Variable-Speed Propeller Thrust Control for Noise Reduction
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Solution Overview
Problem
Existing thrust generating devices for rotorcraft face challenges in reducing noise while maintaining sufficient thrust, as lowering propeller rotational speed limits thrust capacity and increasing propeller size increases weight.
Innovation Solution
A thrust generating device with a propeller, motor, actuator, and controller that allows for two control modes: maintaining propeller rotational speed at a reference value to control thrust through blade pitch angle adjustments, or increasing rotational speed beyond the reference value to generate greater thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the propeller rotational speed is reduced to decrease noise, then noise is reduced, but the maximum thrust capacity is reduced
Solution Approach 1:
The patent changes the operational parameters by allowing the propeller rotational speed to vary dynamically between a reference value (for noise reduction) and higher values (for maximum thrust capacity). The controller adjusts the rotational speed based on required thrust levels, enabling the system to operate at lower speeds during normal conditions to reduce noise while being capable of increasing speed when maximum thrust is needed.
2Force
If the propeller size is increased to increase maximum thrust capacity, then thrust capacity is increased, but the weight of the rotorcraft increases
Solution Approach 1:
The patent applies dynamics by making the propeller rotational speed variable rather than fixed. The controller dynamically adjusts the rotational speed based on the required thrust, allowing the existing propeller size to deliver variable thrust capacity from a reference level up to a maximum level. This eliminates the need to oversize the propeller for maximum thrust while keeping weight low, as the system can achieve maximum thrust temporarily when needed by increasing rotational speed.
3Ease of operation
If the pitch angle of each blade is adjusted to control thrust, then thrust control is improved, but the device complexity increases
Solution Approach 1:
The patent makes the control system multi-functional by using the existing pitch angle adjustment mechanism for both thrust control and rotational speed regulation. The controller integrates multiple functions (thrust control, speed control, and actuator control) into a single system that can operate in different modes (first control for noise reduction, second control for maximum thrust), reducing the need for separate dedicated systems for each function.
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 effectively reduces noise and achieves the required thrust by dynamically adjusting propeller speed and blade pitch, while maintaining a torque margin to prevent propeller responsiveness deterioration.
Implementation Method 1
a propeller including one or a plurality of blades and configured to generate thrust in a vertical direction
Implementation Method 2
a propeller including one or a plurality of blades and configured to generate thrust in a vertical direction
Implementation Method 3
a motor configured to rotate the propeller
Implementation Method 4
an actuator configured to change a pitch angle of each of the blades
Data Source
AI summary
A controller of a thrust generating device executes one of first control of controlling thrust by changing the pitch angle of each blade while maintaining the rotational speed of a propeller at a reference value, or second control of allowing the thrust greater than the thrust generated in the first control to be generated by making the rotational speed of the propeller larger than the reference value.