Patent Publication Number: US-8966923-B2

Title: Coupling unit for connecting the refrigerant lines of a refrigerant circuit

Description:
RELATED APPLICATIONS 
     This application is the National Stage of International Patent Application No. PCT/EP2011/050110, filed on Jan. 5, 2011,which claims priority to all the advantages of German Patent Applications No. DE 10 2010 004294.3, filed on Jan. 11 2010. 
     The invention relates to a coupling unit for connecting the refrigerant lines of a refrigerant circuit, in particular for cooling a vehicle drive module. 
     In refrigerant circuits, various components are connected by refrigerant lines. Depending on the spatial layout of the refrigerant circuit on an object to be refrigerated, it may be difficult to connect and disconnect the refrigerant lines, for example for replacing a component of the refrigerant circuit. 
     Further, refrigerant circuits are known in which the refrigerant is divided into several sub-lines at a throttle point. In order to obtain the same refrigerating capacity of all sub-lines, an even distribution of the gas-liquid mix of the refrigerant has to be ensured. This may be problematic especially when the refrigerant circuit is installed in a vehicle, for example for cooling a battery in an electric or hybrid vehicle, because acceleration forces occur and the spatial position of the vehicle changes, for example as the vehicle drives up or down a gradient. 
     It is the object of the invention to provide a coupling unit for connecting refrigerant lines of a refrigerant circuit, which enables a simple connecting and disconnecting of the refrigerant lines. It is a further object of the coupling unit to enable an even distribution of the refrigerant to various sub-lines independent from the spatial position of the refrigerant circuit or from externally acting forces. 
     This object is achieved by means of a coupling unit according to the invention for connecting refrigerant lines of a refrigerant circuit, in particular for cooling a vehicle drive module, said coupling unit having an expansion valve accommodated in the coupling unit, said expansion valve separating the refrigerant circuit into a first and a second sub-area. The coupling unit is connected directly to a refrigerant feed and a refrigerant return for an evaporator, said coupling unit respectively comprising a coupling connection for the refrigerant feed and for the refrigerant return, which are detachably connected to the expansion valve via a common fastening device. The common fastening device includes at least one fastening element that is accessible for connecting and disconnecting from a side of the expansion valve, which faces away from the coupling connections. Thus, the refrigerant lines may be disconnected from the expansion valve or connected to the expansion valve in a simple manner, when the side of the expansion valve, which faces away from the coupling connections, is not accessible. The assembly of the refrigerant circuit is simplified and replacement of the expansion valve is made easier. 
     For example, the expansion valve is mounted on a wall of the coupling unit, in particular on a housing wall that is penetrated by the coupling connections. 
     Preferably, the common fastening device clamps the wall and the expansion valve together. This allows both the wall and the coupling connections of the refrigerant feed and the refrigerant return to be fastened to the expansion valve by means of the common fastening device. 
     In order to seal the location of the wall where it is penetrated by the coupling connections, a seal may be provided between the wall and the expansion valve. 
     An optimal compression of the seal may be achieved by placing the seal in a groove in the wall, with the depth of the groove determining a maximum compression of the seal. 
     It is possible for the seal to be integrally formed with the wall, preferably by two-component injection moulding. 
     According to one embodiment, the expansion valve, the refrigerant feed and the refrigerant return are connected to each other to form a unit that is movably supported on the wall of the coupling unit, as a result of which tolerances and thermal expansions can be compensated. In particular, the wall surrounds the feed and the return as well as the valve, so that the unit is movably received in a kind of housing. 
     A seal may be provided between the wall and the refrigerant feed as well as the refrigerant return. This enables the location where the wall is penetrated by the refrigerant lines to be sealed independently from the expansion valve. 
     Preferably, the wall includes a cylindrical wall section that extends in the direction of the refrigerant feed and the refrigerant return, said seal bearing against the refrigerant feed, the refrigerant return and the cylindrical wall section being preferably movable relative to the wall section and/or the refrigerant feed, the refrigerant return. In this way, the contact surface of the seal is increased and any tolerances in the positioning of the seal relative to the wall are compensated. 
     The relative movement of the seal allows some play that may be limited for example by means of a wall stop. 
     According to one embodiment, the seal comprises a sealing body which is preferably made from a substantially rigid material, on which inner sealing elements for providing a seal between the sealing body and the refrigerant feed as well as the refrigerant return and an outer sealing element for providing a seal between the sealing body and the wall are provided, with the inner and/or outer sealing elements preferably being integrally moulded to the sealing body, in particular by two-component injection moulding. A sealing body of this type allows the refrigerant feed and the refrigerant return to be sealed in a common recess of the wall, especially if the geometries of the lines and of the recess of the wall do not match. 
     The sealing body is preferably in multiple pieces, in particular in two pieces, with the pieces of the sealing body preferably being detachably connected to each other. This allows a simple assembly and a simple replacement of the sealing body on the two lines, by attaching the pieces of the sealing body to the lines in a radial direction. 
     The sealing body is separated particularly along a plane through the centre of the refrigerant feed and/or the refrigerant return. 
     In order to seal the refrigerant circuit on the coupling unit, a seal may respectively be provided between the coupling connections of the refrigerant return and the refrigerant feed and the expansion valve. 
     Preferably, at least one coupling connection of the refrigerant feed and/or of the refrigerant return has a lateral projection which is positioned and fixed between a pressing part of the common fastening device and the expansion valve. The lateral projection of the coupling connection allows a simple positive fixing of the coupling connection on the expansion valve in an axial direction. An example of such a projection is an annular flange. 
     It is possible for at least one coupling connection of the refrigerant feed and/or the refrigerant return to have a lateral indentation, in which a common pressing part engages and fixes the coupling connections in an axial direction. In this way, a simple positive connection between the pressing part and the coupling connections of the refrigerant feed and/or the refrigerant return is made possible. 
     The pressing part may be a comb-shaped plate that can be laterally pushed onto the coupling connections. 
     Moreover, the invention relates to a coupling unit for connecting refrigerant lines of a refrigerant circuit, in particular for cooling a vehicle drive module having a throttle point accommodated in the coupling unit, preferably an expansion valve, and at least one refrigerant line arranged in the refrigerant circuit downstream of the throttle point. The coupling unit comprises a refrigerant distributor having at least two sub-lines combined in the refrigerant distributor, said refrigerant distributor being a coupling connection of the refrigerant line, which forms part of the coupling line and to which the refrigerant line is connected. Since the refrigerant distributor and the throttle point are jointly integrated in the coupling unit, there will be no or only a minor segregation of the liquid and gaseous phases of the refrigerant on the refrigerant distributor after the throttle point. Thus, an even distribution of the liquid phase of the refrigerant to the various sub-lines of the refrigerant distributor takes place. This variant may optionally also be combined with the aforementioned variant that is directed to assembly (from the side facing away from the coupling connections). 
     According to a preferred embodiment, the hydraulic cross section of the refrigerant line remains constant from the throttle point to the refrigerant distributor. 
     The hydraulic cross section is preferably between 3 and 8 mm. 
     It has been found that the length of the refrigerant line between the throttle point and the refrigerant distributor amounts to for example 2 to 10 times the hydraulic cross section of the refrigerant line. 
     The coupling connection may be manufactured directly by moulding the refrigerant return and/or the refrigerant feed. This allows a simple one-piece implementation of the coupling connection with the corresponding refrigerant line. 
     Alternatively, the coupling connection may be a separately produced component which is preferably produced in one piece by turning or milling. This allows a complex geometry of the coupling connection. 
    
    
     
       Further features and advantages of the invention will become evident from the description given below and from the attached drawings to which reference will be made and wherein: 
         FIG. 1  shows a schematic view of a refrigerant circuit having a coupling unit according to the invention; 
         FIG. 2  shows a lateral sectional view of a coupling unit according to the invention; 
         FIG. 3  shows a sectional view of the coupling unit along the line III-III in  FIG. 2 ; 
         FIG. 4  shows a detailed sectional view of a coupling unit according to the invention; 
         FIG. 5  shows a lateral sectional view of the refrigerant distributor from  FIG. 2 ; 
         FIG. 6  shows a sectional view of the refrigerant distributor along the line VI-VI in  FIG. 5 ; 
         FIG. 7  shows a cooling device for a vehicle propulsion battery, which includes a coupling unit according to the invention; 
         FIG. 8  shows a lateral sectional view of a coupling unit according to a further embodiment of the invention; 
         FIG. 9  shows a sectional view of the coupling unit along the line IX-IX of  FIG. 8 ; and 
         FIG. 10  shows a sectional view of the coupling unit along the line X-X of  FIG. 8 . 
     
    
    
       FIG. 1  shows a schematic view of a refrigerant circuit  10 . The refrigerant circuit  10  includes refrigerant lines  11 , through which fluid flows in the direction indicated by the arrows. 
     The refrigerant circuit  10  comprises a compressor  12  in which the refrigerant is compressed and a condenser  14  in which the refrigerant is cooled and condensed. 
     A coupling unit  16  has a throttle point  18  that is formed as an expansion valve  20 , and a refrigerant distributor  22  that divides the refrigerant line  11  into several sub-lines  24 . An evaporator  26  is provided in each sub-line  24 , which is particularly arranged to cool a vehicle drive module, for example a vehicle propulsion battery of a purely battery driven or a hybrid vehicle. 
     The refrigerant is returned from the evaporators  26  via a common refrigerant line  11 , which in turn leads through the coupling unit  16  to the compressor  12  and closes the refrigerant circuit  10 . 
     The coupling unit  16  is provided in a wall  28  which separates the refrigerant circuit  10  into a first sub-area  30  including the compressor  12  and the condenser  14  and a second sub-area  32  including the evaporators  26 . 
     The wall  28  may for example be a housing, within which the components to be cooled are located, i.e. for example the battery housing. The compressor  12  and the condenser  14  are here arranged outside the housing, whereas the evaporators  26  are arranged within the housing. 
       FIG. 2  shows a lateral sectional view of the coupling unit  16 . The expansion valve  20  is mounted on the right-hand side of the wall  28  and is thus positioned in the first sub-area  30  of the refrigerant circuit  10 . 
     The expansion valve  20  has two connections  34  which are not described in more detail and by means of which the expansion valve  20  is connected to the refrigerant lines  11  which lead to the compressor  12  and to the condenser  14 . 
     On the left-hand side of the expansion valve  20 , a first coupling connection  36  which is associated with a refrigerant feed  25  of the evaporator  26  and a second coupling connection  38  which is associated with a coolant return  27  from the evaporators  26  are located. 
     Each of the two coupling connections  36 ,  38  penetrates the wall  28  and protrudes into the expansion valve  20 . Between the first and second coupling connections  36 ,  38  and the expansion valve  20 , an annular seal  40  is respectively provided, which in the embodiment shown in  FIG. 2  are each positioned in a groove of the first and the second coupling connections  36 ,  38 . 
     A further seal  42  is provided between the wall  28  and the expansion valve  20  and seals the transition between the first sub-area  30  and the second sub-area  32  of the refrigerant circuit  10 . 
     The two coupling connections  36 ,  38 , which form for example a type of pipe connecting sleeve, are fastened to the expansion valve  20  and to the wall  28  by means of a common fastening device  44 . The common fastening device  44  comprises a common pressing part  46  and a fastening element  48  that is accessible for connecting and disconnecting the fastening device  44  from a side of the expansion valve  20 , which faces away from the coupling connections  36 ,  38 . 
     In the embodiment shown, the pressing part  46  engages positively in a lateral indentation  50  of the first and second coupling connections  36 ,  38  and is pulled by the fastening element  48  in the form of a screw from the side of the expansion valve  20 , which is associated with the first sub-area  30  of the refrigerant circuit  10 , in the direction of the expansion valve  20 , as a result of which the coupling connections  36 ,  38  and the wall  28  are pressed against the expansion valve  20 . The pressing part  46  presses against a contact surface that is respectively formed by lateral projections  52  of the first and second coupling connections  36 ,  38 , and moreover is supported (at the top and the bottom in relation to  FIG. 2 ) on the wall  28 . 
     In the embodiment shown, the lateral indentation  50  and the lateral projection  52  are each formed to be symmetrically annular. It is also possible for the lateral indentation  50  or the lateral projection  52  to extend only over sub-areas of the circumference of the first and/or the second coupling connection(s)  36 ,  38 . In this way, for example, an additional fastening of the coupling connection  36 ,  38  in the circumferential direction on the expansion valve  20  and/or the wall  28  is made possible. 
     The coupling connections  36 ,  38  are axially fixed through the lateral indentation  50  and the lateral projection  52  via the pressing part  46 . 
     The axial direction is to be understood to mean in each case the direction of the corresponding refrigerant line  11 . 
     The first coupling connection  36  is implemented as a refrigerant distributor  22 . Since in this way, the refrigerant distributor  22  is positioned very closely to the throttle point  18  of the expansion valve  20 , there will only be an insignificant segregation of the gas-liquid mix of the refrigerant after the throttle point  18  up to the refrigerant distributor  22 . Thus the refrigerant is evenly distributed over the sub-lines  24  that are connected to the refrigerant distributor  22 . The distribution is essentially dependent on the spatial layout of the refrigerant distributor  22  or on external forces, for example on acceleration forces in a vehicle. 
     In the embodiment of the refrigerant distributor  22  as shown in  FIG. 2 , the refrigerant line  11  has a first hydraulic diameter immediately downstream of the throttle point  18 , which diameter is reduced to a second hydraulic diameter shortly before the branching point of the sub-lines  24 . In the area of the reduced hydraulic diameter, the flow rate of the refrigerant is increased as a result of the Venturi effect. 
     The throttle point  18  is positioned in the expansion valve  20  in such a way that the refrigerant line  11  extends at an angle of 90° to the flow direction of the throttle point  18 . The refrigerant flowing through the throttle point  18  at a high velocity impinges vertically on the wall of the refrigerant line  11  and the refrigerant is intensely mixed. 
       FIG. 3  shows a top view of the coupling unit  16  according to the sectional plane shown in  FIG. 2 , wherein, however, the coupling unit  16  is shown in a lying position and not in a standing position as in  FIG. 2 . The expansion valve  20  which is located behind the wall  28  is shown in dotted lines. In the wall  28 , two circular recesses  54  are provided, through which the coupling connections  36 ,  38  protrude. 
     As can be readily seen in this view, the pressing part  46  is formed as a comb-shaped plate that can be laterally pushed onto the coupling connections  36 ,  38 . 
     The pressing part  46  bears both against the lateral projections  52  of the coupling connections  36 ,  38  and against the wall  28 . 
     In the pressing part  46 , two threaded bores  56  for two fastening elements  48 , which are here implemented as screws, are provided which allow the pressing part  46  to be axially clamped against the wall  28  and the coupling connections  36 ,  38 . 
       FIG. 4  shows a detailed view of the fastening means and the seals of the coupling unit  16 . The first or second coupling connection  36 ,  38  has a lateral projection  52  and a lateral indentation  50 . The pressing part  46  positively protrudes into the lateral indentation  50  of the coupling connection  36 ,  38 , as a result of which the pressing part  46  is fixed in an axial direction relative to the coupling connection  36 ,  38 . 
     The pressing part  46  bears both against the lateral projection  52  and against the wall  28  and thus fixes the expansion valve  20 , the wall  28  and the coupling connection  36 ,  38  relative to each other. A first seal  40  is provided between the coupling connection  36 ,  38  and the expansion valve  20 . In the embodiment shown in  FIG. 4 , the seal  40  is located in a recess in the housing of the expansion valve  20 . 
     A second seal  42  is provided between the wall  28  and the expansion valve  20 . The seal  42  is positioned in a groove in the wall  28 , with the depth of the groove determining a maximum compression of the seal  42 . In this way, an optimal sealing function of the seal  42  is ensured. 
     The seal  42  surrounds an edge of the expansion valve  20 , with the seal bearing against both surfaces of the edge, thus enhancing the sealing function. 
     The seal  42  may be a separate component which is inserted in the groove of the wall  28  or may be integrally moulded to the wall  28 , and said wall  28  with the seal  24  may for example be produced by way of a two-component injection moulding process. 
     In the embodiments shown, both the first and the second coupling connections  36 ,  38  are formed as a one-piece component that is produced separately by turning or milling, which component is connected to the refrigerant lines  11  or to the sub-lines  24 . 
     Alternatively it is possible for the first or second coupling connection  36 ,  38  to be made by moulding the coolant return and/or the coolant feed. 
       FIG. 5  shows a detailed view of a refrigerant distributor  22  according to a further embodiment. The refrigerant distributor is formed as a joint component with the coupling connection  36 . 
     On the right-hand side of the refrigerant distributor  22 , a refrigerant line  11  having a constant hydraulic cross section is formed. The outside of the refrigerant distributor  22  has a groove in which the first seal  40  is disposed, as well as a lateral projection  52  and a lateral indentation  50  for fixing the refrigerant distributor  22  in the axial direction by means of the pressing part  46  of the coupling unit  16 . 
     The division of the refrigerant line  11  into several sub-lines  24  takes place at a cusp  58  of the refrigerant distributor. 
     The hydraulic cross section of the refrigerant line  11  from the throttle point  18  to the cusp of the refrigerant distributor  22  is between 3 and 8 mm. 
     The length of the refrigerant line  11  between the throttle point  18  of the expansion valve  20  and the cusp  58  of the refrigerant distributor  22  amounts to 2 to 10 times the hydraulic cross section of the refrigerant line  11 . 
     As can be seen in  FIG. 6 , the refrigerant distributor  22  divides the refrigerant line  11  into four sub-lines  24 . Preferably, the refrigerant distributor  22  is mounted on the expansion valve in such a way that respectively two sub-lines  24  are located on the same level  60 . When installing the system in a vehicle, it can also be considered here that the two sub-lines  24  will be on the same level  60  even in the case of a pitch motion of the vehicle. 
     The refrigerant distributor  22  shown in  FIG. 5  and in  FIG. 6  is formed in such a way that the refrigerant liquid mass flow is the same in all sub-lines  24 . Alternatively, for example, different cross sections may be provided for the various sub-lines  24 , as a result of which a desired ratio of the refrigerant liquid mass flow of different sub-lines may be adjusted. 
       FIG. 7  shows a cooling device  62  for a vehicle propulsion battery having several cooling bases  64  which are connected to a total of four parallel-connected refrigerant sub-lines  24 . The coupling unit  16  allows the integration of the cooling device  62  in a battery housing, said cooling bases  64  each corresponding to an evaporator  26  of the refrigerant circuit  10  and said cooling bases  64  being disposed within a battery housing which forms the wall  28  of the coupling unit  16 . Since the fastening element  48  of the fastening device  44  is accessible from the side of the expansion valve  20  that is opposite the coupling connections  36 ,  38 , it becomes possible to connect and disconnect the fastening device  44  from a side that is outside of the housing of the battery. In this way, in particular the expansion valve  20  can be replaced without having to open the battery housing. 
       FIG. 8  shows a further embodiment of a coupling unit  16 . The embodiment differs from the embodiment shown in  FIG. 2  in that the common fastening device  44  including the fastening element  48  and the pressing part  46  clamps exclusively the coupling connections  36 ,  38  and the expansion valve  20  together. Thus, the wall  28  is not connected to the expansion valve  20  via the common fastening device  44 . 
     The fastening element  48  protrudes through the expansion valve  20  and pulls the pressing part  46  and thus the projections  52  in the direction of valve  20 , in order to clamp the parts together to form a unit. 
     Instead of a seal  42  between the expansion valve  20  and the wall  28  (cp.  FIG. 2 ), a seal  66  is here provided between the wall  28  and the refrigerant feed  25  as well as the refrigerant return  27 . The seal  66  comprises a sealing body  68  which is made from a substantially rigid material and several sealing elements  70 ,  72  which are attached to the sealing body  68  on the edge thereof. 
     Two internal annular sealing elements  70  surround the refrigerant feed  25  and the refrigerant return  27  and thus provide a seal between the sealing body  68  and the refrigerant feed  25  and the refrigerant return  27 , respectively. 
     An outer annular sealing element  72  is disposed on the outer perimeter of the sealing body  68  and provides a seal between the sealing body  68  and the wall  28 . The outer sealing element  72  bears here on the inner side against the cylindrical section  74  of the wall  28 . 
     The sealing elements  70 ,  72  are preferably integrally moulded on the sealing body  68  by way of two-component injection moulding. 
     The internal and external sealing elements  70 ,  72  are made from several beads which are arranged in an axial direction next to each other and are made from an elastically deformable material. 
     Alternatively, also separate sealing elements  70 ,  72  may be provided, which are for example positively fixed to the sealing body  68 . 
     Since the seal  66  is connected neither to the expansion valve  20  nor to the wall  28 , the seal  66  can move relative to the wall section  74  and/or to the refrigerant feed  25  and the refrigerant return  27 . The movement of the seal  66  is limited on the side of the expansion valve  20  by the pressing part  46  and on the side of the wall  28  by a wall stop  76 . In this way, an axial play between the three components, namely the wall  28 , the seal  66  and the expansion valve  20  (including the refrigerant feed  25  and the refrigerant return  27 ) becomes possible, whilst at the same time a good seal is ensured between the refrigerant lines  11  and the wall  28 . 
     The wall  28  forms a pot-shaped housing in which the expansion valve  20  is accommodated. The pot-shaped housing is immediately followed by a further wall  78  that forms, for example, the housing of a vehicle battery. 
     As can be readily seen in both  FIGS. 9 and 10 , the outer sealing element  72  surrounds the outer circumference of the sealing body  68 . Two inner sealing elements  70  surround the two pipes of the refrigerant feed  25  and the refrigerant return  27 . On the side of the seal  66  that faces towards the expansion valve  20  ( FIG. 9 ), the comb-shaped pressing part  46  is positioned on the refrigerant feed  25  and the refrigerant return  27 . 
     The sealing body  68  is realized in two pieces and is separated along a plane through the centres of the refrigerant feed  25  and the refrigerant return  27 . In this way, the sealing body  68  may simply be mounted to the refrigerant lines  11 . On the side of the seal  66  that faces away from the expansion valve  20  ( FIG. 10 ), the two pieces ( 80 ,  82 ) of the sealing body  68  are connected to each other by way of a screw connection  84 . The screw connection  84  allows a simple disconnection of the two pieces  80 ,  82  of the sealing body  68 , for example for replacing the seal  66 . 
     Of course, also other connections between the two pieces  80 ,  82  of the sealing body  68  may be provided. 
     It is also possible for the sealing body  68  to be divided into even more pieces, for example into three pieces, with the centre piece being located between the refrigerant feed  25  and the refrigerant return  27  and the two other pieces being respectively located on opposite sides of the refrigerant feed  25  and the refrigerant return  27 .