Exhaust Gas Cleaning System Dual Heating Strategy
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Solution Overview
Problem
Catalytic converters in internal combustion engines do not attain full functionality until they reach a certain temperature (light-off temperature), leading to incomplete pollutant conversion during cold starts, and existing methods for preheating are either slow or require high electrical power.
Innovation Solution
A method that combines electrical heating of the catalytic converter with internal combustion engine operation as an air pump, controlling valve overlap and throttle flap to draw air back into the combustion chamber or discharge it into the intake tract, achieving rapid and efficient heating by recirculating exhaust gases and optimizing heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If only electrical heating is used to preheat the catalytic converter, then the heating process is simple to control, but the heating speed is too slow to achieve light-off temperature before engine start
Solution Approach 1:
The patent combines electrical heating with internal combustion engine heating measures by controlling the engine to operate as an air pump before actual start, creating a dual heating system that achieves faster heating speeds while maintaining controllability
Solution Approach 2:
The internal combustion engine is operated as an air pump before the actual starting to preheat the catalytic converter, performing the heating action in advance to ensure light-off temperature is reached before pollutant conversion begins
2Temperature
If the internal combustion engine is operated as an air pump to accelerate heating, then the heat transfer to catalytic converter is improved, but the device complexity and control complexity increase
Solution Approach 1:
The internal combustion engine performs multiple functions: it operates as an air pump for heating the catalytic converter, and subsequently transitions to normal combustion mode, making the same device serve both heating and power generation purposes
Solution Approach 2:
The valve timing parameters are temporarily adjusted during the air pump operation phase to optimize heat transfer to the catalytic converter, then returned to normal settings for actual engine operation, allowing dynamic adaptation without permanent structural changes
3Loss of time
If high electrical power is used to heat the catalytic converter rapidly, then the light-off temperature is reached faster, but the risk of overheating and energy consumption increases
Solution Approach 1:
The patent merges electrical heating with internal combustion engine heating, distributing the heating task between two sources to reduce the electrical power requirement while achieving the same heating speed, thereby lowering energy consumption and overheating risk
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 method allows the catalytic converter to reach light-off temperature quickly, reducing pollutant emissions like NOx during cold starts, while allowing for high electrical power use without overheating, and efficiently heating both the support and heated catalytic converters.
Implementation Method 1
electrically heating the heated catalytic converter before the starting of the internal combustion engine
Implementation Method 2
operating the internal combustion engine, before the starting thereof, as an air pump... achieve particularly good heat transfer from the heated catalytic converter to the catalytic converter
Implementation Method 3
The catalytic converter is brought above the light-off temperature of the catalytic converter before the starting of the internal combustion engine by virtue of the internal combustion engine being controlled, during its air pump operating mode, such that air is drawn back into the combustion chamber and/or air is discharged into the intake tract
Data Source
AI summary
A method for operating an exhaust-gas purification system which is arranged in the exhaust system of an internal combustion engine, and an exhaust-gas purification system, are described. In the method, a combination of electrical catalytic converter heating measures with internal combustion engine catalytic converter heating measures is implemented, whereby particularly fast and inexpensive heating of a catalytic converter is achieved. The corresponding exhaust system preferably has, in an exhaust-gas flow direction, firstly a support catalytic converter and then a heated catalytic converter.