Silencer Wall Section as Oscillating Membrane for Active Sound Control
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Solution Overview
Problem
Existing muffler designs for internal combustion engines are costly and lack a compact design, particularly in active silencers that utilize electroacoustic converters, which require additional membranes and complex protection measures against exhaust gases.
Innovation Solution
The use of an oscillatable wall section of a muffler housing as a membrane excited by an actuator to generate pressure pulsations, eliminating the need for an additional membrane and reducing manufacturing costs, with the wall section designed for optimal vibration and potentially having reduced thickness or different materials for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complete electroacoustic transducer with cage, actuator and membrane is installed in the housing, then sound attenuation capability is achieved, but manufacturing costs increase and device complexity increases
Solution Approach 1:
The patent merges the housing wall with the membrane function by making the housing wall itself oscillatable and coupling it directly to the actuator. This eliminates the need for a separate membrane and cage structure, reducing device complexity while maintaining sound attenuation capability through the integrated wall-actuator system.
Solution Approach 2:
The housing wall is given multiple functions: it serves as both the structural enclosure and the oscillating membrane for sound attenuation. This multi-functionality eliminates the need for dedicated membrane components, simplifying the overall device structure while achieving the required acoustic performance.
2Reliability
If a complete electroacoustic transducer with cage, actuator and membrane is installed in the housing, then sound attenuation capability is achieved, but manufacturing costs increase
Solution Approach 1:
The patent merges the housing wall with the membrane function, eliminating the need for separate membrane and cage components. This reduction in part count directly lowers manufacturing costs while maintaining sound attenuation capability through the integrated wall-actuator system.
Solution Approach 2:
The patent extracts and eliminates unnecessary components (membrane and cage) from the traditional electroacoustic transducer design. By removing these redundant parts and using the housing wall directly as the oscillating element, manufacturing complexity and cost are reduced while preserving the essential sound attenuation function.
3Volume of moving object
If the actuator is exposed to exhaust gases, then compact design is achieved, but thermal damage risk increases and reliability decreases
Solution Approach 1:
The patent introduces a cage structure as an intermediary between the actuator and the exhaust gases. The cage allows the actuator to be positioned close to the housing wall for compact design while providing thermal protection, mediating between the need for compactness and the need to protect the actuator from thermal damage.
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 approach reduces production costs and enhances sound attenuation or amplification capabilities by using the existing housing structure, allowing for phase-shifted pressure pulsations to effectively cancel or amplify sound frequencies, while also simplifying the design and reducing thermal and contamination risks for the actuator.
Implementation Method 1
an actuator, which can excite the wall section to oscillate
Implementation Method 2
pressure pulsations can be introduced into the exhaust gas flow... as counter-vibrations to more or less cancel out the sound to be damped
Data Source
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
The present invention relates to a silencer (8) for an exhaust system (6) of an internal combustion engine (1), in particular of a motor vehicle, comprising a housing (14) having at least one exhaust gas inlet (18) and at least one exhaust gas outlet (19), a pipe arrangement (20) for exhaust gas routing arranged in the housing (14), comprising at least one pipe section (21) extending inside the housing (14), and at least one cavity (22) formed in the housing (14), which is additionally provided to the pipe arrangement (20) and is connected to it at least for the purpose of transmitting airborne sound.An inexpensive solution for active sound control can be achieved with at least one actuator (9) which is connected to a wall section (23) of the housing (14) which defines the outer boundary of the respective cavity (22) for the purpose of initiating vibrations, and with a control device (10) for active sound control which is connected to the at least one actuator (9) for its actuation.