Synthesized ABS Mirror Casing Eliminates Stick-Slip Squeak
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Solution Overview
Problem
Interior rearview mirrors in vehicles often produce noise or squeak when adjusted due to the stick-slip friction between plastic components, which is difficult to mitigate effectively without compromising manufacturing costs or aesthetics.
Innovation Solution
The use of a synthesized ABS material with an additional styrene copolymer, such as Hushlloy™, which alters the stick-slip property of the polymer to reduce friction and eliminate squeak noise, while maintaining the original attributes of the native ABS material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional plastic materials (native ABS) are used in mirror casing and bezel, then manufacturing cost and ease of manufacture are maintained, but noise or squeak is generated during mirror adjustment due to stick-slip friction
Solution Approach 1:
The patent modifies the chemical composition parameters of the ABS material by incorporating a specific copolymer (acrylonitrile-styrene-acetate copolymer) with controlled ratios of acrylonitrile (20-30%), styrene (65-80%), and acetate (10-30%). This chemical parameter change fundamentally alters the material's friction characteristics, reducing stick-slip noise while maintaining manufacturability through standard injection molding processes.
Solution Approach 2:
The patent creates a composite plastic material by combining native ABS with a specific copolymer formulation. The resulting composite material integrates the structural properties of ABS with the low-friction characteristics of the copolymer, achieving noise reduction during mirror adjustment without sacrificing manufacturing ease or structural integrity.
2Object-generated harmful factors
If additional materials or coatings are applied to reduce friction, then noise is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the noise-reduction function directly into the base plastic material by incorporating the copolymer during the injection molding process. This integration eliminates the need for separate friction-reducing coatings or additional components, as the low-friction properties are inherent to the molded parts themselves, thereby reducing device complexity.
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
Substantially reduces noise and squeak over the life cycle of the mirror assembly by permanently altering the stick-slip friction characteristics, providing a cost-effective and durable solution to the plastic squeak issue.
Implementation Method 1
the stick-slip property of the new molecular compound while maintaining all of the original attributes of the native ABS
Data Source
AI summary
An interior rearview mirror assembly for a vehicle includes a mirror reflective element and a mirror casing supporting the mirror reflective element. The mirror casing includes a synthesized ABS material having an additional styrene copolymer added to that of the native ABS in the polymerization process of the ABS material. The synthesized ABS may include a Hushlloy™ material. The mirror casing that is made of the synthesized ABS material may include a rear housing portion or a bezel.