Exterior Trim Undulating Wall Rigidity
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Solution Overview
Problem
Conventional exterior trim for motor vehicles faces challenges in achieving structural rigidity without causing surface divots due to differential cooling rates during the molding process, which can lead to compromised strength and a compromised glossy, divot-free finish.
Innovation Solution
The exterior trim features a single undulating wall with sections defined by imaginary planes, injection molded with the body to provide structural rigidity while maintaining a glossy, divot-free surface, incorporating a recess or cut-out for HMI devices and a backing plate to support the circuit board and electrode film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the structural wall is molded thicker than the substrate thickness, then rigidity and strength are improved, but surface divots appear on the exterior surface due to differential cooling rates
Solution Approach 1:
The patent applies local quality by creating a multi-layer thickness distribution: the structural wall has a first thickness for rigidity, a second reduced thickness at the interface to match cooling rates, and a third thickness for the substrate. This localized variation in thickness allows different regions to serve different functions - the thicker structural wall provides strength while the thinner interface region prevents differential cooling shrinkage and surface divots.
2Manufacturing precision
If the structural wall is molded thinner than the substrate thickness, then surface divots are avoided, but rigidity and strength are compromised
Solution Approach 1:
The patent uses local quality by implementing a non-uniform thickness profile where the structural wall is thickest at its outer surface for maximum rigidity, transitions to a thinner intermediate layer for controlled cooling, and interfaces with the substrate at an appropriate thickness. This localized thickness variation ensures both structural integrity and surface quality.
Solution Approach 2:
The patent resolves the contradiction by adding a dimensional complexity to the wall thickness - instead of a single uniform thickness, it creates a multi-dimensional thickness profile with at least three distinct thickness regions. This dimensional approach allows the structure to simultaneously achieve rigidity (through the thicker outer wall) and surface quality (through the thinner interface region).
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 ensures structural rigidity and a smooth, glossy exterior surface by preventing deformation from differential cooling rates and repeated use, maintaining the exterior trim's integrity and aesthetic finish.
Implementation Method 1
as the molded material cools, the structural wall may cool at a rate that is different than that of the rest of the substrate
Implementation Method 2
When these cooling rates differ, the structural wall may shrink at a rate that is different than that of the rest of the substrate
Data Source
Figure 1~2
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AI summary
An exterior trim for a motor vehicle has a body (22) that forms a surface of the exterior trim. The body has an exterior surface (34) and an interior surface (32), and defines a recess or cut-out (36). The body has a single undulating wall (38) formed on the interior surface of the body substantially perpendicular to a plane defined by the body, and the single undulating wall at least partially surrounds the recess or cut-out. The exterior trim also includes a human-machine interface (HMI) device (21) disposed at least partially within the recess or cut-out of the body. The HMI device may be used to externally control certain features of the motor vehicle.