Scissoring Mechanism for eVTOL Lift Fan Blade Deployment
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Solution Overview
Problem
Existing scissoring mechanisms for lift fans in electric aircraft deploy at high speeds, requiring significant torque and causing stress and noise, and do not allow for proper fan alignment before reaching operating speed.
Innovation Solution
A scissoring mechanism that deploys blades at near-zero speed, utilizing a positioning mechanism to keep blades in a stowed configuration and a latch mechanism to lock them in a deployed configuration, eliminating the need for additional actuators and reducing stress and noise by allowing for pre-alignment before spinning up to full speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If existing scissoring mechanisms deploy blades at high speeds, then deployment speed is improved, but stress and noise increase significantly
Solution Approach 1:
The patent applies preliminary action by using a positioning mechanism to pre-align the blades into the desired deployed configuration before the motor begins rotating. This allows the blades to be correctly positioned at near-zero speed, eliminating the need for high-speed deployment and thereby reducing stress and noise during the deployment process.
2Force
If existing scissoring mechanisms require torque to deploy blades, then deployment capability is improved, but impact events and stresses increase
Solution Approach 1:
The positioning mechanism performs the alignment action before motor rotation begins, so that when the motor starts at near-zero speed, the blades are already in the correct configuration. This eliminates the need for high-torque impact events that would otherwise be required to force the blades into position during rotation.
Solution Approach 2:
The positioning mechanism acts as an intermediary device that facilitates blade alignment without requiring the motor to provide high torque. It mediates between the stationary blades and the rotating motor, enabling gentle deployment at near-zero speed.
3Loss of time
If existing scissoring mechanisms deploy blades at high speed, then deployment time is reduced, but fan alignment precision deteriorates
Solution Approach 1:
The positioning mechanism achieves precise fan alignment before the motor begins rotating at operating speed. This preliminary positioning ensures that the blades are correctly aligned in the deployed configuration, and since the motor starts at near-zero speed, the precise alignment is maintained without the disturbances that would occur during high-speed deployment.
Data Source
AI summary
Embodiments provide scissoring mechanisms for a vertical lift fan of an electric aircraft (e.g., a vertical take-off-landing eVTOL aircraft) where the blades of the vertical lift fan can be opened at almost zero speed. Exemplary scissoring mechanisms have position locking features that keep the collapsed blades in the low drag orientation once closed (e.g., in the stowed position). As a result, the scissoring mechanisms do not cause large impulses during opening and closing that cause large stresses and noise. In addition, the scissoring mechanisms provide an opportunity to check that the fans are opened properly prior to spinning them to the full operating speed. The scissoring mechanisms may not require an extra actuator, and rely on the propulsion motor.