Variable Pitch Propeller Torque Compensation Mechanism
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Solution Overview
Problem
Existing propeller pitch change mechanisms face significant challenges in overcoming the total twisting moment (TTM) that resists blade motion, leading to parasitic energy loss due to the need to counteract centrifugal, aerodynamic, and frictional forces, resulting in inefficient operation and larger actuation structures.
Innovation Solution
A propeller assembly with a pitch change mechanism that includes a motor-driven gear transmission system, where a compensation shaft and bevel gear system reduce the force required to change the pitch angle by addressing the twisting moment, allowing the motor to primarily overcome frictional forces, thereby enhancing efficiency and reducing the size of the actuation package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pitch change mechanism drives the blade to rotate within the hub, then the pitch angle of the blades can be adjusted to provide adjustable thrust, but the mechanism must overcome the total twisting moment (centrifugal, aerodynamic, and friction forces) which causes parasitic energy loss and requires larger actuation structures
Solution Approach 1:
The patent applies counterweight by introducing a compensation blade with mass that generates centrifugal force to counteract the total twisting moment on the propeller blade. The compensation blade is positioned and dimensioned so its centrifugal force creates a twisting moment that balances the aerodynamic and friction forces, allowing the pitch change mechanism to operate with minimal energy consumption.
Solution Approach 2:
The patent converts the harmful centrifugal force that normally contributes to the twisting moment problem into a beneficial counteracting force. By strategically placing a compensation mass on a compensation blade, the previously problematic centrifugal effect is harnessed to automatically balance the aerodynamic and friction forces, eliminating parasitic energy losses.
2Ease of operation
If the pitch change mechanism overcomes all forces including centrifugal and aerodynamic twisting moments, then the blade pitch can be changed, but the actuation structure becomes larger and more complex
Solution Approach 1:
The compensation blade with strategically positioned mass acts as a counterweight that automatically balances the aerodynamic and friction forces during blade rotation. This eliminates the need for complex actuation structures designed to overcome these forces, simplifying the pitch change mechanism while maintaining ease of operation.
Solution Approach 2:
The system achieves self-service by using the rotation of the propeller itself to generate the compensating centrifugal force through the compensation blade. The mechanism automatically balances the twisting moment during operation without requiring external intervention or complex control systems, reducing actuation structure complexity.
3Reliability
If the pitch change mechanism is designed to overcome the large total twisting moment, then reliable pitch control is achieved, but parasitic loss of energy occurs and operational efficiency decreases
Solution Approach 1:
The compensation blade creates a counteracting twisting moment that balances the aerodynamic and friction forces, ensuring reliable pitch control while eliminating parasitic energy losses. This maintains dependable blade pitch adjustment without the energy penalties that would reduce operational efficiency.
Solution Approach 2:
The patent transforms the previously harmful centrifugal forces and aerodynamic resistance into a beneficial self-balancing mechanism. By using the compensation blade to generate counteracting centrifugal force, the system achieves reliable pitch control without parasitic energy losses, thereby improving operational efficiency.
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 solution significantly reduces the energy required to change the pitch angle, minimizing parasitic losses and enabling a more compact and efficient propeller pitch change mechanism by compensating for the twisting moment, resulting in improved operational efficiency.
Implementation Method 1
The drive input includes a drive input gear transmission to change a pitch angle of the blades when the blades are moved relative to the drive input by the pitch change mechanism
Data Source
Figure 1~2
AI summary
A propeller assembly (20) has a plurality of propeller blades (26), and a pitch change mechanism including at least one motor (48). A drive input (32) drives the plurality of propeller blades to rotate about a central drive axis (Y). The pitch change mechanism is operable upon driving of the motor to move the propeller blades about the drive axis relative to the drive input. The drive input includes a drive input gear transmission (62,68,56) to change a pitch angle of the blades when the blades are moved relative to the drive input by the pitch change mechanism. Further, a method of operating a propeller assembly to change a pitch angle is disclosed and claimed.