Assembly for an electric machine, method for manufacturing an assembly and electric machine with an assembly

Abstract

Assembly (10; 10a; 10b) for an electric machine (1), comprising a rotor (12; 12a; 12b) rotatable in a rotational axis (11) and magnetic elements (15; 15a) arranged on the circumference of the rotor (12; 12a; 12b) and connected to the rotor (12; 12a; 12b), wherein the connection between the rotor (12; 12a; 12b) and the magnetic elements (15; 15a) is formed as a soldered connection (25), characterized in that the rotor (12b) has at least one slot-shaped recess (35) in the area of ​​overlap with the respective magnetic element (15), which extends from the circumferential surface (13) of the rotor (12b), such that at least one connecting web (36) is formed on which the soldered connection (25) is formed.

Description

State of the art

[0001] The invention relates to an assembly for an electric machine according to the preamble of claim 1. Furthermore, the invention relates to a method for manufacturing an assembly according to the invention, as well as an electric machine and the use of an assembly according to the invention.

[0002] An assembly for an electric machine according to the preamble of claim 1 is already known from practice. This assembly is a component, for example, of an electric motor, in which permanent magnet elements are arranged on the circumference of a rotatably mounted rotor. The permanent magnet elements, hereinafter referred to simply as magnet elements, interact with stationary and energizable wire coils arranged, in particular, in the area of ​​a pole housing. In practice, such magnet elements are attached to the circumference of the rotor by gluing, taping, or by means of a positive-locking connection between the magnet elements and the rotor. Furthermore, it is known to integrate the magnet elements into the rotor structure.In any case, a mechanically secure connection between the magnetic elements and the rotor is desirable to prevent the magnetic elements from detaching from the rotor's circumference due to centrifugal forces during rotation, which would inevitably lead to malfunction or destruction of the electric motor. Furthermore, relatively simple assembly that is particularly easy to monitor during process control, as well as high efficiency for an electric machine equipped with this assembly, are desirable. A disadvantage of magnetic elements connected to the rotor either by positive locking or by integration into the rotor structure is that the electric machine exhibits relatively poor efficiency due to magnetic interactions with the magnetically conductive rotor material.Bonding the magnetic elements to the rotor is considered disadvantageous because the adhesive tends to outgas and requires a specific curing time to securely fix the magnetic elements to the rotor. During this curing time, further processing or assembly of the rotor to the electric machine is at least temporarily impossible. Furthermore, depending on the specific circumstances, the assembly accuracy of a bonded connection may not be optimal. When the magnetic elements are wrapped around the rotor structure, the wrapping material increases the air gap between the wire windings and the magnetic elements, thus also reducing the achievable efficiency.

[0003] The printed document FR 807 676 A shows a rotor with soldered-on magnets. Disclosure of the invention

[0004] Based on the prior art described above, the invention aims to further develop an assembly for an electric machine according to the preamble of claim 1 in such a way as to avoid the aforementioned disadvantages. This objective is achieved according to the invention in an assembly for an electric machine with the features of claim 1 by forming the connection between the rotor and the magnetic elements as a soldered joint. A soldered joint, as a material-bonded connection, has the particular advantage over an adhesive joint that the magnetic elements are particularly firmly connected to the rotor, so that particularly high radial forces can be transmitted. This has the advantage that an electric machine equipped with an assembly according to the invention enables particularly high rotational speeds.Furthermore, the connection is load-bearing up to the melting temperature of the solder, and depending on the solder chosen, a relatively high operating temperature is possible compared to an adhesive bond. Such a high operating temperature is only achievable with an adhesive bond using special adhesives, which may be relatively expensive and / or complex to process. It is also considered advantageous that outgassing, as occurs with adhesives, is avoided and that a particularly good thermal bond between the magnetic elements and the rotor is achieved. The manufacturing and assembly time of an assembly according to the invention is also reduced compared to the prior art, as no curing time is required, as is the case when using an adhesive.

[0005] Advantageous further developments of the assembly according to the invention are listed in the dependent claims.

[0006] In a first further development of the assembly, it is proposed that the magnetic elements be provided with a coating to improve solderability. Such a coating can be applied, for example, to NdFeB magnetic elements with Ni when using Sn-based solder.

[0007] To achieve the highest possible efficiency, it is further proposed that the shape of the magnetic elements be adapted, at least substantially, to the shape of the rotor's cross-section at the connection point with the magnetic elements. This means that the magnetic elements are designed, in particular, as segments of circular arcs, with only the relatively thin solder layer needing to be taken into account between the rotor's outer circumference and the magnetic elements.

[0008] To prevent mechanical stresses in the magnetic material of the magnetic elements, which arise, for example, due to the different coefficients of thermal expansion of the materials of the magnetic elements and the rotor, a further advantageous embodiment of the invention provides that the rotor, in the area of ​​contact with the respective magnetic element, has at least one, preferably several, slot-shaped recesses extending from the circumferential surface of the rotor. In the conventional design of such motors or magnetic elements, these recesses also run parallel to the axis of rotation of the rotor.

[0009] A particularly good connection of the magnetic elements to the rotor is achieved if the connection between the rotor and the magnetic elements has a positive locking connection in addition to the soldered connection.

[0010] In a specific embodiment, such a positive-locking connection comprises at least one, preferably two, projections arranged on opposite sides of the rotor or the magnetic elements, which interact with a corresponding recess on the magnetic element or the rotor. Using only one positive-locking connection offers the advantage that only a soldered joint is required on one side between the rotor and the magnetic element, while, in particular, the positive-locking connection is formed on the side opposite the soldered joint, preferably with some play. Such a design allows the corresponding element to expand in the area of ​​the positive-locking connection when the magnetic element or the rotor heats up, thus avoiding or at least reducing mechanical stresses.

[0011] In a method for manufacturing an assembly according to the invention, in which the magnetic elements are connected to the rotor by means of a material-bonded connection, it is provided according to the invention that the magnetic elements are soldered to the rotor.

[0012] Possible suitable soldering methods include both application soldering and friction or joining soldering.

[0013] Furthermore, a first possible method involves using magnetic elements that are unmagnetized before being connected to the rotor. This method has the advantage that, particularly at relatively high temperatures, such as those typically encountered during soldering depending on the solder used, demagnetization losses in magnetized magnetic elements can be avoided. This allows the use of a solder with a relatively high melting point (which thus permits particularly high thermal stresses on the rotor) without additional measures, and without having to accept a reduced efficiency of the electric machine due to weakly magnetized magnetic elements.

[0014] Alternatively, it is also possible to use magnetic elements that are already magnetized before being connected to the rotor. From a manufacturing perspective, this method may be easier to integrate into the assembly process, as it eliminates the need for subsequent magnetization of the magnetic elements.

[0015] In order to avoid or reduce demagnetization of the magnets in the latter variant of the method, where magnetized elements are used prior to connection with the rotor, the demagnetization temperature of the magnets can be increased during soldering to the rotor. Such an increase in the demagnetization temperature can be achieved by using a suitable device known in the prior art.

[0016] Furthermore, it may be provided that the soldered connection between the magnetic elements and the rotor is only formed over a portion of the overlap area in the circumferential direction, in order to simplify the manufacturing process and, if necessary, to better compensate for mechanical stresses resulting from uneven stresses due to uneven heating of the magnetic elements.

[0017] Finally, the invention also includes an electric machine, in particular as a component of a comfort drive in a motor vehicle, comprising an assembly according to the invention or an assembly manufactured according to a described method. Such a comfort drive in a motor vehicle is understood to include, in particular but not limited to, a window regulator drive, seat adjustment drive, sunroof drive, or similar device.

[0018] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing.

[0019] This shows in: Fig. 1 a simplified cross-section through an assembly according to the invention, in which a magnetic element is connected to a rotor by means of a soldered connection, Fig. 2 one opposite Fig. 1 modified assembly in which a magnetic element is additionally connected to the rotor by a positive locking connection and Fig. 3 one opposite Fig. 1 modified assembly using longitudinally extending slots on the rotor.

[0020] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0021] In the Fig. Figure 1 is a simplified representation of a first assembly 10 according to the invention for an electric machine 1. The machine 1 is, in particular, an electric motor as part of a comfort drive in a motor vehicle, such as a seat adjustment drive, a window regulator drive, a sunroof drive, or the like. However, the invention is not intended to be limited to such uses of an assembly 10.

[0022] The assembly 10 comprises a rotor 12 rotatably mounted in a rotary axis 11, which in practice usually consists of a multitude of components in the plane of the drawing. Fig. The assembly consists of 1 vertically stacked sheet metal elements, rotatably mounted on an axis (not shown) that simultaneously forms the axis of rotation 11. Ideally, the rotor 12 has a circular cylindrical circumferential surface 13 to which several, at least two, but in practice, for example, four, magnetic elements 15 are attached. For the sake of simplicity, only a single magnetic element 15 is shown in the figures. The magnetic element 15 has a circular arc segment shape such that the inner circumferential surface 16 of the magnetic element 15 is substantially adapted to the circumferential surface 13 of the rotor 12. The magnetic elements 15 of the assembly 10 interact with alternately currentable wire windings 18, the wires of which run substantially perpendicular to the plane of the drawing and which radially surround the magnetic elements 15 with a small gap.For this purpose, the wire windings 18 are arranged, for example, on the inner circumference of a stator 20 of the machine 1 and additionally potted with it.

[0023] According to the invention, the connection between the magnetic element 15 and the rotor 12 is made by a soldered connection 25. In the case of the Fig. In the embodiment shown in Figure 1, the solder 26 of the soldered joint 25, with a relatively small layer thickness, is arranged between the circumferential surface 13 and the magnetic element 15 such that it extends over the entire arc segment of the magnetic element 15. For example, several of these elements can be arranged perpendicular to the plane of the drawing. Fig. 1. Arranged, each circular arc-shaped section with the plumb line 26 is provided, such that the plumb line 26 is not arranged in the entire overlap area between the rotor 12 and the corresponding magnetic element 15. In modification of the one described in the Fig. In the embodiment shown in 1, it can also be provided that the plumb line 26 runs, for example, only over a partial area of ​​the circular arc segment between the magnetic element 15 and the rotor 12 and, for example, perpendicular to the plane of the drawing. Fig. 1 over the entire length of the magnetic element 15.

[0024] During the Fig. In the assembly 10a shown in Figure 2, a positive-locking connection 30 is provided between the rotor 12a and the magnetic elements 15a, in addition to the soldered connection 25. For this purpose, the magnetic element 15a has a longitudinal orientation, i.e., perpendicular to the plane of the drawing. Fig. 2 On the opposing end faces, each rotor 12a has an approximately semicircular recess 31, 32, which interacts with a corresponding protrusion 33, 34. The solder 26 of the soldered joint 25 is located in the area of ​​the positive-locking connection 30, i.e., in particular in the area of ​​the recesses 31, 32 and the protrusions 33, 34. Because the solder 26 is located in this area, a certain mounting gap is also allowed between the magnetic element 15a and the rotor 12a, which facilitates the mounting of the magnetic elements 15a to the rotor 12a.

[0025] The one in Fig. The assembly 10b shown in Figure 3 differs from the assembly 10a according to the Fig. 1 by the fact that in the overlap area between the rotor 12b and the magnetic element 15 in the circumferential surface 13 of the rotor 12b in the longitudinal direction, that is, perpendicular to the plane of the drawing Fig. 3 at least one, in the illustrated embodiment two longitudinal slots 35 are formed. Connecting webs 36 are formed on the rotor 12b through the longitudinal slots 35, on which the soldered joint 25 is formed or the solder 26 is arranged. Between the in the Fig. In addition to the two connecting bridges 36 shown in Figure 3, the rotor 12b has a central area 37 between which and the facing surface of the magnetic element 15 no soldered connection 25 is formed.

[0026] It is further mentioned that for all assemblies 10, 10a and 10b, it is possible to use both magnetic elements 15, 15a that were magnetized before soldering to the rotor 12, 12a, 12b, and those that are magnetized only after the connection. Furthermore, it may be possible to provide the magnetic elements 15, 15a with a coating, particularly to improve solderability. The invention is also, in principle, transferable to other types of machines, for example, linear motors.

Claims

[1] Assembly (10; 10a; 10b) for an electrical machine (1), comprising a rotor (12; 12a; 12b) rotatable in a rotational axis (11) and magnetic elements (15; 15a) arranged on the circumference of the rotor (12; 12a; 12b) and connected to the rotor (12; 12a; 12b), wherein the connection between the rotor (12; 12a; 12b) and the magnetic elements (15; 15a) is designed as a soldered connection (25), characterized by that the rotor (12b) has at least one slot-shaped recess (35) in the overlap area with the respective magnetic element (15), which extends from the circumferential surface (13) of the rotor (12b), so that at least one connecting web (36) is formed on which the soldered connection (25) is formed. [2] Assembly according to claim 1, characterized by that the magnetic elements (15; 15a) are provided with a coating to improve solderability. [3] Assembly according to claim 1 or 2, characterized bythat the shape of the magnetic elements (15; 15a) corresponds at least substantially to the shape of the cross section of the rotor (12; 12a; 12b) at the connection region with the magnetic elements (15; 15a) and is in particular designed in the shape of a circular arc section. [4] Assembly according to one of claims 1 to 3, characterized by that the rotor (12b) has a plurality of slot-shaped recesses (35) in the overlap area. [5] Assembly according to one of claims 1 to 4, characterized by that the connection between the rotor (12a) and the magnetic elements (15a) additionally has a positive connection (30). [6] Assembly according to claim 5, characterized by that the positive connection (30) comprises at least one, preferably two, projections (33, 34) arranged on opposite sides of the rotor (12a) or the magnetic element (15a), which projections cooperate with an oppositely identical recess (31, 32) in the magnetic element (15a) or in the rotor (12a). [7] Method for producing an assembly (10; 10a; 10b) according to one of claims 1 to 6, in which magnetic elements (15; 15a) are connected to a rotor (12; 12a; 12b) by means of a material connection, characterized by that the magnetic elements (15; 15a) are soldered to the rotor (12; 12a; 12b). [8] Method according to claim 7, characterized by that the soldering process used is a deposition, friction or joint soldering process. [9] Method according to claim 7 or 8, characterized by that magnetic elements (15; 15a) are used which are unmagnetized magnetic elements (15; 15a) which are only magnetized after connection to the rotor (12; 12a; 12b). [10] Method according to claim 7 or 8, characterized by that magnetic elements (15; 15a) are used which are magnetized before being connected to the rotor (12; 12a; 12b). [11] Method according to claim 10, characterized bythat the demagnetization temperature of the magnetic elements (15; 15a) is increased during soldering to the rotor (12; 12a; 12b). [12] Method according to one of claims 7 to 11, characterized by that the soldered connection (25) between the magnetic elements (15; 15a) and the rotor (12a; 12b) is formed only over a partial area of ​​the overlap area in the circumferential direction. [13] Electric machine (1), in particular as a component of a comfort drive in a motor vehicle, comprising an assembly (10; 10a; 10b) according to one of claims 1 to 6 or an assembly (10; 10a; 10b) produced by a method according to one of claims 7 to 11.

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