Membrane Secondary Air Pump for Exhaust Pulse Synchronization
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Solution Overview
Problem
Existing secondary air systems in internal combustion engines, particularly during cold starts, struggle to efficiently reduce harmful exhaust gases due to sequential air injection caused by radial compressors, which cannot keep pace with pressure peaks from exhaust gas pulses, leading to incomplete pollutant oxidation and slow catalytic converter heating.
Innovation Solution
An internal combustion engine design incorporating a secondary air pump with a membrane and electrical actuator, utilizing exhaust gas pulses to generate a pulsating secondary air flow synchronized with exhaust gas pulses, enabling continuous and high-pressure secondary air injection upstream of the catalytic converter, thereby enhancing pollutant oxidation and catalytic converter heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a radial compressor is used to convey secondary air, then the device structure is simple, but the secondary air can only be blown in sequentially between exhaust gas pulses, resulting in incomplete pollutant oxidation
Solution Approach 1:
The patent employs a diaphragm pump with a membrane that dynamically responds to exhaust gas pressure pulses. The membrane is actuated by the pulsating exhaust gas flow, automatically synchronizing the secondary air injection with the exhaust gas pulses to achieve continuous injection throughout the entire exhaust stroke, eliminating the sequential injection limitation of radial compressors.
Solution Approach 2:
The secondary air pump system uses the exhaust gas pulses themselves to drive the membrane pump. The exhaust gas pressure directly actuates the membrane without requiring an external motor or compressor, making the system self-powered and enabling continuous operation synchronized with the engine's exhaust cycles.
2Temperature
If a radial compressor is used to convey secondary air, then the device complexity is low, but the energy requirement is high and heat output is insufficient for rapid catalytic converter heating
Solution Approach 1:
The patent converts the waste heat energy in the exhaust gas into useful work by using the hot exhaust gas pulses to directly drive the membrane pump. This not only powers the secondary air injection system without external energy input but also ensures the secondary air is pre-heated, improving the heating efficiency of the catalytic converter when the air is injected.
Solution Approach 2:
The patent replaces the traditional motor-driven radial compressor with a pneumatic membrane pump system. The mechanical work previously required from an electric motor is now provided by the pressure energy of the exhaust gas itself, eliminating the need for additional energy input while maintaining or improving the heating performance.
3Productivity
If secondary air is injected sequentially between exhaust gas pulses, then the device operation is simple, but the pollutant oxidation efficiency is reduced
Solution Approach 1:
The membrane pump creates a dynamic injection system that adapts to the exhaust gas pulse frequency and amplitude. The membrane automatically oscillates at the same frequency as the exhaust pulses, creating continuous secondary air injection that maintains high oxidation efficiency without requiring complex control mechanisms or multiple injectors.
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 design achieves a more homogeneous exhaust gas after-treatment with reduced pollutant concentrations and rapid catalytic converter heating, ensuring effective pollutant reduction and efficient energy use during cold starts.
Implementation Method 1
The membrane is arranged within the pump chamber and divides the pump chamber, in particular in a gas-tight manner, into a secondary air chamber and an exhaust gas chamber
Implementation Method 2
In particular, the exhaust gases flowing out of the combustion chamber in pulses lead to an unsteady actuation of the membrane. This actuation of the membrane in turn leads to a pulsating secondary air flow.
Implementation Method 3
By actuating the membrane, the secondary air is sucked into the secondary air space and then expelled from it.
Implementation Method 4
The secondary air system is preferably provided for a cold start of the internal combustion engine in order to effect post-oxidation of unburned hydrocarbons present in the exhaust system, which are produced during a cold start, upstream of the catalytic converter.
Implementation Method 5
The resulting heat also heats up the catalytic converter and shortens the time until lambda control starts.
Data Source
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AI summary
The present invention relates to an internal combustion engine, comprising a primary air system (1), for providing fresh air, and a secondary air system (2), which is designed to branch off secondary air from the primary air system (1) and to inject same into an exhaust duct (7), wherein the secondary air system (2) has a secondary air pump (5) for conveying the secondary air, wherein the secondary air pump (5) comprises: a pump chamber (51), a diaphragm (52), which is arranged in the pump chamber (51) and divides the pump chamber (51) into a secondary air chamber (51a) and an exhaust gas chamber (51b), an electrically actuatable actuator (53), which is connected to the diaphragm (52) and which is configured to actuate the diaphragm (52), and an exhaust gas line (54), which connects the exhaust gas chamber (51b) to the exhaust gas duct (7) of the internal combustion engine (10).