Abstract:
An electronically commutated motor has a rotor ( 34 ) that is rotatable about an axis (D), and it has a stator arrangement ( 30 ) in which is provided a number, evenly divisible by three, of salient stator poles that are wound with winding strands, associated with which, for the connection thereof, are busbars ( 44, 46, 48 ) arranged on edge. The latter are arranged in an insulating part ( 42 ). Each of these busbars ( 44, 46, 48 ) has a central portion ( 78 ), a first end portion ( 90 ) and a second end portion ( 56 ). These busbars ( 44, 46, 48 ) are insulated from one another and are nested into one another in a manner that minimizes relative displacement thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S)  
       [0001]    This application claims priority from German application 10 2008 009 845.0, filed 12 Feb. 2008, the disclosure of which is hereby incorporated by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to an electronically commutated motor, and more particularly to one capable of fast start-up. 
       BACKGROUND 
       [0003]    Electronically commutated motors that start within a very short time, and are consequently designed so that they enable high torque and have low internal resistance, are necessary in many applications. 
       SUMMARY OF THE INVENTION 
       [0004]    It is therefore an object of the invention to make available a novel electronically commutated motor. 
         [0005]    According to the invention, this object is achieved by a motor structure in which a rotor is rotatable about a central axis, a stator arrangement has a plurality of salient poles, whose number is divisible by 3, each pole has a coil thereon, and a plurality of busbars, arranged on edge in an insulating element, are provided for electrical connection of the stator coils. The busbars are nested together in such a way that relative circumferential movement thereof is mechanically limited or restrained. Such a motor has both a compact configuration and high torque, and is easy and economical to manufacture, especially in an automated manner. 
     
    
     
       BRIEF FIGURE DESCRIPTION 
         [0006]    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. 
           [0007]      FIG. 1  depicts a wound stator lamination stack that is equipped on one end face with special busbars; 
           [0008]      FIG. 2  is a plan view from above of the arrangement according to  FIG. 1 ; 
           [0009]      FIG. 3  is a winding diagram for the stator winding depicted in  FIG. 1 ; 
           [0010]      FIG. 4  shows, as an example, how the winding strands of  FIG. 3  are interconnected into a multiple parallel delta winding; 
           [0011]      FIG. 5  is a perspective depiction of one of the busbars used in the stator lamination stack of  FIG. 1 ; 
           [0012]      FIG. 6  is a depiction corresponding to the upper part of  FIG. 1 , but as an exploded view; 
           [0013]      FIG. 7  is a plan view from above of the upper part of  FIG. 1 , but in the unwound state; 
           [0014]      FIG. 8  is a section looking along line VIII-VIII of  FIG. 7 ; 
           [0015]      FIG. 9  is a three-dimensional depiction of details of an end ring; 
           [0016]      FIG. 10  is a three-dimensional depiction of the electrical connection of a power plug to the end ring; 
           [0017]      FIG. 11  depicts, in section, a motor having a side-mounted power plug; 
           [0018]      FIG. 12  is an enlarged sectioned depiction of a hook having a winding wire hooked into it; and 
           [0019]      FIG. 13  shows the operation of resistance welding by means of welding tongs. 
       
    
    
     DETAILED DESCRIPTION  
       [0020]      FIG. 1  shows stator  30  of a three-phase motor  32  ( FIG. 4 ), said motor having here, as an example, a permanent-magnet internal rotor  34  that is indicated only very schematically in  FIG. 4  and of course can have a variety of configurations and numbers of poles depending on the design of motor  32 , as is known to one skilled in the art of electrical machinery. An eight-pole rotor is depicted. Lamination stack  36  has twelve slots  1  to  12  that are insulated in the usual way, e.g. by means of a plastic coating (not depicted). These slots define twelve salient poles. Each pole is wound with a coil, and these coils are labeled  1 ′ to  12 ′. 
         [0021]    Stator  30  has, in the usual way, a lamination stack  36  on whose lower end (in  FIG. 1 ) is mounted an insulating ring  38  that forms part of the winding body for the stator winding. This ring  38  is occasionally also referred to as an “end plate,” and, in this embodiment, does not carry any electrical connecting elements but serves only as part of the coil former and as insulator for the winding, but can have the same shape as depicted at the bottom of  FIG. 6 , although without the three busbars that are depicted in the upper Dart of  FIG. 6  and are not needed on lower ring  38 . 
         [0022]    As shown in  FIG. 1 ,  FIG. 6 , and  FIG. 7 , there is arranged, at the upper end of stator lamination stack  36 , an insulating ring  42  that can also be referred to as an annular disk and that likewise has the function of serving as part of the coil former for the winding, and as an insulator for it. In this embodiment, this upper ring  42  carries three busbars  44 ,  46 ,  48  standing on edge, which can be identical but which are offset by an angle of 120° mech. in the manner evident from  FIGS. 2 ,  6 , and  7 . 
         [0023]      FIG. 5  shows busbar  44 , which is usually (for practical reasons) implemented identically to busbars  46  and  48 ; for that reason, the individual busbars contain redundant parts that of course could also be omitted, although in most cases this would increase the cost. Busbars  44 ,  46 ,  48  are parts that appear to be simple, but that in terms of their function are based on a long and difficult development process and on numerous inventive steps, since they must satisfy, in an optimal manner, widely varying functional requirements. 
         [0024]    In the exemplifying embodiment, each busbar  44 ,  46 ,  48  is approximately in the shape of a ring segment and, in this example, extends over approximately 280 to approximately 300° mech., preferably approximately 295° mech.; in other words, each ring has a missing portion  50  that allows the three rings  44 ,  46 ,  48  to be ingeniously nested within one another and fastened to prevent rotation relative to one another, and enables the winding wire to be temporarily secured in a simple manner at its ends, and prevents incorrect assembly. 
         [0025]    As  FIG. 5  shows, busbar  44  has on its lower (in  FIG. 5 ) portion  56  an elongated opening  58  that serves for connection to a plug  60 , which is depicted in  FIG. 11  and serves to supply motor  32  with electrical energy. 
         [0026]    Located approximately opposite this opening  58  is a notch  60  that, as shown in  FIG. 8 , serves for engagement with a projection  110  of ring  42 , thereby preventing the latter from rotating at that location relative to the relevant busbar; in other words, slot  60 U of busbar  46  (U) and projection  114  serve to largely immobilize busbar  46  (U) in the vicinity of the associated projection  110 , which is advantageous for automated production. 
         [0027]    Opening  58  is followed, in the clockwise direction, by a hook  62  that is stamped out of busbar  44  and is bent inward in the manner depicted. During winding, a winding wire  63  is first hooked onto this hook  62  (see  FIG. 12 ) and is then welded to hook  62  by resistance welding; this can be done using an automatic apparatus. 
         [0028]      FIG. 13  shows a resistance welding operation in which lead  63  is welded to hook  62  by means of welding tongs that are closed in the direction of two arrows  69 ,  71 . For that purpose, the two jaws  65 ,  67  of the welding tongs are guided over hook  62  from above, and then brought against it in the direction of arrow  69 ,  71 . Hook  62  is bent together over lead  63  with the aid of jaws  65 ,  67 , and at the same time is heated by a current flowing through jaws  65 ,  67 . Wire  63  is heated by this current, burning off its insulation. Lead  63  thereby becomes welded to hook  62 , and a mechanically stable and electrically highly conductive connection is created.  FIGS. 12 and 13  are schematic depictions that indicate ring  42  and the other parts only very roughly, in order to present the working principle of the welding operation in a simple and understandable manner. 
         [0029]    Hook  62  is followed by a portion  64 , having a length of approximately 60° mech., in which busbar  44  has a rectangular cross section with no particular features. It is followed by a portion  66  having a hock  68 , and adjacent thereto an elongated opening  70 , a notch  72  being provided in portion  66 . 
         [0030]    Portion  66  is followed by a bending point  74  at which radius r 1  of portion  64  decreases to a somewhat smaller radius r 2  of a portion  78  that, like portion  64 , has an angular extension of approximately 60° mech. Portion  78  extends as far as a bending point  80  where radius r 2  of portion  78  decreases to a somewhat smaller radius r 3 . 
         [0031]    Bending points  74 ,  80  are guided into corresponding complementary cavities B of ring  33 , which are depicted in the lower part of  FIG. 6 . They prevent rings  44 ,  46 ,  48  from being inserted into ring  42  in any positions other than the predetermined ones. 
         [0032]    Bending point  80  is followed in the clockwise direction in  FIG. 5  by a hook  82 , and then, with a spacing of approximately 40° mech. from hook  82 , by a portion  84  that protrudes upward from busbar  44  and has an elongated opening  86  that, here as well, is located opposite a notch  88 . 
         [0033]    Portion  84  is once again followed in a clockwise direction, and with an angular spacing of approximately 45° mech., by an upwardly protruding portion  90  on which two hooks  92 ,  94  are provided. There the relevant busbar  44 ,  46 ,  48  ends. 
         [0034]    Hooks  62 ,  68 ,  82 ,  92 , and  94  protrude into the interior of the relevant busbar  44 ,  46 , or  48 . During automated winding, winding wire  63  is hooked onto these hooks and then welded to the relevant busbar, the insulation of wire  63  being burned off by the heat produced during welding, so that a good electrical connection is produced. 
         [0035]    Because busbars  44  (W),  46  (U), and  48  (V) shown in  FIG. 6  can be identical, their elements are labeled with the same reference characters as in  FIG. 5  but indexed with U, V, or W (for example,  68 J,  68 V, or  68 W) so that the depiction does not become too complicated. 
         [0036]    In the present embodiment, the entire winding for all phases is wound from a single, uninterrupted wire segment  63  whose one end  63 A is electrically and mechanically connected to hook  92 W of part  90 W, and then passes through all twelve coils  8 ′,  9 ′,  10 ′,  11 ′,  12 ′,  1 ′,  2 ′,  3 ′,  4 ′,  5 ′,  6 ′, and  7 ′ to its other end  63 B. End  63 B is electrically and mechanically connected to hook  94 W of part  90 W, so that winding wire  63  is preferably continuous. 
         [0037]    From hook  92 W wire  63  goes to coil  8 ′, and from there on to hook  62 V. From there it continues to coil  9 ′ and from there on to hook  68 U, and from there to coil  10 ′. From there wire  63  goes to hook  82 W, and from there to coil  11 ′, and from that to hook  94 V. Hook  92 V of busbar  48  is not used and is consequently redundant. 
         [0038]    From hook  94 V wire  63  continues to coil  12 ′, and from that to hook  62 U, and on to coil  1 ′. From that, wire  63  continues to hook  68 W, and from there via coil  2 ′ to hook  82 V and on, via coil  3 ′, to hook  94 U. Hook  92 U is not used on this busbar. 
         [0039]    From hook  94 U, the winding proceeds via coil  4 ′ to hook  62 W, and from there via coil  5 ′ to hook  68 V, and from there continues via coil  6 ′ to hook  82 W, and then via coil  71  to wire end  63 B ( FIG. 3 ) and to hook  94 W. 
         [0040]    In this manner, the entire winding can be wound automatically and also connected automatically to the associated hooks. 
         [0041]    The result is the circuit according to  FIG. 4 , i.e. the example refers to a quadruply parallel delta winding that is especially suitable for low-voltage drive systems. Between terminals V and W, for example, the four coils  2 ′,  5 ′,  8 ′, and  11 ′ are connected in parallel, and the result is analogous for the other phase terminals as indicated in  FIG. 4 . 
         [0042]    Because the currents in stator winding arrangement  30  can be substantial, it is important to make low-impedance connections available throughout the motor (or generator). 
         [0043]      FIG. 9  is a perspective depiction of part of upper insulating ring  42 . The latter has a cavity  100  for the reception of busbar  46  (U), a cavity  102  for the reception of busbar  48  (V), and a cavity  104  for the reception of busbar  44  (W). The busbars are pressed into these cavities and retained therein. Because of the heating that occurs during welding, part  42  is preferably crosslinked by radiation so that it can withstand these elevated temperatures. 
         [0044]    In a predetermined angular region  108  that is depicted in  FIGS. 1 ,  2 , and  9 , insulating ring  42  has a marking  110  (here, for example, in the form of an elongated slot), and in this region  108  the three busbars  44 ,  46 ,  48  are secured in the circumferential direction by special projections. 
         [0045]    A projection  112  ( FIG. 8 ) at the bottom of cavity  102  secures busbar  48  (V) in the circumferential direction in cavity  102 , by engaging positively into slot  88 V of busbar  48 . As a result, busbar  48  is precisely immobilized in the circumferential direction in angular region  108 , which proves extremely advantageous for further automatic processing. 
         [0046]    A projection  114  ( FIG. 8 ) at the bottom of cavity  104  secures busbar  44  (W) in the circumferential direction in cavity  104  by engaging into slot  72 W of busbar  44  (W). 
         [0047]    A projection  110  ( FIG. 8 ) at the bottom of cavity  100  secures busbar  46  (U) in cavity  100  by engaging positively into slot  60 U ( FIG. 8 ) of busbar  46  (U). 
         [0048]    As a result, the elongated openings  70 W,  86 V, and  58 U of  FIG. 9  have a precisely defined position relative to one another and relative to elongated slot  110  ( FIG. 9 ), so that three flat conductors  120 ,  122 ,  124  of a lateral power plug  60  can be inserted into these elongated openings according to  FIG. 10 , as shown in  FIG. 10 ; and these flat conductors  120 ,  122 ,  124  can then he electrically and mechanically connected to busbars  44 ,  46 ,  48 , for example by laser welding, as depicted in  FIG. 11 . 
         [0049]    Flat conductors  120 ,  122 ,  124  are retained in power plug  60  by injection molding (see  FIG. 11 ), and they enable a low-impedance connection from plug  60  to stator  30 ; this connection can be produced in a largely or completely automated manner. 
         [0050]    Power plug  60  is inserted, with a cylindrical part  130 , into a cylindrical opening  132  of a motor housing  124 . This housing  134  is depicted only partially in  FIG. 11 . An O-ring  136  is inserted into an annular groove  138  of cylindrical part  130  and serves for sealing between the latter and motor housing  134 . Motor plug  60  is mounted on motor housing  134  by two screws, of which screw  142  is visible in  FIG. 11 . 
         [0051]    During manufacture, firstly the three busbars  44 ,  46 ,  48  are pressed into the cavities  100 ,  102 ,  104  in order to retain them there securely and achieve highly precise positioning of these busbars in angular region  108 . Stator  30  is then wound, usually with an automatic winder, and winding wire  63  is welded to the various hooks into which it is hooked, as depicted by way of example in  FIGS. 12 and 13 . 
         [0052]    Power plug  60  is then installed by inserting flat conductors  120 ,  122 ,  124  laterally into elongated openings  70 U,  86 V, and  58 W and welding them there. The bearing bells (not depicted) are installed, together with the shaft and rotor  34 . Because these parts are not directly related to the present invention, they are depicted only schematically. 
         [0053]    Numerous variants and modifications are of course possible within the scope of the present invention.