Abstract:
The aim of the invention is to provide a fluid-cooled electric machine in a simple manner. To achieve this, a housing ( 1 ) is configured in two parts, in such a way that each housing part ( 2, 3 ) comprises a bearing bracket ( 4, 5 ) and said housing parts are designed ( 2, 3 ) to form cooling channels once assembled.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to an electrical machine, which has a housing, which has a stator with laminate layers, a rotor, whose shaft is mounted such that it can rotate via bearings positioned in bearing plates, and a liquid casing in the housing having meandering cooling channels.  
         [0002]     In order to increase the power and torque, the principle of liquid or water cooling is used in electrical machines. In liquid-cooled electrical machines, in this case different principles of liquid cooling are used. The liquid permeates an extruded profile which is equipped with axial cooling channels, usually in the corner regions. The deflection of the liquid flow takes place in the separate bearing plates or by means of additional deflecting plates, which are fitted on the outside on the electrical machine.  
         [0003]     Deflection in the bearing plates takes place by means of cast-in or drilled channels, and some of the tubes are also cast into the castings at the same time. Sealing at the bearing plates or deflecting plates takes place, owing to the construction, predominantly by means of surface sealing means, for example a flat gasket or fluids, and for this reason has an extremely complex design.  
         [0004]     One further principle for cooling an electrical machine is inserting a cooling coil into grooves in the rear of the stator which are arranged in annular or meandering fashion. This results in complex fitting, and the heat transfer from the stator to the cooling coil is insufficient.  
       SUMMARY OF THE INVENTION  
       [0005]     Furthermore, an arrangement of cooling collars around the housing of an electric motor is also known. The production of these cooling collars is very complex; the heat transfer from the heat sources of the electrical machine to the cooling collars is likewise extremely deficient.  
         [0006]     Accordingly, the invention is based on the object of providing an electrical machine having liquid cooling which provides sufficient cooling in a simple manner given simple fitting of the individual parts.  
         [0007]     In addition, the intention is to provide reliable sealing of the cooling cycle.  
         [0008]     This object is achieved by an electrical machine having a housing, which has a stator with laminate layers, a rotor, whose shaft is mounted such that it can rotate via bearings positioned in bearing plates, a liquid cooling system in the housing with cooling channels, the housing having a two-part design such that each housing part has a bearing plate and the housing parts are designed such that the housing parts, when assembled, form these cooling channels.  
         [0009]     Owing to the inventive design of the two bearing plates, a coolant flow is passed in the form of a coil or in meandering fashion around the stator, the number of sealing points to adjoining components being minimized. The comparatively effective thermal coupling to the stator results in an increase in the utilization of the electrical machine.  
         [0010]     According to the invention, there is a reduction in the components of the housing, and no deflecting plates are required, as well as additional cooling coils or cooling collars. The fitting time for the electrical machine according to the invention is reduced owing to the omission of the comparatively complex surface sealing means, the fitting of the housing and possibly the cooling coils or cooling collars.  
         [0011]     It is likewise superfluous to cast tubes into the bearing plates as well as to drill or cast the deflecting channels into the bearing plates.  
         [0012]     Owing to the reduction in the sealing points and the changeover associated therewith from surface sealing to radially sealing O rings, higher pressures are possible in the cooling cycle, which in turn has a positive effect on the utilization of the electrical machine.  
         [0013]     Owing to the design of the outer contour of the electrical machine as a cross profile, the comer regions are free, with the result that free access to fixing screws on the flange is possible from the rear of the electrical machine. A realization of round or octagonal outer contours is also possible, which likewise allow access to the fixing screws on the flange. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0014]     The invention and further advantages in accordance with the dependent claims will be explained in more detail with reference to the schematically illustrated embodiments in the drawing, in which:  
         [0015]      FIG. 1  shows a longitudinal section of a housing,  
         [0016]      FIG. 2  shows a cross-sectional view of the housing,  
         [0017]      FIG. 3 ,  FIG. 4  show perspective illustrations, and  
         [0018]      FIG. 5  shows a further longitudinal section of a housing. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]      FIG. 1  shows, in a longitudinal section, a housing  1  according to the invention of an electrical machine having a stator  11  and a rotor  12 . Two housing parts  2  and  3 , which are pushed one inside the other in the manner of a tube, form the housing  1 . Each housing part  2 ,  3  has in each case one bearing plate  5 ,  4 , into which a bearing  9  is inserted and can be positioned by means of, for example, a collar  14 . In this case, the collar  14  is preferably part of a shaft  13 , but can also be fitted to the shaft  13  as an additional part. The shaft  13  bears a rotor  12 . The housing part  2 ,  3  and the respective bearing plate  4 ,  5  preferably each have an integral design.  
         [0020]     The sealing points provided between the housing parts  2  and  3  in the pushed-together state are sealed via O rings  6  and  7 . The tube of the respective housing part  2 ,  3  extends axially over the stator  11 , preferably even far over the respective end windings  15 . In order to make it easier to fit the stator  11 , the housing part  3  is advantageously designed to be slightly conical on its inner side  16 . The cavity thus formed can be filled with thermally conducting materials in order to maintain sufficient thermal conductivity between the housing and the stator  11 .  
         [0021]     As shown in  FIG. 2 , a cooling jacket is provided by the housing parts  2  and  3  being assembled. Axial cooling channels  8  are provided by the housing parts  2 ,  3  being plugged together by the respective pins  15  of the housing parts  2 ,  3 , which are arranged offset, engaging in the respective interspaces  16 . A deflection  10  of these cooling channels  8  takes place owing to the housing parts  2  and  3 , which have been joined together, by the axial extent of the pins  15  being smaller than the axial extent of the interspaces  16 . The pins  15  therefore do not reach up to the end of the respective interspaces  16 .  
         [0022]     Only two sealing points, which are to be sealed off from the outside and are sealed off by O rings  6 ,  7 , are therefore provided. This housing  1  with an integrated cooling jacket is created in a cost-effective manner by means of diecastings. The two sealing points which are provided with the O rings  6  and  7  are preferably machined.  
         [0023]     As an alternative to this, the cooling channels  8  can be incorporated in one or both housing parts  2 ,  3 , for example with the cuttings being detached. It is thus also possible for cooling channels to be provided which are in the form of coils.  
         [0024]      FIG. 3  shows, in a half-assembled state, the housing parts  2  and  3  during fitting. In the assembled state shown in  FIG. 4 , the housing parts  2  and  3  are plugged one inside the other and form the cooling channels  8  with a functional cooling jacket, which is constructed to be meandering when viewed in the circumferential direction, and its deflections  10 .  
         [0025]     The cooling liquid is passed in via the inlet  17  and out via the outlet  18 . The inlet  17  and the outlet  18  are drilled holes, which are connected to the cooling channels  8  in terms of flow such that, for example, a meandering profile of the cooling channels  8  in a circumferential direction results. In this case, a pin between the inlet  17  and the outlet  18  is advantageously designed such that it has the same axial length as the interspace  16  and therefore forms a wall  21 . A flow short circuit between the inlet  17  and the outlet  18  is therefore avoided.  
         [0026]      FIG. 4  shows the electrical machine in the assembled state. In this case, the housing  1  is characterized by a cross profile, with the result that the corner regions are free. Free access to the fixing screws received in respective bores  19  on the flange is therefore possible from the rear of the electrical machine. A realization of round or octagonal outer contours of the housing  1  is likewise possible, which likewise allow access to the fixing screws on the flange.  
         [0027]      FIG. 5  shows, in one further embodiment, a housing  1  according to the invention having a cooling coil  24 . The cooling coil  24  has cooling liquid applied to it via its connections  22 ,  23 . To supplement the general description of the electrical machine shown in  FIG. 1 , in this case cooling takes place by means of a cooling coil  24 . This cooling coil  24  results according to the invention by the housing parts  2 ,  3  being joined together axially. In this case too, the sealing points provided between the housing parts  2  and  3  are sealed off in the pushed-together state via O rings  6  and  7 . There are therefore again only two sealing points. The tube of the respective housing part  2 ,  3  extends axially over the stator  11 , preferably even far over the respective end windings  15 . In order to make it easier to fit the stator  12 , the housing part  3  is advantageously designed to be slightly conical on its inner side  16 . The cavity thus formed can be filled by thermally conducting materials in order to maintain sufficient thermal conductivity between the housing and the stator  12 .  
         [0028]     Such a design is particularly advantageous for axially short electrical machines, in the case of which the axial length corresponds to approximately x times the diameter of the stator  11 , where 0&lt;x&lt;5. This applies primarily to built-in motors, in particular in the case of machine tools.  
         [0029]     The design principle according to the invention of the two housing parts  2 ,  3 , which are to be plugged one inside the other in the form of a tube, can also be modified in the case of air-cooled electrical machines in order to ensure a simple design and a predetermined degree of protection for the electrical machine.