Internal Combustion Engine Secondary-Air Valve for Exhaust Backflow
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Solution Overview
Problem
Existing internal combustion engines face challenges in effectively preventing excessive backflow of exhaust gas into the secondary air line during secondary air injection, particularly in turbocharged gasoline engines, which can lead to insufficient heating of exhaust aftertreatment elements and increased emissions.
Innovation Solution
A compact, passive valve element with rotationally symmetrical baffles is integrated into the cylinder head, providing a high first flow resistance for secondary air injection and a significantly higher second flow resistance against backflow, preventing exhaust gas ingress while allowing efficient secondary air injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a secondary air system is used to heat exhaust aftertreatment elements, then the heating efficiency is improved, but exhaust gas backflow into the secondary air line occurs causing system contamination
Solution Approach 1:
A check valve is introduced as an intermediary component in the secondary air line to prevent exhaust gas backflow while allowing secondary air to flow toward the exhaust aftertreatment element. The check valve acts as a mediator that permits forward flow (secondary air injection) but blocks reverse flow (exhaust gas contamination), thus resolving the contradiction between heating efficiency and system contamination.
Solution Approach 2:
The harmful backflow function is extracted from the secondary air system by isolating the secondary air line from the exhaust tract using a check valve. This separation allows the secondary air system to perform its heating function independently without being contaminated by exhaust gas, effectively removing the harmful interaction between the two systems.
2Reliability
If high-power secondary air pumps are used to prevent backflow, then backflow prevention is improved, but system complexity and energy consumption increase
Solution Approach 1:
The check valve utilizes the natural pressure differential between the secondary air injection system and the exhaust tract to automatically prevent backflow without requiring external power or complex control mechanisms. The valve opens when secondary air pressure exceeds exhaust pressure and closes when the reverse occurs, making the system self-regulating and eliminating the need for high-power pumps.
Solution Approach 2:
The active mechanical control system (high-power secondary air pump) is replaced with a passive mechanical component (check valve) that relies on fluid pressure differential rather than powered actuation. This substitution dramatically reduces system complexity and energy consumption while maintaining reliable backflow prevention.
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
The solution enables rapid heating of exhaust aftertreatment elements, reduces emissions, and avoids the need for high-power secondary air pumps, maintaining efficient operation with minimal backflow and reduced system complexity.
Implementation Method 1
the valve element has a first flow resistance for a direction of injection and a second flow resistance for an opposite direction of backflow, the second flow resistance being significantly greater than the first flow resistance
Implementation Method 2
a fuel, i.e., unburned hydrocarbons in the exhaust system, can react with oxygen from the secondary air, thereby burning the fuel, particularly with the release of heat
Implementation Method 3
a fuel, i.e., unburned hydrocarbons in the exhaust system, can react with oxygen from the secondary air, thereby burning the fuel, particularly with the release of heat
Data Source
Figure 1
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AI summary
The invention relates to an internal combustion engine (12), with an exhaust tract (20) through which exhaust gas from the internal combustion engine (12) can flow, and with a secondary air system (22) which has a secondary air conduit (24) through which air as secondary air can flow in an injection direction (26), as a result of which the secondary air flowing through the secondary air conduit (24) in the injection direction (26) can be introduced into the exhaust tract (20). A valve element (10) is provided which is arranged in the secondary air conduit (24) and which has a first flow resistance along the injection direction (26) and a second flow resistance, which is greater than the first flow resistance, along a backflow direction (28) opposed to the injection direction (26), as a result of which a backflow taking place in the backflow direction (28) can be at least limited. The valve element (10) has a plurality of rotationally symmetrical impact bodies (30) which are arranged consecutively along the injection direction (26) and are connected to one another. The valve element (10) is arranged in a length region (L) of the secondary air conduit (24), the length region (L) of which is limited by a structural element (14) of the internal combustion engine (12), which structural element is formed separately from the valve element (10).