Abstract:
The invention concerns a connection between a largely rigid pipeline and a flexible conduit element by means of a steel nipple, reaching with its one end into the pipeline and with its opposite end into the flexible conduit element, wherein the flexible conduit element is secured to the nipple by means of a clamping sleeve. The basic problem, to configure a flow-favorable connection between a rigid pipeline and a flexible conduit element so that a compact tie-in of the flexible conduit element is possible without the materials being affected by the type of connection technique, is solved in that the pipeline in the segment receiving the nipple and the clamping sleeve are subjected to magnetic pulse shaping coils to reduce a cross section thereof and the pipeline and the nipple have substantially the same inner diameter.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. 10 2007 021 846.1-12, filed May 5, 2007, the entire disclosure of which is hereby incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The invention concerns a connection between a rigid pipeline and a flexible conduit element. The invention, furthermore, concerns a method for making such a connection between a rigid pipeline and a flexible conduit element. 
       BACKGROUND OF THE INVENTION 
       [0003]    Connections of the mentioned kind find application, for example, in refrigerant fluid lines, where for space and/or weight reasons or for reasons of a special requirement on the specific properties for the lines, the use of different materials may be necessary. Metallic materials, if possible, are joined by traditional welding or soldering. This, however, entails residues of the welding or soldering agents and/or high energy input and, what is more, it cannot be used for certain materials or combinations of materials. Flexible hoses can be fastened to stable-shape nipples by mechanically crimped or squeezed clamping sleeves, in which case there are very high demands on the precision of the process in order to achieve a stable and especially a tight connection. 
         [0004]    From EP 0 154 588 B1 is known a pipe to pipe connection, whereby in a detachable coupling of two pipes joined via a sleeve and a tightening screw, a gasket is joined firmly to one pipe by electromagnetic shaping for purpose of a sealing by surface contact, before the connection between the two pipes is made by tightening the nut. 
         [0005]    FP 0 841 108 A1 shows the connection of a metal pipe, having a plastic jacket, to a metallic fitting by magnetic pulse shaping, wherein the fitting reaches into the pipe and has projections on its outside for a secure joining to the inside of the pipe as it is deformed. 
         [0006]    Thus, the two publications show the possibility of using magnetic pulse shaping in the joining of pipelines, but give no hint as to the possibility of improving pipe to hose connections by the use of magnetic pulse shaping. 
         [0007]    U.S. Pat. No. 5,961,157 shows a connection between a rigid pipeline and a flexible conduit element by means of a nipple, where the pipeline is expanded in its terminal segment. The nipple has a thickening at the end face, which comes to bear against a shoulder of the pipeline at the beginning of the expansion, while the expanded region is reduced in its cross section by a mechanically produced corrugated folding. The diameter resulting from the folding is smaller than the diameter of the thickening of the nipple. In the region of the folding, the flexible conduit element is squeezed between the pipeline and the nipple. The drawback in this configuration is the reduction of the flow diameter at the transition between the individual elements and the absence of a tight connection between the nipple and the pipeline. 
         [0008]    Starting from the known prior art, the basic problem of the invention is to organize the configuration and production of a connection between a rigid pipeline and a flexible conduit element so that a compact tie-in of the flexible conduit element is possible without the materials being affected by the type of connection technique. 
       SUMMARY OF THE INVENTION 
       [0009]    In concordance with the instant disclosure, this problem is surprisingly solved for this type of connection by a configuration with the features described herein. 
         [0010]    Here, the connection between the rigid pipeline and the flexible conduit element is produced by a nipple, which is partly accommodated in the pipeline and partly in the flexible conduit element, joining the two conduit elements. Both the segment of the pipeline accommodating the nipple and the clamping sleeve for fixing the nipple to the flexible conduit element can be squeezed to reduce their cross section by magnetic pulse shaping. Under the effect of magnetic pulse shaping, the sleevelike elements are pressed together so that the elements are reduced in their free inner diameter for the most part uniformly and concentrically across their circumference and thus a radially inwardly acting force is exerted, by which the inside of the pipeline and the inside of the clamping sleeve are pressed and fixed against the outer circumference of the nipple, while the flexible conduit element is clamped and fixed between the inside of the clamping sleeve and the nipple. 
         [0011]    The contraction of the clamping sleeve and the corresponding segments of the pipeline occurs in the entire region subjected to the magnetic pulse shaping. The choice of the parameters, such as the field strength of the electromagnetic field, the wall thickness of the elements being deformed, and the inner diameter of the elements prior to the deformation is done so that the elements being deformed are molded onto the nipple as a certain compressive force is built up, and the elements as they are deformed are able to mold themselves against a predetermined contour of the nipple. Since the nipple forms the abutment for the molding on of the pipeline and/or the clamping sleeve, it must have at least the same hardness as the components being deformed. 
         [0012]    Also, the strength of the clamping sleeve is greater than that of the pipeline segment being deformed. 
         [0013]    With the use of magnetic pulse shaping and the choice of materials, dimensions, and structural shapes made possible by this, not only is a compact, tight hose arrangement possible via the nipple arranged on the pipeline, but also the possible minimization of the diameter can minimize the surfaces of the flexible conduit element which are wetted by the fluid and, thus, the permeation of fluid through it. In particular, thanks to the invention, one can join a nipple of steel, for example, having a correspondingly slight thickness, to a pipe made of another metal, such as aluminum. 
         [0014]    As the pipeline has an inner diameter largely conforming to the inner diameter of the nipple and a terminal broadening to accommodate the nipple, there is no change in the free flow cross section of the piping system. This leads, on the one hand, to improved noise behavior in the piping system and, on the other hand, to the lowest possible pressure loss in this area. 
         [0015]    Advantageously, the clamping sleeve is joined as a separate part to the rigid pipeline or to the nipple and firmly connected to it, while the joining can be done by any known method, including magnetic pulse shaping. 
         [0016]    In an alternative configuration, the clamping sleeve is part of the pipeline, while the pipeline in this second segment, further broadened with respect to the first segment, has an inner diameter which is suited to accommodating the flexible conduit element, into which the nipple is partly shoved. The broadening of the pipeline is chosen such that the flexible conduit element can be shoved into the expanded segment without expenditure of force or deformation. 
         [0017]    Furthermore, it is in the meaning of the invention to connect the nipple permanently to the pipeline as protection against axial shifting and against twisting, so that after the connection the nipple can no longer be moved in the segment of the pipeline receiving it. Preferably, the connection is bonded, but it can also be a form fit or a friction fit. 
         [0018]    It is especially advisable to weld the pipeline and the nipple by means of a magnetic pulse, after or at the same time as the magnetic pulse shaping, so as to produce a durable, tight and not releasable connection between the outside of the nipple and the inside of the pipeline. 
         [0019]    With this type of microcontact surface welding, the corrosion vulnerability of the components caused by the welding process is increased to a lesser extent than for traditional welding methods. 
         [0020]    Advantageously, the nipple has projections and/or depressions on its outer surface, which protect the arrangement of the nipple on both the pipeline segment receiving the nipple a d on the clamping sleeve or on the corresponding pipeline segment against axial displacement. An axial securement is created by the molding of the pipeline and the clamping sleeve onto the rigid nipple and thus also onto the projections and/or depressions of the nipple by the magnetic pulse shaping. 
         [0021]    In a favorable embodiment of the invention, a protection against axial displacement is also arranged between the flexible conduit element and the nipple and/or between the flexible conduit element and the clamping sleeve, so as to prevent a separating of these elements after the magnetic pulse shaping, for example, during the operation of a refrigerant piping system. The protection can also be integrated into the clamping sleeve. 
         [0022]    Furthermore, it can also be advisable to provide a seal, especially an annular one, between nipple and flexible conduit element, in order to prevent the escape of fluids from the piping system at this joint surface, and also advantageously the seal is inserted at least partly into a radial, circumferential recess on the nipple, and when the flexible conduit element is pressed against the nipple the seal is squeezed between these two components and a seal is formed between the two components in the axial direction. 
         [0023]    As a further advantageous supplement to the invention, it is proposed to configure the pipeline in the segment receiving the nipple and/or the clamping hose in its segment receiving the flexible conduit element with an additional outer sleeve made from an electrically conductive, strong material. 
         [0024]    With this additional sleeve, on which the magnetic pulse shaping acts, it is possible to improve, sustain, or even replace its cross section reducing action on the pipeline and the clamping sleeve, in order to achieve the desired degree of shaping for the pipeline. 
         [0025]    The underlying problem of the invention, moreover, is solved by a method. The end of the pipeline is first broadened in order to receive the nipple, which has an inner diameter largely identical to the nonbroadened pipeline, and then fix it on the pipeline by the cross section reducing action of the magnetic pulse shaping. The molding-on by magnetic pulse shaping can occur in one or more steps. 
         [0026]    Moreover, advantageously, the flexible conduit element partly shoved onto the nipple is fixed on the nipple by means of a clamping sleeve, joined to the rigid conduit element or the nipple, wherein the clamping sleeve embraces the flexible conduit element on the outside and is uniformly squeezed by magnetic pulse shaping to reduce its cross section and secure the flexible conduit element arranged between the nipple and the clamping sleeve. 
         [0027]    In order to accelerate the method of producing the connection, furthermore advantageously several magnetic coils can be used at the same time, surrounding the treated pipeline segments concentrically and at a radial spacing, in order to subject the pipeline and the sleeve together to a magnetic pulse shaping. 
         [0028]    In one embodiment, a connection between a largely rigid pipeline and a flexible conduit element is formed by means of a largely rigid nipple. The nipple reaches with its one end into the pipeline and with its opposite end into the flexible conduit element. The flexible conduit element is secured to the nipple by means of a clamping sleeve. The connection further includes the pipeline having an inner diameter largely corresponding to the inner diameter of the nipple. The pipeline has a broadening at the end to receive the nipple. The pipeline in the region of the segment receiving the nipple and the clamping sleeve are both squeezed by magnetic pulse shaping to reduce their cross sections. 
         [0029]    In another embodiment, a method for connecting a largely rigid conduit element and a flexible conduit element by means of a nipple includes the steps of: broadening a free end of the pipeline to receive the nipple, the nipple connected to the flexible conduit element; introducing the nipple into the broadening; and concentrically molding the broadened segment of the pipeline on the nipple in a crimped connection by a magnetic pulse shaping. A connection between the largely rigid pipeline and the flexible conduit element by means of the largely rigid nipple is thereby provided. 
     
    
     
       DRAWINGS 
         [0030]    The above, as well as other advantages of the present disclosure, will become readily apparent to those skilled in the art from the following detailed description, particularly when considered in the light of the drawings described herein. The drawing shows: 
           [0031]      FIGS. 1   a - c  shows the individual steps of a connection of a rigid pipeline to a flexible conduit element in longitudinal section, 
           [0032]      FIGS. 2   a - b  show the connection shown in  FIGS. 1   a - c  with parts preassembled, 
           [0033]      FIGS. 3   a - d  show the connection shown in  FIGS. 2   a - b  in an alternative embodiment, 
           [0034]      FIGS. 4   a - b  show the connection shown in  FIGS. 1   a - c  with an additional outer sleeve to strengthen the effect of the magnetic pulse shaping, and 
           [0035]      FIG. 5  shows the arrangement of the clamping sleeve on the nipple with additional axial securement. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should also be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, are not necessary or critical. 
         [0037]    In the figures of the drawing, the same structural parts are given the same reference numbers. 
         [0038]      FIGS. 1   a - c  show the coupling in piping system, specifically, the connection of a rigid pipeline  10 , configured as an aluminum pipe, for example, to a flexible conduit element, configured as a hose  12 , wherein the flexible hose is a polymer hose, for example. 
         [0039]    The connection shown in  FIG. 1   a - c  between the aluminum pipeline  10  and the polymer hose  12  occurs via a nipple  14  made of stainless steel, which is connected to the two components of the piping system. The nipple  14  is in the form of a cylindrical sleeve, which reaches by one end segment into the pipeline  10  and by the opposite end segment into the hose  12 . 
         [0040]    In this embodiment of the invention, no other components are needed for the connection between the rigid pipeline  10  of aluminum and the flexible hose  12  of polymer. 
         [0041]    Both the nipple  14  and the hose  12  are received by the pipeline  10 , which for this purpose has segments  10   b ,  10   c  which are broadened relative to the segment  10   a , which corresponds in its inner and outer diameter to the dimensions of the pipeline itself. In segments  10   b ,  10   c , the pipeline is broadened in one stage at a time, while the wall thickness is largely the same as in segment  10   a . Segment  10   b  with the first broadening stage is suitable to receive and secure the nipple  14 , while the second broadening stage, located in the terminal segment  10   c  of the pipeline, is designed to receive the nipple and the hose  12 , embracing it. 
         [0042]    As is especially noticeable from  FIG. 1   a , the inner diameter of the pipeline  10  in segment  10   b  is slightly larger than the outer diameter of the nipple  14 , so that this can be shoved in simple fashion and without fear of getting stuck into the region of the pipeline where the segment  10   b  passes by a steplike reduction of cross section into segment  10   a  and thus into the form of the nonbroadened pipeline  10 . This steplike transition forms a stop when introducing the nipple  14 , against which the nipple can rest. 
         [0043]    The circular inner diameter of the nipple, configured as a cylindrical sleeve, corresponds ideally to the inner diameter of the pipeline  10  in its nonbroadened segment  10   a , so that the fluid circulating in the system can flow through the clear passage of the nipple into the pipeline  10  without changes in cross section or steps causing turbulence with corresponding pressure loss and/or emission of noise in the pipeline. 
         [0044]    As shown in  FIG. 1   a - c , in the method of the invention one arranges electromagnetic coils  16  in the region of the segments  10   b ,  10   c  of the pipeline being deformed, so as to induce eddy currents by the resulting magnetic field in the pipeline segments consisting of an electrically conductive material, while the current flowing in the magnetic field generates a force directed into the interior of the pipeline segments. The coils are each arranged concentrically to the pipeline segments being worked upon. 
         [0045]    This force results in the cross section reducing deformation of the segments  10   b ,  10   c  under the action of the magnetic pulse shaping, as shown in  FIGS. 1   b  and  1   c , while the shaping of the two segments occurs in succession and the hose  12  is only shoved onto the nipple, now firmly arranged on the pipeline  10 , after the shaping of the pipeline segment  10   b , as shown in  FIG. 1   b . The steplike transition between the segments  10   c  and  10   b  forms a stop for the hose when it is introduced into the segment  10   c  of the pipeline. 
         [0046]    During the deformation shown in  FIG. 1   b , not only a magnetic pulse shaping but also a magnetic pulse welding takes place, by which the stainless steel nipple  14  is firmly and inseparably connected to the aluminum pipeline  10  with improvement of its torsional strength. By an at least partial welding of the pipeline segment  10   b  to the nipple  14 , the hold between the two components is provided not only by a frictional fit, but also by a bonding fit or a form fit. 
         [0047]    In particular, the bonding connection of the nipple  14  to the pipeline  10  also improves the tightness to leakage of fluid in this area. 
         [0048]    In the regions of the transitions between the individual segments of the pipeline, the deformations due to the magnetic pulse shaping are not as great, since these transitions for the most part extend in the radial direction and thus have a relatively large wall thickness in the direction of the force bringing about the deformation. Also, these transitions lie in the marginal regions of the respective magnetic field. 
         [0049]    The nipple  14  in the embodiment depicted has two radial grooves  14   a  with an axial spacing, in each of which an O-ring  18  is inserted, the O-rings forming a seal between the hose  12  and the nipple  14 , thus preventing an escape of fluid along the axially extending bearing surface. 
         [0050]    Under the action of the deformed segment  10   c  of the pipeline, the corresponding segment of the hose is clamped between the segment  10   c  of the pipeline and the nipple  14 , and in this way it is fixed in the manner of a hose clip. The flexible hose is also compressed in its wall thickness, but without affecting the free flow cross section for the fluid in this region, since this is formed by the inner diameter of the largely shape-stable steel nipple in this region. 
         [0051]      FIGS. 2   a ,  2   b  show how the aforementioned coupling takes place in only a single work step with a nipple  14  preassembled with the hose  12  and two magnetic pulse coils  16 ,  16   a . The nipple  14 , preassembled with the hose  12 , is inserted into the terminal segment of the pipeline  10 , which has been broadened into two steps, and the segments  10   b ,  10   c  are deformed to reduce their cross section by the eddy current fields generated by means of the magnetic pulse coils  16 ,  16   a.    
         [0052]    In the alternative embodiment of the invention shown in  FIG. 3   a - d , the pipeline  10  is only broadened in one step at the end to receive the nipple  14  in the segment  10   b , forming the end segment of the pipeline. In a first step, magnetic pulse coils  16  at first mold the aluminum of the pipeline  10  by magnetic pulse shaping onto the nipple  14  and then, depending on the choice of coils, it can be connected at the same time or in a further step to the refined steel of the nipple by magnetic pulse shaping. 
         [0053]    After the fastening of the nipple  14  to the pipeline  10 , a preassembled unit consisting of the hose  12  and a separate clamping sleeve  20 , encircling the hose, is shoved onto the end of the nipple  14  opposite the pipeline and fastened onto the nipple  14  by pressing, thanks to a magnetic pulse shaping with the coils  16 . The separate clamping sleeve  20  is rotationally symmetrical and cup shaped, while the bottom  20   a  of the cup shape has an opening concentric to the lengthwise axis of the clamping sleeve, with which the clamping sleeve can be shoved onto the nipple  14 . The diameter of this opening is only slightly larger than the outer diameter of the nipple  14 , so that the bottom  20   a  can be brought to bear directly against the nipple, despite its radial orientation, by the magnetic pulse shaping, so as to increase the hold of the clamping sleeve on the nipple. In addition, there is an active connection and a form fit thanks to the crimping of the hose  12  between the deformed clamping sleeve  20  and the outer surface of the shape-stable nipple  14  and the resulting frictional fit of the hose at its inner surface with the nipple and at its outer surface with the clamping sleeve. In the manner described above, sealing rings  18  can be arranged between the nipple and the hose. 
         [0054]    By the segment  20   a , the clamping sleeve can also be joined in a first step to the nipple  14  or the pipeline segment  10   b  by conventional methods, and then prior to the cross section reducing magnetic pulse shaping of the clamping sleeve  20  the hose  12  is shoved between the nipple  14  and the clamping sleeve. 
         [0055]    A further alternative embodiment of the invention is shown in  FIG. 4   a ,  4   b . in this variant, the pipeline  10  is broadened at the end in two stages to receive the nipple and the hose. But the eddy current field producing the deformation of the segments  10   b ,  10   c  is not induced in the pipeline itself, but rather in separate clamping sleeves  24 ,  26 , which surround the pipeline segments  10   b ,  10   c  being deformed. The desired deformation of the pipeline segments  10   b ,  10   c  occurs indirectly, in that the clamping sleeves are deformed and these then act like presses to deform the pipeline segments. This alternative arrangement is especially advantageous when a particularly high degree of forming of the pipeline segments is necessary and/or the pipeline consists of an only slightly electrically conductive material. The material of the clamping sleeves, which does not make contact with the fluid from the piping system, can be chosen solely by the criteria of deformability and suitability for transmission of forces onto a body concentrically surrounding the material. The sole function of the clamping sleeves is to realize the desired deformation of the pipeline segments  10   b ,  10   c , so as to arrange the nipple  14  both on the pipeline  10  and on the hose  12 . 
         [0056]    In the event that the nipple  14  is supposed to be formed from aluminum or a similar malleable material and therefore it would no longer be strong enough to serve as the abutment for the deformation of the pipeline and the clamping sleeve, without itself becoming deformed in cross section, the nipple can be configured with an inner sleeve (not shown) of steel or another deformation-resistant material on its inner surface, at least in the regions exposed to stress by the molding of the pipeline and/or the clamping sleeve under the action of the magnetic pulse. Such an inner reinforcement sleeve for the nipple can be used in all of the sample embodiments. 
         [0057]      FIG. 5  shows a hose  12 , which similar to the previously described sample embodiments is squeezed by the molding of a clamping sleeve  20  onto a steel nipple  14  between these two elements through magnetic pulse shaping and is secured in this way. The nipple  14  in this sample embodiment has securements against an axial displacement of the individual elements relative to each other. First, the bottom  20   a  of the clamping sleeve  20  is secured by axially spaced projections on the nipple  14 , forming a radial circumferential groove  15 , and furthermore can be connected firmly to the nipple  14  by traditional joining methods. Secondly, the nipple  14  has a projection  17 , across which the hose  12  is shoved, and which forms a hook acting against the direction of pull-off of the hose  12  when the hose  12  is squeezed between the clamping sleeve and the nipple  14  by the pulse shaping. 
         [0058]    As further axial securement, a ring  28  is provided, arranged concentric to the lengthwise axis of the nipple  14  and the hose  12 , consisting of a harder material than the clamping sleeve  20 , preferably steel, and being arranged between the latter and the hose  12 . When the clamping sleeve is molded during the pulse shaping, the hose  12  is squeezed together in the region of the ring  28  and the clamping sleeve  20  is molded onto the harder ring  28 . Thus, an axial securement is formed between the clamping sleeve and the hose  12  and, by interacting with the hook  17 , also an axial securement of this unit relative to the nipple  14 , wherein the ring  28  can be arranged in front of or behind the hook  17  in the pull-off direction. 
         [0059]    The radially circumferential sealing rings  18  squeezed together after the pulse shaping also form an axial securement between the hose  12  and the nipple  14 . 
         [0060]    Furthermore, the hose  12  has a diameter reduction at its end, in the form of a shoulder  13 , and the clamping sleeve  20  comes to bear against the diameter reduced region thanks to the pulse shaping, and the end face of the clamping sleeve forms a stop for the shoulder  13  of the hose in the entering direction. 
         [0061]    Thus, with the present invention, it is possible to connect a coupling between a rigid pipeline and a flexible hose in simple and reliable manner by means of a nipple, connecting the two components, without the connection impairing or weakening the material or the structure of the components. The invented design is for the most part free of changes in the flow cross section or leakage. 
         [0062]    While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes may be made without departing from the scope of the disclosure, which is further described in the following appended claims.