Abstract:
The present invention provides a high-pressure blower comprising a fan arrangement which includes a fan, and a fan housing for conveying working air. An electromotor drives the fan via a motor shaft to provide motor self-ventilation by generating a cooling air stream flowing through the motor due to a cooling wheel driven by the rotor. A wall section separates the interior space of the fan housing accommodating the fan airtight from the interior space of the blower accommodating the electromotor so that the cooling air stream flowing through the electromotor is separated and independent of the air flow of the working air conveyed to the fan.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a blower, especially high-pressure blowers, comprising of a fan arrangement consisting of a fan and a fan housing for conveying working air. The invention moreover relates to a cooling arrangement for an electromotor with means for motor self-ventilation accomplished by generating a cooling air stream flowing through the motor, especially by means of a cooling wheel provided on the rotor. 
   BRIEF SUMMARY OF THE INVENTION 
   For self-ventilating an electromotor, it is well known to attach a small cooling wheel, in the manner of an axial fan, on the rotor of the electromotor so that the cooling wheel, which rotates with the rotor, will generate a cooling air stream flowing through the motor while the rotor rotates. 
   Electronically commutated DC motors, in which motor electronics control the commutation of the winding currents collectorless, are often used today. Some of the electronic components of the motor electronics, especially power semiconductors, generate heat through dissipation power, so that cooling measures are indicated in this area. 
   Thus DE3842588A1 describes an example of such a collectorless external rotor motor with a semiconductor cooling arrangement, the power semiconductors being electrically connected to a printed circuit board but themselves being arranged on a cooling attachment shaped like a flat ring. The cooling attachment thereby indirectly connects the power semiconductors heat-conducting with a motor flange so that the heat from the motor flange is lost to the surroundings. Together with the circuit board and a supporting element fastening the circuit board, the cooling attachment forms a pre-assembled subassembly, which is attached in the vicinity between the motor flange and the open side of the external rotor bell. However, a special cooling air stream is not described. 
   DE4122529A1 likewise describes an electronically commutated driving motor. A printed circuit board containing components of the motor electronics is accommodated in a space between a disk-shaped carrier (motor flange) and an external lid mounted on the side opposite the motor. To eliminate the heat arising from the commutation, the carrier is supposed to demonstrate a ring wall enclosing the rotor externally. This ring wall consequently functions as a cooling attachment by enlarging the surface of the carrier. However, a special cooling air stream is not described here either. 
   One problem that the present invention is intended to solve consists of creating a cooling arrangement as described in the introduction that generates a cooling air stream and also ensures effective cooling of heat-generating components of the motor electronics. 
   The invention furthermore solves the problem that for known fans, such as described in DE10160820A1, there occurs a mixture of the cooling air stream with the blown-off current of working air, because a portion of the air that cools the motor and the electronics is taken from the air current of the fan. This results in dirty air being conveyed over the electronics and through the motor. 
   The present problem is solved according to invention, in that a housing accommodating the electromotor is connected with the blow-off housing in such a manner that the working air stream is separated from the cooling air stream flowing in the electromotor housing, and the cooling air stream escapes through holes in the peripheral wall of the electromotor housing. In accordance with the present invention, the working air stream of the fan and the cooling air stream are thus separated and independent from each other. The cooling air can be drawn from outside according to invention, spread along the outside of the encapsulated electronics, and nevertheless also flow through the air gap of the motor between rotor and stator. 
   It is moreover provided according to invention, that motor electronics are arranged against direct contact with the cooling air stream, the motor electronics being chambered within a housing compartment bordered by a cooling attachment and the cooling air stream being conveyed past the housing compartment in such a manner that it flows over the outside surface of the cooling attachment, which outside surface is turned away from the motor electronics, whereas the inside surface of the cooling attachment is turned toward the motor electronics and demonstrates cooling surfaces standing in heat-conducting bearing contact with components of the motor electronics to be cooled. 
   According to invention the cooling air stream, which is initially generated for motor self-ventilation, is thus also used to cool the motor electronics. But here it is advantageous for the motor electronics to be accommodated chambered in such a manner, that direct contact with the cooling air stream is impossible. Rather, indirect cooling occurs according to invention, the flow occurring over the opposite side of the cooling attachment. The components dissipate the heat through the adjacent cooling surfaces of the cooling attachment. This arrangement according to invention prevents any pollutants and/or moisture, which could cause electrical problems, from reaching the vicinity of the motor electronics with the cooling air. Preferably the chambering of the motor electronics according to invention can even make it possible to dispense with encapsulating the electronics as a whole with an insulating potting compound. This will contribute to simple and economical manufacturability. 
   Other advantageous development characteristics and advantages of the invention are contained in the dependent claims and the following description. 
   The invention will be explained in more detail based on a preferred exemplary embodiment illustrated in the drawing. The drawing shows: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  an axial front view (view in the direction of the arrow I depicted in  FIG. 2 ) of an electromotor equipped with a cooling arrangement according to invention, 
       FIG. 2  an axial section in the plane II—II depicted in  FIG. 1 , 
       FIG. 3  another axial section, but in the plane III—III depicted in  FIG. 1 , 
       FIG. 4  a perspective exploded illustration of the basic components of the cooling arrangement according to invention in a first viewing direction (diagonally from the front), 
       FIG. 5  a perspective exploded illustration similar to  FIG. 4  in a second viewing direction (diagonally from the rear), 
       FIGS. 6 and 7  each a perspective view of the cooling attachment according to invention on its interior and exterior surface, respectively, 
       FIG. 8  a perspective view of the electromotor, 
       FIG. 9  an axial section of the electromotor, 
       FIG. 10  an external view of a blower in accordance with the invention, and 
       FIG. 11  an axial section through the fan in  FIG. 10 . 
   

   The same parts are always labeled with the same reference characters in the various figures of the drawing and each will therefore only be described once. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   As is first seen from  FIGS. 2 ,  3 ,  8 , and  9 , an electromotor  2  is preferably designed as an external rotor motor, a rotor  4  in the form of a bell-shaped or pot-shaped external rotor enclosing an interior stator  6 . On its closed side, the rotor  4  carries a cooling wheel  8  in the manner of a small radial or axial fan in order to generate a cooling air stream  10  streaming through or around a motor  2  for motor self-ventilation.  FIGS. 2 and 9  each indicate this cooling air stream  10  by dashed lines. For this, the front side of rotor  4 , which side supports the cooling wheel  8 , demonstrates axial flow holes  12  for the cooling air stream  10 . The cooling wheel  8  can advantageously be made from a disk, especially a disk made of a sheet material, wherein this disk may demonstrate free-punched and bent elements operating as blades. For this, see  FIG. 8  in particular. In a preferred embodiment, the rotor  4  is designed stepwise. Here a region of the rotor with a reduced diameter, the region that is assigned to the closed pot side and elongated over the rotor sheet stack, is offset radially inwards. This has the advantage on the one hand that the bearing span of the motor can be increased, which contributes to a substantial improvement in the durability of the motor&#39;s mounting, and on the other hand that the compact structural shape of the motor can be preserved. 
   As evident from  FIGS. 2 through 5 , motor electronics  14 , which are provided especially for electronic commutation control, are arranged chambered within a housing compartment  18  bordered by a cooling attachment  16  in such a manner that they (the motor electronics  14 ) are protected from direct contact with the cooling air stream  10 . The cooling air stream  10  nevertheless also cools the motor electronics  14  by being conveyed past the housing compartment  18  in such a manner that it flows over the outside surface  20  of the cooling attachment  16 , the outside surface being turned away from the motor electronics  14 . The opposite inside surface  22  of cooling attachment  16 , which inside surface is turned toward the motor electronics  14 , demonstrates cooling surfaces  24  by means of which the cooling attachment  16  stands in heat conducting bearing contact with components or regions of the motor electronics  14  that must be cooled. 
   As seen in  FIGS. 4 and 5 , the motor electronics  14  demonstrate a supporting plate  26 , which bears the components and extends perpendicular to the motor axis, and which can be made of a printed circuit board. The cooling attachment  16  demonstrates a bottom wall  28 , which is basically parallel to the supporting plate  26 . The arrangement is preferably in such a manner that the bottom wall  28  of cooling attachment  16  borders the housing compartment  18  on the side that is axially turned toward the electromotor  2 , and a separate lid component  30 , which is connected to the cooling attachment  16 , borders the other axial side of the housing compartment  18 , the side that faces way from the motor  2 , the housing compartment  18  accommodating the supporting plate  26 . This means that the outside surface  20  of cooling attachment  16  is turned toward the motor  2 , whereas the inside surface  22  faces away from motor  2 . On its inside surface  22 , which is turned away from the motor electronics  14 , the bottom wall  28  demonstrates a relief-like face structure, which is matched to the particular arrangement of components on supporting plate  26  to form the cooling surfaces  24 ; see  FIGS. 4 and 6  in particular. 
   In particular, the cooling attachment  16  together with the lid component  30  forms at least one preferred axial admission channel  32  leading past the housing compartment  18 , two admission channels  32  being located next to each other in the external peripheral region in the illustrated example. On the outside surface  20  of the cooling attachment  16 , which surface is turned toward the motor  2 , the or each admission channel  32  merges into a rear-flow chamber  34 . The bottom wall  28  of the cooling attachment  16  borders this rear-flow chamber  34  in the axial direction toward the housing compartment  18  and motor electronics  14  on one side, and an extra partitioning wall  36  borders this rear-flow chamber  34  in the axial direction toward the motor  2  on the other side (cf. the perspective drawings in  FIGS. 4 and 5 ). Here the centric vicinity of partitioning wall  36  demonstrates a transition hole  38  for the cooling air stream  10  flowing toward the motor  2 . In the preferred embodiment, the end of the rotor  4 , which is offset radially inwards, reaches through the transition hole  38 , an adequately wide annular gap serving the cooling air stream  10  being formed between the rotor  4  and transition hole  38 . 
   In this manner, the air drawn by the cooling wheel  8  first flows axially through the admission channels  32 , then flows along the outside surface  20  of cooling attachment  16  through the rear-flow chamber  34 , and then flows further through the transition hole  38  of the partitioning wall  36  over the cooling wheel  8  to the motor  2 . The air then flows axially through the air gap between stator  6  and rotor  4  and within a bypass to a first vicinity of the rotor, then flows around axially back to the rotor  4 , and is then radially carried off to the outside. The reader is referred to  FIG. 2  in particular. 
   As is furthermore evident from  FIGS. 5 and 7 , flow channels  40  are formed within the rear-flow chamber  34  in such a way that the cooling air stream  10  flows over the bottom wall  28  on the outside surface  20  of the cooling attachment  16  in a suitable manner. A largely uniform flow over the surface can thus be achieved. But it can be advantageous to provide for a locally reinforced flow over the surface of the cooling attachment to match the arrangement of the components and cooling surfaces  24 . In the illustrated, preferred embodiment, air guide ribs  42  on the outside surface  20  of the bottom wall  28  of the cooling attachment  16  form the flow channels  40 . But it is alternatively possible to also provide ribs on the partitioning wall  36 . In an advantageous embodiment of the invention, the flow channels  40  can be designed with a cross section that matches the volume flow of the cooling air stream  10  drawn by the cooling wheel  8  in such a manner that the flow in the vicinity of the flow channels  40  attains such a relatively high flow velocity that it prevents the deposit of air constituents, such as dirt particles and/or moisture. 
   In the preferred embodiment, the cooling attachment  16  demonstrates a basically cylindrically hollow peripheral wall  44 , designed as a single piece with the bottom wall  28 . One axial side of this peripheral wall  44  is preferably attached to the lid component  30  and, as seen in  FIGS. 2 and 3 , the other axial side is attached to an appropriate cylindrically hollow housing wall  46  of a motor supporting component  48 . The cooling attachment  16  with its peripheral wall  44 , the supporting component  48  with its housing wall  46 , and the lid component  30  thus practically form a common housing for the electromotor  2  and the cooling arrangement. At least one radial exhaust port  50  for the cooling attachment  10  is formed, especially in the vicinity of attachment between the peripheral wall  44  of the cooling attachment  16  and the housing wall  46  of the supporting component  48 .  FIGS. 6 and 8  deal with a preferred exemplary embodiment of five exhaust ports  50 , each partially formed by recesses of the supporting housing wall  46  and of the cooling attachment peripheral wall  44 , the recesses being open on the edge. 
   In accordance with  FIG. 2 , it is furthermore advantageous for the partitioning wall  36  to demonstrate an axially extended, basically cylindrically hollow ring land  52  that is located on the side that is axially facing away from the rear-flow chamber  34  and that encloses the rotor  4  with a small radial gap across a portion of the rotor&#39;s axial length in such a manner that the cooling air stream  10 , after it has flowed through or around the motor  2 , will be radially guided away from the rotor  4  through the ring land  52  and outwardly toward the exhaust ports  50 . The ring land  52  is also easy to recognize in  FIG. 5 . 
   As furthermore evident from  FIG. 4 , the motor electronics  14  demonstrates at least one plug-and-socket connector component  54  for connecting an external motor connecting cable (not illustrated) for the external motor connection. The lid component  30  possesses a connection opening  56  in the vicinity of the plug-and-socket connector component  54 . The reader is referred to the front view in  FIG. 1  for this. 
   Connector elements  58  (see  FIG. 2 ), which are arranged in a holding recess  60  that is designed as a single piece with the partitioning wall  36 , are appropriately provided for internally connecting the motor electronics  14  to the motor windings (cf.  FIGS. 4 and 5 ). In accordance with  FIG. 7 , the bottom wall  28  of the cooling attachment  16  demonstrates a connecting hole  62  in the vicinity of the holding recess  60 . In accordance with  FIG. 2 , a reciprocal connector element  64 , which advantageously plugs together with the connector element  58 , is arranged within the motor  2  (also see  FIG. 8 ). 
   As depicted in  FIG. 2 , it is furthermore expedient for sealing means  66  to connect the bottom wall  28  of the cooling attachment  16  and the partitioning wall  36  in the region enclosing the holding recess  60  and the connecting hole  62 , especially sealing means  66  similar to a labyrinth box with webs that mutually engage each other axially. This will prevent admission of cooling air into the housing compartment  18  in this region too. 
   As finally can still be seen from  FIGS. 2 and 3  and from  FIG. 9 , the electromotor  2 , together with a sheet stack of its stator  6 , is seated on a bearing stay pipe  68  which, on the side that isn&#39;t enclosed by the rotor  4 , is preferably connected as a single piece to a flange-like wall section  70  of supporting component  48  that extends perpendicular to the motor axis. A rotor shaft  72  is rotatably mounted within the bearing stay pipe  68  by means of bearing elements, the rotor shaft  72  projecting axially from the wall section and being attachable to practically any desired aggregate to be driven, such as a pump. 
   The supporting component  48  together with its components (housing wall  46 , wall section  70 , and preferably a bearing stay pipe  68  too) is designed as a single-pieced structural part, especially of metal or else plastic. The cooling attachment  16  consists of a material that conducts heat well, especially aluminum. The lid component  30  and the partitioning wall  36  can actually consist of any material, but especially plastic. 
     FIG. 10  illustrates a blower  80  according to invention. This blower is particularly suitable as a high-pressure blower. As illustrated in  FIG. 11 , it features a fan arrangement  81 , comprising of a fan  82  and a fan housing  83 . The fan  82  comprises of at least one fan impeller. However, several fan impellors can also be arranged behind each other. It is also possible to provide a stationary fan impeller between each of the individual fan impellors. The housing  83  demonstrates an aspirating hole  85  in the centerline X—X of the blower  80  in a front wall  84  of the housing  83 . The fan arrangement  81  moreover possesses a fan shaft  86  upon which one or several fan impellors  82  are fastened. In the illustrated exemplary embodiment, the fan shaft  86  is designed as a single piece with the rotor shaft  72 . The fan housing  83  is attached to the housing wall  46  since the housing encloses an annular collar of the housing wall  46  and is slid onto and fastened to this collar. The gap between the annular collar and the fan housing  83  is sealed. When the blower according to invention is in operation, working air is drawn in axially through the aspirating hole  85 , and blown-off tangentially to the housing through a blower aperture  87  within the housing wall  46  by means of a molded connection piece  88 . The wall section  70  of the supporting component  48  extends perpendicularly to the motor axis and forms a separation between the interior space for accommodating the electromotor  2  and the working air space of the fan arrangement  81 , so that the working air flowing within the fan housing  83  is completely separated from the cooling air flowing inside the interior space of the electromotor  2 . For this, it is provided that the passage of the motor shaft  72  through the wall section  70  is sealed airtight, so that the wall section  70  closes off one side of the interior space that the working air flows through. 
   As far of the rest of the design of electromotor  2  and the design of the cooling of the motor electronics  14  is concerned, let us refer to the embodiments represented by  FIGS. 1 through 9  so that these details don&#39;t have to be repeated again in relation to  FIGS. 10 and 11 . 
   The invention is not limited to the exemplary embodiments that are illustrated and described, but includes all embodiments that work in the manner of the spirit of the invention. Furthermore, the invention is also not yet restricted to the combination of characteristics defined in Claim  1 , but can also be defined by any other desired combination of particular characteristics of all disclosed individual characteristics as a whole. This means that practically any single characteristic of claim  1  can be omitted or replaced by at least one individual characteristic disclosed at another place in the application. To this extent, claim  1  must be understood merely as a first attempt at a formulation for an invention.