Abstract:
The present invention relates to a fan, to a method, and to a device for assembling the fan. The fan has an axis of rotation, which is connected to a dog, wherein the dog is connected to a fan wheel, wherein the dog, in a first number of contact surfaces, is in contact with additional contact surfaces of the fan wheel, wherein the dog and/or the fan wheel have more than the first number of contact surfaces and/or additional contact surfaces, wherein at least two contact surfaces have different height positions with respect to a central axis of the dog and/or the fan wheel.

Description:
BACKGROUND OF THE INVENTION 
     The invention refers to a fan with a driving dog and a fan wheel, to a method for assembling the fan wheel, and to a device for implementing the method. 
     A fan with a fan mounting with a dynamic unbalance weight is known from international patent application WO03/040570 A1. The described axial fan has a hub region for connecting the axial fan to a drive shaft of an electric drive, wherein the axial fan is statically balanced by means of a balance weight. A flexible connection is formed in the hub region between the axial fan and the drive shaft of an electric drive. 
     The occurrence of unbalance in a fan constitutes a problem particularly in the case of high-speed fans. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a fan, a method for assembling a fan, and a device for implementing the method, wherein a reduction of the unbalance of the fan can be achieved. 
     One advantage of the fan is that the driving dog and/or the fan wheel has or have a plurality of contact surfaces, wherein the contact surfaces have different height positions with regard to a center axis of the driving dog or of the fan wheel, and wherein the driving dog butts against the fan wheel by a fixed number of contact surfaces so that the unbalance, especially the dynamic unbalance, is reduced. Therefore, a two-plane unbalance can be reduced. 
     The method according to the invention for assembling the fan wheel with the driving dog has the advantage that an optimized height position between driving dog and fan wheel is created by means of a plurality of contact surfaces which have different height positions with regard to a center plane of the driving dog and/or to a center plane of the fan wheel. For this, different positions, i.e. different pairings of contact surfaces between driving dog and fan wheel are set, a level for the unbalance is measured, and the driving dog is fixedly connected to the fan wheel in the position in which the lowest unbalance occurs. Therefore, by means of the provided contact surfaces at different heights, an inclined position of the fan wheel with regard to a rotational axis or an unbalance, particularly a dynamic unbalance, of the fan wheel can be reduced. 
     The device according to the invention has the advantage that provision is made for a fixing bolt which fixes the fan wheel and the driving dog symmetrically in relation to each other, that provision is made for pressing-on means with which the fan can be pressed onto the driving dog in different angular positions. In this way, the method for determining an optimized angular position can be implemented without a screw fastening of the driving dog to the fan wheel being necessary. 
     Depending upon the selected embodiment, at least two contact surfaces of the driving dog have different height positions with regard to a center plane of the driving dog, wherein the contact surfaces of the fan wheel are arranged in one height position with regard to a center plane of the fan wheel. 
     In a further embodiment, the contact surfaces of the fan wheel are arranged in at least two different height positions with regard to a center plane of the fan wheel, wherein the contact surfaces of the driving dog are arranged at one height position with regard to the center axis of the driving dog. 
     Depending upon the selected embodiment, both the contact surfaces of the fan wheel and the contact surfaces of the driving dog can be arranged at at least two different height positions with regard to the corresponding center planes. 
     In a further embodiment, the driving dog and/or the fan wheel has or have groups of contact surfaces, wherein the groups have fixed angular spacings with regard to a center of the fan wheel. Each group has a plurality of contact surfaces, wherein the contact surfaces of a group are arranged in a row with fixed angular spacings. The contact surfaces of a group are arranged at a fixed radial distance from the middle of the fan wheel. In this way, provision is made for a large number of systematically arranged contact surfaces which allow a simple and quick selection of the contact angle between the fan wheel and the driving dog. 
     In a further embodiment, the contact surfaces of a group are arranged at at least two different height positions with regard to the center plane of the driving dog or the center plane of the fan wheel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic view of a fan, 
         FIG. 2  shows a cross section through a part of the driving dog and of the fan wheel, 
         FIG. 3  shows a plan view of a driving dog, 
         FIG. 4  shows a section F 1  through a driving dog, 
         FIG. 5  shows a section F 2  through the driving dog, 
         FIG. 6  shows a plan view of a fan wheel, 
         FIG. 7  shows a schematic view of the driving dog and of the fan wheel in a first angular position, 
         FIG. 8  shows a schematic view in a second angular position, 
         FIG. 9  shows a schematic view in a third angular position, 
         FIG. 10  schematically shows a finishing device for assembling the fan wheel on the driving dog, 
         FIG. 11  shows a partial cross section through the finishing device. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows in a schematic view a fan  1  with a drive  2  which has a drive shaft  3 . The drive shaft  3  is connected to a driving dog  4  in the form of a disk. The driving dog  4  may also be of a three-legged design or have any other form. The driving dog  4  is connected to the drive shaft  3  in a rotation-resistant manner at least in one rotational direction. A fan wheel  5  is fastened on a front side of the driving dog  4 . For example, the driving dog  4  has a central opening through which the drive shaft  3  is guided. The driving dog  4  can be connected to the drive shaft  3  via a press fit. Moreover, the fan wheel  5  can also have a central opening  20  into which the drive shaft  3  protrudes. In this way, both the driving dog  4  and the fan wheel  5  are aligned axially on a rotational axis which corresponds to the drive shaft. 
     Depending upon the selected embodiment, however, only the driving dog  4  may be connected directly to the drive shaft  3 . For fastening the fan wheel  5  on the driving dog  4 , provision is made for fastening means  6 , for example in the form of screws. Other types of fastening means, however, such as adhesive means, can also be used in order to connect the fan wheel  5  to the driving dog  4 . 
     The fan wheel  5  has a fan hub  6 , on the outer side of which fan vanes  7  are formed. 
     For avoiding unbalance, it is necessary for the fan wheel  5  to be fastened on the driving dog  4  in a plane perpendicular to the longitudinal axis of the drive shaft  3 . For this, the driving dog  4  and the fan wheel  5  have defined contact surfaces. 
     In a further embodiment, the fan wheel  5  is fastened for example by a driving dog  4  on a rotor of a brushless external-rotor motor. In this case, the fan wheel  5  can also be fastened directly on the rotor. 
       FIG. 2  shows in a schematic view a cross section through the drive shaft  3 , the driving dog  4  and the fan wheel  5  in the region of a contact region. A contact block  8  is formed on an outer side of the driving dog  4 . An additional contact block  9 , which is part of the fan wheel  5 , bears on the contact block  8 . The contact block  8  has a first contact surface  10  which bears on an additional contact surface  11  of the additional contact block  9 . The contact surface  10 , as seen in the axial direction of the drive shaft  3 , is arranged at a first height h 1  with regard to a center plane  12  of the driving dog  4 . The additional contact surface  11  of the additional contact block  9  is arranged at a further height position h 2  with regard to a second center plane  13  of the fan wheel  5 . The center planes are arranged perpendicularly to the drive shaft  3 . 
     For a reliable alignment, provision is made for three contact regions with a defined contact surface  10  of the driving dog  4  in each case and an associated defined additional contact surface  11  of the fan wheel  5 . The three contact regions are spaced apart in this case preferably by an angle of 120° and lie on a circular line with regard to a center of the driving dog or of the fan wheel. Depending upon the selected embodiment, provision may also be made for more than three contact regions. Moreover, instead of a contact block  8 , provision may also be made for an opening with a contact surface. In a further embodiment, instead of the additional contact block  9  an additional opening may also be formed in the fan wheel  5 , in which an additional contact surface  11  is formed. 
       FIG. 3  shows a schematic view of an outer side of the driving dog  4  which is associated with the fan hub  6  in the assembled state. On the front side  14 , the driving dog  4  has three groups  15 ,  16 ,  17  of contact surfaces  10 . In the depicted exemplary embodiment, each group has four contact surfaces  10 . The contact surfaces  10  of the groups  15 ,  16 ,  17  are arranged on a circular ring with constant radius to the middle  21  of the driving dog. Moreover, the contact surfaces of a group have the same angular distance from each other in each case. Furthermore, the first, second, third and fourth contact surface of a group in each case, as seen in the counterclockwise direction, are arranged at a 120° angle to the first, second, third and fourth contact surface in each case, 
     In the depicted exemplary embodiment, the first contact surface in each case has a height position z 0  with regard to the surface of the outer side of the driving dog  4 . In the first group  15 , the second, third and fourth contact surface B 1 , B 2 , B 3 , following in the clockwise direction, have a height position zn according to the following formula: Bn: =zn=z 0 +n×a, wherein n can be a number from 1 to 10 and the parameter a can have a value of between 0.01 and 0.1 mm. Instead of the value range of 0.01 mm and 0.1 mm, the parameter a can also lie within a range of between 0.01 and 1 mm. The contact surfaces are identified by n in the sequence in the counterclockwise direction. The contact surface B 1  has the height position z 1 =z 0 +1×a=z 0 +a. 
     In the second group  16 , the second, third and fourth contact surface C 1 , C 2 , C 3  have the following height position zn with regard to the surface of the outer side of the driving dog  4 : Cn=zn=z 0 −(n×a). In the same way, the second, third and fourth contact surface C 1 , C 2 , C 3 , as seen in the counterclockwise direction, of the third group  17  have a height position which is determined by means of the index n and the following formula: Cn has the height position zn=z 0 (n×a) in relation to the surface of the outer side of the driving dog  4 . 
     The contact surface C 1  therefore has the height position z 1 =z 0 (1×a)=z 0 −a. This means that the height positions of the contact surfaces of the first group  15  increase in steps in the counterclockwise direction. The height positions of the contact surfaces of the second and third groups  16 ,  17  decrease in steps in the counterclockwise direction. Depending upon the selected embodiment, the contact surfaces of the second and third groups  16 ,  17  also have different height positions. In particular, the second or third group  16 ,  17  can also have contact surfaces with height positions corresponding to those of the first group  15 . 
       FIG. 4  shows a section F 1  through a contact surface A which is arranged on a contact block  8  at a height position z 0  with regard to the surface of the driving dog  4 . 
       FIG. 5  shows a cross section through a contact surface C 1  which is arranged on a contact block  8  at a height position z 1 =z 0 (1×a)=z 0 −a with regard to the surface of the driving dog  4 . 
       FIG. 6  shows a schematic view of the fan wheel  5  with six additional contact surfaces  11 , wherein only the fan hub  6  is shown. Depending upon the selected embodiment, provision can also be made for only three additional contact surfaces  11  or multiples of three additional contact surfaces  11 , wherein three additional contact surfaces  11  have an angular spacing of 120° in each case. In addition to the depicted exemplary embodiment, the six additional contact surfaces  11  of the fan wheel  5  in each case have an angular spacing of 60° from each other. The additional contact surfaces  11  may be formed on additional contact blocks  9  or in openings of the fan wheel  5 . The depth of the openings in this case, however, must be less than the height of the lowest contact block  8  of the driving dog  4 . 
     In the view of the driving dog  4  of  FIG. 3 , the three first contact surfaces  10  represent a first bearing position, the second contact surfaces B 1 , C 1 , C 1  of the first, second and third groups  15 ,  16 ,  17  in each case represent a second bearing position, the third contact surfaces B 2 , C 2 , C 2  in each case of the first, second and third groups  15 ,  16 ,  17  represent a third bearing position and the fourth contact surfaces B 3 , C 3 , C 3  in each case of the first, second and third groups  15 ,  16 ,  17  in each case represent a fourth bearing position by which the driving dog  4  can be brought to bear on the corresponding additional contact surfaces  11  of the fan wheel  5 . 
     Since in the selected exemplary embodiment the additional contact surfaces  11  are arranged at a standard height position and the contact surfaces of the first group  15  of the driving dog  4  increase in height position in the counterclockwise direction, wherein the contact surfaces of the second and third groups  16  and  17  decrease in height position in the counterclockwise direction, different inclined positions can be set regardless of whether which contact surface of the first, second and third groups  15 ,  16 ,  17  are used for bearing on the fan wheel  5 . 
       FIG. 7  shows a schematic view of an assembled fan, in which only the driving dog  4  and the fan hub  6  of the fan wheel  5  are shown. In  FIG. 7 , the fan wheel  5  is fastened on the driving dog  4  in a first angular position, wherein the fan wheel  5  has three additional contact surfaces  11  which bear on the three first contact surfaces A of the groups  15 ,  16 ,  17  of the driving dog  4 . In this position, the fan wheel  5  is aligned parallel to the driving dog  4  since the additional contact surfaces  11  of the fan wheel  5  have the same height position with regard to a center plane of the fan wheel  5  and, moreover, the first contact surfaces A of the groups  15 ,  16 ,  17  of the driving dog  4  also have the same height position with regard to the center plane of the driving dog  4 . 
       FIG. 8  shows a driving dog  4  and a fan wheel  5  of a fan  1 , wherein the fan wheel  5  bears on the driving dog  4  in a second position and is fastened to the driving dog. In the second position, the three additional contact surfaces  11  of the fan wheel  5  are arranged on the second contact surfaces  10 , B 1 , C 1 , C 1  in each case, as seen in the counterclockwise direction, of the first, second and third groups  15 ,  16 ,  17  of the driving dog  4 . The height position of the second contact surface B 1  of the first group  15  of the driving dog  4  has the following height position: z 0 +1×a=0+a. The height position of the second contact surface C 1  of the second group  16  of the driving dog  4  has the height position z 0 (1×a)=z 0  a. Similarly, the second contact surface of the third group  16  of the driving dog  4  has the height position z 0 −(1×a)=z 0  a. 
     Therefore, a calculated inclined position between the driving dog  4  and the fan wheel  5  is set. 
       FIG. 9  shows a schematic view of a fan wheel  5  and of a driving dog  4  of the fan  1  in a third angular position. In the third angular position, the additional contact surfaces  11  of the fan wheel  5  bear on the fourth contact surfaces B 3 , C 3 , C 3  in each case, as seen in the counterclockwise direction, of the first, second and third groups  15 ,  16 ,  17  of the driving dog  4 . In this third position, the fan wheel  5  is arranged in a manner in which it is tilted to an even greater degree in relation to the driving dog  4  than in the second position. This ensues because the height position of the fourth contact surface B 3  of the first group  15  has the following height position: z 0 +(3×a)=z 0 +3a. Moreover, the fourth contact surfaces of the second and third groups  16 ,  17  of the driving dog  4  have the following height position: z 0 −(3×a)=z 0 −3a. Therefore, the distance between the fan wheel  5  and the driving dog  4  in the region of the contact surfaces of the second and third groups is less by the distance  6   a  than in the region of the fourth contact surface of the first group  15 . 
     Therefore, by means of the depicted embodiments four angular positions which are inclined to a different degree can be created when assembling the driving dog with the fan wheel  5 . A further variation, moreover, can be achieved by provision being made for not only three additional contact surfaces  11  on the fan wheel  5  but, for example, for six additional contact surfaces, as is shown in  FIG. 6 . Therefore, not only three additional contact surfaces  11  but six additional contact surfaces  11  are made available in order to set an optimum angular position between the fan wheel  5  and the driving dog  4  in which a preferred, preferably minimal unbalance exists. 
     The optimum angular position between the driving dog  4  and the fan wheel  5  is determined by all possible angular positions being tested and a resulting unbalance being measured. Final fastening of the fan wheel  5  on the driving dog  4  is then undertaken in the angular position in which the lowest unbalance is encountered. In this way, by means of a plurality of groups of contact surfaces with different height positions a calculated inclined position between the fan wheel  5  and the driving dog  4  can be set, with which an existing unbalance is compensated. 
     In the depicted exemplary embodiment, the groups of contact surfaces  10 , arranged at different heights, are arranged on the driving dog  4 . Depending upon the selected embodiment, the same groups of contact surfaces  10  with different height positions can also be formed on the fan wheel  5 . In this way, the possibility of the combination of angular positions is additionally increased. Moreover, instead of the depicted exemplary embodiment, the groups of additional contact surfaces  10 , arranged at different heights, can be arranged on the fan wheel  5  and the driving dog  4  can have contact surfaces  10  with the same height position, as is shown in the example of the fan wheel  5  of  FIG. 4 . 
       FIG. 10  shows an arrangement for testing and for assembling a driving dog  4  with a fan wheel  5 . Thus, the arrangement has a baseplate with a centering bolt  23  which is guided through the center opening of the driving dog  4  and the center opening of the fan wheel  5 . By means of three hydraulically operable fixing bolts  24 , the fan wheel  5  is then pressed against the driving dog  4 , wherein the fan wheel  5  bears by additional contact surfaces  11  on contact surfaces  10  of the driving dog  4  in a first angular position. Then, for example an axial eccentricity measurement is carried out in order to determine by means of a measuring system  28  the unbalance on the fixed angular position. For this, the arrangement with the fan wheel  5  is set in rotation and by means of the measuring system  28  the unbalance of the arrangement consisting of driving dog and fan wheel is determined by an axial eccentricity measurement. In a further angular position, the fan wheel  5  is then pressed against the driving dog  4  by means of the fixing bolt and an unbalance measured once again. In this way, the angular position in which the lowest unbalance occurs is determined. In this angular position, the fan wheel  5  is then fixedly connected to the driving dog  4 , especially screw-fastened. For this, for example auto screw connections  25  are used. 
     The fixing bolt  24  may be operated by means of a hydraulic cylinder, for example. 
       FIG. 11  shows a cross section through a corresponding arrangement of a baseplate  29  with a centering bolt  23  and with fixing bolts  24  with hydraulic cylinders  26 , with which a friction-resistant connection can be achieved between the driving dog  4  and the fan wheel  5  for measuring the unbalance.