Silencer With Passive Flow Control And Acoustic Unseparation
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Solution Overview
Problem
Conventional silencers for internal combustion engine exhaust-gas systems face challenges in providing a consistent acoustic effect and low back pressure across varying engine speeds and loads, with active systems being costly and passive systems being complex and less effective.
Innovation Solution
A silencer design featuring a bypass pipe and a passive control element that directs gas flow and sound through an acoustically unseparated interior space, allowing for high acoustic absorption at low flows and low back pressure at high flows, achieved by maintaining equal sound-loaded volume with the control element open or closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a passive control element is used to direct gas flow, then the acoustical absorbing effect is improved at low mass flows, but the device complexity increases compared to simple silencers
Solution Approach 1:
The control element is passively actuated by the gas flow itself without requiring external control systems. The gas flow automatically opens or closes the control element based on its own characteristics, making the system self-regulating and eliminating the need for external actuators, control units, or additional components.
Solution Approach 2:
The silencer is divided into multiple flow paths: a first flow path for high mass flow conditions and a second flow path for low mass flow conditions. The control element selectively directs gas flow through different paths based on flow conditions, allowing optimized acoustic performance for each operating regime without requiring a completely different silencer design.
2Object-affected harmful factors
If active control systems are used with external control units and actuators, then the acoustical absorbing effect can be influenced, but the manufacturing costs increase significantly
Solution Approach 1:
The control element is passively actuated by the gas flow itself without requiring external control systems. The gas flow automatically opens or closes the control element based on its own characteristics, making the system self-regulating and eliminating the need for external actuators, control units, or additional components.
Solution Approach 2:
The passive control element uses simple, inexpensive components such as flaps or valves that can be manufactured at low cost. These components replace expensive active control systems while providing sufficient functionality for the application, significantly reducing manufacturing costs.
3Ease of manufacture
If passive control systems are configured to be simple, then the manufacturing costs are reduced, but the acoustical effect is limited and back pressure increases
Solution Approach 1:
The silencer is divided into multiple flow paths: a first flow path for high mass flow conditions and a second flow path for low mass flow conditions. The control element selectively directs gas flow through different paths based on flow conditions, allowing optimized acoustic performance for each operating regime without requiring a completely different silencer design.
Solution Approach 2:
The control element dynamically adjusts the flow distribution between different paths based on the instantaneous gas flow conditions. This dynamic adaptation allows the silencer to optimize its acoustic performance for varying operating conditions while maintaining a simple overall structure.
4Stress or pressure
If the interior space is acoustically unseparated, then the back pressure is reduced at high mass flows, but the acoustic absorption effect may be compromised
Solution Approach 1:
The silencer is divided into multiple flow paths: a first flow path for high mass flow conditions and a second flow path for low mass flow conditions. The control element selectively directs gas flow through different paths based on flow conditions, allowing optimized acoustic performance for each operating regime without requiring a completely different silencer design.
Solution Approach 2:
Different regions of the silencer are optimized for different functions: the first flow path is optimized for low back pressure at high mass flows, while the second flow path is optimized for high acoustic absorption at low mass flows. The control element directs flow to the appropriate region based on operating 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
The design achieves a high acoustic effect with low manufacturing costs and compact size, maintaining effective sound damping and low back pressure across different engine conditions.
Implementation Method 1
a passive operating control element (8) is arranged on and within the inlet pipe (4)
Implementation Method 2
the interior space (3), in which the outlet (5) of the inlet pipe (4), the outlet (7) of the bypass pipe (6) and the inlet (10) of the outlet pipe (9) are located, is acoustically unseparated
Data Source
AI summary
The invention relates to a silencer for an airborne sound conducting pipe system, including a housing enclosing an interior space, an inlet pipe having an outlet within the interior space, a bypass pipe branching off from inlet pipe within the housing and having an outlet, a control element actuated by the gas flow and arranged downstream of bypass pipe on or in the inlet pipe, and at least one outlet pipe having an inlet within the interior space. Furthermore, the interior space is acoustically unseparated in such a manner that the volume of the interior space loaded with the airborne sound is equal with opened and with closed control element.