Abstract:
A rotor according to the prior art has a top part and a bottom part, where the bottom part has stays that are mechanically connected to the top part. However, this has the disadvantage that very strict tolerances must be respected and the type of fastening is not secure. A rotor according to the invention has a ring, which presses stays and thus, by means of positive and frictional engagement, magnets against a tubular element, which in turn is disposed on a bottom part. The bottom part, together with a rotor shaft and a top part, constitutes a rotor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a 35 U.S.C. 371 application of PCT/DE 01/01269, filed on Mar. 30, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is based on a rotor including a magnet holder having top and bottom parts joined by stays. 
     2. Description of the Prior Art 
     A rotor with a magnet holder is already known from U.S. Pat. No. 4,591,749. The magnet securing apparatus is comprised of a top part, a bottom part, and stays. The top part and bottom part are connected to each other through mechanical deformation of the stays. This type of connection, however, is not very operationally reliable and very strict tolerances must be maintained for the assembly of the rotor. 
     SUMMARY OF THE INVENTION 
     The rotor according to the invention has the advantage over the prior art that a rotor is assembled in a simple manner. 
     In order achieve an advantageous securing of magnets to the rotor by means of stays, it is useful for the stays to constitute a positive engagement with the magnets because as a result, forces during operation of the rotor are distributed over a greater area. 
     It is advantageous for each stay to have an axial tab that is engaged by a ring because this allows the ring to not protrude past a circumferential surface of the stay and magnet. 
     It is advantageous to embody a top part of the rotor as disk-shaped because this makes the top part easy to produce. 
     It is also advantageous to fasten a bottom part to a rotor shaft. 
     It is particularly advantageous that the stays and magnets rest against a tubular element because then the ring presses the stays and magnets against the tubular element. 
     To secure the stays to the tubular element, it is advantageous for at least one of the stays to have a pin, which engages in a recess in the surface of the tubular element. 
     The assembly of the tubular element and bottom part can take place in an advantageous manner because the tubular element has a radial collar, which is oriented toward the central axis and can be inserted into a corresponding groove on the bottom part. As a result, the tubular element is also secured to the bottom. 
     In order to compensate for a tolerance between the tubular element and the bottom part, it is advantageous for the bottom part to have a radially protruding spring rib. 
     The bottom part and top part can easily be held together by a detent connection. 
     In order to reduce the number of parts to be assembled, it is advantageous to embody the stays as being of one piece with the bottom part or a top part. 
     If the tubular element is a tubular ring, the number of parts to be assembled is advantageously reduced and the assembly is simplified. 
     In order to compensate for an imbalance of the rotor, it is advantageous for the bottom part to have bores into which balancing weights can be inserted. 
     If a ring is embodied as a spring ring, the stays can be advantageously pressed against the tubular element and the rotor can be simply and rapidly manufactured. 
     If a rotor shaft has a driver, the torque can be advantageously transmitted from the rotor to the rotor shaft. 
     It is also advantageous if the stay has a securing piece, which extends through an opening of the tubular element, because this axially secures the stay. 
     By means of a bayonet connection between the ring and the securing piece, the stay is advantageously pressed against the magnets and the tubular element and is thus secured radially. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Two exemplary embodiments of the invention are shown in simplified fashion in the drawings and are explained in detail herein below, in conjunction with the drawings, in which: 
     FIG. 1 shows a bottom part, which is part of a rotor according to the invention, with a rotor shaft, 
     FIG. 2 shows a tubular element with mounted stays, magnets, and a ring, 
     FIG. 3 shows a ring, 
     FIG. 4 shows a bottom part with a mounted tubular element, stays, magnets, and a ring, 
     FIG. 5 shows a rotor according to the invention when assembled, 
     FIG. 6 shows a radial cross section along the line VI—VI in FIG. 4, 
     FIG. 7 shows an axial cross section along the line VII—VII in FIG. 5, 
     FIG. 8 shows a tubular element of a second exemplary embodiment of a rotor according to the invention, 
     FIG. 9 shows a tubular element with a support bushing and magnets, 
     FIG. 10 shows magnets, which are encompassed by stays on a tubular element, 
     FIG. 11 shows a ring, which fastens the stays to a tubular element, 
     FIG. 12 a  shows a top or bottom part and FIG. 12 b  shows how the ring of FIG. 11 is disposed on a tubular element, 
     FIG. 13 shows an arrangement according to FIG. 11, with a top or bottom part, 
     FIG. 14 a  shows a completed rotor, without a mounted rotor shaft and FIG. 14 b  shows the rotor with a mounted rotor shaft, and 
     FIG. 15 shows a completely assembled rotor according to the invention, with a rotor shaft. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a bottom part  4  of a rotor  1  (FIG. 5) with a rotor shaft  7 . The rotor shaft  7  is inserted into the bottom part  4  and fastened in it, and has a central axis  9 , which also constitutes, for example, a symmetry axis for the bottom part  4  or the rotor  1 . The stepped bottom part  4  has a cylindrical part  12  and a radial collar  15  adjoins its one axial end. For example, the bottom part  4  is made of plastic or metal. 
     An outer surface  20  of the cylindrical part  12  is provided with at least one groove  24  that extends parallel to the central axis  9 . In this exemplary embodiment, there are four grooves  24 . 
     In addition, the outer surface  20  is provided with at least one rib  36  that extends parallel to the central axis  9 . 
     The cylindrical part  12  has at least one spring rib  28  that can be elastically or elastically/plastically deformed, which is used for tolerance compensation with a tubular element  38  that is to be mounted onto it (FIG.  4 ). The spring rib  28  can be provided on the outer surface  20 , on the rib  36 , or on one of the rails constituting the groove  24 . 
     The radial collar  15  has bores  31  into which balancing weights can be inserted so that the rotor can be balanced for installation in an electric motor. Oriented toward the cylindrical part  12 , the radial collar  15  has an at least partially continuous circumferential groove  34 , which produces a positive engagement with the components mounted onto the cylindrical part  12 . 
     FIG. 2 shows a tubular element  38  that has at least one magnet  40  disposed on it, which is coupled by means of at least one stay  45 . In this exemplary embodiment, there are four magnets  40  and four stays  45 , which are arranged in alternation on the tubular element  38 , and at least one of the stays  45  does not touch the tubular element  38 . On their side surfaces extending in the direction of the central axis  9 , the magnets  40  and stays  45  have contours, e.g. in the form of a dovetail, so that these side surfaces of the magnets  40  and stays  45  engage one another with positive engagement. The tubular element  38  can also be comprised of a number of parts. 
     The stay  45  has at least one axial tab  48  protruding axially beyond the magnets  40 , which is embodied, for example, in the shape of a collar oriented toward the tubular element  38  and is engaged by a ring  42 . The tab  48  can, for example, be embodied at both axial ends of the stay  45 . 
     The ring  42  is thus disposed in front of the end surfaces of the magnets  40  and does not protrude beyond an outer circumference of the attached stays  45  or magnets  40 . The ring  42  secures the magnets  40  by means of constant pressure against the tubular element  38  by exerting a radial force on the stays  45 , which the stays  45  transmit to the magnets  40 . 
     For example, the magnets  40  are embodied in the form of arc segments and fit the shape of the tubular element  38 . 
     The magnets  40  and stays  45  constitute a positive engagement so that the forces during operation of the rotor  1  are distributed uniformly over contact surfaces of the magnets  40  and stays  45 . 
     For example, the tab  48  has at least one projection  49 , which protrudes beyond an end surface of the magnet  40  and thus secures the magnet  40  axially. For example, the tab  48  in FIG. 2 has two projections  49 . The tab  48 , which is provided for example on the opposite end of the stay  45 , can be embodied in a similar fashion. 
     The tubular element  38  is advantageously embodied as a tubular ring and has at least one protrusion  52  oriented toward the central axis  9 . 
     For example, the tubular element  38  is made of plastic or metal. If the tubular element  38  is magnetically conductive, it serves as a retaining element. 
     FIG. 3 shows the ring  42 . For example, the ring  42  is a spring ring  42  and when not deformed, is embodied as circular, for example (not shown). 
     An inner diameter of the ring  42  is greater than an outer diameter of the tubular element  38  and less than a diameter of an imaginary circular circumference line, which is determined by an outer surface of the axial tabs  48 . 
     Through forces, indicated by the arrows  55 , being exerted at for example four points  56  of the ring  42 , which are distributed for example evenly around an outer diameter, the ring  42  is deformed by means of an installation grasping tool so that the ring  42  can be slid over the axial tabs  48  of the stays  45 . Between the points  56 , the ring  42  bulges out and thus fits over the axial tabs  48 . When the exertion of the forces is released, the spring ring  42  attempts to return to its original shape and thus exerts a force, which engages the stays  45  in the direction of the central axis  9 . 
     For example, two rings  42  are provided, which are attached to the two axial ends of the rotor. 
     If the stays  45  are embodied of one piece with the top part ( 64 ) or the bottom part ( 4 ), then one ring  42  is provided. 
     The ring  42  can also be embodied as a rigid ring  42 , which is then pressed over the axial tabs  48  of the stays  45 . 
     FIG. 4 shows the individual parts shown in FIGS. 1 and 2 when they are assembled. That is, the bottom part  4  with the rotor shaft  7  is slid into the tubular element  38 , which is provided, according to FIG. 2, with magnets  40 , stays  45 , and spring rings  42 . The radial protrusions  52  of the tubular element  38  are slid into the groove  24  of the bottom part  4 . These protrusions  52  transmit the torque of the magnets  40 , which is produced in an external excitation field of a stator of an electric motor, to the bottom part  4  and therefore to the rotor shaft  7 . 
     The components according to FIG. 2 rest with the end surface of the tubular element  38  in the circumferential groove  34 . The tubular element  38  engages positively with the bottom part  4  by means of the deformable spring ribs  28 . When assembled, the circumferential groove  34  and the collars  15  cover the region of the non-round ring  42  and the tabs  48  of the stays  45  and thus, by forming a smooth surface, prevent blade losses of the rotor  1  when the rotor rotates in a fluid. At the same time, the rings  42  are secured axially. For example, the bottom part  4  has four hooks  59 , which are part of a detent connection with a top part  64  (FIG.  5 ). 
     FIG. 5 shows a rotor  1  according to the invention when assembled with the top part  64 . 
     For example, the top part  64  is embodied in the shape of a disk and has appropriate openings for the hooks  59  of the bottom part  4  to engage in so that a detent connection is produced by means of which the top part  64  fixes the tubular element  38  to the bottom part  4 , along with the magnets  40 , stays  45 , and spring rings  42 . 
     For example, the top part  64  also has bores  31 , into which balancing weights can be inserted. 
     Like the collar  15  of the bottom part  4 , the top part  64  has a corresponding circumferential groove  34  with the same purpose of covering the other ends of the tubular element  38 , magnets  40 , stays  45 , and the spring ring  42 . 
     FIG. 6 shows a radial cross section along the line VI—VI in FIG.  4 . 
     FIG. 6 shows the cross section of the stays  45 , which is, for example, the same over the entire length. The stays  45  form a positive engagement with the magnets  40  and produce, for example, a circular circumference line. In addition, at least one of the stays  45  has at least one pin  67 , which engages in a corresponding recess  68  of the tubular element  38  and thus secures the stay in its position. These pins  67  simultaneously serve to position the magnets  40  on the tubular element  38 . In the production of the recess  68  for the pins  67 , the radial protrusions  52  of the tubular element  38  can be produced, for example by means of stamping, in that the material of the recess  68  is pressed out toward the central axis  9 . 
     The protrusion  52  of the tubular element  38  engages in the groove  24 , but does not necessarily rest with its end surface against the outer surface  20  of the bottom part  4 . At least a part of a side surface of the protrusion  52  rests snugly against the groove  24  so that here, too, as with the pin  67 , a torque can be directly transmitted. 
     The tubular element  38  rests against the ribs  36 . 
     Tolerance-induced differences between the inner diameter of the tubular element  38  and the radial span of the ribs  36  are compensated for by the deformation of the at least one spring rib  28 . 
     FIG. 7 shows a section along the line VII—VII in FIG.  5 . 
     The circumferential grooves  34  of the top part  64  and bottom part  4  respectively encompass the axial tabs  48  of the stays  45  and the rings  42 . 
     For example, the cylindrical part  12  of the bottom part  4  is embodied as a hollow body, with corresponding bores for the rotor shaft  7  and lateral struts to the outer surface  20 . 
     The position of the magnet  40  is indicated with dashed lines in this figure. It is clear that the ring  42  rests not against the magnet  40 , for example, but only against the stay  45 . 
     A second exemplary embodiment is shown in FIGS. 8 to  15 . 
     FIG. 8 shows the tubular element  38 , which has at least one opening  72  in its wall. For example four stays  45  (FIG. 10) are placed against the tubular element  38  and have, for example, two securing pieces  82  (FIG. 10) disposed against the stay  45 , which securing pieces  82  are inserted through the openings  72 . The openings  72  are evenly distributed over the circumference of the tubular element  38 . In the axial direction, for example two openings  72  are provided one above the other for the respective stays  45 . 
     Here, too, the tubular element  38  can serve as a magnetic retaining element. 
     By way of example, FIG. 9 shows four magnets  40 , which are distributed evenly spaced apart from one another on the tubular element  38 . The apparatus is not limited to four magnets  40 ; there can also be fewer or more magnets  40 . 
     A support bushing  75  is placed or press-fitted into the tubular element  38 . The support bushing  75  is comprised, for example, of a support bushing ring  76 , which has a smaller diameter than the tubular element  38  and a number of support bushing struts  77  directed radially outward, which rest against an inner surface  79  of the tubular element  38 . 
     Based on FIG. 9, FIG. 10 shows how the four stays  45  are disposed against the magnets  40  and the tubular element  38 . 
     The stay  45  is embodied similarly to the stay  45  described in FIG. 2, but without tabs  48 . The function and mechanism are also similar. 
     The stay  45  of the second exemplary embodiment also has at least one securing piece  82  extending radially inward, which is guided through the opening  72  of the tubular element  38  and has a free end  86 . In this exemplary embodiment, the stay  45  has two securing pieces  82 , which are disposed in the vicinity of axial ends  87  of the stay  45 . 
     As a result, the stay  45  is secured axially and can be pressed against the magnets  40  and the tubular element  38  very well at both axial ends  87 . 
     A part of the securing piece  82  is thus disposed inside the tubular element  38 . The free end  86  of the securing piece  82  is provided with an axial extension  85 , which extends in the axial direction toward an opening of the tubular element  38  and forms a notch  88  with an inner surface  79  of the tubular element  38 . 
     In addition, the free end  86  has a projection  91  extending from it, which is directed radially inward. 
     FIG. 11 shows how the stays  45  are connected in a frictionally engaging manner to the tubular element  38  by means of the ring  42 . 
     The ring  42  is disposed inside the tubular element  38 . 
     The ring  42  is comprised of at least one tensioning part  95  and at least one connecting piece  97 , which connects the individual tensioning parts  95  to one another and is thus embodied so that it can be elongated or stretched. 
     The tensioning part  95  is inserted into the notch  88  and is rotated around the central axis  9  so that the tensioning part  95  is pressed between the inner surface  79  of the tubular element  38  and the axial extension  85  and thus constitutes a bayonet connection with the notch  88 . To this end, either the tensioning part  95  or the notch  88 , or the tensioning part  95  and the notch  88  are embodied in the form of a wedge. In this instance, the respective tolerances of a stay  45 , tubular element  38 , and magnets  40  are compensated for individually. 
     The stay  45  is now also secured radially. 
     The connecting pieces  97  do not necessarily have to be provided. The tensioning parts  95  can also be installed individually. 
     For example, the securing piece  82  can rest against the support bushing  75 —the support bushing ring  76  in this example—so that the securing piece  82  cannot warp. The length of the support bushing  75  is thus adapted to the axial spacing of the securing pieces  82 . 
     The support bushing  75  also absorbs the bending moments that are exerted by the stays  45  onto the magnets  40  and by the magnets onto the tubular element  38 . 
     FIG. 12 a  shows the top part  64  or the bottom part  4 , which has at least one spring rib  28  extending in the radial direction on ribs  36 , against which the tubular element  38  rests (FIG. 12 b ), thus permitting a tolerance compensation. 
     In addition, the top part  64  and the bottom part  4  have at least one projection opening  92 , which is disposed inside the tubular element  38 . 
     FIG. 13 shows how the bottom part  4  or the top part  64  is mounted onto the apparatus according to FIG.  11 . The projection  91  engages in a projection opening  92  of the bottom part  4  or the top part  64  and thus produces a positive engagement with the projection opening  92 . 
     The bottom part  4  or the top part  64  rests against the magnets  40  and thus secures the magnets  40  axially. 
     FIG. 14 a  shows the rotor shaft  7  on which a driver  101  is disposed, which with an apparatus according to FIG. 13, is mounted to the top part  64  and bottom part  4 , which each have a corresponding opening  102  for the rotor shaft  7 . 
     The driver  101  has at least one driver projection  103 , which engages in a corresponding driver recess  105  on the top part  64  or bottom part  4  and forms a positive engagement there. Depending on the number of driver projections  103 , for example, the corresponding number of driver recesses  105  is provided. 
     FIG. 14 b  shows how the rotor shaft  7  is put together with the rotor  1  and how the driver  101  engages in the bottom part  4  or the top part  64 . 
     FIG. 15 shows the other axial end of the rotor  1  from FIG. 14 b . At the other axial end of the rotor shaft  7 , a snap ring  109  is provided, which engages in a recess of the rotor shaft  7  and secures the top part or bottom part in the axial direction on the rotor shaft  7  so that the driver projection  103  remains in its driver recess  105 . 
     When a torque is exerted on the magnets  40  of the rotor  1  by means of a magnetic field of a stator, the tubular element  38  rotates because the stay  45  connects the magnets  40  to the tubular element  38 . The securing piece  82  likewise rotates due to the rotary motion of the tubular element  38 . The securing piece  82  is connected to the bottom part  4 , for example, with positive engagement by means of the projection  91  and the projection opening  92 . The rotor shaft  7  is secured to the bottom part  4  by means of the driver  101  so that the rotor shaft  7  also turns as a result. The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.