Symmetrical Drive Axle Torque Vectoring
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Solution Overview
Problem
Existing electrically drivable vehicles face challenges in reducing space and weight requirements for drive components, particularly in the arrangement of electric machines and manual transmissions, which can lead to interruptions in traction torque during shifting, affecting vehicle stability and agility.
Innovation Solution
The implementation of symmetrical, three-speed manual transmissions with intercoupled planetary gearsets and a constant transmission stage, along with an axle differential gear, allows for torque vectoring and reduced installation space by using identical transmissions on both sides and integrating components coaxially with the rotors, minimizing axial offset and enabling efficient power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two separate manual transmissions are used for individual-wheel drive, then torque vectoring capability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent merges two separate manual transmissions into a single transmission unit that serves both drive wheels through a differential mechanism. The transmission housing contains two output shafts that connect to the left and right drive wheels, allowing torque vectoring functionality while eliminating the need for two completely separate transmission assemblies, thereby reducing overall device complexity and space requirements.
Solution Approach 2:
The single manual transmission is designed with multi-functionality to perform the work of two separate transmissions. It includes a differential mechanism with two output shafts that can independently control torque distribution to left and right drive wheels, enabling both individual-wheel drive and torque vectoring capabilities from one unified transmission unit.
2Adaptability or versatility
If three-speed transmissions with intercoupled planetary gearsets are used, then transmission ratio range is improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines two planetary gearsets into a single integrated transmission unit with shared components. The first and second planetary gearsets share a common housing, mounting structure, and lubrication system, allowing the transmission to achieve three different transmission ratios through a unified mechanism rather than two separate gearsets, thereby reducing manufacturing complexity while maintaining the desired transmission ratio range.
3Ease of operation
If dog clutch shifting mechanism is used, then shifting capability is improved, but traction torque continuity deteriorates during shifting
Solution Approach 1:
The patent introduces a friction clutch as an intermediary shifting mechanism between the input shaft and planetary gearsets. The friction clutch provides smooth torque transfer during gear changes, eliminating the abrupt torque interruption characteristic of dog clutch mechanisms. This allows for continuous traction torque delivery while maintaining the ability to shift between different transmission ratios, improving reliability during shifting operations.
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 enhances torque delivery, improves vehicle agility by allowing desirable yawing moments, reduces installation space, and maintains traction torque continuity during shifting, making it suitable for commercial vehicles with increased traction needs.
Implementation Method 1
both planetary gearsets are intercoupled, i.e. the first and second planetary gearsets form a linkage for shifting three gears or transmission ratios, respectively
Data Source
AI summary
A drive axle of an electrically drivable vehicle including first and second drive wheels (R1, R2), first and second manual transmissions (G1, G2) and first and second electrical machines (EM1, EM2) which each have a respective drive shaft (1a, 1b). The first electrical machine (EM1) drives the first drive wheel (R1), via the first manual transmission (G1), and the second electrical machine (EM2) drives the second drive wheel (R2), via the second manual transmission (G2). The manual transmissions are each designed as three-speed transmissions (G1, G2) which have identical transmission ratios (i1, i2, i3).