Liftgate Inner Panel Stiffener Nesting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional liftgates are heavy, prone to vibration, and have manufacturing inefficiencies due to the size and complexity of die-casting magnesium panels, which limits weight reduction and increases production costs.
Innovation Solution
A liftgate design featuring a die-cast inner panel with a reduced rear window envelope, integrally formed stiffeners, and separately mounted outer panels, allowing for thinner wall thicknesses and reduced vibration through adhesive fixation and optimized die-casting processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the rear window opening is decreased in size to reduce liftgate weight, then the area available for introducing molten magnesium through sprue and gates is reduced, but this limits the minimum nominal thickness of the inner panel and thus the minimum weight achievable
Solution Approach 1:
The patent introduces a third dimension by creating a header cavity between the header member and outer header panel, allowing the stiffener to protrude into this new spatial dimension. This dimensional change enables the stiffener to provide structural support without increasing the panel thickness, thereby maintaining weight reduction while achieving vibration stabilization.
Solution Approach 2:
The stiffener is nested within the header cavity, with the stiffener protruding from the header member into the header cavity and being fixed to the outer header panel. This nesting arrangement allows multiple functional elements (stiffener, header member, outer header panel) to occupy overlapping spatial volumes, maximizing structural efficiency within constrained dimensions.
2Ease of manufacture
If separate taillight cans are used to achieve sufficient depth, then the manufacturing complexity and assembly time increase, but integrating taillight cans into the inner panel requires severe draft angles that are too severe for stamping
Solution Approach 1:
The taillight cans are merged with the inner panel by die-casting them as an integrated feature of the inner panel. This combining of previously separate components (taillight cans and inner panel) into a single die-cast piece eliminates the need for separate stamping operations and assembly steps, thereby improving ease of manufacture while reducing device complexity.
3Stability of the object's composition
If draft angles and geometry are used to stabilize the liftgate, then additional separate parts are required to be mounted to the liftgate, but these additional parts increase assembly time and cost
Solution Approach 1:
The stabilizing function is merged with the inner panel by die-casting stiffeners as an integrated feature of the inner panel. This eliminates the need for separate stabilizing parts and their associated assembly operations, thereby maintaining liftgate stability while improving productivity by reducing assembly time and cost.
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
The design achieves a lighter liftgate with reduced vibrations and manufacturing complexity, enhancing fuel economy and reducing production time and costs by enabling thinner magnesium panels and integrated features like taillight cans and speaker housings.
Implementation Method 1
The stiffener protrudes from the header member into the header cavity and is fixed to the outer header panel
Implementation Method 2
A liftgate design featuring a die-cast inner panel with a reduced rear window envelope
Data Source
AI summary
A vehicle liftgate includes a die-cast inner panel and an outer header panel. The inner panel includes a header member, a pair of supports, a lower section, and at least one stiffener. The header member has a top edge and a bottom edge. The supports couple the header to the lower section. The supports and the bottom edge of the header member partially define a window aperture. The stiffener is coupled to the header member between the top and bottom edges and between opposite ends of the header member. The outer header panel is mounted to the header member to define a header cavity between the header member and the outer header panel. The stiffener protrudes from the header member into the header cavity and is fixed to the outer header panel.