Annular Propeller Belt Drive for Low-Noise Drone Propulsion
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Solution Overview
Problem
Existing personal air mobility aircraft and drones face inefficiencies in propulsion rotors, including poor thrust/weight ratio, high noise levels, complex motor systems, and reduced autonomy.
Innovation Solution
The aircraft incorporates an annular propeller system with a rotor ring driven by a belt transmission from an electric motor, featuring variable pitch blades and supported by wavy leaf springs or cup springs, with a streamlined airflow duct for enhanced efficiency and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional propulsion rotors are used in personal air mobility aircraft, then the motor system becomes complex and noise increases, but the thrust/weight ratio and autonomy are reduced
Solution Approach 1:
The propulsion system is segmented into modular components: electric motor, belt transmission system, and annular propeller with multiple independent blades. Each blade can be independently controlled and adjusted, allowing the system to achieve high thrust/weight ratio while maintaining simplicity through modular architecture rather than integrated complexity
Solution Approach 2:
The patent replaces complex direct-drive mechanical rotor systems with an electric motor coupled through a belt transmission system. This substitution of mechanical coupling methods simplifies the motor system architecture while maintaining or improving thrust efficiency, as the belt transmission allows for smoother power delivery and reduced mechanical stress
2Reliability
If traditional propulsion rotors are used, then the drive system becomes complex, but noise levels increase and reliability decreases
Solution Approach 1:
The belt transmission system incorporates self-tensioning mechanisms and automatic alignment features that allow the drive system to maintain optimal performance without complex external control systems. The wavy leaf springs provide automatic cushioning and alignment, reducing wear and improving reliability while keeping the overall system simple
Solution Approach 2:
Wavy leaf springs are incorporated into the blade support system to provide beforehand cushioning against vibrations and shocks. This pre-engineered shock absorption reduces stress on the drive system components, improving reliability while maintaining simplicity through passive mechanical cushioning rather than active control systems
3Object-generated harmful factors
If conventional rotor designs are used, then construction becomes complicated and costly, but noise levels remain high
Solution Approach 1:
The annular propeller design utilizes curved, aerodynamic blade shapes that naturally reduce turbulence and noise generation. The circular annular structure itself promotes smooth airflow patterns, reducing vortex formation and associated noise. These curved geometries are manufactured using standard composite layup techniques, maintaining ease of construction while achieving low noise operation
Solution Approach 2:
The patent employs variable pitch blades where the blade angle can be adjusted to optimize performance across different operating conditions. By changing the blade pitch parameter, the system maintains efficient, low-noise operation whether during takeoff, cruise, or landing, without requiring complex mechanical structures. The variable pitch mechanism uses simple cable-driven or spring-loaded adjustment systems
4Productivity
If high efficiency propulsion is achieved through complex motor systems, then thrust/weight ratio improves, but autonomy is reduced
Solution Approach 1:
The electric motor and belt transmission system serves multiple functions simultaneously: it provides efficient propulsion, allows for variable blade pitch control, enables individual blade adjustment for optimization, and incorporates vibration damping through the wavy leaf springs. This multi-functionality achieves high propulsion efficiency without adding separate systems that would increase weight and reduce autonomy
Solution Approach 2:
The variable pitch capability allows the propulsion system to optimize its parameters for different flight phases. During climb, blades are set to high pitch for maximum thrust; during cruise, pitch is reduced for efficiency; during landing, pitch is adjusted for controlled descent. This dynamic parameter adjustment maximizes energy utilization across all operations, extending autonomy while maintaining high productivity when needed
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 achieves a high thrust/weight ratio, low noise operation, and simplified, reliable drive system, along with improved lift and anti-stall characteristics, enhancing the aircraft's autonomy and performance.
Implementation Method 1
a rotor ring (2A) driven by a belt transmission (5) from an electric motor (P)
Implementation Method 2
supported by wavy leaf springs or cup springs
Implementation Method 3
with a streamlined airflow duct for enhanced efficiency
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An aircraft, in particular a personal air mobility aircraft or a drone, comprising one or more annular propellers (2), with one or more blades (3) extending radially from a rotor ring body (2A) towards the axis (4) of the rotor ring (2A), and one or more belt transmissions (5), which connect the rotor ring (2A) of each annular propeller (2) with the output shaft of a motor unit (P) including an electric motor. Various alternative techniques are provided to support the rotor ring (2A) in rotation. Various aircraft configurations are envisaged, including a vertical take-off and horizontal flight configuration. The aircraft surfaces are covered by groups of photovoltaic solar cells (PV) connected both to a main battery pack (201) for powering the electric motors (M) that drive the annular propellers, and to an auxiliary electric battery (202) for powering the on-board electrical circuit, by means of DC-DC converters (203) controlled by an electronic board (204).