Abstract:
The invention relates to a circuit for conducting an electric current, by an electrical component, between a vehicle battery and an electrical network component that can be connected to the vehicle battery. The circuit includes a first electrical line segment and a second line segment that is separated from the first line segment by a spacer. The line segments are connected to one another by the electrical component.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the U.S. National Phase Application of PCT International Application No. PCT/EP2012/064709, filed Jul. 26, 2012, which claims priority to German Patent Application No. 10 2011 079 966.4, filed Jul. 28, 2011, the contents of such applications being incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a circuit for conducting an electric current between a vehicle battery and an electrical network component which can be connected to the vehicle battery via an electrical element and a vehicle having the circuit. 
       BACKGROUND OF THE INVENTION 
       [0003]    In order to implement measurements of an electric current output to an electrical consumer by an electrical energy source in a motor vehicle, a current sensor can be connected in series between the electrical energy source and the electrical consumer. Such a current sensor is known, for example, from DE 10 2011 078 548 A1, is incorporated by reference. 
         [0004]    Current sensors need to be connected in series between the electrical energy source and the electrical consumers. 
       SUMMARY OF THE INVENTION 
       [0005]    An aspect of the present invention consists in improving this connection of the current sensors in series between the energy source and the consumer. 
         [0006]    This is achieved by the features of the independent claims. Preferred developments are the subject matter of the dependent claims. 
         [0007]    The invention proposes a circuit for conducting an electric current between a vehicle battery and an electrical network component which can be connected to the vehicle battery via an electrical element, which comprises a first electrical line section and a second line section, which is separated from the first line section via a spacer, wherein the line sections are connected to one another via the electrical element. 
         [0008]    In the context of the invention, the electrical element can be any desired element which can be connected between the vehicle battery and the electrical network component. Thus, the electrical element can be, for example, the current sensor mentioned at the outset, a filter for improving electromagnetic compatibility (referred to as EMC), a protective diode and/or a temperature sensor, which monitors the ambient temperature for the protection of other electrical elements. In this case, the current sensor can be used for current measurement, charge current regulation, current rise limitation or as a current switch. The current sensor and the corresponding applications can be implemented unidirectionally or bidirectionally. 
         [0009]    In the same way, the electrical network component, beside the vehicle battery, can be any desired electrical element such as an electrical energy source in the form of a generator, a socket outlet or another battery or an electrical consumer, such as, for example, a vehicle electrical distribution system or an electric motor. 
         [0010]    The cited circuit is based on the consideration that the electrical element could be connected directly between the vehicle battery and the electrical network component. However, this consideration is based on the knowledge that the electrical connection would at the same time also have to take on the mechanical strength between the vehicle battery and the electrical network component. Therefore, with the cited circuit, it is proposed to make electrical contact with the electrical element between the vehicle battery and the other electrical network component via line sections, which are kept at a predefined distance from one another via a spacer. In this way, mechanical loads which are introduced, for example, as a result of heat work, vibrations or other mechanical disturbances onto the circuit can be absorbed by the spacer, with the result that the electrical connection between the line sections and the electrical element is protected against mechanical loads and therefore against mechanical stresses. 
         [0011]    By virtue of the cited circuit, the electrical element is electrically connected between the vehicle battery and the other electrical network component permanently and continuously, as a result of which the electrical connection of the vehicle battery and the other electrical network component can be made more reliable. 
         [0012]    In a development of the cited circuit, the line sections are interlocked with one another in labyrinth-like fashion. With this development of the cited circuit, the line sections are interleaved with one another in order to achieve a fixed mechanical coupling of the line sections via the spacer and a low level of thermal expansion of the connecting zones between the line sections, which is produced as a result of the now very thin line sections. 
         [0013]    In an additional development of the cited circuit, the labyrinth-like interlocking of the line sections is resilient. In this way, the line sections can absorb a remaining proportion of mechanical loads themselves and thus avoid a situation whereby the electrical contact-making points of the electrical element with which electrical contact is to be made via the line sections are also mechanically loaded outside the labyrinth-like interlocking. 
         [0014]    In another development of the cited circuit, the spacer is formed from a premold material. A premold material is understood to mean a material which, in a melted state of aggregation, is inserted between the two line sections and then cures between the two line sections. Such premold materials can be, for example, thermosetting plastics and thermoplastics. The premold material makes it possible for the spacer to be formed with very precise dimensions, with the result that the spacer does not brace the two line sections mechanically against one another unnecessarily in a state free of mechanical loads between the two line sections. 
         [0015]    In a preferred development of the cited circuit, the premold material envelops a surface of the electrical line sections in such a way that an opening for making electrical contact with the electrical element remains free on the line sections. In this way, further improved mechanical fixing of the electrical line sections and therefore a zone which is even more free of mechanical stresses can be provided for the electrical element and its electrical connection to the electrical line sections. 
         [0016]    In another development of the cited circuit, a distance between the first line section and the second line section is dependent on a breakdown field strength of the spacer. The dependence is in particular in this case designed in such a way that the lower the breakdown field strength of the spacer, the greater the distance. Particularly preferably, in this case the distance is selected to be large enough for it to be possible for no electrical flashover to occur between the line sections. 
         [0017]    The line sections can consist of copper, aluminum, iron, nickel and alloys thereof. Ostensibly, the temperature coefficient and the thermal conductivity are important in the choice. 
         [0018]    In yet another development of the cited circuit, the contact areas on the line sections for making contact with the electrical element are coated. Coating materials which can be selected can include metals or metal alloys used to assist in the electrical contact-making of the electrical element to the corresponding line section. Such metals or metal alloys can be alloys which are based on copper or a mixture of copper and nickel, such as Cu—Ni—SN, Cu—Sn, Cu—Ni—Au, Cu—Ni—Pd—Au or Cu—Ag. The contact areas on the electrical line sections can in this case be cleaned prior to the electrical contact-making, in particular with CO 2  by means of irradiation, with plasma or with a laser. For the contact-making itself, the electrical elements can be applied to the electrical line sections by means of sintering, adhesive bonding or soldering. 
         [0019]    In a preferred development of the cited circuit, the cited circuit comprises the electrical element, which is covered by a protective compound. The protective compound, which can also be in the form of glob-top or silicone gel, protects and insulates the electrical element permanently, in particular against moisture and impurities which could result in electrical malfunctioning of the electrical element. 
         [0020]    In a particularly preferred development of the cited circuit, the line sections are mounted on a component part mount, referred to as leadframe. A plurality of circuits can be mounted simultaneously on this leadframe and can therefore be mass-produced, wherein the individual circuits ultimately then only need to be separated from one another by being severed. 
         [0021]    An aspect of the invention also specifies a vehicle which comprises
       a vehicle battery,   an electrical network component which is connected to the vehicle battery, and   one of the cited circuits, which is connected between the vehicle battery and the electrical network component.       
 
         [0025]    An aspect of the invention also specifies a method for producing a circuit for conducting an electric current between a vehicle battery and an electrical network component which can be connected to the vehicle battery via an electrical element, which comprises the steps of arranging a first electrical line section and a second electrical line section with a gap with respect to one another, introducing a spacer into the gap, and bridging the gap having the spacer with an electrical element, with the result that the electrical element electrically connects the first and second line sections to one another. 
         [0026]    The cited production method can be extended by production method steps which analogously realize the features of the cited circuit in accordance with the dependent claims. 
         [0027]    The above-described properties, features and advantages of this invention and the way in which these properties, features and advantages are achieved will become clearer and more easily understandable in connection with the description below relating to the exemplary embodiments which are explained in more detail in connection with the drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  shows a schematic view of circuits which are mounted on a leadframe; 
           [0029]      FIG. 2  shows a schematic view of one of the circuits shown in  FIG. 1 ; 
           [0030]      FIG. 3  shows a schematic sectional view of part of the circuit shown in  FIG. 2 ; 
           [0031]      FIG. 4  shows a schematic sectional view of part of the circuit shown in  FIG. 2 ; 
           [0032]      FIG. 5  shows a side view of the circuit shown in  FIG. 2 , and 
           [0033]      FIG. 6  shows an alternative side view of the circuit shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    Identical technical elements are provided with the same reference symbols in the figures and are only described once. 
         [0035]    Reference is hereby made to  FIG. 1 , which shows a schematic view of circuits  2  which are mounted on a leadframe  4 . 
         [0036]    In the present embodiment, the circuits  2  are intended to be used for current sensors  6 , yet to be described, which can be connected in series between a vehicle battery (not illustrated in any more detail) and an electrical consumer (not illustrated in any more detail) or between the vehicle battery and an electrical connection (not illustrated in any more detail) for charging the vehicle battery. In  FIG. 1 , only some of the current sensors  6  have been provided with a reference symbol, for reasons of clarity. The current sensors  6  are intended to measure the current output by the vehicle battery or the current feeding the vehicle battery, on the basis of which a state of charge of the vehicle battery can be detected, which state of charge can in turn be used for energy management of the vehicle battery. 
         [0037]    In the present embodiment, the leadframe  4  has two main rails  8 , from which electrical busbars  10 , also referred to as webs  10 , protrude at right angles, wherein contact is made between said electrical busbars and electrical connections  12 ,  14 ,  16  (yet to be described) of the circuits  2 . Index holes  18  are formed on the main rails  8 , with it being possible to detect the longitudinal dimensions of the circuits  2  by measurement technology using said index holes in order to transport and separate the circuits  2  in automated fashion. 
         [0038]    In  FIG. 1 , each circuit has three line sections  20 ,  22 ,  24 , which are mechanically and electrically isolated from one another by an electrically insulating gap  25 . In  FIG. 1 , only the gap  25  of a circuit  2  has been provided with a reference symbol, for reasons of clarity. In this case, one of the electrical connections  12 ,  14 ,  16  is formed at each line section  20 ,  22 ,  24 . In the present embodiment, a first of the electrical connections  12  is intended to be connected to the abovementioned vehicle battery, with the result that the first connection  12  will be referred to below as battery connection  12 . A second of the electrical connections  14  is intended to be connected to the abovementioned electrical consumer, with the result that the second connection  14  will be referred to below as consumer connection  14 . A third of the connections  16  is intended to be connected to the abovementioned electrical connection, with the result that the third connection  16  will be referred to below as electrical connection  16 . The line sections  20 ,  22 ,  24  on which the battery, consumer and electrical connections  12 ,  14 ,  16  are formed correspondingly will also be referred to below using corresponding nomenclature. 
         [0039]    Hereinafter, two current sensors  6  on each circuit  2  bridge two of the line sections  20 ,  22 ,  24 , with the result that an electrical current can flow either between the battery connection  12  and the consumer connection  14  or between the battery connection  12  and the electrical connection  16 . In this way, a vehicle battery connected to the battery connection  12  can be discharged and possibly charged via the consumer connection  14  and charged and possibly discharged via the electrical connection  16 . 
         [0040]    In the present embodiment, the current sensors  6  are mounted on one of the line sections  20 ,  22 ,  24  and electrical contact is also made between said current sensors and said line section and between said current sensors and the respective further line section  20 ,  22 ,  24  via a bond  26 . In  FIG. 1 , only one of the bonds  26  has been provided with a reference symbol, for reasons of clarity. The current sensors  6  can have any desired design, but the current sensors  6  are particularly preferably in the form of active shunts, which are known from DE 10 2011 078 548 A1. For reasons of brevity, reference is made to this document for further details regarding these active shunts. 
         [0041]    Furthermore, the line sections  20 ,  22 ,  24  can also connect EMC and ESD capacitors  28  and protective switching elements  30 , which can be in the form of, for example, a protective diode, a protective capacitor or a protective varistor. The EMC capacitors are used for filtering undesired signal components from the current to be conducted and thus improve electromagnetic compatibility and resistance to electrostatic discharges. In  FIG. 1 , only some of the EMC capacitors  28  and the protective switching elements  30  have been provided with a reference symbol, for reasons of clarity. 
         [0042]    Finally, temperature sensors  32  which can be provided for detecting a temperature of the circuit  2  in order to introduce suitable protective measures in the event of overheating of the circuit  2  can be arranged on the battery line section  12  and/or one of the other line sections  14 ,  16 . In  FIG. 1  only some of the temperature sensors have been provided with a reference symbol, for reasons of clarity. In addition to this monitoring function, the temperature sensors can also be used for characteristic correction of the electrical elements, such as, for example, field-effect transistors contained in the current sensors  6 . 
         [0043]    The above-described gap  25  is thus necessary for current measurement, for increasing electromagnetic compatibility (EMC) and resistance to electrostatic discharges (ESD) and for implementing the protective switching elements  30 . It therefore needs to be ensured that the individual line sections  12 ,  14 ,  16  do not have any electrical contact with one another. 
         [0044]    On the other hand, the individual line sections  20 ,  22 ,  24  also require a certain mechanical hold with respect to one another, however. Otherwise, the bonding wires  26 , the EMC capacitors  28  and the protective switching elements  30  would be subjected to excessively severe mechanical tensile loading, which could release the electrical contact between these elements or damage the elements themselves and could thus render the circuit  2  inoperative. In addition, the line sections  20 ,  22 ,  24  themselves can also be stressed and transfer these stresses to the electrical elements which are mounted on said line sections, such as the current sensors  6  and the temperature sensors  32 , which in this case could also result in release of the electrical contact-making or damage to the elements themselves. 
         [0045]    In order to circumvent these disadvantages, in the present embodiment it is therefore proposed to interlock the line sections  20 ,  22 ,  24  with one another in labyrinth-like fashion and to embed said line sections in a premold compound  34 , with the result that the premold compound  34  holds together the individual line sections  20 ,  22 ,  24  in an inflexible manner. 
         [0046]    This will be explained in more detail below with reference to  FIG. 2 , which shows a schematic view of one of the circuits  2  shown in  FIG. 1  without population with elements, such as the current sensors  6 , the bonding wires  26 , the EMC capacitors  28  and the protective switching elements  30  and the temperature sensors  32 . 
         [0047]    As can be seen from  FIG. 2 , the battery line section  20  has labyrinths  36 , into which the arms  38  engage, which arms are formed correspondingly on the consumer line section  22  and on the current line section  24 . The arms  38  in this case have the same labyrinth-shaped profile as the labyrinth  36 , but are narrower, with the result that the electrically insulating gap  25  remains between the line sections  20 ,  22 ,  24 . By virtue of the arms  38  engaging in the labyrinths  36 , the line sections  20 ,  22 ,  24  are interlocked and therefore interleaved in labyrinth-shaped fashion. 
         [0048]    In order to maintain the mechanical stability between the line sections  20 ,  22 ,  24 , at least the gap  25  is cast with the premold compound  34 . In the present embodiment, however, all of the line sections  20 ,  22 ,  24  are coated with the premold compound  34 , wherein openings  40  remain into which the electrical elements mentioned above and shown in  FIG. 1  are inserted and can be brought into contact with the line sections  20 ,  22 ,  24 . This will be discussed in more detail at a later juncture. In  FIG. 2 , only some of the openings  40  have been provided with a reference symbol, for reasons of clarity. 
         [0049]    If, in the design shown in  FIG. 2 , two of the line sections  20 ,  22 ,  24  are subjected to tensile or compressive loading with respect to one another, this results in the material of the premold compound  34  in the gap  25  being compressed at one point, while it is spread out at another point. In this way, two different counterforces applied by the premold compound  34  act counter to the tensile or compressive loading, as a result of which the line sections  20 ,  22 ,  24  are held in mechanically fixed fashion in relation to one another at their relative positions. 
         [0050]    As a result of the fact that the premold compound  34  additionally also extends over the surface of the line sections  20 ,  22 ,  24 , the line sections  20 ,  22 ,  24  are prevented from rotating inwards, resulting in surface tensions which could then be transferred to the abovementioned elements. Thus, an electrically and mechanically stable circuit  2  is provided which also meets very high demands in terms of reliability, as are expected in automotive engineering, for example. 
         [0051]    Reference is made to  FIG. 3 , which shows a schematic sectional view of part of the circuit  2  shown in  FIG. 2 . 
         [0052]      FIG. 3  shows part of the battery line section  12  and the current line section  24 , which are electrically isolated by the gap  25 , wherein the gap  25  is bridged electrically via the current sensor  6  and the bond  26 , with the result that an electrical current can flow between the two line sections  20 ,  24  via the current sensor  6 . 
         [0053]    In the present embodiment, the current sensor  6  and the bonds  26  are surrounded by a protective compound  42  consisting of a glob-top or silicone gel material, which protective compound protects the current sensor  6  and the bonds  26  from the ingress of moisture and other impurities. 
         [0054]    The line sections  20 ,  22 ,  24  can be encapsulated by injection molding with the premold material  34 , for example, with the result that some of the premold material  34  passes through the gap  25 . Therefore, a relatively small accumulation of premold material  34  is located beneath the bond  26  in the region of the gap  25 , and this accumulation provides additional anchoring for the line sections  20 ,  22 ,  24  in the premold compound  34 . 
         [0055]    Reference is made to  FIG. 4 , which shows a schematic sectional view of part of the circuit shown in  FIG. 2 , in which electrical contact is made with a protective switching element  32  between the battery line section  12  and the current line section  16 . 
         [0056]    As can be seen in  FIG. 4 , in the present embodiment, electrical contact is made directly between the protective switching element  32  and the line sections  20 ,  24  without a further bond. Therefore, it is necessary to ensure that there is no accumulation of premold material  34  beneath the protective switching element  32 . This can be ensured either by virtue of the fact that the gap is covered during encapsulation by injection molding of the line sections  20 ,  24  in the opening  40  or the premold material  34  is removed after encapsulation by injection molding of the line sections  20 ,  24  in the opening  40 . 
         [0057]    Reference is made to  FIG. 5 , which shows a side view of the circuit  2  shown in  FIG. 2  encapsulated by injection molding with the premold material  34 , wherein the electrical busbars  10  shown in  FIG. 1  are electrically connected to the circuit  2 . 
         [0058]    As can be seen in  FIG. 5 , the connections  12 ,  14 ,  16 , of which the battery connection  12  and the consumer connection  14  are shown by way of example in  FIG. 5 , can be bent back. In this way, the connections  12 ,  14 ,  16  can extend mechanically at an angle to the circuit  2 , with the result that the connections do not introduce any mechanical loads, for example as a result of thermal expansion, into the circuit  2 . 
         [0059]      FIG. 6  shows an alternative example for the design of the connections  12 ,  14 ,  16  so as to permit mechanical expansion at right angles to the circuit  2 . In  FIG. 6 , the connections  12 ,  14 ,  16  are folded, as a result of which the connections can be pushed together and can thus themselves absorb mechanical expansions in the direction of the circuit  2 .