Exhaust Pipe Temperature Estimation for Sensor Heater Control
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Solution Overview
Problem
Existing exhaust pipe temperature estimation methods for internal combustion engines are inaccurate, leading to delayed sensor activation and increased harmful emissions, particularly in vehicles with idle stop functions, due to insufficient consideration of environmental conditions.
Innovation Solution
The method involves obtaining correction information based on exhaust pipe temperature changes, elapsed time, internal combustion engine temperature changes, and outdoor cooling degree changes to accurately estimate the restart-time exhaust pipe temperature, using this as an initial value for sensor heater control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor heater is activated early to prevent element cracking, then sensor element damage is avoided, but harmful emissions increase due to delayed sensor activation
Solution Approach 1:
The system dynamically adjusts the sensor heater activation decision based on estimated exhaust pipe temperature parameters. When temperature is high, heater activation is delayed to reduce emissions; when temperature is low, heater activation is triggered early to prevent element cracking from condensate water
Solution Approach 2:
The system uses feedback from multiple sensors (coolant temperature, intake air temperature, elapsed time since stop) to continuously update the exhaust pipe temperature estimation, which then feeds back into the heater control decision to optimize both sensor protection and emission reduction
2Device complexity
If simple temperature estimation is used to control sensor heater, then device complexity is reduced, but estimation accuracy decreases leading to improper heater control
Solution Approach 1:
The control device utilizes existing multi-functional sensors (coolant temperature sensor, intake air temperature sensor, timer) already present in the engine management system to perform exhaust pipe temperature estimation, avoiding additional dedicated sensors while improving estimation accuracy through multi-parameter integration
3Device complexity
If environmental conditions are not considered in temperature estimation, then estimation process is simplified, but estimation accuracy deteriorates especially during idle stop operations
Solution Approach 1:
The system pre-calculates and stores correction values for different environmental conditions (intake air temperature, coolant temperature, elapsed time) in lookup tables during system development. During operation, it quickly retrieves and applies the appropriate correction without complex real-time calculations, maintaining both simplicity and accuracy
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 proper and early activation of the exhaust gas sensor, reducing the risk of sensor damage and harmful emissions by accurately estimating the exhaust pipe temperature and controlling the sensor heater operation.
Implementation Method 1
the exhaust gas sensor is provided with a sensor heater for heating the sensor element
Implementation Method 2
heating the exhaust pipeline using high-temperature water heated by a combustion burner to evaporate the condensate water
Data Source
AI summary
Provided are a novel exhaust pipe temperature estimation device and a sensor heater control apparatus for an exhaust gas sensor using the same that accurately estimates an estimation exhaust pipe temperature when an internal combustion engine is stopped and restarted in response to a change of an environmental condition of the internal combustion engine and controls an operation of a sensor heater based on the estimated estimation exhaust pipe temperature. Thus, at least first correction information Tz based on a change of an exhaust pipe temperature and an elapsed time at stop, second correction information Ty based on a change of an internal combustion engine temperature at the stop of the internal combustion engine, and third correction information Tz based on a change of a cooling degree due to outdoor air during stop from the stop to restart are obtained, an estimation exhaust pipe temperature at the stop is corrected using at least one or more pieces of the correction information at restart of the internal combustion engine to estimate an estimation exhaust pipe temperature at the restart, and an estimation exhaust pipe temperature during an operation of the internal combustion engine thereafter is obtained using the estimation exhaust pipe temperature as an initial value, and further, a heating operation of a sensor heater is started when the estimation exhaust pipe temperature becomes equal to or higher than a predetermined value.