E-Axle Planetary Transmission Layout for Wide Gear Ratios
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid drives with both an internal combustion engine and electric motor have complex configurations, leading to increased production costs and complexity, and often result in a loss of variability.
Innovation Solution
A cost-effective electric transmission for a motor vehicle drive train incorporating a reduction gear, planetary gear sets, and shift elements to create a compact, efficient, and lightweight transmission with multiple gear steps, including a differential, allowing for a high overall gear ratio and efficient power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both internal combustion engine and electric motor transmit power through a single transmission, then hybrid drive functionality is achieved, but device complexity and production costs increase
Solution Approach 1:
The patent combines the power transmission paths of both the internal combustion engine and electric motor through a unified transmission system. The transmission integrates multiple planetary gear sets that receive input from both drive sources and distribute power to output shafts, merging previously separate transmission paths into a single coordinated system that achieves hybrid functionality without requiring completely separate transmission chains.
Solution Approach 2:
The transmission system is designed as a universal platform that handles power from both the internal combustion engine and electric motor. The planetary gear sets and shift elements are configured to accommodate variable input sources, allowing the same transmission infrastructure to perform multiple functions: pure electric drive, pure combustion drive, and combined hybrid operation, thereby reducing overall system complexity.
2Device complexity
If transmission complexity is reduced, then production costs decrease, but drive variability and functionality are lost
Solution Approach 1:
The transmission is segmented into modular planetary gear sets (first and second planetary gear sets) with distinct functions. Each planetary gear set can operate independently or in combination, allowing the system to provide multiple gear steps and drive modes. This segmentation enables reduced complexity at the component level while maintaining high variability at the system level through selective engagement of different gear sets.
Solution Approach 2:
The transmission employs dynamic shift elements (clutches and brakes) that can selectively engage or disengage different planetary gear sets and connection paths. This dynamic reconfiguration capability allows the transmission to adapt its complexity level based on operating conditions, providing full hybrid functionality when needed while enabling simplified operation modes when appropriate, thus maintaining variability without permanent complexity.
3Adaptability or versatility
If multiple planetary gear sets are used to achieve high gear ratio, then gear step variability increases, but transmission size and weight increase
Solution Approach 1:
The patent implements nested planetary gear sets where the second planetary gear set is positioned within or adjacent to the first planetary gear set, sharing common structural elements such as housings, mounting points, and lubrication systems. This nesting arrangement allows multiple gear reduction stages to be achieved in a compact footprint, providing high overall gear ratios and multiple gear steps without proportionally increasing transmission volume.
Solution Approach 2:
The transmission merges the functional output of multiple planetary gear sets through a unified output mechanism. Both planetary gear sets contribute to the same output shaft or differential assembly, combining their gear multiplication effects to achieve high overall gear ratios. This merging approach avoids the need for separate transmission units for each gear set, reducing overall volume while maintaining gear step variability.
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 a compact, efficient, and cost-effective transmission that supports a wide range of gear ratios, reduces fuel consumption, and enhances ride comfort while maintaining power and reducing emissions.
Implementation Method 1
a first planetary gear set and a second planetary gear set
Data Source
AI summary
An electric transmission (16) for a motor vehicle drive train (12) includes a transmission input shaft (24) for operatively connecting the electric transmission to an electric prime mover (14), a reduction gear (26) for reducing a rotational speed of the electric prime mover, a transmission (28) for establishing gear steps, including a first planetary gear set (RS1) and a second planetary gear set (RS2), a first output shaft (34) and a second output shaft (36) for transmitting drive power from the electric transmission, and a plurality of shift elements (B, C, D) for engaging the gear steps. A planet carrier of the first planetary gear set is drivingly connected to a planet carrier of the second planetary gear set, and a sun gear of the first planetary gear set is drivingly connected to a ring gear of the second planetary gear set.