Abstract:
In a converter motor, the converter electronics are integrated into the motor connecting box. The lower part of the motor connecting box is formed in one piece with a housing of the converter motor and at the front end than at the rear end. The edge of the upper part of the motor connecting box is shaped appropriately slantwise, so that the upper side is aligned to be straight. Connecting cables for power current and data communications issue from a stepped gradation in the upper part. The upper part has a plurality of openings for passing through cables which are oriented at an angle of less than 90° to one another and to the motor axis.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a motor connecting box and a converter motor. 
     SUMMARY 
     A converter motor includes, e.g., an electrically operated drive unit which includes at least one motor unit and an electronic subassembly, the converter unit, for controlling the motor unit, particularly for regulating the rotational speed and/or the torque. The motor unit may include, in this connection, a permanent-magnet rotor, a squirrel-cage rotor or a combination of the two, or may be arranged as an external-rotor motor. 
     Example embodiments of the present invention to refine a converter motor, improving the heat dissipation being intended. 
     Important features of a motor connecting box are that a lower part and an upper part are provided, a step being formed in the upper part which includes two plateau surfaces and an end face connecting the plateau surfaces, and in whose end face, openings are arranged for cable bushings. Consequently, a possibility is created of guiding the connecting cables of a converter motor into the motor connecting box, in which the cable bushing is protected on the housing in a plurality of directions by projecting housing parts. The arrangement of a step offers the additional advantage that connecting devices, such as cable glands, connection sockets or connection plugs do not project, or do not project extensively beyond the structural dimensions of the connecting box. Consequently, for one thing, a more compact overall structural dimension is achieved, and for another thing, a more certain protection of sensitive parts from impact damage is achieved. 
     In example embodiments, the step has a plane of symmetry, openings for cable bushings being provided on both sides of the plane of symmetry. The plane of symmetry preferably reflects the position of the motor axis when the motor connecting box is in the mounted state. The advantage in this context is that a flexible cable routing is practicable, depending on requirements, openings on both sides of the plane of symmetry being used for cable bushings, or being closed unused. 
     In example embodiments, the openings for cable bushings point away from the plane of symmetry. Consequently, it is advantageously achieved that the angular ranges which are covered by each opening in each case, limited by the bending radius of the connecting cables, overlap and complement one another. Thus, in particular a cable routing laterally away from the plane of symmetry is possible, that is, away from the motor axis. The motor connecting box does not have to be re-positioned for this. 
     In example embodiments, a first opening for cable bushings is provided in a first planar area of the end face of the step, the mathematical extension of the first planar area intersecting at least two lateral surfaces of the lower part. This states a simply producible arrangement of the openings, which makes possible a cable routing to two sides of the motor connecting box, by having the mounting surface cutting off a corner of the motor connecting box in a slantwise manner. 
     In example embodiments, a second opening for cable bushings is provided in a second planar area of the end face of the step, the mathematical extension of the first planar area intersecting at least two lateral areas of the lower part and the mathematical extension of the first planar area. Consequently, the opposite side of the motor connecting box is advantageously usable for laying the cable. 
     In example embodiments, an upper edge is provided on the lower part, which runs diagonally from a higher end to a lower end, the slanting of the upper edge of the lower part and the step in the upper part having a diminishing height in the same direction. The difference in height, which comes about due to the arrangement of the step, is thus at least partially usable for the one-sided superelevation of the connecting box base. Consequently, components such as coils or capacitors, which require a minimum insertion height, are protected by the connecting box base even when the cover has been removed, while no unnecessary installation space is given away in regions having small part electronic components. In addition, the height of lift of the cover is shortened when it is lifted off. 
     In still another advantageous embodiment example embodiments, a third opening for cable bushings in a third planar area is provided in the end face of the step, the third opening having a lesser diameter than the second opening and the first opening. This provides the possibility of an additional cable bushing for communication cable. Since these cables are considerably thinner in application cases than the power cables, a smaller bending radius is optional during the laying of the cable. The third planar area is preferably situated between the first planar area and the second planar area. It is therefore not necessary to provide openings in a plurality of directions. This saves production steps and improves the sealing. 
     In example embodiments, the first planar area and the second planar area include an angle whose apex points in the direction of the diminishing height of the step. It is of advantage, in this context, that a region facing away from the drive side of the motor is accessible to the cable routing. 
     In example embodiments, the included angle has an angular aperture between 60° and 100°. The angular aperture of the included angle preferably amounts to 80°. Consequently, advantageous geometric relationships are set, using which the covering of an angular range of more than 270° is usable for cable routing. 
     In example embodiments, converter electronics are provided on the inside of the box. Because of the arrangement of openings of the cable bushings situated slantwise to one another, the motor connecting box does not have to be re-positioned for a changed cable routing. Therefore, the motor connecting box is not limited to a square or, more generally, n-cornered base shape, that is, a base shape having a more than binary rotational symmetry, but may extend rectangularly, for example, over the entire length of a motor housing. There is thus sufficient space for providing converter electronics, and the motor connecting box is equipped for the integration of a compact converter motor. 
     In example embodiments, the converter electronics includes a power component, and, at the bottom of the lower part, a planar contact area is provided, the power component being laid upon the contact area for the heat dissipation. One advantage, in this context, is that the housing of the motor connecting box is usable for the heat dissipation of the power components, especially the IGBT&#39;s, which, as converter output stage, take over control of a motor. Thus, a large cooling surface is made available, which is able to be connected to additional cooling surfaces. 
     In example embodiments, the power component is situated on a printed circuit board, the printed circuit board pressing the power component onto the contact area. This has the advantage that, for mounting the converter, in a first step the printed circuit board is soldered, and in a second step, the printed circuit board is inserted into the housing. The fastening of the power component takes place directly with the insertion. Additional mounting steps, such as the mounting of a holding-down clamp, may be omitted. 
     In example embodiments, a fastening frame is provided, to which the printed circuit board is fastened, and which covers the printed circuit board from above, openings being provided, in the fastening frame, through which plug contact parts of the printed circuit board extend. The advantage is that devices are provided as a mounting aid, to protect the printed circuit board from damage. The fastening frame is also filled up with a heat-conducting molding compound, which gives rise to a heat dissipation of the entire electronics system to the bottom of the motor connecting box. 
     In example embodiments, the fastening frame is screwed together with the lower part, the fastening frame pressing the printed circuit board against the bottom of the lower part, when it is in the snapped-in or screwed-in state. An elastomeric cushion is preferably situated between the power components and the printed circuit board. Consequently, the contact force of the fastening screws for the fastening frame are used for pressing the power components against the contact area. 
     In example embodiments, the fastening frame has a rim, an additional printed circuit board being clipped onto the rim. Springy tabs having lugs are preferably provided on the rim, onto which the additional printed circuit board is clipped. This makes available a compact electronics component, the first printed circuit board and the additional printed circuit board being mounted before the insertion of the fastening frame into the lower part. The dual design of the electronics system also makes possible the modular exchange of the upper part, that is, the additional printed circuit board, having a rectifier and intermediate circuit, for an alternative embodiment without rectifier, for example. For, a rectifier may be omitted in the case of a contactless power supply according to German Published Patent Application No. 10 2005 022 367. All the features described there of a contactless power supply are taken up as a component of this description. 
     In example embodiments, the additional printed circuit board is connected to the plug connector of the first printed circuit board via a fitting plug connector. Consequently, the electronic component made up of fastening frame, first printed circuit board and additional printed circuit board is able to be mounted by being clipped on. The plug connectors are preferably positioned on the printed circuit boards in such a way that they are connected when the clipping on takes place. Soldering them together is thus no longer required. During maintenance, individual components are easily exchanged. 
     In example embodiments, an intermediate circuit capacitor and/or a rectifier module is situated on the additional printed circuit board, in a region that is surrounded at least partially by the higher end of the lower part. The step in the upper part, on the inside of the motor connecting box, preferably forms and surrounds a region in which an intermediate circuit capacitor and/or a rectifier module of the converter electronics is or are situated. Thus, the enclosed installation space formed by the step is utilized for those components that require much space, especially in height. The base of the motor connecting box surrounds these components and protects them even when the cover is removed. 
     The rectifier module and/or the intermediate circuit capacitor are provided as options in example embodiments. The rectifier module and the intermediate circuit module are preferably included in one supply module, for instance, mounted on a common printed circuit board that is separate from the power output stage. In example embodiments, the power output stage of the converter electronics is connected directly to the output of a rectifier module of the matching controller of a system for contactless energy supply, as described in German Published Patent Application No. 103 39 340, for example. Thus a model series of converter motors having different functualities is formed. 
     In example embodiments, an outer tube-shaped part is provided on the lower part, for accommodating a motor unit, the bottom of the lower part forming a part of the first tubular part. Consequently, the power semiconductors are connected to a housing part acting as a large cooling body. 
     In example embodiments, an inner tube-shaped part is provided in the outer tube-shaped part for the accommodation of the stator of a motor unit, the axis of the outer tube-shaped part extending parallel to the axis of the inner tube-shaped part. Tube-shaped designates in general a part that is arranged substantially discretely or continuously rotationally symmetrical about an axis, is hollow on the inside and is provided overall with a wall thickness that is thin as compared to its diameter. 
     In example embodiments, the slanting of the upper edge of the lower part has a diminishing height in the direction of the axis of the first tube-shaped part. This has the advantage that the openings for the cable bushings are able to be positioned in such a way that an angular range is covered which includes both sides of the motor and the back side, that is, the side facing away from the drive side. The drive side of the motor connecting box, that is in any case not usable for cable bushings, is thus usable for the accommodation of the large part components, such as capacitors and/or coils and/or transformers of the converter. 
     In example embodiments, the lower part and the outer tube-shaped part are produced from one cast body. The arrangement from one cast body becomes possible since the motor connecting box does not have to be re-positioned in spite of a flexible cable routing possibility. An advantageous heat dissipation is thus achieved, since plug connectors, or other connections that could act as a heat barrier, are completely omitted. 
     In example embodiments, the outer tube-shaped part and the inner tube-shaped part are produced from one cast body, the two parts being connected via radially extending crosspieces. A complex motor housing is thus provided which has space for a converter, which is jointly cooled by the self-ventilator of a motor. The arrangement of the two housing parts that are interspersed with each other offers the advantage of large cooling areas for the motor and the converter, which, in addition, are thermally decoupled from each other. 
     Among features of a converter motor are that an inner tubular part is provided, which surrounds the stator, and an outer tubular part is provided which surrounds the inner tubular part, and at whose outer side the motor connecting box is provided, a ventilator being provided in the outer tubular part which moves air along the inside of the outer tubular part. The cooling air between the motor unit and the converting unit advantageously causes a thermal decoupling of the two units. Thus the heat dissipation is improved. The step in the upper side of the motor connecting box advantageously makes a flexible cable routing possible, without one&#39;s having to rotate or displace the motor connecting box. The motor connecting box and the motor housing may accordingly be produced from one cast body. Unfavorable heat transitions because of connecting points drop out. In addition, production is simplified. 
     In example embodiments, the slanting of the upper edge of the lower part has a diminishing height in the direction of the axis of the outer tubular part, the region of great height being situated on the drive side of the converter motor. The motor connecting box preferably extends over the entire axial length of the motor housing. Consequently, the converter electronics are able to be integrated into the motor housing at as small as possible an installation measurement. 
     In example embodiments, the motor shaft is situated in the plane of symmetry of the motor connecting box. Thus, the converter motor is able to be connected symmetrically. 
     Further features and aspects of example embodiments of the present invention are described below. 
     LIST OF REFERENCE NUMERALS 
     
         
           1  converter motor 
           2  outer housing 
           3  stator housing 
           4  end shield A 
           5  drive flange 
           6  ventilator cover 
           7  connecting box 
           8  connecting box base 
           9  connecting box cover 
           10  bolt 
           11  recessed grip 
           12  cable gland 
           13  cable gland 
           14  crosspiece 
           15  motor shaft 
           16  cable passage opening 
           17  upper side of cover 
           18  shoulder 
           19  screw plug 
           20  end face 
           21  end face 
           22  planar area 
           23  screw plug 
           24  cover edge 
           25  centrifugal brake lever 
           26  self-ventilator 
           27  opening 
           28  base edge 
           29  front base part 
           30  rear base part 
           31  connecting box bottom 
           32  power component 
           33  contact area 
           34  air channel 
           35  printed circuit board 
           36  fastening frame 
           37  tab 
           38  plug connection 
           39  plug connection 
           40  lug 
           41  reinforcement rib 
           42  lug 
           43  planar area 
           44  lateral surface 
           45  lateral surface 
           46  lateral surface 
           47  step 
           48  rim 
           49  intermediate circuit capacitor 
           50  plug connector 
           51  connecting channel 
           60  connecting box 
           61  plateau surface 
           62  plateau surface 
           63  plane of symmetry 
           64  opening 
           65  opening 
           66  opening 
           67  opening 
           68  end face 
           69  lateral surface 
           70  lateral surface 
           80  printed circuit board 
           81  printed circuit board 
           82  USB (universal serial bus) connection 
           83  plug connector 
           84  rectifier stage 
           85  intermediate capacitor 
           90  opening 
           91  cable gland 
           92  cable gland 
           93  cap 
           94  cap 
           95  cable gland 
           96  cap 
       
    
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a converter motor having a motor connecting box. 
         FIG. 2  is a view of the converter motor illustrated in  FIG. 1  from above. 
         FIG. 3  is a view of the converter motor illustrated in  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the motor connecting box illustrated in  FIG. 1 . 
         FIG. 5  illustrates a motor connecting box. 
         FIG. 6  is a cross-sectional view of a converter motor having an optional rectifier unit and an optional intermediate circuit unit. 
         FIG. 7  an oblique view onto a motor connecting box. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a converter motor  1  in a side view. A tubular outer housing  2  coaxially surrounds a tubular inner housing  3 . Inner housing  3  includes the motor unit of converter motor  1 . The stator of the motor unit is situated in inner housing  3 , and is held by the latter in a force-locking manner. Inner housing  3  is closed off on the drive side of the motor unit by an end shield A  4 , which goes over into a drive flange  5 . The drive side of motor shaft  15  extends all the way through drive flange  5  for connection to an input shaft of a gearing. At the opposite end of converter motor  1 , outer housing  2  is closed off by a ventilator cover  6  in a grid-like manner. 
     Inner housing  3  is rigidly connected to outer housing  2  via crosspieces  14 . Inner housing  3  and outer housing  2  are made of a common casting. Aluminum is preferably selected as the material. 
     On the upper side of outer housing  2  there is a connecting box  7 . Connecting box  7  includes an upper part arranged as connecting box cover  9 , which is mounted upon a lower part, the lower part being formed of a connecting box base  8  and a region of outer housing  2 . Connecting box base  8  is arranged as one piece with outer housing  2 , and it surrounds a region of outer housing  2  which forms the bottom of connecting box  7 . 
     Connecting box cover  9  is fastened on the connecting box base by screws  10 . 
     Connecting box base  8  has an obliquely extending upper edge, whose height above outer housing  2  is higher on the drive side than at the opposite end of converter motor  1 . A slanting having a downward height curve is thus provided which diminishes along the motor axis, away from the drive side. Connecting box cover  9  has a corresponding slant. In particular, the angles of the slanting with respect to the side walls are the same for the lower part and the upper part, so that the side walls go over into one another in a substantially even manner. 
     In the upper region of connecting box cover  9 , a step is provided, which is formed by upper side of cover  17  and a shoulder  18 , as well as a side area connecting the two areas. 
     Upper side of cover  17  and shoulder  18  thus each define a plateau of different heights, shoulder  18  being terraced compared the upper side of the cover. Because of the step, a vertical run is formed, which extends in the same direction as the slanting at connecting box base  8 , in a falling-off manner. The step includes a lateral surface  46 , on which cable glands  12 ,  13  are situated for sealing cable bushings. 
     At opposite sides of connecting box cover  9 , in each case an axially extending recessed grip  11  is provided, using which connecting box cover  9  may lifted off. On the front side of connecting box cover  9  there is also provided a planar beveling  21  which goes over into upper side of cover  17 . 
       FIG. 2  shows converter motor  1  from above. Inner housing  3  is connected to outer housing  2  via a cable passage opening  16 . Cable passage opening  16  is used for leading through the connecting cable from the connecting box to the motor unit. 
     Upper side of cover  17  is bordered by beveling  21 , two lateral surfaces  45  and the end face of the step that is formed by planar areas  22 ,  43  and end face  20 . In planar areas  22 ,  43  two openings respectively are applied for cable bushings, which are able to be closed by screw plugs  19  or by cable glands  12 . 
     First planar area  22  is situated slantwise to the sides of connecting box base  8 . The mathematical plane ideally defined by planar area  22  intersects two lateral surfaces  44 ,  45  of connecting box base  8 . As a sectional plane, the mathematical plane would cut off a corner of the base area of the lower part. Because of the slantwise extending arrangement of the openings for the cable bushings, a cable is able to be brought out into various directions from the connecting box, without re-positioning the connecting box. Because of the step, the area around the openings is protected by projecting housing along the motor axis and transversely to the motor axis, whereby the strain on the cable routing is relieved. 
     The lateral surface of the step includes a second planar area  43 , in which two additional openings have been applied for the cable bushing. These opening are closed by cable glands  12  that are screwed in. Cable glands  12  also fit the openings in first planar area  22 . The mathematical plane ideally defined by second planar area  43  intersects two lateral surfaces  44 ,  45  of connecting box base  8 . As a sectional plane, the mathematical plane would cut off a corner of the base area of the lower part. Second planar area  43 , together with first planar area  22 , includes an angle whose angular aperture amounts to 80°. Consequently, the second planar area covers a semicircle of possible cable routings originating from the openings, which has only a section in common with the corresponding semicircle of the first planar area. The possible cable routings thus cover a segment having an angular aperture far greater than 180°, without the connecting cable having to be bent or buckled too much. 
     Between first planar area  22  and second planar area  43  a third planar area is situated, in the form of an end face  20 , in which an opening is provided whose diameter is less than that of the openings in first planar area  22 . The opening is accordingly closed, using a cable gland  13  which is smaller than cable gland  12 . Cable gland  13  is dimensioned exactly so that it is able to accommodate a cable for data communication. Cable glands  12  are dimensioned in such a way that in each case they are able to accommodate a cable for power current for supplying a motor in the kW range. Since a cable for data communications is substantially thinner than a power current cable, it is easier to bend it. Thus, appropriate openings in different directions do not necessarily have to be provided. 
       FIG. 3  shows a converter motor  1  from behind, that is, from the side that is opposite to the drive side. Under ventilator cover  6 , a ventilator  26  is situated. Ventilator  26  is arranged either as a self-ventilator or as an extraneous ventilator. It sucks in air through open-worked ventilator cover  6  and blows it through the intermediate space that is formed by outer housing  2  and inner housing  3 . The air thus sweeps over the surface of the inside of the tubular outer housing and eventually exits at an annular opening on the drive side. 
     An additional bore is applied into end face  20 , which is closed by screw plug  23 . A cable gland  13  is alternatively able to be screwed into the opening. 
     Cover edge  24  of the upper part of connecting box  7  has a surface which is substantially aligned with the surface of the side walls of cable gland  8 . In this instance, the surfaces of the side walls of connecting box cover  9 , particularly of cover edge  24 , may protrude slightly, in order to conceal the sealing ring put in between upper part and lower part from liquid running down, and thus to effect greater tightness. 
       FIG. 4  shows a section through connecting box  7 . Front base part  29  of connecting box base  8  has a greater height as compared to outer housing  2  than compared to rear base part  30 . Base edge  28  of connecting box base  8  thus has a slanting having a height dropping off from the drive side of the motor to the ventilator side. Thus, at connecting box cover  9  a step  47  is able to be formed in a space-saving manner, by providing the lower edge of connecting box cover  9  with an appropriate slant. Step  47  includes two plateau areas which each have a substantially constant height above outer housing  2 , and an end face which connects the plateau areas and extends substantially perpendicular to motor axis  15 . Because of step  47 , a cable that is brought out of a cable gland  12 ,  13  situated at the end face is protected at the exit location by parts of connecting box cover  9 . Because of the slanting, the wall, formed to be higher in front base part  29 , forms a protection from larger electronics, such as terminal boards or plug connectors to the power current connection in the front part (left part in  FIG. 4 ) of the connecting box inner chamber, while in the back part (right part in  FIG. 4 ) space is created for openings  27  for the cable bushing, at an altogether minimum overall installation space of connecting box  7 . In the rear part of connecting box inner space, there is additional space for low height installed electronics, for instance, signal electronics for data communications. 
     In the connecting box inner space there is situated a printed circuit board  35  having the electronics of the converter. On the lower side of printed circuit board  35 , power components  32  are mounted in a row transverse to the motor axis. Power components  32  have a contact area for heat dissipation. These contact areas are placed onto a contact area  33 , which are worked into connecting box bottom  31  in a particularly planar manner. Between contact area  33  and power component  32 , heat-conducting paste is applied to connecting box bottom  31 , for the further improvement of the thermal connection. 
     The lower part of connecting box  7  is produced from one casting with outer housing  2 , and connecting box bottom  31  is a region of outer housing  2  which is cooled on its inside by an air flow driven by self-ventilator  26  in air channel  34 . Consequently, the entire surface of the outer housing, which extends in a tubular manner about motor shaft  15 , that carries ventilator  26 , is usable for heat dissipation. Power components  32  are therefore thermally well coupled to a large surface which, in addition, is swept over by cooling air. One may therefore do without cooling ribs. 
     Printed circuit board  35  is fastened by lugs  40  to a fastening frame  36 . Fastening frame  36  completely covers printed circuit board  35 , except for individual apertures for plug connector  38 . Fastening frame  36  is screwed together with the bottom of the lower part. Consequently, the electronics are protected from above, that is, from a direction towards the opening of connecting box base  8 , against inadvertent touching or damage. After installation in fastening frame  36 , printed circuit board  35  is molded with a heat conducting molding compound. This molding compound produces a thermal coupling of additional electronic components of printed circuit board  35  to additional planar contact surfaces in the bottom of the connecting box. Between the molding compound and the bottom, a protective foil is inserted, which is interrupted at the contact surfaces. 
     Printed circuit board  35  has a plug connector  50  pointing downwards, to which the windings of the motor unit are connected. For this, the connecting lines are guided through a connecting channel  51 , which connects the inside space of the connecting box to the inside space of stator housing  3 . Connecting channel  51  gives room for accommodating plug connector  50  as well as for accommodating an additional intermediate circuit capacitor  51 . This intermediate circuit capacitor  51  is dimensioned smaller than the one provided above fastening frame  36 , that is not shown, but is situated closer to power components  32 . 
     Reinforcements  41  extending transversely over the upper side are developed on fastening frame  36 . Consequently, the contact force after screwing on the fastening frame is transmittable onto the printed circuit board, and from this, on further to power components  32 . The latter are thus pressed against contact area  33  and fixed. With that, good heat dissipation of power components  32  is effected over outer housing  2 . 
     A rim  48  is provided on fastening frame  36 , which has tabs  37 . An additional printed circuit board for signal electronics and the rectifier and the intermediate circuit capacitor of the converter may be inserted in rim  48 . When the additional printed circuit board is inserted, tabs  37  snap into lugs  42 , whereby the additional printed circuit board is held in position. The additional printed circuit board is connected electrically to printed circuit board  35  via a fitting plug connector to plug connectors  38 . The additional printed circuit board includes a device for the connection of the power current supply of the converter and a device for the connection of the data communications lines. The rectifier unit and the intermediate circuit capacitor are situated on an additional printed circuit board in the left region, and are protected by front base part  29  of connecting box base  8 , that is designed to be higher, even when connecting box cover  9  is taken off. 
       FIG. 5  shows a schematic view of an additional connecting box  60 , as seen from above. A first plateau surface  61  and a second plateau surface  62  are separated by a bow-shaped end face  68 . Second plateau surface  62 , in this instance, is set down further compared to first plateau surface  61 , and is thus farther away from the observer. Plateau surface  61 ,  62  and end face  68  form a step. At the ends of the bow-shaped region, end face  68  is guided parallel to side area  69 ,  70  of connecting box  60 . In end face  68  openings  64 ,  65 ,  66 ,  67  are provided for the cable passage opening into the inside of connecting box  60 . Openings  64 ,  65 ,  66 ,  67  each have a direction of opening symbolized by arrows. Connecting box  60  has a plane of symmetry  63 , from which openings  64 ,  65 ,  66 ,  67  in each case point away in their directions of opening. Openings  64 ,  65 ,  66 ,  67  each offer the possibility of having a cable passage opening that is protected by second plateau surface  62  and the height of end face  68 . 
       FIG. 6  shows a sectional view of the converter motor of  FIG. 1 , having additional electronic options inside the motor connecting box. 
     On fastening frame  36 , printed circuit board  35 , having the power electronics for motor control, is mounted on the lower side. An additional printed circuit board  80  is mounted on the upper side of fastening frame  36 . On this printed circuit board  80  there are situated at least one control electronics (not shown) for bus communication, a plug connector  83 , a rectifier unit  84  of the converter and an intermediate circuit capacitor  85 . 
     Rectifier unit  84  and intermediate circuit capacitor  85  are designed for voltages of 400 V and more and for high current strengths of 1 A and more, and therefore they have increased structural dimensions. Thus, additional internal space made available by the step in connecting box cover  9  is utilized. 
     Plug connector  83  is arranged to fit an additional plug connector (not shown) on the inside of connecting box cover  9 . This additional plug connector is plugged into plug connector  83  by the mounting of connecting box cover  9  onto connecting box base  8 . Consequently, the connecting line of the converter motor is able to be connected to the additional plug connector via cable terminals. 
     A third printed circuit board  81  is connected to printed circuit board  80 , preferably via a plug connection, whose plug connectors are soldered firmly onto respective printed circuit boards  80 ,  81 . Third printed circuit board  81  is used for reading out motor variables, especially operating measured variables, which are able to be read out for diagnosis via an USB connection  82 . Alternatively, an IR interface or another standard plug connector is provided. 
       FIG. 7  shows a slantwise view of the converter motor of  FIG. 6 . Connecting box cover  9  forms a bow-shaped step and differs from the connecting box cover of  FIGS. 1 to 3  only by an additional opening  90 , behind which a USB connection  82  is situated, for reading out operating measured variables. 
     At the end face of the step, the possible assignments of the openings are shown for cable bushings, as follows: A cable gland  91  for cables having a first diameter, alternatively a cap  93 , a cable gland  92  for cables having a second, lesser diameter, alternatively a cap  94 , and a cable gland  95  for data cable having a diameter that is once more clearly lesser, and alternatively a cap  96 . The arrangement of the cable glands and the caps is only for exemplary purposes, and other combinations are also possible. 
     It has been shown that, for cables having a first and second diameter, which are designed for power current transmission, one each of the openings on the slantwise sides of the step is sufficient to make possible a cable routing to three sides of the converter motor. While maintaining the admissible bending radius of the cables, the offset of the connecting openings permits a cable routing which does not enlarge the interference contour of the converter motor. In the case of the substantially more flexible data cables, however, one terminal pad is sufficient.