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Rotor assembly for electric motor Disclosure Number: IPCOM000236861D
Publication Date: 2014-May-20

Publishing Venue

The Prior Art Database

Related People

Jere Kolehmainen: INVENTOR [+2]


An electric motor rotor assembly, comprising a rotor (660), and an end plate (610A, 610B) arranged at an end of the rotor (660), and a stud bolt (630A, 630B) arranged through the rotor (660) and the end plate (610A, 610B), wherein the end plate (610A, 610B) comprises a through hole for receiving the stud bolt (630A). The through hole of the end plate (610A) comprises a conical section on an opposite side of the end plate (610A) than the side of the end plate (610A) that faces the rotor (660).

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       The present invention relates to a rotor assembly for an electric mo- tor.


          Electric motors typically comprise a rotor formed of a stack of elec- tric sheets and a shaft arranged through the stack of sheets. The rotor is ar- ranged to rotate with respect to a stator residing interior of exterior of the rotor. Typically the stack of sheets has end plates at both ends for protecting the sheet stack and for balancing the rotor assembly. The end plate also assists in 10

the rotary cutting phase of the rotor.

       Typically, the end plate is heat fitted to the shaft. The end plate may then be used in balancing of the assembly by welding extra pieces to the end plate, for instance.

Heat fitting and machining of the end plate afterwards are laborious

processes, and an improved solution for fastening and balancing the rotor as- sembly is thus called for.


       An object of the present invention is thus to provide an apparatus so as to alleviate the above disadvantages.

       The objects of the invention are achieved by what is stated in the independent claim. Some preferred embodiments of the invention are dis- closed in the dependent claims.

          By help of the invention a simple structure is obtained. Furthermore, no machining, welding or drilling is needed in the balancing process afterwards 25

when the assembly has been done.


       In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which

Figure 1 shows an embodiment of an end plate;

Figure 2 shows an embodiment of a rotor sheet;

Figure 3 shows an end plate having a rotor sheet behind;





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       Figure 4 shows an overlap of the end plate of Figure 1 and rotor sheet of Figure 2 with stud bolts and balancing members mounted;

Figure 5 shows a perspective drawing of an end plate;

Figure 6 shows a cross-section of the rotor assembly from side; and Figure 7 shows a cross-section of end plate.


       The embodiments relate to electric machines or motors. In an em- bodiment the electric motor is a synchronous reluctance motor but the inven- tion can be applied to other types of electric motors also.

The embodiments relate to electric motor structures having a rotor

formed of a stack or rotor sheets. At each end of the stack of rotor sheets there is provided an end plate. A shaft is arranged such that it penetrates the stack of rotor sheets and the end plates.

          Figure 1 shows one embodiment of the end plate 110. The end plate may have an outer perimeter of a circle, and have a central circular shaft 15

hole for receiving a shaft of the motor. The shown end plate has a plurality of cooling openings 114A, 114B and 114C for conveying cooling air in to and/or out from the rotor. The cooling openings may take different shapes as shown.

       Figure 1 shows also two other types of openings/threads 116A, 116B and 118A, 118B.

          The openings...