Tailgate Gas Spring Valve Switching for Pressure Overload Protection
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Solution Overview
Problem
Existing drive arrangements for motor vehicle flaps, such as tailgates, can suffer damage to gas pressure elements due to high piston speeds and pressure gradients, leading to potential failure when the drive force or holding force fails.
Innovation Solution
A gas pressure element with a switchable valve arrangement that adjusts the cross-section of the overflow channel based on pressure gradients to prevent damage, featuring states that optimize pressure equalization and damping to manage high forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gas pressure element is used to compensate for tailgate weight and provide holding force, then the tailgate can be kept in equilibrium or urged in the opening direction, but high piston speeds and pressure gradients can cause damage to the gas pressure element
Solution Approach 1:
The valve arrangement dynamically adjusts the overflow channel cross-section based on real-time pressure gradient conditions. The valve body can assume different switching positions (open, constricted, closed) depending on the pressure gradient magnitude, allowing the system to adapt its damping characteristics to match operational demands while preventing damage from excessive pressure gradients
Solution Approach 2:
The patent changes the physical parameter of the overflow channel cross-section area from fixed to variable. By adjusting the valve body position, the effective cross-section area of the overflow channel is modified, which directly controls the maximum flow rate and pressure gradient characteristics of the gas pressure element
2Object-affected harmful factors
If the valve arrangement switches to closed state to block further flap adjustment, then damage is prevented, but the system loses adaptability to different operating conditions
Solution Approach 1:
The valve arrangement operates dynamically across three distinct states (open, constricted, closed) based on pressure gradient thresholds. This dynamic multi-state operation provides adaptability to different operating conditions while maintaining protection capabilities, unlike a simple binary open/closed valve system
Solution Approach 2:
The valve arrangement provides beforehand cushioning by progressively restricting flow before critical damage conditions occur. The constricted state acts as an intermediate protective state that reduces pressure gradients to safe levels while maintaining operational flexibility, preventing the need for complete closure in many scenarios
3Stress or pressure
If the overflow channel has a large cross-section for pressure equalization, then pressure gradients are reduced, but piston speed control and damping are compromised
Solution Approach 1:
The overflow channel cross-section is made dynamic rather than static. The valve body position determines the effective cross-section area, allowing the system to provide large cross-section for pressure equalization when needed (open state) and restrict flow for speed control when needed (constricted or closed states)
Solution Approach 2:
The patent changes the overflow channel cross-section parameter from fixed to variable through valve body positioning. This allows the system to optimize the cross-section area for different operational requirements: large area for pressure equalization during normal operation, small area for speed control and damping during high-speed or overload conditions
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 effectively protects the gas pressure element from damage by automatically adjusting to high piston speeds and forces, ensuring reliable operation and preventing flap closure issues.
Implementation Method 1
The gas pressure element (4) has an outwardly sealed cylinder (6) and a piston (8) running in the cylinder interior (7) along a cylinder axis (A), dividing the cylinder interior (7) into two sub-chambers (7a, 7b). The cylinder (6) is filled with a fluid, in particular a fluid under pressure.
Implementation Method 2
the piston (8) has an overflow channel arrangement (9), through which a compensating flow is created between the two sub-chambers (7a, 7b) upon piston movement to compensate for a pressure gradient between the two sub-chambers (7a, 7b)
Implementation Method 3
a switchable valve arrangement (10) is assigned to the piston (8), which can be brought into different flow states depending on the pressure gradient between the two sub-chambers (7a, 7b), which differ in the size of the cross-section of the overflow channel arrangement (9)
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3c
AI summary
The invention relates to a drive arrangement for a flap (2) of a motor vehicle having at least one gas pressure element (4), in particular having a gas spring, wherein the gas pressure element (4) has an outwardly sealed cylinder (6) and a piston (8) which runs in the cylinder interior (7) along the cylinder axis (A) and which subdivides the cylinder interior (7) into two sub-chambers (7a, 7b), wherein the gas pressure element (4) has a first drive connection (4a), which is connected to the cylinder (6), and a second drive connection (4b), which is connected to the piston (8), wherein the cylinder (6) is filled with a fluid, in particular a pressurized fluid, wherein the piston (8) has an overflow channel arrangement (9) through which, in response to a piston movement, a balancing flow between the two sub-chambers (7a, 7b) occurs to balance a pressure drop between the two sub-chambers (7a, 7b), and wherein the piston (8) is assigned a switchable valve arrangement (10) which, depending on the pressure drop between the two sub-chambers (7a, 7b), can be brought into different through-flow states which differ in the size of the cross section of the overflow channel arrangement (9). It is proposed that, upon exceeding a predetermined upper limit value for the pressure drop, the valve arrangement (10) automatically switches into an overload state in which it increases the cross section of the overflow channel arrangement (9).