Apparatus for controlling active mounts
AssigneeLord Corporation
InventorsDouglas A. Swanson, Lane R. Miller
Life of this patent
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Abstract
An active isolator with a closed-loop feedback control system which uses an actuator in parallel spring relation to a static load spring to control the dynamic vibration transmitted from a vibrating device over a broad band frequency range. A collocated sensor is installed to sense the vibration of the isolated element and is amplified and fed, filtered and amplified again, reversed in sign and fed directly into the actuator. No external synchronizing signal or processor is needed. This simple active control is practical only where the combined series dynamic stiffness of the structure and vibrating body is much less than or much greater than the active mount's dynamic stiffness.
Claims16
An active mount exhibiting an uncontrolled, frequency-dependent dynamic stiffness K.sub.M (.OMEGA.) for reducing mechanical vibration transmitted within a mechanical system which includes said mount, a vibrating device exhibiting a frequency-dependent dynamic stiffness K.sub.E (.OMEGA.) and a support exhibiting a frequency-dependent dynamic stiffness K.sub.S (.OMEGA.), comprising:
- (a) spring means interconnecting said vibrating device and said support for providing passive support of a static load from said vibrating device;
- (b) an actuator for providing phased dynamic loads to counteract said mechanical vibration from said vibrating device and reduce vibration transmitted to said support, said actuator connected in parallel spring relation to said spring means;
- (c) a sensor collocated with said active mount for supplying an input signal to a simple closed-loop feedback control system;
- (d) said closed-loop feedback control system providing an output control signal to said actuator responsive to said collocated sensor and further including an amplifier which amplifies said input signal, and means for reversing the sign of said input signal;
- and,
- (e) said mechanical system having a natural frequency f.sub.n, said mechanical system being characterized by a ratio of a series dynamic stiffness K.sub.SD (.OMEGA.) to an elemental dynamic stiffness. K.sub.X (.OMEGA.), being related by an expression
- K.sub.SD (.OMEGA.)/K.sub.X (.OMEGA.).gtoreq.2 for .OMEGA..gtoreq.2f.sub.n
- where K.sub.X (.OMEGA.) is selected from the group consisting of K.sub.M (.OMEGA.) and K.sub.S (.OMEGA.) and D.sub.SD (.OMEGA.)=K.sub.Y (.OMEGA.)K.sub.Z (.OMEGA.)/[K.sub.Y (.OMEGA.)+K.sub.Z (.OMEGA.)] with K.sub.Y (.OMEGA.) and K.sub.Z (.OMEGA.) being a remaining two dynamic stiffness from a group consisting of K.sub.E (.OMEGA.), K.sub.M (.OMEGA.) and K.sub.S (.OMEGA.) after K.sub.X (.OMEGA.) has been designated, such that K.sub.X (.OMEGA.) is much softer than K.sub.SD (.OMEGA.) enabling the use of said simple closed-loop feedback control.
An active mount exhibiting an uncontrolled frequency-dependent dynamic stiffness K.sub.M (.OMEGA.) for reducing mechanical vibration transmitted within a mechanical system which includes said mount, a vibrating device exhibiting a frequency-dependent dynamic stiffness K.sub.E (.OMEGA.) and a support exhibiting a frequency-dependent dynamic stiffness K.sub.S (.OMEGA.), comprising:
- (a) a spring means interconnecting said vibrating device and said support for providing passive support of a static load from said vibrating device;
- (b) an actuator for providing phased dynamic loads to counteract said mechanical vibration from said vibrating device and reduce vibration transmitted to said support, said actuator connected in parallel spring relation to said spring means;
- (c) a force sensor collocated with said active mount for supplying an input signal indicative of a magnitude of a force experienced by said support to a simple closed-loop feedback control system;
- (d) said closed-loop feedback control system providing an output control signal to said actuator responsive to said collocated sensor and further including an amplifier which amplifies said input signal, and means for reversing the sign of said input signal;
- and,
- (e) said mechanical system having a natural frequency f.sub.n and being characterized by a ratio of series dynamic stiffness K.sub.SD (.OMEGA.) to mount stiffness K.sub.M (.OMEGA.).gtoreq.2 for .OMEGA..gtoreq.2f.sub.n, where K.sub.SD (.OMEGA.)=K.sub.E (.OMEGA.)K.sub.S (.OMEGA.)/[K.sub.E (.OMEGA.)+K.sub.S (.OMEGA.)], such that K.sub.M (.OMEGA.) is much softer than K.sub.SD (.OMEGA.) enabling the use of said simple closed-loop feedback control.
An active mount exhibiting an uncontrolled, frequency-dependent dynamic stiffness K.sub.M (.OMEGA.) for reducing mechanical vibration transmitted within a mechanical system which includes said mount, a vibrating device exhibiting a frequency-dependent dynamic stiffness K.sub.E (.OMEGA.) and a support exhibiting a frequency-dependent dynamic stiffness K.sub.S (.OMEGA.), comprising:
- (a) a spring means interconnecting said vibrating device and said support for providing passive support of a static load from said vibrating device;
- (b) an actuator for providing phased dynamic loads to counteract said mechanical vibration from said vibrating device and reduce vibrating transmitted to said support, said actuator connected in parallel spring relation to said spring means;
- (c) a motion sensor collocated with said active mount for supplying an input signal indicative of a magnitude of a movement experienced by said support to a simple closed-loop feedback control system;
- (d) said closed-loop feedback control system providing an output control signal to said actuator responsive to said collocated sensor and further including an amplifier which amplifies said input signal, and means for reversing the sign of said input signal;
- and,
- (e) said mechanical system being characterized by a ratio of series dynamic stiffness K.sub.SD (.OMEGA.) to support stiffness K.sub.S (.OMEGA.).gtoreq.2, for .OMEGA.>2f.sub.n, where K.sub.SD (.OMEGA.)=K.sub.E (.OMEGA.)K.sub.M (.OMEGA.)/[K.sub.E (.OMEGA.)+K.sub.M (.OMEGA.)], such that K.sub.SD (.OMEGA.) is much softer than K.sub.SD (.OMEGA.) enabling the use of said simple closed-loop feedback control.
Dependencies are inferred from the claim text.