Abstract:
The present invention provides a fan installation for a cooling system of a motor vehicle, comprising at least two fans which respectively have an electric fan motor arranged in a separate housing and a fan wheel which can be driven by the fan motor. The fan installation also comprises a control unit for operating the fan motors. The invention provides for an improved fan installation with a simple and cost-effective design, which is achieved by arranging the control unit in the housing of one of the fans for operating both fan motors.

Description:
[0001]    The present disclosure relates to the subject matter disclosed in international application No. PCT/EP01/09918 of Aug. 29, 2001, which is incorporated herein by reference in its entirety and for all purposes.  
         BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a fan installation for a cooling system of a motor vehicle, comprising at least two fans which respectively have an electric motor disposed in a separate housing and a fan wheel which can be driven by said motor, and comprising a control unit for operating the fan motors.  
           [0003]    Fan installations of this type are known from the prior art. They are normally used to supply large-area radiators in a motor vehicle with the necessary cooling air, in particular when an increased cooling performance is required.  
           [0004]    In fan installations of this type, the fans are normally disposed in front of or behind the radiator, in order to produce the air flow through the radiator. Furthermore, the fans are driven by one or two control units which are disposed separately in the engine compartment.  
           [0005]    The invention is based on the object of improving a fan installation of the generic type in such a way that this is constructed as simply as possible and as cost-effectively as possible.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the invention, in a fan installation of the type described at the beginning, this object is achieved in that the control unit is disposed in the housing of one of the fans and operates both the fan motor disposed in this housing and the fan motor of the other fan.  
           [0007]    The advantage of the solution according to the invention is to be seen in the fact that with this solution the control device to be disposed separately in the engine compartment is dispensed with, and therefore one device fewer has to be mounted in the engine compartment, so that in particular in the case of restricted spatial conditions, there is a gain with regard to the space required.  
           [0008]    Furthermore, by disposing the control unit in the housing of one of the fans, the number of lines may also be simplified, since only one feed line for feeding the fan system has to be laid to one fan, and a supply line from this fan to the other fan.  
           [0009]    Furthermore, a further advantage of the solution according to the invention is to be seen in the fact that with the disposal of the control unit in the housing of one of the fans, defined conditions for the cooling of the control unit can also be achieved in a simple way, so that all the problems relating to the cooling of an additional control device disposed separately in the engine compartment are dispensed with.  
           [0010]    In addition, the control unit may advantageously be integrated into the housing of the one fan, without the volume of the latter increasing to a noticeable extent, so that a considerable gain in space in the engine compartment of the motor vehicle can therefore be achieved.  
           [0011]    Finally, by means of the integration of the control unit into the housing of the one fan, an improvement with regard to electromagnetic compatibility can additionally be achieved, since all the components which may be responsible for interference in the vehicle electrical system, such as fan motors and control unit, are combined as compactly as possible and can therefore be shielded better and therefore, overall, have a lower interference potential in the motor vehicle.  
           [0012]    A particularly advantageous solution provides for the fan installation to comprise a harness which can be connected to both fans and has a plug-in connection comprising a supply connection and an external connection.  
           [0013]    By means of this one harness, it is therefore possible for the total of three cables in the case of the solution known hitherto to be replaced by two connectors in each case, so that a considerable simplification is already possible on the part of the supply lines.  
           [0014]    It is particularly advantageous in this case if the harness can be connected to each of the fans via a plug-in connection.  
           [0015]    The harness is preferably constructed in such a way that it comprises a connecting line running between the fans and having a feed line.  
           [0016]    In principle, a single feed line would be sufficient if a good ground connection is possible between the fans via the usual installation situation in the motor vehicle.  
           [0017]    However, in order to obtain the most advantageous electrical solution possible with regard to interference removal, provision is preferably made for the connecting line also to have a ground line in order advantageously to achieve the best possible ground connection between the control unit and the fan motor which is not disposed in the same housing as the control unit.  
           [0018]    Furthermore, it is particularly advantageous if the harness has a supply line which runs from the fan provided with the control unit to the plug-in connection and comprises a feed line and an input line.  
           [0019]    In principle, it would likewise be unnecessary here to provide a separate ground line. With regard to interference immunity. However, it is likewise beneficial if the supply line has a ground line.  
           [0020]    A particularly simple solution provides for the supply line and the connecting line to form a coherent harness and therefore for it to be possible for both lines to be connected, via a common plug-in connection, to the fan provided with the control unit and, via a further plug-in connection, to the other fan, so that overall a harness of this type for the fan installation according to the invention has to have a total of only three plug-in connections, namely the common plug-in connection and in each case one plug-in connection for producing the connection to each of the fans, it being possible for a connection with the control unit to be produced at the same time in the case of the fan provided with the control unit.  
           [0021]    With regard to the construction of the control unit, no specific statements were made in connection with the previous explanation of the fan installation according to the invention. For example, a particularly simple and therefore cost-effective solution provides for the control unit to comprise a common output stage for the operation of all the fan motors, so that therefore all the fan motors can be operated via the same output stage, preferably in a parallel circuit.  
           [0022]    This solution is extremely cost-effective with regard to the required components, but entails restriction, in particular in the case of monitoring these fan motors and in the case of any separate drive required.  
           [0023]    An alternative solution of the fan installation according to the invention therefore provides for the control unit to comprise a dedicated output stage for the operation of each of the fan motors, the output stages of the control unit, corresponding to the number of fan motors, likewise being disposed in the housing of one of the fans and the other fan being supplied via the harness from the end stage provided for said fan and therefore having no kind of control electronics.  
           [0024]    With regard to the cooling of the control unit, no specific statements were made in connection with the solutions described hitherto. For example, one advantageous solution provides for the control unit to be coupled thermally to a heat sink and therefore for the heat from the control unit to be dissipated via this heat sink.  
           [0025]    The heat preferably arises in this case in the output stage of the control unit, so that it is particularly beneficial if each output stage is coupled thermally with the heat sink.  
           [0026]    Preferably carried out in particular are thermal coupling of an electronic switch of the output stage with the heat sink and of a freewheel diode associated with said electronic switch.  
           [0027]    With regard to the configuration of the heat sink, no specific statements have been made hitherto. In principle, the cooling of the heat sink itself could be carried out in extremely diverse ways. In particular, however, since the heat sink is arranged on one of the fans, it is particularly beneficial if the heat sink is air-cooled.  
           [0028]    For this purpose, the heat sink is expediently provided with a ribbed heat sink, in order to achieve the greatest possible surface for the dissipation of heat to the air flow.  
           [0029]    In particular in the case of a plurality of output stages, it is expedient if each of the output stages is coupled to a dedicated ribbed heat sink, so that the heat of each of the output stages can be dissipated in a particularly efficient way.  
           [0030]    With regard to the air cooling, it would be conceivable, for example, to arrange the heat sink in such a way that the latter is disposed on an outer side of the housing or projects out of the housing and the air flow that is produced by the fan wheel and passes through the radiator flows against and cools said heat sink.  
           [0031]    However, particularly efficient cooling of the heat sink results if an air flow that can be produced by the fan wheel flows through the housing of the fan which is provided with the control unit, and the air flow flows against the heat sink. The control unit according to the invention can therefore be particularly efficiently cooled.  
           [0032]    The advantage of this solution is to be seen in the fact that the air flow which flows through the housing and which in particular also serves to cool the fan motor itself can be used for the purpose of cooling the control unit, and therefore cooling of the control unit with an air flow forced in accordance with the power of the fan is possible, so that, as a result, always defined relationships in cooling the control unit are achieved without special measures being required since, in the case of fans of this type, it is usual for the housing to be passed through in any case by a forced air flow for cooling the fan motor, so that in the case of the solution according to the invention, the result is necessarily also specific and defined cooling of the control unit without additional measures being required.  
           [0033]    Particularly expedient cooling may be achieved by the heat sink being disposed in the area of an air opening in the housing, through which the air flow passes.  
           [0034]    In this case, the air opening is preferably located in a wall region which belongs to the housing and surrounds the control unit.  
           [0035]    With regard to the construction of the control unit itself, no specific statements were made in connection with the previous explanation of the individual exemplary embodiments. For example, a particularly advantageous exemplary embodiment provides for the control unit to have a circuit board which extends in a plane running transversely with respect to the axis of rotation of the fan motor. Such a disposition of the circuit board in the housing of the fan has the great advantage that the control unit may be accommodated in a very space-saving manner in said circuit board.  
           [0036]    This solution is particularly space-saving if the circuit board bears current feeds for a commutator of the fan motor, so that no independent carrier arrangement for the current feeds for the commutator has to be provided; instead, the latter are situated directly on the circuit board and therefore can also be connected electrically to the circuit board in a simple way.  
           [0037]    Current feeds of this type can be constructed in any desired way. It is particularly beneficial if the current feeds comprise carbon brush holders disposed on the circuit board and carbon brushes which can be moved with respect to said holders.  
           [0038]    In order to dissipate the heat produced in the region of the current feeds for the commutator as advantageously as possible, provision is preferably made for the current feeds to be thermally coupled with the heat sink.  
           [0039]    Further features of the invention are the subject matter of the following description and of the illustrative representation of some exemplary embodiments. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0040]    [0040]FIG. 1 shows a plan view of a first exemplary embodiment of a fan installation according to the invention;  
         [0041]    [0041]FIG. 2 shows a schematic circuit of the first exemplary embodiment of the fan installation according to the invention;  
         [0042]    [0042]FIG. 3 shows a simplified illustration of a control unit of the first exemplary embodiment of the fan installation according to the invention, comprising circuit board and heat sink;  
         [0043]    [0043]FIG. 4 shows an external view of a housing of a fan provided with the control unit according to FIG. 3;  
         [0044]    [0044]FIG. 5 shows a section along the line  5 - 5  in FIG. 4 through the fan provided with the control unit;  
         [0045]    [0045]FIG. 6 shows an illustration similar to FIG. 2 of a circuit of the control unit of a second exemplary embodiment of a fan installation according to the invention;  
         [0046]    [0046]FIG. 7 shows an illustration similar to FIG. 3 of the control unit of the second exemplary embodiment of the fan installation according to the invention, and  
         [0047]    [0047]FIG. 8 shows an illustration similar to FIG. 4 of an external view of the housing of the fan provided with the control unit in the second exemplary embodiment of the fan installation according to the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0048]    A first exemplary embodiment, illustrated in FIG. 1, of a fan installation according to the invention for a cooling system, in particular a cooling system of a motor vehicle, comprises a first fan  10  and a second fan  20 , which are preferably mounted on a common carrier  30 .  
         [0049]    The first fan  10  comprises a first housing  12 , in which a first fan motor  14  is disposed and is used for the purpose of driving a first fan wheel  16 .  
         [0050]    The second fan  20  comprises a second housing  22 , in which a second fan motor  24  is disposed and is used for the purpose of driving a second fan wheel  26 .  
         [0051]    The fan installation according to the invention is preferably used for cooling a motor vehicle radiator, preferably one of rectangular shape, which can be covered by the carrier  30 , air being blown by the first fan  10  through a first fan opening  32  in the carrier  30 , while air is blown by the second fan  20  through a second fan opening  34  in the carrier  30 .  
         [0052]    As illustrated in FIG. 2, the first fan motor  14  and the second fan motor  24  can be operated by a common control unit  40  which, in the case of the first exemplary embodiment, has an output stage  42  which feeds both the first fan motor  14  and the second fan motor  24  connected in parallel thereto.  
         [0053]    The output stage  42  has, for example, an electronic switching transistor  44  and a freewheeling diode  46 , the electronic switch  44  being located between a feed connection  48  of the control unit  40  and feed lines  14   a  and  24   a  of the fan motors  14  and  24 , respectively, and feeding the latter in a cyclic manner, while the freewheeling diode  46  absorbs the current flow caused by the inductance of the fan motors  14  and  24  when the electronic switch  44  is switched off.  
         [0054]    The fan motors  14  and  24  are furthermore connected by ground lines  14   b  and  24   b  to a ground connection  50  of the control unit  40 .  
         [0055]    The electronic switch  44  is driven via a control line  52  by a drive unit  54  which, in turn, can be operated by a logic circuit  56 , it being possible for the drive unit  54  to be operated by the logic circuit  56  in such a way that it operates the electronic switch  44  with a pulse-width-modulated signal, the electric power absorbed by the fan motors  14  and  24  being predefineable by means of the pulse width.  
         [0056]    In this case, the logic circuit  56  can predefine, via an input line  58   a,  variables on the basis of which the parameters for defining the pulse-width-modulated signal for driving the electronic switch  44  are determined.  
         [0057]    In the first exemplary embodiment of the fan installation according to the invention, as shown in FIG. 3, the output stage  42  comprising the electronic switch  44  and the freewheeling diode  46  is disposed on a circuit board  60 , which can be inserted into the first housing  12  of the first fan  10 , the circuit board  60  bearing not only the output stage  42  but, at the same time, the drive unit  54  and the logic circuit  56 , so that the entire control unit  40  is disposed in the first housing  12  of the first fan  10 .  
         [0058]    For the space-saving accommodation of the components of the control unit  40 , the circuit board  60  is preferably so disposed in the housing  12  that it extends in a plane  61  which runs transversely with respect to an axis of rotation of the first fan motor  14 .  
         [0059]    In order also to configure the design to be as compact as possible, current feeds  62  and  64  for a commutator  66  illustrated in FIG. 5 and belonging to the first fan motor  14  are additionally provided on the circuit board  60 .  
         [0060]    Also situated on the circuit board  60  is a plug-in connection  68 , via which a connection is made both to the feed connection  48  and to the ground connection  50 , and also a connection between the output stage  42  and the second fan motor  24 , to which the feed line  24   a  and the ground line  24   b  feed, so that no kind of electronic subassembly is provided in the second housing  22  of the second fan  20 .  
         [0061]    For the purpose of cooling the control unit  40 , as illustrated in FIGS. 3 and 4, a heat sink  70  is provided, with which in particular the electronic switch  44  and the freewheeling diode  46  are thermally coupled. However, thermal coupling to the current feeds  62  and  64  and the heat sink  70  is also preferably further provided.  
         [0062]    In particular, each of the current feeds  62 ,  64  is provided with a carbon brush holder  62   a  and  64   a  disposed in a fixed manner on the circuit board  60 , and a carbon brush  62   b,    64   b  which is disposed such that it can be moved in the respective carbon brush holder  62   a,    64   a,  which carbon brushes make contact with the commutator.  
         [0063]    The heat sink  70  for its part comprises, for example, a ribbed heat sink  72 , which is preferably constructed in such a way that it can be cooled by an air flow  76  flowing into the first housing  12  through an air opening  74 , the air flow  76  flowing through the ribbed heat sink  72  and preferably also flowing through a stator  78  and a rotor  80  of the first fan motor  14  in order to cool the same.  
         [0064]    The air flow  76  preferably flows first through the ribbed heat sink  72 , then enters the fan motor  14  in a rear region  82  thereof, flows through the latter and emerges from the first fan motor  14  again from a region  84  thereof on the front side. In so doing, the air flow  76  reaches a fan pot  88  which engages over the front region  84  of the first fan motor  14  with a base  86 , the base  86  deflecting the air flow  76  and feeding it to slats  90  belonging to the fan pot  88 , which accelerate the air flow  76  in the radial direction toward an axis of rotation  92  of the rotor  80  and, on a side of the fan pot  88  facing away from the base  86 , allow it to emerge radially outside the first housing  12 .  
         [0065]    Thus, in order to produce a negative pressure in the fan pot  88 , the fan pot  88  acts on the basis of its slats  90  as a motor fan wheel which forces the air flow  76  and which represents a subarea of the first fan wheel  16 , the latter, in particular with vanes  94  disposed outside the fan pot  88 , accelerating the air which is intended to pass through the first fan opening  32  of the carrier  30 .  
         [0066]    The air flow  76  forced through the fan pot  88  is therefore used not only for the purpose of cooling the fan motor  14  in a defined and known way but, at the same time, also for the purpose, via the ribbed heat sink  72 , of cooling the heat sink  70  which, for its part, in turn cools the electronic switch  44  and the freewheeling diode  46 , which represent the power components of the end stage  42  which produce the most heat.  
         [0067]    Furthermore, the heat sink  70  is preferably further provided with a bow  96 , which runs from the ribbed heat sink  72  disposed opposite the plug-in connection  68  as far as the plug-in connection  68  and has retaining webs  98  to be supported on the circuit board  60 .  
         [0068]    The ribbed heat sink  72  and the bow  96  are preferably overall a one-piece part, to which the circuit board  60  is fixed.  
         [0069]    In particular, the control unit  14  can be inserted into the first housing in such a way that the ribbed heat sink  72  is located with outer ends  102  of its cooling ribs  100  in the air opening  74  of the first housing  12 .  
         [0070]    Furthermore, the entire control unit  40  is further covered by a housing cover  104 , which closes the entire first housing  12  in the region of an end facing away from the first fan wheel  16  and therefore also spreads over the circuit board  60  of the control unit  40 .  
         [0071]    The two fans  10  and  20 , as illustrated in FIG. 1, are preferably connected to a harness  106  which has a plug-in connector  108  which can be connected to the plug-in connection  12  which preferably projects beyond the housing  68 , has a plug-in connector  110  which can be connected to the electrical system of the motor vehicle, and has a plug-in connector  112  with which an electrical connection can be made to the fan motor  24  of the fan  20 .  
         [0072]    Here, the harness  106  has a connecting line  114  which runs from the plug-in connector  108  to the plug-in connector  112  and which, as illustrated in FIG. 2, comprises the feed line  24   a  and the ground line  24   b,  which runs from the output stage  42  to the second fan motor  24  of the second fan  20 .  
         [0073]    The harness  106  also comprises a supply line  116 , which runs from the plug-in connector  110  to the plug-in connector  108  and, as illustrated in FIG. 2, has a feed line  48   a  leading from a first supply connection  49  to the feed connection  48 , a ground line  50   a  leading from a second supply connection  51  to the ground connection  50 , and an input line  58   a  leading from an external connection  59  to an input connection  58 , the supply connections  49  and  51  and the external connection  59  being provided in the plug-in connector  110  and being capable of being connected to the connection provided for the fan installation.  
         [0074]    In a second exemplary embodiment of the fan installation according to the invention, illustrated in FIGS.  6  to  8 , those elements which are associated with those of the first exemplary embodiment are provided with the same reference symbols so that, with regard to the description of the same, reference can be made to the entire content of the first exemplary embodiment.  
         [0075]    As opposed to the first exemplary embodiment of the fan installation according to the invention, in the second exemplary embodiment of the fan installation according to the invention the control unit  40 ′ is provided with a first output stage  42   a  for the first fan motor  14  and a second output stage  42   b  for the second fan motor  24 , each of the output stages having an electronic switch  44   a  and  44   b,  respectively, and a freewheeling diode  46   a  and  46   b,  respectively, which operate in the same way as described in connection with the first exemplary embodiment.  
         [0076]    Via the control lines  52   a  and  52   b,  the electronic switches  44   a  and  44   b  can each be driven with a pulse-width-modulated signal by the common control unit  54 ′.  
         [0077]    However, in the second exemplary embodiment of the fan installation according to the invention, the feed line  14   a  and the ground line  14   b  lead to the first output stage  42   a,  and the feed line  24   a  and the ground line  24   b  lead to the second output stage  42   b  and are therefore driven separately from each other by the electronic switches  44   a  and  44   b  respectively provided for the fan motors  14  and  24 .  
         [0078]    Nevertheless, in the second exemplary embodiment of the fan installation according to the invention, the entire control unit  40 ′ is also disposed in the first housing  12  of the first fan  10 .  
         [0079]    However, in this case, the heat sink  70 ′ is respectively provided with a ribbed heat sink  72   a  and  72   b  preferably on opposite sides of the circuit board  60 , each ribbed heat sink  72   a, b  being associated with an output stage, specifically the output stage  42   a  and  42   b,  respectively, and being used in particular to cool the respective electronic switch  44   a  and  44   b  and the corresponding freewheeling diode  46   a  and  46   b.    
         [0080]    Furthermore, the drive unit  54  and the logic circuit  56  and also the current feeds  62  and  64  for the first fan motor  14  are also arranged on the circuit board  60 .  
         [0081]    The entire control unit  40  can then be inserted into the first housing  12  in such a way that the ribbed heat sinks  72   a, b  are respectively associated with air openings  74   a, b  and can be cooled by the air flow  76   a  and  76   b,  respectively, passing through these, said air flow for example entering the first housing  12  through the corresponding air openings  74   a  and  74   b  and, in the same way as described in connection with the first exemplary embodiment of the fan installation according to the invention, being forced through the fan pot  88  of the first fan wheel  16  so that cooling both of the control unit  40  and of the first fan motor  14  in the case of the first fan  10  are carried out in the same way as described in connection with the first exemplary embodiment of the first fan installation but modified to the extent that two air flows  76   a  and  76   b  enter the first housing  12  on opposite sides and then also flow through the first fan motor  14 .