Exhaust Purification System Catalyst Temperature Estimation
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Solution Overview
Problem
The existing exhaust purification systems face challenges in accurately estimating catalyst temperatures, leading to poor controllability of exhaust pipe and post injections during catalyst regeneration processes, resulting in excessive temperature rises and increased fuel consumption, especially when the initial engine start temperature deviates from the actual temperature.
Innovation Solution
An exhaust purification system that includes a catalyst temperature estimating unit, pre-stop catalyst temperature storage, first and second exhaust temperature acquisition, intake air temperature acquisition, and an initial catalyst temperature setting unit to quickly reduce the error between actual and estimated catalyst temperatures by using pre-stop and start exhaust temperatures and intake air temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the initial catalyst temperature is set using a simple default value or without considering pre-stop conditions, then the device complexity is reduced, but the measurement precision of catalyst temperature estimation deteriorates, leading to poor controllability of injection processes
Solution Approach 1:
The system performs preliminary actions by storing the catalyst temperature and exhaust temperature immediately before engine stoppage. These pre-stored values are then used as initial temperatures for the subsequent engine start-up period, eliminating the need for complex real-time temperature measurement systems during cold start while maintaining accurate temperature estimation.
Solution Approach 2:
The patent uses pre-stored catalyst temperature and exhaust temperature as intermediary values to bridge the temperature estimation gap during engine start-up. Instead of directly measuring catalyst temperature during cold start (which is difficult), the system uses readily available exhaust temperature and pre-stored catalyst temperature as proxies, achieving accurate indirect temperature estimation.
2Productivity
If the catalyst temperature estimation error is large at engine start-up, then the ease of operation is improved by using simple initial temperature settings, but the productivity of the regeneration process deteriorates due to excessive temperature rises and increased fuel consumption
Solution Approach 1:
The system implements feedback by continuously monitoring exhaust temperature and using it to update the catalyst temperature estimation during engine start-up. The exhaust temperature sensor provides real-time feedback that allows the control system to adjust injection timing and quantity, optimizing the regeneration process while preventing excessive temperature rises.
Solution Approach 2:
By pre-storing the catalyst temperature before engine stoppage, the system has accurate initial temperature data ready before start-up begins. This preliminary preparation eliminates the need for trial-and-error injection control during cold start, allowing immediate optimization of the regeneration process and reducing fuel consumption.
3Loss of energy
If the exhaust pipe injection and post injection are controlled without accurate catalyst temperature data, then the device complexity is reduced, but the loss of energy increases due to excessive fuel injection and prolonged regeneration time
Solution Approach 1:
The patent uses exhaust temperature as an intermediary measurement that is easier to obtain than direct catalyst temperature. By correlating exhaust temperature with catalyst temperature through pre-stored data and thermal models, the system achieves accurate energy management for injection control without requiring complex direct catalyst temperature sensing, thereby reducing fuel consumption during regeneration.
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 system effectively reduces the error between actual and estimated catalyst temperatures at an early stage, improving the controllability of injection processes and reducing fuel consumption by accurately setting initial catalyst temperatures.
Implementation Method 1
The catalyst bed temperature estimation device executes a first bed temperature estimation process, estimating the bed temperature of the catalyst based on the quantity of heat supplied to the catalyst and takes into account whether the exhaust gas of the prescribed quantity, or more, flows within the catalyst. The catalyst bed temperature estimation device also executes a second bed temperature estimation process which estimates each catalyst bed temperature based on a thermal conduction model in which it is assumed that heat is emitted from the catalyst only to a downstream side of the catalyst.
Implementation Method 2
estimating the bed temperature of the catalyst based on the quantity of heat supplied to the catalyst
Implementation Method 3
an unburned fuel is supplied to an upstream-side oxidation catalyst by the post injection or the exhaust pipe injection to raise an exhaust temperature to an SOx desorption temperature
Implementation Method 4
When the exhaust gas is under a rich atmosphere, the NOx occlusion reduction type catalyst detoxifies the occluded NOx through reducing and purifying by hydrocarbon contained in the exhaust gas, and discharges the NOx.
Implementation Method 5
the NOx occlusion reduction type catalyst occludes the NOx contained in the exhaust gas. When the exhaust gas is under a rich atmosphere, the NOx occlusion reduction type catalyst detoxifies the occluded NOx
Data Source
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AI summary
Provided is an exhaust purification system including; a catalyst (31, 32) that is provided in an exhaust passage of an engine (10) to purify an exhaust gas; a catalyst temperature estimating unit (80) that estimates a temperature of the catalyst (31, 32) based on an initial temperature of the catalyst (31, 32) at the time of starting of the engine (10) and a caloric value of the catalyst which changes depending on an operating state of the internal combustion engine; and an initial catalyst temperature setting unit (100) that sets an initial temperature of the catalyst (31, 32) based on a catalyst temperature stored immediately before stopping the engine (10), a temperature of an exhaust gas flowing into the catalyst (31) which is stored immediately before stopping the engine (10), a temperature of an exhaust gas flowing into the catalyst (31) which is acquired at the time of starting the engine (10), and a temperature of air taken into the engine (10) which is acquired at the time of starting the engine (10).