Weight-Shifting Vehicle Steering Axle Geometry

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Solution Overview

Problem

Existing vehicles that steer by weight shifting, such as recumbent bikes and scooters, lack comfort and reliability at higher speeds, requiring users to hold onto handlebars and have large turning circles, limiting maneuverability and hands-free operation.

Innovation Solution

A vehicle design with a steering axis positioned close to the rear axle, allowing weight shifting to control direction without articulated steering, incorporating friction-reducing means and a restoring element to maintain stability and enable hands-free operation at higher speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If articulated steering systems are used with distance between pivot point and steering axis greater than rear wheel radius, then steering by weight shifting is achieved, but wheelbase becomes long resulting in large turning circle

Engineering Contradiction:
Improveweight shifting steeringVSAvoidwheelbase
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The invention extracts and eliminates the intermediate lever arm (articulated steering mechanism) between the rear axle pivot point and the steering axis. By positioning the steering axis directly at or near the rear axle pivot point (distance less than or equal to rear wheel radius), the patent removes the unnecessary structural extension that caused the long wheelbase, while preserving the weight-shifting steering functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of having the steering axis positioned far from the rear axle as in conventional articulated steering, the invention inverts this arrangement by placing the steering axis at or near the rear axle pivot point. This inversion of the traditional steering geometry fundamentally reduces the wheelbase length while maintaining steering capability through weight shifting.

Inventive Principle:
Principle #13The other way round (Inversion)

2Ease of operation

If conventional recumbent bicycles with handlebars are used, then comfortable seating position is achieved, but hands are not free for other tasks

Engineering Contradiction:
Improvecomfortable seating positionVSAvoidhands-free operation
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The vehicle enables self-steering through the rider's natural weight shifting movements. The steering system responds automatically to the rider's body movements without requiring manual input via handlebars, making the system serve itself through the rider's inherent motions rather than requiring additional control mechanisms.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention replaces the manual mechanical steering system (handlebars requiring hand operation) with an automatic weight-shift-based steering mechanism. This substitution eliminates the need for manual handlebar operation while maintaining steering control, freeing the rider's hands for other activities.

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

3Adaptability or versatility

If weight shifting steering is used at high speeds, then hands-free operation is achieved, but steering reliability becomes poor and falls occur

Engineering Contradiction:
Improvehands-free operationVSAvoidsteering reliability at high speed
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention changes the geometric parameters of the steering system, specifically positioning the steering axis at or near the rear axle pivot point (distance less than or equal to rear wheel radius). This parameter change creates a more stable and responsive steering characteristics that maintains reliability at higher speeds while preserving hands-free weight-shift operation capability.

Inventive Principle:
Principle #35Parameter changes

4Stability of the object's composition

If conventional three-wheeled recumbent bicycles are used, then stable structure is achieved, but track width must be wide resulting in large turning circle

Engineering Contradiction:
Improvevehicle stabilityVSAvoidtrack width
Core Design Contradiction:
Stability of the object's compositionVSLength of moving object

Solution Approach 1:

The invention shifts the stability mechanism from a wide lateral track width to a different dimensional approach by optimizing the steering geometry (steering axis position at or near rear axle). This allows the vehicle to achieve stability through improved steering response and weight distribution rather than relying on a wide track, effectively solving the problem in a different dimensional space.

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

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 vehicle achieves a smaller turning circle, increased cornering speed, and improved stability by allowing safe steering by weight shifting at higher speeds, keeping hands free for other activities and enhancing maneuverability in tight spaces.

Implementation Method 1

at least one restoring element, wherein the steering axle has an inclination of 20° to 80°, in particular 40° to 70°, to the horizontal, and wherein the at least one restoring element is arranged such that the restoring element exerts a restoring force on a pivoting deflection of the axle

Methodology Applied
Scientific EffectRestoring force: Elasticity

Implementation Method 2

at least two friction-reducing means attached to a common axle, in particular rear axle, and/or common rigid transverse structure and/or rigidly connected to each other

Methodology Applied
Scientific EffectFriction reduction: Friction

Data Source

PatentEP3514044B1Vehicle
Publication Date: 2021.09.15 BIELFELDT HOLM
  • EP3514044B1 patent drawingFigure 1~3
  • EP3514044B1 patent drawingFigure 4~6
  • EP3514044B1 patent drawingFigure 7~9

AI summary

The present invention relates to a vehicle steerable by weight shifting and to a steering method. Steering vehicles by weight shifting is known. The invention is based on the objective of enabling a comfortable seating position while driving without the need for the hands and of enabling safe driving at speeds above 20 km/h.The problem is solved in the vehicle by a steering axle (3) which has an inclination of 20° to 80° to the horizontal, at least one damping and/or restoring element (5) which exerts a damping and/or restoring force on a deflection of the axle, in particular the rear axle, wherein the damping and/or restoring force runs in a plane perpendicular to the steering axle (3) or at an angle of less than 30°, in particular less than 20°, to the plane perpendicular to the steering axle (3) and/or the damping and/or restoring element (5) with its longitudinal extension runs in a plane perpendicular to the steering axle (3) or at an angle of less than 30° to the plane perpendicular to the steering axle (3).