Dual-Motor EV Drivetrain With Planetary Reduction and Torque Split
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Solution Overview
Problem
Existing driving apparatuses for electric vehicles face challenges in achieving high efficiency, low cost, and compact design, particularly when using rare earth element permanent magnets, leading to issues like no-load drag, increased investment cost, and reduced travel distance and fuel efficiency, especially in four-wheel drive vehicles.
Innovation Solution
A driving apparatus combining two motors and three reduction mechanisms, including a first and second motor with different types or specifications, and first, second, and third reduction mechanisms, with a disconnector, transmission mechanism, and limited slip differential, to optimize torque and efficiency across various driving conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a motor system with rare earth element permanent magnets is used to achieve high efficiency and high torque, then torque and output performance are improved, but investment cost increases and efficiency gain decreases relative to cost when exceeding certain limits
Solution Approach 1:
The driving apparatus is divided into two separate motors (first motor and second motor) with different functions and characteristics. The first motor handles high-torque requirements while the second motor handles auxiliary functions, allowing each motor to be optimized independently for cost and performance rather than requiring one oversized expensive motor
Solution Approach 2:
The system uses two motors with different specifications and characteristics rather than a single motor. This allows parameter optimization where each motor is sized and specified appropriately for its specific function, reducing overall system cost while maintaining required performance
2Power
If a motor system with rare earth element permanent magnets is used to meet torque requirements, then torque output is improved, but device complexity and cooling capacity requirements increase
Solution Approach 1:
The driving apparatus is divided into two separate motors (first motor and second motor) with different functions and characteristics. The first motor handles high-torque requirements while the second motor handles auxiliary functions, allowing each motor to be optimized independently for cost and performance rather than requiring one oversized expensive motor
Solution Approach 2:
The second motor is designed with lower efficiency characteristics and lower cost, accepting that it will consume more energy and require more cooling, but this is acceptable for auxiliary functions where maximum efficiency is not critical, thus reducing overall system complexity and cost
3Power
If an auxiliary driving source with the same torque and output specifications as a motor system with non-rare earth element motor is used, then torque and output performance are improved, but size, volume, and cooling capacity cannot be avoided compared to rare earth element permanent magnet driving apparatus
Solution Approach 1:
The driving apparatus is divided into two separate motors (first motor and second motor) with different functions and characteristics. The first motor handles high-torque requirements while the second motor handles auxiliary functions, allowing each motor to be optimized independently for cost and performance rather than requiring one oversized expensive motor
Solution Approach 2:
The second motor is designed with lower efficiency characteristics and lower cost, accepting that it will consume more energy and require more cooling, but this is acceptable for auxiliary functions where maximum efficiency is not critical, thus reducing overall system complexity and cost
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 solution enhances driving torque, improves acceleration performance, and increases fuel efficiency by adapting to different driving regions, maintaining efficiency gain and cost-effectiveness even with changing performance specifications.
Implementation Method 1
a first reduction mechanism including a first planetary gear set disposed on one driveshaft, including first, second, and third rotation elements, and reducing the rotation speed of the torque input from the first motor and outputting to a differential ring gear of the differential
Implementation Method 2
a second reduction mechanism including a second planetary gear set disposed between the second motor shaft and the output shaft, which includes fourth, fifth and sixth rotation elements, and reduces speed of torque input from the second motor and outputs to the output shaft
Implementation Method 3
a differential mechanism disposed on the other driveshaft, and transmitting the driving torque to the wheels through both driveshafts
Data Source
AI summary
A driving apparatus for an electric vehicle includes a first motor transmits driving torque to the wheels on both sides, and including a first motor shaft of a hollow shaft, a second motor disposed parallel to the first motor, an output shaft coaxially disposed with a second motor shaft of the second motor, a first reduction mechanism including a first planetary gear set disposed on one driveshaft, including first, second, and third rotation elements, a second reduction mechanism including a second planetary gear set disposed between the second motor shaft and the output shaft, which includes fourth, fifth and sixth rotation elements, and reduces speed of torque input from the second motor and outputs to the output shaft, and a third reduction mechanism including an output gear fixed to one side of the output shaft and the differential ring gear engaged with the output gear.