Rear Hatch Mechanism with Variable Torque Compensation
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Solution Overview
Problem
Existing motor vehicle rear hatch mechanisms require high actuating forces to open and close due to varying torque and torsional moment, which is inconvenient and inefficient, especially as ambient temperature affects gas pressurized springs and torsion bar systems.
Innovation Solution
A mechanism using energy storage elements, such as torsion bar springs, with means to influence the torsional moment as a function of the opening position, ensuring moment equilibrium and reducing torque differences, allowing for low actuating forces and self-holding in various positions, using coupling elements and transmission systems like eccentric cams and levers to adapt torque characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gas pressurized springs are used to assist panel movement, then the panel can be opened and closed with less effort, but the support moment varies with ambient temperature making operation difficult in extreme temperatures
Solution Approach 1:
The patent changes the physical state of the energy storage element from gas pressurized (temperature-sensitive) to metal spring (temperature-insensitive), maintaining the supporting function while eliminating temperature dependency. The metal spring's elastic properties remain stable across temperature ranges, providing consistent support moment.
Solution Approach 2:
The patent replicates the function of gas pressurized springs using metal spring elements that provide equivalent mechanical support without the temperature sensitivity issue. The metal springs copy the load-bearing and energy-storing functions while avoiding the thermal expansion problems of gas-filled systems.
2Device complexity
If linear force/travel spring elements are used, then the mechanism is simple and robust, but the curved torque flow of the panel cannot be adequately compensated
Solution Approach 1:
The patent introduces dynamic adjustment capability through the cam mechanism that varies the spring lever arm length during panel movement. This transforms the static linear spring into a dynamically adjustable system that can adapt its mechanical advantage to match the curved torque requirements of the panel at different positions.
Solution Approach 2:
The cam mechanism acts as an intermediary between the linear spring and the panel, translating the linear spring force into a variable torque output. The cam profile mediates the force transmission, adjusting the effective lever arm to compensate for the panel's changing torque characteristics throughout its range of motion.
3Device complexity
If the spring lever arm length is fixed, then the mechanism is robust and simple, but the torque provided by the spring does not match the panel's torque requirements at different positions
Solution Approach 1:
The patent transforms the fixed lever arm into a variable lever arm system where the cam mechanism adjusts the effective distance from the spring force application point to the rotation axis. This dynamic adjustment allows the spring to provide optimal torque at each panel position, reducing actuating force requirements throughout the movement range.
4Ease of operation
If means for dynamically adjusting torsional moment are added, then torque matching improves, but the mechanism complexity increases
Solution Approach 1:
The cam mechanism serves multiple functions simultaneously: it adjusts the spring lever arm length, controls the timing of force application, and provides a mechanical linkage between the panel and spring system. This multi-functionality achieves sophisticated torque matching without adding excessive complexity, as one component performs several critical roles.
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 solution significantly reduces the manual force required to open or close the rear hatch, ensuring low actuating forces and self-holding in all positions, enabling convenient automatic operation and efficient energy use.
Implementation Method 1
at least one energy storage element and with means that are coupled to the same for influencing the torsional moment provided on the panel or door by the at least one energy storage element
Implementation Method 2
the respective torsional moment, which is applied by the torsion bar springs and which counteracts the torque of the rear hatch
Implementation Method 3
using coupling elements and transmission systems like eccentric cams and levers to adapt torque characteristics
Implementation Method 4
means for influencing the torsional moment as a function of the opening position
Implementation Method 5
can be brought from a closed position into an open position against the force of gravity
Data Source
AI summary
The invention relates to a motor vehicle having a panel or door, which can be brought from a closed position into an open position against the force of gravity using at least one energy storage element and means coupled therewith for influencing the torsional moment provided on the panel or door by the at least one energy storage element, wherein the panel or door is rotatably supported about an axis of rotation, and wherein the torsional moment can be influenced by the means for influencing depending on the opening position of the panel or door.