Heater Control for Gas Sensor Dryness Estimation
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Solution Overview
Problem
Existing heater control systems for gas sensors in vehicles fail to accurately determine the presence of condensed water in the exhaust pipe, leading to improper timing of heater power supply, which can result in sensor element damage and inaccurate oxygen concentration detection.
Innovation Solution
A heater control device that calculates heat data based on engine and vehicle operating conditions to determine dryness inside the exhaust pipe and adjusts the power supply to the heater accordingly, ensuring proper protection and activation of the sensor element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heater power supply is controlled based on accumulated heat quantity to the catalyst, then the sensor element is protected from damage, but the power supply timing may be delayed until condensed water has already dried out
Solution Approach 1:
The patent replaces the mechanical/thermal measurement approach (accumulated heat quantity to catalyst) with an estimation approach using temperature sensors and calculation means. The system estimates exhaust pipe temperature and determines condensed water presence based on temperature comparisons, allowing earlier and more accurate heater power supply control without waiting for thermal accumulation at the catalyst location.
Solution Approach 2:
The patent introduces an intermediary estimation system that uses exhaust gas temperature and outside air temperature as intermediate parameters to determine the actual exhaust pipe temperature and condensed water presence. This intermediary approach allows indirect measurement of conditions at the sensor location without direct temperature sensing at that precise point.
2Reliability
If the heater power supply is controlled based on exhaust pipe temperature estimation using exhaust gas temperature and outside air temperature, then the sensor element protection is improved, but the estimation accuracy remains low due to varying correlation under different operating conditions
Solution Approach 1:
The patent applies dynamics by making the correlation between exhaust gas temperature and exhaust pipe temperature variable rather than fixed. The calculation means dynamically adjusts the correlation based on detected operating conditions (engine load, temperature, etc.), allowing accurate exhaust pipe temperature estimation across varying operating conditions without requiring multiple fixed correlation tables.
Solution Approach 2:
The patent changes parameters by using multiple operating condition parameters (engine load, temperature, etc.) to dynamically adjust the temperature correlation. Instead of using a single fixed correlation, the system modifies the correlation based on the current operating state, improving estimation accuracy across different conditions.
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 solution effectively prevents sensor element damage by ensuring timely and accurate power supply to the heater, enhancing oxygen concentration detection accuracy and reliability, thereby improving exhaust emission control.
Implementation Method 1
When the heater is energized to generate heat, a temperature of the sensor element rises and the sensor element is maintained at an active state
Implementation Method 2
when at cold startup of an engine, water vapor in the exhaust gas is condensed to form condensed water
Data Source
AI summary
An oxygen concentration sensor including the sensor element for detecting oxygen concentration in the exhaust gas and the heater for heating the sensor element is installed at the location downstream of a DPF. An ECU controls power supply to the heater to make the sensor element at a predetermined active state. The ECU calculates heat data corresponding to a heat budget in the exhaust pipe in close proximity to the sensor location part after the engine startup, based upon an operating condition of the engine and a driving condition of a vehicle and also makes a determination as to dryness inside the exhaust pipe based upon the heat data. In addition, the power supply to the heater is controlled based upon the result of the dryness determination.