Exhaust Gas Recirculation Flap Valve Control
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Solution Overview
Problem
Existing exhaust gas recirculation systems are not suitable for low-pressure operation and lack temperature control, leading to insufficient controllability of recirculated exhaust gas flow, potential damage to downstream compressors due to condensation, and increased sooting of the heat exchanger.
Innovation Solution
An exhaust gas recirculation system with a heat exchanger having two separate strands that can flow in U-shape or parallel, a flap valve for controlling flow resistance, and a bypass line with a bypass valve to regulate exhaust gas temperature and quantity, ensuring efficient heat recovery and preventing condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a U-shaped heat exchanger is used with a flap valve to close the exhaust duct downstream of both branches, then heat recovery is enabled, but the system cannot be used for low-pressure operation due to insufficient flow gradient control
Solution Approach 1:
The exhaust gas recirculation duct is divided into two separate strands instead of using a U-shaped heat exchanger. This segmentation allows independent control of each strand, enabling the system to operate in low-pressure mode by adjusting the flap valve positions to create appropriate flow gradients in each strand separately.
Solution Approach 2:
The flap valve is designed with multiple positions (first position opening the exhaust duct, second position closing it downstream of both strands, third position closing it between the strands, fourth position throttling it) to dynamically adjust flow resistance. This dynamic control enables the system to adapt to different operating conditions including low-pressure operation and heat recovery modes.
2Quantity of substance
If the exhaust duct is closed downstream of both heat exchanger branches to increase flow resistance, then exhaust gas recirculation rate is sufficient, but temperature control of recirculated exhaust gas is lost leading to condensation and sooting
Solution Approach 1:
The system uses two separate strands instead of a U-shaped heat exchanger, allowing independent temperature and flow control of each strand. This enables selective closing or throttling of individual strands to maintain temperature control while achieving sufficient exhaust gas recirculation rates.
Solution Approach 2:
The flap valve can be positioned in four different states (open, closed downstream, closed between strands, throttled) to change flow parameters dynamically. By adjusting the flap position and selectively closing individual strands, the system maintains both sufficient recirculation quantity and appropriate temperature control to prevent condensation and sooting.
3Loss of energy
If the exhaust duct is closed in the region between the two strands to direct flow through one strand, then heat absorption is improved, but the system complexity increases with multiple valve positions
Solution Approach 1:
The single flap valve performs multiple functions by being positioned in four different states: opening the exhaust duct, closing it downstream of both strands, closing it between the strands for heat absorption, and throttling it for flow control. This multi-functionality achieves heat absorption improvement without requiring multiple separate valves, thus limiting the increase in system complexity.
4Loss of time
If a bypass line is added to allow hot exhaust gas to bypass the heat exchanger, then warm-up time is reduced, but the system complexity increases
Solution Approach 1:
The flap valve's first position opens the exhaust duct to allow hot exhaust gas to bypass the heat exchanger, reducing engine warm-up time. This dynamic positioning capability of the existing flap valve provides the bypass function without requiring a separate bypass valve or additional complex bypass system.
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 efficient temperature and quantity control of exhaust gas, reducing warm-up times, preventing condensation, and achieving high thermal energy recovery while minimizing component costs and sooting of the heat exchanger.
Implementation Method 1
The thermal energy is extracted from the exhaust gas via the exhaust gas recirculation system's heat exchanger
Implementation Method 2
A flap valve is arranged in the exhaust duct and can be adjusted between a first position, in which the exhaust duct is completely open and an opening of the heat exchanger is completely closed, and a second position, in which the exhaust duct is completely closed in the region of the heat exchanger
Data Source
Figure 1
AI summary
The present invention relates to an exhaust gas recirculation system for an internal combustion engine with an exhaust gas duct (10) of the internal combustion engine (14), an inlet duct (16) of the internal combustion engine (14), an exhaust gas recirculation duct (18) which branches off from the exhaust gas duct (10) and opens into the inlet duct (16), a heat exchanger (20) which is arranged in the exhaust gas recirculation duct (18), and two sections (24, 26) which are separate from one another, an exhaust gas recirculation valve (28) which is arranged at an outlet (27) of the heat exchanger (20), a flap valve (50) which is arranged in the exhaust gas duct (10) in such a way that the flap valve (50) releases the exhaust gas duct (10) in a first position, closes the exhaust gas duct (10) in the flow direction downstream of the two sections (24, 26) in a second position, closes the exhaust gas duct (10) in the region between the two sections (24, 26) in a third position, and throttles the exhaust gas duct (10) in a fourth position. In order to make a temperature regulation possible and to enable heat to be recovered from the exhaust gas in all circumstances, it is proposed that the heat exchanger (20) can be bypassed via a bypass line (34), the throughflow cross section of which can be regulated by means of a bypass valve (32), and which branches off from the exhaust gas duct (10) upstream of the flap valve (50). In addition, the invention relates to a method for regulating an exhaust gas recirculation system of this type.