Shock Assembly With Automatic Ride Height Adjustment

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Solution Overview

Problem

Vehicle suspension systems face challenges in maintaining optimal ride height when additional weight is added, leading to changes in vehicle geometry, steering issues, and increased stiffness, as existing systems require manual adjustment or component replacement to accommodate varying rider weights.

Innovation Solution

A shock assembly with a tube-in-shaft pump assembly and spring preload piston assembly that automatically adjusts ride height by pumping fluid into or out of a spring preload piston chamber, using a valve and bleed orifice to control fluid flow, allowing for dynamic adjustment of ride height while maintaining damping settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the shock assembly is set to a softer setting for a lighter rider, then ride comfort is improved, but the available travel is reduced when a heavier rider uses it

Engineering Contradiction:
Improveride comfortVSAvoidavailable travel
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The shock assembly incorporates an automatic ride height adjustment assembly that dynamically changes the spring preload based on the actual load applied to the vehicle. The system uses a pump tube with an intake/exhaust port that responds to compression stroke conditions, automatically adjusting fluid volume in the spring preload piston assembly to maintain optimal ride height and available travel regardless of rider weight

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the physical state of the suspension system by varying the spring preload force through fluid volume adjustment. By controlling the axial location of the intake/exhaust port and the amount of fluid in the spring preload piston assembly, the system dynamically modifies the effective spring rate and ride height parameters to accommodate different load conditions

Inventive Principle:
Principle #35Parameter changes

2Length of moving object

If the shock assembly is set to a harder setting for a heavier rider, then available travel is improved, but ride comfort deteriorates when a lighter rider uses it

Engineering Contradiction:
Improveavailable travelVSAvoidride comfort
Core Design Contradiction:
Length of moving objectVSEase of operation

Solution Approach 1:

The automatic ride height adjustment assembly dynamically adapts the suspension characteristics by responding to the actual compression stroke conditions. The pump tube mechanism automatically adjusts fluid volume based on the load-induced compression, transforming the static suspension setup into a dynamic system that optimizes both available travel and ride comfort for the current rider weight

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system self-adjusts by using the compression stroke itself as the triggering mechanism. The pump tube intake/exhaust port automatically responds to the compression conditions without external intervention, allowing the shock assembly to self-regulate its ride height and spring preload based on the actual load being carried

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If manual adjustment or component replacement is used to accommodate varying rider weights, then ride height optimization is achieved, but device complexity and adjustment time increase

Engineering Contradiction:
Improveride height optimizationVSAvoidadjustment mechanism
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system eliminates manual adjustment by implementing a self-regulating mechanism where the pump tube and intake/exhaust port automatically respond to load conditions. The shock assembly self-adjusts its ride height by controlling fluid volume in the spring preload piston assembly based on the actual compression stroke, removing the need for manual intervention or complex adjustment mechanisms

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system incorporates implicit feedback through the pump tube mechanism that monitors compression stroke conditions and automatically adjusts fluid volume accordingly. The intake/exhaust port position and the resulting fluid transfer create a closed-loop response that maintains optimal ride height based on actual load conditions

Inventive Principle:
Principle #23Feedback

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 system automatically returns the vehicle to its pre-established ride height (SAG) when additional weight is added or removed, improving stability and reducing the risk of steering problems, suspension bottom-out, and tire blowouts, without requiring manual adjustment or component replacement.

Implementation Method 1

an axial motion of said damping piston and said shaft along said pump tube during a compression stroke pumps said fluid through said pump tube and into said spring preload piston assembly

Methodology Applied
Scientific EffectHydraulic pumping: Pump

Implementation Method 2

a valve to control said fluid returning from said spring preload piston assembly to said pump tube via said fluid path

Methodology Applied
Scientific EffectHydraulic pressure control: Pressure Gradient

Implementation Method 3

a bleed orifice to control a rate of bleed from said spring preload piston assembly

Methodology Applied
Scientific EffectOrifice flow control: Pressure Drop

Data Source

PatentEP3875801B1A shock assembly and method
Publication Date: 2024.09.04 FOX FACTORY INC
  • EP3875801B1 patent drawingFigure 1A
  • EP3875801B1 patent drawingFigure 1B
  • EP3875801B1 patent drawingFigure 2A

AI summary

A shock assembly (100) comprising: a main chamber (220) comprising a fluid therein; a pump tube (250) within said main chamber (220), said pump tube having a fluid flow path internal thereto, said pump tube disposed axially along a center of said main chamber; a damping piston (210) coupled to a shaft (130), said damping piston and a portion of said shaft disposed axially about said pump tube (250), said damping piston (210) disposed in said main chamber to divide said main chamber into a compression side fluid chamber and a rebound side fluid chamber; and an automatic ride height adjustment assembly comprising: a tube-in-shaft pump assembly (251); and a spring preload piston assembly (266).