Electric Propulsion Disconnect Clutch for Fault Torque Isolation
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Solution Overview
Problem
Existing electric propulsion systems require a mechanism to safely disconnect the electric machine from the drive mechanism to manage fault conditions and prevent damage, especially in systems with multiple electric machines.
Innovation Solution
A drive mechanism for electric propulsion systems that includes a drive shaft with an engagement means and a disconnect mechanism, featuring shaft gear rings and gear sets with specific axial lengths and spacings, and an overrunning clutch to ensure safe disconnection and torque control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a disconnect mechanism is implemented to safely disconnect the electric machine from the drive mechanism, then system safety and fault management are improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary disconnect mechanism comprising a disconnect actuator, a first gear ring, a second gear ring, and a one-way clutch that mediates between the electric machine and the drive mechanism. This intermediary structure enables safe disconnection during fault conditions while maintaining a relatively simple overall architecture by using passive mechanical elements rather than active control systems.
Solution Approach 2:
The disconnect mechanism is designed to operate automatically based on rotational direction without requiring external control signals. The one-way clutch and gear rings self-actuate to disconnect the electric machine from the drive mechanism when reverse rotation is detected, eliminating the need for complex sensor systems or control algorithms while maintaining high reliability.
2Adaptability or versatility
If multiple electric machines are connected to a single drive mechanism, then power output and versatility are improved, but the complexity of disconnection and fault management increases
Solution Approach 1:
The patent applies segmentation by providing each electric machine with its own independent disconnect mechanism featuring first and second gear rings. This modular approach allows each electric machine to be disconnected individually from the common drive mechanism, enabling flexible power output configurations while keeping the disconnection control simple and decentralized.
3Device complexity
If the electric machine is permanently connected to the drive mechanism, then structural simplicity is maintained, but the ability to manage fault conditions and minimize damage is reduced
Solution Approach 1:
The patent transforms the static permanent connection into a dynamic conditional connection. The disconnect mechanism remains structurally integrated with the drive mechanism but automatically changes its connection state based on operational conditions. The one-way clutch enables the gear rings to engage during normal operation and disengage during fault conditions, providing adaptive protection while maintaining structural simplicity.
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 proposed drive mechanism effectively manages the disconnection of electric machines from the drive shaft, minimizing damage and ensuring safe operation by controlling torque transmission and rotational direction.
Implementation Method 1
an overrunning clutch which couples the electric machine to the electric machine engagement element
Data Source
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AI summary
A drive mechanism (16) for an electric propulsion system (4) that comprises an electric machine (18) is disclosed. The drive mechanism comprises a drive shaft (10) with a longitudinal axis A, an engagement means, a disconnect mechanism (52), and an overrunning clutch (60). The engagement means comprises a drive shaft engagement element (56) and an electric machine engagement element (58). The drive shaft engagement element comprises a first and second shaft gear ring, and each shaft gear ring is supported on the drive shaft (10). Each shaft gear ring comprises a plurality of gear teeth (36) which are circumferentially disposed around the drive shaft, and the gear teeth extend radially outward from the drive shaft. The gear teeth of the first shaft gear ring have an axial length L1, and the first and second shaft gear rings are axially spaced from each other along the drive shaft by a distance L2. The electric machine engagement element comprises a first and second gear set, and the first and second gear sets each comprise a plurality of gear teeth (30) which are configured to mesh with the gear teeth of the first and second shaft gear rings respectively. The gear teeth of the first gear set have an axial length L3, and the first and second gear sets are separated from each other by a length L4 in the axial direction. Length L1 is less than length L4. Length L3 is less than length L2. The disconnect mechanism is configured to reversibly move one of at least part of the drive shaft engagement element and at least part of the electric machine engagement element relative to the other of the engagement elements in an axial direction between a first position and a second position. In the first position the gear teeth of the first shaft gear ring are meshed with the gear teeth of the first gear set and the gear teeth of the second shaft gear ring are meshed with the gear teeth of the second gear set, and in the second position the gear teeth of the first shaft gear ring are axially between the first and second gear sets and the gear teeth of the first shaft gear ring are not meshed with the gear teeth of the first or second gear sets. The electric machine is coupled to the electric machine engagement element through the overrunning clutch.