Boost Valve Damping Control to Prevent Shock Absorber Oscillation

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Solution Overview

Problem

Conventional shock absorbers face issues with constant damping rates and mechanical complexities, leading to overshoot and oscillation during sudden terrain changes, resulting in a harsher riding experience and increased manufacturing costs.

Innovation Solution

A fluid flow control device with a main piston, boost valve, shim stack, and spring mechanism that allows fluid flow control without volume change, preventing hydro locking and oscillation, and featuring a pilot chamber and o-rings for improved pressure management and smoother operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional shock absorbers use constant damping rate mechanisms, then the structure is simple, but the riding comfort deteriorates during sudden terrain changes

Engineering Contradiction:
Improveriding comfortVSAvoiddamping control mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The shock absorber transitions from constant damping to variable damping by using a boost valve mechanism that dynamically adjusts damping rates based on fluid pressure changes during compression and rebound strokes, improving riding comfort without requiring complex electronic controls

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention uses hydraulic fluid pressure dynamics to control the boost valve, which adjusts the damping rate by opening or closing flow paths based on pressure thresholds, eliminating the need for mechanical linkages or electronic sensors

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Reliability

If shock absorbers use mechanical damping variation mechanisms, then damping rate can be varied, but overshoot and oscillation occur during sudden terrain changes

Engineering Contradiction:
Improvedamping stabilityVSAvoidresponse smoothness
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention replaces traditional mechanical damping adjustment mechanisms with a hydraulic boost valve system that uses fluid pressure to control damping rates, eliminating mechanical overshoot and oscillation through smoother pressure-based transitions

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The boost valve changes the damping parameter dynamically by opening or closing flow paths based on fluid pressure thresholds during compression and rebound, providing stable and smooth damping variation without mechanical oscillation

Inventive Principle:
Principle #35Parameter changes

3Reliability

If shock absorbers use complex sealing mechanisms, then fluid leakage is prevented, but manufacturing costs increase

Engineering Contradiction:
Improvesealing effectivenessVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention uses flexible O-ring seals instead of complex multi-component sealing mechanisms, achieving effective sealing while simplifying manufacturing and reducing costs through the use of elastomeric sealing elements

Inventive Principle:
Principle #30Flexible shells and thin films

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 provides a variable damping rate, reduces overshoot and oscillation, and simplifies the design, resulting in a smoother ride and lower manufacturing costs by preventing fluid volume changes during sudden events and eliminating the need for complex O-ring sealing.

Implementation Method 1

a spring disposed to bias said piston against said boost valve

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

after a pressure threshold is reached fluid flow through said vent will open said shim stack, which in turn will raise said boost valve

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP4108955A1Fluid flow control device
Publication Date: 2022.12.28 FOX FACTORY INC
  • EP4108955A1 patent drawingFigure 1
  • EP4108955A1 patent drawingFigure 2
  • EP4108955A1 patent drawingFigure 3

AI summary

A fluid flow control device (100) comprising: a central structure (101); a main piston (103) disposed around said central structure, wherein said main piston has at least one vent (104); a boost valve (107), wherein said boost valve has a gap (108) fit to receive fluid; a shim stack (106) disposed between said main piston (103) and said boost valve (109) such that said at least one vent (104) is covered; a piston (109) disposed on top of said gap (108) of said boost valve (107); a spring (110) disposed to bias said piston against said boost valve; and a pilot chamber running through said central structure, said pilot chamber fluidly coupled to said gap.