Patent Application
20120014823
This claims the benefit of German Patent Application DE 10 2010 031 399.8, filed Jul. 15, 2011 and hereby incorporated by reference herein.
The invention relates to a rotor for an electric motor, especially for a permanently excited electric motor. The invention also relates to a production process for a rotor or for an electric motor.
A rotor of the above-mentioned type for a permanently excited electric motor is known, for example, from Japanese patent JP 2005 012859. It is a known procedure to use various adhesion, welding or laminating techniques to affix a rotor core to a rotor shaft, or to arrange core laminations of the rotor core on each other. In Japanese patent 2002 354722, a rotor core is connected to the rotor shaft by means of a plastic transfer-molding process. It is also a known procedure to compression-mold a rotor core onto a smooth or knurled rotor shaft.
In a permanently excited electric motor such as, for example, a BLDC or BLAC electric motor, a permanent magnet can be inserted into a chamber of the rotor core formed with a receiving opening and affixed there. Receiving openings—as shown in WO 2006/090567 A1—can form an obliquely oriented chamber or can be oriented at different angles of inclination relative to a central recess of the rotor core through which the shaft passes.
A problematic aspect of the above-mentioned types of connection is fundamentally the relatively laborious assembly. Thus, when individual core laminations are attached in order to form the rotor core on a rotor shaft, the tolerances cannot be ascertained sufficiently precisely, which usually calls for a subsequent work step, namely, the labor-intensive balancing of the rotor. During the balancing procedure, in particular, the placement of balancing weights onto the rotor can entail drawbacks for the later operation. The rotor position is usually detected by using a Hall sensor on the stator of the electric motor to detect the position of the rotor relative to the stator. During operation, this is used to control a magnetic coupling between the rotor and the stator, that is to say, to control the electric motor.
Moreover, it is regularly necessary to carry out a laborious adjustment of the permanent magnets relative to each other so that a rotor position can be detected very precisely during the operation of the electric motor. Merely gluing or clamping a permanent magnet in a peripheral receiving opening of the rotor core or of a core lamination has proven to be inadequate in this context. Here, the conditions for a secure fixation of a permanent magnet differ from the conditions for a precise positioning of a permanent magnet. The former regularly require more space, while the smallest possible space tolerance is preferred for the latter. It would be desirable to have a rotor core that makes it possible to achieve a simultaneously secure and yet precise attachment onto the rotor shaft and/or the formation of a receiving element for a pole-forming element on the rotor core. It would also be desirable to have the most simplified production process possible for an improved rotor or electric motor. If possible, there should be no need to readjust or balance a rotor after the rotor shaft and the rotor core have been assembled with permanent magnets.
It is an object of the present invention to provide a rotor, an electric motor and a production process for a rotor or for an electric motor in which the production of a rotor or electric motor is simplified and yet, the manufacturing tolerance and/or manufacturing quality of the rotor or electric motor are ensured to a sufficient extent.
In particular, the adjustment or balancing steps that have been needed in a production process until now should be avoided or reduced, and yet, the production of a rotor or electric motor with a sufficient or improved manufacturing precision should be made possible.
In particular, an arrangement of a permanent magnet relative to a core lamination should be ensured in a sufficient or improved manner, and yet, it should be simplified in terms of its production. In particular, a rotor core should be affixed onto the rotor shaft as securely as possible—axially as well as radially—and with a sufficient manufacturing tolerance. In particular, the magnetic field conditions should be improved; in this context, it should preferably be possible to adhere to minimum values for air distances and creepage distances. In particular, the positioning of a fan and/or of a bearing relative to the rotor core should be simplified as well as secure, and yet, it should be ensured that the tolerance is sufficient.
The present invention provides that the rotor core has an uneven surface oriented towards the rotor shaft, and this surface is formed, among other things, with adjacent areas and with contours of the central recess of the plurality of core laminations. This can especially comprise edges, inner surface areas and side areas or similar parts of adjacent areas around the central recess. The surface is essentially an inner circumferential side of the rotor core that faces an outer circumferential side of the rotor shaft.
In the area of the central recess, the especially rotated arrangement of at least some of the plurality of core laminations results in this uneven surface. It is especially formed by uneven areas in the axial direction of the rotor core in which at least some of the plurality of core laminations are not arranged congruently to each other with respect to the central recess. The concept of the invention provides that a first core lamination has to be made to coincide congruently relative to a second core lamination in terms of the receiving structure in order to form a receiving element for a pole-forming element on the rotor core, while, with such an especially rotated arrangement of a first core lamination and a second core lamination, the contour of the central recess does not come to lie congruently with each other. This leads to a preferred above-mentioned uneven surface in the axial direction of the rotor core.
According to a refinement, it is provided, for example, that, at least in part, core laminations are rotated with respect to each other according to a multiple rotational symmetry of the receiving structures—at least a first core lamination is rotated relative to a second core lamination, for example, in case of a four-fold rotational symmetry, by 90°, with respect to each other. According to the concept of this refinement, it is provided that a contour of the central recess does not follow the multiple rotational symmetry of the receiving structures.
The concept can be carried out especially on the basis of the refinements explained below by way of examples.
In particular, a contour of the central recess can diverge irregularly from a circular shape. It has proven to be especially advantageous for a contour to differ from an even-numbered rotational symmetry and to have an odd-numbered rotational symmetry. In particular, the central recess of a core lamination can have a contour in the form of a polygon or a convex arc-polygonal orbiform curve. A Reuleaux triangle or a pentagon or a seven-cornered convex arc-polygon or a different orbiform curve have proven to be especially advantageous. The term orbiform curve especially refers to a contour having a constant width—but not a circle—in which all of the possible diameters have the same value. In particular, the number of sides is an odd number and all of the sides have the same length. A particularly suitable contour of the central recess is one that runs with a roundness deviation between an inscribed circle having an inner diameter and a circumscribed circle having an outer diameter. The roundness deviation is preferably greater than 0.1%, especially greater than 0.5%, especially smaller than 5%, especially smaller than 2%, of a mean value resulting from the inner diameter (Di) and the outer diameter (Da). This has proven to be especially advantageous for attaching the rotor core onto an optionally untreated surface of a rotor shaft.
For example, for a contour of the central recess, the polygonicity of a convex arc-polygon is selected in such a way that it does not coincide with the multiple rotational symmetry of the arrangement of the receiving structures for a pole-forming element. It has proven to be especially advantageous to select the combination explained in the drawing consisting of a four-fold rotational symmetry for receiving openings, permanent magnets or armature teeth for coil windings, and to select a pentagon or Reuleaux triangle for the contour of the central recess. With a four-pole rotor, the choice of a pentagonal convex arc-polygon is preferred for realizing the concept of the refinement. In a modification within the scope of the concept of the refinement involving a two-pole rotor, a Reuleaux triangle, that is to say, a triangular convex arc-polygon, can be selected for the contour of the central recess. Fundamentally, it has proven to be preferable for the multiple rotational symmetry for the receiving structures to be selected with an even number, and for the angularity of a convex arc-polygon for a central recess to be selected with an odd number. Preferably, the value of the even-numbered rotational symmetry for the receiving structure is “1” higher than the value of the odd-numbered rotational symmetry of the contour of the central recess. Such a combination for the configuration of the rotational symmetry of the receiving structures, on the one hand, and the contour of the central recess, on the other hand, has proven to be especially advantageous for a radially and axially secure attachment of a rotor core onto a rotor shaft. In particular, manufacturing tolerances can be adhered to properly, taking minimum values for air distances and creepage distances into account, so that magnetic stray fields and other losses are largely avoided. It has also turned out that a surface in the axial direction of the rotor core is so uneven on an inner circumferential side that a complex gap is formed in comparison to an essentially smooth and cylindrical outer circumferential side of the rotor shaft. Depending on the requirements, the gap can be used for inserting transfer-molding compound during the fixation of the rotor core onto the rotor shaft, or for inserting excess flow material during the interference fit of a rotor core onto a rotor shaft. Advantageously, during the production, a rotor core can also be securely affixed without a special surface treatment of the rotor shaft—for example, knurling the outer circumferential side of the rotor shaft.
The concept of the invention also yields an electric motor, especially a permanently excited electric motor, for example, a BLDC or BLAC electric motor. It has a magnetically coupled arrangement of a stator and a rotor, said rotor being configured according to the concept of the invention explained above, and said stator having a plurality of stator poles associated with one pole pair of the rotor.
This electric motor has greater power as a result of its more reliable and precise assembly, especially since the production process allows better magnetic field conditions, and the minimum values for the air distances and creepage distances are adhered to because of the precise manufacturing tolerances.
The concept of the invention also yields a hand-held power tool with an electric motor according to the concept of the invention.
In order to achieve the object in terms of the production process, the concept of the invention puts forward a production process of the type described above, with which a rotor and/or an electric motor can be produced relatively simply in an especially advantageous manner, and yet, the rotor core can be attached onto the rotor shaft especially securely and with high precision.
The production process for an electric motor provides for the magnetically coupled arrangement of the rotor produced according to the invention and having the stator, said stator having a plurality of stator poles associated with one pole pair of the rotor.
According to the invention, the production process for a rotor comprises the following steps:
The concept of the production process according to the invention ensures—aside from the advantageous attachment of the rotor core onto the rotor shaft as explained above—the formation of a continuous chamber to receive a permanent magnet, in spite of the rotating of the core laminations with respect to each other. At least two, preferably four or a higher, even number of permanent magnets is provided in order to form at least one pole pair on the rotor core. Especially advantageously, a particularly good fixation of the rotor core onto the rotor shaft is ensured by assembling and affixing the core laminations relative to each other and to the rotor shaft, and then additionally by transfer molding a transfer-molding compound axially and/or radially around the laminated core. This can be achieved especially preferably by means of a suitable transfer-molding process.
Particularly preferably, by means of additional advantageous measures, a permanent magnet can be positioned especially securely and precisely in a chamber formed by the receiving openings of the laminated cores. The conditions regarding dimensional stability and secure fixation of a permanent magnet, which seem to be contradictory to each other, can be very advantageously reconciled with each other in a chamber.
Additional advantageous refinements of the inventions can be gleaned from the subordinate claims, and they provide details of advantageous possibilities for realizing the above-mentioned concept within the scope of the object as well as in terms of additional advantages.
Advantageously, the rotor core is attached onto the rotor shaft by means of transfer molding and/or interference fit. When it comes to achieving a transfer molding and/or an interference fit, it has proven to be especially preferable for the value of an outer diameter of the rotor shaft to fall between an inner diameter of an inner cylinder defined by an inscribed circle and an outer diameter of an outer cylinder defined by a circumscribed circle, said cylinders being associated with the surface of the rotor core facing the rotor shaft. Especially advantageously, a gap formed between the rotor shaft and the contour of the recess can be thus filled with transfer-molding compound. In addition or as an alternative, a pressing surface of the recess adjacent to the contour can be pressed against the rotor shaft, especially deformed continuously.
Preferably, the gap has the dimension of a roundness deviation as mentioned above. As explained, it is preferably defined such that the contour of the central recess runs with a roundness deviation between an inscribed circle thereof having an inner diameter and a circumscribed circle thereof having an outer diameter. The roundness deviation is preferably greater than 0.1%, especially greater than 0.5%, especially smaller than 5%, especially smaller than 2%, of a mean value resulting from the inner diameter and of the outer diameter.
Within the scope of an especially preferred refinement, it is provided that a core lamination additionally has a plurality of encoding markings on the basis of which the first core lamination can be secured relative to the second core lamination so as to be rotated. Preferably, the first and second core laminations are rotated relative to each other while each forming a chamber in the rotor core through which the permanent magnet passes.
The term encoding marking arrangement fundamentally refers to any suitable defining marking on a core lamination—especially as a structural configuration of the core lamination—which is provided in addition to the features of the generic part of claim 1, and which is also configured so as to ensure that the relative arrangement of the core laminations with respect to each other is sufficiently precise when they are rotated. Preference is given to an encoding marking that is simultaneously suitable as a stop means of a core lamination—be it on another core lamination or on a production means. For example, if the core lamination with the encoding marking reaches a stop on a production means such as a transfer mold or the like, the first core lamination can be secured relative to the second core lamination so as to be rotated, and/or the rotor core can be secured on the production means. Advantageously, the first core lamination and the second core lamination are secured by means of the encoding marking, especially with a peripheral encoding recess, especially as an edge recess, on the production means such as, for example, a transfer mold. Thus, the rotor core can be inserted into a transfer mold, i.e. the individual insertion of a core lamination, so as to be encoded according to the encoding marking arrangement. The encoding marking arrangement can also be used to secure a first core lamination onto a second core lamination. The encoding marking arrangement makes it possible to reliably assemble the core laminations during the production process so that they are sufficiently secured relative to each other, and to affix them in this position with the requisite manufacturing tolerance.
Due to an assembly position of the core laminations that has been thus encoded, the rotor core can be created and the subsequent production steps of the rotor can be carried out in a simplified manner. In particular, the need for additional adjustments can be reduced since the assembly with the encoding marking is already performed with sufficient precision. In particular, a plurality of additional encoding markings that are harmonized with each other can be prescribed for other parts of the rotor in order to simplify the relative positioning of the rotor core, especially relative to the fan and/or the stator. A rotation of the first and second core laminations relative to each other also forms the basis to improve the attachment of the rotor core onto the rotor shaft, and yet to simplify the production of the rotor.
During the production process, it is especially preferred for a core lamination to have an encoding marking arrangement according to a multiple rotational symmetry of the permanent magnet arrangement or according to a multiple rotational symmetry that conforms thereto, that is to say, in such a manner that the first and second core laminations are rotated relative to each other while each forming a chamber in the rotor core through which a permanent magnet passes. Thus, a core lamination that has a plurality of encoding markings can be inserted into a transfer mold in order to form the rotor core in a manner that is encoded on the basis of the plurality of encoding markings, and the first core lamination can be arranged rotated relative to the second core lamination and with a plurality of receiving openings that are arranged congruently to each other, so that the receiving openings that are arranged congruently to each other form the chamber in the rotor core through which the permanent magnet passes.
It has proven to be especially preferable for the plurality of receiving openings to be arranged at first peripheral angular positions according to an even-numbered rotational symmetry. Preferably, the plurality of encoding markings at second peripheral angular positions are arranged according to the even-numbered rotational symmetry or according to a lower even-numbered rotational symmetry. The central recess through which the rotor shaft passes preferably has a contour that has an odd-numbered rotational symmetry. An especially preferred surface of the rotor core facing the rotor shaft is formed if, according to this refinement of the invention, the first and second core laminations are rotated relative to each other according to the even-numbered rotational symmetry.
The non-rotatable arrangement of the core laminations by means of the encoding markings ensures that a first core lamination can be arranged relative to the second core lamination with a sufficient manufacturing tolerance during the production process, without there being a need for a readjustment or a subsequent balancing procedure for a rotor core; in any case, however, such an effort is reduced. Nevertheless, the encoding marking arrangement advantageously allows any desired rotated arrangement of the first core lamination relative to the second core lamination, for example, within a predefined multiple rotational symmetry, so that this simplifies the production step.
The term multiple rotational symmetry refers to a rotational symmetry that, when a first core lamination is rotated relative to a second core lamination, nevertheless causes the receiving openings for permanent magnets or the encoding marking arrangement to coincide essentially congruently. In particular, this refers to an even-numbered rotational symmetry, that is to say, for instance, a two-fold, four-fold, six-fold, eight-fold, etc. rotational symmetry. One speaks of an n-fold rotational symmetry when a rotation by 360°/n projects the receiving openings or the encoding marking arrangement of the core lamination onto themselves. For example, in the case of a four-fold rotational symmetry, after a 90° rotation, the receiving openings of a first core lamination each have to be made to coincide congruently with the receiving openings for a permanent magnet of a second core lamination. The above-mentioned example of a four-fold rotational symmetry relates, for example, to the arrangement of four permanent magnets in four recesses of a rotor core in a 90° position with respect to each other. In that case, it is a four-pole version of a rotor with four permanent magnets held in a rotor core. One embodiment that explains this refinement by way of an example is described on the basis of the drawing. The concept of the invention, however, is not fundamentally limited to a specific number of poles, but rather can fundamentally refer to any desired multiple rotational symmetries—for example, also odd-numbered ones—although even-numbered rotational symmetries are especially preferred as will be explained below. A receiving opening for a permanent magnet can fundamentally be oriented as needed, for example, along a radius of the core lamination or along a secant of the core lamination. A recess for a permanent magnet or for some other receiving structure for a pole-forming element can also be arranged at an angle that differs from 90° or 180° relative to a radius of the core lamination, that is to say, obliquely to it. The latter does not affect the determination of the value of the rotational symmetry of the receiving openings or of the encoding marking arrangement.
Especially preferably, the at least one encoding marking arrangement is formed with a plurality of peripheral encoding recesses. A peripheral encoding recess in a core lamination is especially well-suited for securing the core lamination, for example, onto a transfer mold or for securing a first core lamination and a second core lamination relative to each other by means of the encoding recess.
It has proven to be especially preferred to have a plurality of peripheral encoding recesses that is formed with a plurality of edge recesses. The arrangement of the core lamination that takes manufacturing tolerances into account, especially in a transfer mold, is ensured in that a web of the transfer mold engages into the edge recess, thereby affixing the core lamination in the transfer mold. By stacking the plurality of core laminations on top of each other, a rotor core is created with a groove formed in the circumferential area of the rotor core by the edge recesses, said groove being held in a web of the transfer mold. Fundamentally, the arrangement of the groove and the web on the rotor core and on the transfer mold can be reversed. This is possible as long as the web does not have a detrimental effect on the rotor core or as long as it can be compensated for. According to this preferred embodiment, the core laminations can already be stacked by means of the encoding marking arrangement, within the framework of the manufacturing tolerance. A readjustment or a balancing procedure is not required; in any case, such separate correction steps are considerably reduced.
Moreover, it is preferable for a plurality of peripheral lamination points, especially holes or the like, to be formed at a distance from the edge. They can be filled with transfer-molding compound and can assist in securing a first core lamination relative to a second core lamination in a way that complies with the manufacturing tolerance, i.e. in the form of a non-rotatable arrangement of a first core lamination relative to a second core lamination within the framework of a prescribed manufacturing tolerance. Preferably, a lamination point is formed radially between a receiving opening through which a permanent magnet passes and the central recess through which the rotor shaft passes. This arrangement of the lamination points has proven to be especially suitable for creating a stable rotor core.
Especially preferably, a rotor core—as an edge core lamination—has an initial core lamination that, like the other multiple core laminations, also has a central recess through which the rotor shaft passes and which is arranged in the initial core lamination. Furthermore, at least one rectangular receiving opening is provided that is arranged peripherally in the initial core lamination and through which a permanent magnet passes. The essentially rectangular receiving opening surrounds an essentially rectangular permanent magnet with a practically precise fit. It is advantageously possible to leave some play all the way around the fit, so as to create a filling gap around a permanent magnet in order to use transfer-molding compound to securely affix said permanent magnet in the essentially rectangular receiving opening of the initial core lamination. In addition or as an alternative, a web that divides the receiving opening and/or a lateral bevel can be provided in order to axially affix the permanent magnet.
Preferably, a multiple core lamination of the plurality of core laminations is provided with a peripheral, essentially rectangular receiving opening through which a permanent magnet passes. Preferably, the essentially rectangular receiving opening has a lateral bulging section for receiving transfer-molding compound. In addition or as an alternative, the essentially rectangular receiving opening can also have a lateral cutaway section that is also suitable for receiving transfer-molding compound. A transfer-molding process can advantageously be used in this way in order to laterally affix a permanent magnet with sufficient transfer-molding compound for most of the rotor core.
Advantageously, the rotor core, as an edge core lamination, has a final core lamination that, like the other multiple core laminations, has a central recess through which the rotor shaft passes and which is arranged in the final core lamination. Furthermore, at least one essentially rectangular receiving opening is provided that is located peripherally in the final core lamination and that is associated with a permanent magnet—although advantageously, the permanent magnet does not pass through said rectangular receiving opening. The receiving opening preferably has a lateral bevel and/or a web that divides the opening. The lateral bevel and/or the web can hold a permanent magnet in the axial direction. All in all, the combination of an initial core lamination with a final core lamination and the at least partially rotated multiple core laminations in the rotor core ensures a lateral and axial fixation of a permanent magnet.
Within the scope of an especially preferred refinement, the rotor shaft has a bearing mount and/or a fan mount, especially a ball bearing mount. Preferably in the area of the bearing mount, the rotor shaft has a splined shaft. Preferably in the area of the fan mount, the rotor shaft has an encoding on the basis of which a fan wheel is to be arranged so as to be non-rotatable relative to the rotor shaft. In particular, the encoding conforms to the multiple rotational symmetry so that especially a fan wheel can be arranged so as to be non-rotatable relative to the receiving opening through which a permanent magnet passes. For example, the encoding of the bearing mount and/or fan mount can comprise a number of webs that is equal to the number of permanent magnets. For example, the encoding of the bearing mount and/or fan mount can have at least one flat side that is parallel to an orientation of a permanent magnet.
In particular, it has proven to be advantageous for a fan wheel installed on the rotor shaft to have a fan magnetic ring with poles and/or to have fan blades that are arranged according to the multiple rotational symmetry. The encoded bearing mount and/or fan mount reduces the work involved in a readjustment for the fan magnetic ring in order to position it precisely relative to the arrangement of the permanent magnets in the rotor core, since, in accordance with the encoding, all of the poles are preferably already arranged at the same angular positions. This refinement can be achieved especially easily in that the fan magnetic ring and/or the permanent magnets are only magnetized after the transfer molding process has been completed. In this manner, thanks to the encoding marking arrangement and/or the encoding for the fan mount, the premature magnetization of a permanent magnet or of the fan magnetic ring does not unnecessarily interfere with the precise arrangement relative to each other.
Preferably, the fan wheel also has fan blades that are arranged at peripheral angular positions of the permanent magnets or of other pole-forming elements on the basis of the encoding of the fan mount. Thus, it is possible to realize an electric motor—especially a permanently excited, BLDC or BLAC electric motor—which is especially advantageously cooled on the outside.
Preferably, when it comes to the electric motor, the rotor is placed into a magnetically coupled arrangement with respect to the stator, and the stator has a plurality of stator poles according to the multiple rotational symmetry. During operation, the stator poles are associated with alternating rotor poles, each in accordance with their rotation. Until now, the adjustment of the stator poles relative to the rotor poles has proven to be relatively laborious. This adjustment is normally carried out using a Hall sensor that is installed on the stator. According to an especially preferred embodiment, it is provided that a stator encoding secures at least one Hall sensor relative to the plurality of stator poles. In particular, a Hall sensor can be secured by the stator encoding exactly between two stator poles. Here, it is advantageously possible to dispense with a readjustment. Within the scope of an especially preferred variant, it has proven to be advantageous for a Hall sensor to be arranged on a printed circuit board that is secured relative to a carrier plate by means of plate encoding. Furthermore, the carrier plate is secured relative to the plurality of stator poles on the basis of the above-mentioned stator encoding. The preferred embodiment of such a refinement is explained with reference to the drawing.
Embodiments of the invention will be described below on the basis of the drawing. The drawing does not necessarily depict the embodiments true-to-scale, but rather, it is presented in schematic and/or slightly distorted form whenever this serves for purposes of illustration. Regarding additions to the teaching that can be derived directly from the drawing, reference is hereby made to the pertinent state of the art. In this context, it should be taken into consideration that many modifications and changes can be made in terms of the form and the details of a given embodiment, without departing from the general idea of the invention. The features of the invention disclosed in the description, in the drawing as well as in the claims, be it individually or in any desired combination, can all be essential for refining the invention. Moreover, all combinations of at least two of the features disclosed in the description, in the drawing and/or in the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or details of the preferred embodiment shown and described below, nor is it limited to a subject matter that would be restricted in comparison to the subject matter claimed in the claims. Regarding the dimensional ranges given, values that fall within the cited limits can also be disclosed as limit values and can be employed and claimed as desired. For the sake of simplicity, the same reference numerals will be used below for identical or similar parts or for parts having an identical or a similar function.
Additional advantages, features and details of the invention can be gleaned from the description below of the preferred embodiments as well as on the basis of the drawing. The following is shown:
On a side of the fan wheel 60 opposite from the fan blades 61, a magnetic ring 62 is incorporated whose four-pole configuration with opposing north (N) and south (S) poles can be seen from a front view in
For this purpose,
The depiction in
The central recess 70 has a contour 71 of a pentagon that is explained with reference to
In this vein, as shown in a perspective view of
The above-mentioned encoding by the four webs 36 on the fan seat 35 of the bearing and fan mount 33 ensures that the fan wheel 60 and thus the magnetic ring 62 and its pole orientation correspond precisely with the pole arrangement of the rotor core 20 formed by the permanent magnets 39. Correspondingly,
In the production process, the bearing 50 and subsequently the fan wheel 60 can be slid onto the bearing and fan mount 33 that is provided with encoding, said encoding ensuring that—irrespective of the choice of one of the rotational positions defined by the four webs 36—the pole orientation of the magnet ring 62 of the fan wheel 60 corresponds to the pole orientation of the rotor core 20.
During the installation of the electric motor 1000, which is cooled on the outside, the fan wheel 60 on the projecting end of the rotor shaft is pressed onto the encoded fan seat 35 that has been attached to the bearing and fan mount 33, and ultimately, it is axially secured by means of a claw-like disc 63, as shown in
On the basis of the following
For this purpose, first of all,
The same applies as already mentioned for the edge recesses 91 of the core lamination 40. The edge recesses 91 that are created on an outermost edge 49 of the core lamination 40 are arranged so as to be offset by 90° according to the four-fold rotational symmetry. In the case of the edge recesses 91 as well, a core lamination 40 that is rotated by 90° comes to lie so as to coincide with a non-rotated core lamination 40, i.e. it is congruent in terms of the lamination points 90, in terms of the receiving openings 80 and in terms of the edge recesses 91.
With reference to
In the same way that the edge recesses 91 form the above-mentioned groove 21 on the outer circumferential side of the rotor core 20, the receiving openings 80 form an axial chamber extending along the rotor core 20 to hold a permanent magnet 39, also under the 90° rotation of adjacent core laminations 40 with respect to each other that is provided in the present case. In other words, the above-mentioned webs in the transfer mold serve as adjustment means for the core laminations 40 that are rotated with respect to each other, while engaging into the edge recesses 91. Thus, the edge recesses 91 form an encoding marking arrangement according to the four-fold rotational symmetry by means of which a first core lamination and a second core lamination 40 can be arranged non-rotatably relative to each other. The encoding marking arrangement in the form of the edge recesses 91 ultimately guarantees a dimensionally accurate configuration of the chambers to hold a permanent magnet 39 in the receiving openings 80.
As a result, an encoding marking arrangement is formed by means of the edge recesses 91 in such a way that, within the framework of the production accuracy, the core laminations 40 in the rotor core 20 are already arranged so as to be rotated relative to each other. However, the permanent magnets 39 can still be already positioned precisely in a chamber formed by the receiving openings 80, without a need for a readjustment or a balancing of the rotor 100.
An initial core lamination 40A, which is shown in
The receiving opening 80A is shown in a variant 80A′ in
In
The configuration of the multiple core lamination 40 in combination with the initial core lamination 40A achieves not only an especially dimensionally accurate configuration of a chamber to hold a permanent magnet 39, but also that a permanent magnet 39 is properly secured laterally through the adequate distribution of the transfer-molding compound 30, for example, in bulging sections 81 and cutaway sections 84 on different sides of the permanent magnet 39.
In
Such a joining process can fundamentally be used with any kind of rotor core according to the low-voltage guidelines. All in all, these measures result not only in a rotor core 20 that is configured so as to be dimensionally accurate with precisely arranged permanent magnets 39, but they also result in a rotor core 20 that is relatively stable in and of itself, with securely arranged permanent magnets 39 that are secured axially as well as radially. For purposes of better handling during the transfer molding of the rotor core 20 and of the rotor shaft 10, the permanent magnets 39 are at first not magnetized in the present case. As rod magnets, they can thus be more easily inserted into the rotor core 20, i.e. into the chambers formed by the receiving openings 80. Moreover, at first, there is no need to pay attention to the polarity of the permanent magnets 39. By the same token, there is no need for concern that adhesions will occur on the permanent magnet 39 during the transfer-molding process. Thus, especially the entrainment of dirt into a transfer mold is virtually ruled out. The rotor 100, which has been encapsulated by the molding process, as is shown in
A crucial aspect for an especially good attachment of the rotor core 20 onto the rotor shaft 10 is the formation of the central recess 70 in the core lamination 40 according to the concept of the invention.
Making reference to
In the perspective views shown in
Concretely speaking, when the rotor core 20 is attached with a precise fit onto the rotor shaft 10, the pressure areas PF of the uneven surface OF that protrude on the recognizable edges K and that are visible in
In order to create an advantageous interference fit, the mean diameter D of the contour 71 of the pentagon shown in
In the example, the additional configuration of a central recess 170 can be seen in the embodiment of
The Reuleaux triangle of the contour 171 is depicted in
In the present case, this results in a roundness deviation RA for the embodiment of
In an embodiment that can be seen in
The above-mentioned permanent magnets 39—supported by the formation of the core laminations 40, 40A, 40B—are also surrounded by the transfer-molding compound 30 on all sides.
The transfer-molding compound head 37 situated on the front face and shown in
The encoded placement of the core laminations 40 also assists the encoded attachment of a bearing and fan mount 33′, which is shown here in yet another modified form. This bearing and fan mount 33′ has a plurality of webs 36′ as well as at least one flat surface 38 that is oriented parallel to the longer section of the edge 89 of a receiving opening 80 for a permanent magnet 39. As a result, in an alternative to
The components, namely, the core lamination 40, the bearing and fan mount 33 as well as the carrier plate 230 and the printed circuit board 210 have encoding that is harmonized with each other. Thanks to a simple assembly of the individual components that makes use of the encoding, there is no need for laborious adjustment work in order to detect the position of the rotor 100 and to regulate the electric motor 1000.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2010 031 399.8 | Jul 2010 | DE | national |
