EP1792380A1

EP1792380A1 - Secondary part of an electric machine

Info

Publication number: EP1792380A1
Application number: EP05794454A
Authority: EP
Inventors: Thomas Hoppe; Zeljko Jajtic; Gerhard Matscheko; Christian Volmert
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2004-09-22
Filing date: 2005-09-21
Publication date: 2007-06-06
Also published as: JP2008514175A; US20070236090A1; WO2006032255A1; JP2008514168A; US20070222304A1; DE102004045992A1; EP1792385A1; WO2006032638A1; US7800256B2; EP1792385B1; CN101023570A; CN101027827A; CN101023570B; US7638916B2

Abstract

The invention relates to a secondary part (5,7) of an electric machine (1,3) and/or the electric machine itself (1,3). Said electric machine (1,3) comprises a primary part (9,11) and a secondary part (5,7). The primary part (9,11) comprises a winding (21) and permanent magnets (17). According to the invention, the secondary part (5,7) comprises non-laminated teeth (13).

Description

description

Secondary part of an electrical machine

The invention relates to a secondary part of an electric machine or an electrical machine itself. The electric machine has a primary part and a secondary part. The primary part has electrical windings. The electric machine is, for example, a synchronous machine, an asynchronous machine, a stepping motor or the like. The electric machine may be e.g. Both a line armotor or act to a motor, or generator, by which a rotational movement is executable.

From the German application with the official file reference 10 2004 045 992.4, for example, an electrical machine is known whose secondary part has no active means for generating a magnetic field. Such active means are, for example, permanent magnets or also windings which can be energetically energized. In a permanent magnet excited synchronous linear motor with permanent magnet-free secondary part, for example, the primary part has energizable windings and permanent magnets, wherein the secondary part has a tooth structure made of a ferrous material, the teeth of the secondary part facing the primary part. From this application, a passive secondary part is known, this laminated is executed. The use of a secondary därteils, which has a sheet metal, is complicated and time-consuming in the production.

Object of the present invention is to provide a simplified secondary part of an electrical machine.

Such a simplified structure is particularly desirable in a linear motor, since linear motors can have, for example, secondary parts whose size in a direction of movement can exceed the size of the primary part in the direction of movement by a multiple. The object can be achieved, for example, by means of a secondary part of an electric machine having the features according to claim 1, or else by means of an electric machine according to claim 8. The subclaims 1 to 7 and 9 are inventive embodiments or developments of the respective device according to FIG of claims 1 and 8.

An inventive secondary part of an electrical machine has a tooth profile. The tooth profile results from a cross section of the secondary part, wherein the tooth profile is formed by teeth. In the case of a ready-to-operate electric machine, which has a primary part in addition to the secondary part, the teeth are turned toward the primary part. Through the teeth, it follows that the primary part to the secondary part has at least two different distances. The secondary part is designed in such a way that it is made non-wicked. Thus, the secondary part does not have any plates arranged next to one another, in particular in the sense of a laminated core, wherein such a plate, by which a laminated core is formed, serves in particular for the reduction of eddy currents. Laminated packages are used in particular for primary parts. With regard to the tooth profile, it should be noted that it is formed by teeth which have a longitudinal extent which is approximately perpendicular to a direction of movement of the electrical machine. The direction of movement can be linear or rotatory nature. A tooth is thus a kind of Rie¬ gel, wherein a cross-section, which cuts a plurality of bars approximately perpendicular to their longitudinal extent discloses the tooth profile.

The tooth profile can be formed in such a way that this different profile shapes, i. Has geometries. Examples of geometries are a rectangular shape, a triangular shape, a sine shape, etc.

The production of a laminated secondary part is aufwen¬ dig. The lamination relates in particular to a layering of metal sheets whose abutting boundary surfaces are perpendicular to a plane which can be formed by an air gap of the electric machine, this being a characteristic of a known laminated core. By using a structure of the secondary part, which is free of such Schicht¬ structure, as this arises in a laminated core, the production or the construction of the secondary part is considerably simplified as a packaging omitted. This also simplifies the possibilities for means for fastening the secondary part, for example on a machine bed.

Secondary parts in a laminated design have low eddy current losses. The eddy current losses occur in particular at high frequencies. The frequencies refer to a fundamental frequency of an alternating current, with which the primary part of the electric machine is fed or is fed.

An electric machine is constructed, for example, such that it has a primary part and a secondary part, wherein the primary part is designed in such a way that it has two means for generating a magnetic field. The secondary part is executable free of means for generating a magnetic field. The primary part therefore has a first means for generating a magnetic field and a further means for generating a magnetic field, wherein the first means for generating a magnetic field can be acted upon by an alternating voltage or an alternating current. The first means for generating a magnetic field which is a first magnetic

Field is, for example, is a winding. The additional means for generating a magnetic field, which is an excitation field, is a means with which a further, ie at least a second, magnetic field can be generated. The field excitation which generates the additional magnetic field is advantageously unchanged during operation, ie, constant. Such a further means for generating the further magnetic field is, for example, a permanent magnet or a winding, which is acted upon or acted upon by a particular constant current. The further means for generating a further magnetic field advantageously has a multiplicity of further means for generating a magnetic alternating pole field excitation. The first means for generating a first magnetic field is, for example, a coil winding, wherein the first magnetic field exiting or entering the coil in such a way to further means (ie second, third, etc.) for generating further magnetic field is directed that at least two further means for generating weite¬ rer magnetic fields in the field region of the first Magneti¬'s field are, so that an interaction of the two magnetic fields comes about. The further means for generating further magnetic fields advantageously have a multiplicity of mutually opposite directions of magnetization, with which an arrangement with an alternating pole magnetization is established.

The electric machine, which has a primary part and a secondary part, wherein the primary part has a first means for generating a first magnetic field and the secondary part has a means for guiding the magnetic field is thus designed such that the primary part has at least two further means for generating at least two further magnetic fields, wherein the first means for generating the first magnetic field is arranged to the further means for generating the further magnetic Fel¬ that a superposition of the first magnetic field with the other magnetic Fields is made possible light.

Such a construction of the electric machine has the advantage that the secondary part of the electric machine can be built up in such a way that it has no active means for generating a magnetic field. However, at least the secondary part can be built up in such a way that it can be used in partial areas which lead to the formation of an electromagnetic force are provided, has no magnetically active means. The secondary part of such an electric machine advantageously has only one means for guiding magnetic fields and is therefore simple and inexpensive to manufacture. The secondary part is designed, for example, to be laminated, in order to avoid eddy currents, such an embodiment being expensive and expensive. For the structural design of the primary part and secondary part advantageously soft iron parts are used. The sheet metal of these parts reduces eddy currents.

In an advantageous embodiment, the soft iron parts of the secondary part are solid and / or designed as so-called iron powder pressed parts.

In an advantageous embodiment of the secondary part according to the invention, this has a tooth carrier, wherein the teeth are made in one piece with the tooth carrier. Due to the one-piece design of the toothed secondary part is dispensed with a sheet metal. A sheet is especially at

Basic frequencies of the alternating electrical current in the primary part of greater than 25 Hz necessary because the eddy current losses increase with increasing frequency and the resulting motor force decreases. The non-wicked secondary part is therefore used advantageously in electrical machines, which are operated predominantly with an AC frequency of less than 25 Hz. A further field of application of the non-perforated secondary part results in electrical machines in which the decrease of the engine power with increasing frequencies or with increasing motor speed on the part of the drive request specification is permissible.

Secondary parts for electrical machines for operating states with a predominant fundamental frequency of the electrical Wech¬ selstromes of more than 25 Hz are advantageously designed ge bleed or have measures for the suppression of eddy currents. In a further embodiment of the secondary part, this has a tooth carrier, wherein at least one tooth is connected to the tooth carrier by means of a connection means. The tooth carrier is, for example, a carrier plate on which teeth are mounted. Since the teeth have a longitudinal direction transversely to the direction of movement of the electric machine, they can also be characterized as a kind of bar. The carrier plate itself serves, for example, for attaching the secondary part in or on a machine. Examples of such machines are machine tools,

Production machines or automatic handling machines. The carrier plate is then mounted on a machine bed, in particular. Pre-assembly of the teeth on a separate carrier plate simplifies installation in the machine. In a further embodiment of the tooth carrier, this is a part of the machine, in which, in particular, the electrical machine is installed in the design of a linear motor. It is also possible, for example, to use the machine bed of a machine as a tooth carrier. As connection means for the attachment of the teeth on the tooth carrier, a multiplicity of connection types can be used, for example: a screw connection, a riveted connection, a welded connection, a press connection, a positive connection, etc.

The teeth of a secondary part can be produced, for example, from a single material, wherein the single material can also be an alloy or another material mixture. Depending on the method of manufacture and the construction of the secondary part, the material of the teeth may differ from the tooth carrier material or be identical to it. Various features of types of production of the secondary part are listed below:

• the secondary part is milled from a metal plate; • the secondary part is manufactured by means of a gray cast iron process; the side of the gray cast is post-processing (eg milling, grinding, etc.). subjected, which faces the primary part in the electric machine and contributes to the formation of the Luft¬ gap;

The secondary part has metal rods which are welded and / or riveted, and / or screwed onto a metal plate acting as a tooth carrier;

The secondary part has a metal sheet which has a tooth profile; For example, the tooth profile can be impressed into a metal sheet by means of an embossing process, the sheet metal having a planar shape in particular before embossing.

If, in the case of a secondary part, the teeth are formed in a direction transverse to the direction of movement of the electric machine by means of a metal sheet, the metal sheet having a tooth profile, the secondary part can be formed both from a material and from a combination of materials , The embossing of a tooth profile in a metal sheet (sheet metal) is an example of a particularly simple and rapid way of producing such a secondary part. The embossing results in grooves, which can be filled, for example, with a soft magnetic material or an iron-plastic mixture. Such a mixture is also usable as a filling material of pipes. A pipe used as a tooth has in particular a rectangular cross-section. A filling of the groove or the pipe er¬ increases, for example, in a groove not only the stability, but also leads in particular to a reduction of mag¬ genetic losses. In the case of a mixture of a plastic and a metal, the magnetically conductive metal particles are separated by the plastic, so that with good magnetic conductivity, eddy currents can also be avoided or at least reduced. In a filled groove, as well as in a filled tube, teeth of the secondary part have at least two materials. The filling of the teeth has iron for guiding the magnetic flux, whereby a cavity is at least reduced or even completely filled by the filling. If the stamped sheet or tube is made of iron, they themselves carry some of the magnetic flux. If it is a thin-walled sheet metal, its wall thickness may not be sufficient for the guidance of the entire magnetic flow, as the thin sheet magnetically saturates, which can have a negative effect on the engine power. In such a case, it is also advantageous to use a soft-magnetic, ie, "ferrous," filling in such a case, In a further embodiment, the magnetic function of the embossed sheet can be dispensed with altogether Pipe, then serve only as a dimensionally stable packaging material and / or as a mounting or fastening aid for the magnetically relevant filling material for magnetic flux guidance Plastic is then used, for example, as a means for receiving därteils acting on the tooth structure of Sekun¬ acting magnetic feed and attraction forces of the linear motor.

In a further embodiment, the filling itself is mechanically strong and stable after the production process of the secondary part, so that the dimensionally stable packaging material serves only as a "shaping template" for the filling during the production of the secondary part This has the advantage that the air gap of the electric machine can be kept small, for example, the filling is made of a ferrite material which hardens after a sintering process.

In an advantageous embodiment, the metal sheet is not only embossed but also stamped. By means of the punching, for example, holes for fastening the secondary part can be produced by means of screws or rivets.

If a sheet metal is used for the formation of the secondary part, then for this purpose either several sheets can be stacked on top of each other. or only one sheet is used. In the case of a plurality of metal sheets, the boundary surfaces between the metal sheets in the area of the air gap of the electric machine are parallel to the plane formed by the air gap.

In order to reduce the eddy current losses in a secondary part, this can also be formed as follows. On the one hand, it is advantageous to use at least sintered teeth. In addition, the tooth carrier can also be sintered, in which case teeth and tooth carriers can also be made in one piece. Sintered teeth or the sintered tooth carrier can be produced, for example, by means of a powder pressing method. By using the sintering technique, eddy current losses can be reduced.

On the other hand, such a reduction of eddy current losses can also be achieved by means of an injection molding process. The teeth, the tooth carrier, or the secondary part can be produced in an injection molding machine as injection molded parts. The material used for the injection-molded part is a metal-enriched plastic. Injection molded parts are simple and inexpensive to produce. Even a one-piece construction of teeth and tooth carrier is easy to implement. With the aid of the injection molding process, it is also possible to inject an injection-molded part which can be used as an insert for fastening the secondary part to the machine bed.

A secondary part according to the invention, as already described above, can also be embodied in a further embodiment in such a way that the tooth has at least two materials. Die¬ this structure is eg realizable such that a tooth has a pipe. This tube has, for example, a rectangular cross section, so that it can easily be mounted on a flat surface which is formed by a tooth carrier. The tube may be made of stainless steel or aluminum, wherein the wall thickness of the tube is preferably thin. To limit the magnetic losses, the tube may be filled with a material which has a magnetic flux passes. For example, an iron-plastic mixture can be used for the filling material. This has the advantage that eddy current losses are reduced despite the omission of a laminated core. The tube is connected, for example by means of a welded connection with the tooth carrier.

In a further embodiment of the secondary part, these teeth have teeth which form a kind of groove. An example of a gutter is a tube with a rectangular cross-section in which one side is missing so that the tube becomes a gutter. The gutter is usable as a tooth, the gutter, like the tube, being filled with a filling material and the open side of the gutter e.g. adjacent to the tooth carrier. The open side may also be directed towards the primary part, in which case the open side faces away from the tooth carrier.

Both the tube and the channel are examples of a secondary part, in which a cavity is formed by means of a tooth, the cavity being filled with a material which comprises a metal, in particular iron.

In addition to the secondary part of an electrical machine, the invention also relates to the electrical machine itself. According to the invention, an electric machine which has a primary part and a secondary part, wherein the secondary part has a tooth profile, can be formed in such a way that one or more teeth of the secondary part are executed non-wicking. The lamination relates in particular to a lamination in which the sheets are lined up in such a way that this ranking is at least approximately perpendicular to an air gap of the electric machine. In such an electrical machine, a secondary part is advantageously used, as described in the preceding description, or is shown by way of example below in the figures.

The following figures show examples of erfindungsge¬ Permitted embodiments of secondary parts of electrical Maschi¬ NEN. Showing: 1 shows a schematic representation of a linear motor with permanent magnets on a primary part,

2 shows a cross-sectional view of a linear motor

3 shows a first cross section of a secondary part of a linear motor

4 shows a further cross section of a secondary part ei¬ nes linear motor

5 a rectangular shaped tooth profile of a secondary part FIG. 6 a wave-shaped tooth profile of a secondary part

7 shows a wavy embossed tooth profile of a secondary därteils

8 shows a toothed profile screwed onto a tooth carrier FIG. 9 shows a tooth profile in a rotary electric machine

1 shows an electrical machine 1 in the form of a linear motor. The electrical machine 1 has a primary part 9 and a secondary part 5. The primary part 9 has a winding 21, permanent magnets 17 and a laminated core 23. The possible direction of movement of the primary part 3 is marked by means of a double arrow 37 which extends in a longitudinal direction of the electric machine. The perspective of a side view is indicated by an arrow 41, wherein FIGS. 2 to 8 use this side view to illustrate a cross section of the secondary part. The laminated primary part 9 has permanent magnets 17 on the side which faces the secondary part 5. The permanent magnets 17 are mounted on the primary part 9 in such a way that their magnetization alternates. The permanent magnets thus generate a magnetic flux which alternates always in its orientation transversely to an air gap 43. The air gap between the primary part 9 and the secondary part 5 forms an air gap plane, wherein the secondary part 5 has teeth 13, wherein the teeth 13 of the secondary part adjoin this air gap 43. The movement of the electric machine 1, which in the present In this case, it is possible that either the primary part 9 is stationary and the secondary part 5 moves or that the secondary part 5 is stationary and the primary part 9 extends beyond the secondary part 5 emotional. The winding 21 is a first means for generating a first magnetic field and the permanent magnets 17 are further means for generating further magnetic fields.

The secondary part 5 has a tooth carrier 19. On this tooth carrier 19 teeth 13 are arranged. The tooth-like structure becomes clear in the side view 41. The side view 41 takes place transversely to a possible direction of movement 37 of the electric machine 1, this representing a longitudinal direction of the electric machine. The teeth 13 also have a longitudinal direction, but this longitudinal direction of the teeth corresponds to the transverse direction 39 of the electric machine 1. The teeth 13 of the secondary part 5 are fi xed on a tooth carrier 19. The teeth 13, which may also be referred to as bars, are glued or soldered or welded onto the carrier 19, for example, or joined together in a combination of fastening possibilities. Since in particular at low base frequencies of the alternating current, with which the windings of the primary part are energized, the negative eddy current effects are not pronounced, can be dispensed with a sheet and, for example. a kosten¬ favorable solid part can be used as a tooth. Low fundamental frequencies are in a range of less than 25 Hz.

The illustration according to FIG. 2 schematically shows the cross section of a linear motor, wherein the cross-sectional plane runs parallel or along a direction of movement 37 of the linear motor. The secondary part 5 is made in one piece and has teeth 13. The primary part 9 has not only permanent magnets 17 but also windings 21. The windings encompass winding teeth 15 of the primary part 9. Winding heads 22 of the windings are represented symbolically by arcs. The illustration according to FIG. 3 shows a further example of the possible construction of a secondary part 5. The secondary part according to FIG. 3 shows a tooth carrier 19 on which teeth 13 are welded. The teeth 13 have a 4-edge tube 25. This tube 25 is filled with a filling material 27. The filling material 27 is, for example, an iron-plastic mixture. The tube 25, which consists for example of iron or aluminum is connected by welds 29 fixed to the tooth carrier 19.

The representation according to FIG. 4 shows teeth 13, which are designed as grooves 31, wherein the grooves 31 are filled with a filling material 27. The filling material 27 advantageously has a soft magnetic material.

The illustration according to FIG. 5 shows a secondary part 5, which shows a metal sheet 33 fitting on the tooth carrier 19. The sheet 33 is shown in FIG 5 in a cross-sectional profile. The cross-section is designed such that it has rectangular-shaped teeth 13 in cross-section.

The illustration according to FIG. 6 shows a secondary part 5, which shows a metal sheet 33 fitting on the tooth carrier 19. The sheet 33 is shown in FIG 6 in a cross-sectional profile. The cross section is designed such that this has cross-sectionally wave-shaped teeth 13.

The illustration according to FIG. 7 shows a secondary part 5, which shows a metal sheet 33 abutting on the tooth carrier 19. The sheet 33 is shown in FIG 7 in a cross-sectional profile.

The cross section is formed such that it has triangular teeth 13 in cross section.

By means of different tooth geometries, which are shown for example in FIGS. 5 to 7, engine properties can be specifically influenced and / or optimized. The aim of optimizing or influencing, for example, is: a reduction of disturbing cogging forces, A reduction of harmonics in the induced voltage,

An improved "sinusoidality" of the induced voltage, etc.

As shown, the different cross-sections can be realized particularly simply by means of a different wave form of an embossed sheet.

The teeth according to the illustrations according to FIGS. 4 to 7 have a longitudinal extent transverse to the direction of movement of the electrical machine, which has such a secondary part with the corresponding tooth profile. This longitudinal expansion of the teeth is not illustrated in FIGS. 4 to 7, but this becomes apparent from FIG.

The illustration according to FIG. 8 shows a perspective view of a secondary part 5, which has a sheet 33 of rectangular cross section, the sheet being fastened to the tooth carrier 19 by means of screws 45. This illustration according to FIG. 8 also shows the longitudinal extent 47 of the teeth 13, the longitudinal extent of the teeth 13 being aligned transversely to a longitudinal direction 37 of the secondary part 5.

The teeth 13 may be provided with a side termination. This side termination is used, for example, to form a cavity in which the filling material 27 can be filled without this running out again. Thus, a mold is formed for filling the filling material. The Seitenab¬ conclusion, which is located on the longitudinal end faces of the secondary part 5, is not shown in FIG 8 for reasons of clarity.

The direction of movement supported by the electric machine can be linear or rotational. The illustrations according to FIGS. 1 to 8 relate to linear directions of movement in the longitudinal direction 37. The illustration 9 shows a detail of a cross section of a rotary electric machine 3. This electric machine 3 has a primary part 11 and a secondary part 7. Both parts have a circular cross-section. The primary part 11, like the primary part of a linear motor, has windings 21, winding teeth 15 and permanent magnets 17. The secondary part 7 has teeth 13, wherein the teeth 13 are spaced from the primary part 11 through the air gap 43. In FIG. 9, by way of example, the secondary part 7 is made in one piece. The teeth 13 have an unillustrated longitudinal orientation along a rotation axis 47, so that teeth form a kind of bolt, wherein a cross-section, which cuts a plurality of bars approximately perpendicular to their longitudinal extent, the tooth profile disclosed.

Claims

claims

1. Secondary part (5, 7) of an electric machine (1, 3), which has a tooth profile, but one or more teeth (13) of the secondary part (5, 7) are made unborn.

Second abutment (5,7) according to claim 1, characterized in that the secondary part (5,7) comprises a tooth carrier (19), wherein teeth (13) with the tooth carrier (19) is made in one piece.

3. secondary part (5,7) according to claim 1, dadurchge¬ indicates that the secondary part (5,7) comprises a tooth carrier (19), wherein at least one tooth (13) mit¬ means of a connecting means (29) with the tooth carrier ( 19) is connected.

4. Abutment (5, 7) according to one of claims 1 to 3, characterized in that the tooth

(13):

• has at least two materials and / or

• manufactured by means of an injection molding process or a powder pressing process.

5. Secondary part (5,7) according to claim 4, characterized in that a cavity can be formed by means of a tooth (13), wherein the cavity is filled with a material having iron.

6. Secondary part (5,7) according to any one of claims 1 to 5, d a d u c h e c e n e c i n e in that teeth (13) are formed by means of a sheet (33), wherein the sheet metal

(33) has a tooth profile.

7. secondary part (5,7) according to one of claims 1 to 5, da¬ characterized in that the tooth (13) has a tube (25).

8. Electrical machine (1,3), which is in particular a Line¬ armotor (1), which has a primary part (9,11) and a Sekun¬ därteil (5,7), wherein the secondary part (5,7) a Having tooth profile, dadurchgekennzeic net that one or more teeth (13) of the secondary part (5,7) are made unbeaten.

9. Electric machine (1, 3) according to claim 8, characterized in that it has a secondary part (5, 7) according to one of claims 1 to 7.