BEV Manual-Shift Control With Low-Speed Gear for High Driving Force
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Solution Overview
Problem
Battery electric vehicles (BEVs) with electric motors as a driving source often face reduced drivability due to insufficient driving force in situations requiring a large driving force, limiting their performance in scenarios like steep uphill driving or off-road conditions.
Innovation Solution
The implementation of a battery electric vehicle configuration that includes an electric motor, a driving operation member, a pseudo shifting operation member, a transmission with the ability to manually switch between gear ratios, and a control device. This setup allows drivers to simulate manual shifting operations, enabling the vehicle to generate a larger driving force by switching to a low-speed gear ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a virtual manual transmission is implemented in a battery electric vehicle, then the driving experience of operating a manual transmission vehicle is improved, but the driving force becomes insufficient in situations requiring large driving force
Solution Approach 1:
The transmission system is segmented into two independent components: a virtual manual transmission for control experience and a physical low-speed gear for mechanical force multiplication. The virtual transmission (first transmission) provides shift positions and virtual gear ratios for operational experience, while the low-speed gear (second transmission) provides additional mechanical advantage. This segmentation allows each component to fulfill its specific function without compromise.
Solution Approach 2:
The patent merges the virtual transmission system and the physical low-speed gear into a unified transmission control system. The control device integrates signals from both the virtual shift positions and the low-speed gear selection to determine the final motor torque output. This merging allows the system to simultaneously provide manual shifting experience and enhanced driving force by combining the effects of virtual gear ratios and mechanical gear reduction.
2Device complexity
If the driving force is limited by the maximum torque of the electric motor and the reduction ratio, then the system simplicity is maintained, but the drivability decreases in situations requiring large driving force
Solution Approach 1:
The transmission system is made dynamic by allowing the driver to manually select between different low-speed gear ratios based on driving conditions. The control device dynamically adjusts the motor torque by combining the virtual gear ratio from the first transmission with the selected low-speed gear ratio from the second transmission. This dynamic adaptability enables the system to optimize driving force output for different situations such as steep uphill driving or off-road conditions.
Data Source
AI summary
A battery electric vehicle includes: an electric motor configured to serve as a driving source for the battery electric vehicle; a driving operation member configured to be used to drive the battery electric vehicle; a pseudo shifting operation member that imitates an operation member configured to be used to perform a shifting operation of a manual transmission internal combustion engine vehicle; a transmission mounted between the electric motor and a drive wheel and configured to allow a driver to manually switch between a gear ratio for normal use and a low-speed gear ratio; and a control device configured to control a motion of the battery electric vehicle in response to an operation of the driving operation member according to an operation state of the pseudo shifting operation member and a gear ratio selected by the transmission.