Electric Drive Unit Disconnect Clutch Park Lock
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Solution Overview
Problem
Existing electric drive units face issues such as torque constraints, wheel slip, increased system complexity, and back electromotive force (EMF) due to dual park lock systems, which affect mechanical stability, performance, and energy management.
Innovation Solution
An electric drive unit with multiple electric machines and disconnect clutches, where a first disconnect clutch couples the machines, allowing one to operate in generator mode while the other drives, and additional clutches are used to manage power transfer and park lock functionality, reducing EMF and system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two park lock devices are used in dual electric drive architectures, then park lock functionality is provided for both drive units, but wheel slip occurs until parking gears and pawls find their position to engage, and system complexity increases
Solution Approach 1:
The patent combines the park lock functionality into a single centralized mechanism that can lock both electric machines, eliminating the need for separate park lock devices at each drive unit. This merging approach reduces the number of components while maintaining the ability to provide park lock functionality for the entire vehicle.
Solution Approach 2:
The single park lock mechanism is designed to perform multiple functions by locking both electric machines through a unified system. This multi-functional approach allows one device to replace what would traditionally require two separate devices, reducing complexity while maintaining comprehensive park lock capability.
2Reliability
If two park lock devices are used in dual electric drive architectures, then park lock functionality is provided for both drive units, but additional control schemes and processing resources are demanded
Solution Approach 1:
The control functions for both park lock devices are merged into a single control scheme that manages one centralized mechanism. This consolidation reduces the number of control algorithms and processing resources required, as the system now controls one device instead of coordinating two independent devices.
3Power
If electric machines operate independently in dual-motor architecture, then motive power is provided to drive wheels, but energy is not conserved during certain operating conditions
Solution Approach 1:
The patent merges the operational control of both electric machines to enable energy recovery functionality. By coordinating the operation of the first and second electric machines, the system allows one machine to generate electricity during regenerative braking while the other provides propulsion, thereby conserving energy that would otherwise be lost.
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
Enhances powertrain efficiency, increases vehicle range, and improves mechanical stability by conserving energy and reducing EMF, while using a single park lock assembly to avoid redundant mechanisms.
Implementation Method 1
a first disconnect clutch configured to, in an engaged configuration, rotationally couple the first electric machine and the second electric machine
Implementation Method 2
operate one of the first and second electric machines in a generator mode while the other electric machine is operated in a drive mode
Implementation Method 3
disengage the second disconnect clutch and the third disconnect clutch. In this way, back EMF is reduced or avoided in some instances
Data Source
AI summary
Systems and methods for an electric drive unit. The electric drive unit includes, in one example, a first electric machine rotationally coupled to a first drive wheel via a first gear train and a second electric machine rotationally coupled to a second drive wheel via a second gear train. The electric drive unit further includes a disconnect clutch that is configured to selectively rotationally couple the first electric machine and the second electric machine and a park lock assembly that is coupled to one of the first gear train and the second gear train and is configured to inhibit rotation of the corresponding gear train.