Abstract:
A method and apparatus are disclosed for reducing transmission of force from a base structure to a supported structure. The method includes mounting a plurality of dampers between the base structure and the supported structure. Each damper includes a single damping element having at least two contact arms affixed to either the base structure or the supported structure. Damping of forces is achieved by each damper in multiple orthogonal directions. The base structure is mounted to a transportation vehicle. The supported structure includes equipment mounted on a floating platform.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Certain embodiments of the present invention relate to reducing forces transmitted from one structure to another. More particularly, certain embodiments of the present invention relate to reducing forces transmitted to a diagnostic medical system during shipment.  
           [0002]    Diagnostic medical systems, such as a diagnostic X-ray system having a large C-arm, are complex, large, heavy, and expensive systems that need to be protected from damage due to shock and vibration during shipment. Units are typically shipped all around the world in vehicles experiencing various road conditions.  
           [0003]    Various packaging systems and methods have been used in shipping medical systems. For example, one method includes mounting the medical system directly onto a wooden base with the chassis of the system elevated and supported on wooden strips. Another method includes sandwiching expanded polyurethane (EP) foam between two layers of plywood and mounting the system on the top layer. The two methods typically do not provide the required isolation from shock and vibration. Other methods include using a high-density polyethylene (HDPE) pallet with the system mounted on the pallet. The tooling cost and per unit production cost of the HDPE pallet often prove to be prohibitive, however.  
           [0004]    Some methods include using relatively sophisticated isolators incorporated into relatively sophisticated configurations. For example, a method described in U.S. Pat. No. 5,808,866 to Porter describes having isolators mounted between a case and a card cage within the case. U.S. Pat. No. 5,149,066 Snaith, et al. describes an isolator having a plurality of arched elements arranged circumferentially about an axis between two structures. U.S. Pat. No. 4,269,400 to Jensen describes an isolator having a plurality of concentrically-arranged, nested, bell-shaped components stacked in parallel about a common axis. U.S. Pat. No. 4,783,038 to Gilbert, et al. describes an isolator with flexural support element pairs being located and offset in planes at acute angles from the horizontal defined by a base means.  
           [0005]    The methods and systems described above tend to be complex, expensive, and/or inadequate for reducing shock and vibration. For example, the isolators described above have multiple damping elements arranged in complex configurations.  
           [0006]    A need exists for a simple damper with a single damping element capable of providing resistance to shock and vibration forces in multiple orthogonal spatial directions. A need also exists for a relatively simple packaging system that uses a plurality of the simple dampers in a simple configuration.  
         SUMMARY OF INVENTION  
         [0007]    An embodiment of the present invention provides for a packaging system for reducing transmission of force from a base platform to a floating platform by employing a plurality of dampers mounted between the base platform and the floating platform. The dampers each comprise a single damping element having at least two contact arms affixed to either the base platform or the floating platform. A plurality of side panels attach to the base platform to enclose equipment that is mounted to the floating platform.  
           [0008]    Apparatus is provided for reducing transmission of force from a base structure to a supported structure. The apparatus comprises a single damping element having at least two contact arms affixed to either the base structure or the supported structure. An affixing base plate is mounted between the damping element and the base structure and an affixing offset plate is mounted between the damping element and the supported structure. The single damping element provides resistance to force in multiple orthogonal spatial directions.  
           [0009]    A method is also provided for reducing transmission of force from a base structure to a supported structure. The method includes mounting a plurality of dampers between the base structure and the supported structure. The dampers each include a single damping element having at least two contact arms affixed to either the base structure or the supported structure. The base structure is mounted to a transportation vehicle. The supported structure includes a diagnostic medical system mounted on a floating platform.  
           [0010]    Certain embodiments of the present invention afford an approach to providing resistance to shock and vibration forces in multiple orthogonal spatial directions using simple dampers each having a single damping element. Certain embodiments also provide for a relatively simple packaging system that uses a plurality of the simple dampers in a simple configuration.  
         BRIEF DESCRIPTION OF DRAWINGS  
         [0011]    [0011]FIG. 1 is an isometric drawing of a damper having a single damping element in accordance with an embodiment of the present invention.  
           [0012]    [0012]FIG. 2 is a top perspective view of a double-X damping element in accordance with an embodiment of the present invention.  
           [0013]    [0013]FIG. 3 illustrates the method of mounting a diagnostic medical system on a floating platform by employing a plurality of the dampers of FIG. 1 in accordance with an embodiment of the present invention.  
           [0014]    [0014]FIGS. 4 a ,  4   b , and  4   c  illustrate several views of a simple configuration of a plurality of the dampers of FIG. 1 arranged between a base platform and a floating platform in accordance with an embodiment of the present invention.  
           [0015]    [0015]FIG. 5 illustrates a packaging system employing a plurality of the dampers of FIG. 1 in accordance with an embodiment of the present invention. 
       
    
    
       [0016]    The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings.  
       DETAILED DESCRIPTION  
       [0017]    [0017]FIG. 1 is an isometric view of a damper  10  showing certain elements of the damper  10  in accordance with one embodiment of the present invention. The damper  10  comprises a base plate  30 , an offset plate  20 , and a single damping element  40 . The single damping element  40  is a single molded piece of rubber having four contact arms  50 ,  60 ,  70 ,  80  forming a three-dimensional X shape in one embodiment of the present invention.  
         [0018]    The two lower contact arms  70  and  80  connect to the base plate  30  and the two upper contact arms  50  and  60  connect to the offset plate  20 . The base plate  30  and the offset plate  20  are made of steel in one embodiment of the present invention. A chemlac bonding process may be used to bond the contact arms  50 - 80  of the rubber damping element  40  to the steel base plate  30  and steel offset plate  20 .  
         [0019]    The base plate  30  and the offset plate  20  each have a through-hole  90  and  100 , respectively. The through-holes  90  and  100  may be used to bolt the damper  10  between a base platform and a floating platform of a packaging system. When mounted between two platforms, the damper  10  reduces transmission of shock and vibration forces in all three orthogonal spatial directions x, y, and z as shown in FIG. 1.  
         [0020]    The rubber contact arms  50 - 80  of the damping element  40  allow the transmission of force to be reduced from the base plate  30  to the offset plate  20  by flexing when force is applied to the base plate from an external source. The X-shape and the rubber material of the damping element  40  provide flexure between the base plate  30  and offset plate  20  in all three spatial directions x, y, and z. The density and thickness of the rubber material of the damping element  40  determine the amount of flexure (resistance to force) provided by a single damper  10 .  
         [0021]    Some typical specifications that are met by the X-damper design are shown in Table 1. The packaging system is designed such that the permissible shock values are limited within that shown in Table 1. Shock values that exceed the specifications are damped by the packaging system. The specifications in Table 1 are representative of the shock forces permissible, as per the GMTC (Global Mechanical Technology Center) standards, by the equipment within the packaging system when on a truck making a 2000 km trip. [t 1 ] 
                                           TABLE 1                           ½sine wave shock pulses (representing a 2000 Km       trip by truck)            Duration   Amplitude   Number of       (Milliseconds)   (m/s 2 ) [g]   Occurrences                    7.5   96.1 [9.8]   324       12.5   39.2 [4.0]   216       17.5   32.4 [3.3]   162       22.5   25.5 [2.6]   135       27.5   16.7 [1.7]   81                  
 
         [0022]    More specifically, the dimensions of one embodiment of the X-shaped damper  10  are set based on shipping a medical diagnostic X-ray system with a large C-arm and meeting the specifications of Table 1. The height of the damper along the z direction, including the base plate  30  and offset plate  20 , is 100 millimeters, the length along the x direction is 110 millimeters, and the width along the y direction is 70 millimeters. The thickness of the steel base plate  30  and offset plate  20  are each 10 millimeters. The rubber material of the single damper is as follows: Specification of the rubber:  
                                             Material: Natural Rubber (No synthetic Variables, Re- Cyclable)                                    Service Temp:   70° C.           Hardness:   80 Shore A           Specific Gravity:   0.83           Tensile Strength:   22 MP                      
 
         [0023]    Other materials may be used for the damping element  40  to achieve various levels of flexure and, therefore, damping for various combinations of density and thickness of the other materials. Materials and dimensions of the damping element may be customized for different equipment having various weights and centers of gravity.  
         [0024]    The fact that the damping element  40  is a single molded piece having a relatively simple shape makes it easy to manufacture and keeps molding and per unit costs down. Of course, other shapes may be configured for the single damping element. For example, FIG. 2 shows a top view of a double-X configuration, having one X crossing orthogonally through another X, manufactured as a single piece. As a result, four contact arms  51 ,  52 ,  61 , and  62  extend from above the center intersection  55  of the double-X and four contact arms (not shown) extend from below the center intersection  55  of the double-X. The double-X configuration may potentially allow more similar damping to be provided along the x and y directions.  
         [0025]    [0025]FIG. 3 illustrates the method of mounting a diagnostic medical system on a floating platform by employing a plurality of the dampers of FIG. 1 in accordance with an embodiment of the present invention. A diagnostic medical system  140  is mounted on top of a floating platform  110 . A plurality of X-shaped dampers  130 - 133  are shown being mounted between the floating platform  110  and the base platform  120 . The dampers are typically bolted to the floating platform and base platform. Various attachment methods may be used to secure the system  140  to the floating platform  110 , such as employing brackets and mounting screws, depending on the configuration of the system  140 .  
         [0026]    [0026]FIGS. 4 a ,  4   b , and  4   c  show various views of a typical damper configuration between a base platform  120  and a floating platform  110 . In this example, eight dampers  130 - 137  are configured in a rectangular, symmetrical pattern. The base plates of the dampers are bolted to the base platform and the offset plates of the dampers are bolted to the floating platform. Any forces that are experienced by the base platform are damped by the dampers and, therefore, the floating platform experiences less force than that experienced by the base platform. As a result, equipment that is mounted to the floating platform is protected from the full force applied to the base platform.  
         [0027]    [0027]FIG. 5 is a three-dimensional view of a packaging system  200 , illustrating how a diagnostic medical system  140  may be packaged using the damper concept. The medical system  140  is mounted to the floating platform  110 . The dampers ( 134 - 137  are shown in this view) are mounted between the floating platform  110  and the base platform  120 . Side panels  150  are mounted around the base platform  120  to enclose the medical system  140  on the floating platform  110 . When the medical system  140  is shipped, the base platform  120  may be mounted to the floor of a shipping vehicle such as a truck. In one embodiment of the present invention, the specifications of Table 1 are met. When the base platform  120  experiences the g-forces expected on a 2000 Km road trip, the diagnostic medical X-ray system  140  with its large C-arm  141  may not experience shock values that exceed the specification of Table 1.  
         [0028]    As a comparison to other methods of damping, a 70 km road test was performed for three designs. The first design uses the expanded polyurethane (EP) foam, the second design uses a HDPE pallet, and the third design uses the X-shaped dampers. During the 70 km road test, the number of force events over 1.5 g experienced by the diagnostic medical system were measured. The EP foam design experienced 16 events, the HDPE design experienced 7 events, and the X-shaped damper design experienced zero events clearly illustrating the superior damping performance of the X-shaped damper design.  
         [0029]    As an alternative, other configurations of dampers may be used depending on the weight and center of gravity of the equipment to be shipped. For example, a circular configuration of dampers may provide better overall damping for equipment where the weight is distributed mostly along the outer perimeter of the equipment. As a further alternative, dampers of differing designs may be employed in a single shipping configuration. For example, in the rectangular configuration of FIG. 4 a , dampers  130 ,  131 ,  134 , and  135  may be X-shaped, and dampers  132 ,  133 ,  136 , and  137  may be double-X shaped. As a result, the damping of forces experienced by the front half of the packaging system (corresponding to dampers  132 ,  133 ,  136 , and  137 ) may be more uniform in the x and y-directions. The damping of forces experienced by the back half of the packaging system (corresponding to dampers  130 ,  131 ,  134 , and  135 ) may be greater in the x-direction and less in the y-direction. Such a configuration may be desirable for certain types of equipment to be shipped.  
         [0030]    In summary, the advantages and features include, among others, providing a simple damper with a single damping element capable of providing resistance to forces in multiple orthogonal spatial directions and a relatively simple packaging system that uses a plurality of the simple dampers in a simple, low cost configuration.  
         [0031]    While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.