Hydraulic Damper Velocity-Threshold Damping Control
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Solution Overview
Problem
Current hydraulic suspension dampers inadequately dissipate mechanical energy during extreme loading conditions, leading to increased suspension deflections, noise, and reduced safety and durability, especially when the wheel bounce velocity exceeds a predefined threshold.
Innovation Solution
The method generates additional damping forces as long as the piston velocity exceeds a deactivation threshold, which is lower than the activation threshold, and returns to comfort-relevant damping characteristics when the velocity drops below this threshold, using a specially designed valve system to enhance energy dissipation without interfering with normal operating ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If additional damping forces are generated when piston velocity exceeds activation threshold, then energy dissipation during impact loading is improved, but peak damping forces increase leading to noise and jerk excitation
Solution Approach 1:
The invention changes the parameter of damping force by introducing a time-dependent decay factor that reduces the damping force magnitude over time while maintaining the velocity threshold activation mechanism. This allows energy dissipation to be improved initially while the decay reduces peak forces and associated noise/jerk excitation in subsequent cycles.
Solution Approach 2:
The invention implements periodic action through the decay mechanism that operates in cycles: when velocity exceeds the activation threshold, additional damping force is generated; when velocity falls below the threshold, the damping force decays back to baseline. This periodic activation and decay pattern improves energy dissipation during impact while allowing the system to return to comfort-mode operation, reducing continuous noise and jerk excitation.
2Reliability
If damping force is increased for safety relevant region, then suspension control during impact loading is improved, but suspension deflections increase leading to closure or bumper engagement
Solution Approach 1:
The invention changes the damping force parameter dynamically by applying a decay factor that reduces force magnitude over time. During impact loading, the decayed damping force provides sufficient suspension control to prevent closure or bumper engagement, while the reduced force magnitude allows for smaller suspension deflections compared to conventional high-force dampers.
3Loss of energy
If damping force expands and contracts according to velocity threshold, then energy dissipation is improved, but force decay is abrupt causing noise and jerk excitation
Solution Approach 1:
The invention transforms the abrupt force expansion and contraction into a smoother decay pattern by introducing a time-dependent decay factor. Instead of sudden force changes at velocity thresholds, the damping force decays gradually over time according to a decay function, maintaining energy dissipation effectiveness while eliminating abrupt transitions that cause noise and jerk excitation.
4Object-generated harmful factors
If maximum damping force is reduced for comfort, then ride comfort is improved, but energy dissipation capability during impact loading is insufficient
Solution Approach 1:
The invention makes the damping force dynamic by introducing a time-varying decay factor that adapts the force magnitude based on operating conditions. During normal comfort-relevant operation, the damping force remains at comfortable levels. During impact loading events, the decay mechanism allows the damping force to provide enhanced energy dissipation capability while still returning to comfort levels when velocity decreases, thus resolving the contradiction between comfort and impact performance.
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
This approach increases energy dissipation during impact loadings, improving car comfort and safety while reducing peak forces and noise, allowing for smoother force decay and extended effective stroke to decelerate unsprung masses effectively.
Implementation Method 1
Damper comprises a set of rebound and compression valve assemblies which control the flow of working liquid between compression, extension and reservoir chambers of the damper
Implementation Method 2
A typical telescopic hydraulic suspension damper comprises a tube filled with working liquid, inside of which a slidable piston assembly is placed
Data Source
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AI summary
The invention relates to a novel dissipation method of impact loadings, met in particular in a hydraulic suspension damper of a motor vehicle during extreme events, where the damping force (F) is adjusted in a function of the piston velocity (V) according to some predefined comfort and safety relevant characteristics. To achieve additional dissipation of mechanical energy, the method involves generation of additional damping forces, which are generated as long as the piston velocity magnitude is above a predefined deactivation threshold (VDT); which is significantly lower than the additional damping forces activation threshold (VAT), and when the piston velocity decreases below the deactivation threshold the damping force returns to the comfort relevant characteristic below the activation threshold. By using velocity sensitive system with different thresholds, the mechanical energy is dissipated without high peak forces generation and independently on the suspension position. The invention beneficially affects a car performance concerning comfort, safety, noise, and durability. Measurement results of damping force, generated according to the inventive method using a specially designed valve system in a hydraulic damper, are also presented.