Particulate Matter Sensor Bias Voltage Accumulation
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Solution Overview
Problem
Existing particulate matter sensors for vehicle exhaust gas face issues such as increased costs due to the use of expensive platinum electrodes and inefficient particulate matter accumulation, leading to prolonged signal generation times and noise interference from foreign materials.
Innovation Solution
The sensor employs a bias voltage supplied through bias electrodes made of platinum, which are strategically positioned between ground electrodes to enhance particulate matter accumulation, while using molybdenum for measurement and ground electrodes to reduce costs, and incorporates a protective tube with inclined introduction holes to concentrate exhaust gas flow and prevent noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If platinum electrodes are used for measurement and ground electrodes to ensure reliability and reduce noise, then measurement precision and reliability are improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent applies different material qualities to different functional zones: platinum is used only for the bias electrode where electrical stability is critical, while molybdenum is used for measurement and ground electrodes where high conductivity suffices. This localized differentiation maintains measurement reliability while reducing overall platinum consumption and manufacturing cost.
2Measurement precision
If measurement electrode and ground electrode are directly exposed to exhaust gas to enable particulate matter accumulation, then measurement function is achieved, but noise from foreign materials increases and reliability decreases
Solution Approach 1:
The patent introduces a protective tube as an intermediary component that physically isolates the electrodes from foreign materials in the exhaust gas. The tube allows exhaust gas to pass through while blocking solid particles and contaminants, enabling the electrodes to accumulate particulate matter for measurement without direct exposure to harmful foreign materials that would cause noise and reliability issues.
3Reliability
If sensing unit is placed inside protective tube to prevent foreign material exposure, then reliability is improved, but exhaust gas flow to sensing unit is reduced and measurement efficiency decreases
Solution Approach 1:
The protective tube is designed with multiple introduction holes distributed along its length, creating a porous-like structure that allows exhaust gas to flow through while filtering out large foreign materials. This configuration maintains reliable protection of the sensing unit while ensuring adequate exhaust gas flow reaches the measurement electrode for efficient particulate matter accumulation and measurement.
4Measurement precision
If bias voltage is applied to increase particulate matter accumulation, then measurement precision is improved, but energy consumption increases
Solution Approach 1:
The patent optimizes the bias voltage parameter to achieve sufficient particulate matter accumulation without excessive energy consumption. By carefully selecting the bias voltage level and applying it only during the accumulation phase rather than continuously, the system achieves improved measurement precision while minimizing energy usage through parameter optimization and temporal control.
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 configuration increases the accumulation of particulate matter, reduces signal generation time, and lowers sensor costs by minimizing platinum usage, while effectively filtering foreign materials and improving measurement accuracy.
Implementation Method 1
a bias voltage supplied to form an electric field to increase an accumulated amount of particulate matters at a sensing unit
Data Source
AI summary
A sensor for measuring particulate matters is supplied with a bias voltage to form an electric field to increase an accumulated amount of particulate matters at a sensing unit. The sensor includes a sensing unit in which measurement electrodes and ground electrodes are disposed to alternate with one another in a housing fixed to an exhaust pipe. The measurement electrodes are electrically connected to one another, and the ground electrodes are electrically connected to one another. Bias electrodes are disposed between the ground electrodes to supply the bias voltage to the sensing unit. The bias electrodes are electrically connected to one other.