Plastic Pipe Band-Layer Acoustic Impedance Design
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Solution Overview
Problem
Existing plastic pipe systems for wastewater conveyance generate disturbing noise due to airborne and structure-borne sound propagation, which is challenging to mitigate through density increases alone, as they complicate handling during installation.
Innovation Solution
The plastic pipe features extruded band-like layers on its inner and/or outer surfaces with varying densities, creating additional impedance jumps for sound reflection, and can include foamed structures to dissipate energy and reduce noise, while being designed for ease of installation and aesthetic appeal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the mass of the pipe is increased to achieve greater characteristic acoustic impedance and improve sound reflection, then the sound insulation effect is improved, but the handling during installation becomes more difficult
Solution Approach 1:
The patent applies local quality by creating discrete band-like layers with different densities at specific positions on the pipe surface, rather than uniformly increasing the entire pipe's mass. These localized high-density bands create impedance jumps for sound reflection while keeping the overall pipe mass low, thus maintaining ease of handling during installation.
Solution Approach 2:
The patent uses composite materials by combining base pipe material with extruded band-like layers of different densities (including high-density materials like barium sulfate or lead). This composite structure achieves the required acoustic impedance without uniformly increasing pipe mass, resolving the contradiction between sound insulation and ease of installation.
2Object-affected harmful factors
If filler consisting of barium sulphate is added to increase pipe density for sound reflection, then the characteristic acoustic impedance increases, but the mass of the pipe system increases making installation more difficult
Solution Approach 1:
High-density fillers like barium sulfate are concentrated in discrete band-like layers rather than being distributed throughout the entire pipe. This localized concentration creates the necessary acoustic impedance jumps at specific interfaces while minimizing the overall mass increase of the pipe system.
Solution Approach 2:
The patent changes the density parameter locally by introducing bands with different density values (e.g., 1.8-2.7 g/cm³ for barium sulfate-filled layers) against the base pipe material. This parameter variation at specific locations achieves sound reflection without requiring uniform high density throughout the entire pipe structure.
3Object-affected harmful factors
If extruded band-like layers are arranged on the pipe surface to create impedance jumps, then sound reflection is improved, but the device complexity increases
Solution Approach 1:
The pipe surface is segmented into distinct band-like layers with different densities, arranged in specific patterns (e.g., alternating high and low density bands). This segmentation creates multiple impedance jumps along the sound propagation path, improving sound reflection while maintaining a relatively simple overall structure that can be manufactured in one piece.
Solution Approach 2:
The extruded band-like layers serve multiple functions: they create acoustic impedance jumps for sound reflection, provide structural reinforcement, and can be integrated into the pipe manufacturing process. This multi-functionality reduces overall device complexity by combining several functions into a single structural feature.
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 effectively reduces noise propagation by creating multiple impedance jumps and dissipating energy, enhancing handling and visual appeal, thus minimizing audible disturbances in wastewater pipe systems.
Implementation Method 1
an attempt is made to impede the propagation of airborne or structure-borne noise by reflecting the propagating sound at individual discontinuities
Implementation Method 2
The sound reflection factor r is given by: The sound-insulating effect increases with a larger reflection factor r. In practice, this is achieved by as large an impedance jump as possible at the reflecting interface
Implementation Method 3
the foamed areas, both of the base pipe and of the extruded layers, can deform when force is applied by the waste water and the energy during deformation is thus converted into heat due to internal friction
Implementation Method 4
the energy during deformation is thus converted into heat due to internal friction
Data Source
Figure 1~2
AI summary
The pipe (1) has a base pipe (2), and an in-extruded strip-shaped layer (3a) arranged at an inner surface, where another in-extruded strip-shaped layer is arranged at an outer surface of the base pipe. The layers are arranged in a spaced manner such that the density of a material of the strip-shaped layers is different from the density of the base pipe material. The strip-shaped layers at the inner and/or outer surfaces have same strip width and are regularly arranged over the circumference of the plastic tube.