Abstract:
A method for manufacturing a connection between a hose and coaxial line section is provided. The method includes providing an outer pipe, inserting an inner pipe along with a hose situated at least partially on an outer periphery of the inner pipe inside the outer pipe, and deforming the outer pipe, the inner pipe or both so that the hose becomes clamped between the inner pipe and outer pipe. A coaxial line section for a refrigerant circuit of a motor vehicle also is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Patent Application No. 10 2012 002 994.2, filed Feb. 15, 2012, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The technical field relates to a coaxial line section for an air conditioning system of a motor vehicle, as well as to a method for manufacturing a coaxial line section. 
     BACKGROUND 
     A connection device is known from DE 10 2007 042 841 A1. The connection device disclosed therein encompasses at least one coaxial pipe with an inner and outer area or arrangement with at least one inner pipe and one outer pipe, wherein there is a communicating connection between one end of the coaxial pipe or pipe arrangement and a connecting piece, wherein the connecting piece exhibits at least one first and one second terminal each having an opening, wherein the opening of the first and/or second terminal establishes a communicating connection between a hose and the connecting piece. The hose can here be positively crimped with the connecting piece. 
     Accordingly, it is desirable to provide a coaxial line section for a refrigerant circuit of a motor vehicle and a method for manufacturing the coaxial line section, which makes it possible to do without a connecting piece between an outer pipe and inner pipe on a hose connection. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
     SUMMARY 
     In accordance with an exemplary embodiment, a method for manufacturing a connection between a hose and a coaxial line section exhibits the following steps:
         a) Provision of an outer pipe,   b) Insertion of an inner pipe along with a hose situated at least partially on the outer periphery of the inner pipe inside the outer pipe, and   c) Deformation of at least one of the pipes, so that the hose becomes clamped between the inner pipe and outer pipe.       

     This method yields a connection between a coaxial line section and a hose, by which the hose can be directly joined to the outer pipe and inner pipe without an additional element. At the same time, the outer pipe can be sealed fluid-tight at the end by the constriction around the hose. The hose can here be arranged on a section of the outer pipe that is provided with an expansion. The constriction of the outer pipe around the hose at the end section can be created in a crimping process. As a consequence, the hose itself serves as a seal between the outer pipe and inner pipe. At the same time, the pipe is connected with the hose so as to be able to carry a fluid. 
     One embodiment provides the outer pipe with an expansion having an inner diameter, wherein the inner diameter is large enough to accommodate the hose. 
     The expansion can be generated in an additional procedural step, or already be provided on the pipe. For example, the expansion can be created by a mandrel penetrating into the outer pipe. The inner pipe with hose situated thereupon is inserted into the expansion in such a way that the hose projects a ways into the expansion, and can thus be encircled during outer pipe constriction or during expansion. The outer pipe is then deformed in the expansion area, thereby clamping the hose. 
     In another embodiment, a connection point for a junction is provided in the expansion between the hose and an unexpanded area of the outer pipe. 
     The connection point for the junction can here be formed by a borehole that penetrates through the expansion, as well as a soldered-on or welded-on line section. In the junction, a liquid flowing between the outer pipe and inner pipe, for example the refrigerant of an air conditioning system, can be introduced into the outer tube or discharged from the outer tube. An enlarged space created by the expansion serves as a collection point for the refrigerant during operation. 
     In an advantageous further embodiment, a fluting is provided on the outer periphery of the inner pipe. 
     As the outer pipe constricts, the hose material is compressed and elastically pressed into the fluting on the inner pipe. The fluting improves the tightness of the connection between the inner pipe and the hose. 
     In addition, in a further embodiment of the method, the outer pipe is provided with a fluting. The fluting for example is provided in the area of contact with the hose, and improves the tightness of the hose connection in the manner described above. 
     In an embodiment, the method further includes providing the interior side of the outer pipe with ribs. The ribs can here extend in the outer pipe up to a section in which the expansion is provided. The ribs can be provided by machining the interior side of a correspondingly thick-walled outer pipe in such a way as to produce ribs, for example by milling, stamping or rolling out free spaces. The ribs can also be fabricated in an extrusion process, in which a metal semi-finished part is pressed under a high pressure through a mask exhibiting the later cross section of the outer pipe, wherein the ribs extend inwardly from a ring section on the outer periphery. The expansion preferably does not incorporate any ribs, which can be milled out on the end given an outer pipe fabricated in an extrusion process. 
     Of course, the outer periphery of the inner pipe can also be provided with ribs, so as to improve heat transfer. 
     In another advantageous embodiment of the method, a sealing element is arranged between the inner pipe and hose. The sealing element can consist of a flexible material, and improve the seal between the inner pipe and hose. Two sealing elements are preferably situated axially parallel relative to each other in an area encircled by the constricted section of the outer pipe. 
     The method yields a coaxial line section, with an outer pipe and an inner pipe, as well as a hose clamped fluid-tight between the outer pipe and inner pipe in an end area. The coaxial line section is used in the refrigeration circuit of a motor vehicle. The inner pipe is joined in a fluid-carrying manner with a carburetor. The outer pipe is joined on one side with an expansion valve in a fluid-carrying manner, and joined by way of a junction with a capacitor in a fluid-carrying manner. The hose is joined with a compressor in a fluid-carrying manner. 
     Such an arrangement makes it possible to improve the efficiency of a refrigeration circuit, since the refrigerant in a gaseous, heated aggregate state can release heat to the liquid phase that prevails in front of the carburetor. In addition, a collection tank can be situated between the junction and capacitor for collecting and drying the refrigerant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  schematically depicts a refrigeration circuit, which exhibits a hose arranged in a coaxial line section; 
         FIG. 2   a ) is a cross-sectional view an outer pipe before a deformation process in accordance with an exemplary embodiment; 
         FIG. 2   b ) is a cross-sectional view of an outer pipe that regionally exhibits an expansion, in accordance with an exemplary embodiment; 
         FIG. 2   c ) is a cross-sectional view of an outer pipe that incorporates an inner pipe, as well as a hose arranged at the end on the inner pipe and slipped onto the inner pipe, in accordance with an exemplary embodiment; 
         FIG. 2 d   ) is a cross-sectional view of a connection between a hose and a coaxial line section, in which a constriction positively and non-positively envelops the hose, in accordance with an exemplary embodiment; 
         FIG. 3  is a cross-sectional view of the arrangement of  FIG. 2  with a junction that empties into a collection point at a connection point, in accordance with an exemplary embodiment; 
         FIG. 4  is a cross-sectional view of a coaxial line section in which sealing elements are arranged between the inner pipe and hose; 
         FIG. 5  schematically depicts a procedural sequence for manufacturing a hose arrangement on a coaxial line section; and 
         FIG. 6  is a cross-sectional view of an embodiment for an outer pipe with fluting. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the various embodiments or the application and uses thereof. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
     Identical or similar components on the figures are provided with the same reference number. 
       FIG. 1  schematically depicts a refrigerant circuit  1  for arrangement in a motor vehicle (not shown). A refrigerant circulates in the refrigerant circuit  1 , so that a heat flow QW can be absorbed from an internal space, and a heat flow QK can be released to the environment. The refrigerant is compressed in a gaseous state in a compressor  2 . The compressor  2  can be driven in a manner not depicted, for example by means of an endless belt coupled with an internal combustion engine. While the refrigerant is being compressed in the compressor  2 , the pressure of the refrigerant increases, and the refrigerant becomes warm in the process. The heat can be released to the environment via the heat flow QK in a capacitor  3 . In the capacitor  3 , the refrigerant is liquefied during release of the heat flow QK. An output  4  of the capacitor  3  is joined in a fluid-carrying manner with an input of a collection tank  5 . The refrigerant can accumulate in the collection tank  5  until it gets into a coaxial line section  7  by way of a connection  6 . The coaxial line section  7  exhibits an outer pipe  8  and an inner pipe  9  arranged therein. The liquid refrigerant flows through the junction  6  and thereby gets into the outer pipe  8 , before it is expanded at an expansion valve  23 . During expansion at the expansion valve  23 , the refrigerant cools, so that it can absorb a heat flow QW from the vehicle interior. The heat flow QW is here absorbed at a carburetor  10 . After passing the carburetor  10 , the refrigerant is present in an essentially gaseous phase. It enters into a hose  11  through the inner pipe  9 . The hose  11  is joined with a suction side  12  of the compressor  2 . In the outer pipe  8 , the refrigerant releases heat to the cooled and gaseous refrigerant flowing through the inner pipe  9 . The efficiency of the refrigerant circuit  1  can be improved by bringing together the otherwise separate line sections before the expansion valve  23  and after the carburetor  10 . 
       FIG. 2   a ) shows the outer pipe  8  before a first procedural step, which provides for expanding the outer pipe  8 . The outer pipe  8  can be expanded by means of a mandrel or in an internal high pressure forming process. The outer pipe  8  incorporates ribs  13 , which improve the release of heat to the outer pipe  8 , and extend roughly up until a section  14  in which the outer pipe  8  is later expanded. The outer pipe  8  can be manufactured in an extrusion process. The ribs  13  can here be fabricated at the same time. In the section  14  incorporating the expansion, the ribs  13  can be ground out in a milling process. 
       FIG. 2   b ) shows the outer pipe  8  with an expansion  15 . In the expansion  15 , an inner diameter “da” of the outer pipe  8  is enlarged in relation to an inner diameter “di” of the outer pipe in the unexpanded section  16 . 
       FIG. 2   c ) shows an exemplary embodiment of a third procedural step, in which the inner pipe  9  is inserted into the outer pipe  8 . A hose  11  is slipped onto an end section  25  of the inner pipe  9 . 
     The hose  11  here extends a bit into the expansion  15 . The outer periphery of the inner pipe  9  is provided with a fluting  17 , which ensures a fluid-tight fit of the hose  11  on the inner pipe  9 . The fluting  17  can here consist of continuous grooves and elevations. The hose  11  is made out of an elastic material, for example crude or vulcanized rubber. If necessary, the hose  11  can be fiber-reinforced. 
       FIG. 2   d ) shows a state that arises after the expansion  15  has been constricted in the area of a constriction  20  around the hose  11 , in accordance with an embodiment. As a result, the hose  11  is clamped between the outer pipe  8  and inner pipe  9 . The constriction  20  can be established in a crimping process. In the area outside of elevations  18 , valleys  19  are formed via a correspondingly magnified contact pressure, which acts radially inward. The interaction between the valleys  19  and elevations  18  causes the hose  11  to be positively held against the outer pipe  8 . This seals the area inside the outer pipe  8  fluid-tight in relation to the environment. At the same time, the hose  11  is pressed against the inner pipe  9  strongly enough to also ensure a fluid-tight connection between the inner pipe  9  and hose  11 . In an area between the unexpanded area  16  and constriction  20 , the outer pipe  9  continues to exhibit an enlarged inner diameter “da”, which serves as a collection point  21  for refrigerant. 
       FIG. 3  shows the described arrangement with a junction  6  that empties into the collection point  21  at a connection point  26 , and can be attached to the expansion  15  after the step described in conjunction with  FIG. 2   d ). The junction  6  leads from the collection tank  5  into the coaxial line section  7  (see  FIG. 1 ). Liquid refrigerant here flows in the described manner, and releases its heat to the inner pipe  9 , which is cooled by the cold, gaseous refrigerant. The oppositely changing temperature gradients as the flow passes through the coaxial line section  7  here yields good heat transfer characteristics. 
       FIG. 4  shows a coaxial line section  7 , in accordance with another embodiment, in which the inner pipe  9  and hose  11  have arranged between them sealing elements  22  that improve the fluid-tight seal of the hose  11  in relation to the environment and collection area  21 . The sealing elements  22  can be situated between the inner pipe  9  and hose  11  before establishing the constriction  20 . In this case, the steps described in conjunction with  FIGS. 2   c ) and  2   d ) must be enhanced by the step of introducing the sealing elements  22 . 
       FIG. 5  schematically depicts a procedural sequence for manufacturing a connection between a hose  11  and coaxial line section  7 , which consists of an inner pipe  9  and outer pipe  8 . Step a encompasses the preparation of an outer pipe, step b encompasses the creation of an expansion on the outer pipe, step c encompasses the insertion of an inner pipe  9  as well as a hose  11  slipped onto the inner pipe  9  into the expansion  15 , and step d encompasses the creation of a constriction  20  on the outer pipe  8  in the area of an end section  25 , so that the hose  11  becomes clamped between the inner pipe  9  and outer pipe  8 . 
       FIG. 6  shows a connection in its state in step c), in which a fluting  24  is provided inside on the outer pipe  8  to go along with the fluting  17  on the inner pipe  9 . 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.