Abstract:
The invention relates to a housing ( 2 ) for an electrical machine ( 1 ), said housing comprising a housing wall ( 3 ) having an inner surface ( 4 ). At least two cooling channels ( 15 ) extend inside the housing wall. A connecting deviation channel ( 16 ) is provided between two of the cooling channels ( 15 ). The inventive housing is also provided with an inner sealing ring ( 18 ) applied to the inner surface ( 4 ). The housing wall ( 3 ) comprises at least one housing recess ( 17 ) on the inner surface ( 4 ) thereof, in the region of the inner sealing ring ( 18 ), such that, together with the inner sealing ring ( 18 ), it forms the deviation channel ( 16 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a housing of an electrical machine comprising a housing wall which has an inner surface and within which housing wall at least two cooling channels extend. 
     A housing of this type, designed in particular for liquid cooling of the electrical machine, is used for example as an extruded profile component. The electrical machine can be constructed as an electric motor or else as an electric generator. The cooling channels extend substantially in the axial direction, that is to say in the direction of an axis of rotation of a rotor rotatably mounted within the housing. The deflection of the cooling liquid guided within the cooling channels during operation is carried out at both axial ends of the housing in a bearing shield, in an intermediate flange or by means of a deflection plate. For the purpose of guiding the cooling liquid by deflection, in this case cast-in or subsequently bored channels or pipes are used in the bearing shield or intermediate flange, implemented in particular as a casting. 
     In this implementation, the sealing between the housing on the one hand and the bearing shield, the intermediate flange or the deflection plate on the other hand is normally carried out by surface sealing means. This form of sealing requires considerable expenditure during production and from time to time nevertheless does not lead to satisfactory results. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to specify a housing of the type designated at the beginning which comprises efficient and low-expenditure deflection for the coolant. 
     This object is achieved by a housing of an electrical machine, comprising a housing wall which has an inner surface and within which housing wall at least two cooling channels ( 15 ) extend, wherein
     a) a connecting deflection channel is provided between two of the cooling channels,   b) an inner sealing ring resting on the inner surface is provided, and   c) in the region of the inner sealing ring on the inner surface, at least one housing recess which, together with the inner sealing ring, forms the deflection channel is provided in the housing wall.   

     The deflection provided by the invention renders complicated construction measures or subsequent machining measures on a bearing shield or on an intermediate flange superfluous. Likewise, it is possible to dispense completely with a separate deflection plate. Furthermore, the surface sealing means which, in the prior art, can be implemented only with considerable expenditure from the point of view of process safety, are dispensed with. In contrast, in the housing according to the invention, in particular at least at one lateral axial end, use is made of a simple inner sealing ring which, in conjunction with a recess in the housing wall, which can likewise be produced simply, forms the deflection channel. As a result, the expenditure on fabrication decreases considerably. At the same time, the desired function of the deflection is nevertheless ensured by these simple means. In particular, it is also possible for the seal to be implemented considerably more simply and with higher process safety. 
     One variant is beneficial, in which the housing recess by means of which the deflection channel is formed is so large that it covers the two cooling channels to be connected. The housing recess can in this case be implemented as a milled recess in the housing wall on the inner surface over a certain region in the circumferential direction. The dimensions in the circumferential direction and in the radial direction, that is to say substantially in the direction of the thickness of the housing wall, are determined such that the two cooling channels extending within the housing wall each have an additional opening on account of the housing recess. A housing recess of this type in the form of a milled recess may very easily be introduced subsequently into the housing, which, in particular, is constructed as an extruded profile. 
     Furthermore, the inner sealing ring can also have an annular recess, which likewise contributes to the formation of the deflection channel. In particular, the deflection channel is then formed by means of two housing recesses, preferably like drilled holes, which each cover one of the two cooling channels to be connected, and the annular recess. Both the housing recesses belonging to the opening of the two cooling channels and the annular recess, in particular once more formed as a milled recess, can be produced simply and subsequently. 
     According to another variant, the inner sealing ring rests on the housing wall with a form fit. For instance, it is pressed in, shrunk in or else adhesively bonded in. These measures do not give rise to any great expenditure on fabrication either. 
     The inner sealing ring is preferably formed as a flat ring or as a ring having an L-shaped profile. Both configurations are standard shapes for a ring, which can thus be procured or produced easily. 
     Between the inner sealing ring and the housing wall, on both axial sides of the housing recess, in each case sealing means, in particular in the form of an O-ring, are preferably provided. An O-ring of this type is a familiar sealing means and, in terms of mounting and handling, is considerably simpler than a flat sealing means. 
     In one refinement, in which the inner sealing ring has an L-shaped profile with two limbs, sealing means, once more in particular in the form of an O-ring, are preferably provided in each of the two limbs, for the purpose of sealing with respect to the housing wall. In this refinement, the advantages described above also result on account of the possible use of the standard O-rings. In addition, the L-shaped profile permits the cooling channels and the deflection channel to be terminated and preferably also sealed in the radial and axial direction. 
     Also beneficial is a variant in which, within the housing wall, a winding system having at least one winding overhang is arranged and the inner sealing ring is arranged substantially in the region of the winding overhang. By means of this advantageous measure, deflection is achieved without the (external) dimensions of the electrical machine having to be enlarged, in particular in the axial direction, as is the case for example in the prior art, which provides an additional intermediate flange or an additional deflection plate for the purpose of deflection. The edge dimension is maintained. Increasing the overall length in the axial direction is not necessary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Further features, advantages and details of the invention emerge from the following description of three exemplary embodiments by using the drawing, in which: 
         FIG. 1  shows a first exemplary embodiment of a housing comprising a deflection channel formed by means of a flat ring, in a cross-sectional illustration 
         FIG. 2  shows the housing according to  FIG. 1  in a perspective illustration, 
         FIG. 3  shows a second exemplary embodiment of a housing comprising a deflection channel formed by means of a flat ring, in a perspective illustration, 
         FIG. 4  shows a third exemplary embodiment of a housing comprising a deflection channel formed by means of an L-shaped ring, in a cross-sectional illustration, and 
         FIG. 5  shows the housing according to  FIG. 4  in a perspective illustration. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In  FIGS. 1 to 5 , mutually corresponding parts are provided with the same designations. 
     In  FIG. 1 , an electrical machine  1  in the form of an electric motor having a first exemplary embodiment of a housing  2  is illustrated in cross section. The housing  2 , formed as an extruded profile, has a housing wall  3  with an inner surface  4  which surrounds a hollow cylindrical interior  5 . Arranged in the hollow cylindrical interior  5  is a stator  6  firmly anchored in the housing  2 , and a rotor  8  mounted such that it can rotate about an axis of rotation  7 . The stator  6  comprises stator laminations  9 , within which electric conductors of a winding system  10  extend. In the axial direction, that is to say in the direction of the axis of rotation  7 , the winding system  10  in each case has a winding overhang  11  and  12  on both sides of the stator laminations  9 . The housing  2  is open on both sides in the axial direction. In each case a bearing shield  13  and  14  is provided on the open sides as a termination. 
     The housing  2  comprises a plurality of cooling channels  15 , of which only one is reproduced in the sectional illustration according to  FIG. 1 . The cooling channels  15  extend in the axial direction, substantially parallel to the axis of rotation  7 . Depending on the embodiment, they can be arranged uniformly or grouped in the circumferential direction. In the exemplary embodiment shown in  FIGS. 1 and 2 , their distribution is non-uniform in the circumferential direction. During the operation of the electrical machine  1 , a liquid flows in the cooling channels  15  for the purpose of cooling. 
     In order to conduct this cooling liquid through all the cooling channels  15 , a deflection channel  16  is provided on the side facing the right-hand bearing shield  13 , between two adjacent cooling channels  15  in each case. On the side of the left-hand bearing shield  14 , on the other hand, the deflection is carried out by means of pockets provided in the bearing shield  14  but not specifically shown. The deflection channel  16  is formed by means of a housing recess  17  and a closing inner sealing ring  18 . The housing recess  17  is, for example, a simple milled recess in the housing wall  3 , on the inner surface  4 . Its depth is so great that, starting from the inner surface  4 , it reaches as far as the two cooling channels  15  to be connected. The inner sealing ring  18  is formed as a flat ring in the exemplary embodiment of  FIG. 1  and covers the housing recess  17  completely. It is connected to the inner surface  4  via a form fit. In the exemplary embodiment, it is shrunk in. In addition, in the axial direction on both sides of the housing recess  17 , between the inner sealing ring  18  and the housing wall  3 , in each case an O-ring  19  and  20  is provided for the purpose of sealing with respect to emergence of liquid into the hollow cylindrical interior  5 . This seal therefore acts primarily in the radial direction. 
     Sealing elements  21  and  22  are also provided at the connecting point between the housing  2  and the laterally adjacent bearing shields  13  and  14 . By way of example, in the exemplary embodiment of  FIG. 1 , the left-hand and the right-hand bearing shields  13  and  14  are in each case formed in a different way with respect to emergence of liquid from the cooling channels  15 . The respective design of these seals, primarily acting axially, can be chosen as required, for example also as a flat seal. In particular, the sealing elements  21  and  22  are matched to the cross-sectional area of the cooling channels  15  and are thus preferably designed to be relatively small and circular. 
     The configuration of the deflection channel  16  by means of the housing recess  17  and the inner sealing ring  18  is particularly simple and nevertheless very effective. It can be implemented with relatively little technical expenditure and nevertheless offers high process safety. In addition, it is beneficial that the deflection channel  16  is arranged in the region of the winding overhang  12  which is present in any case, so that, because of the deflection channel  16 , no increase in the dimension in the axial direction is necessary. In this beneficial embodiment of the deflection channel  16 , the external dimensions of the electrical machine  1  therefore remain completely unchanged. 
     In  FIG. 2 , the housing  2  is reproduced perspectively. The flat inner sealing ring  18  is illustrated as cut open at one point in order to make visible the deflection channels  16  located beneath with the housing recesses  17  for connecting two adjacent cooling channels  15  in each case. Deflection channels  16  that are adjacent in the circumferential direction are in each case separated from one another by a dividing web  24 . 
     In  FIG. 3 , a further exemplary embodiment of a housing  25  is shown, which is likewise configured as an extruded profile and, in its housing wall  3 , comprises a plurality of cooling channels  15  extending axially and arranged distributed in the circumferential direction. At least on the one open side shown, the housing  25  is provided with an inner sealing ring  26 , once more designed as a flat ring, by means of which deflection channels  27  are formed between two of the adjacent cooling channels  15  in each case. As distinct from the exemplary embodiment according to  FIGS. 1 and 2 , housing recesses  20  are provided in the form of drilled holes, which each extend from the inner surface  4  as far as one of the cooling channels  15 . In addition, on its side facing the inner surface  4 , the inner sealing ring  26  comprises annular recesses  29  which, for example, are milled into the inner sealing ring  26 . The deflection channels  27  in this second exemplary embodiment are therefore formed in each case by means of two housing recesses  28  like drilled holes and a milled annular recess  29 . The sealing is carried out in a way analogous to the first exemplary embodiment. 
     In  FIGS. 4 and 5 , a third exemplary embodiment of an extruded housing  30  having an L-shaped inner sealing ring  31  for forming deflection channels  32  is illustrated. The housing  30  is part of an electrical machine  33 , which is likewise designed as an electric motor. 
     The deflection channels  32  in this third exemplary embodiment comprise housing recesses  34 , which are milled in on the inner, surface  4  in a lateral edge region  35  of the housing wall  3 . As constituent parts of the housing wall  3  which are not removed by the respective milled recesses, there are dividing webs  36  between the individual deflection channels  32 . By means of the two limbs of the L-shaped inner sealing ring  31 , the deflection channels  32  are closed both in the radial and in the axial direction, and the cooling channels  15  are closed in the axial direction. For the purpose of sealing, in each case an O-ring  37  or  38  is provided between each of the two limbs and the housing wall  3 . The L-shaped inner sealing ring  31  therefore acts radially and axially in a closing and sealing manner. As a result, the sealing means otherwise required in the bearing shield  13  to seal the cooling channels  15  axially can be dispensed with in the third exemplary embodiment. In principle, a configuration having annular recesses on the inner sealing ring  31 , comparable to those of the second exemplary embodiment according to  FIG. 3 , is also conceivable in the third exemplary embodiment.