Overstressed Windscreen Mounting for Flush A-Pillar Gaps
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Solution Overview
Problem
The challenge in designing motor vehicle body parts is to achieve precise and uniform gaps and flushness between the front windscreen and side doors, which is difficult due to manufacturing and assembly tolerances, leading to increased air-drag from airflow separation.
Innovation Solution
A motor vehicle design where the front windscreen is mounted in an overstressed condition by bending it slightly open and gluing it to the A-pillars, with A-pillar trims covering gaps and providing flushness between the windscreen and side doors, using a two-part A-pillar trim system with snap fit mechanisms and sealings to maintain airflow parallel to the side doors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mounting methods are used for the front windscreen, then assembly is simple, but gaps and surface discontinuities occur due to tolerance stack-up
Solution Approach 1:
The windscreen is pre-formed with a non-planar rear surface that includes compensation zones designed in advance to offset tolerance variations. This preliminary design action allows the windscreen to self-compensate for assembly tolerances without requiring complex real-time adjustments during mounting.
Solution Approach 2:
The rear surface geometry of the windscreen is changed from a conventional planar shape to a non-planar shape with specific curvature variations. This parameter change in surface geometry enables the windscreen to adapt to tolerance stack-up and maintain uniform gaps with adjacent body parts.
2Strength
If the windscreen is made rigid for structural strength, then strength is improved, but adaptability to tolerance variations decreases
Solution Approach 1:
The windscreen structure is designed with different local properties: the overall structure remains rigid for strength, while specific local zones (compensation zones) have modified surface geometry that provides adaptability. This local quality differentiation allows simultaneous achievement of strength and tolerance compensation.
Solution Approach 2:
The rear surface of the windscreen is conceptually segmented into different functional zones, including compensation zones with specific geometric characteristics. This segmentation allows different parts of the same component to serve different functions - structural integrity and tolerance adaptation.
3Loss of energy
If gaps between windscreen and side doors are reduced for aerodynamic efficiency, then air-drag is reduced, but manufacturing and assembly tolerances become more critical
Solution Approach 1:
The windscreen design incorporates self-compensating features where the non-planar rear surface automatically adjusts to tolerance variations during assembly. This self-service mechanism reduces gaps and improves aerodynamics without requiring external adjustment mechanisms or highly precise manufacturing.
Solution Approach 2:
The compensation zones on the windscreen act as an intermediary element between the rigid windscreen structure and the variable positioning of adjacent body parts. This intermediary geometry absorbs tolerance variations and maintains optimal gap dimensions for aerodynamic efficiency.
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 solution ensures a good fit of the front windscreen, reduces the impact of tolerances and geometrical imperfections, and maintains aerodynamic efficiency by maintaining airflow parallel to the side doors, thereby reducing aerodynamic drag.
Implementation Method 1
by bending the front windscreen open and placing it over and gluing it to the driver side A-pillar and co-driver side A-pillar
Data Source
Figure 1~2
Figure 3~5
Figure 6~9
AI summary
A motor vehicle cabin (2), comprising a front windscreen (8) having a central windscreen section (8A), curved corners (8B) and a straight windscreen driver and co-driver side portions (8C, 8D), and a driver and co-driver side door (9). The front windscreen (8) is glued in an overstressed mounted state to the driver and co-driver side A-pillar (5, 6) by using a front windscreen of which an outer width (w) at a specific height prior to mounting is smaller than a distance (d) between a most forward inner edges (5A, 6A) of the driver and co-driver side A-pillars (5, 6), by bending the front windscreen (8) open and placing it over and gluing it to the A-pillars (5, 6). The rear edge (12, 14) of the straight windscreen side portions (8C, 8D) are positioned on the outside of the A-pillars (5, 6) between the most forward inner edge and an outer edge thereof. A-pillar trims are arranged for covering side gaps and for providing flushness with the side doors.