WO2021185490A1

WO2021185490A1 - Rotor of an electric motor

Info

Publication number: WO2021185490A1
Application number: PCT/EP2021/051146
Authority: WO
Inventors: Antonio Menonna
Original assignee: Mahle International Gmbh
Priority date: 2020-03-18
Filing date: 2021-01-20
Publication date: 2021-09-23
Also published as: DE102020203483A1

Abstract

The invention relates to a rotor (1) of an electric motor (2). It is essential to the invention here - that laminated cores (4) are provided which are arranged with a clearance fit on a rotor shaft (3) of the rotor (1), and - that a first and a second clamping washer (5, 6) are provided which are arranged on the rotor shaft (3) and clamp the laminated cores (4) between them in the axial direction (7) and fix them as a result. An inexpensive rotor (1) can thereby be provided.

Description

Rotor of an electric motor

The present invention relates to a rotor of an electric motor according to the preamble of claim 1. The invention also relates to an electric motor with such a rotor.

Laminated cores, which form an iron core for coils, are usually arranged on the rotors of electric motors. Such laminated cores are usually joined on the rotor with an interference fit with high overlap in order to be able to ensure a safe and reliable tight fit. The disadvantage here, however, is that the laminated cores can be deformed, which, for example, can be damaged in their coating. Alternatively, a thermal joint fit of the laminated cores on the rotor shaft is also conceivable, but this is only possible to a limited extent in terms of manufacturing technology due to the low temperature resistance of the laminated cores and their coating.

The present invention is therefore concerned with the problem of specifying an improved or at least one alternative embodiment for a Ro tor of an electric motor of the generic type, which especially the disadvantages known from the prior art with regard to a fixation of the Blechpake te on a rotor shaft of the rotor avoids.

This problem is solved according to the invention by the subject matter of the independent claim 1. Advantageous embodiments are the subject of the dependent claims.

The present invention is based on the general idea that the individual laminated cores of a rotor of an electric motor are not directly on a rotor shaft of the rotor to be fixed, for example via a thermal joint fit or a press fit, but with a clearance fit, that is to say with a radial clearance, to be arranged on the rotor shaft and to be fixed via two clamping disks acting in the axial direction. For this purpose, according to the invention, a first and a second clamping disk are provided, which are arranged on the rotor shaft and clamp the laminated cores between them in the axial direction and thereby fix them.

The great advantage of such a design is, for example, that the rotor shaft itself no longer has to be made as stable and therefore heavy as would be required, for example, with a press fit of the laminated cores on the rotor shaft or a thermal joint fit, which not only results in a reduction in weight , but also a cost reduction can be achieved. As a result of the thinner rotor shaft that can be used and the axial fixation of the laminated cores, the inner diameter of the laminated cores becomes inoperative and can therefore be made significantly larger. This creates a cavity between the thin rotor shaft and the large inner diameter of the laminated core, which reduces weight, material and thus costs. This additional cavity can be used for direct cooling of the laminated cores to whoever. Furthermore, since the laminated cores no longer sit directly on the rotor shaft, it can also be produced more cost-effectively, since in particular post-processing, for example grinding, of the same on an outer surface can be dispensed with. In addition, such a rotor according to the invention also offers additional space for cooling, as a result of which the performance of the electric motor can be increased.

In an advantageous development of the solution according to the invention, the first clamping disk is firmly fixed in the axial direction on the rotor shaft, while the second clamping disk is arranged axially movably on the rotor shaft and is fixed in the axial direction via a fixation element. This enables a comparatively simple assembly of the sheet metal stacks and, at the same time, a comparatively simple fixation. tion of the same possible. A cotter pin, pin or nut inserted through the Ro gate shaft can serve as a fixing element. Alternatively, of course, a final pressing (longitudinal press fit), shrinking (cross press fit), gluing, welding or soldering of the first and / or the second clamping disk to the rotor shaft is also conceivable.

In a further advantageous embodiment of the solution according to the invention, bearing areas formed in one piece with the tubular shaft are provided on the longitudinal end side. Reliable, smooth storage of the rotor shaft in an electric motor is possible via such bearing areas, with the fact that the bearing areas are lumpy with the rotor shaft, so mounting the bearing areas on the rotor shaft can be dispensed with, making it more cost-effective to manufacture.

In an alternative embodiment of the rotor according to the invention, the rotor shaft is designed as a built-up shaft, with a hollow shaft as a center piece, and the first and second clamping disks, which clamp the laminated cores between them and thereby fix them. In such an embodiment, it is possible to make the hollow shaft of the rotor shaft, which serves as the center piece, thinner and therefore also in particular lighter, whereby both resource conservation and weight reduction can be achieved. In such a rotor, too, the individual laminated cores are clamped or axially braced between the axially spaced apart clamping disks, with the hollow shaft also being arranged between the two clamping disks.

A shaft constructed in this way can be joined as follows, for example: First, the hollow shaft is inserted into a corresponding central receptacle of the first clamping disk and fixed, for example via a screw connection, an adhesive connection, a soldered connection or a welded connection. The individual laminated cores are then arranged in a circle around the hollow shaft and then the second clamping disk with a central receiving opening is placed on the free end of the hollow shaft, the laminated cores being axially braced between the two clamping disks. The second clamping disk can also be fixed to the hollow shaft, for example, by screwing it on or some other, in particular non-detachable, connection.

The hollow shaft is expediently designed as a drawn tube that is not machined on its surface. In the construction form described in the previous paragraph, there is the great advantage that the hollow shaft used as the center piece has no radial contact with the laminated core and therefore does not have to be machined, for example ground, on its surface. As a result, the hollow shaft and, moreover, the entire rotor can be manufactured much more cheaply. Of course, the rotor shaft can also be designed as a drawn tube that has not been reworked on its surface, regardless of the selected embodiment, even with a rotor shaft as a solid shaft, there is no contact between the laminated cores and the rotor shaft, so that the rotor shaft Regardless of their embodiment, their outer surface does not have to be reworked, for example ground, as a result of which a significantly more cost-effective production thereof is possible.

If one considers the rotor shaft designed as a built-up shaft in the previous paragraphs, bearing areas can also be arranged at their longitudinal ends, which are designed as separate components and are connected to the hollow shaft. are bound. Alternatively, it is of course also conceivable that the bearing areas are connected to the respective adjacent clamping disc and have no direct connection to the hollow shaft. In this case, it is possible to vorzufer term the clamping disks together with the respective associated storage area and, in particular, to preprocess and / or coat the storage areas, thereby enabling easy storage.

In a further advantageous embodiment of the solution according to the invention, at least one laminated core is connected to at least one clamping disk via a form-fitting connection. Such a form-fit connection can be implemented, for example, by a corresponding recess on / in the clamping disk, in which the laminated core engages at least partially. Of course, a reverse embodiment is also conceivable, with both embodiments having in common that the individual laminated cores are reliably held on the rotor by the form-fitting connection.

In a further advantageous embodiment of the solution according to the invention, at least one clamping disk is designed as a balancing disk to compensate for a possible imbalance. This makes it possible to compensate for any unbalances in the rotor that may be present in a comparatively simple manner by means of a corresponding arrangement in terms of the angular position of the respective clamping disk. Of course, weights are also conceivable, which are attached to the respective clamping disk in accordance with the determined imbalance to compensate for the same. The clamping disc can for example be made of metal, in particular as a sheet metal part, or made of plastic and thereby be manufactured not only of high quality, but also inexpensively.

The present invention is further based on the general idea of designing an electric motor with a rotor described in the previous paragraphs. equip, whereby the advantages mentioned and described above can be transferred to the electric motor. Specifically, these are a cost reduction due to a lower production cost of the rotor shaft and, for example, a weight reduction and / or the creation of an additional space for a cooling option.

Further important features and advantages of the invention emerge from the subclaims Un, from the drawings and from the associated description of the figures based on the drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or on their own, without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, with the same reference numerals referring to the same or similar or functionally identical components.

They show, in each case schematically,

Fig. 1 shows a first possible embodiment of a Ro tor according to the invention,

Fig. 2 shows another possible embodiment of the Ro tor according to the invention, Fig. 3 is a sectional view through a further embodiment of the inventive rotor.

According to FIGS. 1 to 3, an inventive rotor 1 of an electric motor 2 has a rotor shaft 3 on which laminated cores 4 are arranged with a clearance fit. In this case, a clearance fit can mean that the laminated cores 4 are at a radial distance from the rotor shaft 3; H. do not touch them in the radial direction. The laminated cores 4 form iron cores around which, for example, copper wires are wound as coils. The rotor shaft 3 can be designed as a solid shaft or as a flea shaft.

For reliable fixation of the laminated cores 4 on the rotor shaft 3, according to the invention, they are no longer fixed on the rotor shaft 3 as before, for example via a thermal joint or a press fit, but a first clamping disk 5 and a second clamping disk 6 are provided, which are attached to the Rotor shaft 3 are arranged and clamp the laminated cores 4 in the axial direction 7 between them and thereby fix them.

According to FIG. 1, for example, the first clamping disk 5 can be fixedly fixed in the axial direction 7 on the rotor shaft 3, while the second clamping disk 6 is initially arranged to be axially movable on the rotor shaft 3 for mounting the laminated cores 4 and only finally to clamp the laminated cores 4 is fixed via a fixing element 8. Such a fixing element 8 can be, for example, a split pin, a nut or another fixing element. In purely theoretical terms, it is also conceivable that, in the embodiment according to FIG. 1, the first and second clamping disks 5, 6 are each firmly connected to an outer jacket surface of the rotor shaft 3, for example glued, welded or soldered to it. Regardless of the selected embodiment, it is common to all Ausführungsfor men that a direct connection of the laminated cores 4 with the rotor shaft le 3 is not present, which means that, in particular, complete reworking of the outer circumferential surface of the rotor shaft 3, for example by grinding, can be omitted, so that it can be manufactured significantly more cost-effectively.

Theoretically, the first clamping disk 5 can also be designed as a radial collar on the rotor shaft 3, in particular even in one piece with it. In this case, the radial collar would be designed as an annular shoulder and can have a smaller outer diameter than the opposite second clamping disk 6.

On the longitudinal end side of the rotor shaft 3, for example, bearing areas 9 can be provided, which according to FIG. The bearing areas 9 can, however, also be formed separately, in particular they can also be an integral part of one of the clamping disks 5, 6. In the case of a hollow shaft 10, the bearing areas 9 can also be designed as inner plugs and be pressed into them.

The rotor shaft 3 can of course also have a different, for example a smaller, diameter in the bearing areas 9 than in a central area. Alternatively, it is also conceivable that the rotor shaft 3 is designed as a built-up shaft, as shown in FIG. 3, with a hollow shaft 10 as a center piece, and the first and second clamping disks 5, 6, which clamp the laminated cores 4 between them and thereby fix it. The hollow shaft 10 can be designed, for example, as a drawn tube that has not been post-treated on its Oberflä surface, whereby it can be manufactured inexpensively. Due to the embodiment as a hollow shaft, which can theoretically also be implemented in the rotor shaft 3 shown in accordance with FIG. 1 or 2, a weight reduction can also be achieved, as well as a material saving, whereby a weight saving and a cost reduction can be achieved.

Looking further at FIG. 3, it can be seen that the rotor shaft 3, which is designed as a hollow shaft 10, has a significantly smaller diameter in the central area, whereby a greater distance from the rotor shaft 3 or to the hollow shaft 10 is effected, whereby the cooling can be improved.

Looking at the embodiment of the rotor 1 according to the invention according to FIG. 3, bearing areas 9 are also arranged on this longitudinal end, which are designed as separate components and connected to the hollow shaft 10, for example glued, welded or soldered. The bearing areas 9 can be part of the first or second clamping disk 5, 6, or they can represent components formed separately from them. The hollow shaft 10 can - as shown in Fig. 3 - be joined on the inside with the first and second clamping disc 5, 6 or, alternatively, on the outside. It is also conceivable that the hollow shaft 10 is joined on the inside with the first clamping disc 5 and on the outside with the second clamping disc 6, or vice versa.

If one looks at the rotor 1 according to FIG. 3 in comparison to the rotor 1 according to FIG. 1, it can be seen that a radial play between the Blechpa keten 4 and the rotor shaft 3 is significantly larger in the rotor 1 according to FIG can be created for an additional cooling option.

In order to be able to achieve the most reliable connection of the laminated cores 4 with the clamping disks 5, 6, it can also be provided that at least one laminated core 4 with at least one clamping washer 5, 6 via a shaped Final connection 11 (as indicated in Figure 3) is connected. Via such a form-fit connection 11, the laminated cores 4 are fixed to the respective clamping disks 5, 6 not only via an axial preload, that is to say in a non-positive manner, but also in a positive-fit manner. For example, an associated recess 12 can be provided in the respective clamping disk 5, 6, according to FIG. Preferably, the recess 12 does not extend radially all the way to the outside of the respective clamping disk 5, 6, here the clamping disk 6, whereby an outer collar area 14 remains, which holds the laminated core 4 belonging to each against the centrifugal force. In purely theoretical terms, the recesses 12 or extensions 13 of this type can of course also be designed differently, as is shown, for example, in the case of the clamping disk 5 according to FIG. Additionally or alternatively, it is also conceivable that a recess 12 is arranged on a laminated core 4 and a corresponding extension 13 is arranged on an adjacent laminated core 4, the extension 13 engaging positively in the recess 12 and thereby creating a positive connection 11 between two adjacent laminated cores 4 forms (see. Fig. 2). All form-fit connections 11 have in common that a fixation of the laminated stacks 4 via the form-fit connections 11 reliably holds the laminated stacks 4, in particular with respect to the centrifugal forces that occur during operation of the rotor 1.

At one longitudinal end of the rotor shaft 3, an outer polygon 15 is arranged, via which a torque transmission, that is, a drive of a unit not shown GE is made possible. The polygonal socket 15 is usually inductively hardened, which is why, for example, the left bearing area 9 can be designed as a component of the first clamping disk 5, while the right bearing area 9 is separate from the second clamping disk 6 and can be hardened as a result. The storage areas 9 do not have to be hardened. In a further advantageous embodiment of the solution according to the invention, at least one clamping disk 5, 6 can be designed as a balancing disk, whereby unbalances can be compensated for by such a balancing disk or the clamping disk 5, 6. This means that additional balancing weights can be dispensed with.

In general, the clamping disks 5, 6 can be made of plastic or metal, for example as a sheet metal part, in particular if they are to have a recess 12 for a form-fitting connection 11 with the respective Blechpa ket 4.

With the rotor 1 according to the invention and thus also with the electric motor 2 according to the invention, a significant reduction in costs in the manufacture of the rotor 1 can be achieved, since in particular a full-surface reworking device, for example grinding, of the outer circumferential surface can be omitted because the laminated cores 4 are not, as hitherto, are connected to the rotor shaft 3 via a thermal joint connection or a press-fit connection, but are only held between two axially adjacent clamping disks 5, 6 via an axial preload. By designing the rotor shaft 3 at least partially as a hollow shaft 10, a weight reduction can also be achieved, which is of great advantage in vehicle construction in particular. Such a hollow shaft 10 can be reduced in diameter, creating an additional space for cooling, d. H. an annular space between the outer circumferential surface of the hollow shaft 10 and an inner surface of the laminated cores 4.

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Claims

Expectations

1. Rotor (1) of an electric motor (2) characterized in that

- that laminated cores (4) are provided which are arranged with a clearance fit on a rotor shaft (3) of the rotor (1),

- That a first and a second clamping disk (5, 6) are provided, which are arranged on the rotor shaft (3) and clamp the laminated cores (4) between them in the axial direction (7) and thereby fix them.

2. Rotor according to claim 1, characterized in that the first clamping disc (5) in the axial direction (7) is fixedly fixed on the Rotorwel le (3), while the second clamping disc (6) is arranged and axially movable on the rotor shaft (3) is fixed via a fixing element (8) in the Axialrich device.

3. Rotor according to claim 1 or 2, characterized in that

- That one of the clamping disks (5, 6) is designed as a radial collar on the rotor shaft (3) and in particular in one piece with it, and / or

- That the longitudinal end of the rotor shaft (3) is provided in one piece with this ausgebil Dete bearing areas (9).

4. Rotor according to claim 1, characterized in that that the rotor shaft (3) is designed as a built shaft, with a hollow shaft (10) as a center piece, the first and second clamping washer (5, 6), which clamp the laminated core (4) between them and thereby fix them.

5. Rotor according to claim 4, characterized in that the hollow shaft (10) is designed as a drawn tube that has not been reworked on its surface.

6. Rotor according to claim 4 or 5, characterized in that the longitudinal end of the rotor shaft (3) bearing areas (9) are arranged, which are designed as separate components and connected to the hollow shaft (10) or the associated clamping disc (5, 6).

7. Rotor according to one of the preceding claims, characterized in that at least one laminated core (4) is connected to at least one clamping disc (5, 6) via a form-fitting connection (11).

8. Rotor according to one of the preceding claims, characterized in that

- That a recess (12) is arranged in at least one clamping disc (5, 6) and an associated extension (13) is arranged on an associated laminated core (4), or vice versa, the extension (13) positively engaging in the recess (12) intervenes, and / or

- That a recess (12) is arranged on a laminated core (4) and an associated extension (13) is arranged on an adjacent laminated core (4) are, wherein the extension (13) engages positively in the recess (12).

9. Rotor according to one of the preceding claims, characterized in that at least one clamping disc (5, 6) is designed as a balancing disc to compensate for a possible imbalance.

10. Electric motor (2) with a rotor (1) according to one of the preceding claims.

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