Abstract:
A strap clamp secures tubing to an aircraft engine housing. The clamp includes a first portion with a first thickness and a second portion unilaterally extending from the first portion and, with a second thickness. The clamp is flexible and is capable of being formed around the tubing to be secured. The clamp includes a plurality of apertures which receive threaded connectors used to secure the clamp.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to clamps and, more particularly, to strap clamps for securing tubing to an aircraft engine housing. 
     Aircraft engine assemblies require a vast number of pipes and tubes to be connected between components. The tubing and piping is often routed in a space located between an aircraft engine housing and an aircraft engine cowling. Although isolated, this area is still subjected to the high temperatures and high vibrations operated by the aircraft engine. As a result, any clamp assemblies securing tubing in these areas are also subjected to the high temperatures and high vibrations. Typically these clamp assemblies include a bracket assembly anchored to the aircraft engine housing, and a clamp positioned around the tubing to be anchored and attached to the bracket assembly. Because the bracket assembly is typically secured more rigidly to the aircraft engine housing than the clamp is capable of being secured to the bracket, the clamp is subjected to much more stress than the clamp bracket. 
     Clamping systems typically utilize a multi-piece clamp which consists of a flat base member and an upper member welded to the base member. Often the upper member is pre-formed to fit around a specific outer diameter of piping to be anchored. Additionally, often the lower member is also pre-formed to receive a specific outer diameter of piping. A problem with known clamps is that under the high vibrations encountered by the clamping assemblies, the clamps have a tendency to crack and fail due to vibrational fatigue. In particular, those clamps that are pre-formed have a tendency to fail at a location near the apex of the pre-formed bend or at any of the weld locations between the members. In some instances, these failures lead to failure of the base member and eventually to a failure of the particular tubing being secured to the housing. 
     BRIEF SUMMARY OF THE INVENTION 
     In an exemplary embodiment of the invention, a lower strap clamp installs easily, is reliable, and is resilient to vibrations induced by an aircraft engine. 
     The lower strap clamp includes an elongate body having a unitary first portion and a second portion. The first portion has a first thickness and the second portion has a second thickness which is thicker than the first thickness. The elongate body is rigid and remains flat when tubing is anchored to it. The second portion is generally rectangular shaped and extends from the first portion. Since the second portion is unitary with the first portion, no welds are utilized on the strap clamp. The lower strap clamp includes a plurality of apertures which receive threaded connectors used to anchor the strap clamp to a structure. 
     During assembly, a wear sleeve is attached and encircles the tubing being anchored. An upper strap includes a plurality of openings and is bent and formed around the tubing such that the openings on the upper strap clamp align with the apertures on the lower strap clamp. The fasteners pass through the upper strap clamp and extend through the lower clamp bracket to anchor the tubing to the structure. As a result, the risk of the lower clamp failing due to the high vibrations induced by the aircraft engine is minimized. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a strap clamp; 
     FIG. 2 is a plan view of the strap clamp shown in FIG. 1; 
     FIG. 3 is a partial perspective view of a clamping assembly including the strap clamp shown in FIG. 1; and 
     FIG. 4 is a cross-sectional view of the clamping assembly shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a side elevational view of a strap clamp  10  including an elongate body  12  which has a first end  14  and a second end  16 . Elongate body  12  is rigid and is substantially flat. As such, first end  14  and second end  16  are substantially co-planar. In one embodiment, elongate body  12  is machined from a metal such as stainless steel. Alternatively, elongate body is machined from titanium or inconel. Strap clamp  10  is utilized to anchor a tubing (not shown in FIG. 1) to an aircraft engine housing (not shown in FIG.  1 ). In one embodiment, strap clamp  10  is utilized to anchor tubing having an outside diameter of 2.5 inches. 
     Elongate body  12  is unitary and includes a first portion  18  and a second portion  20  extending from first portion  18 . First portion  18  has a first thickness  22 , a length  24 , and a width (not shown in FIG.  1 ). Thickness  22  is substantially constant within first portion  18 . First portion  18  is generally rectangular in shape and includes a top surface  26 , a bottom surface  28 , and a length  29 . Strap clamp  10  is rigid and remains flat when installed. In one embodiment, length  29  is approximately 0.9 inches. Top surface  26  is generally parallel to bottom surface  28 . Second portion  20  has a thickness  30 , a length  32 , and a width (not shown in FIG.  1 ). Second portion thickness  30  is substantially constant within second portion  20  and is thicker than first portion thickness  22 . In one embodiment, elongate body  12  is machined such that first portion thickness  22  is about 0.063 inches and second portion thickness  30  is about 0.125 inches. Second portion  20  is generally rectangular in shape and includes a top surface  34  which is generally parallel to bottom surface  28 . 
     FIG. 2 is a plan view of strap clamp  10 . Strap clamp  10  includes elongate body  12  which is generally rectangular in shape. Elongate body  12  includes first portion  18  and second portion  20 . First portion  18  extends from first end  14  to second end  16  and has a length  24  and a width  42 . In one embodiment, length  24  is approximately 4.118 inches and width  42  is approximately 0.75 inches. First portion  18  also includes an axis of symmetry  50  which extends from first end  14  to second end  16 . An aperture  52  is disposed within first portion  18  adjacent first end  14  and a second aperture  54  is disposed within first portion  18  adjacent second end  16 . Aperture  52  includes a center  56  and second aperture  54  includes a center  58 . First portion  18  includes a second axis of symmetry  60  which is perpendicular to axis of symmetry  50 . Center  56  and center  58  are positioned on axis of symmetry  50 , each a distance  62  from axis of symmetry  60 . In one embodiment distance  62  is approximately 1.739 inches. Apertures  52  and  54  are substantially the same size and in one embodiment each has a diameter of approximately 0.281 inches. 
     Second portion  20  is generally rectangular in shape and includes a first end  70 , a second end  72 , and an axis of symmetry  74  which extends from first end  70  to second end  72 . Second portion  20  includes length  32  and a width  76 . Length  32  is less than length  24  and width  76  is substantially equal to width  42 . In one embodiment, strap clamp  10  is machined such that length  32  is approximately 2.318 inches and width  76  is approximately 0.75 inches. Second portion  20  includes a second axis of symmetry  78  which is perpendicular to axis of symmetry  74 . Strap clamp  10  is machined such that second portion  20  is centered on first portion  18  such that axis of symmetry  74  is co-axial with axis of symmetry  50  and axis of symmetry  78  is co-axial with axis of symmetry  60 . 
     FIG. 3 is a perspective view of a clamping assembly  80  including lower strap clamp  10  and upper strap clamp  82 . Lower strap clamp  10  remains flat and is positioned above a clamp bracket (not shown in FIG. 3) which is anchored to an aircraft engine housing  84 . A plurality of tubing and piping  86  traverse housing  84  leading to various aircraft engine components (not shown). Clamping assembly  80  is utilized to anchor tubing  86  to housing  84 . Upper strap clamp bracket  82  includes a pair of apertures (not shown) which threaded fasteners  88  extend through to secure upper clamp bracket  82  to lower strap clamp  10 . 
     In operation, a wear sleeve  90  is installed around tubing  86  to provide additional wearing protection to tubing  86  in those areas which are anchored to aircraft engine housing  84 . Upper strap clamp  82  is bent to conform to tubing  86  and is form fit over wear sleeve  90  such that the respective openings positioned within upper strap clamp  82  are in alignment with apertures  52  and  54 . Threaded fasteners  88  pass through upper strap clamp  82 , strap clamp  10 , and through the clamp bracket to tighten to housing  84 . 
     FIG. 4 is a cross-sectional view of clamping assembly  80  including lower strap clamp  10  and upper strap clamp  82 . Upper strap clamp  82  is formed around wear sleeve  90  which encircles tubing  86 . Upper strap clamp  82  includes openings (not shown) which receive threaded fasteners  88  (shown in FIG.  3 ). Threaded fasteners  88  extend through the openings in upper strap clamp  82 , through apertures  52  and  54  (shown in FIG. 2) and through openings (not shown) in a clamp bracket  100  to tighten to aircraft housing  84  (shown in FIG.  3 ). When clamping assembly  80  is fully installed, strap clamp  10  remains unbent and substantially flat. 
     The above described unitary strap clamp for securing a tubing to an aircraft engine housing is reliable, easily installed, and is machined. The strap clamp includes no welds which reduces the risk of the clamp failing due to high vibrational fatigue. As such a cost-effective and reliable clamp is provided. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.