Hybrid Drive Mechanical Disconnect System for Back-Driving Prevention
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Solution Overview
Problem
Conventional hybrid propulsion systems lack a reliable method to disconnect the electrically driven motor from the shaft, particularly in scenarios where system failure occurs, necessitating a mechanism to prevent back-driving and allow continued operation with a fuel-powered engine.
Innovation Solution
A hybrid drive system incorporating a mechanical disconnect system with a clutch mechanism and a rotor electromagnetic property modifying system, enabling mechanical and electromagnetic decoupling of the rotor from the shaft, allowing the fuel-powered engine to drive the system without the electric motor acting as a generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrical machine is permanently connected to the shaft, then the system structure is simple, but the system cannot be disconnected in failure scenarios allowing the fuel-powered engine to continue operation
Solution Approach 1:
A mechanical disconnect system acts as an intermediary between the electrical machine and the shaft. This system includes a clutch mechanism with engagement and disengagement states, allowing selective connection or disconnection of the electrical machine from the shaft while the fuel-powered engine continues to drive the propeller
Solution Approach 2:
The drivetrain is segmented into separable components: the shaft, the electrical machine, and the mechanical disconnect system. This segmentation allows the fuel-powered engine to remain connected to the propeller while disconnecting the electrical machine in failure scenarios
2Reliability
If the clutch mechanism is engaged to connect the rotor to the shaft, then mechanical power transmission is efficient, but the electrical machine cannot be disconnected when needed
Solution Approach 1:
The clutch mechanism serves as a controllable intermediary that can be engaged to connect or disengaged to disconnect the electrical machine from the shaft, providing reliable disconnection capability while maintaining a relatively simple structural implementation
Solution Approach 2:
The mechanical disconnect system transitions between two dynamic states: engaged state where the clutch connects the rotor to the shaft for normal operation, and disengaged state where the clutch disconnects them for failure scenarios. This dynamic state change enables flexible system response
3Object-affected harmful factors
If the rotor is permanently coupled to the shaft, then the system has fewer moving parts, but back-driving prevention is not achieved
Solution Approach 1:
The mechanical disconnect system with over-running clutch acts as a mediator that allows the propeller to drive the shaft freely while preventing the shaft from driving the rotor. This one-way torque transmission capability blocks back-driving to the electrical machine while maintaining simple operational characteristics
4Loss of energy
If the electrical machine remains connected during fuel-powered operation, then the system structure is simpler, but the electrical machine acts as an unwanted generator
Solution Approach 1:
The mechanical disconnect system serves as an intermediary that physically separates the electrical machine from the shaft's rotational energy source. When disengaged, it prevents the propeller-driven shaft from driving the rotor and generating unwanted electrical energy, while keeping the overall system structure relatively simple
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
Enables safe disconnection of the electric motor from the driveline, preventing back-driving and allowing the fuel-powered engine to maintain propulsion while preventing electrical output from the stator, thus ensuring system reliability and safety in failure scenarios.
Implementation Method 1
The clutch mechanism can be an over-running clutch connected between the shaft and the rotor. The over-running clutch can be configured to allow torque to be applied in only one direction such that the rotor can drive the shaft, but shaft cannot drive the rotor.
Implementation Method 2
The clutch mechanism can include a hydraulic coupling disposed around a rotor fan and a shaft fan. The hydraulic coupling can be configured to be sealed to the rotor and the shaft to retain a liquid therein when in a flooded state. The rotor fan and the shaft fan can be configured to be fluidly coupled in the flooded state such that the rotor fan drives the shaft fan
Data Source
AI summary
A hybrid drive system can include a shaft, an electrical machine comprising a rotor and a stator, and a mechanical disconnect system connecting the rotor to the shaft. The mechanical disconnect system is configured to mechanically connect the rotor to the shaft in a first state and to mechanically disconnect the rotor from the shaft in a second state such that rotor does not drive the shaft or such that the rotor is not driven by the shaft. The rotor can be a permanent magnet rotor, for example.