| 摘要 |
A vibration isolation system wherein a vibrating mass such as a helicopter rotor-transmission assembly is spring coupled to a body to be isolated, such as the helicopter fuselage, at a plurality of coupling locations. Each coupling location includes a weighted lever arm pivotally connected to the vibrating mass and to the body and a coupling spring connected to the weighted lever arm for transmitting the rotor forces of the rotor-transmission assembly to the fuselage through the pivot connections on the lever arm. The coupling spring is in the form of an elongated spring arm connected at one end to the weighted lever arm and at the other end to the body through a pivot link, the latter being required to accommodate shortening of the spring during flexure. The spring forces transmitted to the fuselage through the coupling springs due to linear vibration forces are cancelled at the characteristic rotor frequency by equal and opposite inertial forces produced by the weighted lever arms. A modified system is disclosed wherein spring forces transmitted to the fuselage due to angular as well as linear vibration forces are isolated. In this system a second coupling spring is added to the basic spring arm arrangement such that the second spring flexes only in response to either the linear or angular vibratory component, but not to both. This causes the spring forces applied to the fuselage in response to angular vibration to be different from the spring forces applied due to linear vibration and this difference in spring forces establishes moment as well as linear force equilibrium such that the fuselage is completely isolated from angular as well as linear vibration. |
