Close-Coupled Particulate Filter and Electrically Heatable Catalyst
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Solution Overview
Problem
Existing exhaust gas aftertreatment systems for internal combustion engines face challenges in achieving consistent regeneration temperatures for particulate filters, especially during cold starts, and suffer from ageing issues with three-way catalytic converters, leading to increased back pressure and emissions.
Innovation Solution
An exhaust gas aftertreatment system with a close-coupled configuration of a particulate filter and an electrically heatable three-way catalytic converter, supplemented by a secondary air system to introduce oxygen and accelerate heating, and an uncoated particulate filter to prevent ageing, ensuring efficient regeneration and reduced back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a particulate filter is positioned in the underbody position downstream of the engine, then the filter can be saturated with soot during vehicle operation, but the regeneration temperature cannot be reached in certain operating situations leading to excessive back pressure
Solution Approach 1:
The patent introduces a secondary air injection system that adds oxygen in a different spatial dimension (directly into the exhaust stream at the particulate filter) rather than relying solely on the engine's primary air intake system. This allows regeneration to occur in operating conditions where the engine would normally operate at stoichiometric ratios without excess oxygen available.
Solution Approach 2:
The system changes the oxygen concentration parameter in the exhaust gas by injecting secondary air, enabling the oxidation of soot at temperatures that would otherwise be insufficient for regeneration. This parameter change allows regeneration to proceed in previously unusable operating ranges.
2Reliability
If ignition timing is retarded and the engine is adjusted toward lean to thermally oxidize soot, then regeneration can occur, but additional components are required and excess oxygen must be supplied
Solution Approach 1:
The system uses the engine's own secondary air injection capability, which is already part of the engine management system, to provide the oxygen needed for regeneration. This self-service approach avoids adding dedicated regeneration components while still achieving the necessary oxygen supply for soot oxidation.
3Object-generated harmful factors
If a three-way catalytic converter with catalytically active coating is used, then gaseous pollutants can be converted, but the coating exhibits pronounced ageing effects requiring an additional converter
Solution Approach 1:
The patent divides the exhaust aftertreatment function into two separate components: a particulate filter for soot removal and a three-way catalytic converter for gaseous pollutant conversion. By positioning the particulate filter first in close-coupled position, it protects the downstream catalytic converter from thermal ageing, extending its service life while maintaining effective gaseous pollutant conversion.
4Temperature
If a close-coupled positioning of the particulate filter is used, then higher exhaust gas temperatures facilitate heating to regeneration temperature, but the filter position must be optimized
Solution Approach 1:
The particulate filter is positioned in close-coupled position upstream of the three-way catalytic converter, allowing it to first receive the highest temperature exhaust gases directly from the engine. This preliminary exposure to high temperatures facilitates rapid heating to regeneration temperature before the gas cools further downstream.
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 configuration allows for rapid heating and regeneration of the particulate filter, reducing back pressure and emissions, enhancing the durability of the catalytic coating and improving the overall efficiency of the exhaust gas aftertreatment system.
Implementation Method 1
an electrically heatable three-way catalytic converter (26)
Implementation Method 2
electrically heating the electrically heatable three-way catalytic converter (26) to a light-off temperature
Implementation Method 3
Thermally oxidizing the soot trapped in the gasoline particulate filter requires a high enough temperature level in conjunction with the simultaneous presence of oxygen
Implementation Method 4
heating the particulate filter (24), the electrically heatable three-way catalytic converter (26) and the further three-way catalytic converter (28) using the exhaust-gas flow from the internal combustion engine (10)
Implementation Method 5
the unburned exhaust components reacting exothermally with the secondary air still in the exhaust duct and thus ensuring a heating of the exhaust gas
Implementation Method 6
a three-way catalytic converter, as the second emission-reducing component
Data Source
AI summary
The invention relates to an exhaust gas aftertreatment system for an internal combustion engine (10), in particular for an internal combustion engine (10) which is charged by means of a turbocharger (30) and spark-ignited by means of spark plugs (16). A particulate filter (24) and an electrically heatable three-way catalytic converter (26) downstream of the particulate filter (24) are arranged in a position close to the engine in an exhaust gas system (20) connected to an outlet (12) of the internal combustion engine (10). A further three-way catalytic converter (28) is arranged in the underbody position of the motor vehicle downstream of the electrically heatable catalytic converter (26). According to the invention, the electrically heatable three-way catalytic converter (26) is heated electrically after engine start, and the particulate filter (24), the electrically heatable three-way catalytic converter (26) and the further three-way catalytic converter are additionally heated by the exhaust gas flow from the internal combustion engine (10). The electric heating of the electrically heatable three-way catalytic converter (26) is switched off when the electrically heatable three-way catalytic converter (26) has reached its light-off temperature.