Straddled Vehicle Transmission Gear Ratio Control for Battery-Independent Acceleration
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Solution Overview
Problem
Straddled vehicles with electrically-driven transmission systems face reduced acceleration responsiveness due to battery charge state, as motor power output decreases with lower battery power, affecting the vehicle's ability to maintain consistent acceleration performance.
Innovation Solution
A control device adjusts the transmission gear ratio of the electrically-driven transmission system based on battery charge levels before accelerating, increasing engine and motor power output to maintain target power levels regardless of battery charge, by changing the gear ratio to prioritize power margin and reduce inertia torque loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If motor power is used to assist engine running, then acceleration responsiveness is improved, but motor power output decreases with lower battery charge state
Solution Approach 1:
The control device performs preliminary action by changing the transmission gear ratio before accelerating manipulation when battery power is low. This anticipatory adjustment ensures the engine operates at optimal rotation speed during acceleration, compensating for the reduced motor power availability and maintaining consistent acceleration responsiveness regardless of battery charge state.
Solution Approach 2:
The invention applies parameter changes by dynamically adjusting the transmission gear ratio based on battery power levels. When battery power is insufficient, the control device modifies the gear ratio to optimize engine rotation speed, thereby maintaining the target crankshaft power output despite reduced motor assistance capability.
2Power
If transmission gear ratio is changed during acceleration, then target power can be achieved, but lag time increases due to gear shifting and inertia torque loss
Solution Approach 1:
The control device performs preliminary action by pre-adjusting the transmission gear ratio before the rider initiates acceleration. This ensures the transmission is already in the optimal gear position when acceleration begins, eliminating the need for mid-acceleration gear shifts and reducing the lag time caused by inertia torque loss during gear changes.
Solution Approach 2:
The invention applies dynamics by making the transmission gear ratio adjustable and responsive to battery power levels. The control device dynamically selects the appropriate gear ratio based on real-time battery power assessment, enabling smooth and continuous power delivery without the interruptions and time losses associated with traditional fixed-ratio or delayed-shift transmissions.
3Power
If throttle valve opening is increased to achieve target power, then engine power increases, but responsiveness is reduced compared to direct power addition
Solution Approach 1:
The invention applies parameter changes by adjusting the transmission gear ratio rather than relying solely on increasing throttle valve opening. This alternative parameter adjustment allows the engine to deliver target power more rapidly by optimizing the rotational speed transmission to the drive wheel, achieving faster power response compared to merely opening the throttle further.
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 approach ensures reproducible and high acceleration responsiveness to rider input, maintaining consistent power output even with low battery charge, reducing lag time and improving cornering performance.
Implementation Method 1
a generator motor configured to operate in cohesion with the crankshaft, generate electric power by being driven by the engine
Implementation Method 2
a battery configured to store the electric power generated by the generator motor when the generator motor is driven by the engine and supply the generator motor with the electric power stored therein
Data Source
Figure 1(a)~1(c)
Figure 2
Figure 3
AI summary
The present teaching provides a straddled vehicle having reproducible vehicle acceleration responsiveness to accelerating manipulation regardless of a charge state of a battery. The straddled vehicle includes a control device that increases a power margin by changing, prior to accelerating manipulation, a transmission gear ratio of an electrically-driven transmission device depending at least on an amount of decrease from a full-charge capacity of the battery storing electric power so that power being outputted from a crankshaft by a generator motor driven by the electric power stored in the battery and/or an engine increases, in response to the accelerating manipulation, to a target power according to the accelerating manipulation regardless of an amount of charge remaining in the battery. The power margin is a difference between a power outputted by the engine at a point in time prior to the accelerating manipulation and a maximum power producible by the engine at a rotation speed at the point in time prior to the accelerating manipulation.