Tolerance Compensating Hinge Attachment for Lift Gate
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Solution Overview
Problem
The assembly of SUV lift gates is hindered by inconsistencies in hinge and hinge mounting structures, leading to misalignment and fit and finish issues due to variations in mounting face, compression limiters, and structural bracket placement, necessitating time-consuming custom fitting and adjustments.
Innovation Solution
A method involving a first fixture to hold hinges in predetermined vehicle locations and a second fixture to position the lift gate, using self-adjusting moveable fasteners to ensure proper alignment and gap tolerance between the lift gate and vehicle, with tolerance compensating fasteners and part nesting to compensate for dimensional variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional rivet nut fasteners are used to attach hinges to the lift gate, then the attachment process is simple, but misalignment and fit and finish issues occur due to mounting face variation and structural bracket location variation
Solution Approach 1:
The hinge is pre-assembled with a positioning bracket that includes locating features matching the vehicle body mounting holes. This preliminary assembly ensures correct positioning before attachment to the lift gate, eliminating misalignment issues that would otherwise require time-consuming custom fitting and adjustments
Solution Approach 2:
A positioning bracket serves as an intermediary component between the hinge and the lift gate mounting structure. This bracket includes locating features that interface with the vehicle body mounting holes, acting as a mediator to transfer precise positioning from the vehicle body to the hinge assembly, thereby compensating for variations in the lift gate mounting face
2Manufacturing precision
If custom fitting and adjustments are performed to achieve proper fit and finish, then alignment precision improves, but assembly time increases significantly
Solution Approach 1:
The positioning bracket is pre-configured with locating features that match the vehicle body mounting holes. This preliminary preparation eliminates the need for time-consuming custom fitting and adjustments during final assembly, as the hinge is already positioned correctly before attachment to the lift gate
Solution Approach 2:
The positioning bracket with its locating features enables the hinge assembly to self-position correctly on the vehicle body. The locating features automatically align with the mounting holes, allowing the assembly to be self-aligning without requiring manual adjustment or custom fitting, thereby reducing assembly time while maintaining precision
3Device complexity
If fixed attachment faces are used on the lift gate, then the attachment structure is simple, but assembly difficulties arise due to compression limiters not being fully seated and inner panel distortion
Solution Approach 1:
The positioning bracket acts as an intermediary that interfaces with the vehicle body mounting holes rather than relying solely on the lift gate mounting face. This mediator approach transfers the mounting reliability requirement from the problematic lift gate face to the more stable vehicle body structure, compensating for issues like compression limiters not being fully seated or inner panel distortion
Data Source
AI summary
A lift gate door having hinges installed for predetermined positioning into a vehicle. And a method of attaching a lift gate door to a vehicle while maintain proper tolerances. A first fixture holds a set of hinges in predetermined locations which correspond to assembly locations on a vehicle body. Hinges are temporarily attached to the fixture corresponding to the proper vehicle location. A second fixture holds the lift gate in a position which is a final installation position for attaching the lift gate to a vehicle. Self-adjusting moveable fastening nuts are provided in a set of holes in a hinge plate fastening area of the lift gate. The first fixture is moved into aligned orientation with the second feature and the hinges are attached to the lift gate with the fastener. The hinge is aligned in the proper installation orientation for maintaining the lift gate to vehicle gap in proper tolerances when the lift gate door with hinges is installed on the final vehicle.