Two-Shaft EV Powertrain With Planetary Gearing for Compact Multi-Speed Drive
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Solution Overview
Problem
Conventional powertrains for electric vehicles occupy a large space due to their three-shaft structure, limiting passenger compartment size and struggling to meet performance requirements for high-performance or large vehicles with a single speed reduction ratio.
Innovation Solution
A compact powertrain design using a two-shaft structure with a planetary gear set and differential, allowing power transmission through multiple paths and enabling selective connections via clutches and brakes for various gear stages, reducing space occupancy and enhancing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-shaft structure is used for power transmission, then power can be transmitted reliably, but the space occupied increases and passenger compartment size is limited
Solution Approach 1:
The patent merges the functions of multiple shafts into a two-shaft structure by integrating the planetary gear set and differential assembly. The planetary gear set combines sun gear, planet gears, and ring gear to achieve multiple gear ratios while the differential assembly handles power distribution to drive wheels, eliminating the need for a third shaft while maintaining reliable power transmission through coordinated operation of these integrated components.
Solution Approach 2:
The planetary gear set serves multiple functions within the two-shaft structure: it provides multiple gear reduction ratios (first, second, and third gear stages), enables direct connection between motor and differential, and facilitates reversible power flow. This multi-functionality allows the compact two-shaft design to replace the conventional three-shaft structure without sacrificing transmission reliability.
2Device complexity
If a single speed reduction ratio is used, then the structure is simple, but acceleration and maximum speed performance requirements cannot be met
Solution Approach 1:
The patent implements a dynamic transmission system with multiple gear stages (first, second, and third gear reduction ratios) that can be selectively engaged based on vehicle operating conditions. The control unit dynamically switches between different clutch and brake combinations to select appropriate gear ratios: using higher reduction ratios for acceleration and lower ratios for maximum speed, thereby meeting diverse performance requirements while maintaining a relatively simple two-shaft structure.
Solution Approach 2:
The system changes the speed reduction ratio parameter dynamically by selectively engaging different clutch and brake combinations. The first clutch, second clutch, first brake, and second brake can be combined in various ways to provide at least three different gear reduction ratios, allowing the transmission system to adapt to different driving conditions (acceleration, cruising, maximum speed) without fundamentally changing the two-shaft structural configuration.
3Productivity
If multiple gear stages are added to improve performance, then acceleration and maximum speed performance improve, but electricity consumption increases
Solution Approach 1:
The planetary gear set enables direct mechanical connection between the motor and differential through multiple gear stages, allowing the system to achieve optimal gear ratios without excessive electromagnetic torque demands. By providing mechanical advantage through gear reduction, the system reduces the electrical load on the motor during acceleration, thereby improving performance while controlling electricity consumption through efficient mechanical power transmission.
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 compact design improves mountability, allows for a larger passenger compartment, and achieves better acceleration and maximum speed performance while reducing electricity consumption.
Implementation Method 1
a planetary gear set connected to the first input shaft and mounted so as to allow power from the motor shaft to be supplied via a plurality of paths
Implementation Method 2
a first driven gear mounted to a differential and configured to mesh with the first driving gear, and a second driven gear mounted to the differential and configured to mesh with the second driving gear
Implementation Method 3
The carrier may be selectively connected to the motor shaft via a first clutch, the second input shaft may be selectively connected to the motor shaft via a second clutch, and the ring gear may be selectively secured to the case by a brake
Data Source
AI summary
A powertrain for a motorized vehicle includes a motor shaft connected to a motor, a first input shaft configured to be selectively connected to the motor shaft and provided with a first driving gear mounted on the first input shaft, a second input shaft configured to be selectively connected to the motor shaft and provided with a second driving gear mounted on the second input shaft, a planetary gear set connected to the first input shaft and mounted so as to allow power from the motor shaft to be supplied via a plurality of paths, a first driven gear mounted to a differential and configured to mesh with the first driving gear, and a second driven gear mounted to the differential and configured to mesh with the second driving gear.