor unit may include a sensor portion of an electrostatic induction type that may be reacted when a particulate matter having electric charge may be passing the vicinity thereof, a protection pad that the sensor portion may be bonded on one side thereof through a conductive paste, an heater electrode that may be formed on the protection pad and burns the particulate matters that may be disposed on the sensor portion to eliminate them, and a sensor electrode that may be formed on the protection pad to transfer a signal that may be generated by the sensor portion to an outside.