Patent Publication Number: US-2023141760-A1

Title: Heat Retarding Arrangement with a Phase Change Material for an Electric Vehicle

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date under 35 U.S.C. § 119(a)-(d) of German Patent Application No. 102021129227.1, filed on Nov. 10, 2021, and European Patent Application No. 22205138.5, filed on Nov. 2, 2022. 
     FIELD OF THE INVENTION 
     The invention relates to a heat retarding arrangement for passively cooling an electric conductor at or in an electric vehicle. 
     BACKGROUND 
     In electric vehicles, in particular in their electric charge and/or drive circuits, and in connection arrangements, such as charging connectors, high currents can flow or should flow. High currents are desired to permit a quick charging of the vehicle batteries or the provision of sufficient power for operating the vehicle. However, high currents usually lead to a heating of the electric conductors. This can be counteracted by an increase of the conductors’ cross-sections. The increase of the conductors’ cross-sections, however, is only practicable within certain limits. Larger conductor cross-sections mean an increased material consumption and thus increased costs. Moreover, increased conductor cross-sections of conductors on the vehicle side lead to an increased vehicle weight. This can in turn lead to a reduction of the range. 
     An active cooling for electric conductors is known. However, the active cooling systems need energy themselves and are moreover technically sophisticated and therefore expensive. It is therefore desirable to provide a solution by which electrical vehicles can be charged and/or operated with high currents without risking the overheating of an electric conductor. 
     SUMMARY 
     A heat retarding arrangement includes a phase change material. The heat retarding arrangement is attachable at or in an electric conductor and passively cools the electric conductor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which: 
         FIG.  1    is a perspective view of a heat retarding arrangement according to an embodiment configured as a cable clip at a cable; 
         FIG.  2    is a sectional perspective view of the cable clip of  FIG.  1   ; 
         FIG.  3    is a perspective view of the cable clip of  FIG.  1    showing an abutment section; 
         FIG.  4    is a sectional plan view of a cable clip and a cable according to an embodiment; 
         FIG.  5    is a sectional plan view of a cable clip and a cable according to another embodiment; 
         FIG.  6    is a schematic view of a heat retarding arrangement configured as a cable clip with temperature sensors; 
         FIG.  7    is a schematic view of an arrangement with heat retarding arrangements according to another embodiment; 
         FIG.  8    is a sectional side view of a heat retarding arrangement according to an embodiment in a charging port; 
         FIG.  9    is a sectional side view of a heat retarding arrangement according to another embodiment in a charging port; 
         FIG.  10    is a sectional side view of a heat retarding arrangement according to an embodiment at an electric conductor; 
         FIG.  11    is a sectional side view of a heat retarding arrangement according to an embodiment in a screw of a bolted connection; 
         FIG.  12    is a detail sectional view of the screw of  FIG.  11   ; 
         FIG.  13    is a sectional side view of the screw of  FIG.  11   ; 
         FIG.  14    is a heat transfer arrangement according to a first embodiment for fixing a bus bar to a vehicle; 
         FIG.  15    is a detail sectional view of the heat transfer arrangement of  FIG.  14   ; 
         FIG.  16    is a heat transfer arrangement according to a second embodiment for fixing a bus bar to a vehicle; 
         FIG.  17    is a detail sectional view of the heat transfer arrangement of  FIG.  16   ; 
         FIG.  18    is a heat transfer arrangement according to a third embodiment for fixing a bus bar to a vehicle; 
         FIG.  19    is a detail sectional view of the heat transfer arrangement of  FIG.  18   ; and 
         FIG.  20    is another detail sectional view of the heat transfer arrangement of  FIG.  18   . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The invention will be described in more detail below by way of example embodiments with reference to the drawings. The combination of features represented by way of example in the embodiments can be supplemented by further features according to the above illustrations corresponding to the properties of the heat retarding arrangement according to the invention for a certain case of application. Moreover, also according to the above illustrations, individual features can be omitted in the described embodiment if the effect of this feature is not relevant in a case of application. In the drawings, the same reference numerals are always used for elements having the same function and/or the same structure. 
     A first embodiment of a heat retarding arrangement  2  configured as a cable clip  1  is described with reference to  FIGS.  1  to  3   . The cable clip  1  serves to fasten a cable  3  comprising an electric conductor  4  to an electric vehicle  5  or a part  7  of an electric vehicle  5 . The electric vehicle  5  or the part  7  of the vehicle  5  are only indicated in a dashed line in  FIG.  1   . The part  7  can be, for example, a part of the chassis, the car body, the drive, a battery housing, or another vehicle component. The electric conductor  4  can be, for example, an inner conductor of the cable  3 . 
     The electric vehicle  5  can be a battery-electric vehicle, a fuel-cell vehicle, or else a partially electrically operated vehicle, for example a hybrid vehicle or a plug-in hybrid vehicle. The electric conductor  4  can be part of a cable, for example a battery cable on the vehicle side, i. e. a cable which directly or indirectly connects a charging port on the vehicle side with an energy storage, in particular a battery. As an alternative, the conductor  4  or the cable comprising the conductor can also be part of a high-voltage on-board power supply which, for example, connects the energy storage with the drive unit. Further examples of electric conductors are bus bars, contact elements and sections of contact elements, in particular contact elements in charging ports or charging pistols. 
     The part  7  of the vehicle  5  to which the heat retarding arrangement  2 , in particular the cable clip  1 , can be attached can be part of the chassis, the car body, the drive, a battery housing, or another component. The attachment to a battery housing can be advantageous since batteries or their housings often have a cooling system themselves in electric vehicles. Therefore, the heat arising in the cable can be supplied to the cooled battery housing via the heat retarding arrangement  2 . 
     The heat retarding arrangement  2  can be configured to be attachable at or in a conductor  4 . Here, it can be directly or indirectly attached at the conductor  4 . An indirect attachment can result from the heat retarding arrangement  2  being attached, for example, at a cable that contains the electric conductor  4 . 
     The cable clip  1  for fastening exactly one cable  3  is also represented only by way of example. As an alternative, the cable clip  1  can also be configured to simultaneously fasten a plurality of cables  3 . 
     The cable clip  1  may be arranged near a component  9  that is connected with the cable  3 . The component  9  can be a pin-and-socket connector  11 , as represented by way of example. As an alternative, other components  9  are also conceivable, in particular a charging port on the vehicle side, a drive unit, a battery or accumulator of the vehicle, a controller or other things. 
     In an embodiment, a distance  13  of the cable clip  1  to the component  9  shown in  FIG.  1    amounts to only a few centimeters, and in an embodiment less than 10 cm. Thereby, heat developed in the component  9  can be conducted via the cable  3  into the cable clip  1  and through the latter to the vehicle  5 . 
     The cable  1  has a cable receiving section  15  configured to receive the cable  3 . The cable receiving section  15  can include a passage opening  17  through which the cable  3  can be guided. 
     The cable clip  1  moreover includes an abutment section  19  configured for the abutment against a part  7  of the vehicle  5 . The cable clip  1  is formed in the abutment section  19  which can represent one end of the cable clip  1 , for example complementary to the part  7  of the vehicle  5  where the cable clip  1  is to be attached. 
     In the embodiment represented by way of example, the cable clip  1  is flatly configured in the abutment section  19 . This means it can be used for the abutment against a plane surface. As an alternative, other embodiments are also possible. The flat design has the advantage that heat from the cable clip  1  can be conducted to the vehicle  5  over a large abutment surface. The abutment surface  21  in the abutment section  19  may substantially correspond to the cross-sectional area  23  of the cable clip  1 . In other words, the cross-section of the cable clip  1  can continuously extend into the abutment section  19 . 
     The cable clip  1  comprises a heat accumulator body  25  with a phase change material  27 , as shown in  FIG.  2   . The phase change material  27  is located within the heat accumulator body  25 . The heat accumulator body may have a plurality of spaces  29  or cavities  29  in which the phase change material  27  is located. The spaces  29  can extend continuously through the heat accumulator body  25  or be locally limited. In an embodiment, the heat accumulator body  25  is formed of a material which includes a frame structure  31 . The frame structure  31  can span the spaces  29 . A frame structure  31  can be formed, for example, from a foamed material. By the heat accumulator body  25 , additional mass is moreover admitted to a cable received in the cable clip  1  by which vibrations in the cable can be attenuated. 
     The phase change material  27  can be configured such that a phase change, for example from the solid to the liquid or from the liquid to the gaseous phase, is accomplished when the temperature of the electric conductor  4  reaches predetermined limits. Due to the phase change, a cooling of the phase change material  27 , and thereby also of the electric conductor  4  at or in which the heat retarding arrangement  2  is disposed, is effected. The cooling achieved thereby can be sufficient to be able to maintain a certain intensity of current for an extended period. During a cooling of the phase change material  27 , a reversed phase transition can take place so that the phase change material  27  returns to its original state. The heat of the conductor  4  is thereby intermediately stored or buffered. The heat retarding arrangement  2  can be alternatively referred to as heating retarding arrangement or as thermal accumulator arrangement. The heat retarding arrangement  2  can here operate according to the principle of a PCM device. The heat retarding arrangement  2  can thus retard the heating of the electric conductor  4 . By the solution according to the invention, an active cooling of the electric conductor  4  can be omitted. 
     The heat retarding arrangement  2  can operate, in particular if it is attached in a conductor  4 , according to the principle of a heat pipe. At a point where the heat retarding arrangement  2  is heated, a phase transition, also referred to as phase shift or phase change, can take place for the phase change material  27  as of a defined temperature, for example, from the solid state to the liquid state or from the liquid state to the gaseous state. In the process, thermal energy is withdrawn from the phase change material  27 . At another point of the heat retarding arrangement, a reversed phase transition can take place. For example, the liquid phase change material can solidify again, or a gaseous phase change material can condense again and return to the liquid state. In the process, the thermal energy is released again. By a transport of the phase change material  27  within the heat retarding arrangement  2 , for example by capillary forces, the liquid phase change material  27  can return again to the original place. Thereby, a heat retarding arrangement  2  with a phase change material can be permanently operated passively as a cooling element or at least as a thermal conductor. By the embodiment as a heat pipe, the heat is therefore not only retarded but also carried off from the place where it arises. 
     Due to the heat retarding or cooling effect of the heat retarding arrangement  2 , it is connected with those conductors or cables that probably heat up due to the current flow and where a heat development is not desired at least as of a certain degree. This can be the case in particular in cables where the heat development does not only lead to inefficient charging, but also to the charging current having to be reduced for safety reasons. 
     The phase change material  27  can contain only, for example, paraffin and/or sodium. Other materials or combinations of materials are also possible. 
     The principle of the PCM device is not only advantageous for cooling a cable received in the cable receiving section  15  by a phase transition of the phase change material  27  from solid to liquid or liquid to gaseous, but also offers altogether a good heat conduction and can conduct heat from the cable receiving section  15  to the abutment section  19 . 
     In an embodiment, the heat retarding arrangement  2  is configured to be attached at a part of the vehicle  5 . The heat retarding arrangement  2  can not only buffer the heat of the conductor  4 , but also discharge at least a portion of the heat to the vehicle  5  by forwarding the heat to the part of the vehicle  5  where it is attached. The vehicle  5  can thus serve as a heat sink. 
     The temperatures at which the phase transitions take place can be defined by a suited material selection of the material for the heat accumulator body  25  and for the phase change material  27  and by the pressure prevailing inside the heat accumulator body  25 . In case of a phase change material  27  which undergoes, during the operation of the cable clip  1 , phase transitions from the solid to the liquid phase and vice versa, the condensation of the phase change material  27  may be effected near the cable receiving section  15 , and the solidification near the abutment section  19 . In case of a phase change material  27  which undergoes, during the operation of the cable clip  1 , phase transitions from the liquid to the gaseous phase and vice versa, evaporation is correspondingly effected near the cable receiving section  15 , and condensation near the abutment section  19 . 
     As an alternative, channels as spaces  29  in which the phase change material  27  is located can also pass through the heat accumulator body. A further alternative can be that the heat accumulator body  25  consists of a composite material which contains the phase change material  27  as a component. 
     The heat accumulator body  25  may have a multi-piece design, in particular a two-piece design. In the embodiment shown in  FIG.  2   , the heat accumulator body  25  includes two half bowls  33  and  35  which can be arranged one lying against the other. Between the half bowls  33  and  35 , there is the cable receiving section  15  with the passage opening  17 . 
     In particular in an embodiment with a multi-piece heat accumulator body  25 , the cable clip  1  can comprise a housing  37  in which the heat accumulator body  25  is accommodated. The housing  37  can be formed of a plastic, a metal, in particular aluminum, or another material. As an alternative, other materials, for example, composite materials, ceramics, silicone containing materials or others, are also possible. A housing of plastic has the advantage that the housing can be manufactured quickly and inexpensively. A housing of metal has the advantage that, depending on the metal, it intrinsically has a high thermal conductivity and can thereby contribute to heat conduction and also to the dissipation of heat to the surrounding area. A metallic housing may be formed of a light metal or a light metal alloy. In an embodiment, the housing  37  is formed of aluminum or an aluminum alloy. 
     A further alternative can naturally be that the cable clip  1  is formed without housing  37 . The housing  37  can be provided with at least one passive cooling structure  39  (indicated in a dashed line in  FIG.  2   ), in particular with a cooling fin  41 . The cooling fin  41  can be formed at the housing  37 . The latter can be the case in particular in a housing of a metal, for example, aluminum. The at least one cooling structure  39  can dissipate heat to the surrounding area, in particular to the surrounding air. As an alternative, the at least one passive cooling structure  39  can also be part of the heat accumulator body  25 . The housing  37  can then extend around this cooling structure or expose it. 
     To securely fasten the two parts, or the half bowls  33  and  35  of the heat accumulator body  25 , the housing  37  may include a plurality of locking elements configured as locking hooks  43  which can engage with locking recesses  45  in the half bowls  33  and  35  configured complementarily to it, and can secure them in the housing  37 . For example, initially, the half bowl  33  can be inserted into the housing  37  to such an extent that the locking hooks  43  are arranged in the locking recesses  45 . Subsequently, the cable  3  can be inserted so that it is arranged in the cable receiving section  15 . Finally, the second half bowl  35  can be inserted. Since both half bowls  33  and  35  are each provided with a conduit-like recess  47  or  49 , respectively, which together form the passage opening  17  in an assembled state, the cable  3  is held between both half bowls  33  and  35  in the cable clip  1  in the assembled state. 
     To fasten the cable clip  1  at the vehicle  5 , and thereby indirectly fasten the cable  3  at the vehicle  5 , the cable clip  1  may have at least one fastening element  51 . The fastening element  51  can be configured to fasten the heat retarding arrangement  2  to the vehicle  5 , for example by a threaded joint, a locking, or an adhesive joint. In the embodiment represented by way of example, the fastening element  51  is a flange  53 . The flange  53  is provided with a plurality of passage bores  55 . Fastening parts, for example screws or clips, can be guided through them to hold the cable clip  1  at the vehicle  5 . 
     To improve the heat conduction between the heat accumulator body  25  and the vehicle  5 , or to ensure a continuous abutment of the cable clip  1  at the vehicle  5 , the cable clip  1  includes a heat conducting element  57  which is preferably arranged at the abutment section  19 . The heat conducting element  57  can be a heat conducting pad, a layer of heat conducting adhesive, a layer of heat conducting paste, or another suited element. 
     The housing  37  can be opened in the abutment section  19  to have the heat accumulator body  25  abut directly or, via the heat conducting element  57  indirectly, against the vehicle  5 . As an alternative, the housing  25  can also be closed in the abutment section  19 . This can be the case, for example, with a housing  37  of a metal. A closed housing can be advantageous if the heat retarding arrangement  2  does not comprise a solid heat accumulator body  25  and if it has to be ensured that liquid or gaseous phase change material does not leak. If the cable clip  1  is provided with a heat conducting element  57 , it can be arranged outside at the housing  37  at the abutment section  19 . The heat conducting element  57  may be deformable plastically and/or elastically. Thereby, during assembly, it can be pressed into spaces between the cable clip  1  and the part  7  of the vehicle  5  where the cable clip  1  abuts, and seal these spaces in a heat conducting manner. 
     To fasten a heat conducting element  57 , it can include, for example, fastening elements  59  projecting towards the cable receiving section  15 , for example elastically deformable locking hooks  61  which project through passage openings  63  in the housing  37 , in particular in the flange  53 , and are secured against slipping out by a thickened end  65 . As an alternative, the heat conducting element  57  can also be glued onto the rest of the cable clip  1 , or be fastened thereto in another suited manner. 
     At least one further heat conducting element  58  (indicated in a dashed line in  FIG.  2   ) can be arranged in the cable receiving section  15  to contribute to the heat conduction between a cable  3  in the cable receiving section  15  and the heat accumulator body  25 . 
     Below, reference is made to  FIG.  4   . In  FIG.  4   , a heat retarding arrangement  2  configured as a cable clip  1  is only indicated, wherein the cable clip  1  can in particular correspond to the embodiment described with reference to  FIGS.  1  to  3   . The cable clip  1  and the cable  3  together form an arrangement  64 . The representation shows a section which corresponds to the sectional axis marked with A-A in  FIG.  1   . A cable  3  is also shown in a sectional representation. 
     The cable  3  has an inner conductor  67 , an inner insulation  69  surrounding the inner conductor  67 , a shield  71  surrounding the inner insulation  69 , and an outer insulation  73  surrounding the shield  71 , as shown in  FIG.  4   . In this embodiment, the heat accumulator body  25  abuts against the outer insulation  73 . This embodiment is advantageous because no changes have to be made to the cable  3 . This can facilitate the assembly of the cable clip  1 . However, the fact that heat generated in the inner conductor  67  has to pass through a plurality of layers of the cable  3  before it reaches the heat accumulator body  25  can here also have a negative effect. 
     An alternative embodiment of an arrangement comprising a cable clip  1  and a cable  3  will be described below with reference to  FIG.  5   . To keep the description short, only the differences to the embodiment described with reference to  FIG.  4    will be discussed. In the arrangement  66 , the cable  3  does not have any outer insulation  73 , at least in the section  70  where it passes through the cable clip  1 . In an embodiment, it substantially is a cable  3  as described with reference to  FIG.  4   , however, the outer insulation  73  is removed in the section  70  where it extends through the cable clip  1 . The heat accumulator body  25  of the cable clip  1  consequently directly abuts against the shield  71 . 
     This arrangement permits a better heat conduction from the inner conductor  67  into the heat accumulator body  25  since the outer insulation  73  is missing. Moreover, the heat accumulator body  25  in direct contact with the shield  71  can contribute to the electromagnetic shielding and interference suppression, in particular if the heat accumulator body  25  is formed of a suited material, in particular an electrically conductive one. 
     The arrangement  66  can, as an alternative to the above-described embodiment, comprise a heat retarding arrangement  2  which is not configured as a cable clip  1 , instead of the cable clip  1 . 
     Below, a further advantageous embodiment of a cable clip  1  and a further advantageous arrangement  75  will be briefly discussed. The cable clip  1  can be structured as the cable clips  1  described above. The arrangement  75 , too, can, as an alternative to the cable clip  1 , comprise a heat retarding arrangement  2  which is not configured as a cable clip  1 . The difference to the above-described embodiments of the cable clip  1  is that the heat accumulator body is provided with two temperature sensors  77  which are embedded in the material of the heat accumulator body  25  spaced apart from each other, as shown in  FIG.  6   . Both temperature sensors  75  are connected with a control unit  79  in a data transmitting manner. The cable clip  1  forms the arrangement  75  together with the control unit  79 . 
     The control unit  79  can be configured to control a current flow through a cable  3  arranged in the cable receiving section (only represented in a dashed line in  FIG.  6   ). By the data received from the temperature sensors  77 , the temperature flow within the heat accumulator body  25  can be determined. In particular, a difference measurement of the temperatures through the two sensors  77  can be performed. 
     In an embodiment, the control unit  79  is connected with a storage unit, a non-transitory computer-readable storage medium, which stores at which temperatures a phase transition takes place in the phase change material or in a heat accumulator body  2  including the phase change material  27 . On the basis of the knowledge of an imminent phase transition, the control unit  79  can control the charging current. Since thermal energy is dissipated during the first phase transition, for example from solid to liquid or liquid to gaseous, the charging current can be correspondingly high since the overheating of the conductor or other components of the vehicle  5  can still be prevented. 
     By the data obtained from the temperature sensors  77 , it can be possible to predict a phase transition of the phase change material  27  located in the heat accumulator body  25  and to correspondingly adjust the current flow through the cable  3 . If such a calculation shows, for example, that the temperature in the heat accumulator body  25  has not yet reached a phase transition temperature, one can do without reducing the current flow through the cable  3 , or the current flow through the cable  3  can even be increased because it is known that the phase transition in the phase change material  27  has a cooling effect on the heat accumulator body  25  and thus indirectly on the cable  3 . 
     By this embodiment, the maximally possible charging current during the charging of an electric vehicle can be predicted by calculation and exhausted without reaching a dangerous temperature trail above admissible limits and thus risking to overheat the conductor and components connected therewith. 
     Below, two further advantageous arrangements each comprising a heat retarding arrangement  2  configured as a cable clip  1  will be briefly described with reference to  FIG.  7   .  FIG.  7    schematically shows a vehicle  5  from above. 
     An arrangement  81  comprises a charging port  83  on the vehicle side, a cable  3 , and a cable clip  1 . The charging port  83  is here a further example of a component  9 . The cable  3  as a battery cable can connect, for example, the charging port  83  with traction batteries. 
     The charging port  83  can extend from a region outside a vehicle  5  into the interior of the vehicle  5 . The cable  3  is connected to the charging port  83  in a current-transmitting manner. A cable clip  1  which is to connect the cable  3  with a part  7  of the vehicle  5  may be arranged at a distance  13  to the charging port  83  which may be less than 10 cm. In this manner, the cable clip  1  can indirectly remove heat from the charging port  83  via the cable  3 . As part  7  of the vehicle, the car body is represented only by way of example. Of course, the cable clip  1  can also be attached to any other interior part of the vehicle  5 . 
     A further cable clip  1  by which the cable  3  is fastened to the vehicle  5  is also represented only by way of example. The vehicle  5  can be provided with any number of cable clips  1  to secure the cable  3  sufficiently against movements, in particular vibrations, and to dissipate heat from the cable  3 . 
     A further arrangement  87  represented in  FIG.  7    comprises a heat retarding arrangement  2  configured as a cable clip  1 , a part  7  of the vehicle  5 , optionally the complete vehicle  5 , and the cable  3 , wherein the cable  3  is received in the cable receiving section  15  of the cable clip  1  and the cable clip  1  abuts against the part  7  of the vehicle  5  with its abutment section  19 . 
     In  FIG.  8   , an arrangement  88  is shown wherein a heat retarding arrangement  2  according to the invention is arranged in an electric conductor  4 . The electric conductor  4  is a contact element  90  which can be part of a charging port  83  of the vehicle  5 . The contact element  90  is connected with a bus bar  92  in an electrically conductive manner so that the contact element  90  and the bus bar  92  together form an electric conductor  4 . There is a cavity  93  in the contact element  90  in which the heat retarding arrangement  2  is accommodated. 
     In the simplest case, the heat retarding arrangement  2  only comprises the phase change material  27  in this arrangement. The phase change material  27  can be, for example, filled or placed in the cavity  93 , and the cavity  93  can be subsequently sealed. To this end, one end of the cavity  93  that is originally open to the outside can be sealed to the outside with a cap  95 . 
     As an alternative, the heat retarding arrangement  2  can also include a housing  37  in which the phase change material  27  is accommodated. The heat retarding arrangement  2  with the housing  37  can be formed, for example, as an insert for the cavity  93 . For assembly, the heat retarding arrangement  2  can be pushed, for example, into the cavity  93 . 
     Below,  FIG.  9    will be briefly discussed. Here, too, a heat retarding arrangement  2  according to the invention is used for passively cooling a contact element  90  of a charging port  83 . The heat retarding arrangement  2  comprises the phase change material  27  and a rubbery-elastic housing  37 . The electric conductor  4 , consisting of the bus bar  92  and the contact element  90 , is provided with a receptacle  91 . The phase change material  27  is received partially within the receptacle  91  and partially within the housing  37 . 
     A wall  97  in the electric conductor  4  defining the receptacle  91  and the housing  37  form a common cavity  99  in which the phase change material  27  is accommodated. Due to the rubbery-elastic design of the housing  37 , the housing  37  can compensate volume changes of the phase change material  27 . Volume changes can in particular be caused by the phase transitions in the phase change material. 
     Below,  FIG.  10    will be discussed in which a further arrangement  101  with a heat retarding arrangement  2  according to the invention is represented. The arrangement  101  also comprises a contact element  90  of a charging port  83 , wherein the contact element  90  is connected with a bus bar  92  in an electrically conductive manner. The heat retarding arrangement  2  according to the invention is here arranged to abut against the bus bar  92  and does not necessarily contact the contact element  90 . 
     The arrangement at the bus bar  92  can facilitate assembly and/or make sense if there is not sufficient installation space at the contact element  90 . By the contact element  90  being electrically conductively connected with the bus bar  92 , depending on the selection of the employed conductive materials, it is usually also connected with the bus bar  92  in a heat conducting manner. Heat generated in the contact element  90  can therefore be conducted to the heat retarding arrangement  2  via the bus bar  92 . The heat retarding arrangement  2  is arranged in the shown embodiment on the bus bar  92  at a small distance to the contact element  90 . The distance may be only a few centimeters, for example maximally 10 cm. 
     The heat retarding arrangement  2  of this embodiment also has a rubbery-elastic housing  37 . This can be the case, for example, if the housing  37  consists of silicone material. A housing  37  expandable in a rubbery-elastic manner can expand or contract to follow a volume change of the phase change material  27  during a phase transition. It can be prevented thereby that an excess or negative pressure arises in the housing  37  by which the housing  37  becomes leaky. Another advantage of a rubbery-elastic housing  37  is the increased overall volume of the phase change material  27  that can be accommodated. 
     In contrast to the embodiment described with reference to  FIG.  9   , the housing  37  is here, however, closed all around. The heat retarding arrangement  2  can be considered as a kind of pad which can be attached to the bus bar  92 . The housing  37  has an inner space  103  in which the phase change material  27  is accommodated. As in the embodiment described with reference to  FIG.  9   , the rubbery-elasticity of the housing  37  can absorb volume changes of the phase change material  27 . 
     The heat retarding arrangement  2  can be, for example, glued to the bus bar  92 ; in an embodiment, with a heat-conducting adhesive. As an alternative or in addition, the heat retarding arrangement  2  can be held at the bus bar  92  by suited external fastening devices, for example locking elements or tie wraps. 
     In particular in case of the fastening by external fastening devices, between the heat retarding arrangement  2  and the bus bar  92 , at least one heat conducting element can be arranged between the bus bar  92  and the heat retarding arrangement  2  for a better heat transfer. The heat conducting element can in particular be a layer of heat conducting paste or a heat conducting pad. The above-mentioned heat conducting adhesive is also considered as heat conducting element. 
     The heat retarding arrangement  2  can be configured as a screw  105  for interconnecting two electrical conductors  4 . This type of connection, that is also known as bolted connection, is shown in  FIGS.  11  to  13   . 
     The screw  105  is configured to connect a conductor  4 , which can be part of a cable  3 , to another conductor. The screw  105  has a screw head  107  for driving the screw  105  and for pressing the conductor  4  against the other conductor. The screw head  107  may be electrically insulated for providing touch protection. 
     Between the conductor  4  and the other conductor, one or more intermediate pieces  109 , such as a sleeve or a bushing, may be arranged. In order to produce a pressing force and to fixate the screw  105 , the screw  105  is provided with a screw thread  111  at an end that is opposite to the screw head  107 . At the end of the screw  105  that is provided with the screw thread  111 , the screw  105  may further be provided with an electrically insulated tip  113 . The insulated tip  113  may increase the safety when mounting the screw  105 . 
     Typically, the screw  105  itself only plays a minor role for conducting a current. Instead, the screw  105  is intended to mechanically fixate the electrically conductive parts with each other. However, the screw  105  also heats up when being in contact with hot electrically conductive parts, such as the conductor  4  or the intermediate piece  109 . 
     In order to reduce the heat in the screw  105  and the conductors, the screw  105  can be provided with at least one cavity  93 . Inside the cavity  93 , phase change material  27  can be arranged. The cavity  93  for the phase change material  27  can be arranged at different positions in the screw  105 . In the embodiment shown in  FIG.  12   , the cavity  93  is arranged close to the screw head  107 . The cavity  93  can be formed during the manufacturing process of the screw  105  in the region of the screw head  107 . Afterwards, the cavity  93  can be filled with phase change material  27 . Finally, the cavity  93  can be closed with a cap  95  or other elements. 
     In  FIG.  13   , an arrangement is shown that differs from the arrangement described above with respect to  FIG.  12   . Here, the cavity  93  extends at the opposite end of the screw  105 . The cavity  93  opens from the tip of the screw  105  into the material of the screw  105 , thus extending in the region of the screw thread  111 . 
     The cavity  93  may be formed during manufacturing of the screw  105  when an opening  115  for receiving parts of the insulated tip  113  is formed. After forming the opening  115  and the cavity  93 , the cavity  93  may be filled with phase change material  27 . The cavity  93  may be closed with a cap  95 . Afterwards, the insulating tip  113  can be inserted into the opening  115  in order to fixate the same to the screw  105 . In the alternative, the cap  95  may be omitted if the insulated tip  113  is sufficient for closing the cavity  93  when arranged inside the opening  115 . 
     In the following, further arrangements are described that can benefit from the advantages of the heat retarding arrangement  2  according to the invention. In the following, a heat transfer arrangement  117  is described with respect to  FIGS.  14  and  15   . 
     In  FIG.  14   , two heat transfer arrangements  117  are shown. For the sake of brevity, only one of the heat transfer arrangements  117  is described in the following. Just by way of example, the bus bars  92  shown in  FIG.  14    can be connected to a relay  119 . 
     The heat transfer arrangement  117  is intended to connect a conductor  4 , in particular a bus bar  92 , to a solid structure, in particular to a part  7  of a vehicle  5 . The heat transfer arrangement is intended to connect the bus bar  92  in an electrically insulating manner to the part  7 , but, at the same time, to allow heat to be transferred from the bus bar  92  to part  7 . 
     The heat transfer arrangement  117  comprises a hold down device  121  that can be arranged on top of the bus bar  92  and to receive the bus bar  92  at least in parts. The term “on top” refers to a side of the bus bar  92  that is opposite to the part  7 , to which the bus bar  92  is attached by the arrangement  117 . 
     In order to improve the connection between the hold down device  121  and part  7  of the vehicle, a protrusion  123  can be formed in part  7  as a counterpart to the hold down device  121 . The bus bar  92  can be arranged on top of the protrusion  123 . The hold down device  121  can be arranged on top of the bus bar  92 . Thereby, the bus bar  92  can be received between the protrusion  123  and the hold down device  121 . 
     The hold down device  121  may have a receptacle  125  for receiving the bus bar  92  in a way that leaves only one side  127  of the bus bar open for being in contact to part  7 . The hold down device  121  may be fixated via screws  59  to part  7 . In order to electrically insulate the bus bar  92  form part  7 , an intermediate layer  129  may be arranged between the bus bar  92  and part  7 . 
     The intermediate layer  129  may be an electrically insulating material with a high thermal conductivity. The intermediate layer  129  may be formed as a plate between the bus bar  92  and part  7 , as a foil, which is at least partially wrapped around the bus bar  92  or as a coating on the surface of the bus bar  92 . 
     Just by way of example, a foil  131  is indicated by dashed lines in  FIG.  15   , the foil  131  extending around the circumference of the bus bar  92 . The foil  131  does not necessarily need to cover the whole surface of the bus bar  92 . This is shown in  FIG.  15   , where a region on top of the bus bar  92  is not covered by the foil  131 . 
     In the arrangement described above, the hold down device  121  can comprise phase change material  27 . However, this is not mandatory. The heat transfer arrangement  2  for fixating the bus bar  92  to the vehicle  5  does not necessarily need to comprise the phase change material  27 . Any one of the adapter, the hold down device  121  and the intermediate layer  129  may comprise a phase change material  27  or may be made of a phase change material  27 . 
     Just by way of example, a cavity  93  containing phase change material  27  is shown in the cross-sectional view of  FIG.  15   , As already mentioned, this is only optional. The phase change material  27  may improve the heat transfer away from the bus bar  92 , in particular at those sections of the bus bar  92  that are not in direct contact with part  7 . 
     Subsequently, the heat may be transferred by the hold down device  121  to part  7 . Additionally or in the alternative, the intermediate layer  129  may comprise or may be made of phase change material  27 . As a further alternative, a further layer may be provided between the bus bar  92  and part  7  that provides phase change material  27  for heat retardation. 
     In the following, a second embodiment of the heat transfer arrangement  117  is described with respect to  FIGS.  16  and  17   . For the sake of brevity, only the differences to the embodiment described with respect to  FIGS.  14  and  15    are described. The second embodiment of the heat transfer arrangement  117  can be advantageous in a case in which a part  7  is not provided with a protrusion  123 . 
     In order to allow the bus bar  92  to be connected to part  7  in a satisfactory manner, namely heat conducting, but electrically insulating, the heat transfer arrangement  117  comprises an adapter  133  that may serve for the same purpose as the protrusion  123  described with respect to the first embodiment. The bus bar  92  is arranged between the hold down device  121  and the adapter  133 . 
     In order to fixate the hold down device  121  and the adapter  133  to each other, the adapter  133  may be provided with latching grooves  135  on two opposing sides for receiving latching hooks  137  of the hold down device  121 . The latching grooves  135  may extend parallel with a longitudinal direction  136  of the bus bar  92 . 
     The adapter  133  may be made of an electrically insulating material. However, this is not mandatory. The adapter  133  may be made from a metal material, in particular aluminum, in order to improve the heat transfer from the bus bar  92  to part  7 . 
     In particular in a case in which the adapter  133  is made of a metal, an intermediate layer  129  may be provided between the bus bar  92  and the adapter  133 . The intermediate layer  129  may be a foil  131  wrapped around the bus bar  92 . 
     As also in the first embodiment, the second embodiment of the heat transfer arrangement  117  may be provided with a phase change material  27 . As already mentioned above, the hold down device  121  and/or the intermediate layer  129  may be provided with phase change material  27 . Furthermore, the adapter  133  may provided with phase change material  27 , in particular inside at least one cavity  93  formed in the adapter  133  (indicated by dashed lines in  FIG.  17   ). 
     Now, reference is made to  FIGS.  18  to  20   , in which a third embodiment of a heat transfer arrangement  117  is shown. Again, only the differences to the embodiments shown before are described in detail. The third embodiment of the heat transfer arrangement  117  is basically similar to the second embodiment except for two cooling channels  139  extending through the adapter  133 . 
     The cooling channels  139  may extend parallel with a longitudinal direction  136  of the bus bar  92 . The cooling channels  139  can be used for actively cooling the adapters  133 . To do so, the cooling channels  139  may be part of a cooling circuit through which a coolant flows in order to transfer heat away from the adapter  133 . At the ends of the cooling channels  139 , connecting pieces  141  can be provided for facilitating the connection of the cooling channels  139  to other parts of a cooling circuit, such as tubes. The third embodiment of the heat transfer arrangement  119  may optionally be provided with phase change material  27 .