Two-Stage Shock Absorber Valves for Hydro Lock Prevention

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Solution Overview

Problem

Conventional shock absorbers face issues with overshoot and oscillation due to hydro locking and premature valve closure, especially in sudden terrain changes, leading to a harsher riding experience and increased manufacturing complexity.

Innovation Solution

The development of two-stage hydraulic boost valves and pressure-balanced poppet valves that control fluid flow by using shims, pilot chambers, and spring mechanisms to prevent hydro locking and oscillation, allowing for smoother operation and reduced manufacturing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional damping components are used, then the damping rate is constant throughout the stroke, but the ability to adapt to varying terrain conditions is poor

Engineering Contradiction:

Improveadaptability to terrain conditionsVSAvoiddamping component complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The valve system transitions from a static constant damping rate to a dynamic variable damping rate by using a main damping piston with frequency-dependent valve elements (first and second valves) that automatically adjust opening degrees based on oscillation frequency and stroke position, enabling adaptation to varying terrain conditions without requiring complex external control systems

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The damping component achieves adaptive damping through self-regulating mechanisms where the main damping piston and associated valves automatically adjust their opening degrees in response to changing oscillation frequencies and stroke positions, eliminating the need for external sensors or control systems while maintaining optimal damping performance

Inventive Principle:

Principle #25Self-service

2Reliability

If conventional valves are used in sudden terrain changes, then the valve may close prematurely due to hydro locking, but this leads to overshoot and oscillation

Engineering Contradiction:

Improvevalve operation reliabilityVSAvoidovershoot and oscillation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The frequency-dependent valve design anticipates rapid terrain changes by maintaining adequate opening degrees during high-frequency oscillations, preventing hydro locking before it occurs and ensuring continuous fluid flow path is available to dampen sudden impacts without causing overshoot

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The valve opening degree dynamically changes based on oscillation frequency parameters, with the first and second valves adjusting their effective opening areas in response to frequency-dependent pressure differentials across the main damping piston, preventing hydro locking and associated harmful effects

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the damping rate is varied to improve ride comfort, then the manufacturing complexity increases

Engineering Contradiction:

Improveride comfortVSAvoidmanufacturing complexity

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The damping system is segmented into distinct functional zones within the main damping piston, with separate first and second valves positioned at different locations to handle different stroke phases and frequency ranges, allowing varied damping rates to be achieved through geometric design rather than complex assembly procedures

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The frequency-dependent damping variation is achieved through hydraulic pressure differential mechanisms acting on the first and second valves, where fluid pressure changes during oscillation automatically modulate valve opening degrees without requiring mechanical linkages, electronic controls, or complex manufacturing processes

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 prevents hydro locking and oscillation, providing a smoother ride by allowing fluid to flow without volume change and filtering high-frequency vibrations, while simplifying the design and reducing manufacturing costs.

Implementation Method 1

spring mechanisms to prevent hydro locking and oscillation

Methodology Applied

Scientific EffectSpring mechanism: Spring

Implementation Method 2

two-stage hydraulic boost valves that control fluid flow

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 3

allowing fluid to flow without volume change

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 4

pressure-balanced poppet valves that control fluid flow

Methodology Applied

Scientific EffectPressure balance:

Data Source

PatentUS20220412430A1Frequency dependent 2-stage valves for shock absorbers

Publication Date: 2022.12.29 FOX FACTORY INC

AI summary

Described herein is a fluid flow control device comprising: a central structure, a main piston disposed around the central structure, wherein the main piston has at least one vent, a boost valve, wherein the boost valve has a gap fit to receive fluid, a shim stack disposed between the main piston and the boost valve such that the at least one vent is covered, a piston disposed on top of the gap of the boost valve, a spring disposed to bias the piston against the boost valve, and a pilot chamber running through the central structure, the pilot chamber fluidly coupled to the gap.