Two-Axis Electric Drive With Planetary Gear Disconnect
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Solution Overview
Problem
Current electric motor drive systems in vehicles face inefficiencies due to mechanical losses and environmental pollution, with a need for a more compact and lightweight design to enhance energy efficiency.
Innovation Solution
A two-axis electric drive system incorporating a planetary gear assembly with a sun gear, planetary gears, a ring gear, a brake, and a transfer gear mechanism, which allows for a high motor-to-axle ratio without a third axis, enabling a compact and reduced-weight design while maintaining the ability to disconnect during high-speed driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a traditional electric motor drive system is used, then the vehicle can be powered electrically, but the system occupies large space and has increased weight
Solution Approach 1:
The patent combines the electric motor, planetary gear assembly, and differential into a single integrated drive unit. The motor rotor is directly coupled to the sun gear, and the differential is integrated within the same housing, eliminating the need for separate mounting structures and reducing overall system weight while maintaining electrical propulsion functionality
Solution Approach 2:
The planetary gear assembly serves multiple functions simultaneously: it provides gear reduction for torque multiplication, enables the disconnect brake mechanism for high-speed efficiency, and integrates with the differential for power distribution. This multi-functionality reduces the need for separate components, thereby reducing weight while maintaining energy efficiency
2Use of energy by moving object
If a traditional electric motor drive system is used, then the vehicle can be powered electrically, but the system has large packaging requirements that influence vehicle design
Solution Approach 1:
The differential is nested within the planetary gear assembly housing, and the entire drive unit is compactly arranged with the motor rotor nested within the stator assembly. This nested configuration maximizes space utilization and minimizes the overall volume of the drive system while maintaining all necessary functional components for efficient electrical propulsion
Solution Approach 2:
By merging the motor, gear assembly, and differential into a single integrated unit with shared housing and mounting structures, the patent eliminates redundant spaces and reduces the total volume required for the drive system, thereby satisfying packaging requirements without compromising energy efficiency
3Power
If a high gear ratio is achieved through traditional means, then torque transmission is improved, but the system complexity increases with additional axes
Solution Approach 1:
The patent employs a selectable disconnect mechanism that dynamically changes the gear ratio based on operating conditions. At high speeds, the disconnect brake engages to create a direct drive path, bypassing the planetary reduction and eliminating the need for complex multi-axis gear trains. This dynamic adaptation provides high torque when needed while maintaining simplicity at high speeds
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 system achieves a compact and lightweight design with improved energy efficiency by utilizing a planetary gear assembly and transfer gear mechanism, allowing for a high gear ratio and efficient torque transmission to the drive wheels, while maintaining the simplicity of a ring brake disconnect.
Implementation Method 1
A planetary gear assembly includes a sun gear drivingly connected to the rotor, a plurality of planetary gears in meshing engagement with the sun gear
Implementation Method 2
A brake is connected to the ring gear
Data Source
AI summary
An electric drive for a vehicle includes an electric motor and a planetary gear assembly including a sun gear drivingly connected to a rotor of the electric motor. A ring gear of the planetary gear assembly is connected to a brake that can be released to provide the system with a disconnect. A first transfer gear is connected to the planetary carrier. A second transfer gear is drivingly engaged with the first transfer gear and rotatable about a second axis offset from an axis of the electric motor. A differential is drivingly connected to the second transfer gear and provides drive torque to a pair of drive shafts along the second axis.