Abstract:
An omnidirectional vibration damping system comprising a pair of dampers of identical make mounted between a carrier rigidly carrying an electronic instrument or like object of protection and a rigid support therefore, the dampers being positioned in axial alignment with each other in positions of symmetry with respect to the center of mass of the object. The carriers have webs laid parallel to a pair of opposed bearing surfaces of the support, each web having formed thereon a hollow boss extending at right angles therefrom. Each damper has a nut extending with clearance through the hollow boss of one carrier and having one end held fast against the bearing surface of the support by receiving a bolt from outside the support. Formed on the other end of the nut is a flange laid parallel to the bearing surface and farther away therefrom than the carrier web. Two damping rings of elastic material and preformed shapes act between nut flange and carrier web, between carrier web and support, between nut flange and support, and between nut and carrier boss, thereby mitigating vibrations both in a plane parallel to the each bearing surface of the support and in a direction at right angles therewith.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to vibration dampers, particularly to those of the class suitable for protection of electronic, electrical, and/or mechanical appliances from external vibrations or shocks that might be applied thereto in multiple directions, among other applications. 
     Vibrations and shocks are potentially detrimental to such electronic instruments as video cameras, video tape recorders, and disk drives, all with precision-made mechanical parts and components built into them. Such devices must therefore be, and indeed have been, protected by vibration dampers of one kind or another, particularly when they are going to be put to use where such vibrations or shocks are imminent or possible. 
     A variety of vibration dampers have been suggested and used for the above and many other purposes. Such conventional devices are all based upon the principle of either springing, viscous damping (utilizing the viscosity of a liquid), friction damping, magnetic damping, or inherent damping (rubber, felt, cork, etc.), or upon combinations of any two or more of the listed types. Dampers for the purposes of this invention are required, among other things, to be compact and inexpensive. No doubt best meeting these requirements are inherent dampers. 
     Conventionally, however, a majority of simple inherent dampers have not been explicitly designed to be omnidirectional, more or less equally effective in multiple directions. The truth of this statement will be acknowledged in light of the fact that the known devices of the class under consideration have had to be installed in many different locations and orientations for protecting an instrument from vibrations in as many different directions. 
     Another weakness of the prior art simple inherent dampers is that they mostly lack inbuilt limit stops for positively arresting the displacement of the object of protection beyond the limits within which the dampers can function as such. Combined use of external limit stops has therefore been necessary to preclude any undue displacement, which might result in damage or destruction, of the object relative to the supporting structure. 
     SUMMARY OF THE INVENTION 
     In consideration of the foregoing state of the art the present invention aims at the provision of a vibration damper of the inherent type that, although so simple and inexpensive in construction, works in multiple directions. 
     Another object of the invention is to incorporate limit stops within the damper of the character defined for restricting the displacement of the object of protection and the deformation of the damper beyond the limit of elasticity. 
     Yet another object of the invention is to protect a precision-made machine or device of any kind from multidirectional vibrations or shocks using a minimum number, typically two, of dampers each attaining the above recited objects. 
     Briefly, the invention may be summarized as an omnidirectional vibration damper to be mounted between an object of protection such as electronic, electrical, and/or mechanical appliances, and a support therefor. The damper comprises a carrier for rigidly carrying an object of protection, the carrier having a first portion laid parallel to a bearing surface of the support, and a second portion extending at right angles with the first portion. Also included are damping means formed from an elastic material and interposed between the support and the carrier. 
     Preferably, the damper according to the invention additionally comprises fastener means rigidly coupled to the support. The fastener mean comprises a first portion laid parallel to the bearing surface of the support and farther away therefrom than the first portion of the carrier, and a second portion extending at right angles with the first portion of the fastener means and concentrically through the second portion of the carrier toward the bearing surface of the support. In a preferred embodiment this second portion of the fastener means takes the form of an internally screw-threaded tube, or nut, in which a bolt is engaged for fastening the fastener means to the support. The damping means acts between the first portions of the carrier and the fastener means, between the first portion of the carrier and the bearing surface of the support, between the first portion of the fastener means and the bearing surface of the support, and between the second portions of the carrier and the fastener means. 
     Thus the damper of this invention can mitigate vibrations both in a plane parallel to the bearing surface of the support, in which extend the first portions of both the carrier and the fastener means, and in a direction at right angles therewith, in which extend the second portions of the carrier and the fastener means. The damper is therefore omnidirectional. 
     It will also be appreciated that, coupled fast to the support and partly concentrically received in the second portion of the carrier, the fastener means coacts with the support to positively limit the displacement of the carrier, and hence of the object of protection, in every possible direction. 
     The present invention also features an onmidirectional vibration damping system comprising only two dampers, each of the construction summarized above, for protecting a desired object. Arranged in axial alignment with each other and in positions of symmetry with respect to the center of mass of the object, the minimal number of dampers can nevertheless effectively protect the object from multidirectional vibrations or shocks. 
    
    
     The above and other objects, features and advantages of this invention and the manner of achieving them will become more apparent, and the invention itself will best be understood, from a study of the following description and attached claims, with reference had to the accompanying drawings showing the preferred embodiments of the invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view, taken through the line A—A in FIG. 2, of an electronic instrument as supported by the vibration damping system according the present invention; 
     FIG. 2 is a plan view of the showing of FIG. 1; 
     FIG. 3 is an exploded perspective view, partly shown broken away, of one of the pair of vibration dampers included in the FIG. 1 damping system; 
     FIG. 4 is an exploded axial section, partly shown broken away, of one of the pair of vibration dampers included in the FIG. 1 damping system; 
     FIG. 5 an axial section through a modified set of damping rings; 
     FIG. 6 is an axial section through another modified set of damping rings; 
     FIG. 7 is an axial section, with parts shown broken away, through another preferred form of vibration damper according to the invention; 
     FIG. 8 is a view similar to FIG. 1 but showing a modified vibration damping system according to the invention; 
     FIG. 9 is also a view similar to FIG. 1 but showing another modified vibration damping system according to the invention; and 
     FIG. 10 is a fragmentary axial section through a modified carrier for use in vibration dampers according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described in detail as applied to the protection of an electronic instrument. In FIGS. 1 and 2 is shown an electronic instrument  1  mounted via a pair of vibration dampers  2  and  3  to a support  4 . The invention is specifically directed to the construction of each vibration damper  2  or  3  as well as to the vibration control system comprising both dampers. Since the two vibration dampers  2  and  3  are identical in construction, only one of them,  2 , will be detailed, it being understood that the same detailed description applies to the other,  3 . 
     The construction of the representative damper  2  will be understood by referring also to FIGS. 3 and 4 which illustrate its component parts on an enlarged scale. The damper  2  comprises, in addition to the support  4  which is shared by both dampers  2  and  3  and which may be considered a part of each damper for the purposes of this invention, a carrier  5  coacting with its counterpart  5  of the other damper  3  for rigidly carrying the electronic instrument  1 , fastener means  8  including a fastener element shown as a screw or bolt  9 , and two damping rings  6  and  7  acting between the support  4  and the carrier  5 , between the support  4  and the fastener means  8 , and between the carrier and the fastener means. 
     Boxlike or tubular in shape and thoroughly enclosing the instrument  1  and the dampers  2  and  3 , the support  4  is made from sheet metal and is sturdy enough to protect the instrument, resisting shocks and pressures that are likely to be exerted thereon in use. All but the two damping rings  6  and  7  of the component parts of the damper  2  are metal made. The damping rings  6  and  7  are molded from any such elastic materials as natural and synthetic rubbers or elastomers typically including silicone in the form of gel or jelly. 
     As revealed by FIG. 1, the carrier  5  is generally U shaped as seen in this figure, including a flat web  10  with a tubular boss  11 , and a pair of flanges  12  bent right-angularly from the web and screwed or otherwise secured to the instrument  1 . The web  10  is laid parallel to the bearing surface  4   a  of the support  4 . As will be noted also from FIGS. 3 and 4, the tubular boss  11  on the web  10  projects right-angularly therefrom in a direction away from the bearing surface  4   a  of the support  4 . This hollow boss  11  may be formed either by stamping of the sheet metal of which the carrier  5  is made or by welding a short tube to the sheet metal. 
     The fastener means  8  with the screw or bolt  9  function to fasten the carrier  5  to the support  4  via the damping rings  6  and  7 . Included are a nut or internally screw-threaded tube  22  with an outside diameter less than the inside diameter of the tubular boss  11  of the carrier  5 , and a flange  23  of disklike shape formed on one end of the nut  22 . The nut  22  extends concentrically and with substantial clearance through the hollow boss  11  of the carrier  5  and, in this particular embodiment of the invention, has one end held against the bearing surface  4   a  of the support  4 . Formed on the other end of the nut  22 , the flange  23  is parallel to the bearing surface  4   a  of the support  4  and farther away therefrom than the web  10  of the carrier  5 . 
     The bolt  9  is engaged in the nut  22  from outside the support  4  through a hole  25  created therein. The nut  22  with the flange  23  is therefore rigidly coupled to the support  4 . 
     FIGS. 3 and 4 also best illustrate the two damping rings  6  and  7 . The first damping ring  6  is a coaxial, one-piece construction of a larger diameter portion  14  and a smaller diameter portion  15 , with a hole  16  extending axially through both portions. Having a surface  18  held against the bearing surface  4   a  of the support  4 , the larger diameter portion  14  of the first damping ring  6  surrounds part of the nut  22  of the fastener means  8  and partly engaged between the bearing surface  4   a  and the web  10  of the carrier  5 . Projecting from the other surface  17  of the larger diameter portion  14 , the smaller diameter portion  15  surrounds part of the nut  22  of the fastener means  8  and surrounded by the hollow boss  11  of the carrier  5 . The diameter of the hole  16  in this first damping ring  6  is approximately equal to the outside diameter of the nut  22 , so that the first damping ring relatively closely fits over the nut. 
     The second damping ring  7  is a simple ring having a pair of opposite surfaces  19  and  20  and a hole  21  extending axially therethrough. Having an inside diameter approximately equal to the outside diameter of the hollow boss  11  of the carrier  5 , the second damping ring  7  fits over that hollow boss and is engaged between the web  10  of the carrier  5  and the flange  23  of the fastener means  8 . 
     Referring specifically to FIG. 4, the axial dimension H 1  of the hollow boss  11  of the carrier  5  is less than the axial dimension H 2  of the smaller diameter portion  15  of the first damping ring  6  and also than the axial dimension H 3  of the second damping ring  7 . The axial dimension H 2  of the smaller diameter portion  15  of the first damping ring is approximately equal to the axial dimension H 3  of the second damping ring  7  plus the thickness of the web  10  of the carrier  5 . Thus, as will be seen by referring back to FIG. 1, the hollow boss  11  of the carrier  5  is spaced from the flange  23  of the fastener means  8 . 
     Before the damper  2  is assembled and mounted in position as shown in FIG. 1, the axial dimension H 4  of the nut  22  of the fastener means  8  is less than the axial dimension H 5  of the first damping ring  6 . The first damping ring  6  is compressed, however, to the same dimension as the nut  22  when the bolt  9  is fully driven into the nut as in FIG.  1 . 
     In assembling and mounting the damper  2 , the carrier  5  may be fastened to the electronic instrument  1  either before or after the two damping rings  6  and  7  are mounted to the carrier. The smaller diameter portion  15  of the first damping ring  6  may be inserted in the hollow boss  11  of the carrier  5 , which has been, or is not yet, fastened to the instrument  1 , until the surface  17  of the larger diameter portion  14  hits the web  10  of the carrier. Then the second damping ring  7  may be fitted over the carrier boss  11  so that the surface  20  of the ring rests against the web  10 . Then the nut  22  of the fastener means  8  may be inserted in the hole  16  in the first damping ring  6  from its smaller diameter portion  15  until the flange  23  on the nut comes into abutment against the ends of both first  6  and second  7  damping rings. 
     Next comes the step of mounting the damper  2  to the support  4 , it being understood that the instrument  1  has already been attached to the carrier  5 . With the surface  18  of the first damping ring  6  held against the bearing surface  4   a  of the support  4 , the bolt  9  may be driven into the nut  22  via the hole  25  in the support until the nut  22  comes to butt on the bearing surface  4   a.  Although greater in axial dimension than the nut  22  as aforesaid, the first damping ring  6  will be compressed as the bolt  9  is driven into the nut and become equal in axial dimension to the nut when this nut comes into abutment against the bearing surface  4   a  of the support  4 . 
     Now has been completed the assemblage and mounting of the damper  2 . The other damper  3  may be assembled and mounted in place in a like manner. The completion of the mounting of both dampers  2  and  3  is tantamount to the elastic, vibration-proof mounting of the instrument  1  to the support  4 . 
     A reconsideration of FIG. 1 will show that the web  10  of the carrier  5  is caught between the larger diameter portion  14  of the first damping ring  6  and the second damping ring  7 . Since the hollow boss  11  of the carrier  5  is normally spaced from the flange  23  of the fastener means  8 , the damping rings  6  and  7  are capable of elastic deformation in both directions along the z-axis indicated in FIG.  1 . 
     The hollow boss  11  of the carrier  5 , on the other hand, is sandwiched between the smaller diameter portion  15  of the first damping ring  6  and the second damping ring  7 . These damping rings are therefore elastically deformable in any direction in a plane containing the x- and y-axes in FIG.  1 . Thus the damper  2  can protect the instrument  1  from triaxial vibrations and shocks. 
     FIG. 1 further indicates that only a minimal number, two, of dampers  2  and  3  are used for protecting the instrument  1  by virtue of their omnidirectional damping capabilities. For most effectively guarding the instrument  1  the two dampers  2  and  3  are arranged in axial alignment with each other in positions on symmetry along a notional line  27  extending through the center of mass  26  of the instrument  1 . Being effective in both vertical and horizontal directions, the two aligned dampers  2  and  3  will favorably protect the instrument  1  from vibrations that might be applied thereto in any direction. 
     The following is a list of advantages gained by the specific embodiment of the invention disclosed above: 
     1. The damper  2 , though so simple and inexpensive in construction, is thoroughly tridimensional in its effectiveness. 
     2. Rigidly coupled to the support  4 , the fastener means  8  function as stops for limiting the displacement, and preventing the destruction, of the damping rings  6  and  7 . 
     3. The carrier  5 , damping rings  6  and  7 , and fastener means  8  are all concentric with one another, so that they can be readily assembled by interfitting them sequentially. 
     4. The component parts of the damper  2  are inseparably coupled together, and the damper mounted in position between carrier and support, simply as the bolt is driven into the flanged nut. 
     5. The degree of elasticity of the damper in any of the x-, y- and z-axes is adjustable by changing the pertinent dimensions of the damping rings  6  and  7 . 
     6. Only two dampers  2  and  3  are needed to protect the instrument  1  from omnidirectional vibrations. 
     Second Form 
     A second preferred form of vibration damper according to the invention features a modified first damping ring  6   a , FIG. 5, which is for use in the first disclosed damper  2  or  3  in substitution for the first disclosed first damping ring  6 . The modified first damping ring  6   a  is divided into a larger diameter member  14   a  and a smaller diameter member  15   a , both having holes  16   a  and  16   b  of the same diameter. The two ring members  14   a  and  15   a  can be molded from the same material or from different materials. 
     In assembling and mounting the damper incorporating the modified first damping ring  6   a , the smaller diameter ring member  15   a  may first be inserted in the hole  13 , FIG. 4, in the web  10  of the carrier  5 . Then the second damping ring  7  may be fitted over the hollow boss  11  of the carrier web  10 . Then the nut  22  of the fastener means  8  may be inserted in and through the hole  16   b  in the smaller diameter ring member  15   a  and then in the hole  16   a  in the larger diameter ring member  14   a.  The rest of the procedure is as set forth above in connection with the first embodiment of the invention. 
     The damper with the divided first damping ring  6   a  is just as effective as that including the integral first damping ring  6 . The fabrication of two simple ring members of different diameters is nevertheless easier than that of the integral ring of two different diameter portions. As required or desired, moreover, different materials with different elasticities may be employed for the two ring members  14   a  and  15   a  in each specific application of the invention. 
     Third Form 
     In FIG. 6 is shown another modified first damping ring  6   b , also for use in the first disclosed damper  2  or  3  in place of the first damping ring  6 . This second modification is similar to the first modified damping ring  6   a  in that the ring is divided into a larger diameter member  14   b  and a smaller diameter member  15   b , but differs therefrom in that the larger diameter member  14   b  has a hole  16   a  large enough to receive the smaller diameter member  15   b.  This smaller diameter member  15   b  has a hole  16   c  extending axially therethrough just like the hole  16  in the FIG. 4 damping ring  6 . The axial dimension H 5  of the smaller diameter member  15   b  is the same as that of the damping ring  6 , and the dimension H 2  of that part of the smaller diameter member  15   b  which projects from the larger diameter member  14   b  is the same as that of the smaller diameter portion  15  of the damping ring  6 . 
     This second modified damping ring  6   b  gains the same advantages as does the FIG. 5 damping ring  6   a.    
     Fourth Form 
     FIG. 7 represents a further modified vibration damper  2   a  according to the invention, featuring a one-piece construction  6   c  of what are shown in FIGS. 1-4 embodiment as the first  6  and second  7  damping rings. Thus the integral damping ring  6   c  is shaped like the combination of these first disclosed damping rings  6  and  7 , that is, a cylinder having a hole  16   c′  extending axially therethrough, the hole being equivalent to the hole  16  in the first damping ring  6 . The nut  22  is received in the hole  16   c′.    
     It will be also noted from FIG. 7 that the integral damping ring  6   c  is molded in place on the carrier  5 , enveloping its hollow boss  11  and the neighboring part of the web  10 . This is possible by the familiar insert molding method. 
     In FIG. 7 is further shown an electronic circuit board  30  mounted on the web  10  of the carrier  5 . This showing represents an additional possible use of the invention. 
     Fifth Form 
     In each of the dampers  2   b  and  3   b  shown in FIG. 8 the hollow boss  11  of the carrier  5  extends from the web  10  toward the bearing surface  4   a  of the support  4 , instead of away from the bearing surface as in all the foregoing embodiments. In conformity with this modified carrier configuration the two damping rings  6  and  7  are reversed in position. Thus the first damping ring  6  has its larger diameter portion  14  surrounding part of the nut  22  of the fastener means  8  and partly engaged between the web  10  of the carrier  5  and the flange  23  of the fastener means  8 , and its smaller diameter portion  15  surrounding the rest of the nut  22  and surrounded by the hollow boss  11  of the carrier  5 . The second damping ring  7  surrounds the hollow boss  11  of the carrier  5  and is engaged between the bearing surface  4   a  of the support  4  and the web  10  of the carrier  5 . 
     This embodiments provides the advantage that the first damping ring  6  can be molded in one piece with the fastener means  8  for greater use of assemblage. 
     Sixth Form 
     The dampers  2   c  and  3   c  seen in FIG. 9 have each damping rings  6 ′ and  7 ′ of greater axial dimensions, relative to the nut  22  of the fastener means  8 , than their counterparts  6  and  7  of all the previous embodiments. Consequently, the nut  22  of the fastener means  8  is spaced from the bearing surface  4   a  of the support  4 , unlike the foregoing embodiments in which the nut contacts the bearing surface. 
     The provision of the spacing between support  4  and nut  22  is preferable in cases where the damping rings  6 ′ and  7 ′ in use are not sufficiently elastic for omnidirectionally alleviating vibrations by making them immovable relative to each other. The provision of a similar spacing is also possible in the embodiments of FIGS. 7 and 8. 
     Seventh Form 
     FIG. 10 fragmentarily illustrates a modified carrier  5   a  having a hollow boss  11   a  extending toward the bearing surface, not shown here, of the support in addition to that  11  extending away therefrom. The boss  11   a  should be spaced from the bearing surface like that of FIG.  8 . The modified carrier  5   a  may be employed in combination with one damping ring with an outside diameter to fit in the hollow bosses  11  and  11   a  and two other damping rings with an inside diameter to fit over these hollow bosses. 
     Possible Modifications 
     Notwithstanding the foregoing detailed disclosure it is not desired that the present invention be limited by the exact showing of the drawings or the description thereof. The following, then, is a brief list of possible modifications or alterations of the illustrated embodiments: 
     1. Only one or three or more dampers, instead of two as in the foregoing embodiments, may be employed for supporting a desired object of protection. 
     2. The hollow boss  11  on the web  10  of the carrier  5 , which is shown as a tube in all the illustrated embodiments, could take other forms such as, for instance, a plurality of fingers of annular or similar arrangement defining a space for the passage of the smaller diameter portion  15  of the first damping ring  6 , or an equivalent part of the other first damping rings  6   a ,  6   b  and  6   c  disclosed. 
     3. The unitary support  5  may be divided into two or more discrete members each having an end portion bent right-angularly to serve as the noted fingers of annular or like arrangement. 
     All these and other changes of the illustrated embodiments are intended in this disclosure. It is therefore appropriate that the invention be construed broadly and in a manner consistent with the fair meaning or proper scope of the annexed claims.