Watt Four-Bar Front Suspension to Reduce Rubbing and Bouncing

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Solution Overview

Problem

Saddle-riding motor vehicles face issues with front suspensions that allow non-rectilinear movement of the front steered wheel due to uneven ground and braking forces, leading to transverse rubbing and bouncing problems, which existing suspensions with revolute pairs cannot adequately address.

Innovation Solution

A suspension system incorporating a Watt four-bar linkage that connects the front steered wheel to a rotatable arm, allowing the wheel support to move in a substantially rectilinear trajectory during springing movements, combining the advantages of telescopic forks and kinematic mechanisms with revolute pairs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If suspensions use revolute pairs with four-bar linkage to connect sprung mass and unsprung mass, then the advantages of revolute pairs are achieved, but the axle of the wheel carries out non-rectilinear movement causing transverse rubbing and bouncing problems

Engineering Contradiction:

Improveadvantages of revolute pairsVSAvoidtransverse rubbing and bouncing

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The invention introduces a prismatic pair (sliding connection) between the lower arm and the axle support, adding a dimensional constraint that forces rectilinear movement of the wheel axle. This combines the rotational degrees of freedom of revolute pairs with the translational constraint of a prismatic pair, achieving both the advantages of revolute pairs and eliminating non-rectilinear movement effects.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If telescopic forks with sliding members are used to allow relative movement between handlebar and steering column, then relative movement is achieved, but problems typical of cylindrical pairs occur

Engineering Contradiction:

Improverelative movement between handlebar and steering columnVSAvoidproblems typical of cylindrical pairs

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The invention replaces the cylindrical pair (telescopic fork sliding mechanism) with a prismatic pair (sliding connection between lower arm and axle support). This substitution maintains the relative movement capability while eliminating the harmful effects associated with cylindrical pairs, such as lateral play and instability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4028317B1A motor vehicle with a suspension using a watt four-bar linkage

Publication Date: 2023.08.23 PIAGGIO & C SPA

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AI summary

The saddle-riding motor vehicle (1; 107; 207) comprises a rear driving wheel (5; 105; 205) and a front steered wheel (7; 107; 207). The front steered wheel (7; 107; 207X, 207Y) is connected to a rotatable arm (9; 109; 209X, 209Y) provided with a rotary motion about a steering axis (A-A). A wheel support (37; 137) is connected to the rotatable arm (9; 109; 209) with the interposition of a suspension (17; 117; 217X, 217Y) comprising a shock absorber (22; 122). The suspension (17; 117) comprises a Watt four-bar linkage.