Abstract:
A compact arrangement features a fan ( 42 ′), a fluid pump ( 134 ), and an electric drive motor ( 106 ). The latter has a stator ( 22 ) having a stator winding ( 118 ) that is configured to generate a rotating field. The stator ( 22 ) has associated with it a permanent-magnet external rotor ( 106 ) for driving the fan ( 42 ′), and a permanent-magnet internal rotor ( 140 ) for driving the fluid pump ( 134 ). The stator winding ( 118 ) thus drives not only the rotor ( 106 ) of the drive motor and hence the fan ( 42 ′), but also the internal rotor ( 140 ) and hence the fluid pump ( 134 ). The arrangement is very well suited for combination with a fluid cooler ( 90 ).

Description:
CROSS-REFERENCE 
       [0001]    This application is a section 371 of PCT/EP2005/09543, filed 6 Sep. 2005, and published as WO 2006-056 249-A1, claiming priority from DE 20 2004 018 458.3 of 19 Nov. 2004, both of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to an arrangement having a fan, a pump, and a drive motor. 
       BACKGROUND 
       [0003]    Arrangements of this kind have a design that requires a great deal of space. This is unfavorable in situations where little space is available, e.g. in medical or electronic devices. 
       SUMMARY OF THE INVENTION 
       [0004]    It is therefore an object of the invention to make available a novel arrangement having a fan, a pump, and a drive motor. 
         [0005]    According to the invention, this object is achieved by arranging for the rotating magnetic field created by the stator to drive both a permanent-magnet external-rotor fan motor and a permanent-magnet internal pump rotor. 
         [0006]    A space-saving arrangement is thereby achieved because the same stator drives both a permanent-magnet external rotor and, by way thereof, a fan, as well as a permanent-magnet internal rotor that in turn drives a pump. 
         [0007]    A very advantageous embodiment of the invention is to provide a magnetically transparent structural element which makes a hermetic separation of the pump rotor from the stator and the fan rotor. In this case, the stator has an additional function because it surrounds the internal rotor in the manner of a partitioning can. 
         [0008]    A further advantageous refinement of the invention is to implement the stator as a coreless winding. A coreless winding means a large air gap, but in the largely homogeneous magnetic field between the external rotor and internal rotor it is possible, with appropriate current flow, to generate a highly constant torque, with the result that such an arrangement runs quietly. 
         [0000]    The optimum type of current flow depends on the manner in which the external and internal rotor are magnetized. 
     
    
     
       BRIEF FIGURE DESCRIPTION 
         [0009]    Further details and advantageous refinements of the invention are evident from the exemplifying embodiments, in no way to be understood as a limitation of the invention, that are described below and depicted in the drawings. In the drawings: 
           [0010]      FIG. 1  is a longitudinal section through a highly schematic depiction to explain the basic principles of the invention; 
           [0011]      FIG. 2  is a depiction to explain the arrangement according to  FIG. 1 ; 
           [0012]      FIG. 3  is a depiction of a coreless winding used in  FIGS. 1 and 2 , shown in the manner usual in electrical engineering; 
           [0013]      FIG. 4  schematically depicts a preferred embodiment of the driver stage for the winding of  FIG. 3 ; 
           [0014]      FIG. 5  shows the sequence of current flow in the winding according to  FIG. 3  in combination with the circuit according to  FIG. 4 , for a rotation angle α=360° el.; 
           [0015]      FIG. 6  is a longitudinal section through a first exemplifying embodiment of an arrangement according to the present invention, looking along line VI-VI of  FIG. 7 ; 
           [0016]      FIG. 7  is a section looking along line VII-VII of  FIG. 6 ; 
           [0017]      FIG. 8  is a longitudinal section through a second exemplifying embodiment of an arrangement according to the present invention, looking along line VIII-VIII of  FIG. 9 ; 
           [0018]      FIG. 9  is a section looking along line IX-IX of  FIG. 8 ; 
           [0019]      FIG. 10  is a detailed depiction showing, for the second exemplifying embodiment, how the external rotor is mated to the stator; and 
           [0020]      FIG. 11  is an individual depiction showing, for the second exemplifying embodiment, the appearance of the internal rotor with the pump wheel, and the cover of the pump housing, before assembly thereof. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      FIG. 1  schematically depicts an arrangement  20  according to the invention. The size of the air gaps, which of course should be very small, is exaggerated for reasons of clarity. This depiction serves essentially to explain the manner of operation. The pump and fan are merely indicated. 
         [0022]    Arrangement  20  has a motor  21  comprising a stator  22 , which latter is preferably depicted as a coreless winding  23  having a plastic part  24  that surrounds a permanent-magnet internal rotor  26  in liquid-tight fashion in the manner of a partitioning can or hermetic separator and is separated from rotor  26  by an internal air gap  28 . In magnetic terms, plastic part  24  also forms part of internal air gap  28 , as does external air gap  51  (described below) because it is magnetically transparent. If winding  23  is implemented in coreless fashion, the entire interstice between internal rotor  26  and external rotor  44  constitutes, in magnetic terms, one homogeneous air gap. 
         [0023]    Internal rotor  26  drives a hydraulic machine  27 , in this case a pump wheel  30 .  FIG. 11  shows at the top a typical pump wheel that is implemented integrally with an internal rotor. Rotor  26  and pump wheel  30  are enclosed in liquid-tight fashion on the left side by plastic part  24 , and on the right side by a pump cover  32  such as the one depicted by way of example in the lower part of  FIG. 11 . Located between plastic part  24  and pump cover  32  in  FIG. 1  is a seal  34 ′ of arbitrary type. In practice, parts  24  and  32  are adhesively bonded or welded. 
         [0024]    Located in pump cover  32  in  FIG. 1  are an inlet  34  and an outlet  36  for the fluid to be pumped, e.g. oil in a motor vehicle, or cooling water, or a fluid in a medical device. Rotor  26  and pump wheel  30  are journaled, as depicted in  FIG. 1 , on the left in plastic part  24  and on the right in pump cover  32 . Another type of journaling will be described below. 
         [0025]    Plastic part  24  is mounted via radially extending struts  38 , only one of which is depicted, on an air guidance housing  40  within which fan blades  42  rotate during operation in order to transport air through this fan housing. An axial fan is depicted, but a diagonal fan or radial fan would be possible in the same fashion. Fan blades  42  are mounted on a permanent-magnet external rotor  44  that is depicted in longitudinal section and is journaled via rolling bearings  46 ′,  48 ′ on plastic part  24 . A magnetic yoke in the form of a soft iron part  46  is mounted in external rotor  44 , which part turns a ring magnet  48  that here is preferably implemented with four poles, as is internal rotor  26 . 
         [0026]    Located on the radially inner side of ring magnet  48  is a damping arrangement  50 , e.g. in the form of a short-circuit cage or a thin-walled ring of sheet copper. A damper of this kind is useful because one of the two rotors usually controls the rotating field of winding  23  via Hall sensors, and because the other rotor then normally follows this rotating field as in the case of a synchronous machine but, for example at startup, any relative motion between internal rotor  26  and external rotor  44  is damped. This prevents rotors  26  and  44  from getting out of step in a context of dynamic processes. Damping arrangement  50  is separated from stator  22  by external air gap  51 . 
         [0027]    A circuit board  52 ′ is provided to control the currents in winding  23 , on which board three Hall sensors  54  are provided in the case of a winding having three phases;  FIG. 1  depicts only one of these sensors, which in this embodiment is controlled by ring magnet  48 . 
         [0028]    Alternatively, the use of Hall sensors can also be avoided and the rotor position can be determined in sensorless fashion. In this case a circuit board  56  can be arranged externally on housing  40 , and the rotor position is then calculated by means of an algorithm, e.g. an algorithm according to EP 0 536 113 B1 and corresponding U.S. Patent RE-39076, von der Heide et al. 
         [0000]    A damper  50  proves useful in this case, and such a system can, if applicable, also be provided on internal rotor  26  or on both rotor magnets  26 ,  48 . 
         [0029]      FIG. 2  is a highly schematic section, not to scale, through the arrangement of  FIG. 1 , and  FIG. 3  shows by way of example the configuration of a suitable three-phase winding  23 . 
         [0030]    Depicted all the way at the outside in  FIG. 2  is magnetic yoke  46 , in which is located rotor magnet  48  depicted with four poles, whose four radially magnetized poles are indicated with N and S in the usual way. Rotor magnet  48  is separated by external air gap  51  from stator  22 , and the latter is in turn separated by internal air gap  28  from the four-pole internal rotor  26 . 
         [0031]    Stator  22  contains, as shown, twelve uniformly distributed conductors  1  to  12  whose connections are depicted in  FIG. 3 . Winding  23  depicted in  FIG. 3  is a four-pole, three-phase, “twelve-slot” winding with no shortening of the winding pitch. (If a stator core is not used, no slots in the usual sense are present. The use of soft ferromagnetic material in stator  22  is of course not precluded.) 
         [0032]      FIG. 3  shows the three phases U, V, and W in a depiction as if twelve uniformly distributed slots  1  to  12  were present. Phase U has two terminals u 1  and u 2 , phase V two terminals v 1  and v 2 , and phase W two terminals w 1  and w 2 . Phase U is shown as a solid black line, phase V as a dot-dash line, and phase W as a dashed line. Phase U proceeds from terminal u 1  to slot  1 , then to slot  4 , then to slot  7  and to slot  10 , and from the latter to terminal u 2 . 
         [0033]    Phase V goes v 1  to slot  3 , then to slots  6 ,  9 , and  12 , and from there to v 2 . 
         [0034]    Phase W goes from w 1  to slot  5 , then to slots  8 ,  11 , and  2 , and from there to w 2 . 
         [0035]    Further details are evident from  FIG. 3 . 
         [0036]    The twelve conductors depicted in  FIG. 2  are numbered with the same slot numbers  1  to  12  in order to facilitate comprehension. 
         [0000]    The angle α is likewise indicated. 
         [0037]    Magnet  48  of external rotor  52  and magnetic internal rotor  26  are magnetically coupled to one another, as depicted schematically in  FIG. 2  by the four flux lines  60 ,  62 ,  64 ,  66 . Pump rotor  26  and fan rotor  52  together form a magnetic flux that is four-poled with respect to air gaps  28  and  51 . The two rotors  26  and  52  are thereby positioned relative to one another, as in a magnetic coupling, in the position depicted in  FIG. 2 , a largely homogeneous magnetic flux being constituted in the air gaps. 
         [0038]    With appropriate current flow, winding  23  produces a torque on internal rotor  26  and on external rotor  52 . The total torque can be derived from the Lorenz equation as 
         [0000]        T=I*B*L*r   (1) 
         [0039]    where 
         [0040]    T=torque; 
         [0041]    I=current through a conductor; 
         [0042]    B=magnetic flux density in the space (“air gap”) between rotors  26  and  52 ; 
         [0043]    r=radius of the conductor with reference to the rotation axis of rotors  26  and  52 . 
         [0044]    For the entire arrangement with currents I 1 , I 2 , I 3  as depicted in  FIG. 3 , the motor torque T_Motor can be calculated as 
         [0000]      T_Motor=ke 1 *I 1 +ke 2 *I 2 +ke 3 *I 3   (2) 
         [0045]    where ke=motor constant. 
         [0046]    In normal operation, the angular offset between external rotor  52  and internal rotor  26  is very low, and the torque distribution over the two rotors can be calculated quite accurately by simulation. 
         [0047]    In an arrangement having a pump and a fan, it is usually the case that the pump requires more torque than the fan; the effect is as if rotor  26  were being braked, so that (referring to  FIG. 2 ) it lags slightly behind external rotor  52 , i.e. the magnetic boundaries are correspondingly shifted with respect to one another, as is readily apparent to one skilled in the art of electrical engineering. The possible relative angular offset of the two rotors is damped by damping ring  50  at the inner radius of external ring magnet  48 . If a relative motion occurs between internal rotor  26  and external rotor  52 , an electric current is then induced in damping ring  50  and counteracts any relative motion. 
         [0048]    In the context of control of the currents in winding  23 , a possible angular offset of this kind is taken into account in the ramp-ups, in order to ensure that external rotor  52  can follow internal rotor  26 . 
         [0049]      FIG. 4  shows a circuit for supplying current to winding  13  with its three phases U, V, W. The latter are each depicted with their inductive component (e.g. Lu), their resistive component (e.g. Ru), and their induced voltage (e.g. Uu), as is done in a computer simulation. (The coupling inductances, which are likewise taken into account in a simulation, are not depicted.) A delta circuit is depicted, its connection points being labeled  65 ,  67 , and  69 . 
         [0050]    A full bridge circuit  68 , often also referred to as an inverter, serves to supply current to winding  13 . This circuit obtains its current from a DC voltage source  70 , e.g. a vehicle battery or the power supply of a computer. DC voltage source  70  is connected at its negative pole to ground  71 . Its positive pole feeds a positive lead  74 , also called a DC link, via a diode  72  that prevents misconnection. A storage capacitor of, for example, 4700 μF is arranged between lead  74  and ground  71 . Said capacitor supplies the full bridge circuit with reactive power. 
         [0051]    Full bridge circuit  68  has three upper npn transistors  81 ,  82 ,  83  and three lower npn transistors  84 ,  85 ,  86 , each of which has a respective free-wheeling or recovery diode  81 ′ to  86 ′ connected antiparallel with it. 
         [0052]    The collectors of upper transistors  81 ,  82 ,  83  are connected to positive lead  74 . The emitters of lower transistors  84 ,  85 ,  86  are connected to a negative lead  78  that is connected via a measuring resistor  80  to ground  71 . Measuring resistor  80  is part of a current limiter (not depicted). 
         [0053]    The emitter of transistor  81  and the collector of transistor  84  are connected to node  65 . 
         [0054]    The emitter of transistor  82  and the collector of transistor  85  are connected to node  67 . 
         [0055]    The emitter of transistor  83  and the collector of transistor  86  are connected to node  69 . 
         [0056]    Transistors  81  to  86  are controlled by signals s 1  to s 6 , as depicted in  FIG. 4 . For example, if s 1 =1 then transistor  81  is conductive, and if s 1 =0 it is blocked. 
         [0057]      FIG. 2  shows an angle α that, in the position of the rotor poles relative to stator  22  that is depicted, has a value of 0, which increases upon clockwise rotation of the rotors. 
         [0058]      FIG. 5  shows values s 1  to s 6  for the various values of α. 
         [0059]    In the STATE  1  state, corresponding to startup, s 3  and s 5 =1, i.e. transistors  83  and  85  are conductive and the other transistors are blocked, so that a current flows from node  69  to node  67 . 
         [0060]    The circuit leaves state  1  and goes to STATE  2  when a transition state TRANS  1  is reached at which α&gt;=60° el. 
         [0061]    In the STATE  2  state, which therefore normally corresponds to an angle α between 60 and 120° el., s 1  and s 5 =1 and a corresponding current flow takes place. 
         [0062]    In the TRANS  2  state, when a has become greater than or equal to 120°, the transition to the STATE  3  state occurs. In this, s 1  and s 6 =1. 
         [0063]    When α&gt;=180° el. (TRANS  3 ), the transition occurs to STATE  4 , in which s 2  and s 6 =1. 
         [0064]    The subsequent transitions are as follows: 
         [0065]    TRANS  4  at α&gt;=240° el. 
         [0066]    TRANS  5  at α&gt;=300° el. 
         [0067]    TRANS  6  at α&lt;60° el. 
         [0068]    Signals s 1  to s 6  for the various rotation angle ranges are indicated in  FIG. 5 . A normal block commutation system is therefore preferably used, i.e. the currents are delivered in the form of current blocks whose amplitude can be modified by means of a PWM (Pulse Width Modulation) control system. 
         [0069]    Angle α can be measured in sensorless fashion (cf. the aforementioned European Patent 0 536 113 B1 and U.S. Patent RE-39076). 
         [0070]      FIGS. 6 and 7  show a first exemplifying embodiment for a practical implementation of an arrangement according to the present invention. Parts identical, or functioning identically, to ones in  FIGS. 1 to 5  are labeled with the same reference characters but with an apostrophe added, e.g.  52 ′ instead of  52 , and are usually not described again. 
         [0071]      FIG. 6  shows at the left a liquid cooler  90  whose inlet is labeled  92 ′. (The outflow is not depicted in  FIG. 6 .) This cooler  90  has at the center an opening  92  into which a bearing portion  94  of arrangement  20 ′ projects. Fan blades  42 ′ are implemented so that they either blow air through cooler  90 , i.e. from right to left, or draw air through the cooler from left to right. 
         [0072]    Bearing portion  94  serves to journal an external rotor  44 ′. The construction of the bearing system corresponds to that shown in  FIGS. 8 and 10  and is therefore described there. 
         [0073]    Journaled in bearing system  94  is a shaft  96  connected to which, via a hub  98 , is a rotor cup  100 . Where it projects into cooler  90 , said cup has a smaller diameter, which widens via a portion  102  into a rotor cup  104  of greater diameter in which is arranged a four-pole permanent magnet  106  for which rotor cup  104  serves as a magnetic yoke. This permanent magnet  106  has a copper layer  105  on its radially inner side in order to permit asynchronous startup. On its outer side, rotor cup  104  is injection-embedded in a plastic sheath  107  with which blades  42 ′ are integrally formed. Blades  42 ′ have on their outer side air-directing elements  108  that extend in an axial direction and reduce the air flow that flows, through gap  110  between a blade tip and fan housing  112 , from the delivery side of the fan to its intake side. This reduces fan noise. 
         [0074]    Located on the outer periphery of fan housing  112  is a closed cavity  114  in which a circuit board  116 , which serves to control the motor, is arranged. 
         [0075]    Located radially inside external rotor  106  is a coreless stator winding  118  that is preferably implemented as a three-phase winding to generate a rotating field, as described with reference to  FIG. 1 . This winding is supplied with a three-phase current from circuit board  116 . Circuit board  116  can be connected, for example, to a source for a three-phase current or to a DC power network. 
         [0076]    Stator winding  118  is located on the outer side of a partitioning can  120  that is equipped, for this purpose, with guidance projections  122 . These projections  122  serve to mount winding  118  in the desired angular position on partitioning can  120 . Partitioning can  120  is implemented as a magnetically transparent part, preferably made of plastic. 
         [0077]    Mounted inside partitioning can  120  in an axial projection  124  is a stationary shaft  126  whose right end in  FIG. 6  is guided in an axial projection  128  of a pump cover  130  that is equipped with an inlet connecting pipe  132 . During operation, cooling liquid flows through pipe  132  to a centrifugal pump  134 . 
         [0078]    Partitioning can  120  widens on its right side in  FIG. 6 , via a radially extending portion  135 , into a hollow-cylindrical portion  136  of greater diameter in which a pump wheel  138  rotates during operation. This portion  136  is connected to fan housing  112  via three struts or spokes  137 . These struts  137  extend transversely to an annular air passage  139 . 
         [0079]    This pump wheel  138  has an extension  140 , projecting in  FIG. 6  to the left, made of magnetizable material, e.g. made of plastic with embedded hard ferrite particles, and this extension  140  is here magnetized (like ring magnet  106 ) with four poles and is located radially inside coreless winding  118 , from which it is separated in liquid-tight fashion by partitioning can  120 . Extension  140  is equipped on its inner side with two sintered bearings  142 ,  144  by means of which it is rotatably journaled on shaft  126 . Axial extensions  124  and  128  form axial bearings for extension  140  and for pump wheel  138  integral therewith. 
         [0080]    An outlet pipe  146  proceeds approximately tangentially outward from hollow-cylindrical portion  136 . The flow through direction is indicated in  FIG. 7  by an arrow  148 ′. 
       Manner of Operation 
       [0081]    In operation, stator winding  118  is supplied with current from circuit board  116  in such a way that said winding generates a rotating electromagnetic field. As described in detail with reference to  FIG. 2 , this rotating field drives both external rotor magnet  106  and internal rotor magnet  140 . Any relative motion of rotor magnets  106 ,  140  is damped by copper layer  105 . 
         [0082]    Both external rotor magnet  106  having fan blades  42 ′, and internal rotor  140  having pump wheel  130 , are therefore synchronously driven in this fashion by winding  118 . A very compact design with reliable operation results, and arrangement  20 ′ can be combined directly with a liquid cooler  90 , as depicted in  FIG. 6 . 
         [0083]      FIG. 8  shows a second exemplifying embodiment of the invention. Identical or identically functioning parts are labeled with the same reference characters as in the previous Figures, and usually are not described again. 
         [0084]    As is apparent, the configuration of the two motors and the pump is unchanged as compared with the first exemplifying embodiment ( FIGS. 6 and 7 ). The configuration of external rotor  44 ″ is different, however, and fan housing  112 ′ is correspondingly longer than fan housing  112  in  FIGS. 6 and 7 . 
         [0085]    As in  FIGS. 6 and 7 , bearing portion  94  has a bearing tube  148  that is implemented integrally with partitioning can  120  and has a cylindrical internal opening  150  (cf.  FIG. 10 ). 
         [0086]      FIG. 10  shows, in its upper part, the corresponding bearing arrangement. The latter has two rolling bearings  154 ,  156  whose inner rings are axially displaceable on shaft  96 . Located between the outer rings of bearings  154 ,  156  is a spacing member  158  that is likewise axially displaceable on shaft  96  and has a somewhat smaller diameter than cylindrical internal opening  150 . 
         [0087]    Here as well, a hub  98 , on which a rotor cup  100 ′ is mounted, is mounted on the upper end (in  FIG. 10 ) of shaft  96 . Said cup has in this case a continuously cylindrical portion  104 ′ (of constant diameter) whose lower part in  FIG. 10  serves as a magnetic yoke for rotor magnet  106  of the external rotor. Fan blades  42 ″, which have the same shape as blades  42 ′ in  FIG. 6 , are mounted in the manner depicted on the outer side of the upper part of cylindrical portion  104 ′. 
         [0088]    Hub  98  has a depression  160  on its lower side (in  FIG. 10 ), and a compression spring  162  is arranged between said depression and the inner ring of upper rolling bearing  154 . 
         [0089]    Depression  160  is delimited toward the outside in  FIG. 10  by a downwardly projecting rim  164  that, when spring  162  is compressed, abuts against the outer ring of the upper rolling bearing  154 . 
         [0090]    A snap ring  166  is mounted at the lower end of shaft  96 , and the inner ring of lower rolling bearing  156  is pressed by spring  162  against this snap ring  166 . 
         [0091]    Upon assembly, bearing arrangement  94  is pressed into opening  150  of bearing tube  148  in the direction of an arrow  168 . Spring  162  is thereby compressed so that rim  164  pushes against the outer ring of upper rolling bearing  154 , and this outer ring pushes via spacing member  158  against the outer ring of lower rolling bearing  156 , so that the entire bearing arrangement  94  becomes pressed into bearing tube  148  until the outer ring of lower rolling bearing  156  abuts against a shoulder  170  ( FIG. 10 ) of internal opening  150 . 
         [0092]    Spring  162  then relaxes, and thereby displaces shaft  96  upward until snap ring  166  abuts against the inner ring of lower rolling bearing  156 , as shown by  FIGS. 6 ,  8 , and  10 . The assembly of bearing arrangement  94  is then complete, and it is not necessary to perform further work for this purpose in the interior of bearing tube  148 . 
         [0093]    As  FIG. 8  shows, bearing tube  148  has a cylindrical outer side  174 , and mounted thereon are two circuit boards  176 ,  178  that carry the electronic components for controlling the currents in coreless winding  118 . Hall sensors (not depicted), which serve to sense the position of internal pump rotor  140  and to control the commutation of coreless winding  118 , can be arranged on circuit board  176  that is located closer to winding  118 . Because these currents are consequently controlled by the position of internal rotor  140 , the latter also determines the rotation speed of external fan rotor  106 , although external rotor  106  can exhibit a certain slippage upon startup with respect to the rotating field generated by winding  118 . As already described, copper layer  105  is provided for this reason. 
         [0094]      FIG. 11  shows, at the bottom, pump cover  130  with its inlet connection pipe  132  and part  128  equipped with radial holes, in which part the lower end (in  FIG. 10 ) of shaft  126  is retained. 
         [0095]      FIG. 11  also shows centrifugal pump wheel  138  and internal rotor  140  with the two sintered bearings  142 ,  144  that rotate on stationary shaft  126 , as described with reference to  FIG. 6 . 
         [0096]    Many variants and modifications are of course possible within the scope of the present invention.