Circular Force Generator Bearing Reduction for Vibration Control
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Solution Overview
Problem
Existing systems for controlling helicopter vibrations are inefficient in minimizing vibrations, particularly at low force operating conditions, and often result in larger residual vibrations compared to the main rotor, leading to equipment and occupant fatigue, and structural damage.
Innovation Solution
A compact and modular circular force generator with a smaller bearing diameter, integrated high-accuracy servo controller using Hall-effect sensors, and a micro-controller for precise control of rotating forces, allowing for efficient vibration cancellation in a weight-optimized and cost-effective manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional circular force generators are used with larger bearing diameters, then load capacity and durability are improved, but power requirements and weight increase
Solution Approach 1:
The patent changes the bearing diameter parameter from conventional large sizes to smaller sizes (e.g., 6mm to 12mm range), which reduces the moment of inertia and power requirements while maintaining adequate load capacity through optimized bearing selection and arrangement. This parameter change directly addresses the contradiction between strength and energy consumption.
Solution Approach 2:
The patent divides the force generation function across multiple circular force generators with smaller bearings rather than using single large-bearing generators. This segmentation allows the system to achieve the required total force output while each individual generator operates with lower power requirements and reduced weight.
2Force
If conventional circular force generators are used, then force output is achieved, but residual vibrations increase especially at low force operating conditions
Solution Approach 1:
The patent implements feedback control systems that continuously monitor the actual force output and vibration levels, then adjust the operating parameters of the circular force generators to minimize residual vibrations. This feedback mechanism ensures accurate vibration cancellation even at low force operating conditions where conventional systems struggle.
Solution Approach 2:
The patent uses dynamically adjustable operating parameters including variable rotational speeds and phase angles of the eccentric masses. This dynamic control allows the system to optimize performance across different operating conditions, particularly improving low-force operation by adjusting the rotational characteristics to minimize harmful vibrations.
3Strength
If larger bearing diameters are used, then mechanical strength and load capacity are improved, but device weight and size increase
Solution Approach 1:
The patent systematically reduces the bearing diameter parameter from conventional sizes to smaller dimensions, which directly reduces the weight of each circular force generator. The smaller bearings (6mm to 12mm range) significantly reduce the moment of inertia and overall device weight while maintaining sufficient mechanical strength through proper bearing selection and structural design.
Solution Approach 2:
By dividing the total force generation requirement across multiple smaller generators with reduced bearing sizes, the patent achieves the necessary mechanical strength distribution without the weight penalty of single large-bearing systems. This segmented approach optimizes the weight-strength ratio.
4Measurement precision
If precise control of rotating force magnitude and phase is implemented, then vibration control accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses feedback control with sensors to monitor force output and position, providing precise control accuracy. The feedback mechanism automatically compensates for variations and maintains high precision without requiring overly complex control algorithms or additional mechanical components.
Solution Approach 2:
The patent replaces complex mechanical positioning mechanisms with electronic control of the eccentric mass rotation. By using electric motors with electronic controllers to precisely regulate rotational speed and phase angle, the system achieves high control accuracy while reducing mechanical complexity compared to traditional mechanical adjustment mechanisms.
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 power requirements, noise, and heat generation, enabling extended temperature operation and longer lifespan, while minimizing vibrations and force distortion, thus improving the structural integrity and comfort of helicopter operations.
Implementation Method 1
a high accuracy servo controller configured to control the rotating force magnitude and a rotating force phase of the rotor, the control system comprising a Hall-effect sensor servo control
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5A
AI summary
A circular force generator (CFG) (100) is provided for use in an active vibration control system. The CFG comprises a component housing, and a center shaft (120) positioned in a fixed relationship with respect to the component housing. The CFG further comprises a pair of motors (110) each having a rotor (116) and a fixed stator (112), the stator mounted to endplates (114). A rotating mass (150) is eccentrically connected to each rotor (116) such that rotation of the rotor (116) about the shaft (120) generates a circular force with a rotating force magnitude and a controllable rotating force phase. The rotor (116) of each motor (110) is coupled for rotation about the center shaft (120) by a bearing (130) mounted inside the motor (110).