Front Wheel Support Structure for Straddle-Type Vehicle
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Solution Overview
Problem
Conventional front wheel supporting structures for straddle-type vehicles increase vehicle weight and rigidity due to the longitudinal extension of link members, leading to increased weight and reduced maneuverability, and require higher spring and damper forces to prevent front dive during braking.
Innovation Solution
A front wheel supporting structure that reduces the rigidity of the vehicle body-configuring member by using a front arm with a compression load in its length direction during braking, suppressing turning motion of the front arm, and employing a resiliently supported rear end of the front arm to minimize link member load and weight, allowing for a more centralized barycenter and simplified link member shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the link members extend long in the longitudinal direction to support the front wheel, then the rigidity of the link mechanism is increased, but the weight of the front portion of the vehicle is increased
Solution Approach 1:
The link mechanism is divided into multiple link members (first link member, second link member, third link member) connected in series. This segmentation allows the load to be distributed across multiple shorter members rather than requiring one long member, reducing overall weight while maintaining rigidity through the combined structure.
Solution Approach 2:
The link members are arranged in a multi-dimensional configuration rather than extending purely in the longitudinal direction. The first link member extends in the longitudinal direction, the second link member extends in the vehicle width direction, and the third link member connects back to the front arm. This spatial arrangement achieves the required support function with shorter individual members, reducing weight while maintaining structural rigidity.
2Reliability
If the rigidity of the vehicle body-configuring member is increased to prevent front dive during braking, then the durability is enhanced, but the weight of the vehicle is increased
Solution Approach 1:
The braking load is segmented and transmitted through multiple link members rather than directly to the vehicle body-configuring member. The first link member receives the load from the front arm, the second link member transfers it laterally, and the third link member completes the load path. This segmentation reduces the peak load and rigidity requirements for the vehicle body-configuring member, allowing weight reduction while maintaining durability.
3Stability of the object's composition
If the link members are made heavier and more rigid to support the front wheel, then the stability is improved, but the maneuverability of the vehicle is reduced
Solution Approach 1:
The multi-link mechanism segments the support function across multiple lighter members rather than relying on one heavy rigid structure. This allows the front wheel to be supported stably while reducing the overall mass that would hinder maneuverability.
Solution Approach 2:
The link members are configured to allow controlled movement and adjustment during vehicle operation. The multi-link mechanism can dynamically adapt to different loading conditions and steering angles, maintaining stability when needed while enabling easy maneuvering when required, without the penalty of excessive weight.
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 configuration reduces vehicle weight, enhances durability, minimizes the front dive phenomenon, and allows for reduced spring and damper forces, improving ride quality and impact resistance while maintaining effective steering and stability.
Implementation Method 1
most of a load (reaction force from road surface) applied to the front wheel at the time of braking can be received by a compression load in a length direction of the front arm
Implementation Method 2
employing a resiliently supported rear end of the front arm to minimize link member load and weight
Data Source
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AI summary
A front wheel supporting structure for a straddle-type vehicle includes a front arm (10) which supports a front axle (6) and which extends rearward from a front axle to a location behind a front wheel (5), and a pair of upper and lower link members (21, 22) which is turnably connected to two vertically separated portions of a rear end of a front arm (10). The link members (21, 22) extend rearward. Rear ends (21b, 22b) of the link members are turnably connected to a vehicle body-configuring member. The front wheel supporting structure includes a front suspension mechanism (12) which suppresses turning motion of the front arm (10).