Electrically Heated Catalyst for Particle Filter Regeneration
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Solution Overview
Problem
The regeneration of a particle filter in the underbody position of a vehicle is challenging due to the difficulty in reaching the required regeneration temperature shortly after starting the internal combustion engine, especially at cold temperatures, leading to increased emissions and potential misfiring.
Innovation Solution
An exhaust aftertreatment system with a close-coupled three-way catalytic converter and an electrically heatable three-way catalytic converter positioned downstream, combined with secondary air injection, allows for rapid and low-emission regeneration of the particle filter, independent of the engine load profile, using a secondary air system and lambda probes for precise oxygen management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a particle filter is installed in the underbody position of a vehicle, then it effectively captures soot particles from exhaust gas, but it cannot reach the required regeneration temperature shortly after engine start-up, especially at cold temperatures
Solution Approach 1:
The electric heater is activated before the particle filter needs regeneration to preheat the filter to the required temperature. This preliminary heating action enables the particle filter to reach regeneration temperature quickly after engine start-up or during cold operating conditions, resolving the contradiction between capturing soot particles and maintaining regeneration temperature.
2Productivity
If the particle filter is regenerated by thermal oxidation, then soot is removed from the filter, but additional components and control systems are required to achieve and maintain the necessary temperature
Solution Approach 1:
The particle filter regeneration system uses the vehicle's existing exhaust heat and electrical heating elements to achieve regeneration without requiring additional complex external heating systems. The system leverages available resources (exhaust gas heat and vehicle electrical system) to perform the regeneration function, reducing overall system complexity while maintaining high regeneration efficiency.
3Object-generated harmful factors
If the engine operates with stoichiometric combustion air ratio, then emission conversion is efficient, but there is insufficient excess oxygen available for particle filter regeneration
Solution Approach 1:
The electric heater preheats the particle filter before regeneration is initiated, creating favorable conditions for subsequent thermal oxidation. This preliminary heating action allows the system to maintain stoichiometric combustion for emission control while still achieving effective regeneration by providing the initial temperature boost needed for soot oxidation to proceed with the available oxygen.
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 solution enables efficient and rapid regeneration of the particle filter, reducing emissions and maintaining engine performance by ensuring the particle filter reaches the necessary temperature for soot oxidation, even at low operating conditions, thus complying with emission standards.
Implementation Method 1
an electrically heatable three-way catalytic converter positioned downstream, combined with secondary air injection, allows for rapid and low-emission regeneration of the particle filter
Implementation Method 2
The secondary air is used to exothermically convert unburned exhaust gas components, in particular unburned hydrocarbons, to heat the exhaust gas flow
Implementation Method 3
In order to thermally oxidize the soot retained in the Otto particle filter with oxygen, a sufficiently high temperature level in conjunction with the oxygen present at the same time in the exhaust system of the Otto engine is necessary
Data Source
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AI summary
The invention relates to an exhaust aftertreatment system for an internal combustion engine (10). The internal combustion engine (10) is connected to an exhaust system (20) via its exhaust outlet (16). In the exhaust system (20), in the direction of flow of exhaust gas from the internal combustion engine (10) through an exhaust channel (18) of the exhaust system (20), a three-way catalyst close to the engine (22), an electrically heated three-way catalyst (24) downstream of the three-way catalyst close to the engine (22), and further downstream a particulate filter (26) or a four-way catalyst (27) are arranged. Furthermore, the exhaust aftertreatment system includes a secondary air system (40) with a secondary air pump (42) and a secondary air line (46), which opens into the exhaust channel (18) at an inlet point (48) downstream of the engine-adjacent three-way catalyst (22) and upstream of the electrically heated three-way catalyst (24).The invention further relates to a method for regenerating a particulate filter (26) or the four-way catalytic converter (27) with such an exhaust aftertreatment system.