Dual-Motor Planetary Gear Layout for Compact EV Torque Split
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Solution Overview
Problem
Existing electric drive systems for motor vehicles face challenges in achieving efficient operation while minimizing installation space requirements.
Innovation Solution
The system employs a coupling gear mechanism with coaxially arranged planetary gear sets and switching elements to transmit torque between rotors and vehicle wheels, utilizing stepped planetary gears to reduce axial space and incorporating transmission stages for efficient torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional electric drive systems are used, then driving performance is achieved, but installation space requirements increase
Solution Approach 1:
The patent combines two electric engines with their respective gear mechanisms into a single integrated drive unit. The first electric engine (18) with first planetary gear set (32) and the second electric engine (25) with second planetary gear set (34) are merged into one compact assembly, sharing common components such as the housing (24) and output shafts (33, 35), thereby reducing overall installation space while maintaining dual-engine power output capability
Solution Approach 2:
The patent implements a nested configuration where the first planetary gear set (32) and second planetary gear set (34) are arranged coaxially and nested within each other's spatial envelope. The planetary carriers (38, 44) are connected in series, with gear elements of one set positioned within the radial and axial boundaries of the other set, maximizing space utilization without compromising driving performance
2Use of energy by moving object
If multiple electric engines are used to improve efficiency, then energy efficiency increases, but device complexity increases
Solution Approach 1:
The coupling gear mechanism (30) serves multiple functions simultaneously: it acts as a differential gear when both electric engines are operating, as a single-engine gear mechanism when only one engine is active, and provides torque distribution to both output shafts (33, 35) regardless of which engine is driving. This multi-functionality allows the system to achieve energy efficiency through selective engine operation without requiring separate gear mechanisms for each operating mode
Solution Approach 2:
The patent employs switching elements (SE1, SE2, SE3) that dynamically reconfigure the torque transmission paths based on operating conditions. These switching elements can engage or disengage specific gear elements and carriers within the planetary gear sets, allowing the system to adapt its internal configuration for optimal efficiency in different driving scenarios without increasing permanent structural complexity
3Area of stationary object
If compact gear mechanisms are used to reduce space, then installation space decreases, but manufacturing complexity increases
Solution Approach 1:
The compact drive unit is segmented into modular components: first electric engine (18) with its planetary gear set (32), second electric engine (25) with its planetary gear set (34), coupling gear mechanism (30), and switching elements (SE1, SE2, SE3). Each module can be manufactured and tested independently, then assembled into the final integrated unit. This segmentation reduces manufacturing complexity despite the compact overall design
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
This configuration allows for a compact, high-performance electric drive system with efficient torque distribution and reduced weight, enabling energy-saving and performance modes for enhanced driving dynamics.
Implementation Method 1
a first electric engine (18), which has a first rotor (22). The first rotor (22) can be driven by means of a first stator (20) and can thus be rotated around a first engine rotational axis, relative to the first stator (20)
Data Source
AI summary
An electric drive system for a motor vehicle includes a first electric engine and a second electric engine. A coupling gear mechanism has two output drive shafts configured to discharge output drive torques from the coupling gear mechanism. A first planetary gear set has a first element, a second element, and a third element connected in a rotationally fixed manner to a first of the output drive shafts. A second planetary gear set has a fourth element, a fifth element connected in a rotationally fixed manner to the second element, and a sixth element connected in a rotationally fixed manner to the second output drive shaft.