BEV Pseudo Shifting With Multi-Gear Torque-Speed Control
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Solution Overview
Problem
Battery electric vehicles with electric motors as a driving source face limitations in providing sufficient driving force when high torque is required, and increasing the reduction ratio to address this can restrict high-speed travel.
Innovation Solution
A battery electric vehicle with a transmission having multiple switchable gear ratios and a pseudo shifter allowing selection of more shift positions, combined with a control device to manage motor torque and gear ratios based on accelerator operation, vehicle speed, and shift position, enabling pseudo shifting across a wide range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the reduction ratio is increased to provide sufficient driving force, then the driving force is improved, but the vehicle speed is limited due to motor rotational speed constraints
Solution Approach 1:
The patent segments the single reduction ratio into multiple gear ratios through a transmission system with multiple stages. Instead of using one large reduction ratio that limits speed, the transmission divides the reduction into several smaller steps (first stage, second stage, third stage gear ratios), allowing the vehicle to achieve both high driving force at low speeds and maintain high speed capability at higher velocities by switching between different gear stages.
2Adaptability or versatility
If a transmission with multiple gear ratios is introduced, then the vehicle can operate in a wider speed range, but the device complexity increases
Solution Approach 1:
The transmission system is designed to perform multiple functions across different operating conditions. The same transmission structure with multiple gear ratios serves both to provide high driving force at low speeds and to enable high-speed travel, eliminating the need for separate mechanisms for different speed ranges. The control device universally manages all gear stage transitions based on vehicle conditions.
3Ease of operation
If the number of pseudo shift positions is increased to match manual transmission operations, then the driving experience is improved, but the control complexity increases
Solution Approach 1:
The patent creates a virtual copy of manual transmission shifting operations through the pseudo shifter. Instead of implementing a complex mechanical manual transmission, the system replicates the shifting experience electronically by mapping pseudo shift positions to appropriate gear ratios and motor torque combinations. The control device copies the functional behavior of manual transmission shifts to provide familiar driving experience.
Data Source
AI summary
Vehicles according to embodiments of the present disclosure are battery electric vehicle having an electric motor as a driving source. The vehicle includes a transmission having a plurality of switchable gear ratios and a pseudo shifter capable of selecting a number of shift positions greater than the number of switchable gear ratios. The control device of the vehicle determines the combination of the motor torque of the electric motor and the gear ratio of the transmission so that the relationship between the accelerator operation amount, the vehicle speed, and the drive wheel torque is switched in accordance with the shift position selected by the pseudo shifter.