Exhaust Gas Temperature Estimation Controller for Internal Combustion Engine
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Solution Overview
Problem
Existing methods for estimating exhaust gas temperature in internal combustion engines, such as using map data, face challenges in accuracy due to variations in ignition timing and EGR amount, leading to inefficiencies in fuel consumption and drivability issues, and existing methods like JP 5373952 B do not accurately account for heat radiation along the exhaust pipe, resulting in significant estimation errors.
Innovation Solution
A controller and control method that includes a driving condition detector, an outlet gas temperature calculator, a heat radiation amount calculator, and an exhaust gas temperature estimator, which separately calculate the exhaust gas temperature at the combustion chamber outlet and the temperature decrease due to heat radiation along the exhaust pipe, allowing for precise estimation at any position along the exhaust pipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If map data estimation method is used for exhaust gas temperature, then sensor cost is reduced, but estimation accuracy deteriorates when ignition timing and EGR amount change
Solution Approach 1:
The invention changes the parameters used for estimation from static map data (rotational speed and charging efficiency only) to dynamic parameters including ignition timing and EGR amount. The estimation calculator computes exhaust gas temperature based on these varying parameters, allowing accurate estimation across different operating conditions without requiring expensive sensors for each condition.
Solution Approach 2:
The invention transitions from static map-based estimation to dynamic real-time calculation. The estimation calculator continuously computes exhaust gas temperature based on current ignition timing and EGR amount, making the estimation adaptive to changing operating conditions rather than relying on pre-stored map data that becomes inaccurate when conditions change.
2Device complexity
If heat radiation along exhaust pipe is not considered in estimation, then calculation complexity is reduced, but estimation accuracy at positions distant from combustion chamber deteriorates
Solution Approach 1:
The invention segments the temperature estimation into two distinct components: (1) exhaust gas temperature at the combustion chamber outlet, and (2) temperature decrease due to heat radiation along the exhaust pipe. This segmentation allows each component to be calculated separately with appropriate methods, improving overall accuracy while keeping individual calculations manageable.
Solution Approach 2:
The invention introduces an intermediary calculation step to estimate the temperature decrease amount caused by heat radiation along the exhaust pipe. This intermediary value (temperature decrease amount) is then subtracted from the combustion chamber outlet temperature to obtain the final estimation at any exhaust pipe position, effectively bridging the gap between combustion chamber conditions and exhaust pipe 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 approach improves the accuracy of exhaust gas temperature estimation along the exhaust pipe, enhancing fuel efficiency and drivability by accurately accounting for heat radiation effects, thereby improving the precision of EGR control and reducing estimation errors.
Implementation Method 1
a heat radiation amount calculator that calculates a temperature decrease amount of the exhaust gas by heat radiation of an exhaust pipe from the outlet of the combustion chamber to an estimation position
Data Source
AI summary
To provide a controller and a control method for an internal combustion engine capable of estimating exhaust gas temperature at any estimation positions of the exhaust pipe with good accuracy by taking into consideration a temperature drop of exhaust gas by heat radiation of the exhaust pipe. A controller for an internal combustion engine is provided with an outlet gas temperature calculator that calculates an outlet gas temperature which is a temperature of exhaust gas at an outlet of a combustion chamber, based on the driving condition; a heat radiation amount calculator that calculates a temperature decrease amount of the exhaust gas by heat radiation of an exhaust pipe from the outlet of the combustion chamber to an estimation position; and an exhaust gas temperature estimation calculator that estimate an exhaust gas temperature at the estimation position by subtracting the temperature decrease amount from the outlet gas temperature.