Motorcycle Swing Arm Pivot Axis Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rigid frame motorcycles lack rear wheel suspension, resulting in a poor ride and handling issues, especially in bumpy conditions and during cornering, making them uncomfortable for riders, particularly older ones.
Innovation Solution
A suspension system for the rear wheel of a motorcycle that includes a swing arm pivotally connected to the frame with a shock absorber arrangement, allowing pivotal movement about a first pivot axis located between the connection points to the rear wheel axle and the suspension, providing effective suspension and damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a rigid frame motorcycle is used, then the design simplicity and low weight are achieved, but the ride comfort and handling are poor
Solution Approach 1:
The swing arm is divided into two separate side members (first and second side members) that are pivotally connected to the frame independently. This segmentation allows each side member to move separately to accommodate suspension movement while maintaining the overall rigid frame appearance and structural simplicity.
Solution Approach 2:
The swing arm side members are designed to pivot dynamically about the first pivot axis relative to the frame, allowing the rear wheel assembly to move vertically for suspension while the pivot axis remains fixed. This dynamic movement provides ride comfort without requiring a completely flexible frame structure.
2Ease of operation
If a conventional swing arm suspension system is used, then ride comfort is improved, but the rigid frame appearance is lost
Solution Approach 1:
The pivot axis is positioned locally between the axle connection point and the suspension connection point on the swing arm. This specific local positioning allows the suspension components to be arranged in a compact configuration that does not protrude outward, maintaining the clean lines and appearance of a rigid frame while providing suspension functionality.
Solution Approach 2:
The suspension connection is arranged along the longitudinal axis of the motorcycle rather than extending outward laterally. By positioning the third location (suspension connection) along the length of the swing arm rather than at its outer end, the suspension components are integrated into the longitudinal dimension, preserving the external appearance.
3Length of moving object
If the pivot axis is positioned at the outer end of the swing arm, then the suspension travel is maximized, but the axle twist increases
Solution Approach 1:
The pivot axis is positioned in advance between the axle and suspension connection points rather than at the outer end. This preliminary positioning of the pivot axis creates a shorter moment arm for lateral forces, preventing axle twist before it can occur during cornering or bump absorption.
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 enhances ride comfort and handling by absorbing bumps and reducing axle twist, maintaining the rigid frame appearance while improving ride quality and control.
Implementation Method 1
said swing arm arranged for connection at a third location to a suspension arrangement... supported by springs or shock absorbers... dampening of the movement of the rear axle
Data Source
AI summary
The present invention relates to a suspension system for a motorcycle and to frames incorporating such a suspension system. The suspension system includes a swing arm arranged for pivotal movement about a first pivot axis. The swing arm is also arranged for connection at a second location via respective axle plates to a rear wheel axle of the motorcycle. The swing arm is arranged for connection at a third location to a suspension arrangement in the form of a shock absorber arrangement. The first pivot axis is located between the second and third locations.