Parallel Catalytic Converters with Cross-Connection for Cold Start
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exhaust-gas aftertreatment arrangements for internal combustion engines face challenges in reducing pressure drop and emissions, especially at high engine loads, due to catalytic converters operating below optimal temperature, which is exacerbated by increased thermal mass when using multiple converters in parallel.
Innovation Solution
The arrangement of two parallel catalytic converters connected by a connection pipe allows for controlled heating of the secondary converter through a secondary exhaust gas flow when the outlet valve is closed, ensuring it reaches operating temperature quickly, and switching to dual converter operation at cold starts by using the venturi effect and thermal contact to manage flow and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If two or more catalytic converters are arranged in parallel to reduce pressure drop, then pressure drop is reduced, but thermal mass increases causing slower heating and higher emissions during cold start
Solution Approach 1:
The system divides the exhaust flow into two separate paths, each containing a catalytic converter (first and second catalytic converters). This segmentation allows independent control of each converter's thermal mass and flow characteristics, enabling the system to optimize for both low pressure drop and fast heating by managing each segment separately based on operating conditions.
Solution Approach 2:
The system dynamically switches between different operational modes: during cold start, the second catalytic converter is isolated to allow concentrated heating of the first converter; during normal operation, both converters are activated in parallel. This dynamic reconfiguration resolves the contradiction by adapting the system's thermal mass and flow distribution to match real-time temperature and pressure requirements.
2Stress or pressure
If the size of the catalytic converter is increased to reduce pressure drop, then pressure drop is reduced, but thermal mass increases causing slower heating
Solution Approach 1:
Instead of using a single large catalytic converter, the system segments the function across two smaller converters arranged in parallel. Each converter has reduced thermal mass compared to a single large unit, enabling faster heating while collectively providing the same or greater flow capacity to maintain low pressure drop.
Solution Approach 2:
The system performs preliminary heating action by concentrating exhaust flow through the first catalytic converter during cold start conditions. This preliminary action brings the first converter to operating temperature quickly, and subsequently both converters operate in parallel to maintain low pressure drop during normal conditions.
3Temperature
If catalytic converters are positioned close to exhaust ports to improve heating, then heating speed is improved, but pressure drop increases
Solution Approach 1:
The system positions the first catalytic converter close to the exhaust port for rapid heating, while the second catalytic converter is positioned downstream. This segmented arrangement allows the upstream converter to capture heat quickly during cold start, while the downstream converter provides additional flow capacity to offset pressure drop during normal operation.
Solution Approach 2:
The system dynamically adjusts which converter(s) are active based on temperature conditions. During cold start, only the first converter near the exhaust port is active to maximize heating efficiency. During normal operation, both converters are activated, allowing the system to tolerate the pressure drop from the first converter's proximity to the exhaust port while benefiting from the combined flow capacity of both units.
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 reduces emissions and pressure drop by ensuring the secondary converter is at optimal temperature when needed, improving engine performance and efficiency by varying the overall capacity based on engine conditions without additional sensors or complex controls.
Implementation Method 1
The connection pipe is arranged in thermal contact with the first catalytic converter
Implementation Method 2
The inlet of the first catalytic converter comprises a constriction having a diameter which is smaller than a diameter of adjacent portions of the inlet
Data Source
Figure 1a~2
Figure 3
AI summary
An exhaust-gas aftertreatment arrangement (100) for an internal combustion engine comprising a first catalytic converter (102), a second catalytic converter (104) arranged in parallel with the first catalytic converter, the first and second catalytic converters being arranged to receive exhaust gas from an engine, a connection pipe (112) fluidly connecting an outlet (114) of the second catalytic converter with an inlet (108) of the first catalytic converter, thereby allowing a flow of exhaust gas through the connection pipe, a connection pipe valve (113) configured to control a flow of exhaust gas through the connection pipe; and an outlet valve (116) arranged in the outlet of the second catalytic converter and downstream of the location of the connection pipe, wherein the outlet valve is configured to control a flow of exhaust gas through the second catalytic converter. There is also provided a method for controlling an exhaust-gas aftertreatment arrangement.