Superposition Gear Torque Vectoring Drive Unit
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Solution Overview
Problem
Existing electric torque vectoring transmissions in motor vehicles face high loads and complexity due to the use of bevel gear differentials and planetary gears, leading to inefficient torque distribution and increased component stress.
Innovation Solution
A drive device with a controllable shifting device in the superposition gear, allowing for switching between torque vectoring and hybrid modes, which reduces loads on the superposition gear by distributing additional torque evenly between output shafts, utilizing a torque-reducing transmission device and planetary gears to manage torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bevel gear differential is used for torque distribution, then torque can be distributed to two output shafts, but a high transmission ratio with many transmission steps is required and planetary gears are heavily loaded
Solution Approach 1:
The transmission system is segmented into distinct functional modules: a torque vectoring unit with planetary gears for differential torque distribution, and a separate superposition gear unit with an auxiliary motor for torque modulation. This segmentation allows each module to operate independently with optimized gear ratios, eliminating the need for a single complex high-ratio transmission system.
Solution Approach 2:
The superposition gear acts as an intermediary mechanism between the main differential and the output shafts. It receives torque from both the differential and the auxiliary motor, superimposes these torques, and transmits the combined torque to the output shafts. This intermediary structure enables precise torque control without requiring excessive transmission steps.
2Adaptability or versatility
If planetary gears are used in the superposition gear for torque superposition, then torque distribution can be controlled, but the planetary gears are subjected to high loads requiring larger component dimensions
Solution Approach 1:
The system dynamically adjusts torque distribution by controlling the auxiliary motor's output torque. The superposition gear's planetary gears experience variable loads depending on the auxiliary motor's contribution, allowing the system to optimize component sizing by keeping gear loads within acceptable dynamic ranges rather than designing for maximum static loads.
Solution Approach 2:
The patent replaces a purely mechanical torque distribution system with a hybrid system that uses an electric auxiliary motor to provide torque modulation. This substitution eliminates the need for complex mechanical transmission steps and reduces the load on planetary gears, as the motor directly provides the necessary torque adjustment without requiring high-ratio mechanical reduction.
3Power
If the superposition gear is designed to handle high wheel differential torque, then torque vectoring is effective, but the gear becomes large and complex to manufacture
Solution Approach 1:
The torque handling function is segmented between the main differential (which handles the bulk of wheel differential torque) and the superposition gear (which handles only the auxiliary torque modulation). This segmentation allows the superposition gear to be designed for lower power handling, significantly reducing its size and manufacturing complexity while maintaining effective torque vectoring capability.
Solution Approach 2:
The superposition gear is designed with multi-functionality, serving both as a torque superposition mechanism and as a compact transmission unit with integrated auxiliary motor coupling. This universal design approach simplifies manufacturing by consolidating functions into a single compact unit rather than requiring separate large-scale components for each function.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Drive unit for a motor vehicle, comprising a differential (3) for distributing a driving moment supplied via a drive shaft (4) to two output shafts (5, 6, 17, 21), and a superposition gear (7, 15) that is coupled to the differential (3), one of the output shafts (6, 17) and an additional motor (8, 16) in order to superimpose torques supplied by the output shaft (6, 17), the differential (3) and the additional motor (8, 16); the differential (3) is coupled to the superposition gear (7, 15) via a moment-reducing transmission device (9); the superposition gear (7, 15) comprises a switching device that can be controlled by a control device (10); in a first switched state of the switching device, the superposition gear superimposes the torques supplied by the output shaft (6, 17), the differential (3) and the additional motor (8, 16) in such a way that the distribution of the driving moments to the output shafts (5, 6, 17, 21) depends upon an additional torque applied by the additional motor (8, 16), and in a second switched state of the switching device, the superposition gear superimposes the torques supplied by the output shaft (6, 17), the differential (3) and the additional motor (8, 16) in such a way that the additional torque is evenly distributed to both output shafts (5, 6, 17, 21).