Abstract:
A saddle clamp which incorporates internal electrical bonding elements adapted to maintain electrical contact with a clamped tube structure without transferring structural load between the tube and the electrical bonding components. The saddle clamp includes an inner tube contacting surface having at least one surface groove. At least one electrical contact element extends between portions of the inner tube contacting surface. The electrical contact element includes tube contact segment disposed in opposing relation to a portion of the surface groove. The electrical contact element is electrically connected to the mounting bracket to transmit electrical charge from the tube.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This non-provisional application claims the benefit of, and priority from, U.S. Provisional Application 61/256,693 filed Oct. 30, 2009 which is hereby incorporated by reference in its entirety as if fully set forth herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to clamping structures, and more particularly to a saddle clamp adapted to support metal piping or tubing such as a fuel tube or the like in an aircraft or other environment of use. More particularly, the present invention relates to a saddle clamp providing electrical contact between the clamped tubing and a metal support frame or other electrical contact structure. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is known to use plastic saddle clamps to hold piping or tubing in place. One environment of use for such saddle clamps is to support fuel lines or other tubing structures in an aircraft wing. In this environment the saddle clamp is required to accommodate flexing of the fuel line without significantly abrading or otherwise damaging the fuel line. Saddle clamps formed from plastic polymers such as polyamides, polyesters and the like provide these desirable characteristics. 
         [0004]    One characteristic of the polymers used in the prior saddle clamps is that they have low electrical conductivity. Thus, friction may cause electrical charges to build up on the fuel lines during use. To avoid accumulation of such electrical charges it has been common to affix a metal ring about the tube and to run a conductive cable to a bolt or other electrical contact element which is electrically coupled to the frame of the aircraft. As will be appreciated, while this arrangement is quite effective in dissipating electrical charge, it requires a number of additional components and connections thereby increasing assembly time. Moreover, since the conductive cables must be attached by a person, there is a possibility that human error may result in one or more of the cables being grounded improperly or not at all. Further, even when all connections are properly made during initial installation, one or more cables may become disengaged during use or routine maintenance thereby reducing the efficiency of the electrical contact system. 
         [0005]    In light of the above, it would be desirable to provide a clamp suitable to secure a fuel tube or the like to a support frame wherein the clamp provides inherent electrical contact with the tube being carried without the necessity of using a separate charge dissipation element. It would also be desirable for such a clamp to retain the ability to avoid surface abrasion of the tube being carried. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention offers advantages and alternatives over the prior art by providing a saddle clamp which incorporates internal electrical bonding elements adapted to maintain electrical contact with a clamped tube structure without transferring structural load between the tube and the electrical bonding components. Electrical contact connections are thereby maintained without imparting sliding wear to the tubing and the need to use external electrical contact wire connections is reduced or eliminated. Accordingly, such an arrangement substantially reduces complexity while providing enhanced electrical coupling and charge dissipation. 
         [0007]    In accordance with one exemplary aspect, the present invention provides a saddle clamp providing electrical bonding with a tube secured in place within the saddle clamp. The saddle clamp includes a base segment adapted for operative connection to a mounting bracket and an arch segment extending away from the base segment. The arch segment has an inner tube contacting surface. The inner tube contacting surface includes at least one surface groove and at least one window opening extends through the arch segment to define a passageway from the inner tube contacting surface to the exterior of the arch segment. At least one electrical contact element extends between portions of the inner tube contacting surface. The electrical contact element includes a tube contact segment disposed in opposing relation to a portion of the surface groove. The electrical contact element further includes a proximal portion extending through the window opening. The proximal portion is electrically connected to the mounting bracket to transmit electrical charge from the tube. 
         [0008]    Other exemplary aspects and advantages of the invention will become apparent from a detailed description of certain presently preferred embodiments which are shown in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic view illustrating an exemplary saddle clamp in accordance with the present invention in clamping relation to a tube; 
           [0010]      FIG. 2  is a partial breakaway schematic perspective view of an exemplary saddle clamp in accordance with the present invention illustrating internal flexible electrical contact strips of inwardly bowed configuration adapted to contact a surface of a tube (not shown); 
           [0011]      FIG. 3  is an exploded view of the exemplary saddle clamp construction of  FIG. 2  with the flexible contact strips removed; and 
           [0012]      FIG. 4  is a partial breakaway schematic perspective view of a second embodiment of an exemplary saddle clamp in accordance with the present invention incorporating internal flexible electrical contact strips of substantially straight geometry. 
       
    
    
       [0013]    Before the exemplary embodiments of the invention are explained in detail, it is to be understood that the invention is in no way limited in its application or construction to the details and the arrangements of the components set forth in the following description or illustrated in the drawings. Rather, the invention is capable of other embodiments and being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for purposes of description only and should not be regarded as limiting. The use herein of terms such as “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    Exemplary embodiments of the invention will now be described in reference to the drawings, wherein like reference numerals designate like elements in the various views. Referring now to the drawings, in  FIG. 1 , an improved exemplary tube clamping system  10  is shown. As illustrated, the exemplary tube clamping system  10  incorporates a metal bracket  12  which may be attached to a portion of a metal support structure (not shown) by use of connection bolts  14  extending through attachment openings  16  in a manner as will be well known to those of skill in the art. By way of example only, the support structure may be a portion of an aircraft frame although the clamping system  10  may likewise be used in conjunction with virtually any support structure arrangement in numerous alternative environments of use. Without limitation, such alternative environments of use may include petrochemical plants, ground-based fuel storage depots, fuel tanker trucks and the like. 
         [0015]    As shown, the exemplary tube clamping system  10  includes a saddle clamp  20  which is adapted for disposition in supporting wrap-around relation to a metal tube  22  so as to hold the tube firmly in place. By way of example only, and not limitation, the tube  22  may be a fuel line used in the transport of jet fuel from storage tanks to engines in an aircraft. Tubes of aluminum-based alloys may be particularly preferred due to low weight, although other materials may be used if desired. As shown, the exemplary saddle clamp  20  includes an axial passageway  24  ( FIG. 2 ) for receipt and retention of the tube  22 . In the illustrated configuration, lateral feet  28  project radially outwardly away from the axial passageway  24  for disposition in overlying relation to the surface of the bracket  12 . In the illustrated exemplary construction, each of the lateral feet  28  includes one or more acceptance openings for receipt of a metal coupling fastener  30  which extends between the saddle clamp  20  and the underlying bracket  12  to establish both physical and electrical connection between the saddle clamp  20  and the bracket  12 . As will be appreciated, although the coupling fastener is illustrated as a bolt, it is contemplated that virtually any fastener structure that provides electrical and physical connectivity with the bracket  12  may be used. 
         [0016]    As best illustrated through joint reference to  FIGS. 2 and 3 , the saddle clamp  20  may have a two-part design including a base segment  32  and an overlying arch segment  34 . As shown, the base segment  32  includes a platform  35  and a raised support cradle  36  extending upwardly away from the platform  35 . In the illustrated exemplary construction, the raised support cradle  36  includes a pair of lateral arm projections  38  extending upwardly away from the platform  35  with a depressed curved surface  37  running between the arm projections to define the bottom of the axial passageway  24  providing cradling support for the tube  22 . Segments of the platform  35  project outboard from both sides of the support cradle  36  to define lower portions of the lateral feet  28 . Acceptance openings  39  extend through the outboard portions of the base  32  for receipt of the coupling fasteners  30  upon final assembly as will be described further hereinafter. 
         [0017]    The base segment  32  may be formed from any suitable plastic material such as heat stabilized polyamide, polyester, ABS or the like as may be desired. In this regard, Nylon 6/6 may be particularly preferred. By way of example only, and not limitation, the base segment  32  may be formed as a unitary structure by techniques such as injection molding or the like. Of course, other materials of construction and formation techniques may be used if desired. 
         [0018]    The interior of the arch segment  34  is adapted to fit in sliding relation over the support cradle  36  such that outer surfaces of the lateral arm projections  38  are disposed in close, opposing relation to the lower inner surfaces of the arch segment  34 . In this regard, the interior of the arch segment  34  is preferably defined by an upper curved surface forming the top of the axial passageway  24  with substantially straight lower segments for disposition in opposing relation to outer surfaces of the lateral arm projections  38  on the support cradle  36 . 
         [0019]    As illustrated, in the exemplary embodiment the inner surface of the arch segment  34  includes surface grooves  40  disposed on either side of the arch segment  34 . In the illustrated exemplary embodiment, the surface grooves  40  extend circumferentially along the inner surface of the arch segment  34 . The surface grooves  40  may have a substantially flat-bottom construction, although other configurations may be used if desired. The surface grooves  40  may extend along the segment of the inner surface forming the transition between the upper curved surface and the adjacent lower straight surfaces on each side of the arch segment. In this regard, the surface grooves  40  preferably intersect with window openings  44  on either side of the arch segment  34 . The window openings  44  define passageways between the interior and the exterior of the arch segment  34  and are preferably disposed at positions such that they are at least partially covered by outer surfaces of the arm projections  38  of the support cradle  36  when the saddle clamp  20  is in the assembled condition as shown in  FIG. 2 . 
         [0020]    As shown, one or more raised ridges  42  may extend longitudinally along the length of the surface grooves  40 . However, such raised ridges may likewise be eliminated if desired. As will be described further hereinafter, such raised ridges may promote seated acceptance of electrical contact strips within the surface grooves  40  during use. 
         [0021]    As best seen in  FIG. 1 , in the exemplary configuration, the exterior of the arch segment  34  includes a pair of circumferential raised walls  46  which are spaced apart in the axial direction of the clamp to define a circumferential depression  47  between the circumferential raised walls  46 . The circumferential raised walls  46  may have a generally arched configuration with variable height relative to the circumferential depression  47  about the circumference of the arch segment  34 . As shown, the height difference between the raised walls  46  and the circumferential depression  47  may be greatest at the ends of the legs in which the window openings  44  are located thereby providing additional strength in those zones with little or no differential height at the top of the arch. 
         [0022]    In the illustrated exemplary construction, the arch segment  34  includes lateral platform projections  48  which define upper portions of the lateral feet  28 . As shown, acceptance openings  49  extend through the platform projections  48  for alignment with the acceptance openings  39  in the platform  35  of the base segment  32 . Accordingly, the coupling fastener  30  may run through the aligned acceptance openings  39 ,  49  for connection with the bracket  12 . In the illustrated construction, the acceptance openings  49  in the platform projections  48  are oriented at positions between lower portions of the circumferential raised walls  46 . As will be appreciated, in this arrangement the coupling fastener  30  is seated between raised wall segments thereby providing additional protection against damage during use. 
         [0023]    The arch segment  34  may be formed from any suitable plastic material such as heat stabilized polyamide, polyester, ABS or the like as may be desired. In this regard, Nylon 6/6 may be particularly preferred. The material forming the arch segment  34  may be the same as the material forming the base segment  32  although different materials may be used if desired. By way of example only, and not limitation, the arch segment  34  may be formed as a unitary structure by techniques such as injection molding or the like. Of course, other materials of construction and formation techniques may be used if desired. 
         [0024]    As best seen in  FIG. 2 , in the exemplary configuration, one or more conductive electrical contact elements  50  may be disposed at the interior of the arch segment  34  extending in crossing relation between portions of the inner surface surrounding the axial passageway  24 . By way of example only, the electrical contact elements  50  may be metal strips of substantially flat ribbon configuration formed from thin, flexible, spring-like material. Such structures may be formed by techniques such as stamping or other metal forming processes. One exemplary material which may be used for formation of such metal strips is a beryllium-copper alloy with a cadmium coating, although other metallic or non-metallic materials possessing substantial resiliency and electrical conductivity may be used if desired. 
         [0025]    In the illustrated exemplary arrangement the electrical contact elements  50  each include a tube contact segment  52  extending between surfaces at the perimeter of the axial passageway  24 . Each of the electrical contact elements  50  preferably has an effective width which is slightly less than the width of the opposing surface groove  40  such that the electrical contact elements can be received fully within the opposing surface grooves upon the application of force in the radial direction. In the illustrated exemplary construction a longitudinal slot  54  extends along the tube contact segment  52  thereby causing the tube contact segment to have a split construction. The slot  54  may extend partially along the length of the electrical contact element  50  and preferably has a width adequate to accept the raised ridge  42  in the opposing surface groove  40  when the tube contact segment  52  is pressed into the surface groove  40 . 
         [0026]    In the illustrated exemplary configuration, the electrical contact elements  50  each include a distal portion  56  secured in embedded relation within the curved portion of the arch segment  34  of the saddle clamp  20 . By way of example only and not limitation such an embedded relation may be established by press fitting the distal portion  56  into an acceptance slot at the interior of the arch segment. Of course, other techniques for anchoring the electrical contact elements  50  in place may likewise be used. 
         [0027]    As best seen through joint reference to  FIGS. 1 and 2 , each of the electrical contact elements  50  includes a proximal portion  58  which extends between an outer surface of the support cradle  36  and the opposing inner surface of the arch segment  34 . In the illustrated exemplary embodiment, the proximal portion  58  extends through the window opening  44  and is ultimately anchored in place at the surface of the platform projection  48  by the coupling fastener  30  which projects through an eyelet opening positioned in alignment with acceptance openings  39 ,  49 . Thus, when the coupling fastener  30  is inserted through the opening in the proximal portion  58 , and into engagement with the bracket  12 , a continuous electrical connection is established between the electrical contact element  50  and bracket  12  as well as with the frame upon which the bracket is mounted. Thus, static charge may be dissipated from the tube  22  by the contact elements  50 . In this regard, it will be understood that while the exemplary embodiment employs two contact elements  50 , a larger or smaller number may be used as desired. 
         [0028]    In the embodiment illustrated in  FIG. 2 , the tube contact segments  52  of the contact elements  50  are flexed to an inwardly bowed configuration. As will be appreciated, such a configuration causes portions of the tube contact segments to project to a radially inward position within the axial passageway  24 . During use, when the tube  22  is inserted into the axial passageway  24 , the electrical contact elements  50  will contact the outer surface of the tube  22  and the tube contact segments  52  are urged radially outwardly towards the perimeter of the arch segment. As the tube contact segments  52  are pressed outwardly, they conform about the surface of the tube  22  and apply a continuous biasing force against the tube surface. The tube contact segments  52  are ultimately pressed into the opposing surface grooves  40 . However, due to the continuous biasing force of the tube contact segments  52  against the surface of the tube  22 , continuous contact is nonetheless maintained. In this regard, the use of the inwardly bowed configuration may aid in maintaining contact due to the enhanced inward biasing force provided by such a construction. 
         [0029]    As will be appreciated, the spring-like materials forming the electrical contact elements  50  may be substantially harder than the material forming the tube  22  being clamped. However, because the tube contact segments  52  are pressed into the surface grooves  40 , the electrical contact elements  50  are prevented from substantially damaging the tube  22  during use. In this regard, the surface grooves  40  are preferably slightly deeper than the thickness of the corresponding electrical contact elements  50 . Thus, when the tube contact segments  52  are pressed into the surface grooves  40  by the tube  22 , the inner surface of the tube contact segments  52  moves to a position substantially flush with the adjacent inner surfaces of the arch segment  34 . Thus, the tube contact segments  52  do not form a raised abrasive surface. Nonetheless, electrical contact is maintained due to the continuous outward biasing force provided by the tube contact segments  52 . In this condition the structural load continues to be carried between the low friction inner surface of the arch segment  34  and the outer surface of the tube  22 . 
         [0030]    As will be appreciated, maintaining a continuous contact between the tube  22  and the tube contact segments  52  of the electrical contact elements  50  ensures the avoidance of static charge build-up and attendant spark generation. Specifically, any electrical charge is grounded through the connection between the coupling fastener  30  and the underlying bracket  12 . Accordingly, electrical charge is continuously dissipated without the need for any external electrical connection thereby reducing complexity and increasing effectiveness. 
         [0031]      FIG. 4  illustrates an alternative embodiment of the present invention wherein elements corresponding to those previously described are designated by corresponding reference numbers increased by  100 . This embodiment operates in the same manner as previously described but incorporates electrical contact elements  150  having substantially linear tube contact segments  152 . As will be appreciated, in this arrangement the tube contact segments  152  may apply a slightly lower inwardly biasing force and may tend to conform about the tube with slightly less resistance. It is contemplated that such a structure may be particularly beneficial for larger diameter tubes or in environments where low biasing forces against the tube are considered desirable. 
         [0032]    Of course, variations and modifications of the foregoing are within the scope of the present invention. Thus, it is to be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments and equivalents to the extent permitted by the prior art. 
         [0033]    Various features of the invention are set forth in the following claims.