Particulate Matter Sensor Heater Resistance Measurement
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Solution Overview
Problem
Existing particulate matter sensors cannot accurately measure the temperature of the heater due to the inability to isolate the heater resistance from the total resistance, which includes lead resistance, leading to errors in temperature calculation and increased production costs when using separate temperature sensors.
Innovation Solution
A particulate matter sensor design that includes a sensing line connected to the heater leads to measure the resistance of the leads, allowing the control circuit to calculate the lead resistance and subtract it from the total resistance to derive the heater resistance, enabling precise temperature calculation of the heater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate temperature sensor is provided to measure the temperature of the heater, then the temperature measurement accuracy is improved, but the production cost increases
Solution Approach 1:
The heater leads serve dual purposes: delivering electrical current to the heater and simultaneously serving as temperature sensing elements through resistance measurement. The control circuit measures the resistance of the heater leads to determine temperature, eliminating the need for separate temperature sensors and reducing production costs while maintaining measurement capability.
Solution Approach 2:
The heater leads are designed to perform multiple functions: electrical conduction to the heater and temperature sensing through resistance measurement. This multi-functionality allows the same component to serve both current delivery and temperature measurement purposes, avoiding additional cost for separate sensors.
2Device complexity
If the total resistance (heater resistance + lead resistance) is used to calculate heater temperature, then the measurement system is simplified, but the temperature calculation accuracy deteriorates due to lead resistance errors
Solution Approach 1:
The control circuit extracts and removes the lead resistance component from the total resistance measurement. By measuring the resistance of the heater leads separately and subtracting this value from the total resistance, the circuit isolates the heater resistance, eliminating the error introduced by lead resistance variations while maintaining system simplicity.
Solution Approach 2:
The control circuit acts as an intermediary that processes the resistance measurements to separate the lead resistance from the heater resistance. Through calculated subtraction of lead resistance from total resistance, the circuit derives the pure heater resistance for accurate temperature calculation, mediating between the simplified measurement approach and accurate temperature determination.
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 allows for accurate temperature measurement of the heater without a special temperature sensor, reducing production costs and improving the accuracy of particulate matter measurement and heating control.
Implementation Method 1
a heater which heats the deposition portion
Implementation Method 2
a sensing line connected to at least one of the heater leads to measure a resistance of the one of the heater leads
Implementation Method 3
voltage is applied between the electrodes of the particulate matter sensor. This causes particulate matter emissions to be converged by electrostatic force, so that electrical current flows between the electrodes
Implementation Method 4
the measuring mode is changed to the burning mode to actuate the heater to burn off the accumulated particulate matter
Data Source
AI summary
A particulate matter sensor and a particulate matter sensing system using such a sensor are provided which are capable of being produced at decreased cost and accurately measuring the temperature of a heater. The particulate matter sensor includes a deposition portion on which particulate matter contained in exhaust gas is accumulated, a pair of electrodes which are disposed on the deposition portion and separate from each other, a heater which heats the deposition portion, and a pair of heater leads which form a path through which electrical current is delivered to the heater. A sensing line is connected to at least one of the heater leads to measure a resistance of the heater lead.