Recirculation Line Routing for Exhaust Gas Recirculation
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Solution Overview
Problem
High-pressure exhaust gas recirculation in internal combustion engines is limited by the need for additional components and increased fuel consumption due to a negative pressure differential at low rotational speeds, and the charge air cooler reduces the driving pressure gradient, limiting its application to higher speeds.
Innovation Solution
A driving device with a recirculation line that allows exhaust gases to be introduced into the feed line either before or after the charge air cooler, using a bypass line and a shut-off and directional control device to manage the recirculation based on pressure conditions, eliminating the need for additional components and optimizing thermal efficiency and quietness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-pressure exhaust gas recirculation is implemented, then thermal efficiency is improved, but additional delivery units are required at low rotational speeds
Solution Approach 1:
The patent implements a dynamically switchable recirculation system with two separate recirculation lines: a first recirculation line for high-pressure exhaust gas recirculation (when discharge line pressure exceeds feed line pressure) and a second recirculation line for low-pressure exhaust gas recirculation (when feed line pressure exceeds discharge line pressure). The system automatically switches between high-pressure and low-pressure recirculation modes based on real-time pressure differential conditions, eliminating the need for additional delivery units while maintaining thermal efficiency across all operating ranges.
Solution Approach 2:
The patent changes the pressure parameter condition for exhaust gas recirculation by introducing a bypass line that allows exhaust gas to bypass the charge air cooler under specific pressure conditions. When the pressure differential is negative, the system switches to low-pressure recirculation mode where exhaust gas bypasses the charge air cooler, avoiding the need for additional delivery units while maintaining effective exhaust gas recirculation.
2Productivity
If exhaust gas is introduced upstream of the charge air cooler, then recirculation effectiveness is improved, but the driving pressure gradient is reduced
Solution Approach 1:
The patent implements dynamic routing of exhaust gas through either the first recirculation line (upstream of charge air cooler) or the second recirculation line (downstream of charge air cooler) based on the pressure differential between discharge and feed lines. When pressure conditions favor high-pressure recirculation, exhaust gas is routed upstream to maximize recirculation effectiveness. When pressure conditions are unfavorable, the system switches to downstream routing to preserve the driving pressure gradient, thus dynamically optimizing both recirculation effectiveness and pressure gradient maintenance.
Solution Approach 2:
The patent introduces a bypass line as an intermediary pathway that allows exhaust gas to bypass the charge air cooler when pressure conditions are unfavorable for high-pressure recirculation. This intermediary route maintains the driving pressure gradient by avoiding the charge air cooler's pressure drop, while still achieving effective exhaust gas recirculation through the alternative pathway.
3Device complexity
If a single recirculation line is used, then device complexity is reduced, but the rotational speed range for effective recirculation is limited
Solution Approach 1:
The patent segments the exhaust gas recirculation system into two distinct recirculation lines: a first recirculation line for high-pressure recirculation (effective at higher rotational speeds when discharge line pressure exceeds feed line pressure) and a second recirculation line for low-pressure recirculation (effective at lower rotational speeds when feed line pressure exceeds discharge line pressure). This segmentation allows the system to adapt to different rotational speed ranges and pressure conditions, expanding the overall operational range while maintaining relatively simple device complexity.
4Use of energy by moving object
If exhaust gas recirculation is employed at high rotational speeds, then thermal efficiency is improved, but fuel consumption increases
Solution Approach 1:
The patent changes the recirculation pressure parameter by switching between high-pressure and low-pressure recirculation modes based on operating conditions. At high rotational speeds where thermal efficiency improvement is most beneficial, the system employs high-pressure recirculation upstream of the charge air cooler to maximize thermal efficiency gains. The system optimizes the balance between thermal efficiency improvement and fuel consumption by selectively activating recirculation modes based on real-time pressure and operational conditions.
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
Enables exhaust gas recirculation across a wider rotational speed range, improving thermal efficiency and reducing fuel consumption by adjusting the recirculation point based on pressure conditions, while maintaining the benefits of high-pressure exhaust gas recirculation without additional components.
Implementation Method 1
a charge air cooler arranged in the feed line for cooling the combustion air
Implementation Method 2
a positive pressure gradient is necessary. The pressure of the exhaust gas in the discharge line before the exhaust gas turbine has to be greater than the pressure of the combustion air or of the mixture of combustion air and recirculated exhaust gas in the feed line
Data Source
AI summary
A driving device for driving a vehicle includes an internal combustion engine, a feed line for feeding combustion air to the internal combustion engine, a discharge line for discharging exhaust gases from the internal combustion engine, a charge air cooler that is arranged in the feed line for cooling the combustion air, and a recirculation line branching off the discharge line for recirculating the exhaust gas from the discharge line into the feed line. The recirculation line includes a bypass line that the exhaust gas can be fed to the internal combustion engine through the charge air cooler and/or bypassing the charge air cooler.