Electric Vehicle Transmission Using Nested Planetary Gearsets
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Solution Overview
Problem
Existing electric vehicle transmissions lack a compact design that allows for multiple gear ratios, making them less efficient and more complex in structure.
Innovation Solution
A compact electric vehicle transmission system utilizing three planetary gearsets with specific shifting elements to achieve multiple gear ratios between the drive input and output shafts, ensuring a fixed rotation speed ratio with the electric machine and enabling sequential gear engagement through shifting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple planetary gearsets are used to achieve various gear ratios, then the gear ratio versatility is improved, but the device complexity increases
Solution Approach 1:
The patent implements a nested arrangement where three planetary gearsets (first, second, and third) are concentrically positioned around a common central axis. The first planetary gearset is nested within the second, which is nested within the third, allowing all gearsets to share common structural elements such as the central axis and housing, thereby achieving multiple gear ratios without proportionally increasing overall complexity
Solution Approach 2:
The patent employs four shifting elements that can selectively engage different combinations of planetary gear elements (sun gears, planetary gears, ring gears) across all three planetary gearsets. This multi-functional shifting mechanism allows a single set of shifting elements to control multiple gear ratios and provide additional functions such as parking lock, reducing the need for separate mechanisms for each gear ratio
2Volume of moving object
If three planetary gearsets are used to achieve compact design, then the volume is reduced, but the device complexity increases
Solution Approach 1:
The three planetary gearsets are arranged concentrically with a common central axis, with each subsequent planetary gearset nested outward from the previous one. This nested configuration allows all three gearsets to occupy a compact radial space around the central axis, significantly reducing the overall transmission volume compared to a linear or distributed arrangement
Solution Approach 2:
The patent merges multiple functional elements into shared structural components. All three planetary gearsets share a common central axis and housing structure. The shifting elements are positioned to simultaneously control multiple planetary gearsets, and the ring gear of each planetary gearset is integrated with the structure of adjacent gearsets, consolidating what would otherwise be separate volume-consuming components
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 allows for a compact, efficient power flow with various gear ratios, reducing complexity and drag losses, and enabling a parking lock function, improving the overall efficiency and structure of the electric vehicle transmission.
Implementation Method 1
The first planetary gearset, the second planetary gearset and the third planetary gearset comprise in each case a first element, a second element, and a third element in the form, respectively, of a sun gear, a planetary web, and a ring gear
Data Source
AI summary
An electric vehicle transmission (7) has a drive input shaft (10), a drive output shaft (11), a first planetary gearset (P1), a second planetary gearset (P2), and a third planetary gearset (P3). The drive input shaft (10) is designed to be coupled to an electric machine (6). In addition, at least functionally a first shifting element (A), a second shifting element (B), a third shifting element (C), and a fourth shifting element (D) are provided. Also disclosed is a drive system (4), a vehicle drive-train (5), and an electric vehicle incorporating an electric vehicle transmission of this type.