End-Stop Control Valve for Progressive Damper Damping
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Solution Overview
Problem
Existing vibration dampers experience sudden increases in damping force, leading to undesirable noise, vibration, and harshness (NVH) effects due to the step function increase in damping force when auxiliary pistons engage, particularly in extreme driving conditions.
Innovation Solution
The introduction of an end-stop control valve with an auxiliary piston that progressively increases damping force through varying preload from an initial to a maximum preload during the end-of-stroke damping event, using a valve piston insert and catch piston configuration that allows hydraulic fluid to flow freely or be trapped, depending on engagement, and a wave spring to separate components after the event.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If auxiliary pistons are engaged to increase damping force at end positions, then the damping force increases significantly, but the increase resembles a step function causing sudden jumps in damping force
Solution Approach 1:
The valve piston insert is made movable relative to the auxiliary piston, allowing the valve disc stack-up to dynamically adjust its position and the degree of fluid flow restriction. This creates a progressive, continuous increase in damping force rather than a sudden step function, as the valve piston insert moves in response to pressure differential forces during compression and rebound events.
Solution Approach 2:
The preload on the valve disc stack-up changes from an initial preload to a maximum preload during the end-of-stroke damping event. This parameter change is achieved through the relative movement between the auxiliary piston and valve piston insert, which progressively increases the clamping force on the valve disc stack-up, thereby smoothly increasing damping force.
2Force
If a large increase in damping force is supplied as the auxiliary piston is engaged, then the damping effect is improved, but large rapid change in acceleration and undesirable NVH effects occur
Solution Approach 1:
The dynamic valve piston insert allows the damping force to increase progressively rather than abruptly. As the auxiliary piston engages, the valve piston insert moves in response to pressure forces, gradually restricting fluid flow and increasing damping force. This dynamic adjustment prevents sudden jumps in acceleration and reduces NVH effects.
Solution Approach 2:
The valve piston insert acts as an intermediary between the auxiliary piston and the hydraulic fluid. It progressively restricts fluid flow through the valve disc stack-up, mediating the transition from low to high damping force. This intermediary mechanism smooths out the force transition and prevents direct, abrupt force application that would cause NVH effects.
3Stability of the object's composition
If the valve piston insert is secured to the piston rod and the auxiliary piston is movable relative to it, then progressive damping force increase is enabled, but device complexity increases
Solution Approach 1:
The valve piston insert is integrated with the valve disc stack-up and auxiliary piston assembly, combining multiple functions into a compact unit. The relative movement between components is achieved through their inherent mechanical connection, eliminating the need for separate actuation mechanisms and reducing overall system complexity despite the progressive damping function.
Solution Approach 2:
The valve piston insert automatically adjusts its position and the degree of fluid flow restriction in response to pressure differential forces generated during compression and rebound events. This self-adjusting mechanism eliminates the need for external control systems, sensors, or actuators, thereby maintaining relatively simple device architecture while achieving progressive damping force increase.
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 solution provides a smoother transition in damping force, reducing NVH effects and improving vehicle performance by gradually increasing damping force, thus minimizing sudden changes in acceleration.
Implementation Method 1
a wave spring to separate the auxiliary piston and the valve piston insert from one another after the end-of-stroke damping event
Implementation Method 2
allows hydraulic fluid to flow freely or be trapped, depending on engagement
Data Source
AI summary
A vibration damper includes an end-stop control valve that progressively adds end-of-stroke damping force to complement the damping force provided by a main piston. The end-stop control valve may include a valve piston assembly that has a valve piston insert, a piston that is disposed radially outside the valve piston insert, and a valve disc stack-up that is supported on a hub of the valve piston insert and a valve seat of the piston. The valve piston insert and the piston may be arranged so as to be longitudinally movable relative to one another. Consequently, the preload of the valve disc stack-up increases as the valve piston assembly contacts a catch piston and begins end-of-stroke damping. Transitioning from an initial preload to a maximum preload during the end-of-stroke damping event progressively increases damping resistance and thereby improves NVH characteristics.