Method and device for reducing vibrations
First Claim
1. A device for reducing vibrations of a. structure along a vibration propagation axis comprising an elongate spring having a central region with a connection for a structure for reducing vibration of said structure, two vibrating bodies each disposed at one of two opposite end portions of the spring, means for measuring movements of each of the vibrating bodies with respect to the central region of the spring, phase detectors for measuring phase difference between the movements of each of the vibrating bodies and the central region of the spring respectively, an amplitude controller for measuring amplitude difference between the movements of the vibrating bodies at the end portions of the spring and means for modifying resonance characteristics of an assembly of the spring and the vibrating bodies to reduce vibrations in the structure as a function (1) of a measured phase difference between the respective movements at the vibrating bodies and the movement at the central region of the spring and (2) of the amplitude difference between the movements of the vibrating bodies at the end portions of the spring.
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Accused Products
Abstract
A device and method for reducing vibrations of a structure along an axis of vibration propagation, in particular in a helicopter, wherein two vibrating members of masses m1 and m2 are located at the ends of a spring, the spring and/or the masses being so constructed that the resonance characteristics of the assembly may be variably adjusted within a range decisive for the reduction of vibrations of the structure. The phases of the movement of the two masses and of a central point of the spring connected to the structure are measured by accelerometers and the differences of phase angle compared to the base point are maintained at 90° by moving the masses using motors to bring about the necessary change in resonance of the assembly.
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Citations
14 Claims
- 1. A device for reducing vibrations of a. structure along a vibration propagation axis comprising an elongate spring having a central region with a connection for a structure for reducing vibration of said structure, two vibrating bodies each disposed at one of two opposite end portions of the spring, means for measuring movements of each of the vibrating bodies with respect to the central region of the spring, phase detectors for measuring phase difference between the movements of each of the vibrating bodies and the central region of the spring respectively, an amplitude controller for measuring amplitude difference between the movements of the vibrating bodies at the end portions of the spring and means for modifying resonance characteristics of an assembly of the spring and the vibrating bodies to reduce vibrations in the structure as a function (1) of a measured phase difference between the respective movements at the vibrating bodies and the movement at the central region of the spring and (2) of the amplitude difference between the movements of the vibrating bodies at the end portions of the spring.
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11. A method for reducing vibrations of a helicopter structure comprising connecting the helicopter structure to a central region of an elongate spring, measuring the movements of two vibrating members of masses m1 and m2 attached at ends of the spring relative to a movement of the central region of the spring and modifying resonance characteristics of a system consisting of the spring and the vibrating members by correcting variables derived from phase differences between the movements of the vibrating members and the movement at the central region of the spring respectively until a target phase difference value of 90°
- therebetween is attained and also by correcting said variables in dependence on an amplitude difference between the movements of the vibrating members until a set amplitude difference value is attained.
- View Dependent Claims (12, 13, 14)
Specification