Engine Control Device for Exhaust Temperature Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine systems with variable compression or expansion ratios face challenges in accurately diagnosing the state of exhaust system components, such as catalysts and sensors, due to changes in combustion and exhaust gas temperature, which affect the accuracy of on-board diagnosis.
Innovation Solution
A control device that acquires and estimates compression or expansion ratios, and uses these parameters to estimate the temperature of exhaust gases or components like catalysts, allowing for improved on-board diagnosis by maintaining constant ratios during diagnosis and controlling engine conditions to optimize temperature ranges for accurate determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compression ratio or expansion ratio is changed in an engine, then the engine performance and efficiency are improved, but the temperature of exhaust gases and catalyst changes, which deteriorates the accuracy of on-board diagnosis
Solution Approach 1:
The invention changes the parameter being measured from absolute temperature to temperature change rate (dT/dt). By monitoring how quickly temperature changes rather than the absolute temperature value, the system can accurately diagnose component states even when the base temperature varies due to compression ratio or expansion ratio changes. This parameter transformation allows diagnosis to proceed under varying engine conditions.
Solution Approach 2:
The invention replaces direct temperature measurement with a calculation-based approach using temperature change rate. Instead of relying on temperature sensors that measure absolute temperature, the system uses the relationship between temperature change rate and component state, substituting direct measurement with a derived parameter that is less sensitive to operating condition variations.
2Quantity of substance
If the catalyst temperature increases, then the oxygen storage amount increases, but the diagnosis accuracy deteriorates when temperature is not considered
Solution Approach 1:
The invention transforms the diagnostic parameter from oxygen storage amount (which varies with temperature) to temperature change rate during rich air-fuel ratio operation. By monitoring how rapidly temperature increases when rich mixture is supplied, the system can determine catalyst deterioration state independently of the absolute oxygen storage amount, which fluctuates with catalyst temperature and compression ratio settings.
Solution Approach 2:
The system uses feedback from temperature change rate measurements to determine catalyst state. By continuously monitoring the temperature change rate during controlled rich operation and comparing it against reference values, the system adjusts its diagnosis of catalyst deterioration, accounting for variations in oxygen storage capacity due to temperature and compression ratio changes.
3Adaptability or versatility
If air-fuel ratio is changed for catalyst deterioration determination, then the oxygen storage amount changes, but the diagnosis accuracy is insufficient without temperature correction
Solution Approach 1:
The invention changes the diagnostic parameter from oxygen storage amount to temperature change rate during rich air-fuel ratio operation. When the air-fuel ratio is switched to rich, the catalyst temperature increases at a rate proportional to the oxygen storage amount. By measuring this temperature change rate rather than trying to measure oxygen storage directly, the system achieves accurate deterioration determination that is independent of absolute temperature and compression ratio variations.
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 enhances the accuracy of on-board diagnosis by stabilizing engine conditions and temperature ranges, ensuring precise determination of component states and improving diagnostic accuracy.
Implementation Method 1
a temperature estimation part which estimates a temperature of exhaust gases or a component based on the compression ratio or the expansion ratio
Data Source
AI summary
A control device applied to a system having an engine configured such that an expansion ratio can be changed is characterized to comprise an expansion ratio acquisition part for acquiring the expansion ratio, and a temperature estimation part for estimating a temperature of an exhaust gas discharged from the engine or a member positioned in a passage for the exhaust gas.