Abstract:
In a method of mounting attachment parts to an electric machine, a rotor of the electric machine is non-rotatably supported in a bearing device. A stator of the electric machine is detachably secured in a predefined first installation position by a clamping device, and a first attachment part is mounted to the stator. The clamping device is then released, and the electric machine is operated as motor for a time period sufficient for the stator to rotate in relation to the rotor until reaching a second installation position. The stator is secured by the clamping device in the second installation position, and a second attachment part is mounted to the stator.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of German Patent Application, Ser. No. 20 2015 014 942.3, filed Nov. 18, 2015, pursuant to 35 U.S.C. 119(a)-(d), the disclosure) of which is incorporated herein by reference in its entirety as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a method of mounting attachment parts to an electric machine. 
         [0003]    The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention. 
         [0004]    Electric machines typically include a stator and a rotor which rotates in relation to the stator. Electric machines can be operated as motor or as generator or selectively as motor and generator. Once stator, rotor, bearings, and housing parts of such electric machines have been assembled, various attachment parts, such as cooling systems, power electronics, and wiring, need to be installed. For reasons of ergonomics, efforts are underway to position the electric machine in such a way as to facilitate the installation of such attachment parts. One approach involves the use of turntables by which workpiece holders for example can be pivoted. The use of separate turntables is, however, cumbersome, inefficient, and cost-intensive. 
         [0005]    It would therefore be desirable and advantageous to provide an improved method of mounting attachment parts to an electric machine to obviate prior art shortcomings. 
       SUMMARY OF THE INVENTION 
       [0006]    According to one aspect of the present invention, a method of mounting attachment parts to an electric machine includes non-rotatably supporting a rotor of the electric machine in a bearing device, detachably securing a stator of the electric machine in a predefined first installation position by a clamping device, mounting a first attachment part to the stator, releasing the clamping device, operating the electric machine as motor for a time period sufficient for the stator to rotate in relation to the rotor until reaching a second installation position, securing the stator by the clamping device in the second installation position, and mounting a second attachment part to the stator. 
         [0007]    The present invention resolves prior art problems by being able to set any position of the stator as its installation position in relation to the rotor so that the electric machine can be positioned in such a way that the connection direction of the attachment part is realized in the direction of its force of gravity or weight force, i.e. the attachment part can be mounted from above. This can be realized by correspondingly adjusting the time period of applying current to energize the electric machine so that the electric machine can be placed in any appropriate position. The rotor of the electric machine is hereby restrained against rotation by non-rotatably supporting the rotor of the electric machine, e.g. via the rotor shaft, and allowing the stator, when energized, i.e. when current is applied to stator windings of the stator, to rotate in relation to the rotor. When the stator has reached the desired installation position, the current feed to the stator windings is stopped to thereby fix the stator in place. The attachment part can now be mounted in this fixed installation position of the stator. There is thus no need to provide any separate turntable or other turning device to effect a pivoting of the electric machine to a wanted installation position. 
         [0008]    According to another advantageous feature of the present invention, a function test to check operativeness of the electric machine can be executed, while the stator rotates about the rotor from the first installation position to the second installation position during operation of the electric machine. In this way, while the stator is energized to rotate to a further installation position, a final installation control is carried out by checking the function of the electric machine. In such a final installation control, the operativeness of a rotary drive, rotation direction, sensor assembly, etc. can be checked. 
         [0009]    According to another advantageous feature of the present invention, a position of the stator can be detected by position sensors of the electric machine. Using machine-own sensors eliminates the need for use of external sensors for detection of the stator position. Of course, the stator position may also be monitored by sensors located outside of the electric machine. 
         [0010]    According to another advantageous feature of the present invention, the stator can be secured by clamping a stator housing of the stator via the clamping device. 
         [0011]    According to another advantageous feature of the present invention, a three-phase winding of the stator can be energized to operate the electric machine as motor. Using such a three-phase winding enables a three-phase rotating field to be generated with low frequency. 
         [0012]    According to another advantageous feature of the present invention, the electric machine can be constructed as polyphase machine, e.g. as synchronous machine or asynchronous machine. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0013]    Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which: 
           [0014]      FIG. 1  is a schematic illustration of an electric machine in the form of a rotary field machine on an installation device in a predefined first installation position; 
           [0015]      FIG. 2  is a schematic illustration of the rotary field machine of  FIG. 1 , depicting installation of a first attachment part onto the rotary field machine in the predefined first installation position; 
           [0016]      FIG. 3  is a schematic illustration of the rotary field machine of  FIG. 1  in a second installation position; 
           [0017]      FIG. 4  is a schematic illustration of the rotary field machine of  FIG. 3 , depicting installation of a second attachment part onto the rotary field machine in the second installation position; and 
           [0018]      FIG. 5  is a block diagram showing a relationship between components involved in a method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0019]    Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments may be illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. 
         [0020]    Turning now to the drawing, and in particular to  FIG. 1 , there is shown a schematic illustration of an electric machine, generally designated by reference numeral  1 , mounted onto an installation device, generally designated by reference numeral  10 . The electric machine  1  is represented here, by way of example, as a rotary field machine which can be constructed as synchronous machine or asynchronous machine. The electric machine  1  includes a rotor  1 . 1 , mounted on a rotor shaft  1 . 10 , and a stator  1 . 2 , arranged in a stator housing  1 . 20 . The stator  1 . 2  includes a stator winding  1 . 21 , configured as rotating field winding or three-phase winding so as to generate a three-phase rotating field. 
         [0021]    The electric machine  1  is mounted onto the installation device  10  by non-rotatably connecting the rotor shaft  1 . 10  of the rotor  1 . 1  with a bearing device  10 . 2  of the installation device  10 . As a result, the rotor  1 . 1  is prevented from rotating in relation to the stator  10 . 2 , when a three-phase current is applied to the stator winding  1 . 21 . Rather, the stator  1 . 2  is caused to rotate in relation to the rotor  1 . 1 . To fix the stator  1 . 2  in a predefined installation position Ml, the installation device  10  includes a clamping device  10 . 2 , which has jaws to clamp the stator housing  1 . 20  in the predefined installation position M 1  so as to prevent the stator  1 . 2  from rotating away from the predefined installation position M 1 . The jaws of the clamping device  10 . 2  can be pivoted about their pivot axes, as indicated by the arrows, between a clamping position I, in which the stator housing  1 . 20  is firmly clamped, as indicated shown in  FIG. 1 , and a release position II, in which the stator housing  1 . 20  is liberated, as indicated in  FIG. 2 . 
         [0022]    In the installation position M 1  of the stator  1 . 2 , as shown in  FIG. 1 , an installer is able to place an attachment part  2  from above, i.e. in z direction, as indicated in  FIG. 1 , upon a mounting surface  1 . 22  of the stator housing  1 . 20 . The connection direction, as indicated by arrow F, thus corresponds to the force of gravity or weight force of the attachment part  2 . During installation, the stator housing  1 . 20  remains in the installation position M 1  once the stator housing  1 . 20  is held by the clamping device  10 . 2  in the clamping position I. 
         [0023]    Once the attachment part  2  has been mounted to the stator housing  1 . 20 , the clamping device  10 . 2  is released, i.e. pivoted from clamping position I to the release position II, as shown in  FIG. 2 . At the same time, the stator winding  1 . 21  is energized with a three-phase current to cause the stator  1 . 2  to rotate in a rotation direction D about the rotor  1 . 1 . For this purpose, a three-phase alternating current with low frequency of, for example, 0.5 Hz is used to realize a slow rotation speed of the stator  1 . 2  together with the stator housing  1 . 20  about the rotor  1 . 1 . 
         [0024]    Current feed to the stator winding  1 . 21  is stopped, when the stator  1 . 2  has reached a further installation position M 2  which is rotated, for example, by 90° in relation to the predefined installation position M 1 . This is shown in  FIG. 3 . Also in this further installation position M 2 , the installer can mount a further attachment part  3  onto a further mounting surface  1 . 23  from above, i.e. again in z direction. The connection direction F again corresponds to the force of gravity or weight force now of the attachment part  3 . 
         [0025]    When the stator  1 . 2  has reached the further installation position M 2 , the clamping device  10 . 2  is pivoted into the clamping position I, as shown in  FIG. 4 . As a result, the stator housing  1 . 20  is securely clamped in the further installation position M 2 , and the installer is now able to mount the further attachment part  3  to the stator housing  1 . 20 .  FIG. 4  shows the electric machine  1  with the installed attachment part  3 . 
         [0026]    The position that is assumed by the stator  1 . 2  as the stator winding  1 . 21  is energized, is monitored by sensors ( FIG. 5 ) of the electric machine  1  so that the current feed to the stator winding  1 . 21  can be stopped at the exact right time. As an alternative, the use of external sensors which can be arranged on the installation device  10 , is also conceivable for detecting the position of the stator  1 . 2 . 
         [0027]    As the electric machine  1  is operated so as to cause a rotation of the stator  1 . 2  about the rotor  1 . 1  from the predefined installation position M 1  to the further installation position M 2 , the electric machine  1  undergoes a function test in which the operativeness of the electric machine  1  is checked, as shown in  FIG. 5 . Thus, the stator  1 . 2  is energized for rotation to the further installation position M 2  while at the same time the operativeness of the electric machine  1  is checked to execute a final installation control, in which the rotary drive, rotation direction, sensor assembly, electrical and mechanical parameter etc. of the electric machine are checked. 
         [0028]    Further attachment parts can be mounted by repeating the steps of opening the clamping device  10 . 2 , rotating the stator  1 . 2  together with the stator housing  1 . 20  to a further installation position, and subsequent clamping of the stator  1 . 2  in the further installation position, as needed. 
         [0029]    While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. 
         [0030]    What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: