Telescopic Fork Anti-Dive Cam Linkage

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Solution Overview

Problem

Existing telescopic front suspension systems experience excessive dive during braking, leading to reduced control and increased risk of rear wheel detachment due to stiffened suspension to mitigate this, which results in loss of front tire grip and adherence to the road.

Innovation Solution

A telescopic front suspension system with an anti-dive effect that utilizes a cam profile with a variable eccentricity guide to transfer a portion of the braking force along the fork axis, opposing compression and controlling dive through a mechanical connection between the braking device and the suspension, allowing for adjustable antidive thrust based on fork stroke.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the suspension is stiffened to prevent excessive dive, then the dive control is improved, but the front tire grip and adherence to the road surface are reduced

Engineering Contradiction:
Improvedive controlVSAvoidfront tire grip
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent implements a dynamic antidive system where the mechanical linkage between the brake caliper and fork adjusts the antidive effect based on braking intensity and fork position. The system transitions from a static suspension setup to a dynamic one that adapts in real-time, allowing optimal dive control without compromising tire grip under different operating conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of suspension stiffness from a fixed value to a variable parameter that adjusts according to braking conditions. Through the mechanical linkage involving the brake caliper, pivot points, and fork, the system varies the antidive moment arm length and force transmission ratio dynamically, enabling soft suspension during normal riding and stiff suspension during braking without sacrificing grip.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If a cam profile with variable eccentricity is used, then the antidive thrust becomes adjustable based on fork stroke, but the device complexity increases

Engineering Contradiction:
Improveantidive thrust adjustmentVSAvoidmechanical connection structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent employs a cam profile with variable eccentricity that uses curved geometric surfaces to achieve variable antidive thrust. The cam's eccentricity varies along its rotation path, creating a mechanical advantage ratio that changes with fork position. This curved geometry approach provides continuous adjustment capability without requiring complex electronic control systems or multiple adjustable components.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The mechanical linkage system automatically adjusts the antidive effect based on the braking force applied and fork position, without requiring external control inputs. The system uses the braking force itself as the control signal, where the brake caliper's position and the linkage geometry automatically determine the appropriate antidive thrust, making the system self-regulating and reducing control complexity.

Inventive Principle:
Principle #25Self-service

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 effectively reduces and controls front suspension dive, maintaining vehicle balance and responsiveness while preventing excessive stiffness that compromises tire grip, allowing for calibrated antidive effect depending on braking conditions.

Implementation Method 1

A telescopic front suspension system with an anti-dive effect that utilizes a cam profile with a variable eccentricity guide to transfer a portion of the braking force along the fork axis

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

transfer a portion of the braking force along the fork axis, opposing compression and controlling dive through a mechanical connection between the braking device and the suspension

Methodology Applied
Scientific EffectMechanical force transfer: Mechanical Force

Data Source

PatentUS11396342B2Front suspension of the telescopic type with anti-dive effect
Publication Date: 2022.07.26 PIAGGIO & C SPA
  • US11396342B2 patent drawing
  • US11396342B2 patent drawing
  • US11396342B2 patent drawing

AI summary

A front suspension (4) of the telescopic type with anti-dive effect, comprising at least one sheath (32) and at least one stem (36), housed and guided telescopically inside said sheath (32) according to a direction of the fork axis Z-Z, the suspension (4) comprising a foot (44) associated to the sheath (32) or to the stem (36) that rotatably supports a wheel spindle (44) of an associable front wheel (12) defining a rotation axis X-X, a braking device (52) for the associable front wheel (12), having a support (56) rotatably mounted with respect to the wheel spindle (44) so as to be able to oscillate about the rotation axis X-X. Between the support (56) of the braking device (52) and the foot (44) of the suspension (4) are interposed transfer means (64) of the braking force, exerted by the braking device (52), on an element (32, 36) between the sheath (32) and the stem (36) that does not support the foot (44). Said transfer means (64) comprise a cam (68) hinged to the foot (44) in a first hinge point (72), kinematically connected to the braking means, and mechanically connected to a portion of the suspension (4) integral with the element (32, 36) between the sheath (32) and the stem (36) that does not support (56) the foot (44) so as to transfer thereto, in the direction of the fork axis Z-Z, a part of the braking force.