WO2016207023A1

WO2016207023A1 - Rotor for an electronically commutated electric motor and method for producing such a rotor

Info

Publication number: WO2016207023A1
Application number: PCT/EP2016/063589
Authority: WO
Inventors: Christoph Maier; Tobias Hokenmaier; Thomas Burkhardt
Original assignee: C. & E. Fein Gmbh
Priority date: 2015-06-25
Filing date: 2016-06-14
Publication date: 2016-12-29
Also published as: DE102015110267A1

Abstract

The invention relates to a rotor for an electronically commutated electric motor, comprising a rotor shaft (12) on which a rotor packet (14) with magnets is received. The rotor shaft (12) is equipped with at least one balancing ring (20, 22) which is connected to the rotor shaft (12) and the rotor packet (14) in a rotationally secured manner. A centering element (26) for centering with the rotor packet (14) is provided on the balancing ring (20, 22). The rotor packet (14) together with the balancing rings (20, 22) is preferably electrically insulated from the rotor shaft (12) by an electric insulation (24). The invention further relates to a method which is suitable for producing such a rotor (10).

Description

Rotor for an electronically commutated electric motor

and method for producing such

The invention relates to a rotor for an electronically commutated electric motor, with a rotor shaft, on which a rotor assembly is received with permanent magnets.

The invention further relates to a method for producing a rotor for a

electronically commutated electric motor.

In the manufacture of electronically commutated electric motors (hereinafter also

Called EC motors), the rotor, which has a rotor shaft and a rotor package received thereon with permanent magnets, can not be satisfactorily balanced in the usual way. In the permanent magnets and in the rotor core required for balancing depressions can not be introduced.

To avoid this problem, balancing rings of non-magnetic material are commonly used in the art, which are firmly connected to the rotor shaft and the rotor core and where the removal of mass, usually by introducing wells for balancing is possible.

If the EC motor is to be used not only for low voltage (battery operation), but also for mains operation (for example 1 10 or 230 V AC voltage), it is necessary to additionally insulate the rotor shaft. This can be achieved by injecting the rotor shaft with the rotor package applied.

The alignment of rotor core, rotor shaft and balancing rings in the spray device required for this purpose is complicated here. Here, the rotor core, the rotor shaft and the balancing rings must be precisely aligned in each case to allow the best possible concentricity even before the balancing process.

It therefore results in a rather complex structure and a complex production of the rotor.

Against this background, the invention has the object to provide a rotor for an electronically commutated electric motor with the simplest possible structure of high quality and also to provide a method for producing such a rotor, which works as simple and inexpensive.

With regard to the rotor, this object is achieved in a rotor according to the aforementioned type in that on the rotor shaft at least one balancing ring is arranged, which is connected against rotation with the rotor shaft and the rotor core and centered by means of at least one centering with the rotor core. The object of the invention is achieved in this way.

According to the invention, centering of the at least one balancing ring by means of the centering element on the rotor core ensures centering between the balancing ring and the rotor core. This makes it possible, in the case of insulation between the rotor assembly with balancing ring on the one hand and the rotor shaft on the other hand only to use a centering of the rotor shaft with respect to the Polpaket with the associated Auswuchttring.

This results in a higher precision in the production, since the production-related imbalance between the rotor shaft, Polpaket and Auswuchtring is reduced by the previously caused centering between Polpaket and Auswuchtring. As a result, overall there is a significantly lower primary imbalance than was the case with conventional rotors. In addition, the production is simplified.

Since the primary unbalance of the rotor is usually reduced, less corrective measures are required in balancing, so that the mass of the balancing ring can be reduced compared to conventional rotors. This results in an improved power of the EC motor.

According to a further embodiment of the invention, the centering element has a

Extension on the centering ring, which is enclosed by one end of the rotor core.

This extension may be formed, for example, as a hollow cylindrical extension.

By means of the extension, a centering can be effected directly on the rotor core, so as to ensure a uniform centering of the rotor core with respect to the rotor shaft.

According to a further embodiment of the invention, the centering element

Positive locking element, which is aligned with an associated counter-element on the rotor core. Here, the interlocking element may for example be formed as a centering nose, which is aligned with an associated recess. In this case, the centering nose can be provided either on the rotor core or on the balancing ring, wherein the respective associated counter-element is provided on the respective other part.

In this way, a rotationally fixed connection between the rotor core and balancing ring, as well as a centering can be ensured in a simple manner.

According to a further embodiment of the invention, the centering element and the

Rotor package with the rotor shaft by means of a positive connection over the molding compound secured against rotation.

This allows a simplified production and a permanent connection between

Rotor package and rotor shaft.

According to a further embodiment of the invention, two centering rings are provided, which are centered at both ends of the rotor assembly via a respective centering.

If the centering elements are used at both ends of the rotor stack, this results in an improved concentricity and a simplified production.

According to a further embodiment of the invention, the rotor core with the

at least one balancing ring kept electrically isolated on the rotor shaft.

Preferably, in this case the rotor core is connected to the at least one balancing ring via an electrically insulating injection-molded connection with the rotor shaft.

In this way, a simple and inexpensive production with high precision is possible even when using the rotor for network operation. The rotor is, as already mentioned above, preferably balanced, wherein

any imbalances are balanced by associated depression (s) in the at least one balancing ring.

Here, in addition to the rotor shaft, a fan be held, which is also balanced with the rotor.

In this way, an extremely precise concentricity is guaranteed.

With regard to the method, the object of the invention is further achieved by a method for producing a rotor for an electronically commutated electric motor with the following steps:

(a) providing a rotor shaft;

(b) providing a rotor package having recesses for receiving permanent magnets;

(c) applying at least one balancing ring with at least one centering element to an axial end of the rotor core;

(d) aligning the at least one centering element on the rotor core;

(e) joining the at least one centering element of the at least one balancing ring with the rotor core;

(F) placing the rotor package with the at least one balancing ring on the

Rotor shaft;

(g) connecting the rotor core to the rotor shaft to complete the rotor;

(h) clamping the rotor in a balancing machine;

(i) driving the rotor on the balancing machine for balancing;

(j) generating signals for specifying size and position of recess (s) on the at least one balancing ring;

(K) inserting recess (s) in the at least one balancing ring according to

Signals, if necessary.

In this way, the production of a rotor for an EC motor is achieved in a particularly simple manner. Since the at least one balancing ring is aligned with the at least one centering element at one axial end of the rotor core, this results in a significantly simplified production and accurate centering with respect to the rotor core.

According to a further embodiment of the invention in step (g) the following

Steps performed;

(gl) placing the rotor shaft with the balancing rings and the rotor package in a Umpresswerkzeug;

(g2) closing the Umpresswerkzeugs, whereby the rotor shaft is centered with the rotor core and the Auswuchtringen;

(g3) injection of electrically insulating potting compound in a cavity between

Rotor shaft and rotor package with balancing rings;

(g4) hardening of the potting compound in the Umpresswerkzeug at elevated temperature; (g5) removing the rotor from the Umpresswerkzeug;

(g6) cooling the rotor.

In this way, an electrical insulation of the rotor core with associated

Balancing rings relative to the rotor shaft can be ensured in a particularly simple and reliable manner. By the respective centering of the rotor core and the rotor shaft in the Umpresswerkzeug a particularly high precision and low UrUnwucht the rotor is achieved. As a result, the manufacturing process is considerably simplified, since only the rotor shaft and the rotor core with the balancing rings centered thereon must be inserted into the Umpresswerkzeug and thus no separate centering between balancing rings and rotor shaft or rotor core is necessary.

Malfunctions on the Umpresswerkzeug be reduced in this way. Further

the production is simplified in that only two parts, namely the rotor shaft and the rotor core with the balancing rings received thereon must be inserted into the Umpresswerkzeug, instead of previously four parts, as in the prior art. In addition, this ensures a significantly improved alignment between the rotor shaft, rotor core and Auswuchtringen, so that the primary imbalance after spraying the cavity with electrically insulating potting compound reduced in comparison to the prior art.

Also, there is a reduced need for later balancing on the

Balancing machine, which basically benefits the concentricity. In addition, the balancing rings can be carried out with a reduced mass, which reduces the total mass of the rotor and thus improves the power of the EC motor thus produced.

Furthermore, after the step (g), a fan wheel can be placed on the rotor shaft and thereby connected in a rotationally fixed manner and the subsequent steps (i) to (k) can be carried out with the fan wheel attached.

In this way, a balance of the fan is guaranteed in a single operation.

It is understood that the features of the invention mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the invention.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings. Show it:

Fig. 1 is a perspective view of a rotor according to the invention for an EC motor; Fig. 2 is a longitudinal section through the rotor of FIG. 1, wherein additionally a

Fan wheel is indicated on the rotor shaft, the cutting path is exactly through a fan blade;

FIG. 3 shows a perspective view of a balancing ring according to FIG. 1 in an enlarged representation; FIG.

4 shows an enlarged partial section of the rotor according to FIG. 2 in the region of one end of the rotor core with pressed-on balancing ring and underlying electrical insulation;

5 is a perspective view of the rotor package with pressed balancing rings at both ends, but before the introduction of the electrical insulation.

6 shows a perspective view of the rotor with a rotor core placed on the rotor shaft and balancing rings pressed in before the encapsulation in the crimping tool;

Fig. 7 is a schematic side view of a suitable Umpresswerkzeugs with two pressing halves;

8 shows a longitudinal section through the Umpresswerkzeug according to FIG. 7 and

Fig. 9 is a simplified schematic representation of a balancing machine for balancing the rotor.

1 and 2, an inventive rotor for an EC motor is shown and designated overall by the numeral 10.

According to FIG. 1, the rotor 10 has a rotor shaft 12, on which a rotor package designated as a whole with 14 with balancing rings 20, 22 pressed in at both ends and an underlying insulation 24 is received. The rotor core 14 has magnets in the form of permanent magnets 18.

In order to use the rotor 10 in the network operation, is an additional

electrical insulation 24 between the rotor core 14 with the balancing rings 20, 22 on both ends on the one hand and the rotor shaft 12 on the other hand required (see Fig .. 2).

In the sectional view of FIG. 2 is additionally a fan 25 on the

Rotor shaft 12 which is fixed by means of a press fit on the rotor shaft 12 immediately adjacent to the insulation 24.

The structure of the balancing rings 20, 22 is better apparent from the enlarged view of FIG. 3.

At each balancing ring 20 is a generally designated 26 centering provided on the rotor package 14 indicative end. The centering element 26 has a hollow cylindrical extension 30, as well as a plurality of positive locking elements 28 which are arranged distributed at equal angular intervals over the inner surface of the Auswuchtrings 20 and extend in the axial direction. It may be about depressions in the form of grooves. These interlocking elements 28 are associated with associated counter-elements 29 at the respective ends of the rotor core 14 (see FIG. 4).

During assembly, the balancing rings 20, 22 first at the two ends of the

Rotor packet 14 attached and aligned with their centering elements 28 with the associated counter-elements 29 of the rotor assembly 14. Subsequently, joining takes place in a suitable joining tool, so that the balancing rings 20, 22 engage with their extensions 30 respectively in the associated axial ends of the rotor assembly 14 and are held against rotation with the form-locking elements 28 to the associated counter-elements 29 and centered. This results in the rotor package 14 'according to FIG. 5 with balancing rings 20, 22 accommodated thereon. 7, an injection molding of the cavity 33 (see FIG. 6) between the rotor shaft 12 and the rotor core 14 with the balancing rings 20, 22 accommodated thereon takes place.

The Umpresswerkzeug 32 is shown in FIG. 7 of two mold halves, a lower mold half 34 and an associated upper mold half 36 which are movable relative to each other, as indicated by the double arrow 40 in Fig. 7.

At least on one mold half, preferably on the upper mold half 36 in the region of the parting line between the two mold halves 34, 36, a connection 38 is provided with a pressure line 39 for supplying potting compound under pressure, as indicated by the arrow 42.

FIG. 8 shows a longitudinal section through the two mold halves 34, 36. Provided in the lower mold half 34 is a recess 44 for receiving the rotor shaft 12 with the rotor stack 14 received thereon and a balancing ring 20. In the upper mold half 36 is a zugerdnete recess for the other end of the rotor shaft 12 with the other Auswuchtring 22 is provided. For centering and alignment of the rotor shaft 12 44 centerings 45, 46 are provided, for example, at both ends both in the lower mold half 34 and in the upper mold half 36, which has a precise position of the rotor shaft 12 in cooperation with the associated ends of the rotor shaft 12 ensure. For centering the rotor core 14 'with the balancing rings 20, 22 pressed therewith, corresponding centerings 47, 48 on the depression 44 are used, which ensure a precise position of the rotor core 14.

After closing the upper mold half 36 remains between the rotor core 14 with balancing rings 20, 22, a cavity 33 which is indicated in the perspective view of the rotor 14 "according to FIG. 6 with 33 and in Fig. 8 also with the numeral 33 is marked.

When inserting the rotor shaft 12 with it mounted rotor package 14 "as shown in FIG. 6 in the lower mold half 34 and a subsequent closing of the upper mold half 36th On the other hand, the rotor shaft 12 on the one hand and the rotor core 14 "on the other hand are precisely positioned and centered relative to one another by the corresponding centerings 45, 46 or 47, 48.

By an associated runner 49 in the upper mold half 36 is a

Distribution of the supplied via the terminal 38 potting compound under increased pressure and elevated temperature in the associated cavity 33 between the rotor shaft 12 on the one hand and rotor assembly 14 "with balancing rings 20, 22 taken on the other guaranteed.

After closing the Umpresswerkzeugs 32, the potting compound via the line 39 and the terminal 38 under elevated pressure (200 to 400 bar, preferably 300 bar) and at a Vergussmassentemperatur of e.g. 40 ° C fed to about 170 ° C heated mold. After the spraying process, which lasts only a few seconds (about 1 to 2 seconds), the curing process takes place under pressure and heat. After curing (takes about 90 seconds), the thus completed rotor 10 can be removed.

As potting compound, for example, serves a thermosetting plastic (here: an unsaturated polyester resin). After complete cooling of the rotor, the fan wheel 25 is preferably initially applied by a press fit immediately adjacent to the insulation 24 on the side of the first Auswuchttrings 20.

Subsequently, the rotor 10 is clamped on a balancing machine 50 approximately as shown in FIG. 9 and balanced.

For this purpose, the rotor 10 is placed on a receptacle 52. An apron 54 serves as burst protection. After briefly driving the rotor 10 by means of a controller 58 signals are displayed on an associated display 56, the position and size of corresponding balancing depressions 21 can be removed, which are to be introduced into the balancing rings 20 and 22, respectively, to ensure a complete balancing of the rotor 10 , In Fig. 1, such a balancing recess is exemplified by the numeral 21.

Claims

claims

1 . Rotor for an electronically commutated electric motor, having a rotor shaft (12) on which a rotor core (14) with magnets (18) is accommodated, characterized in that at least one balancing ring (20, 22) is arranged on the rotor shaft (12), which is connected against rotation with the rotor shaft (12) and the rotor core (14) and centered by means of at least one centering element (26) with the rotor core (14).

2. Rotor according to claim 1, characterized in that the centering element (26) has an extension (30) on the centering ring (20, 22) which is enclosed by one end of the rotor core (14).

3. Rotor according to claim 2, characterized in that the extension (27) as

hollow cylindrical extension (27) is formed.

4. Rotor according to claim 2 or 3, characterized in that the centering element (26) has a positive locking element (28) which is aligned with an associated counter-element on the rotor core (14).

5. Rotor according to claim 4, characterized in that the positive-locking element (28) is designed as a centering nose, which is aligned with an associated recess (29).

6. Rotor according to one of the preceding claims, characterized in that the centering element (26) and the rotor core (14) with the rotor shaft (12) by means of a positive connection via a molding compound are secured against rotation.

7. Rotor according to one of the preceding claims, characterized in that two centering rings (20, 22) are provided, which are centered at both ends of the rotor core (14) via a respective centering element (26).

8. Rotor according to one of the preceding claims, characterized in that the rotor core (14) with the at least one balancing ring (20, 22) is held electrically isolated on the rotor shaft (12).

9. Rotor according to claim 8, characterized in that the rotor core (14) with the at least one balancing ring (20, 22) via an electrically insulating injection-molded connection (24) with the rotor shaft (12) is connected.

10. Rotor according to one of the preceding claims, characterized in that the rotor (10) is balanced, with any imbalances by associated recess (s) (21) on at least one Auswuchtring (20, 22) are balanced.

1 1. Rotor according to one of the preceding claims, characterized in that further on the rotor shaft (12) a fan wheel (25) is held, which is balanced with the rotor (10).

12. Electronically commutated electric motor with a rotor (10) according to one of the preceding claims.

13. A method of manufacturing a rotor (10) for an electronically commutated electric motor comprising the steps of:

(a) providing a rotor shaft (12);

(b) providing a rotor core (14) with recesses for receiving permanent magnets (18);

(c) applying at least one balancing ring (20, 22) with at least one centering element (26) to an axial end of the rotor core (14);

(d) aligning the at least one centering element (26) on the rotor core (14);

(e) joining the at least one centering element (26) of the at least one balancing ring (20, 22) to the rotor core (14); (F) placing the rotor core (14) with the at least one balancing ring (20, 22) on the rotor shaft;

(g) connecting the rotor core (14) to the rotor shaft (12) to complete the rotor (10);

(h) gluing the permanent magnets (18) into the recesses of the rotor core (14);

(i) clamping the rotor (10) in a balancing machine (44);

(j) driving the rotor (10) on the balancing machine (44) for balancing;

(k) generating signals for specifying size and position of recess (s) (21) on the at least one balancing ring (20, 22);

(I) inserting recess (s) (21) into the at least one balancing ring (20, 22) according to the signals, if necessary.

14. The method according to claim 13, wherein in steps (c) to (e) two balancing rings (20, 22) each having at least one centering element (26) are used, which are respectively attached to the axial ends of the rotor core (14) to be aligned and pressed with the rotor assembly (14).

15. The method of claim 14, wherein in step (g) the following steps are performed;

(gl) placing the rotor shaft (12) with the balancing rings (20, 22) in a Umpresswerkzeug (32);

(g2) closing the Umpresswerkzeugs (32), whereby the rotor shaft (12) with the rotor core (14) and the Auswuchtringen (20, 22) is centered;

(g3) injecting electrically insulating potting compound (24) into a cavity (33) between rotor shaft (12) and rotor core (14) with balancing rings (20, 22);

(g4) hardening of the potting compound (24) in the Umpresswerkzeug (32) at elevated temperature;

(g5) removing the rotor (10) from the Umpresswerkzeug (32);

(g6) cooling the rotor (10).

16. The method according to any one of claims 13 to 15, wherein after step (g) or (h) further on the rotor shaft (12) a fan wheel (25) is placed and rotatably connected thereto and the subsequent steps (i) to ( I) be performed with attached fan (25).