Three-Motor Planetary Powershift Transmission for Compact EV Drive Units
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric drive units for vehicles face challenges in achieving desired sizing constraints, particularly in terms of drop and width, due to the layout of clutches and gear reductions, which can lead to incompatibility with certain vehicle types, such as all-wheel drive loaders, and result in lower efficiency and torque-to-weight ratios compared to planetary transmissions.
Innovation Solution
A multi-speed transmission system incorporating three electric motors with a planetary gear set arranged between two clutches, where the first clutch couples to the carrier and the second clutch grounds the ring gear, allowing for compact packaging and efficient integration into various vehicle platforms, while minimizing power interruptions during shifting through the use of wet friction clutches and a dry sump system to reduce splash losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple gears are positioned on the output shaft to increase power output, then the drive unit's power capability is improved, but the transmission width increases which poses barriers to integration in certain vehicle platforms
Solution Approach 1:
The transmission is divided into multiple independent planetary gear sets (first planetary gear set, second planetary gear set, third planetary gear set) arranged in parallel rather than stacking gears on a single output shaft. Each planetary gear set handles a portion of the power transmission, allowing the transmission to achieve high power output while maintaining a compact width suitable for vehicle integration.
2Adaptability or versatility
If clutches and gear reductions are arranged on downstream shafts to achieve multiple gear ratios, then the transmission's gear ratio capability is improved, but the unit's width increases which may not meet packaging demands
Solution Approach 1:
Multiple planetary gear sets are merged into a single integrated transmission structure where the first, second, and third planetary gear sets share common components (input shaft, output shaft, housing). The clutches are integrated within the planetary gear set assembly rather than positioned on separate downstream shafts, reducing the overall width while maintaining multiple gear ratio capabilities through the coordinated operation of the planetary sets.
3Weight of moving object
If a planetary gear set is used to achieve gear reduction and compact design, then the torque-to-weight ratio and efficiency are improved, but the transmission may be incompatible with certain vehicle platforms requiring longer drops
Solution Approach 1:
The transmission design transitions from a single-stage planetary gear arrangement to a multi-stage configuration with three planetary gear sets arranged in series along the axial direction. This dimensional arrangement allows the transmission to achieve the required long drop (axial length) for certain vehicle platforms while maintaining the high torque-to-weight ratio and efficiency benefits of planetary gearing. The extended axial arrangement provides the necessary packaging flexibility for different vehicle applications.
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 enables efficient integration into vehicles with stringent packaging demands, providing sufficient tractive effort and top speed, while enhancing transmission performance and reducing power interruptions during shifting, thus improving customer appeal and operational efficiency.
Implementation Method 1
a planetary gear set arranged between a first clutch and a second clutch where the first clutch is coupled to a carrier of the planetary gear set via a gear and the second clutch grounds a ring gear of the planetary gear set
Implementation Method 2
the use of wet friction clutches and a dry sump system to reduce splash losses
Data Source
AI summary
Systems and methods for an electric drive unit are provided. A transmission system in an electric drive unit includes first, second, and third input shafts rotationally coupled to first, second, and third electric machines, respectively, wherein the first and third electric machines are arranged on a first side of the transmission and the second electric machine is arranged on a second opposing side of the transmission. The transmission system further includes an idler shaft that connects the first, second, and third electric machines and couples to a sun gear of a planetary gear set. The planetary gear set is arranged between a first and second clutch wherein the first clutch couples to a carrier and the second clutch couples to a ring gear. An output shaft is spaced away from the planetary gear set via gear and includes two flanges to couple the transmission to outputs.