Variable-Pitch Propeller Blade Radial Limiting Face Torque Transmission
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Solution Overview
Problem
Aircraft turbomachine propellers with variable pitch blades face challenges in maintaining control of pitch angle due to breakage of elements in the kinematic chain between the blade and the actuator or safety device, leading to potential loss of feathering capacity and hazardous drag conditions.
Innovation Solution
The propeller blade assembly includes radial limitation faces that cooperate with stop faces in a bowl to limit rotation in both directions around the wedging axis, providing a secondary path for torque transmission in case of breakage, ensuring continued control of the blade's pitch angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the free lower end of the root is used to transmit torque for blade angular setting, then the torque transmission is efficient, but the system loses reliability in case of breakage
Solution Approach 1:
The patent incorporates radial limiting faces and associated stop faces in advance during manufacturing, so that in the event of breakage of the free lower end of the root, the blade can automatically engage these pre-positioned features to maintain controlled rotation and feathering capacity without requiring complex detection or activation systems
Solution Approach 2:
The design includes backup engagement surfaces (radial limiting faces and stop faces) that are positioned in advance to provide a safety mechanism. These surfaces are prepared beforehand to absorb the shock of potential breakage and immediately provide a secondary torque transmission path, preventing complete loss of control
2Power
If remote counterweight systems are used with kinematic chains, then the actuator power can be reduced, but the system becomes vulnerable to breakage of intermediate parts
Solution Approach 1:
The patent extracts the critical torque transmission function from the potentially fragile kinematic chain and relocates it to a more robust interface between the bowl and blade root. By using direct engagement through radial limiting faces and stop faces, the design removes the vulnerable intermediate elements while maintaining the remote counterweight configuration's power reduction benefits
Solution Approach 2:
The radial limiting faces and stop faces act as intermediary elements that provide a reliable torque transmission path. These surfaces serve as a mediator between the bowl and blade root, ensuring that even if other components fail, the essential feathering function can be maintained through this intermediate engagement mechanism
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
This solution ensures the blade can maintain controlled rotation and pitch angle even if the free lower end of the foot breaks, preventing uncontrolled movement and drag-related hazards, thereby enhancing safety and operational stability.
Implementation Method 1
the root of the blade comprises at least one first radial limiting face which is intended to cooperate with at least one first associated radial stop face of the bowl to limit the rotation of the blade in a first direction around the setting axis relative to the bowl
Implementation Method 2
the free lower end of the root being fitted axially into a complementary housing of the bottom wall to connect the bowl and the blade in rotation around the setting axis
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to an assembly comprising a propeller blade (10) and its system (34) for angularly adjusting the pitch of the blade (10) comprising a bowl (42) which is radially delimited by an annular wall (44) extending about an axis (A) for adjusting the pitch of the blade (10), the bowl (42) comprising a bottom wall (46), a free lower end (28) of the root (14) being fitted axially into a complementary housing (56) of the bottom wall (46) in order to rotatably connect the bowl (42) and the blade (10) about the pitch-adjustment axis (A), characterised in that the root (14) of the blade (10) comprises a first limiting face (70A) that engages with a first abutment face (72A) of the bowl (42) to limit the rotation of the blade (10) in the event of breakage of the lower end (28) of the root.