Hub Center Steering Layout for Three-Wheel Motorcycle Packaging

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Solution Overview

Problem

Conventional vehicles with a front fork mechanism directly connecting the wheel and handlebar lack design flexibility due to the absence of a space between the handlebar and wheel, limiting design freedom.

Innovation Solution

A vehicle design incorporating a hub center steering mechanism with swing arms and a steering link that allows a space to be formed between the handlebar and front wheel, enabling installation of components like a storage battery or control device, and featuring a caster angle adjustment mechanism for improved stability and mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a front fork mechanism is used to directly connect the wheel and handlebar, then the steering function is achieved, but the space between the handlebar and wheel is eliminated reducing design freedom

Engineering Contradiction:
Improvedesign freedomVSAvoidspace between handlebar and wheel
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The front fork mechanism is divided into separate functional components: the handlebar assembly, the steering crown, and the wheel hub assembly. This segmentation allows the space between the handlebar and wheel to be utilized for mounting storage batteries, control devices, or other components while maintaining the steering function through the crown's rotation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention utilizes the vertical space dimension between the handlebar and wheel that was previously unused. By mounting components in this vertical gap rather than along the horizontal axis, the design creates new spatial utilization without interfering with the steering mechanism's horizontal rotation.

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

2Stability of the object's composition

If the caster angle is increased for forward traveling stability, then stability is improved, but mobility during turning deteriorates

Engineering Contradiction:
Improveforward traveling stabilityVSAvoidturning mobility
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The caster angle is made dynamically adjustable rather than fixed. The system automatically changes the caster angle based on the vehicle's operating state: a larger caster angle is provided during forward traveling for stability, while a smaller caster angle is provided during turning for improved mobility. This dynamic adjustment resolves the contradiction between stability and maneuverability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The caster angle parameter is changed according to the vehicle's traveling state. By detecting whether the vehicle is in forward traveling or turning mode, the system adjusts the caster angle parameter accordingly, optimizing both stability and mobility performance for different operating conditions.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4725818A1vehicle
Publication Date: 2026.04.15 CHIBA INSTITUTE OF TECHNOLOGY
  • EP4725818A1 patent drawingFigure 1
  • EP4725818A1 patent drawingFigure 2
  • EP4725818A1 patent drawingFigure 3

AI summary

Provided is a vehicle configured so that a space can be formed between a handlebar and a wheel and the degree of freedom in designing the vehicle can be improved. A three-wheeled motorcycle 1 includes a saddle 2 on which a human body is seated, at least three wheels 3 having a pair of left and right front wheels 31 and a rear wheel 32, a handlebar 4 that steers the wheels 3, and a frame 5 supporting the wheels 3 and the handlebar 4. The three-wheeled motorcycle 1 includes a hub center steering mechanism having a pair of left and right swing arms 51 supported by the frame 5 and swinging the front wheels 31 in an up-down direction and a steering link 53 connecting the handlebar 4 and hubs of the front wheels 31 and steering the front wheels 31 based on operation of the handlebar 4.