Abstract:
The invention relates to a cooling device ( 1,2 ) pertaining to an electrical machine ( 10 ), said cooling device ( 1,2 ) comprising at least one rod-shaped heat-conducting means ( 3,4 ) for heat-conductive connection to the electrical machine ( 10 ). The invention also relates to an electrical machine ( 10 ) comprising a housing ( 18 ) and/or a stator ( 14 ), said housing ( 18 ) and/or stator ( 14 ) being applied to a cooling device ( 1,2 ) comprising a rod-shaped heat-conducting means ( 3,4 ) extending axially in relation to the electrical machine. Said heat-conducting means ( 3,4 ) is to be received by the stator ( 14 ) and/or the housing ( 18 ) or arranged on the stator ( 14 ) and/or the housing ( 18 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a cooling device for an electrical machine or to the electrical machine itself and to a cooling system for an electrical machine. 
     In an electrical machine, heat losses occur during operation which need to be dissipated by a corresponding cooling system or a corresponding cooling device. In order to cool the electrical machine, for example, cooling systems or cooling devices can be used which operate with cooling air, cooling water or heat pipes. Such cooling systems or cooling devices are integrated in the electrical machine, each electrical machine having a cooling device, which is designed for this electrical machine. 
     DE 42 42 132 has disclosed, for example, an electrical machine which is air-cooled. One disadvantage with such an electrical machine is the fact that the cooling device is designed irrespective of the thermal load on the electrical machine at the use location of the electrical machine. The thermal load on the electrical machine is, for example, dependent on the operating states to be expected of the electrical machine, the operating states being reflected, for example, in alternations of load. The cooling device is designed for the most problematic operation case of the electrical machine without taking into consideration the fact that some, possibly critical, alternations of load of the electrical machine are not necessary for a specific use of the electrical machine. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to specify a cooling device for an electrical machine with the aid of which the cooling power can be matched as required. 
     According to one aspect of the present invention, the object is achieved by a cooling device having at least one rod-shaped heat-conducting means, the rod-shaped heat-conducting means being provided for the thermally conductive connection to the electrical machine. 
     According to another aspect of the present invention, the object is achieved by an electrical machine which has a housing and/or a stator, wherein the housing and/or the stator is provided for fitting a cooling device, which has heat-conducting means running axially with respect to the electrical machine. 
     According to yet another aspect of the present invention, the object is achieved by a cooling system for an electrical machine, which can be cooled by means of a cooling device, wherein a mechanical interface is formed between the electrical machine and the cooling device and makes it possible to use various cooling devices with different cooling effects and/or different cooling means. 
     A cooling device for an electrical machine has at least one rod-shaped heat-conducting means, the rod-shaped heat-conducting means being provided for the thermally conductive connection to the electrical machine. Heat can be conducted out of the electrical machine into the cooling device from the rod-shaped heat-conducting means. For the purpose of emitting the heat, the cooling device has a heat sink for convection cooling, for example, and/or a connection to a coolant such as, for example, a liquid or air as a gaseous coolant. The electrical machine is thus cooled. The rod-shaped heat-conducting means is, for example, a heat pipe, a rod consisting of a solid material (i.e. not hollow) or else a hollow rod, in which a coolant can be conducted. 
     The rod-shaped heat-conducting means can therefore guide the heat axially, for example, out of a hot region of the stator of the electrical machine and emit the heat to a heat sink or a coolant. The heat sink can be cooled particularly effectively for example by an air flow produced by a fan. When using liquid cooling (for example water cooling) it is advantageous if, for example, the water is guided directly into the heat-conducting elements and also guided back. 
     In one advantageous configuration, the electrical machine is designed such that it has accommodating channels for the rod-shaped heat-conducting means. The accommodating channels are, for example, within a stator laminate stack of the electrical machine and/or within a housing of the electrical machine, the accommodating channels being open towards a front end of the stator. Advantageously, the accommodating channels extend axially over a large proportion of the axial extent of the stator. The rod-shaped heat-conducting means advantageously fill a large proportion of the accommodating channels. If the cooling device is fitted to the electrical machine, the cooling device can be regarded as part of the electrical machine. 
     In a further configuration of the invention, the electrical machine is designed to be compatible with at least two cooling devices such that the electrical machine has such a large number of accommodating channels that it is provided and is suitable for accommodating both a first cooling device and for accommodating a second cooling device, the first cooling device having a number of rod-shaped heat-conducting means which is different than that of the second cooling device. The stator of the electrical machine and/or the housing of the electrical machine therefore has a number of accommodating channels which can go beyond the number of rod-shaped heat-conducting means of different cooling devices. A modular use of cooling devices having different cooling effects is therefore possible on one and the same stator or housing of the electrical machine. The cooling power required for an electrical machine in its respective area of use can therefore be achieved by selecting a specific cooling device from a number of different cooling devices with different cooling powers. 
     Different cooling powers can also be achieved by different cooling concepts in the cooling device. Cooling devices can be designed for water cooling or air cooling, for example. Since the stator and/or the housing of the electrical machine to be cooled only has to ensure that the rod-shaped heat-conducting means are accommodated, an electrical machine having a specific design can be cooled using different cooling concepts. 
     The rod-shaped heat-conducting means can be provided not only for being accommodated in accommodating channels in the stator and/or in the housing of the electrical machine. In an advantageous configuration of the electrical machine, the rod-shaped heat-conducting means bear against an outer side of the stator and/or the housing of the electrical machine. If the rod-shaped heat-conducting means are provided for the purpose of them bearing against a surface of the stator and/or of the housing of the electrical machine, this is more cost-effective than the use or production of accommodating channels within the stator or the housing of the electrical machine. The electrical machine can not only be designed as a motor with rotary operation but also as a linear motor. In linear motors, there is no axis of rotation in accordance with which the alignment of the rod-shaped heat-conducting means could take place. For this reason, the rod-shaped heat-conducting means in a linear motor are aligned, for example, along a movement axis or at right angles to a movement axis. 
     The invention has the advantage of, if necessary, optimum focusing of the cooling. This relates in particular to electrical machines without a housing which are air-cooled. In electrical machines without a housing, until now dedicated cooling over the surface of the electrical machine has been known, for example. For improved cooling, an enlarged cooling area is required on the electrical machine. Disadvantageously, this increases the physical dimensions of the electrical machine. 
     In a further advantageous configuration, the rod-shaped heat-conducting means is provided for an axial alignment with respect to the electrical machine. In a rotary electrical machine, the axis of the axial alignment is the axis of rotation. If, therefore, the cooling device of the electrical machine is at the installation location or at the attachment location on the electrical machine, the rod-shaped heat-conducting means is aligned approximately parallel to the axis of the electrical machine, which is in particular a rotary electrical machine. A largely parallel alignment with respect to the axis is referred to as an axial alignment. The use of the axial alignment makes it possible for the rod-shaped heat-conducting means to be capable of reaching over a wide region of the longitudinal axis of the electrical machine. This has the advantage that the electrical machine can emit heat to the heat-conducting means to the greatest possible extent over its entire longitudinal region. 
     Advantageously, at least one cooling device is fitted in the region of a mounting plate of the electrical machine. Furthermore, the electrical machine can also be designed such that it has two cooling devices, in each case one cooling device being positioned in the region of the front end of the rotary electrical machine. 
     In a further advantageous configuration, the cooling device has a plurality of rod-shaped heat-conducting means, these advantageously being distributed largely symmetrically with respect to the axis of rotation of the electrical machine. Owing to the largely symmetrical distribution, it is possible to achieve a situation in which the heat is transported away uniformly. 
     In a further embodiment of the cooling device, the rod-shaped heat-conducting means can be fitted in a stator of the electrical machine and/or in a housing of the electrical machine and/or on an outer face of the electrical machine. Both when it is fitted in a stator or in a housing of the electrical machine and when it is fitted on the outer face of the electrical machine, the rod-shaped heat-conducting means is in contact with these corresponding parts. This contact makes it possible for thermal energy to be transmitted. The transmission can be improved, for example by the use of heat-conducting paste. Then, in an advantageous configuration, heat-conducting paste is located between the rod-shaped heat-conducting means and the stator or the housing or an outer face of the electrical machine. The greater the contact area between the stator, the housing or the outer face of the electrical machine and the rod-shaped heat-conducting means, the better the cooling power is. 
     In a further advantageous configuration, the rod-shaped heat-conducting means is hollow. For example cooling air or cooling liquid can be conducted in the cavity. With the aid of this coolant (cooling air or cooling liquid), thermal energy can be dissipated from the electrical machine. In a further advantageous configuration, the cavity is split into at least two cavities by means of a separating means, such as a partition wall, for example, the cavities being connected to one another at least partially. In this way, a forward channel and a return channel can be formed for the coolant within the rod-shaped heat-conducting means. 
     A further advantageous configuration results if the cooling device can be plugged onto an electrical machine. A cooling device which can be plugged on has the advantage that it can be replaced relatively easily. Advantageously, the rod-shaped heat-conducting means act as guide pins for the plug-in connection between the cooling device and the electrical machine. For this purpose, the electrical machine has, for example, the accommodating channels in the stator and/or the housing of the electrical machine. The rod-shaped heat-conducting means can be introduced into the accommodating channels. 
     In a further advantageous configuration, the rod-shaped heat-conducting means have a conical design. Owing to the conical design, the procedure for plugging the cooling device onto the electrical machine is facilitated. Advantageously, in the case of a conical design of the rod-shaped heat-conducting means, the accommodating channel in the stator or in the housing of the electrical machine also has an inverse conical shape matching the rod-shaped heat-conducting means. 
     The object of the invention is achieved in the case of an electrical machine (in particular a rotary electrical machine) which has a housing and/or a stator, the housing and/or the stator being provided for fitting a cooling device which has heat-conducting means running axially with respect to the electrical machine. In order to fit the cooling device, the heat-conducting means can be sunk into accommodating channels of the stator or of the housing. The accommodating channels advantageously extend over a large proportion of the region of the stator or of the housing in the longitudinal direction. The longitudinal direction is predetermined by the axis of rotation of the electrical machine. The electrical machine has, for example, a large number of channels. Depending on the cooling power required for an application case of the electrical machine, cooling devices of different types can then be used. The cooling devices may correspond to one of the above-described embodiments. As a result of the fact that different cooling devices can be used for an electrical machine, a cooling system is formed. 
     In one advantageous configuration, various types of cooling devices can also be used. It is also possible to build up a cooling system from this. In a cooling system for an electrical machine which can be cooled by means of a cooling device, a mechanical interface is formed between the electrical machine and the cooling device and makes it possible to use various cooling devices with different cooling effects and/or different cooling means. If the cooling device uses, for example, cooling air for cooling purposes, the use of the cooling air is a favorable means for cooling an electrical machine. A higher cooling power is made possible by the use of a cooling liquid. The use of a cooling liquid in turn has the consequence, however, that there is greater complexity owing to the risk of leaks occurring. 
     In an advantageous configuration of the electrical machine, the machine has a large number of channels for accommodating rod-shaped heat-conducting means. Depending on the direct cooling power, various types of cooling devices can then be connected. If the electrical machine has, for example, 20 channels, cooling devices can be used which have, for example, 4, 8, 12, 16, 20 or else any other number between 1 and 20 of rod-shaped heat-conducting means. The rod-shaped heat-conducting means are plugged into the accommodating channels. The greater the number of rod-shaped heat-conducting means, the greater the potential thermal energy is which can be dissipated by the cooling device. A flexible cooling system for cooling an electrical machine is thus specified, a uniform interface between the electrical machine and the cooling device making it possible to use various cooling devices with different cooling powers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The invention will be explained in more detail with reference to the exemplary embodiments illustrated in the drawing, in which: 
         FIG. 1  shows a rotary electrical machine with a cooling device, 
         FIG. 2  shows a first type of cooling device, 
         FIG. 3  shows a further type of cooling device, 
         FIG. 4  shows a further type of cooling device, which has a partition wall, 
         FIG. 5  shows a section through the cooling device shown in  FIG. 4 , 
         FIG. 6  shows a further section through the cooling device shown in  FIG. 4 , 
         FIG. 7  shows a further type of cooling device, which has two partition walls, 
         FIG. 8  shows a further type of cooling device, which has a pipe-in-pipe system, 
         FIG. 9  shows a further type of cooling device, which has a rod-shaped heat-conducting means, which bears against the housing of the electrical machine, 
         FIG. 10  shows a section through the cooling device shown in  FIG. 9 , 
         FIG. 11  shows a further type of cooling device, 
         FIG. 12  shows a section through the cooling device shown in  FIG. 11 , 
         FIG. 13  shows a linear motor with a cooling device; and 
         FIG. 14  shows a section through a modified cooling device. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The illustration shown in  FIG. 1  shows an electrical machine  10 . The electrical machine  10  is a rotary electrical machine without a housing and having an axis  12 . Furthermore, the electrical machine  10  has a shaft  16  and a stator  14 . Accommodating channels  5  are provided in the stator  14 . The accommodating channels  5  are used for accommodating rod-shaped heat-conducting means  3 . The illustration shown in  FIG. 1  also shows a cooling device  1 . The cooling device  1  has connections  24  and  25 . The connections are used, for example, for accommodating or emitting cooling liquid or else cooling air. Furthermore, the cooling device  1  has rod-shaped heat-conducting means  3 . The rod-shaped heat-conducting means  3  are designed such that they can be introduced into the accommodating channels  5 . In a further configuration, which is not illustrated in  FIG. 1 , however, the stator  14  has the rod-shaped heat-conducting means  3 , the rod-shaped heat-conducting means  3  protruding out of a front end  15  of the electrical machine  10 , a cooling device  1  being capable of being placed onto the protruding parts of the rod-shaped heat-conducting means  3 . 
     The electrical machine  10  in  FIG. 1  therefore has accommodating channels  5  as axial cutouts at suitable points on its front end  15 . Suitable points are, in particular, those which are not provided for guiding a magnetic flux. The axial cutouts, which can be produced, for example, by means of a drilled hole, do not impair the normal operation of the electrical machine  10  without cooling. If required, the cooling device  1  can then be placed axially onto an operating side  15  of the electrical machine and fixed in a suitable manner. The cooling device  1  has a number of rod-shaped heat-conducting means  3  which corresponds to the number and shape of the cutouts, these heat-conducting means, preferably provided with a heat-conducting paste, dipping precisely into these cutouts. 
     The illustration shown in  FIG. 2  shows a detail of a stator  14 , in which a rod-shaped heat-conducting means  3  is located. The rod-shaped heat-conducting means protrudes beyond the front end  15  of the stator  14 . A cooling channel  20  is placed on the protruding section of the rod-shaped heat-conducting means  3 . The cooling channel  20  is provided, for example, for guiding cooling liquid. A possible direction of flow  21  of the cooling liquid is illustrated by an arrow. The rod-shaped heat-conducting means  3  protrudes into the cooling channel  20  and, in the process, has cooling liquid flowing around it, with the result that heat dissipation can be realized. 
     The illustration shown in  FIG. 3  shows a further embodiment of possible heat dissipation. The rod-shaped heat-conducting means  3  is located in a stator  14 , which is illustrated as a detail. The rod-shaped heat-conducting means  3  protrudes out of the stator  14 . A heat sink  22  is placed on the protruding part of the rod-shaped heat-conducting means  3 . The heat dissipation from the rod-shaped heat-conducting means  3  into the heat sink  22  is achieved in a particularly advantageous manner by the use of a heat-conducting paste  23 . 
     The illustration shown in  FIG. 4  shows a further possibility for cooling the stator  14 . A pipe  35  is introduced into the stator  14 . The pipe  35  is a possible embodiment of the rod-shaped heat-conducting means. The cooling channel  20  is plugged onto the pipe  35 , with the result that, for example, a cooling liquid can be conducted directly through said cooling channel  20 . The pipe  35 , which is closed at one end, and the cooling channel  20  are split by a separating means  29  such that a coolant is guided from the cooling channel  20  into a first half of the pipe  35 , and the coolant is guided into a second half of the pipe  35  at a base  45  of the pipe  35 . The separating means  29  is a type of wall, which divides the pipe  35  into a first half and a second half, the wall reaching from the cooling channel  20  almost up to the base  45  of the pipe  35 . The first half forms a channel  70  and the second half forms a channel  71 . The base  45  is therefore spaced apart from the separating means  29 . The separating means  29 , which is manufactured, for example, from sheet metal, is arranged within the cooling channel  20  such that the coolant is conducted partially or completely into the pipe  35 . In the illustration shown in  FIG. 4 , a direction of flow of coolant is illustrated by means of arrows  27 , a forward flow being formed by the channel  70  and a return flow being formed by the channel  71 . The pipe  35  has been plugged into the stator  14  either in communication with the cooling channel  20  or else separate from it, with the result that, once the pipe  35  has been plugged into the stator  14 , the cooling channel  20  is then plugged onto that part of the pipe  35  which protrudes beyond the front end  15  of the stator  14 . 
     The illustration shown in  FIG. 4  also shows two sectional planes V and VI. The sectional plane V is illustrated in  FIG. 5  and shows a cross section of the pipe  35 . The pipe  35  is split into two channels  70  and  71  by the separating means  29 , which acts as a type of wall. The direction of flow of the coolant is indicated by circles. The sectional plane VI, which is illustrated in  FIG. 6 , shows a plan view  37 . In this sectional plane VI it is shown that the separating means  29  does not reach up to the base of the pipe  35 , with the result that there is a connection between the forward flow and the return flow. Furthermore, a wall  33  of the cooling channel  20  is also shown. 
     The illustration shown in  FIG. 7  shows a further embodiment of a pipe  35 , which is introduced into a stator  14  as a rod-shaped heat-conducting means. The pipe  35  now has two separating means  29  and  30 , the separating means being in the form of partition walls, as was already the case in  FIG. 4 . The connection of the pipe  35  again takes place by a cooling channel  20 . A cooljet  39  is used for introducing a coolant into the pipe  35 . The profile of the direction of flow of coolants (gaseous or liquid)  27  is also illustrated in  FIG. 7  by means of arrows  27 . 
     The illustration shown in  FIG. 8  shows a pipe  35 , into which an injection pipe  41  is introduced. The injection pipe  41  leads into the region of the base  45  of the pipe  35 . The injection pipe not only protrudes into the pipe  35  but also into the cooling channel  20 . In this case, the positioning of the injection pipe  41  into the cooling channel  20  is implemented such that the injection pipe  41  takes up the cooling liquid in the region in which the coolant is supplied. The injection pipe  41  is sealed off from the cooling channel  20  by means of a seal  43 . 
     The illustration shown in  FIG. 9  shows a housing  18  of an electrical machine, which is not illustrated in any more detail. A rod-shaped heat-conducting means  4  bears against the housing  18 . In particular corners of the housing and/or of the stator of the electrical machine are suitable for this purpose. The rod-shaped heat-conducting means  4  is fixed to the housing  18 , for example, via a toothed portion  49 , the illustrated toothed portion being a dovetailed connection. The rod-shaped heat-conducting means  4 , which have a base  46 , is designed such that it does not reach up to a housing end  19 . This is shown in  FIG. 10 ,  FIG. 10  illustrating a section X from  FIG. 9 . As illustrated in  FIG. 10 , the base  46  therefore ends in front of the housing end  19 . Furthermore, the base  46  is flattened obliquely such that easier access to a fixing means  47  is possible. The fixing means  47  is, for example, a drilled hole, which is used for fixing the housing  18  on a base plate. As shown in  FIG. 14 , the base  46  of the rod-shaped heat-conducting means  4  and the housing end  19  can have matching tapered configuration. The illustration shown in  FIG. 11  shows a further embodiment of the cooling device  2 . A rod-shaped heat-conducting means  3  is located in the stator  14  of an electrical machine  10 . The rod-shaped heat-conducting means  3  is in the form of solid material and consequently does not have a cavity. The rod-shaped heat-conducting means  3  protrudes out of the stator  14 . A cooling device is placed onto the rod-shaped heat-conducting means  3 . The cooling device has a fan  51 . The fan  51  has a fan motor  55 . Cooling air can be sucked by means of the fan  51 . The profile of the cooling air is illustrated by arrows  27 . The cooling air is guided to the rod-shaped heat-conducting means  3  via channels  72 , only one rod-shaped heat-conducting means  3  being illustrated in  FIG. 8 , but it being possible for a plurality to be provided on the electrical machine  10 . The rod-shaped heat-conducting means  3  is placed onto a cooling grating  75 , which is illustrated in detail in  FIG. 12 .  FIG. 12  shows a section XII from  FIG. 11 . The cooling grating  75  illustrated in  FIG. 12  has cooling air channels  59  and cooling ribs  57 . The rod-shaped heat-conducting means  3  is now placed onto the cooling grating  75  such that the rod-shaped heat-conducting means  3  emits heat to the cooling ribs  57 , it being possible for heat to be emitted, via the cooling ribs  57 , to cooling air which is guided past it and can be driven by means of the fan. 
     The illustration shown in  FIG. 13  shows a linear motor  64 , which has a primary part  60  and a secondary part  62 . The primary part  60  has accommodating channels  5 . The accommodating channels  5  serve the purpose of accommodating rod-shaped heat-conducting means  3  of a cooling device  1 . The illustration shown in  FIG. 13  shows that the cooling device according to the invention can be used not only in rotary electrical machines but also in linear motors. Furthermore, it can be seen from  FIG. 13  that an axial alignment of the rod-shaped heat-conducting means  3  is not necessary or advantageous in every case, and therefore another alignment is also possible.