Flap for a motor vehicle shut-off device and method for manufacturing such a flap
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Solution Overview
Problem
The existing motor vehicle shut-off device flaps, particularly those used in Active Grill Shutter systems, face significant bending and torsional stresses due to wind and actuator forces, leading to deformations that impair their ability to effectively shut off air inlets and disrupt the aerodynamics and fuel efficiency of vehicles.
Innovation Solution
The flaps are made from a fiber-reinforced composite material, specifically continuous fiber-reinforced composite materials, with a hollow closed contour cross-section and strategically placed reinforcing fibers extending in various directions to enhance stiffness and resistance to operational stresses, combined with plastic end pieces for secure mounting and actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flaps are made from plastic material (injection molded), then manufacturing is simple and cost-effective, but the flaps deform under bending and torsional stresses from wind and actuator forces
Solution Approach 1:
The flap is constructed as a composite structure consisting of a plastic body (providing ease of manufacture) reinforced with fiber-reinforced composite material strips (providing resistance to bending and torsional stresses). The fiber-reinforced strips are arranged in specific orientations to counteract the stress directions, while the plastic body maintains manufacturing simplicity through injection molding processes.
2Strength
If flaps are made from fiber-reinforced composite material, then resistance to operational stresses is significantly increased, but manufacturing complexity and cost increase
Solution Approach 1:
The flap is divided into distinct segments: a plastic body and separate fiber-reinforced composite material strips. This segmentation allows each component to be manufactured using optimized processes (injection molding for the plastic body, fiber placement for the strips) and then assembled together, reducing overall manufacturing complexity while maintaining high stress resistance.
Solution Approach 2:
The invention merges two different material systems (plastic and fiber-reinforced composite) into a unified flap structure. The plastic body provides the base structure and mounting features, while the fiber-reinforced strips provide enhanced mechanical properties. This combination allows the flap to achieve high strength without requiring the entire structure to be manufactured as a complex composite part.
3Loss of energy
If flaps are made hollow with closed contour cross-section, then aerodynamic efficiency is improved and material usage is reduced, but structural stiffness may be compromised
Solution Approach 1:
The hollow closed-contour structure is constructed using fiber-reinforced composite material strips embedded in the plastic body. The fibers are oriented to provide stiffness in critical directions while maintaining the hollow cross-section for aerodynamic efficiency. This composite construction allows the thin-walled hollow structure to achieve the required structural stability without compromising aerodynamic performance.
Data Source
AI summary
The invention relates to a shut-off flap (26) for a motor vehicle shut-off device, notably for a device for shutting off an air inlet in the front face of a motor vehicle, comprising a flap body (28), the flap body (28) being at least partially made of a fibre reinforced composite material, notably one that uses continuous reinforcing fibres (42, 44). The invention also relates to a motor vehicle shut-off device comprising such a flap and to methods of manufacturing this flap and this shut-off device for a motor vehicle.