Air-Fuel Ratio Sensor Heating Control via Condensed Water Mass Computation
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Solution Overview
Problem
Existing control devices for internal combustion engines fail to accurately determine the mass of condensed water in exhaust pipes, leading to premature sensor element heating or delayed heating, which can cause sensor element cracks and reduced exhaust performance.
Innovation Solution
A control device that computes the rate of change of condensed water mass based on saturated water vapor pressure and water vapor partial pressure, and updates the mass of condensed water by considering the heat received by the condensed water, to determine whether to perform heating control for the air-fuel ratio sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heater is started earlier based on simple condensed water computation, then sensor element heating control is performed, but sensor element cracks occur due to immersion in water
Solution Approach 1:
The invention changes the parameters used for condensed water mass computation from simple relative wall temperature and exhaust gas mass flow rate to include saturated water vapor pressure, water vapor partial pressure, and heat transfer considerations. This parameter transformation enables accurate determination of condensation and evaporation states, preventing premature heater activation that would cause sensor element cracks.
Solution Approach 2:
The invention implements feedback control by continuously computing condensed water mass based on thermodynamic parameters (saturated water vapor pressure, water vapor partial pressure) and heat transfer conditions. The computation results feed back to the heater control decision, enabling dynamic adjustment of heating control timing to prevent sensor element damage while maintaining accuracy.
2Reliability
If the heater is started later based on simple condensed water computation, then sensor element cracks are prevented, but air-fuel ratio control accuracy decreases
Solution Approach 1:
By transforming the computation parameters to include saturated water vapor pressure, water vapor partial pressure, and heat transfer rate, the invention achieves accurate condensed water mass determination. This enables optimal timing for heater activation that maintains air-fuel ratio control accuracy while preventing sensor element damage.
Solution Approach 2:
The invention replaces simple empirical computation methods with thermodynamic-based computation involving vapor pressure relationships and heat transfer analysis. This substitution enables precise prediction of condensation and evaporation processes, allowing optimal heater control timing that maintains both sensor integrity and control accuracy.
3Device complexity
If condensed water mass is computed based only on relative wall temperature and exhaust gas mass flow rate, then computation is simple, but accuracy is insufficient during evaporation process
Solution Approach 1:
The invention transforms the computation from using only relative wall temperature and exhaust gas mass flow rate to incorporating saturated water vapor pressure, water vapor partial pressure, and heat transfer rate. This parameter transformation significantly improves computation accuracy during the evaporation process while maintaining manageable complexity through systematic calculation methods.
Solution Approach 2:
The invention replaces simple empirical computation with thermodynamic-based computation involving vapor pressure relationships and heat transfer analysis. This substitution provides accurate condensed water mass determination during evaporation processes while using systematic calculation approaches that maintain computational efficiency.
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 computation of condensed water mass and timely heating control, preventing sensor element cracks and maintaining exhaust performance by ensuring precise air-fuel ratio control.
Implementation Method 1
computes the rate of change of condensed water mass in an exhaust pipe based on the saturated water vapor pressure and the water vapor partial pressure of exhaust gas
Implementation Method 2
computes the rate of change of evaporation mass in the exhaust pipe based on the amount of heat which the condensed water in the exhaust pipe receives
Implementation Method 3
computes the rate of change of evaporation mass in the exhaust pipe based on the amount of heat which the condensed water in the exhaust pipe receives
Data Source
AI summary
Control device of an internal combustion engine that determines whether or not to perform sensor element heating control of an air-fuel ratio sensor with high accuracy based on the mass of condensed water in an exhaust pipe. The control device computes the rate of change of condensed water mass in an exhaust pipe based on the saturated water vapor pressure and the water vapor partial pressure of exhaust gas, and computes the rate of change of evaporation mass in the exhaust pipe based on the amount of heat which the condensed water receives in the exhaust pipe. The control device updates the mass of condensed water based on the rate of change of condensed water mass and the rate of change of evaporation mass, and determines whether or not to perform heating control by a heating controlling unit based on the updated mass of condensed water.