Abstract:
A band clamp comprising a sleeve and a tightening mechanism that includes at least one fastener, such as a nut and bolt, as well as a reaction member which is constructed of a single piece of sheet metal. The reaction member is disposed between the end flanges of the clamp sleeve and can be shaped such that it is forcibly pressed into engagement with the underlying pipe when the clamp is tightened. The reaction member can be a separate component retained between the flanges by engagement of end portions of the reaction member with retainer ears on the flanges. Alternatively, the end flanges and reaction member can all be unitary portions of the clamp sleeve such that the complete band clamp, except for the bolt and nut, is comprised of a unitary piece of sheet metal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the priority of U.S. Provisional Patent Application No. 60/452,404, filed Mar. 6, 2003, the entire contents of which are hereby incorporated by reference. 
   FIELD OF THE INVENTION 
   This invention relates to band clamps and more particularly, it relates to band clamps for pipes and hoses. 
   BACKGROUND OF THE INVENTION 
   In the manufacture of vehicles such as cars, trucks, motorcycles, snowmobiles and the like, band clamps are commonly used for joining pipe ends together in the engine exhaust system. Also, band clamps are commonly used for joining hoses, such as hydraulic hoses, to hose fittings. In these applications, it can be important for the pipe joints to provide a good fluid seal to prevent leakage. It can also be important for the joint to exhibit a high degree of mechanical strength for withstanding road shock and vibration without loosening and without impairment of the sealing properties of the pipe joint. Band clamps for such vehicle exhaust systems are commonly used for making both lap joints, with the pipe ends overlapping each other, or butt joints, with the pipe ends abutting each other. In such applications, the clamp tightening mechanism must be capable of exerting a stretching force on the clamp sleeve so that it produces a radially-directed compressive force between engaging surfaces of the band and the underlying pipe ends whereby the pipe joint may exhibit good mechanical strength and sealing properties. 
   Band clamps are already known in the prior art which have the capabilities described above. Such clamps are exemplified by Cassel et al. U.S. Pat. No. 4,629,226 granted Dec. 16, 1986 and Cassel U.S. Pat. No. 4,312,526 granted Jan. 26, 1982, and the entire contents of these two patents are hereby incorporated by reference. Apart from these two Cassel patents, the Thompson U.S. Pat. No. 4,364,588, granted Dec. 21, 1982 and Calmettes et al. U.S. Pat. No. 5,131,698, granted Jul. 21, 1992, disclose band clamp designs using alternative reaction member designs. While the clamps of the aforementioned patents may be suitable for their intended applications, it is desirable to provide a band clamp having a clamp tightening mechanism which can be manufactured in high volume at lower cost than at least some of these prior art designs. 
   SUMMARY OF THE INVENTION 
   In accordance with this invention, a band clamp is provided with a clamp band, or sleeve, and with a tightening mechanism which is capable of exerting a large stretching force on the clamp sleeve and which can be manufactured in high volume at low cost. The tightening mechanism includes at least one fastener, such as a nut and bolt, as well as a reaction member which is constructed of a single piece of sheet metal. The reaction member is disposed between the end flanges of the clamp sleeve and can be shaped such that it is forcibly pressed into engagement with the underlying pipe when the clamp is tightened. The end flanges and reaction member can be unitary portions of the clamp sleeve such that the complete band clamp, except for the bolt and nut, is comprised of a unitary piece of sheet metal. 
   A complete understanding of this invention may be obtained from the detailed description that follows taken with the accompanying drawings. 

   
     DESCRIPTION OF THE DRAWINGS 
     Preferred exemplary embodiments of the invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein: 
       FIG. 1  is a perspective view of a first embodiment of the band clamp of this invention; 
       FIG. 2  is another perspective view of the first embodiment of the band clamp of this invention; 
       FIG. 3  is another perspective view of the first embodiment without the bolt and nut; 
       FIG. 4  is an end elevation view of a second embodiment of the band clamp of this invention; 
       FIG. 5  is an end elevation view of a third embodiment of the band clamp of this invention; and 
       FIG. 6  is a side elevation view of this band clamp of  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings, the invention is shown in three different embodiments of a band clamp especially adapted for use in coupling pipe ends together to form a pipe joint in vehicle exhaust systems. In exhaust system applications, the band clamp is preferably made of steel. In the illustrative embodiments of the invention, the invention is implemented in a band clamp with a single bolt in the tightening mechanism in the manner shown in the above-cited Cassel et al. U.S. Pat. No. 4,629,226. The invention can also be implemented with a tightening mechanism having two bolts as disclosed in the above-cited Cassel U.S. Pat. No. 4,312,526. It will be appreciated as the description proceeds, that the invention is useful in many different applications and may be implemented in many other embodiments. 
   In the drawings, the band clamp of this invention is shown in its un-installed condition in readiness for placement over ends of two pipes (not shown) which are to be coupled together by the band clamp to make a pipe joint. In this usage, the band clamp constitutes a pipe coupling for making a pipe joint. The band clamp of this invention is of the open sleeve type with a roundish sector which terminates in oppositely disposed end flanges which define a radially extending sector, as disclosed in the aforementioned Cassel U.S. Pat. No. 4,312,526. The two pipes which are to be coupled together may be of substantially the same diameter and disposed within the band clamp with opposed ends in abutting relation to form a butt joint. For use in a butt joint, the clamp sleeve is preferably of uniform diameter. Alternatively, the two pipes may have different diameters at the adjoining ends with one inside the other in a telescoping relation to form a lap joint. For a lap joint, the clamp sleeve may be preformed in the roundish sector to provide end bands of different diameters to accommodate the different outside diameters of the pipes. The clamp sleeve may be preformed by the method disclosed in Cassel U.S. Pat. No. 4,261,600 granted Apr. 14, 1981. 
   First Embodiment of this Invention 
   The first embodiment of the invention will be described with reference to  FIGS. 1 ,  2  and  3 . The band clamp  10  comprises, in general, a clamp band  12  and a clamp tightening mechanism  14 . A clamp sleeve  16  is formed as a roundish-shaped sector and has open ends terminating in radially-extending end flanges  18  which comprise part of the clamp tightening mechanism  14 . The clamp band  12  and clamp tightening mechanism  14  will be described in detail below. 
   The clamp band  12  comprises an open sleeve  16  of roundish-shape which terminates in opposite end flanges  18  which extend radially from the sleeve and are unitary therewith. As mentioned above, the end flanges comprise parts of the clamp tightening mechanism. As can be seen in  FIG. 3 , the sleeve can be opened to place the clamp sleeve around the pipe ends for either a lap joint or a butt joint. Each end flange  18  terminates at its outer end in a pair of circumferentially extending, spaced-apart retainer ears  22  which extend toward the other end flange. On each end flange, the pair of retainer ears define a keeper notch  24  therebetween. 
   The clamp tightening mechanism  14  comprises the pair of end flanges  18 , a reaction member  26 , a bolt  28  and a nut  32 . The reaction member has a V-shaped body  34  with a rounded base  36  and outwardly extending legs  38  each having transversely extending hanger ears  42  directed away from each other. The hanger ears  42  are disposed in respective notches  24  to support the reaction member  26  between the end flanges  18  with the inner extremity of the base  36  of the body  34  located at the inside diameter of the sleeve  16 . The end flanges  18  and the legs  38  of the reaction member  26  are provided with aligned bolt holes  44  for receiving the shank of the bolt  28  with the bolt head seated on the outside surface of one end flange  18  and the nut  32  seated against the outside surface of the other end flange  18 . 
   Before the band clamp  10  is installed, the parts may be loosely assembled as shown in  FIG. 3  or the parts may be unassembled. In some applications, the pipe ends may be inserted axially into the band clamp in its loosely assembled state. In other applications where the pipe ends are already telescoped together or abutted with each other, it will be necessary to pass the open clamp sleeve laterally over the pipes and then assemble the clamp parts. With the loosely assembled band clamp  10  in place, the nut  32  is tightened on the bolt  28  to stretch the clamp sleeve  12  around the pipes. As the nut is tightened, the end flanges  18  are drawn toward each other and the V-shaped reaction member  34  is progressively deformed to a narrower width. Also during tightening, the end flanges  18  are pulled inwardly and the retainer ears  22  force the base  36  of the reaction member inwardly toward a central region of the band  12  and into engagement with the outer surface of the adjacent pipe. At some point during tightening, the sleeve  16  of the clamp band  12  and the base of the reaction member  26  are snugly seated against the pipe but, at that point, only a small tensile stress is developed in the sleeve. In order to achieve a high degree of mechanical strength (pull-apart strength) and a good gas-tight seal in the pipe joint, it is necessary to tighten the nut sufficiently to stretch the sleeve  16  so as to develop the desired degree of tensile stress. Accordingly, the clamp tightening mechanism  14 , including the end flanges  18  and reaction member  26  must exhibit sufficient structural strength to transmit the necessary forces from the bolt  28  to the sleeve  16 . The V-shaped structure of the body  34  of the reaction member  26  provides leverage with good mechanical advantage for transmitting the forces for stretching the sleeve  16 . Further, the V-shaped structure has the advantage of requiring a minimum amount of material for the reaction member  26  and can be fabricated from sheet steel by a stamping operation. This component will transfer clamp load under the fastening mechanism to provide a 360 degree seal and prevent wrinkling of the pipe under the fastening mechanism, which will prevent leakage. It is desirable to use a large area bolt head and a large area nut, preferably with a diameter or rectangular dimension substantially as large as the radial length of the end flanges  18  to minimize the bending stresses in the end flanges. Thus the structural configuration of the clamp tightening mechanism  14  is highly advantageous in that it can provide a large value of tensile stress in the sleeve  16  with the end flanges and the reaction member being made of relatively thin steel. 
   Second Embodiment of the Invention 
   The second embodiment of the invention is shown in  FIG. 4 . The band clamp  10 ′ of this embodiment has a clamp tightening mechanism  14 ′ which is of different structure from that of the first embodiment. In the description of the second embodiment, those parts which are similar to but not identical to corresponding parts of the first embodiment are designated by the same reference numbers but with the addition of a prime symbol, e.g.  10 ′. 
   Referring now to  FIG. 4 , the clamp tightening mechanism  14 ′ comprises a pair of end flanges  18 ′, a reaction member  26 ′ and, like the first embodiment, a bolt and nut (not shown). Each end flange  18 ′ terminates at its outer end in a retainer ear  22 ′ which is coextensive with the width of the end flange. Two spaced-apart reinforcing ribs  35  (only one shown) are formed in each end flange  18 ′. Each rib extends circumferentially between the sleeve  16 ′ and the lower end of the end flange  18 ′. The ribs  35  are stamped into the sheet steel and form respective channel-shaped recesses  33  in the interior surface. Each end flange  18 ′ defines a bolt hole  37 ′ on the same centerline as the bolt hole in the other end flange. 
   The reaction member has a V-shaped body  34 ′ including a rounded base  36 ′ with outwardly extending legs  38 ′ each of which terminates in a straight upper end. Each of the legs  38 ′ defines a bolt hole  39 ′ which is larger than the bolt holes in the end flanges  18 ′ for accommodating the change in angularity of the legs  38 ′ with the tightening of the clamp. When the outer ends of the legs  38 ′ are in engagement with the retainer ears  22 ′, as shown, the centerlines of the bolt holes  39 ′ are spaced from the retainer ears  22 ′ by the same distance as the bolt holes  37 ′. The reaction member  26 ′ also comprises a pair of arcuate support plates  41 ′ (only one shown) each of which is unitary with the V-shaped body  34 ′. The support plates  41 ′ are located at opposite ends of the V-shaped body and are suitably stamped out of the body between the bolt holes  39 ′ and the ends of the body. Each support plate  41 ′ is located in alignment with one pair of reinforcing ribs  35  and has its ends nested in the channel-shaped recess  33 . The arcuate support plates  41 ′ have a curvature substantially the same as the sleeve  16 ′ and are adapted to seat against the outer surface of the adjacent pipe when the clamp is tightened. The support plates  41 ′ serve to increase the strength of the pipe joint and to improve the sealing capability of the joint. 
   The band clamp  10 ′ is used in the same manner as band clamp  10  of the first embodiment described above. 
   The Third Embodiment of the Invention 
   The third embodiment of the invention will be described with reference to  FIGS. 5 and 6 . The band clamp  10 ″ of this embodiment has a clamp tightening mechanism  14 ″ which, except for the bolt and nut, is unitary with the sleeve  16 ″. In the description of the third embodiment, those parts which are similar to but not identical to corresponding parts of the second embodiment are designated by the same reference numbers but with the addition of a double prime symbol, e.g.  10 ″. 
   Referring now to  FIGS. 5 and 6 , the clamp tightening mechanism  14 ″ comprises a pair of end flanges  18   a  and  18   b , a reaction member  26 ″, and like the first embodiment, a bolt  28  and nut  32 . The difference between this embodiment and the second embodiment is that the V-shaped reaction member  26 ″, which comprises a rounded base  36 ″ and legs  38   a  and  38   b , is unitary with the clamp sleeve  16 ″. The flange  18   b  terminates in a retainer ear  22 ″. It is noted that the leg  38   a  of the V-shaped reaction member  26 ″ is joined with the end flange  18   a  by a bight  43  which is unitary with the leg  38   a  and the end flange  18   a . Thus, the entire band clamp  10 ″, except for the bolt and nut, is made of one piece of sheet metal. 
   The band clamp  10 ″ is used in the same manner as the band clamp  10  of the first embodiment described above. 
   It will thus be apparent that there has been provided in accordance with the present invention a band clamp which achieves the aims and advantages specified herein. It will of course be understood that the foregoing description is of preferred exemplary embodiments of the invention and that the invention is not limited to the specific embodiments shown. Various changes and modifications will become apparent to those skilled in the art. For example, the reaction member of the embodiment of  FIGS. 1–3  could be implemented as a unitary extension of one of the end flanges, rather than as a separate component. All such variations and modifications are intended to come within the scope of the appended claims. 
   As used in this specification and appended claims, the terms “for example” and “such as,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.