Leaning Vehicle Frame Coupling for Torsional Rigidity
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Solution Overview
Problem
Existing leaning vehicles face challenges in increasing the maximum leaning angle without enlarging the vehicle body frame, which affects running speed and stability, particularly due to uneven road surface conditions causing torsional forces that lead to frame deflection and reduced rigidity.
Innovation Solution
The design incorporates a coupling frame that extends parallel to the up-down direction of the vehicle body frame to reduce the size of the frame structure surrounding the rear element, enhancing rigidity and allowing closer placement of the coupling frame to the rear element of the lower cross member, thereby suppressing deflection and torsional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the frame structure is enlarged to increase the maximum leaning angle, then the bank angle can be increased, but the vehicle body frame size becomes larger
Solution Approach 1:
The frame structure is divided into upper frame and lower frame sections that can move relative to each other through the link mechanism, allowing the frame to segment and reconfigure during leaning operations, enabling greater lean angles without proportionally increasing overall frame size
Solution Approach 2:
The frame structure transitions from a static configuration to a dynamic one where the upper and lower frames can rotate relative to each other via the link mechanism, allowing the frame shape to change during operation to achieve larger lean angles while maintaining compact dimensions
2Strength
If the frame structure is made more rigid to handle torsional forces, then stability improves, but the frame becomes more complex and larger
Solution Approach 1:
The coupling frame is positioned in advance to directly connect the upper and lower frames at strategic locations, creating pre-established rigid connections that resist torsional forces before they occur during uneven road operation, eliminating the need for additional complex bracing structures
Solution Approach 2:
The coupling frame merges the upper and lower frame structures into a unified rigid assembly, combining their load-bearing capabilities to resist torsional forces effectively while maintaining structural simplicity through integration rather than adding separate reinforcement components
Data Source
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AI summary
A link mechanism (5) includes a lower cross member (52) supported by a link support portion (212) and provided with a rear element (522). The rear element (522) is turnable about a turning axis at a position behind the link support portion (212). The body frame (21) includes an upper frame (213U), a lower frame (213D) and a coupling frame (213C). The upper frame (213U) and the lower frame (213D) extend rearward from the link support portion (212) so as to intersect areas respectively lying directly above and below a turning range of the rear element (522). A longitudinal direction of the coupling frame (213C) follows an up-down direction of the body frame (21). The coupling frame (213C) couples the upper frame (213U) and the lower frame (213D) together at a position behind the rear element (522). A majority of a front edge (213C1) of the coupling frame (213C) extends along the longitudinal direction as viewed from a left-right direction of the body frame (21) when the leaning vehicle (1) is in an upright condition.