Tailgate Lift Assist Pivot Bushing for Debris-Resistant Joints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vehicle tailgates, particularly for pick-up trucks, face issues with debris ingress, wear, and instability due to exposure to harsh environments and vibrational loads, leading to degraded performance and increased maintenance needs.
Innovation Solution
A removable tailgate system with an overmolded unitary bushing and annular ribs that seals the joint from debris, combined with a gas strut for lift assistance, reducing environmental and vibrational effects while maintaining a robust structure with fewer parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional separate bushings and fasteners are used in tailgate hinging joints, then assembly and disassembly are straightforward, but the joints are exposed to debris and weather leading to wear and instability
Solution Approach 1:
The patent combines multiple separate components (bushings, fasteners, sealing elements) into a single integrated overmolded unitary bushing assembly. This merging eliminates gaps and interfaces where debris could enter, while the integrated design maintains all necessary functions of rotation, positioning, and sealing in one robust component.
Solution Approach 2:
The overmolded unitary bushing employs composite construction with a rigid core structure for mechanical strength and rotational function, combined with elastomeric or polymer overmolding for sealing and damping. This composite approach provides both structural integrity against vibrational loads and effective sealing against debris and moisture ingress.
2Ease of manufacture
If multiple separate components are used in the tailgate mechanism, then individual parts can be manufactured easily, but the overall system complexity increases and wear points multiply
Solution Approach 1:
The patent integrates multiple functions into the overmolded unitary bushing: the rigid core provides structural support and rotational capability, while the elastomeric overmold provides sealing, damping, and wear resistance. This consolidation reduces the total part count while maintaining manufacturability through overmolding processes that combine different materials in one operation.
3Ease of operation
If loose fittings are used to permit tailgate removal, then installation and removal are easy, but the fittings become unstable under vibrational and inertial loads
Solution Approach 1:
The overmolded unitary bushing incorporates flexible elastomeric elements that provide dynamic adaptation to loads and misalignments. The elastomeric material deforms elastically under vibrational and inertial loads, maintaining stable engagement while allowing for thermal expansion, manufacturing tolerances, and operational flexure, thus preserving both stability and ease of removal.
4Device complexity
If exposed hinging joints are used, then the mechanism is simple and accessible, but friction and wear increase due to contact with debris and weather
Solution Approach 1:
The overmolded unitary bushing uses a composite structure where the elastomeric overmold creates a protective envelope around the rigid core and internal mechanisms. This composite design maintains mechanical simplicity while the elastomeric layer provides continuous sealing against debris and moisture, eliminating friction and wear issues associated with exposed joints.
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 system effectively seals against debris and moisture, reduces wear and instability, and provides smooth operation with reduced maintenance, enhancing the durability and functionality of the tailgate mechanism.
Implementation Method 1
an energy storage device located within the vehicle body and adapted to be pivotally anchored at a first end to the vehicle body... provides smooth operation with reduced maintenance
Implementation Method 2
providing annular ribs at opposite ends of the overmolded bushing, which ribs are compressed when the mechanism is assembled, provides an excellent sealing fit with the rotating actuation shaft assembly, preventing ingress of debris and foreign matter into the joint
Implementation Method 3
a pivot bearing arrangement to facilitate a robust rotary joint about the tailgate pivot axis, wherein the pivot bearing arrangement comprises a unitary component overmolded to a pivot sleeve to act as a bushing between the actuation shaft and the pivot sleeve
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A vehicle tailgate lift assist system comprises a vehicle tailgate adapted to open and close by rotating about a tailgate pivot axis in relation to a vehicle body, coupling means to releasably connect the vehicle tailgate and the vehicle body, an energy storage device located within the vehicle body and adapted to be pivotally anchored to the vehicle body at one end, a crank arm pivotally attached to the energy storage device at a second end of the energy storage device and rigidly attached to an actuation shaft that is coaxially aligned with the tailgate pivot axis, and a pivot bracket assembly comprising a mounting bracket fixed to the vehicle body and holding a pivot bearing arrangement to facilitate a robust rotary joint about the tailgate pivot axis. The pivot bearing arrangement comprises a unitary component overmolded to a pivot sleeve to act as a bushing between the actuation shaft and the pivot sleeve, such that relative rotary motion of the tailgate and the vehicle body results in linear movement of the energy storage device and maximum energy storage at the tailgate fully open position.