Annular module and method for constructing motor of electric machine, rotor for electric machine, and electric machine

Abstract

The invention relates to an annular module (142) for constructing a rotor (14) of an electric machine (10), comprising an annular body with a circular central through-hole, the wall of which has a contact surface (143) surrounding the central through-hole over the entire circumference for retracting the annular module (142) onto a rotor shaft (16). The invention is characterized in that the joining surface (143) is interrupted in the axial direction by a groove (144) extending mainly in the circumferential direction.

Description

TECHNICAL FIELD

[0001] The invention relates to an annular module for constructing a rotor of an electrical machine, comprising an annular body with a circular central bore, the wall of which has an engagement surface which circumferentially surrounds the central bore for shrinking the annular module onto a rotor shaft.

[0002] The invention also relates to a method for constructing a rotor of an electrical machine, comprising the following steps:

[0003] - providing an annular module, comprising an annular body with a circular central bore, the wall of which has an engagement surface which circumferentially surrounds the central bore,

[0004] - providing a rotor shaft,

[0005] - establishing a temperature difference between the rotor shaft and the annular module, so that the annular module is hotter than the rotor shaft in the region of its engagement surface,

[0006] - pushing the annular module onto the rotor shaft, so that an axial overlap is produced between the rotor shaft and the engagement surface,

[0007] - eliminating the temperature difference, so that the rotor shaft and the annular module are force-fittingly joined to one another.

[0008] The invention also relates to a rotor for an electrical machine obtained by means of such a method and to a corresponding electrical machine. BACKGROUND

[0009] Annular modules, rotors and electrical machines of this type are known from document US 11,6325,024 B2 and from document JP 2002152999 A2. Methods of this type are also known from document JP 2002152999 A2.

[0010] Electrical machines which are constructed as so-called internal rotors are known to comprise a stator which is fixed to a base and a rotor which is rotatably supported radially within the stator. Here, in particular the frame of a motor vehicle can serve as the base, the electrical machine being used as a traction motor there. It is known here for the stator to be provided with a plurality of electrical windings, while the rotor is constructed as a so-called lamination core or as an assembly of a plurality of so-called lamination core modules (in the following collectively referred to as lamination core assembly) and is equipped with a permanent magnet assembly. In order to be able to transmit the torque which is generated by the electromagnetic interaction between the rotor and the stator, the rotor is fixed against rotation on a coaxial rotor shaft, at which the torque can be intercepted, for example, by means of a transmission. In addition to the lamination core assembly itself, the rotor shaft typically additionally carries so-called end plates axially on both sides of the lamination core assembly, which can serve, for example, as balance plates, star plates or pressure rings. Not only such end plates but also the lamination core itself or each lamination core module are to be covered by the term "annular module" here.

[0011] Especially for electric machines of very high power, a high-stable joining of the ring module to the rotor shaft is required. A pure form-fit connection is often not sufficient. The so-called shrinkage process known in principle proves to be suitable for the joining. Here, a temperature difference is established between the ring module and the rotor shaft, wherein, in particular, the ring module is hotter than the rotor shaft at least in the region of its joining face. Accordingly, the ring module, compared to the rotor shaft, experiences a greater thermal expansion, so that its joining face, that is to say the inner wall portion of its central bore, is relatively enlarged compared to the rotor shaft. If the fit dimensions are set appropriately, the ring module can be plugged onto the rotor shaft in this state largely force-free (herein also to be understood as the insertion of the rotor shaft into the ring module). With equalization of the temperature difference, the central bore of the ring module only shrinks or the rotor shaft expands, so that the two components are joined to one another force-fittingly. In the document JP 2002152999 A2 already mentioned at the beginning, such a shrinkage of an end plate onto a rotor shaft is described. The person skilled in the art understands that the mentioned temperature difference can be obtained not only by heating of the ring module, but also by cooling of the shaft (correspondingly relative to the same initial temperature, for example room temperature).

[0012] A problem corresponding to the described shrinkage is that a slight deviation from the ideal process parameters can already lead to a loss of the theoretically force-free pushing on of the ring module. This can occur in particular if the joining face of the ring module and the corresponding face of the rotor shaft are not precisely (hollow) cylindrical. In order to improve the torsional safety, for example, deviations from the pure cylindrical symmetry can be provided. In such a case, a minimum deviation from the optimum relative orientation can already be sufficient for debris to be produced upon pushing on. If this is not removed by means of a complex cleaning process, such dirt can cause short circuits and / or reach the air gap between rotor and stator with reduced performance during operation of the electric machine. SUMMARY

[0013] It is an object of the present application to provide a ring module of this type, a rotor for an electric machine, a manufacturing method therefor and an improved electric machine as such using the arch, which also has an improved operational safety without complex cleaning, in particular because less or no dirt accumulates upon shrinkage of the ring module onto the rotor shaft.

[0014] This object is achieved according to the present application in that the joining face is interrupted in the axial direction by a groove which extends predominantly in the circumferential direction.

[0015] This object is furthermore achieved according to the present application in that the ring module is a ring module according to the present application and that the debris which accumulates upon pushing on of the ring module onto the rotor shaft is enclosed in a cavity which is formed jointly by the groove and the rotor shaft.

[0016] The correspondingly produced rotor and the correspondingly designed electric machine are subject matter of the present application.

[0017] The preferred embodiments of the invention are described in the content of the specification.

[0018] The basic idea of the invention is to equip the annular module in the region of its joint face with at least one debris trap chamber in which the debris that accumulates upon shrinkage is continuously enclosed, so that such dirt cannot reach points that would cause damage to the electric machine upon operation. According to the invention, such a debris trap chamber is formed by one or more grooves that are introduced into the joint face and that thus divide the joint face in axial sections. Such grooves, which open to the radially inside in the insulating annular module, are closed in the jointed state by the outer wall of the rotor shaft, so that the dirt that is in them can no longer be pressed outwards.

[0019] In an embodiment that can be particularly simply implemented, the joint face is interrupted by a groove that surrounds the centre whole. Here, a (self-closing) annular groove or a helical groove can be involved. Here, the position of the groove can be largely freely chosen. There can be, in particular, identical or different axial sections of the joint face flanking the groove or between the individual helical return loops. The specific positioning can be chosen in individual cases, in particular, in view of the local characteristics of the chip accumulation.

[0020] It is also conceivable to provide a plurality of grooves that interrupt the joint face, spaced apart from one another in axial direction. Here, too, the size of the joint sections flanking the grooves or between the individual grooves can be largely freely chosen, in particular, to be identical or different. The groove depths of the different grooves can be identical or different.

[0021] In the case of a plurality of grooves, these can correspondingly surround the centre whole whole. However, embodiments are also conceivable in which the grooves correspondingly only incompletely surround the centre whole and are arranged in a circumferential manner offset from one another. It proves to be particularly advantageous here that the grooves complement one another in circumferential direction in such a way that they together form an axial interruption of the joint face that is whole in circumferential direction. In this way, no azimuthal gap between the azimuthally defined grooves is produced through which the debris that is produced upon jointing can slide through and not be continuously enclosed in the debris trap chamber. Said mutual complementing of the grooves in circumferential direction can be precisely implemented, either by the grooves being arranged on top of one another in circumferential direction.

[0022] In a particular refinement of the application, the axial end sections of the joint face are formed by an annular insert in the end and radially inwardly open pocket of the wall portion to the central bore. Preferably, the annular insert is composed of a particularly hardened material. Its axially inner surface preferably forms the axially outer groove wall of the debris trap groove according to the application. A particular advantage of such an annular insert composed of a hardened material is that all debris that accumulates in the region of the joint face upon shrinkage is trapped in the debris trap according to the application, but no additional debris accumulates in the axial end sections of the joint face due to the particular material hardness (for which there is no longer a debris trap in the axial end sections of the joint face and which can thus reach the motor chamber as dirt). BRIEF DESCRIPTION OF DRAWINGS

[0023] Further features and advantages of the present application will become apparent from the following detailed description and drawings.

[0024] wherein:

[0025] Figure 1 a schematic diagram of an electric machine according to the application is shown,

[0026] Figure 2 a partial illustration of a first embodiment of a rotor end plate according to the application is shown,

[0027] Figure 3 a partial illustration of a second embodiment of a rotor end plate according to the application is shown,

[0028] Figure 4 a partial illustration of a third embodiment of a rotor end plate according to the application is shown,

[0029] Figure 5 a partial illustration of a fourth embodiment of a rotor end plate according to the application is shown,

[0030] Figure 6 a partial illustration of a fifth embodiment of a rotor end plate according to the application is shown,

[0031] Figure 7 a partial illustration of a sixth embodiment of a rotor end plate according to the application is shown, and

[0032] Figure 8 a partial illustration of a seventh embodiment of a rotor end plate according to the application is shown. DETAILED DESCRIPTION

[0033] Like reference numerals in the figures indicate like or similar elements.

[0034] Figure 1A sectional view of an electric machine 10 according to the application is shown in an extremely diagrammatic illustration. It has a stator 12 which is fixed at a base, wherein the "base" at which the stator is to be fixed can be, for example, the frame of a motor vehicle. Radially within the stator 12 there is arranged a rotor 14 which is fixed in a torque-proof and axially fixed manner on a rotor shaft 16. In the embodiment shown, the rotor 14 comprises a lamination core assembly 141 which here consists of a plurality of, in particular three, lamination core modules, which are flanked on both sides in the axial direction by a respective end plate 142. In the embodiment shown, the end plates 142 are configured as pressure plates and serve as a support for bolts 18 which axially penetrate the rotor 14 and press its component parts together in the axial direction.

[0035] The rotor 14 is joined to the rotor shaft 16 by shrinkage, wherein the joining face 143 of the rotor 14 has a slot 144 in the region of the lamination core assembly 141 and also in the region of the end plate 142, which axially interrupts the joining face 143 or divides it into different axial sections.

[0036] Figures 2 to 8 Different design variants of the slot(s) 144 which divide or rather segment the joining face 143 are shown by way of example with different end plates 142.

[0037] In the embodiment shown in Figure 2 there is provided only one slot 144. This is configured as an annular slot which completely surrounds the central bore of the end plate 142. The annular slot shown is slightly offset from the axial centre of the joining face 143, so that it is divided into different-sized axial sections. However, embodiments in which the individual sections or axial sections of the joining face 143 are of equal size are also conceivable.

[0038] In the embodiment shown in Figure 3 there are provided two axially spaced annular slots which completely surround the end plate 142, which in particular divide the joining face 143 into three equally sized axial sections. However, embodiments in which more than two slots 144 are provided and / or in which the joining face 143 is divided into differently sized axial sections are also conceivable.

[0039] In contrast to the embodiments shown in Figure 2 and Figure 3 in which the slots 144 have the same depth respectively, Figure 4 an embodiment is shown which, like Figure 3 has two annular slots 144 which completely surround the end plate 142, wherein the slots 144 have different slot depths, however.

[0040] Figure 5 An embodiment is shown in which, like Figure 2 only one slot 144 is provided, which is designed however in a helical manner and surrounds the central bore of the end plate 142 in multiple turns.

[0041] In contrast, Figure 6 and Figure 7 The corresponding embodiment shows multiple slots 144 that only partially surround the central perforation of the end plate 142. In both cases, the angular segments spanned by each slot 144 supplement the interruption of the central perforation of the end plate 142 that generally produces a mating surface 143. This supplementation is in Figure 6 In its implementation, it is nearly precise, meaning that a slot 144 ends precisely at the angle at which the adjacent slot 144 begins. Figure 5 In the embodiment, adjacent slots 144 obviously overlap each other. However, it is also possible to consider an embodiment in which these slots do not complement each other to form a complete circle, that is, to have azimuth gaps, and an embodiment in which incomplete slots 144 complement each other to form multiple complete circles.

[0042] at last, Figure 8 A particular embodiment is shown in which the axial end section of the mating surface (in) Figure 8 The right side of the middle section is formed by an annular insert 145 made of hardened material, which simultaneously forms (in the middle right section) Figure 8 The only implementation of this type of groove is the axial outer groove wall of groove 144.

[0043] Of course, the embodiments discussed in the specific description and shown in the figures are merely illustrative examples of the invention. A wide range of variations are possible based on this disclosure, as will be apparent to those skilled in the art. Those skilled in the art will particularly understand that the illustrated design of slot 144 can be combined in many arbitrary ways. Those skilled in the art will also understand that the slot shape described in the context of end plate 142 can also be adapted in the same or similar manner to other components of rotor 14, particularly to its laminated core assembly 141, or (if any) to its individual laminated core modules.

[0044] List of reference signs

[0045] 10 motors

[0046] 12 stators

[0047] 14 Rotors

[0048] 141 Laminated Iron Core Assembly

[0049] 142 Ring Module / End Panel

[0050] 143 Joint surface

[0051] 144 slots

[0052] 145 Insertion

[0053] 16 Rotor shafts

[0054] 18 peg.

Claims

1. Ring module (142) for building a rotor (14) of an electric machine (10), comprising a ring body with a circular central bore, the wall of which has an engagement face (143) that circumferentially surrounds the central bore for shrinking the ring module (142) onto a rotor shaft (16), characterized in that the engagement face (143) is interrupted in the axial direction by grooves (144) that extend predominantly in the circumferential direction.

2. The ring module (142) according to claim 1, characterized in that the engagement face (143) is interrupted by grooves (144) that circumferentially surround the central bore.

3. The ring module (142) according to claim 2, characterized in that the grooves (144) are configured as annular grooves.

4. The ring module (142) according to claim 2, characterized in that the grooves (144) are configured helically.

5. Ring module (142) according to any of the preceding claims, characterized in that the engagement face (143) is interrupted by a plurality of grooves (144) that are axially spaced apart from one another.

6. The ring module (142) according to claim 5, characterized in that the grooves (144) each only incompletely surround the central bore and are arranged circumferentially offset from one another.

7. The ring module (142) according to claim 6, characterized in that the grooves (144) complement one another in the circumferential direction such that they together form an axial interruption of the entire circumference of the engagement face (143).

8. The ring module (142) according to claim 7, characterized in that the grooves (144) overlap one another in the circumferential direction.

9. Ring module (142) according to any of the preceding claims, characterized in that axial end sections of the engagement face (143) are formed by annular inserts (145) in end- and radially inwardly open pockets of the wall of the central bore.

10. Method for building a rotor (14) of an electric machine (10), comprising the following steps: - providing a ring module (142), which comprises a ring body with a circular central bore, the wall of which has an engagement face (143) that circumferentially surrounds the central bore, - providing a rotor shaft (16), - establishing a temperature difference between the rotor shaft (16) and the ring module (142) such that the ring module (142) is hotter than the rotor shaft (16) in the region of its engagement face (143), - pushing the ring module (142) onto the rotor shaft (16) such that an axial overlap is produced between the rotor shaft (16) and the engagement face (143), - eliminating the temperature difference, thereby force-fittingly engaging the rotor shaft (16) and the ring module (142) with one another, characterized in that the ring module (142) is a ring module (142) according to any one of the preceding claims, and that debris that accumulates when the ring module (142) is pushed onto the rotor shaft (16) is enclosed in a cavity that is formed jointly by the grooves (144) and the rotor shaft (16).

11. Rotor (14) for an electric machine (10), which is obtained by the method according to claim 10.

12. An electric machine (10) comprising a stator (12) and a rotor (14) rotatably movably supported in the stator (12) in the radial direction, the rotor comprising at least one annular module (142) joined, in particular shrunk, to a rotor shaft (16), characterized in that the ring module (142) is a ring module (142) according to any one of claims 1 to 9.

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