Propulsion Unit Foldable Propeller Blades With Controlled Pivoting
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Solution Overview
Problem
Existing foldable blade propeller systems in propulsion units for aircraft can inadvertently exert forces on blades during accidental folding, affecting aerodynamic performance and causing drag or flow disturbances, and there is a need for a system that ensures blades pivot without forced movement regardless of their angular position.
Innovation Solution
A propulsion unit with a folding device featuring a transmission system using a movable control member, such as a slider, actuated by a cam and cam follower, which controls blade pivoting without forcing on the blades, and includes position detection and mechanical locking mechanisms to ensure blades remain in deployed or folded positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a folding device is used to pivot blades between deployed and folded positions, then the propeller can be removed from the local flow to reduce drag, but the folding device may exert unwanted forces on the blades when accidentally triggered, affecting aerodynamic performance
Solution Approach 1:
The patent introduces a control member as an intermediary element between the folding actuator and the blade. This control member is radially slidable within the blade cuff and connected to the blade via a link. The intermediary control member allows the folding force to be applied only when the blade is in the correct angular position, preventing unwanted forces during accidental triggering while still enabling effective folding when needed
Solution Approach 2:
The patent changes the parameter of force application timing by using a control member with extreme positions corresponding to different blade angular positions. The link can only transmit folding force when the control member is in the external extreme position, which corresponds to the blade being in the correct angular position. This parameter change ensures that folding forces are only applied when intended, eliminating unwanted forces during accidental triggering
2Ease of operation
If the blade is pivotably mounted with respect to the blade cuff about a folding axis, then the blade can be folded longitudinally against the nacelle, but the blade may be forced to pivot at incorrect angular positions causing aerodynamic interference
Solution Approach 1:
The control member serves as an intermediary that mediates between the folding actuator and the blade pivot. It is radially slidable within the blade cuff with extreme positions corresponding to deployed and folded blade states. The link connecting the control member to the blade can only effectively transmit force when the control member is in the external extreme position, ensuring the blade is at the correct angular position before folding begins
Solution Approach 2:
The system performs a preliminary check of the blade angular position through the control member's radial position within the blade cuff. Before the folding force can be transmitted to the blade, the control member must be in the external extreme position, which corresponds to the blade being in the correct angular position. This preliminary action prevents forced blade movement at incorrect angular positions that would cause aerodynamic disturbances
Data Source
AI summary
A propulsion unit with a propeller is provided, having a nacelle and a propeller rotatably mounted in the nacelle by a hub. The propeller includes blades mounted in a blade cuff pivotable about a pitch axis relative to the hub, each blade being pivotable relative to the cuff about a folding axis. The propulsion unit can further include a folding device that comprises an actuator for folding the blades. The folding device can include a control member rotationally affixed to the blade cuff and driven by the actuator, and a connecting rod pivotably mounted, on the one hand, on a root of the associated blade and, on the other hand, on the movable control member.