Hybrid passive and active vibration isolator architecture

Details Hybrid passive and active vibration isolator architecture Hybrid passive and active vibration isolator architecture

1999-10-22

2002-03-12

Schwartz, Christopher P. (Department: 3613)

Spring devices

Resilient shock or vibration absorber

Including energy absorbing means or feature

Reexamination Certificate

active

06354576

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to vibration isolators and more particularly to small easily installed retrofittable modular vibration isolators for active and passive use in a variety of applications such as may be found in satellite payloads for laser cross-link systems, precision pointing systems, submarine decking, launch isolation for precision equipment, E-beam lithography, micro lithography and other optical payloads.
2. Description of the Prior Art
Many passive and active vibration isolation devices exist in the art. Active systems using magneto restrictive or piezoelectric actuators work well for low frequency response, precision pointing and active force cancellation, but are usually more complicated than passive systems. Passive systems work well for solving many high frequency problems but have some material limits. Examples of passive systems include a bellows with fluid in it such as shown in L. P. Davis U.S. Pat. No. 4,760,996 entitled “Damper and Isolation,” issued on Aug. 2, 1988, in L. P. Davis U.S. Pat. No. 5,332,070 entitled “Three Parameter Viscous Damper and Isolator,” issued on Jul. 26, 1994, and in L. P. Davis U.S. Pat. No. 5,219,051 entitled “Folded Viscous Damper,” issued Jun. 15, 1993 (sometimes referred to herein as a “Folded D Strut”) all of which are assigned to the assignee of the present invention. These devices perform vibration isolation remarkably well in a variety of applications including those in space. Other isolators such as large rubber materials or shape memory alloys, SMAs, such as nickel titanium based materials, are sometimes used in situations where large shock vibrations are expected such as during satellite launchings. Most of the prior art vibration isolators are designed to be part of the members to be isolated or are installed at least at the time of assembly of the two members. As such, they are specifically designed for the particular parameters to be encountered. The size of the isolator and ease of mounting it are seldom problems, so great latitude has been permitted in the designs.
When dealing with some situations, however, vibration isolation is an afterthought since the desirability of using vibration isolators is not discovered until after the equipment is constructed and assembled and undesirable vibrations are discovered in use. Likewise, particularly in space applications, the space allotted for vibration isolation is extremely limited, and the retrofitting of vibration isolators into an already existing assembly becomes quite difficult.
BRIEF DESCRIPTION OF THE INVENTION
The present invention combines several types of vibration isolators into a single unitary structure to handle a wide variety of conditions and is of small overall dimensions for use in crowded environments and is further capable of being easily mounted in a large number of already existing environments. More particularly, a small, preferably cubic, structure of as little as one inch in each dimension is employed constructed of 1) a passive isolator, preferably a Folded D Strut such as shown in the above mentioned U.S. Pat. No. 5,219,051 of Lawrence P. Davis, 2) an active isolator preferably one employing a piezoelectric actuator with closed loop control, and, if needed, 3) a shock vibration isolator preferably one using a deformable material, or SMA. One end of the active system is connected to the member which may vibrate, and one end of the passive system is connected to the payload to be isolated. The other ends of the active and passive systems are connected to an interstage mass. One corner of the cube contains a threaded mounting hole for attachment to a first of the two members to be isolated and the opposite corner of the cube is mounted on the second of the two members to be isolated. The third shock-type vibration isolator, if used, may be a removable bumper, or preferably, a “shape memory alloy” material, SMA, may also be included in parallel with the other two isolators in the event that a shock, such as by satellite launching, is to be encountered. The advantages of such a system include being sized for retrofitting light to heavy payloads and the ability to be placed directly in the load path of an existing or new payload and tuned to meet the isolation requirements of the system. It may be used in the purely passive mode, in the passive/active mode or in the active mode. When used in the active or passive/active modes, each individual isolator local controller can be linked to another isolator local controller or to a central control system so as to perform global control by receiving feedback signals from each of the local controllers and providing an augmentation signal to adjust the individual responses. In addition, the isolator can provide shock load protection so that it can be used during launch and in orbit.


REFERENCES:
patent: 4760996 (1988-08-01), Davis
patent: 5052529 (1991-10-01), Sutcliffe et al.
patent: 5219051 (1993-06-01), Davis
patent: 5332070 (1994-07-01), Davis et al.
patent: 5333455 (1994-08-01), Yoshioka
patent: 5551650 (1996-09-01), Southward et al.
patent: 5660255 (1997-08-01), Schubert et al.
patent: 5730429 (1998-03-01), Ivers et al.
patent: 6022005 (2000-02-01), Gran et al.

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