Two-Speed Electric Drive Assembly for Shift Without Torque Interrupt
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Solution Overview
Problem
Existing electric vehicle drive systems experience torque interruptions during gear shifts due to the time it takes to disengage and engage gears, and the need to bleed off energy from the electric motor, which can damage electronic components if not properly managed.
Innovation Solution
A two-speed electric drive assembly with two axial flux motors and a gearing arrangement that includes a freewheel gear mechanism, allowing for seamless gear transitions without physical shifting of gears, and utilizing one motor to generate electricity during transitions to mitigate energy pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional gear shifting is used in electric drive systems, then gear transitions can be achieved, but torque interruptions occur during shifting causing vehicle slowdown
Solution Approach 1:
The drivetrain is segmented into two independent motor systems (first axial flux motor with main gear, second axial flux motor with assist gear) that can operate independently or in parallel. During gear transitions, one motor can be disengaged while the other maintains power delivery, eliminating torque interruption and vehicle slowdown.
2Ease of operation
If control signals are transmitted from TCU to motor controller during gear shifts, then gear switching can be controlled, but computation and reaction time cause torque interrupt
Solution Approach 1:
The system performs preliminary synchronization of the assist gear with the intermediate driveshaft before engagement. Speed sensors continuously monitor rotational speeds and the control system pre-coordinates the motors so that when shifting is commanded, the gears are already synchronized and ready for immediate engagement, eliminating computation and reaction delays.
3Loss of energy
If the electric motor is turned into a generator to bleed off power during gear transitions, then energy can be dissipated, but energy pulses can damage electronic components
Solution Approach 1:
The assist gear acts as an intermediary mechanism that provides a mechanical path for energy dissipation during transitions. Instead of forcing the main motor into generator mode which creates damaging energy pulses, the assist gear mechanically absorbs and redirects energy during the transition period, protecting electronic components while still achieving gear switching.
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 reduces torque interruptions and energy pulse management issues, ensuring smoother gear shifts and protecting electronic components by maintaining power during transitions and minimizing regeneration mode.
Implementation Method 1
a first axial flux motor coupled to the main driveshaft... the first axial flux motor operates to rotate the main driveshaft
Implementation Method 2
a second axial flux motor coupled to the assist driveshaft... the second axial flux motor operates to rotate the assist driveshaft
Implementation Method 3
an assist gear mounted along the assist driveshaft and rotatable relative to the assist driveshaft... one of the main gear, assist gear, first intermediate gear or second intermediate gear is a freewheel gear
Data Source
AI summary
A two-speed electric drive assembly for vehicles includes a main driveshaft driven by a first axial flux motor where the main driveshaft extends coaxially through a hollow assist driveshaft driven by a second axial flux motor. The main driveshaft includes a main gear that is continuously meshed with an intermediate gear on an intermediate driveshaft. A freewheel gear is mounted around the hollow assist driveshaft and can be selectively coupled and decoupled with the hollow assist driveshaft by a shift mechanism. The freewheel gear is continuously meshed with an intermediate gear on the intermediate driveshaft. Another intermediate gear affixed to the intermediate driveshaft is continuously meshed with an output gear affixed to an output driveshaft. The two-speed electric drive assembly can selectively switch between speed mode and torque mode without torque interrupt.