Bypass Port Piston Layout for Bottom-Out and Top-Out Damping

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Solution Overview

Problem

Conventional shock absorbers face issues with bottoming out and topping out, leading to rider discomfort and potential damage, and have excessive dead length, especially in vehicles with limited packaging space.

Innovation Solution

A bypass port piston with face shims and check springs that restrict fluid flow through standard ports, utilizing position-sensitive and velocity-sensitive mechanisms to control fluid flow direction and prevent bottoming out and topping out, reducing dead length and manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional shock absorbers use standard ports for fluid flow, then manufacturing is simpler, but bottoming out and topping out occur causing rider discomfort and potential damage

Engineering Contradiction:
Improveprevention of bottoming out and topping outVSAvoidrider discomfort and shock damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The piston is divided into multiple functional sections with different port types (standard ports and bypass ports). The bypass ports are positioned at specific locations on the piston to allow fluid communication between chambers during extreme compression or extension, preventing bottoming out and topping out while maintaining standard manufacturing processes for the majority of the piston structure.

Inventive Principle:
Principle #1Segmentation

2Reliability

If shock absorbers include bypass ports, then bottoming out and topping out are prevented, but dead length increases reducing packaging efficiency

Engineering Contradiction:
Improveprevention of bottoming out and topping outVSAvoiddead length
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

Instead of extending the piston length axially to accommodate bypass mechanisms, the bypass ports are integrated into the piston's radial or circumferential surface. This dimensional repositioning allows fluid bypass functionality without increasing the piston's axial length, thereby preventing bottoming out and topping out while minimizing dead length for compact packaging.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If bypass ports are added to the piston, then shock absorber performance is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveshock absorber performanceVSAvoidpiston manufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The bypass ports serve multiple functions: they prevent bottoming out during compression, prevent topping out during extension, and maintain fluid communication between chambers. By designing the bypass ports to fulfill multiple protective functions simultaneously, the need for separate mechanical stops or additional complex mechanisms is eliminated, improving overall shock absorber performance while keeping the piston manufacturing process relatively simple.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 reduces the likelihood of shock absorber damage and rider discomfort by varying damping rates and minimizing dead length, while maintaining performance without adding bleed to the system.

Implementation Method 1

at least one check spring coupled to the main damping piston... The at least one check spring may keep the at least one check shim in an open position (including biasing the at least one check shim toward an open position)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a position sensitive spring disposed to close the check shim as the main damping piston is pressed against the position sensitive spring

Methodology Applied
Scientific EffectPressure: Pressure Increase

Implementation Method 3

face shims disposed on at least one side of the main damping piston such that fluid flow through the plurality of standard ports is restricted

Methodology Applied
Scientific EffectFluid resistance: Drag

Data Source

PatentEP4148297A1Bypass port piston
Publication Date: 2023.03.15 FOX FACTORY INC
  • EP4148297A1 patent drawingFigure 1
  • EP4148297A1 patent drawingFigure 2
  • EP4148297A1 patent drawingFigure 3

AI summary

A bypass port piston comprising: a main damping piston (108), wherein the main damping piston has a plurality of standard ports (102), wherein the main damping piston has at least one bypass port (218); face shims (110, 112) disposed on at least one side of the main damping piston such that fluid flow through the plurality of standard ports (102) is restricted; at least one check spring (220) coupled to the main damping piston (108); at least one check shim (222) disposed to cover the at least one bypass port (218) and coupled to the at least one check spring (220), wherein the at least one check spring biases the at least one check shim toward an open position; and a position sensitive spring (224) disposed to close the at least one check shim (222) as the main damping piston (108) is pressed against the position sensitive spring (224).