Articulated Rear Arm Control for Rear-Wheel Grip in Straddled Vehicles
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Solution Overview
Problem
Existing straddled vehicles face challenges in adjusting the gripping force of the rear wheel, which is influenced by the coefficient of friction between the road surface and the rear wheel, and the rear wheel vertical load, making it difficult to optimize traction during various driving conditions.
Innovation Solution
A straddled vehicle design featuring a rear arm connected to the vehicle body frame via a pivot shaft, with a first arm and a second arm supported by a rotary shaft, and an actuator to control the bending angle of the rear arm, allowing for adjustment of the gripping force through a power control device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the coefficient of friction between the road surface and the rear wheel is increased to improve gripping force, then the gripping force is improved, but it is not easy to increase these as they are affected by specifications of the rear wheel or road surface conditions
Solution Approach 1:
The invention changes the parameter of rear wheel vertical load dynamically by using an actuator to adjust the rear arm angle. This allows the gripping force to be adjusted by changing the load distribution rather than relying on fixed friction coefficients, enabling adaptation to different road conditions and driving states.
Solution Approach 2:
The invention introduces a dynamic adjustment mechanism where the rear arm angle can be actively controlled by an actuator based on detected driving states (acceleration, deceleration, turning). This transforms the static gripping force into a dynamically adjustable parameter that adapts to varying road conditions and driving requirements.
2Force
If the rear wheel vertical load is increased to improve gripping force, then the gripping force is improved, but it is undesirable to increase the loads of the straddled vehicle and the driver
Solution Approach 1:
The invention changes the distribution of vertical load on the rear wheel by adjusting the rear arm angle via an actuator. This allows the gripping force to be enhanced through load redistribution rather than increasing the overall vehicle weight, maintaining a comfortable and safe riding experience while improving traction.
3Ease of operation
If the chain force factor is made constant to simplify control, then the control is simplified, but the angle of the rear arm constantly changes in response to the throttle operation causing the chain force factor to constantly vary
Solution Approach 1:
The invention uses a feedback control mechanism where the actuator is controlled based on the detected driving state (acceleration, deceleration, turning). The power control device adjusts the rear arm angle to maintain appropriate gripping force by responding to real-time driving conditions, ensuring both control simplicity and gripping force consistency.
Solution Approach 2:
The invention dynamically adjusts the rear arm angle based on detected driving states to maintain optimal gripping force. Rather than attempting to keep the chain force factor constant through rigid control, the system adaptively modifies the rear arm configuration to compensate for variations in throttle operation and maintain reliable traction.
4Device complexity
If a simple rear arm structure is used to reduce device complexity, then the device complexity is reduced, but there remains improvement in terms of adjusting a gripping force of the rear wheel
Solution Approach 1:
The invention adds a rotary shaft to the rear arm structure, enabling the second arm to rotate relative to the first arm. This dynamic configuration allows the gripping force to be adjusted by changing the rear arm angle through an actuator, providing adaptability without significantly complicating the overall structure.
Solution Approach 2:
The rear arm is divided into a first arm and a second arm connected by a rotary shaft. This segmentation allows independent rotation of the second arm relative to the first arm, enabling gripping force adjustment while maintaining a relatively simple and modular structure that is easy to manufacture and maintain.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A straddled vehicle (1) includes a vehicle body frame (2), a pivot shaft (P), and a rear arm (9). The pivot shaft (P) is supported by the vehicle body frame (2). The rear arm (9) is connected to the vehicle body frame (2) via the pivot shaft (P). The rear arm (9) rotates around the pivot shaft (P) relative to the vehicle body frame (2). The rear arm (9) supports a rear wheel (11) via a rear axle (R). The rear arm (9) includes at least a first arm (9A), a rotary shaft (M), and a second arm (9B). The first arm (9A) is connected to the vehicle body frame (2). The first arm (9A) rotates around the pivot shaft (P) relative to the vehicle body frame (2). The rotary shaft (M) is provided at a rear end portion of the first arm (9A). The second arm (9B) is connected to the first arm (9A) via the rotary shaft (M). The second arm (9B) rotates around the rotary shaft (M) relative to the first arm (9A). The second arm (9B) supports the rear wheel (11) via the rear axle (R).