Compact EV Transmission Nested Planetary Gearsets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric vehicle transmissions are often bulky and lack a compact design, with limited gear options, which can impact efficiency and space utilization in electric vehicle drivetrains.
Innovation Solution
A compact electric vehicle transmission design featuring two planetary gearsets with specific element connections and shifting elements allows for a solid connection between components, enabling a compact structure and efficient power flow with two gear options between the drive input and output shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional electric vehicle transmission with one or two gears is used, then the transmission can provide basic gear reduction, but the structure becomes bulky and space utilization is poor
Solution Approach 1:
The patent implements a nested planetary gear configuration where a first planetary gearset and a second planetary gearset are arranged concentrically, with the second planetary gearset positioned inside the first. This nesting allows multiple gear reduction stages to be compacted into a single transmission unit, providing multiple gear options (first gear, second gear, and third gear) without increasing the overall transmission volume, thereby resolving the contradiction between compact size and gear versatility.
Solution Approach 2:
The transmission is segmented into two independent planetary gearsets, each capable of providing gear reduction. The first planetary gearset provides a first gear ratio, the second planetary gearset provides a second gear ratio, and their combination provides a third gear ratio. This segmentation allows the transmission to achieve multiple gear options through selective engagement of different gearset combinations, maintaining compact size while increasing adaptability.
2Adaptability or versatility
If frictional shifting elements are used to enable gear changes, then gear options are provided, but continuous energy supply is required for operation
Solution Approach 1:
The patent employs locking elements (such as clutch brakes or dog clutches) that can lock the planetary gearsets into fixed gear ratios without requiring continuous energy supply. Once a gear is engaged, the locking element maintains the gear position mechanically, eliminating the need for continuous electrical power to frictional shifting elements. This self-service mechanism reduces energy consumption while maintaining gear shifting capability.
Solution Approach 2:
The shifting mechanism operates periodically rather than continuously. The locking elements are engaged and disengaged only when gear changes are required, rather than maintaining constant engagement. This periodic action reduces the average energy consumption of the shifting system compared to continuous operation of frictional shifting elements.
Data Source
AI summary
Disclosed is an electric vehicle transmission (6″) comprising a drive input shaft (11), a drive output shaft (13), a first planetary gearset (15), and a second planetary gearset (16). The drive input shaft (11) is provided for connection to an electric machine (7), where each of the first planetary gearset (15) and the second planetary gearset (16) includes a first element (17, 18), a second element (19, 20) and a third element (21, 22), respectively. A first shifting element (A) and a second shifting element (B′) are provided, by the selective actuation of which the drive input shaft (11) can be connected to the drive output shaft (13) by means of the planetary gearsets (15, 16) by engaging a gear. Also disclosed is a drive module (2″) with such an electric vehicle transmission (6″) and a method for operating an electric vehicle transmission (6″).