Catalyst Temperature Estimation Using Inlet Gas Weighted Averaging
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Solution Overview
Problem
Conventional exhaust gas purifying apparatuses for internal combustion engines fail to accurately estimate catalyst temperatures due to the lack of consideration for inlet gas temperature influences, leading to inaccuracies in temperature estimation.
Innovation Solution
The apparatus includes means to obtain and consider both inlet and outlet gas temperatures, using weighted averages and temperature correction coefficients adjusted based on the operational state of the engine to accurately estimate catalyst temperatures, with separate corrections for different regions of the catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional catalyst temperature estimation means is used that only considers catalyst temperature and outlet gas temperature, then the device complexity is reduced, but the measurement precision of catalyst temperature is insufficient
Solution Approach 1:
The system calculates a correction amount based on the deviation between the estimated outlet gas temperature and the actual measured outlet gas temperature, then applies this correction to improve the accuracy of catalyst temperature estimation. This feedback mechanism allows the system to self-correct and improve precision without adding complex hardware.
Solution Approach 2:
The invention replaces physical temperature sensors at multiple catalyst locations with a computational estimation system that uses mathematical models and correction algorithms. This substitution of mechanical measurement devices with computational methods achieves high measurement precision while maintaining simple device structure.
2Reliability
If inlet gas temperature is not considered in the estimation, then the calculation process is simplified, but the reliability of temperature estimation deteriorates
Solution Approach 1:
The system incorporates inlet gas temperature as an additional parameter in the outlet gas temperature estimation calculation, along with catalyst temperature and degree of influence. This parameter expansion improves estimation reliability by accounting for all significant thermal factors affecting the catalyst, while the calculation remains computationally manageable.
3Measurement precision
If a single temperature estimation model is used for the entire catalyst, then the device complexity is reduced, but the measurement precision for different catalyst regions is insufficient
Solution Approach 1:
The catalyst is divided into multiple regions (front, middle, rear), and the system calculates correction amounts separately for each region based on their specific thermal characteristics and degree of influence. This segmentation allows precise temperature estimation for each catalyst region while using a unified estimation framework, balancing precision and system simplicity.
Data Source
AI summary
The present invention has an object to provide an exhaust gas purifying apparatus for an internal combustion engine capable of obtaining accurate temperature information relating to a catalyst placed in an exhaust passage of the internal combustion engine. The degree of influence emthc of a catalyst inlet gas temperature and catalyst rear end temperature ethuf[end] is calculated (Step 102). An estimated value ethco of an outlet gas temperature is calculated by weighted averaging the inlet gas temperature and the catalyst rear end temperature ethuf[end] considering the degree of influence emthc (Step 104). A temperature correction coefficient ekthuf[x] for each region of the catalyst is calculated as a function f(emthc) of the degree of influence emthc (Step 108). A deviation between the outlet gas temperature estimated value ethco and a measured value of the outlet gas temperature is multiplied by the temperature correction coefficient ekthuf[x] to calculate an estimated value correction amount ecthuf[x] (Step 110). The estimated value correction amount ecthuf[x] is added to a catalyst temperature estimated value (Step 114).