End-Stop Control Valve for Progressive Damper Damping
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Solution Overview
Problem
Vibration dampers with auxiliary pistons at both ends face issues with sudden jumps in damping force, leading to undesirable noise, vibration, and harshness (NVH) effects and changes in vehicle performance due to the step-function increase in damping force during end-stop events.
Innovation Solution
The vibration damper incorporates an end-stop control valve with a piston band and spring disc that gradually increase damping force by deflecting the valve disc stack-up and elastically deforming the spring disc, providing a progressive and smoother transition into end-of-stroke damping, reducing the sudden increase in force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If auxiliary pistons are used to increase damping force at end-stop positions, then the damping force is improved, but the sudden jump in damping force causes undesirable NVH effects and performance changes
Solution Approach 1:
The valve disc stack-up is designed to progressively deflect during compression, dynamically changing the flow area and damping force. Instead of a sudden step-function increase, the damping force builds gradually as the valve discs deflect under increasing pressure, transforming the static auxiliary piston action into a dynamic, progressive force application that reduces NVH effects
Solution Approach 2:
The invention changes the physical state and geometry of the valve disc stack-up under pressure. As compression force increases, the valve discs progressively deflect and change their effective flow area, transforming the damping characteristic from a sudden jump to a progressive curve. This parameter change approach allows the damping force to increase smoothly rather than abruptly
2Reliability
If auxiliary pistons engage suddenly to provide end-stop damping, then damping effectiveness is improved, but the transition into end-of-stroke damping becomes abrupt causing impact and performance changes
Solution Approach 1:
The valve disc stack-up begins to deflect and reduce flow area before the auxiliary piston fully engages. This preliminary action of progressive valve disc deflection prepares the system for end-stop damping by gradually building pressure and reducing flow, smoothing the transition into the high-damping state and preventing abrupt impact when the auxiliary piston engages
3Force
If a large increase in damping force is supplied by auxiliary piston engagement, then end-stop control is improved, but the rapid change in acceleration causes NVH effects
Solution Approach 1:
The progressive deflection of valve discs under increasing pressure creates a dynamic, continuous adjustment of flow area. This dynamic process spreads the force increase over time and displacement, reducing the rate of acceleration change. The system transitions from a static, sudden force application to a dynamic, progressive force build-up that minimizes NVH effects
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 reduces NVH effects and improves vehicle performance by providing a progressive increase in damping force, smoothing the transition into end-of-stroke damping and minimizing the sudden impact typically associated with standard auxiliary piston systems.
Implementation Method 1
the valve disc stack-up may be deflected by hydraulic pressure to reduce a flow area
Implementation Method 2
elastically deforming the spring disc, providing a progressive and smoother transition into end-of-stroke damping
Data Source
AI summary
An end-stop control valve can progressively add end-of-stroke damping resistance to complement the damping force provided by a main piston in a damper tube. The end-stop control valve may include a piston that selectively engages with a catch piston, both of which are longitudinally movable within the damper tube. To reduce bypass around the piston, a piston band wrapped at least partially around the piston may engage with a sidewall of the catch piston just prior to engagement of the catch piston and the piston, although at least some hydraulic fluid can flow through a pathway of the piston band. A spring disc that moves with the piston may also engage with the catch piston just prior to engagement between the catch piston and the piston. The spring disc may elastically deform to contribute end-of-stroke resistance leading up to engagement of the piston and the catch piston.