Jaw Coupling for Electric Drive Axle Decoupling
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Solution Overview
Problem
Hybrid vehicles face inefficiencies due to the inability to effectively decouple the electric machine from the drivable axle at high rotational speeds or during free rolling, leading to energy losses and compromised driving dynamics.
Innovation Solution
A disengageable mechanical jaw coupling is implemented between the electric machine and the drivable axle, allowing for engagement and disengagement based on vehicle operating states, such as acceleration and recuperation, to manage torque transmission and minimize mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the electric machine is continuously coupled to the drivable axle, then torque transmission is maintained, but energy losses occur at high rotational speeds and during free rolling
Solution Approach 1:
The coupling between the electric machine and drivable axle is segmented into engageable and disengageable states through the jaw coupling mechanism. This allows the system to separate the electric machine from the drivable axle when energy losses would occur, eliminating continuous co-rotation losses while maintaining torque transmission when needed.
Solution Approach 2:
The coupling system transitions from a static connected state to a dynamic state where the jaw coupling can engage and disengage based on operating conditions. This dynamic capability allows the system to adapt to high rotational speeds and free rolling conditions by disengaging the electric machine, thereby reducing energy losses.
2Power
If the jaw coupling is engaged during acceleration, then torque assistance is provided, but mechanical stress increases during engagement/disengagement cycles
Solution Approach 1:
The control system prepares for engagement by synchronizing the rotational speeds of the electric machine and drivable axle before actual engagement occurs. This preliminary speed matching reduces shock loads and mechanical stress during the engagement process, while still enabling effective torque assistance during acceleration.
Solution Approach 2:
The jaw coupling design incorporates mechanical elements that cushion the engagement process, reducing peak stresses during engagement and disengagement cycles. This allows the system to provide necessary torque assistance while protecting the mechanical components from excessive stress.
3Speed
If the electric machine operates at high rotational speeds, then vehicle speed increases, but the electric machine cannot deliver appreciable torque
Solution Approach 1:
The system dynamically adjusts the coupling state based on rotational speed. At high rotational speeds where the electric machine cannot deliver appreciable torque, the jaw coupling disengages to prevent energy losses from continuous co-rotation. This dynamic adaptation allows the vehicle to achieve high speeds while avoiding the limitation of electric machine torque delivery.
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 solution prevents continuous co-rotation and energy loss, enhances driving efficiency by converting kinetic energy during recuperation, and ensures safe operation by managing excessive braking torque, thereby improving energy utilization and driving comfort.
Implementation Method 1
a disengageable mechanical coupling is provided between the drivable axle and the electric machine, in particular designed as a jaw coupling
Implementation Method 2
a torque of the rotating axle is transmitted to the electric machine, which is thus able to recuperate kinetic energy of the vehicle
Data Source
AI summary
A drive device for a vehicle includes an electric machine and an axle which is drivable by the electric machine. A disengageable mechanical coupling is provided between the drivable axle and the electric machine. This coupling is designed as a jaw coupling.