Plastic Speaker Shell With Overmolded Metal Inserts
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Solution Overview
Problem
Acoustic enclosures with large loudspeakers, such as woofers, often experience mechanical instability and hull vibrations due to pressure fluctuations, and existing solutions for fixing loudspeakers on the internal side of the shell are difficult or impossible for certain shapes, leading to instability issues.
Innovation Solution
The design incorporates a metal frame nested along the longitudinal axis of a plastic shell with overmolded metal inserts that provide structural support and secure the loudspeakers, using a combination of a metal frame and plastic shell to reduce vibrations and mechanical instability, with the metal inserts being made from stainless steel and the plastic shell having an inner layer of polycarbonate reinforced with glass fibers and an outer layer of acrylonitrile butadiene styrene (ABS).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large bass speaker is mounted across the opening of the plastic shell, then the acoustic performance is improved, but mechanical instability and vibrations of the shell occur due to pressure fluctuations
Solution Approach 1:
The patent applies composite materials by combining a plastic shell with metal reinforcement elements (metal frame or metal insert). The plastic shell provides acoustic insulation and aesthetic properties, while the metal elements provide mechanical strength and stability to resist pressure fluctuations from the bass speaker. This composite structure resolves the contradiction between achieving good acoustic performance with a plastic shell and maintaining mechanical stability under speaker-induced pressure variations.
2Stability of the object's composition
If the speaker is mounted on the inside of the shell around the edge of the opening, then mechanical stability is improved, but the mounting becomes difficult or impossible for certain casing shapes
Solution Approach 1:
The patent introduces an intermediary element (metal frame or metal insert) that mediates between the plastic shell and the speaker mounting requirements. This intermediary provides a suitable mounting surface and structural support for the speaker, enabling stable mounting even on complex shell shapes where direct mounting would be difficult or impossible. The intermediary element adapts to various shell geometries while providing the necessary mechanical stability.
3Stability of the object's composition
If a metal frame with overmolded metal inserts is used to reinforce the plastic shell, then vibrations and mechanical instability are reduced, but the device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated structure. The metal frame or insert serves multiple purposes simultaneously: it reinforces the plastic shell against pressure fluctuations, provides mounting support for the speaker, and acts as a vibration-damping element. This merging of functions reduces the need for separate reinforcement components, thereby managing device complexity while achieving vibration reduction and mechanical stability.
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 configuration effectively reduces mechanical instability and vibrations, providing a stable acoustic enclosure that minimizes hull vibrations and enhances the structural integrity of the loudspeaker system.
Implementation Method 1
a plastic shell defining at least one opening... likely to lead to mechanical instability or vibrations of the shell, for example caused by pressure fluctuations inside the acoustic enclosure
Implementation Method 2
The acoustic enclosure includes two metal inserts (17A, 17B) overmolded by the shell (7)... effectively reduces mechanical instability and vibrations, providing a stable acoustic enclosure that minimizes hull vibrations
Data Source
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AI summary
An acoustic enclosure comprising: - a plastic shell (7) defining at least one opening (9A), and - at least one loudspeaker defining a transverse axis (T) of the acoustic enclosure and extending across the opening. The acoustic enclosure includes at least one metal insert (17A) overmolded by the shell (7).