Switchable Muffler Helmholtz Resonator Engine Speed Adaptation
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Solution Overview
Problem
Conventional mufflers for internal combustion engine exhaust systems struggle to adapt to changing engine speeds, leading to inadequate noise muffling and increased fuel consumption due to fixed resonance frequencies and flow resistance.
Innovation Solution
A switchable muffler design featuring a Helmholtz resonator with a switchable second outlet pipe that modifies its resonance frequencies and flow resistance by connecting or disconnecting, allowing adjustment to different engine operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional mufflers with fixed resonance frequencies are used, then noise muffling is achieved at specific engine speeds, but noise reduction becomes inadequate when engine speed changes
Solution Approach 1:
The patent implements a switchable second outlet pipe that can be connected or disconnected based on engine operating conditions. This dynamic configuration allows the Helmholtz resonator to adjust its resonance frequency, enabling effective noise muffling across varying engine speeds rather than being fixed at a single frequency.
Solution Approach 2:
The patent changes the physical parameters of the Helmholtz resonator by modifying the effective volume and neck dimensions through the switchable outlet pipe. By connecting or disconnecting the second outlet pipe, the resonator's volume and acoustic impedance are adjusted, thereby changing its resonance frequency to match different engine operating conditions.
2Object-affected harmful factors
If mufflers are designed for maximum exhaust gas stream at high speeds, then noise muffling is improved, but flow resistance increases significantly at medium speeds
Solution Approach 1:
The switchable second outlet pipe enables the muffler to dynamically adjust its flow resistance characteristics. At high engine speeds, the pipe remains connected to maintain low flow resistance and reduce fuel consumption. At medium speeds, the pipe can be disconnected to increase flow resistance and enhance noise muffling effectiveness, optimizing the balance between noise reduction and energy efficiency.
Solution Approach 2:
The patent changes the flow resistance parameter of the exhaust system by switching the second outlet pipe configuration. This allows the system to optimize the trade-off between noise muffling and flow resistance at different operating points, reducing energy loss at high speeds while maintaining noise control at medium speeds.
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 enhances noise muffling and reduces fuel consumption by dynamically changing the muffling characteristics and flow resistance in response to varying engine speeds, improving noise reduction and engine efficiency.
Implementation Method 1
A Helmholtz resonator consists of a body enclosing an air volume, the body comprising a resonator neck having an opening connecting the air volume with the surroundings. The elasticity of the air volume inside the body combines with the inertial mass of the air present in the resonator neck to form a mechanical mass-spring system.
Implementation Method 2
The Helmholtz resonator being switchable between at least two different resonance frequencies (natural frequencies). The natural frequency depends inter alia on the size of the air volume enclosed, the cross-sectional area of the opening in the resonator neck, the length of the resonator neck.
Implementation Method 3
Respective mufflers may, for instance, work according to the absorption and/or reflection principle.
Implementation Method 4
Respective mufflers may, for instance, work according to the absorption and/or reflection principle.
Data Source
AI summary
A muffler (1) for an exhaust system of a vehicle driven by an internal combustion engine, includes a gas-tight housing (2), a partition wall (31) inside the housing, an inlet pipe (51), a first outlet pipe (61), a switchable second outlet pipe (7) and a resonator pipe (8). The a partition wall (31) divides the housing's interior into a first volume (41) and a second separate volume (42). The inlet pipe and the first outlet pipe (61) and the second outlet pipe and the resonator pipe are in fluid communication with the first volume. The resonator pipe provides fluid communication between the first volume and the second volume. The second outlet pipe passes through the second volume. The second outlet pipe is surrounded, in a circumferential direction, by the resonator pipe in a section in which the second outlet pipe penetrates the partition wall.