Gas Sensor Startup Pump Control for Faster Gas Detection
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Solution Overview
Problem
Existing gas sensors take a long time to accurately detect specific gas concentrations due to the need to pump out oxygen present in the measurement chamber, which affects measurement accuracy and is exacerbated by stricter emission control regulations.
Innovation Solution
A gas sensor with a pump cell controller that executes a start-up time measurement pump control process to quickly remove oxygen by setting a higher target voltage, followed by a normal time process when oxygen concentration is stabilized, using a sensor element with oxygen-ion-conductive solid electrolyte layers and measurement electrodes to detect gas concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heater is energized to heat the sensor element to activate the solid electrolyte layers, then the sensor element becomes operational, but the light-off time becomes long due to the time required to pump out oxygen from the measurement chamber
Solution Approach 1:
The patent applies preliminary action by executing a start-up time measurement pump control process that actively pumps out oxygen from the measurement chamber before normal measurement begins. The controller performs this oxygen removal operation during the heating period, so that when the sensor reaches operating temperature, the measurement chamber is already free of excess oxygen, thereby shortening the light-off time without compromising sensor reliability
2Measurement precision
If oxygen is pumped out from the measurement chamber to improve measurement accuracy, then specific gas concentration detection becomes accurate, but the light-off time increases
Solution Approach 1:
The patent performs the oxygen pumping action in advance during the start-up phase, before normal measurement begins. The controller executes the start-up time measurement pump control process that removes oxygen from the measurement chamber while the heater is warming up the sensor element. This preliminary oxygen removal ensures measurement accuracy is achieved without extending the light-off time, as the oxygen pumping occurs concurrently with the heating process
Solution Approach 2:
The patent employs dynamic control by switching between different measurement pump control processes based on the operational state. The controller dynamically transitions from the start-up time measurement pump control process (which actively pumps out oxygen) to the normal time measurement pump control process (which maintains normal operation). This dynamic switching allows the system to optimize both light-off time and measurement precision by applying the appropriate control strategy at each stage
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 reduces the light-off time of the sensor element by efficiently pumping out oxygen, allowing for rapid and accurate detection of specific gas concentrations.
Implementation Method 1
a sensor element which includes an element body which includes an oxygen-ion-conductive solid electrolyte layer
Implementation Method 2
a measurement pump cell having an outer measurement electrode provided outside the element body to be in contact with the measurement-object gas, and an inner measurement electrode disposed in a measurement chamber of the measurement-object gas flow portion, the measurement pump cell being configured to pump out oxygen from surroundings of the inner measurement electrode to surroundings of the outer measurement electrode
Implementation Method 3
The heater heats the sensor element up to a temperature at which the solid electrolyte layers are activated, and keeps the temperature
Implementation Method 4
a measurement voltage detection sensor cell that detects a voltage for measurement across the reference electrode and the inner measurement electrode
Data Source
AI summary
A gas sensor includes a sensor element and a pump cell controller. During a normal operation time of the sensor element, the pump cell controller executes a normal time measurement pump control process of pumping out the oxygen in a measurement chamber by controlling a measurement pump cell so that voltage for measurement reaches a normal time target value. At the start-up time of the sensor element, the pump cell controller executes a start-up time measurement pump control process of pumping out the oxygen in the measurement chamber by controlling the measurement pump cell so that the voltage for measurement reaches a start-up time target value higher than the normal time target value. When determining that the oxygen concentration in the measurement chamber is stabilized, the pump cell controller makes switching from the start-up time measurement pump control process to the normal time measurement pump control process.