Saddle Riding Vehicle Frame Truss Structure
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Solution Overview
Problem
The existing vehicle body frame structures of saddle riding vehicles, particularly those with truss frames, suffer from high rigidity which leads to increased weight and compromised steering stability due to a long distance from the torsional center to the front wheel's ground-contact point, causing excessive movement and instability under external disturbances.
Innovation Solution
A vehicle body frame structure featuring a main frame extending from the head pipe with a truss shape composed of upper and lower frames and reinforcing frames, where the front ends of the upper frames are fixed to the head pipe and the lower frames are connected to a single down-frame, providing a balance of rigidity and weight reduction by adjusting the diameter and placement of sub-frames and reinforcing frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rigidity of the vehicle body frame is increased by connecting front ends of upper and lower main pipes to the head pipe, then the structural strength is improved, but the weight increases and steering stability deteriorates
Solution Approach 1:
The vehicle body frame is segmented into multiple functional components: upper main pipes, lower main pipes, down-pipes, and reinforcing pipes. Each segment is strategically positioned and connected to achieve optimal strength-to-weight ratio. The down-pipe extends downward from the head pipe to create a lower mounting point, segmenting the vertical load path and enabling better weight distribution without excessive overall weight.
Solution Approach 2:
Different regions of the vehicle body frame are given different structural qualities. The down-pipe is specifically designed with appropriate thickness and diameter at critical locations to provide necessary strength for steering stability without adding unnecessary weight throughout the entire frame. The reinforcing pipes are strategically placed only where additional strength is needed, such as near the head pipe connections.
2Strength
If the rigidity of the vehicle body frame is increased by connecting front ends of upper and lower main pipes to the head pipe, then the structural strength is improved, but the steering stability deteriorates due to long distance from torsional center to ground-contact point
Solution Approach 1:
Instead of connecting the upper and lower main pipes directly to the head pipe at the top, the invention inverts the connection approach by introducing a down-pipe that extends downward from the head pipe. The lower main pipes connect to this downward-extending down-pipe, effectively inverting the conventional connection pattern to lower the torsional center and improve steering stability.
Solution Approach 2:
The down-pipe extends in the vertical dimension (downward direction) from the head pipe, creating a new spatial dimension for load distribution. This vertical extension allows the frame to better resist torsional forces by distributing loads through a longer vertical lever arm, thereby reducing the effective distance from the torsional center to the ground-contact point and improving steering stability.
3Stability of the object's composition
If multiple reinforcing pipes are added to connect upper and lower main pipes, then the structural rigidity is improved, but the device complexity increases
Solution Approach 1:
Multiple reinforcing pipes are merged into a unified structural system that works together with the upper and lower main pipes. The reinforcing pipes are strategically positioned to work in conjunction with the down-pipe and main pipes, creating a coordinated reinforcement pattern that maximizes rigidity while minimizing the number of separate components and connection points.
Data Source
AI summary
A vehicle body frame includes a main frame that extends from a head pipe toward the vehicle rear side above an engine and a down-frame that extends downward from one end fixed to the head pipe. The main frame is assembled into a truss shape from a pair of left and right upper frames and a pair of left and right lower frames and reinforcing frames disposed between these upper frames and lower frames. Front end parts of the upper frames are fixed to the upper end side of the head pipe and front end parts of the lower frames are fixed to a part close to the head pipe in the single down-frame.