Two-Speed Gearbox Shift Control for Rear Motor Speed Matching
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Solution Overview
Problem
Conventional control strategies for two-speed gearboxes in electric or hybrid vehicles fail to ensure the rear axle drive motor operates in the optimal working range, unable to meet the power demands of users, particularly in four-wheel drive modes.
Innovation Solution
A method and system for controlling the gear of a two-speed gearbox, which determines a target gear based on current vehicle speed and performs gear intervention control using position information of the drive gear-lever, rotation-speed of the drive motor, and gear fault information to shift gears and maintain optimal operation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-speed bridge gearbox is used, then the structure is simple, but the motor cannot operate in optimal working range under different driving conditions
Solution Approach 1:
The patent implements a two-speed gearbox with variable transmission ratios that can dynamically adapt to different driving conditions. The system switches between first and second transmission ratios based on motor rotation speed and driving mode, allowing the motor to operate within optimal working range across varying vehicle speeds and torque requirements.
Solution Approach 2:
The patent changes the transmission ratio parameter by providing two different ratios (first transmission ratio and second transmission ratio) in the gearbox. This allows the system to adjust the relationship between motor speed and vehicle speed, ensuring the motor operates in optimal ranges under different driving conditions while maintaining structural simplicity.
2Device complexity
If conventional control strategies are used, then the control system is simple, but the rear axle drive motor cannot be ensured to be in optimal working range
Solution Approach 1:
The control system continuously monitors motor rotation speed and compares it with predetermined thresholds. Based on this feedback, the controller automatically selects appropriate transmission ratios and determines gear shift timing, ensuring the motor operates within optimal working range without requiring complex manual intervention or overly complicated control algorithms.
3Reliability
If frequent gear shifts are performed, then the motor can maintain optimal working range, but the gearbox service life is reduced
Solution Approach 1:
The control system performs gear shifts only when necessary, based on comparisons between motor rotation speed and predetermined thresholds. This partial action approach ensures the motor remains in optimal working range while avoiding unnecessary frequent shifts that would reduce gearbox service life, achieving a balanced operation strategy.
4Device complexity
If gear intervention control is not performed, then the control system is simple, but the vehicle cannot meet power demands in four-wheel drive mode
Solution Approach 1:
The system dynamically adjusts transmission ratios based on driving mode (two-wheel drive or four-wheel drive) and motor rotation speed. In four-wheel drive mode, the control system selects appropriate gear ratios to ensure sufficient power delivery while maintaining motor operation within optimal working range, thereby meeting high power demands without requiring overly complex control strategies.
Data Source
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AI summary
A method and a system for controlling a gear of the two-speed gearbox and a vehicle. The method for controlling a gear of a two-speed gearbox includes: determining a first target gear of the gearbox reflecting a current driving demand of a user according to a current vehicle-speed; and performing a gear intervention control of the gearbox based on at least one of the following aspects: position information of a drive gear-lever, a rotation-speed of a drive motor of a vehicle, and gear fault information of the gearbox, to shift the first target gear of the gearbox to a second target gear of the gearbox that matches with real-time operation conditions of the vehicle. In the present application, the method and system for controlling the gear of the two-speed gearbox and the vehicle ensure that the drive motor is in the optimal working range and meets the current needs of users.