Electric Vehicle Drivetrain Planetary Differential Torque Vectoring
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Solution Overview
Problem
Existing drivetrains for electrically driveable motor vehicles, particularly those used in earth-moving and agricultural vehicles with four-wheel drive, face inefficiencies in managing different driving states and torque distribution between axle sections, limiting their operational efficiency and dynamic performance.
Innovation Solution
A drivetrain configuration featuring a planetary-type differential with two outputs connected to axle sections, allowing torque distribution and additional torque vectoring capabilities, along with the use of two electric machines and switchable clutches for optimized operation in various driving states, enabling independent wheel drive and efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional drivetrain with two electric machines and spur gearing is used, then torque can be transmitted to both axles, but the structural complexity increases and space requirements expand
Solution Approach 1:
The patent combines the differential function and transmission function into a single integrated planetary gear set. The planetary gear set serves both as the differential mechanism for torque distribution and as the transmission for speed/torque conversion, eliminating the need for separate differential and transmission assemblies. This merging reduces structural complexity while maintaining full torque transmission capability to both axles.
Solution Approach 2:
The planetary gear set is designed to perform multiple functions simultaneously: it acts as a differential mechanism for torque distribution between wheels, a transmission for speed and torque conversion, and a compact housing for both functions. This multi-functionality allows the drivetrain to maintain high power transmission capability while reducing overall device complexity and space requirements.
2Adaptability or versatility
If torque is distributed to both axle sections through a conventional differential, then both wheels can rotate at different speeds, but additional torque vectoring capability is limited
Solution Approach 1:
The patent introduces switchable clutches that can dynamically change the torque distribution mode. The clutches can be engaged or disengaged based on driving conditions, allowing the system to switch between different torque distribution strategies. This dynamic control capability provides adaptability for various driving states while keeping the mechanical structure relatively simple.
Solution Approach 2:
The control system monitors driving conditions and automatically adjusts clutch engagement states to optimize torque distribution. Based on feedback from sensors detecting wheel speed, acceleration, and driving mode, the control unit modulates the clutches to achieve optimal torque vectoring without requiring complex mechanical torque vectoring mechanisms.
3Adaptability or versatility
If switchable clutches are added for torque vectoring, then torque distribution flexibility improves, but device complexity increases
Solution Approach 1:
The drivetrain is segmented into modular components with independent control: the planetary gear set, the clutches, and the control unit. Each component performs a specific function and can be controlled independently. This segmentation allows the torque vectoring capability to be added through simple clutch engagement/disengagement logic rather than requiring a completely reworked mechanical system, thus limiting the increase in overall device complexity.
Data Source
AI summary
A drive train (2) of a purely electrically drivable motor vehicle has at least one electric machine (13, 14), a transmission (21), a planetary differential (22) and a drivable axle (2). The axle (2) can be driven by the electric machine (13, 14) via the transmission (21) and the differential (22). The planetary differential (22) has an input (32, 33) connected to the electric machine (13, 14), a first output (28, 34, 35, 36, 37, 38) connected to a first section (4) of the drivable axle (2), and a second output (30, 31, 42) connected to a second section (5) of the drivable axle (2). Rotational axes of the input and outputs of the planetary differential (22) form an intermediate axis (53) arranged between an axle (15) of a rotor (17) of the electric machine (13, 14) and the drivable axle (2).