DE10349442A1 - Producing rotor for electrical machine with permanent magnetic stimulation involves heating baking lacquer coated magnets in plate packet openings until coating softened so magnets are baked together, to base body at coated contact surfaces - Google Patents

Abstract

The manufacturing method involves first coating the permanent magnets (17) with a baking lacquer coating (19), placing them in openings (16) in a plate packet (15) and finally heating the baking lacquer coating until it is sufficiently softened that the coated magnets are baked together and to the base body at their coated contact surfaces . An independent claim is also included for an electrical machine with a stator and a permanent magnetic rotor.

Description

State of technology

The The invention relates to an electric machine with permanent magnet rotor according to the preamble of claim 10 and a process for its preparation according to the preamble of claim 1.

A Subgroup of electrical machines are the brushless Machines whose rotors have a permanent magnetic excitation. In such machines are permanent magnets on the rotor circumference in the Usually with alternating polarity annular arranged and cooperate with a stator, in its winding In motor operation usually a rotating field is generated, which interacts with the magnetic fields of the permanent magnets and while taking the rotor with it. In addition to those for the engine function in the electromagnetic sense important requirements such as magnetic flux and demagnetization resistance There are other requirements for the permanent magnets. In here addressed machines consist of the permanent magnets of NdFeB and need a corrosion protection, for example made of aluminum, nickel or Epoxy resin. On the other hand, eddy currents occur at high speeds. which reduces by an electrical insulation of the magnets to each other can be. In a known manner, the permanent magnets are special for this purpose coated or coated with an insulating material, which at the same time as Corrosion protection is used. Furthermore, must the permanent magnets in the rotor are firmly inserted in order to operate occurring mechanical and thermal stress their reliability to ensure. For this purpose, the permanent magnets in a known manner by gluing, plastic molding or by mechanical means on their preferably as a laminated core trained body fixed.

The The above requirements are in the known solutions several separate measures ensured. This is how the already coated permanent magnets become by gluing, plastic molding or by positive joining or in their main body attached. Gluing and plastic molding are manufacturing processes, which require high investment and because of their time and temperature critical Process parameters are difficult to control. The procedures require Furthermore tight manufacturing tolerances of the individual parts, resulting in increased manufacturing costs caused. For positive locking Add the permanent magnets is an increased handling effort in production necessary, especially since this often additional inserts, for example Springs, needed become. In electrical machines with small dimensions is also a machine joining the permanent magnets hardly feasible.

With the present solution is sought, the above requirements when using the To realize permanent magnets with simplified measures.

Advantages of invention

The inventive manufacturing method of Rotor with the identification features of claim 1 has the advantage that corrosion protection, electrical insulation and tight fit of the Permanent magnets in the main body or laminated core of the electric machine with only one Coating of the permanent magnets can be realized, making special activities for magnetic attachment such as gluing, plastic molding or positive joining accounts. By using a baked enamel coating, similar to of copper wires known as anti-corrosive, electrically insulating sheath Finally, the permanent magnets also become the permanent magnets of the individual permanent magnets still glued together with each other and with the laminated core or baked.

By in the subclaims listed activities arise advantageous embodiments and further developments of specified in the main claim features.

A particularly simple and reliable attachment of the permanent magnets can be achieved in that the coated permanent magnets are inserted and baked in recesses of the laminated core, which are punched out of the sheets of the laminated core as axial, segmental openings. To achieve wide pole faces on the circumference of the rotor while minimizing the eddy current losses and taking into account optimal magnet geometries you can arrange several coated permanent magnets on the circumference side by side, which then form a magnetic pole. Furthermore, depending on the length of the rotor of the electric machine, two or more coated permanent magnets per pole are expediently inserted axially one behind the other into the apertures of the laminated core, which in turn minimizes the eddy current losses and optimizes the magnet geometry. A particularly intimate baking of the axially consecutive permanent magnets with each other can be achieved that the permanent magnets are pressed axially against each other by magnetically ineffective end plates of the two end faces of the laminated core ago. For this purpose, it is ensured in a particularly simple manner by appropriate coordination of the lengths of the laminated core and the permanent magnets that the coated permanent magnets project somewhat after insertion into the openings of the laminated core at the two end faces, so that when heating a particularly intimate, surface caking the end discs is realized with the adjoining, under compression permanent magnets. In the simplest way, the end plates are pressed onto a rotor shaft carrying the laminated core. Since the baked enamel layer can be applied to the permanent magnets with different thicknesses, the baked enamel layer is advantageously dimensioned so thickly, for example by repeated immersion in liquid baked enamel, that it compensates for manufacturing tolerances of the permanent magnets and the punching and length tolerances of punching the laminated core.

For a sufficient reliable connection of the permanent magnets with the laminated core is to strive the Backlackverklebung as possible form a large area. For this purpose, in a further development of the invention, the permanent magnets before insertion into the recesses of the laminated core, at least but before heating the baked enamel layer, pre-magnetized. By the then effective magnetic forces pressed the permanent magnets against the laminated core, so that when heated, the baked enamel layers the permanent magnets flat be baked with the laminated core.

drawing

The The invention is explained in more detail below by way of example with reference to FIGS. It demonstrate:

1 an electrical machine with a rotor equipped with permanent magnets in longitudinal section,

2 the electric machine off 1 in cross section,

3 a coated permanent magnet in cross-section and

4 the same permanent magnet in front view.

description of the embodiment

In 1 is as an inventive electric machine, an EC motor shown in longitudinal section and with 10 designated. 2 shows a cross section through this machine 10 after the line II-II 1 , It has a stationary stator 11 with a polyphase winding 12 and it has a rotor designed as a permanent magnet rotor 13 acting as a main body on a rotor shaft 14 Pressed laminated core 15 having. In recesses 16 the laminated core 15 are per pole several permanent magnets 17 for permanent magnetic excitation of the rotor 13 or the electric machine 10 arranged axially one behind the other and in the circumferential direction next to one another. The permanent magnets 17 are magnetized such that they form a north pole on the circumference of the upper rotor half and a south pole on the circumference of the lower rotor half. The poles of the rotor 13 act over a working air gap 18 with the stator 11 together, in which in a known manner by an electrical commutation through the coils of the stator winding 12 a magnetic rotating field is generated, which is the rotor 13 with synchronous speed entrains.

3 shows one of the permanent magnets 17 in cross section according to the line III-III 4 and 4 shows the same permanent magnet 17 in the plan view before insertion into the recesses 16 the laminated core 15 , which by segmental punching the sheets of the laminated core 15 were formed.

To the permanent magnets 17 to protect against corrosion, to electrically isolate them from each other to reduce eddy current losses and around them in the recesses 16 To fix, the permanent magnets are first individually with a baked enamel layer 19 coated, which is dimensioned in its thickness so that it tolerance variations between the permanent magnets 17 and the recesses 16 the laminated core 15 compensate so far that they without effort in the recesses 16 the laminated core 15 according to several 1 axially behind one another and according to 2 in pairs in the circumferential direction next to each other in the openings or recesses 16 the laminated core 15 be used. Subsequently, the rotor with the inserted, coated permanent magnets 17 so far heated that the baked enamel layer 19 is softened and that then the coated permanent magnets 17 at their lateral contact surfaces 19a respectively 19b together and at their outer and / or inner contact surfaces 19c . 19d with the laminated core 15 be baked flat. The axially consecutive, coated permanent magnets 17 are in their axial length so on the axial length of the laminated core 15 matched that after inserting into the recesses 16 the laminated core 15 initially protrude slightly at both ends. After that are from the two end faces of the laminated core 15 each a magnetically ineffective end plate 20 on the rotor shaft 14 pressed and when heating the rotor 13 become these endplates 20 from both sides against the protruding faces 19e and 19f the coated permanent magnets under compressive stress 17 pressed. When softening the baked enamel layer 19 then become the front side pressed against each other permanent magnets 17 through the baked enamel layer 19 baked together flat.

For the preparation of the baked enamel layer 19 who the plastics such as polyester imide, polyamide imide and aromatic polyamide used, as is already known in the baking of enameled copper wire. The Verbacktemperatur of about 200 ° Celsius is well below the temperatures critical for the unmagnetized magnet, so that damage to the magnets is ruled out. The typical values for the heating of the rotors during operation, especially in motor vehicles, at around 160 ° Celsius, are well below the temperatures for a re-softening of the baked enamel layers 19 from about 220 ° Celsius. Thus, a replacement of the permanent magnets 17 from the laminated core 15 not given during operation. After baking the coated permanent magnets 17 with each other and with the laminated core 15 Finally, the permanent magnets in a known manner by applying strong magnetic fields from the outer peripheral surface of the laminated core 15 forth in the according 2 magnetized shown polarity.

To the baking of the baked enamel coating 19 with the laminated core 15 form as large as possible, it is still possible, the permanent magnets 17 before insertion into the recesses 16 the laminated core 15 or after insertion and before heating the baked enamel layer 19 magnetize, giving it by the magnetic force of the permanent magnets 17 to the laminated core 15 pressed and when softening the baked enamel layer 19 by heating with the laminated core 15 be baked flat.

Because the laminated core 15 with the recesses 16 through the two end discs 20 closed on both sides, the baked enamel layer 19 when heating not from the recesses 16 escape. This is an intimate caking of the permanent magnets 17 with each other and with the laminated core 15 guaranteed. Optionally, it can for better distribution of the baked enamel layer 19 the rotor 13 even during the baking of the baked enamel coating 19 be quickly turned and / or swiveled.

Claims (10)

Method for producing a rotor ( 13 ) with a permanent magnetic excitation by a plurality of permanent magnets ( 17 ) coated with an electrically insulating and anti-corrosive layer in recesses ( 16 ) one preferably as part of the rotor ( 13 ) formed body, in particular a laminated core ( 15 ) are inserted and fastened, characterized in that the permanent magnets ( 17 ) individually with a baked enamel coating ( 19 ) that they then in the recesses ( 16 ) of the laminated core ( 15 ) and finally that by heating the baked enamel coating ( 19 ) is softened to the extent that the coated permanent magnets ( 17 ) on their baked enamel-coated contact surfaces ( 19a . 19b . 19c . 19e . 19f ) with each other and with the basic body ( 15 ) are baked. A method according to claim 1, characterized in that in each case a plurality of the coated with baked enamel permanent magnets ( 17 ) in segment-shaped, designed as axial openings recesses ( 16 ) of the basic body ( 15 ) are used and baked in it. A method according to claim 2, characterized in that the coated permanent magnets ( 17 ) per pole in the circumferential direction in pairs next to each other in the recesses ( 16 ) of the basic body ( 15 ) are used. A method according to claim 2 or 3, characterized in that several coated permanent magnets ( 17 ) per pole axially one behind the other into the recesses ( 16 ) of the basic body ( 15 ) are used. A method according to claim 4, characterized in that the coated permanent magnets ( 17 ) by magnetically inactive end discs ( 20 ) from the two end faces of the main body ( 15 ) ago axially pressed against each other. A method according to claim 5, characterized in that the coated permanent magnets ( 17 ) after insertion into the recesses ( 16 ) of the basic body ( 15 ) protrude slightly at the two end faces and that when heating the end plates ( 20 ) against the protruding faces ( 19a ) of the coated permanent magnets ( 17 ). Method according to one of claims 5 or 6, characterized in that the end discs ( 20 ) on a body ( 15 ) supporting rotor shaft ( 14 ) are pressed. Method according to one of the preceding claims, characterized in that the baked enamel layer ( 19 ) is dimensioned so thick that it produces manufacturing tolerances of the permanent magnets ( 17 ) and the recesses ( 16 ) of the basic body ( 15 ) compensates. Method according to one of the preceding claims, characterized in that the permanent magnets ( 17 ) before heating the baked enamel layer ( 19 ), in particular before insertion into the recesses ( 16 ) of the basic body ( 15 ), be magnetized so that they by magnetic force to the body ( 15 ) are pressed and baked flat with this when heating. Electric machine ( 10 ) with a stator ( 11 ) and one over a working air gap ( 18 ) co-operating rotor ( 13 ) with a permanent magnetic excitation by a plurality of permanent magnets ( 17 ) coated with an electrically insulating and anti-corrosive layer in recesses ( 16 ) of a preferably formed as part of the rotor body, in particular a laminated core ( 15 ) are inserted and fastened, characterized in that the permanent magnets ( 17 ) according to the characterizing features of claim 1 in the recesses ( 16 ) of the basic body ( 15 ) through a baked enamel layer ( 19 ) with each other and with basic body ( 15 ) are baked.