EP3549245A1

EP3549245A1 - Rotor for an lspm electric motor

Info

Publication number: EP3549245A1
Application number: EP17781078.5A
Authority: EP
Inventors: Werner Müller; Friedrich Schaffert; Otmar HÜGEL; Michael Eccarius; Jens Krotsch
Original assignee: Ebm Papst Mulfingen GmbH and Co KG
Current assignee: Ebm Papst Mulfingen GmbH and Co KG
Priority date: 2016-11-30
Filing date: 2017-10-04
Publication date: 2019-10-09
Also published as: DE102016123064A1; WO2018099632A1; CN206498267U

Abstract

The invention relates to a rotor (1) for an electric motor, the rotor (1) comprising a laminated core (2) made of a stack of laminations (20) insulated from each other, and a plurality of permanent magnets (3) are introduced into the laminated core (2). The laminated core (2) is surrounded by a metal rotor casting (4) and/or partially filled therewith. The invention is characterised in that the laminated core represents 40-70 mass %, the permanent magnets (3) represent 10-50 mass %, and the rotor casting (4) represents 8-25 mass % of the total mass of 100% shared between the laminated core (2), the permanent magnets (3) and the rotor casting (4).

Description

Rotor for an internal rotor electric motor

Description:

The invention relates to a rotor for an internal rotor electric motor.

Rotors for electric motors are known in various embodiments for synchronous motors and asynchronous motors, depending on the engine concept permanent magnets are used in the rotor. So z. As EC motors, in which permanent magnets are located on the rotor surface known. These permanent magnets are realized in various embodiments. In arranging such perma- Magnetic magnets on the rotor surface, a return body is provided between the rotor shaft and the permanent magnets, which is fixedly connected to the rotor shaft. For example, annular realized permanent magnets are glued to this return body, so that a torque can be transmitted via the return body to the rotor shaft.

From DE 103 14 394 A1 a rotor for an EC motor and a method for mounting such a rotor are known. This known rotor has a shaft, a yoke body arranged on the shaft and a ring magnet surrounding the yoke body. Furthermore, a jacket is preferably provided which surrounds the ring magnet. The holding element and the jacket are integrally formed as a sleeve, wherein the ring magnet is also connected by pressing into the sleeve with this non-positively.

For EC motors, there are also efforts using plastic Umguss- the laminated core with the shaft to encase. As a result, however, typically only torque ranges for an EC motor with a realizable torque of less than 10 Nm can be realized. However, it is desirable to cover significantly higher torque ranges with the engines, which are in the range of 10Nm - 200 Nm. However, such aforementioned engines do not tolerate high process temperatures

Umgussverfahren after the permanent magnets are mounted, since it would lead to an undesirable demagnetization of the permanent magnets at high process temperatures, which limits the choice of material for the Umgussverfahren previously on non-metallic materials, such as plastics, as plastics typically a significantly low

Melting point of about 220 - 270 ° C compared to the process temperature of z. B. have aluminum die casting of about 700X.

In a known engine special type - called line-start engine - are in The rotor pockets provided to press permanent magnets in the pockets. A Line Start Permanent Magnet (LSPM) motor is a three-phase synchronous motor with asynchronous start-up, which additionally contains permanent magnets in the rotor with squirrel-cage rotor. Therefore, such motors also do not tolerate high process temperatures after the permanent magnets have been mounted since undesired demagnetization of the permanent magnets would also occur at the high process temperatures.

According to the current state of the art, therefore, permanent magnets in motor types in which the laminated core is exposed to high temperatures of the order of about 650 ° C. and higher can only be used in a subsequent production step. Another disadvantage of the line-start engines is the fact that the space available for the rings to be arranged on the front side and thus their effective cross-section is limited, which prevents minimizing the electrical resistance of the short-circuit cage and thus adversely affects the operating behavior of the engine.

The invention is therefore an object of the invention overcome above-mentioned disadvantages and on the one hand to provide a solution for manufacturing an EC motor and on the other hand a line-start motor, which is inexpensive to manufacture and in which the problem of demagnetization of permanent magnets is bypassed.

This object is achieved by the feature combination according to claim 1. A basic idea of the present invention is to provide a specific material combination in a defined mass ratio in the rotor. In fact, it has been found by research that at a certain weight ratio of the laminated core, the magnets and the Potting the problem of demagnetization of the magnets during encapsulation with a metallic potting compound, such. B. cast aluminum no longer or almost no longer occurs.

According to the invention, a rotor is provided with respect to an EC motor with internal rotor, which has a laminated core, which is formed from a stack of mutually insulated sheets and wherein in the laminated core several permanent magnets are radially introduced and wherein the laminated core surrounded with a metallic rotor casting and / / or partially and with the following mass ratios in mass% based on a total mass of 100% (formed from the laminated core, the permanent magnets and the rotor casting) are used:

- laminated core: 40 - 50 mass%,

- permanent magnets 40 - 50 mass%

- rotor casting 8 - 20 mass%. Thus, in a preferred embodiment of the invention, it has been shown that in an internal rotor rotor of a line-start engine, the following mass ratios have been shown as preferred embodiments:

- laminated core: 65 - 70 mass%,

- permanent magnets 10 - 20 mass% - rotor casting 10 - 30 mass%.

The sum of the components is to be taken into account with 100%, so that each selection of a value of weight% for one ingredient limits the choice for the other two ingredients and vice versa.

The permanent magnets are designed as magnetized ferrite elements. forms. In an EC motor, it is advantageous if the rotor casting is a casting of aluminum or an aluminum alloy and wherein the permanent magnets are held by the respective rotor casting directly in position. In a likewise advantageous embodiment of the invention in the EC motors is provided that in the rotor by means of the rotor casting a rotor shaft is cast.

In preferred embodiments of the invention it is further provided that the permanent magnets are introduced either in intermediate spaces between wedge-shaped radially outwardly extending teeth of the laminated core or in correspondingly shaped axially extending pockets.

It is also advantageous if the sheets and thus the laminated core are fixed by an inner bore filled with the rotor casting or is. A further aspect of the invention relates to a method for producing a rotor as above, in particular a rotor for an internal rotor of an electric motor, comprising the following steps: a. Providing mutually insulated sheets to form a lamination stack having spaces and / or pockets for receiving permanent magnets within the lamination stack; b. Introducing magnetized ferrite elements or permanent magnets into the spaces and / or pockets and c. Um- and or pouring the laminated core with a metallic casting material for producing a rotor casting, wherein the mass ratios are selected as follows: the laminated core is 40-50% by mass, the permanent magnets (3) are 40-50% by mass and the Rotor casting (4) is involved with 8-20 mass% of the total mass of 100%.

It is also advantageous if the rotor casting is cast between or around the laminated core such that both the laminated core and the permanent magnets are fixed by the rotor casting and the shaft and are preferably held in position.

In an advantageous embodiment of the invention in line-start motors is provided that the rotor is further penetrated by rods, which are predominantly or completely formed from the rotor casting. For electrical connection of the rods, these can be realized by means of end rings also made of the rotor casting material.

The permanent magnets are arranged in a preferred embodiment in each rotor pole of the laminated core in a substantially U-shaped arrangement to each other, wherein the laminated core is preferably formed as externally grout tes laminated core.

Other advantageous developments of the invention are characterized in the subclaims or are shown in more detail below together with the description of the preferred embodiment of the invention with reference to FIGS. Show it:

Fig. 1 is a sectional view through a first embodiment of a

EC-rotor;

Fig. 2 is a sectional view through a second embodiment of an EC rotor; 3 is a perspective view and a sectional view through a laminated core of a line-start rotor with inserted into pockets. added permanent magnets;

Fig. 4 is a die-cast over-molded rotor of a line-start engine.

The invention will be explained in more detail with reference to Figures 1 to 4, wherein like reference numerals refer to the same structural and / or functional features. FIGS. 1 and 2 respectively show sectional views of embodiments of a rotor 1 of an EC motor according to the present invention for internal rotor motors and in FIGS. 3 and 4 views of a line-start motor.

The rotor 1 in Figure 1 has a segmented laminated core 2 with radial segment arrangement, which is formed from a stack of mutually insulated sheets 20. The sheets 20 are formed as wedge-shaped sheets. In the laminated core 2 each permanent magnets 3 are introduced between the segments. The laminated core 2 is cast with a metallic rotor casting 4 as well as in the axially continuous openings 25 with the rotor casting material.

The rotor 1 is interspersed with rods 42 which are formed from the rotor casting 4, which extend through the openings 25 in the axial direction from one end of the laminated core 2 to the opposite end of the laminated core 2. The rods 42 connect the end flanges of the rotor 1 and ensure high rotor stability. The end flanges are additionally equipped with cooling vanes for improved engine cooling.

The laminated core 2 is internally fixed to the rotor casting 4, which has an inner bore 40 for a cast rotor shaft W, wherein the rotor casting 4 is formed with a groove 26 for the rotor shaft W. In detail 1 of Figure 1 this can be seen in an enlarged view. By this embodiment, in which the segments of the sheets 20, the permanent magnets 3 and the Rotorwel- are poured W, desired torques between about 10 Nm and 200 Nm can be realized, depending on the specific design.

The rotor casting 4 is formed in this embodiment of aluminum or alternatively of an aluminum alloy. FIG. 2 shows a similar embodiment as shown in FIG. 1, the teeth being fixed in a star shape and an annular section 2a of the laminated core 2 being formed between the rotor casting 4 designed as an inner ring. Between the inner end faces 3a of the permanent magnets 3 and the annular portion 2a of the laminated core 2, the rotor casting 4 is also cast, whereby the laminated core 2 is fixed. In detail 2.1 of Figure 2 this can be seen in an enlarged view. In the possible embodiment, the laminated core 2 is partially punched free to reduce stray flux, which is shown in detail 2.2 of Figure 2. 3 shows a perspective view of a line-start motor and including a sectional view through a laminated core 2 of a rotor 1, wherein the cuboid permanent magnets 3 in pockets 23 in an approximately U-shaped arrangement, each formed from three permanent magnets 3 for the two or four rotor poles are arranged. This embodiment also shows a rotor 1 for an internal rotor motor. Outside on the laminated core 2 additional grooves 21 are introduced in this embodiment, which are filled with the rotor casting 4.

4, the rotor 1, as shown in Figure 3, shown, wherein the grooves 21 are filled with rotor casting 4 and a die-casting with a rotor casting 4 is provided.

The rotor casting 4 fixes the permanent magnets 3 in the pockets 23 and closes them off from the front side. The end-side rings 27 are used for contacting tion of the rods 42 in the grooves 21 and can, as shown in the cross section in the circumferential direction are dimensioned correspondingly large.

As a practical embodiment, the rotor components for an EC motor consisting of laminated core, permanent magnets and cast aluminum for the internal rotor rotor were formed as follows:

Laminated cores of dynamo sheets: 46% by mass,

Permanent magnets: 42 mass%

Rotor casting: 12% by mass of the total mass of 100%. As a further practical embodiment, the rotor components of a line-start motor were formed consisting of laminated core, permanent magnets and cast aluminum as follows:

Laminated cores of dynamo sheets: 66 mass%,

Permanent magnets: 14 mass% rotor casting: 20 mass% of the total mass of 100%.

* * * * *

Claims

claims

1. rotor (1) for an internal rotor synchronous motor, wherein the rotor (1) has a laminated core (2) which is formed from a stack of mutually insulated sheets (20) and wherein in the laminated core (2) a plurality of permanent magnets (3) introduced are and where the laminated core

(2) with a metallic rotor casting (4) encapsulated and / or partially poured, characterized in that the laminated core with 40 - 70% by mass, the permanent magnets (3) with 10 - 50% by mass and the rotor casting (4) with 8 - 25 mass% of the total mass of 100% formed from the laminated core (2), the permanent magnet (3) and the rotor casting (4) are involved.

2. Rotor (1) according to claim 1, characterized in that the rotor is designed for a EC synchronous motor, wherein the laminated core with 40 - 50 mass%, the permanent magnets (3) with 40 - 50 mass% and the Rotor casting (4) with 8 - 25 mass% of the total mass of 100% formed from the laminated core (2), the permanent magnet

(3) and the rotor casting (4) are involved.

3. rotor (1) according to claim 1, characterized in that the rotor is designed for a line-start motor, wherein the laminated core with 60 - 70 mass%, the permanent magnets (3) with 10 - 20 mass% and the rotor casting (4) with 15-25 mass% of the total mass of 100% formed from the laminated core (2), the permanent magnet (3) and the rotor casting (4) are involved.

4. rotor (1) according to any one of the preceding claims, characterized in that the permanent magnets (3) are formed as magnetized ferrite elements.

5. rotor (1) according to any one of the preceding claims, characterized in that the rotor casting (4) is a casting of aluminum or an aluminum alloy.

6. rotor (1) according to claim 2, characterized in that in the rotor (1) by means of the rotor casting (4) a rotor shaft (W) is cast.

7. Rotor (1) according to any one of the preceding claims 1 to 6, characterized in that the permanent magnets (3) either in intermediate spaces (21) between wedge-shaped radially outwardly extending teeth (22) of the laminated core (2) or in accordance therewith formed axially extending pockets (23) are introduced.

8. rotor (1) according to any one of the preceding claims, characterized in that the laminated core (2) by a with the rotor casting (4) filled inner bore (40) are fixed.

9. rotor (1) according to one of the preceding claims, characterized in that the rotor (1) is further formed with rods (42) from the rotor casting (4) interspersed.

10. rotor (1) according to claim 3, characterized in that the permanent magnets (3) in each rotor pole of the laminated core (2) are arranged in a substantially U-shaped arrangement to each other, wherein the laminated core (2) preferably grooved as the outside Laminated core is formed.

11.Rotor (1) according to any one of the preceding claims, characterized in that the permanent magnets (3) of the rotor casting (4) are held in position.

12. A method for producing a rotor (1), in particular a rotor (1) for an internal rotor of a synchronous motor, comprising the following steps: a. Providing a laminated core (2) of mutually insulated sheets (20) with intermediate spaces (21) and / or pockets (23) for receiving permanent magnets (3); b. Introducing magnetized ferrite elements or permanent magnets (3) into the intermediate spaces (21) and / or pockets (23) and c. Umgießen and / or pouring the laminated core (2) with a metallic casting material for producing the rotor casting (4), wherein the mass ratios are selected as follows: the laminated core is with 40 - 70 mass%, the permanent magnets (3) are 10 - 50% by weight and the rotor casting (4) is involved with 8 - 25% by mass of the total mass of 100%.

13. The method according to claim 12, characterized in that the rotor casting (4) is poured between or around the laminated core (2) that both the laminated core (2) and the permanent magnets (3) of the rotor casting (4) are fixed ,