Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
1999-02-05
2001-02-13
Butler, Douglas C. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140150
Reexamination Certificate
active
06186485
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vibration insulating apparatus and a vibration insulating method reducing vibration transmitted to a vehicle or the like which is a mounting body from a power unit or the like which is a vibration source by use of an active mounting characteristic, and more particularly, to a vibration insulating apparatus and a vibration insulating method which are conformably used with a vibration isolation mounting device positioned between the vibration source and the mounting body and having a fluid chamber defined by an elastic support so as to change a volume of the fluid chamber by displacing a resiliently supported movable member, so that the change of the volume is applied to a so-called expanding spring of the elastic support.
Japanese Patent Application Laid-open No. H8-109946 discloses an apparatus having an active vibration control function, disposed between a vibration source and a mounting body and capable of reducing the vibration transmitted from the vibration source utilizing its active mounting characteristic.
SUMMARY OF THE INVENTION
According to analysis by the present inventor and the like, the apparatus disclosed in Japanese Patent Application Laid-open No. H8-109946 has a mass/spring system comprising a mass portion which is a movable member constituting a portion of a partition wall of a fluid chamber accommodating fluid, and a spring portion which is a resilient member supporting the movable member, and vibration force is applied to the movable member, thereby exhibiting its active mounting characteristic.
Such a mass/spring system exhibits a resonance phenomenon due to vibration generated in the vibration source and transmitted from the vibration source when the vibration force is applied in such a manner that the active mounting characteristic is to be exhibited, and it is considered that the active mounting characteristic may be influenced.
Therefore, it is preferable to mass of the movable member and a spring constant of the resilient member are set such that the resonance frequency of the mass/spring system becomes higher by one digit than the upper limit frequency in a resonance frequency band of the vibration generated in the vibration source and transmitted therefrom. Further, it is preferable that a driving signal to be applied to an electromagnetic actuator which is a concrete vibration force source is applied through a low-pass filter which brings the resonance frequency of the mass/spring system into a cutoff frequency.
However, according to research by the present inventor, also in such an apparatus having an active vibration control function including a mass/spring system to which the vibration force is applied, even if the above described setting and processing of the driving signal are conducted, the resonance phenomenon is generated when the active mounting characteristic should be exhibited in some cases.
Thereupon, the present inventor repeated further analyses and researches, and have found out that the main reason of the resonance phenomenon is that an applied load which should be mounted by the apparatus acts on the mass/spring system through the fluid in the fluid chamber or the mounting resilient body, and that the resonance frequency of the mass/spring system is largely changed from the initially set value to low frequency side and as a result, the resonance frequency of the mass/spring system is included in the frequency band of the vibration generated in the vibration source and transmitted therefrom.
The present invention has been achieved based on the above described new technical viewpoint, and it is an object of the present invention to provide a vibration insulating apparatus and a vibration insulating method which are conformably used with such a vibration insulating mount and effectively suppress the resonance phenomenon of the mass/spring system due to the vibration transmitted from the vibration source so that its active mounting characteristic can reliably be exhibited.
To achieve the above object, a vibration insulating apparatus according to the present invention is preferably applied to a vibration insulating mount disposed between a vibrating body and a mounting body. Here, the vibration insulating mount comprises a fluid chamber filled with fluid, an elastic support partly defining the fluid chamber, a movable member partly defining the fluid chamber, a resilient member resiliently supporting the movable member, and an actuator generating displacing force for the movable member according to a drive signal so as to change volume of the fluid chamber. Also, the vibration insulating apparatus according to the present invention includes a reference signal generating device detecting a vibrating condition of the vibrating body and outputting a reference signal indicative of the vibrating condition, a residual vibration signal generating device detecting a residual vibration of the mounting body and outputting a residual vibration signal indicative of the residual vibration, and a driving control device calculating the driving signal output to the actuator according to the reference signal and the residual signal so as to reduce vibration transmitted from the vibrating body to the mounting body. Thereupon, the driving control device outputs the driving signal to the actuator by use of low-pass filter processing and a cutoff frequency used in the low-pass filter processing is set in accordance with a state of a load applied to the vibration insulating mount.
In other words, a vibration insulating apparatus of the present invention comprises isolation mounting means disposed between a vibrating body and a mounting body, control means applying a driving signal generated by use of low-pass filter processing to a mass/spring system of the vibration isolation mounting means so as to control the active mounting characteristic of the vibration isolation mounting means, and load detecting means detecting a state of a load applied to the vibration isolation mounting means. Here, a cutoff frequency used in the low-pass filter processing is set in accordance with the state of the load detected by the load detecting means.
On the other hand, a vibration insulating method of the present invention comprises the following steps. That is, The method generates a driving signal by use of low-pass filter processing so as to vibrate a mass/spring system of a vibration isolation mounting device disposed between a vibrating body and a mounting body, applies the driving signal to the mass/spring system of the vibration isolation mounting device to vibrate the mass/spring system, and detects a state of a load applied to the vibration isolation mounting device. Here, a cutoff frequency used in the low-pass filter processing is set in accordance with the detected state of the load.
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Butler Douglas C.
Foley & Lardner
Kramer Devon
Nissan Motor Co,. Ltd.
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