Motorcycle Front Wheel Guide With Roller-Bearing Ball Joint

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Solution Overview

Problem

Existing front wheel guides for single-track motor vehicles face a trade-off between minimizing friction torque for precise low-speed handling and maximizing rigidity for high-speed stability, with current ball joints struggling to optimize both simultaneously.

Innovation Solution

Incorporating two roller bearings to support the trailing arm on a ball joint pin, with radially extending projections and an engagement ring to optimize friction torque and stiffness independently, while sealing the connection area to prevent contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a ball joint is installed on the lower triple clamp to ensure kinematic clearance, then high rigidity is achieved for driving stability at high speeds, but high frictional moment occurs about the steering axis, degrading precise driving feel at low speeds

Engineering Contradiction:
Improvedriving stabilityVSAvoidfrictional moment
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The ball joint assembly is segmented into multiple functional components: the ball joint itself for providing rigidity and stability, and a separate friction element (friction ring or friction plate) specifically designed to generate controlled frictional moment. This segmentation allows each component to independently fulfill its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A friction element is introduced as an intermediary component between the ball joint and the steering mechanism. This friction element acts as a mediator that provides the necessary frictional moment for precise low-speed handling while allowing the ball joint to maintain its rigidity for high-speed stability. The friction element can be a friction ring positioned around the ball joint pin or a friction plate integrated into the triple clamp assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If high preload is applied in the ball joint to achieve high rigidity, then driving stability at high speeds is improved, but frictional moment about the joint axis increases, reducing target accuracy at low speeds

Engineering Contradiction:
Improvedriving stabilityVSAvoidtarget accuracy
Core Design Contradiction:
Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The preload function is segmented and assigned to the friction element rather than the ball joint itself. The ball joint is designed with optimal preload for rigidity and stability, while the friction element provides additional controlled friction to enhance precision. This segmentation allows independent optimization of each component's preload characteristics.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The frictional characteristics are changed by introducing a dedicated friction element with specific friction properties. By adjusting the friction element's material, geometry, and positioning, the frictional moment can be precisely controlled to improve target accuracy without affecting the ball joint's rigidity parameters. The friction element can be designed with specific surface properties or adjustable preload mechanisms to fine-tune the frictional moment.

Inventive Principle:
Principle #35Parameter changes

3Force

If the ball joint geometry and preload are adjusted to minimize friction torque, then low-speed handling precision is improved, but rigidity decreases, compromising high-speed stability

Engineering Contradiction:
Improvefriction torqueVSAvoidhigh-speed stability
Core Design Contradiction:
ForceVSStability of the object's composition

Solution Approach 1:

The friction management function is segmented into a dedicated friction element that works in conjunction with the ball joint. The ball joint geometry and preload are optimized for minimum friction and maximum rigidity, while the friction element provides the necessary frictional moment for precision. This segmentation eliminates the need to compromise ball joint rigidity to reduce friction torque.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The friction element serves as an intermediary that decouples the relationship between friction torque and rigidity. It provides the frictional moment needed for precision handling without interfering with the ball joint's rigidity characteristics. The friction element can be positioned to engage only during specific operating conditions, allowing the ball joint to maintain optimal rigidity across all operating ranges.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This design minimizes friction torque for improved low-speed accuracy, optimizes high-speed stability, extends ball joint lifespan by allowing independent stiffness adjustment, and enhances service life by reducing play in the ball joint.

Implementation Method 1

The trailing arm is rotatably mounted on the ball joint by means of two rolling bearings

Methodology Applied
Scientific EffectRolling friction: Roller

Implementation Method 2

the friction torque around the ball joint is minimized by an additional roller bearing

Methodology Applied
Scientific EffectFriction reduction: Friction

Data Source

PatentEP4054868B1Front wheel guide for a single-track motor vehicle
Publication Date: 2024.03.06 BAYERISCHE MOTOREN WERKE AG
  • EP4054868B1 patent drawingFigure 1
  • EP4054868B1 patent drawingFigure 2

AI summary

The invention relates to a front wheel guide (1) for a single-track motor vehicle, comprising a telescopic fork (2), a fork bridge (6) and a longitudinal control arm (7). The telescopic fork (2) has two fork bars (3), which each comprise a lower fork tube (4) and an upper fork tube (5), which can be slid relative to the lower fork tube. The fork bridge (6) extends in a transverse direction (Q) and interconnects the lower fork tubes (4) of the fork bars (3). The longitudinal control arm (7), which is pivotably articulated to the motorcycle, is connected to the fork bridge (6) by means of a ball joint (8). The front wheel guide is characterized in that the longitudinal control arm (7) is rotatably mounted on the ball joint (8) by means of at least one rolling element bearing (9).