Abstract:
A pipe clamp is described in this disclosure. The pipe clamp includes a strap adapted to surround a pipe. The strap includes first and second opposing ends separated by a gap. The clamp also includes a fastener that extends across the gap for tightening or loosening the clamp by narrowing or widening the gap between the first and second opposing ends of the strap. The first opposing end includes at least one projection and the second opposing end defines at least one recess for receiving the projection when the clamp is tightened.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to clamps. More particularly, the present invention relates to clamps for clamping pipes such as vehicle exhaust system pipes.  
         BACKGROUND  
         [0002]    There are many applications where it is desirable to connect two pipes together. One common application is vehicle exhaust systems. In vehicle exhaust systems, two pipes are often connected at a “lap joint.” A “lap joint” is formed by inserting the end of one pipe into the end of another pipe such that the ends overlap one another. A clamp is then placed around the overlapped ends of the pipes. The clamp preferably functions to seal the lap joint and to mechanically connect the two pipes together such that the two pipes are prevented from being pulled apart. Clamps are also used on other types of vehicle exhaust components such as mufflers, catalytic converters, particulate filters, nitric oxide traps, etc.  
           [0003]    Numerous patents exist relating to clamps used for vehicle exhaust systems. Some example patents related to this field include U.S. Pat. No. 4,312,526 to Cassel, U.S. Pat. No. 4,813,720 to Cassel, U.S. Pat. No. 6,116,659 to Wagner, U.S. Pat. No. 4,790,574 to Wagner et al. and U.S. Pat. No. 5,116,083 to Gillingham et al. The clamps disclosed in the above-identified patents are each made of a relatively thin, wide strap of ductile metal and are often referred to as “wide-band clamps.” Other example patents relating to this field include U.S. Pat. No. 6,305,054 to Imes et al., and U.S. Pat. No. 4,558,891 to Wagner et al., both of which are hereby incorporated by reference in their entireties. The &#39;054 patent and the &#39;891 patent disclose clamps of the type often referred to as “narrow-band clamps.” Narrow-band clamps are typically more narrow and substantially thicker than their wide-band counterparts.  
           [0004]    Narrow-band clamps typically include a cylindrical strap having opposed ends separated by a gap. A fastener such as a bolt extends across the gap. To tighten the clamp about a pipe, a nut is threaded on the bolt causing the opposing ends of the strap to be drawn together thereby closing the gap. As the opposing ends of the strap are drawn together, it is sometimes possible for a portion of the pipe being clamped to pucker and become pinched into the gap. If the clamp is being used to seal a lap joint, this puckering and pinching action provides a possible area of leakage. A number of pipe clamps currently on the market from a number of different manufacturers have this problem.  
         SUMMARY  
         [0005]    The present invention relates to a pipe clamp having structure for preventing a pipe from being pinched as the pipe is clamped.  
           [0006]    A variety of advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate several aspects of the invention and together with the description, serve to explain the principles of the invention. A brief description of the drawings is as follows:  
         [0008]    [0008]FIG. 1 is a perspective view of a clamp that is an embodiment of the present invention;  
         [0009]    [0009]FIG. 1A is an enlarged detailed view of a portion of FIG. 1;  
         [0010]    [0010]FIG. 2 is a top view of the clamp of FIG. 1;  
         [0011]    [0011]FIG. 3 is a bottom view of the clamp of FIG. 1;  
         [0012]    [0012]FIG. 4 is a front view of the clamp of FIG. 1;  
         [0013]    [0013]FIG. 5 is a right side view of the clamp of FIG. 1;  
         [0014]    [0014]FIG. 6 is a rear view of the clamp of FIG. 1;  
         [0015]    [0015]FIG. 7 is a right side view of the clamp of FIG. 1;  
         [0016]    [0016]FIG. 8 is a perspective view of a clamp that is another embodiment of the present invention;  
         [0017]    [0017]FIG. 9 is a rear view of the clamp of FIG. 8; and  
         [0018]    [0018]FIG. 10 is a right-side view of the clamp of FIG. 8. 
     
    
       [0019]    While the invention is amenable to various modifications and alternative forms, the specifics thereof have been shown by way of example in the drawings and will be described in detail below. It is to be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the invention as defined by the appended claims.  
       DETAILED DESCRIPTION  
       [0020]    In the following detailed description, references are made to the accompanying drawings that depict various embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made without departing from the scope of the present invention. Further, each of the features disclosed herein can be considered standalone inventive features or features that have inventive aspects when considered in combination with one another.  
         [0021]    FIGS.  1 - 7  illustrate a clamp  20  that is an embodiment of the present invention. The clamp  20  includes a strap  22  (i.e., a band or strip) adapted to surround a pipe. The strap  22  includes first and second opposing ends  24  and  26  (best shown in FIGS. 1 and 2) separated by a gap  28 . A fastener  30  extends across the gap  28 . The fastener  30  functions to tighten or loosen the clamp  20  by narrowing or widening the gap  28  between the first and second opposing ends  24  and  26 . The first and second opposing ends  24  and  26  are preferably configured to prevent a pipe from pinching or puckering into the gap  28  during the clamping process. By preventing the pipe from pinching into the gap  28 , leaks are prevented and an improved seal is provided about the pipe (e.g., at a lap joint).  
         [0022]    Referring to FIGS. 1, 1A and  2 , the structure for preventing a pipe from being pinched in the gap  28  includes circumferential projections configured to intermesh when the clamp  20  is tightened. The first opposing end  24  includes two projections  32  and three recesses  32 ′. The opposing end  26  includes three projections  34  and two recesses  34 ′. When the clamp  20  is tightened, the projections  32  of the first opposing end  24  are received in the recesses  34 ′ of the second opposing end  26 , and the projections  34  of the second opposing end  26  are received in the recesses  32 ′ of the first opposing end  24 . When the projections  32  and  34  are received within their respective recesses  32 ′ and  34 ′, the projections  32  and  34  extend circumferentially past one another. It is noted that when the projections  32  and  34  are received into the recesses  32 ′ and  34 ′, the projections  32  and  34  do not ride over one another so as to form a double wall thickness. Instead, the projections  32  and  34  remain within a cylindrical boundary defined by the wall thickness of the strap  22 .  
         [0023]    It will be appreciated that the projections  32  have shapes that complement the recesses  34 ′ into which they are received, and the projections  34  have shapes that complement the shapes of the recesses  32 ′ into which they are received. As depicted in the drawings, at least some of the projections  32  and  34  have truncated triangular shapes. It will be appreciated that other shapes could also be used.  
         [0024]    The strap  22  is preferably made of a material such as stainless steel or aluminized steel. In one non-limiting embodiment, the strap  22  has a width W (see FIGS. 2 and 3) less than two inches, and a wall thickness T (see FIGS. 4 and 6) in the range of 0.065 to 0.105 inches. Further, straps can be made at different diameters depending of the size of pipe desired to be clamped. In one embodiment, the strap has a diameter D (see FIGS. 4 and 6) in the range of 1¾-7 inches.  
         [0025]    Referring to FIGS. 4 and 6, the fastener  30  of the clamp  20  includes a bolt  40  having a base end  42  and a threaded end  44 . The base end  42  is connected (e.g., welded or secured by another fastening technique) to the first opposing end  24  of the clamp  20 . The threaded end  44  extends across the gap  28  and through a sleeve  46  (i.e., a tunnel) connected to (e.g., welded or fastened by other techniques) to the second opposing end  26 . A nut  48  is threaded on the threaded end  44  of the bolt  40 . By tightening the nut  48 , contact against the sleeve  46  causes the opposing ends  24  and  26  to be drawn together such that the gap  29  closes. When the nut  48  is loosened, the gap  28  widens such that the clamp  20  is loosened. The fastener preferably has the same configuration as the fastener disclosed in U.S. Pat. No. 6,305,054 that was previously incorporated by reference. It will be appreciated that other fastener configurations could also be used to tighten and loosen the clamp.  
         [0026]    The strap  22  is preferably manufactured by punching the desired shape from a length of strap material. The strap  22  is then preferably rolled into a generally cylindrical configuration corresponding to that of a pipe through the use of a conventional roller forming process. With prior art clamps, it has at times proven difficult to form the opposing ends of such clamps with a curvature that precisely matches the curvature of the remainder of the strap. However, it has been determined by the inventors of the present invention that due to the reduction in material caused by providing recesses  32 ′ and  34 ′ at the opposing ends  24  and  26  of the strap  22 , the ends (i.e., the projections  32  and  34 ) can be more easily formed to a curvature that matches the curvature of the remainder of the strap  22 .  
         [0027]    After the strap  22  has been formed into the cylindrical shape as described above, the bolt  40  can be connected to the first opposing end  24  of the strap  22 . Thereafter, the sleeve  46  can be placed over the free end of the bolt  40  and connected to the second opposing end  26  of the strap  22 . Finally, the nut  48  can be threaded on the threaded end  44  of the bolt  40 .  
         [0028]    FIGS.  8 - 10  show a clamp  20 ′ that is another embodiment of the present invention. The clamp  20 ′ includes a sleeve  22 ′ having a reduced diameter portion  60  and an enlarged diameter portion  62 . A radial step  64  provides a diameter change between the reduced diameter portion  60  and the enlarged diameter portion  62 . A similar step is shown in U.S. Pat. No. 6,305,054 that was previously incorporated by reference. It will be appreciated that with the exception of the step  64 , the clamp  20 ′ has the same configuration as the clamp  20  of FIGS.  1 - 7 .  
         [0029]    The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.