Two-Speed Transmission for Electric Vehicle Torque Optimization
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Solution Overview
Problem
Existing one-speed transmissions in electric vehicles are limited by constant gear ratios, resulting in poor climbing capability, high energy consumption during start-up, and inefficient energy utilization, as they cannot provide sufficient torque when driving uphill or high speed when driving on flat roads.
Innovation Solution
A two-speed transmission system with two planet gear assemblies and clutches, allowing for switching between high and low gear ratios to optimize torque and speed output based on driving conditions, utilizing a first and second transmission mechanism with distinct gear ratios and clutches to connect and disconnect with the spindle for different torque outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a one-speed transmission with constant gear ratio is used, then the transmission structure is simple, but the climbing capability is poor and torque is insufficient when driving uphill
Solution Approach 1:
The transmission system is segmented into two distinct transmission mechanisms (first and second transmission mechanisms), each with different gear ratios. This allows the system to provide different torque levels for different driving conditions, resolving the contradiction between simple structure and sufficient torque by dividing the transmission function into multiple specialized subsystems.
Solution Approach 2:
The transmission system transitions from a static constant gear ratio to a dynamic variable gear ratio system. The controller dynamically switches between first and second gear ratios based on driving conditions (uphill, flat road, acceleration), enabling the transmission to adapt torque output to real-time requirements, thus improving climbing capability without permanently increasing structural complexity.
2Speed
If a one-speed transmission with constant gear ratio is used, then the transmission structure is simple, but the speed is limited when driving on flat roads
Solution Approach 1:
The transmission system is divided into two distinct transmission mechanisms with different gear ratios optimized for different speed requirements. The first transmission mechanism provides higher speed for flat road driving, while the second provides lower speed with higher torque for uphill conditions, resolving the speed limitation without requiring a complex multi-speed transmission.
Solution Approach 2:
The system changes the transmission gear ratio parameter based on driving conditions. By switching between first gear ratio (higher speed) and second gear ratio (lower speed, higher torque), the system optimizes vehicle speed for different road conditions, effectively resolving the contradiction between simple structure and speed performance.
3Use of energy by moving object
If a one-speed transmission is used, then the transmission structure is simple, but energy utilization rate is low and start-up is energy consuming
Solution Approach 1:
The transmission system dynamically adjusts gear ratio based on driving conditions to optimize energy utilization. During start-up and acceleration, the system selects appropriate gear ratios to maximize torque output and minimize energy consumption, resolving the contradiction between simple structure and energy efficiency by introducing dynamic adaptation.
Solution Approach 2:
The transmission gear ratio parameter is changed based on driving conditions to optimize energy utilization. The controller monitors driving state and switches between gear ratios to ensure optimal energy transfer from motor to wheels, improving energy utilization rate without requiring a completely complex transmission structure.
4Reliability
If a one-speed transmission with constant gear ratio is used, then the transmission structure is simple, but the electric motor may be dragged or burnt down when driving down the slope with accelerated speed
Solution Approach 1:
The transmission system provides dynamic gear ratio adjustment to protect the motor during downhill driving. When the vehicle accelerates downhill, the controller can switch to appropriate gear ratios to prevent motor dragging and potential burnout, enhancing reliability without requiring a completely complex transmission structure.
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
The two-speed transmission enhances climbing capability and energy utilization by providing higher torque for uphill driving and higher speed for flat roads, improving driving efficiency and reducing the risk of motor drag or burnout.
Implementation Method 1
The first planet gear is furnished on the first planet bracket and meshed between the first ring gear and the first sun gear. The second planet gear is furnished on the second planet bracket and meshed between the second ring gear and the second sun gear.
Data Source
AI summary
A two-speed transmission for an electric vehicle including an electric motor, a first transmission mechanism and a second transmission mechanism is provided. The electric motor includes a rotor and a spindle. The rotor drives a first sun gear and a first planet gear of the first transmission mechanism to rotate with respect to the first ring gear to generate a first gear ratio. The rotor drives a second sun gear and a second planet gear of the second transmission mechanism to rotate with respect to the second ring gear to generate a second gear ratio different from the first gear ratio. When the first clutch connects with the spindle, the second clutch separates from the spindle, and a first torque is outputted to the spindle. When the second clutch connects with the spindle, the first clutch separates from the spindle, and a second torque is outputted to the spindle.