Two-Speed Gearbox Gear Intervention for Rear Motor Range Control
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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 within the optimal working range, particularly in four-wheel drive mode, leading to unmet power requirements for drivers.
Innovation Solution
A method and system for controlling the gear of a two-speed gearbox that determines a target gear based on current vehicle speed, position information of the drive gear-lever, rotation-speed of the drive motor, and gear fault information, shifting gears to match real-time operation conditions, thereby ensuring optimal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-speed bridge gearbox is used, then the structure is simple and reliable, but the motor cannot operate in optimal working range under varying driving conditions, failing to meet power requirements
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed single-speed gearbox to a two-speed gearbox with variable speed ratios. The gearbox can dynamically switch between first speed ratio (lower gear) and second speed ratio (higher gear) based on real-time driving conditions, allowing the motor to operate within optimal working range across different vehicle speeds and load conditions.
Solution Approach 2:
The patent implements parameter changes by modifying the speed ratio parameter of the gearbox. The two-speed gearbox provides two distinct speed ratio parameters (first speed ratio and second speed ratio), enabling the system to adapt motor operating parameters to match varying driving demands, thereby improving both reliability and adaptability.
2Device complexity
If conventional control strategies are used for two-speed gearbox, then the control logic is simple, but the rear axle drive motor cannot be ensured to be in optimal working range
Solution Approach 1:
The patent applies feedback by implementing a control strategy that continuously monitors motor rotation speed and compares it with optimal working range parameters. Based on this feedback, the control system automatically adjusts gearbox gear selection to maintain motor operation within optimal range, thereby improving motor efficiency without excessive complexity.
Solution Approach 2:
The patent uses preliminary action by pre-establishing optimal working range parameters for the motor and pre-defining control rules for gear switching. This allows the control system to proactively adjust gear selection before the motor deviates from optimal range, maintaining high efficiency without requiring complex real-time calculations.
3Productivity
If frequent gear shifting is performed to maintain optimal motor operation, then motor working range is optimized, but gear wear and NVH issues increase
Solution Approach 1:
The patent applies partial action by implementing gear shifting only when necessary to maintain motor operation within optimal working range. The control strategy uses threshold-based decision making, shifting gears partially (only when conditions warrant) rather than continuously, thereby reducing gear wear and NVH while still optimizing motor efficiency.
Solution Approach 2:
The patent uses beforehand cushioning by incorporating buffer zones and hysteresis in gear shifting logic. The control system anticipates potential excessive shifting by setting threshold margins, cushioning against unnecessary gear changes that would increase wear and NVH while still maintaining motor efficiency within acceptable ranges.
Data Source
AI summary
A method and a system for controlling a gear of the two-speed gearbox and a vehicle is provided. 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.