DE102016211600A1 - Electric machine comprising a rotor and a stator - Google Patents

Abstract

The invention relates to an electric machine comprising a rotor (20) and a stator (30), wherein the rotor (20) or the stator (30) has a plurality of rows (40, 41), each juxtaposed in the axial direction, on its circumference Circumferentially arranged magnet (50, 51, 52), wherein the magnets (50, 51, 52) of each individual row (40, 41) are circumferentially spaced from each other and the magnets (50, 51, 52) of adjacent rows (40 , 41) are each arranged with offset in the circumferential direction to each other, wherein the offset of the magnets (50, 51, 52) relative to a reference line (60) in the axial direction through the center of one of the magnets (50) one of the outermost rows ( 40), is irregular over all rows (40, 41) seen.

Description

Field of the invention

The invention relates to an electrical machine comprising a rotor and a stator.

State of the art

In order to minimize the so-called cogging torque (cogging torque) and especially of airborne and structure-borne noise, among other things a skewing of the arrangement of the magnets in the rotor or in the stator is provided in electrical machines. Especially in permanent magnet synchronous machines with single tooth winding, the skewing in the rotor is realized by an angular offset of the individual rotor segments or magnets due to structural conditions. Usually, this is done either by a so-called linear skew, as in 4 is shown, or a V-skew, as in 6 is shown. In the case of the linear bevel, the magnets which are adjacent in the axial direction have 50 ' 51 ' of the rotor 20 ' standing in a stator 30 ' is arranged, from top to bottom, a gradually increasing displacement to a reference line 60 ' on. The offset in the axial direction of adjacent rows 40 ' . 41 ' rises gradually in linear slanting. The offset in the axial direction of adjacent rows 44 ' . 45 ' rises gradually at V-slope and then gradually decreases again.

In 5a) -F) is a section along this reference line 60 ' shown. The 5a) -F) show the time course of the occurring forces 70 ' in the respective magnets 50 ' . 51 ' , With V-skewing, the offset of the magnets increases 52 ' From the top to the bottom first gradually and then gradually decreases (symmetrically) again. The reference line 61 ' runs in 6 in the axial direction of the rotor 21 ' on the peripheral surface of the rotor 21 ' through the middle of the top magnet 52 ' , The rotor 21 ' is in a stator 31 ' arranged. 7a) -F) each show a section along this reference line 61 ' , The 7a) -F) show the time course of the occurring forces 71 '' on the surface of the rotor.

Due to the oblique arrangement or skewing or grading of the magnets, the effective reluctance torque is distributed over a wider angular range (in the circumferential direction of the rotor). In the case without a skew, this would be concentrated on the area of each magnetic pole or magnet. In addition to the reluctance torque, which is caused by a tangential force component with respect to the rotor surface, usually also radial forces act in the machine. These are usually the main cause of noise emissions, as the radial forces are introduced through the teeth in the housing and this vibrates excited (it is said that the housing "breathes").

In 5 and 7 in the subfigures a) -f) the spatial and temporal course of the force excitation of a tooth in the axial direction of the electric machine for a linear and a V-skew during the passage of a pole or magnets are shown. The influence of the following pole or magnet is deliberately omitted. The length of the arrows indicates the amount of forces. Striking here is the high symmetry of the force excitation in linear skew as well as V-taper.

In the case of linear skew ( 5 ), the tooth is usually excited from left to right in a quasi-continuous wave. In the case of the V-skew, there are two waves, which usually move from the left and from the right towards the middle and meet there ( 7 ). This form of excitation generally favors oscillations of the housing and, consequently, sound radiation, in particular if the excitation frequency corresponds to one or the natural frequency of the electrical machine.

Disclosure of the invention

Advantages of the invention

Embodiments of the present invention may advantageously allow to minimize the vibration and sound radiation of the electric machine.

According to a first aspect of the invention, an electric machine comprising a rotor and a stator is proposed, wherein the rotor or the stator has on its periphery a plurality of axially juxtaposed rows of circumferentially successively arranged magnets, the magnets of each individual row are circumferentially spaced from each other and the magnets of adjacent rows are each arranged with offset in the circumferential direction to each other, characterized in that the offset of the magnets with respect to a reference line extending in the axial direction through the center of one of the magnets of the outermost rows, over all Rows seen are irregular.

An advantage of this is that the forces occurring are usually distributed over the magnets irregularly over time. Thus, as a rule, no large local forces occur in (in the axial direction) directly adjacent magnets. There are typically the force excitations at different points of the magnets juxtaposed in the axial direction, ie magnets not immediately adjacent rows, introduced and there is usually no "spatially and temporally wavy" excitation, but only a temporally harmonious excitation of the adjacent magnets in the axial direction instead. This usually reduces the vibrations occurring and thus the sound radiation, since no natural frequency of the electric machine is excited. Also, usually no frequency near the natural frequency of the electric machine is excited or the spatial force application points in combination with the temporal occurrence of the excitation do not match the associated eigenmodes of the oscillation. Thus, in the electrical machine usually little effort for damping measures must be taken. This usually saves time and reduces costs. In addition, as a rule, the electric machine can be produced cost-neutral on production facilities for electrical machines according to the prior art without significant changes.

The electric machine can be used or arranged in a vehicle or motor vehicle.

The respective optimal displacements of the magnets to the reference line can be determined by means of a computer. In the calculation, the suspension or mounting of the electric machine, the size of the rotor and the stator and many other variables that co-determine the natural frequency of the electric machine, are taken into account. For the exact same machine, the arrangement of the magnets can usually remain the same, i. The rotor with the arrangement of the magnets can also be identical.

The value of the respective offset of the magnets relative to the reference line may correspond to a random function. An advantage of this is that typically the occurrence of uniform vibrations and thus the sound radiation is further reduced.

The offset of the magnets may be formed differently sized from row to row with respect to the reference line. The advantage of this is that as a rule the sound radiation is reduced even further.

The magnets of each individual row can be arranged regularly or irregularly along the circumferential direction. An advantage of an irregular arrangement is that usually the forces occurring are even better distributed. This usually reduces the sound radiation even further.

The magnets of each individual row can have the same spacing in the circumferential direction. As a result, usually the individual rows or the magnets arranged side by side in the axial direction can be produced one after the other by the same tool (for example punching tool). This typically reduces manufacturing costs.

The magnets can each have the same length when viewed in the circumferential direction. As a result, the production of the electric machine is usually further simplified. This usually reduces manufacturing costs.

The magnets of each row can have the same width when viewed in the axial direction. An advantage of this is that the production of the electric machine is usually further simplified. This typically reduces manufacturing costs.

The magnets may comprise permanent magnets, in particular the magnets may be permanent magnets. An advantage of this is that the electrical machine is usually inexpensive to produce. In addition, the electric machine can usually be operated technically simple.

The electric machine may be a reluctance machine and the magnets may be the poles of the rotor made of a high permeability, soft magnetic material. Thus, usually in a reluctance machine, the forces occurring over time can be distributed over magnets or magnetic poles or poles which are far apart from each other or are not immediately adjacent. As a result, the vibrations occurring and the sound radiation typically fall.

Ideas for embodiments of the present invention may be considered, inter alia, as being based on the thoughts and findings described below.

Brief description of the drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which neither the drawings nor the description are to be construed as limiting the invention.

1 shows a perspective view of an embodiment of a rotor of the electric machine according to the invention;

2 shows an axial section through in the axial direction of adjacent magnets 1 , along the line 60 ;

3 shows an axial section through in the axial direction of adjacent magnets 1 along the line 62 ;

4 shows a perspective view of a rotor of a linear oblique electric machine according to the prior art;

5 shows an axial section through in the axial direction of adjacent magnets 4 along the line 60 ';

6 shows a perspective view of a rotor of a V-shaped electric machine according to the prior art; and

7 shows an axial section through in the axial direction of adjacent magnets 6 along the line 61 ' ,

The figures are only schematic and not to scale. Like reference numerals designate the same or equivalent features in the figures.

Embodiments of the invention

1 shows a perspective view of an embodiment of a rotor 20 the electric machine according to the invention. 2 shows an axial section through axially adjacent magnets 50 . 51 . 52 out 1 , along the line 60 , 3 shows an axial section through axially adjacent magnets 50 . 51 52 out 1 along the line 62 , Not all magnets adjacent in the axial direction become this 50 . 51 . 52 cut from the reference line 60 get cut.

The rotor 20 is from a stator 30 surrounded by the electric machine. The rotor 20 has an axis of rotation 80 on that in 1 runs from top to bottom. On the peripheral surface of the rotor 20 are rows 40 . 41 of magnets 50 . 51 . 52 arranged. The rows 40 . 41 are in the axial direction (in 1 running from top to bottom) arranged side by side. The rows 40 . 41 each comprise several magnets 50 . 51 . 52 in the circumferential direction. The magnets 50 . 51 . 52 a row 40 . 41 are to the next magnet 50 . 51 . 52 the respective row 40 . 41 spaced in the circumferential direction. In the in 1 shown embodiment are eleven rows 40 . 41 of magnets 50 . 51 . 52 available. Another number of rows 40 . 41 is conceivable. Every row 40 . 41 includes in the 1 shown embodiment, the same number of magnets 50 . 51 . 52 , namely 14 Magnets. However, it is also conceivable that the number of magnets 50 . 51 . 52 in the rows 40 . 41 is different in size.

The magnets 50 . 51 . 52 each have the same size in the axial direction. In the circumferential direction, the magnets 50 . 51 . 52 each the same length or size. However, it is also conceivable that the size in the axial direction and / or the length in the circumferential direction of the magnets 50 . 51 . 52 is different.

The distance of a magnet 50 . 51 . 52 a row 40 . 41 to the two immediately adjacent magnets of the same row 40 . 41 in the circumferential direction is in 1 each same size. It is also conceivable that the distances of a magnet 50 . 51 . 52 to which each immediately adjacent is different. This means that the distances of the magnets to each other within a row 40 . 41 in different rows 40 . 41 can be different in size. It is also conceivable that the distance between the magnets in the circumferential direction within a row 40 . 41 is different in size.

Through the middle of the magnet 50 the outermost row 40 (in 1 the top magnet 50 in the middle of the picture) is a reference line 60 , The reference line 60 runs in the axial direction (ie parallel to the axis of rotation 80 of the rotor 20 ). However, it is also conceivable that the middle of another magnet of the top row 40 in 1 or the middle of a magnet of the bottom row in 1 as a reference line 60 is selected. It is essential that the once selected reference line 60 is maintained.

The magnets 50 . 51 . 52 of the ranks 40 . 41 have irregular offsets in the circumferential direction with respect to the reference line 60 on. This means that the magnets 50 . 51 . 52 , unlike in the prior art, in which they in linear skew from top to bottom in 4 have a gradually increasing offset or distance in the circumferential direction and in which they at V-taper from top to bottom in 6 have an initially gradually increasing offset and then again have a decreasing offset, no particular or mathematical rule following offsets or distances to the reference line 60 exhibit.

Irregular means that the offsets of the magnets 50 . 51 . 52 which are adjacent in the axial direction, to the reference line 60 follow no (simple mathematical) rule and / or scheme. In the axial direction adjacent are in 1 the magnets 50 . 51 . 52 through which the reference line 60 runs.

The offset of a magnet 50 . 51 . 52 can be determined by the distance of a point (eg the center or the center or a fixed edge or end of the magnet 50 . 51 . 52 ) to the reference line 60 determined along the circumferential direction become. Accordingly, the second-highest magnet 51 in 1 another offset to the reference line 60 on as the third magnet 52 from the top in 1 as the third highest magnet 52 is offset to the left in the circumferential direction and thus another offset to the reference line 60 has as the second highest magnet 51 , The second highest magnet 51 is right in 1 in relation to the reference line 60 added. The offset of the third highest magnet 53 is thus negative, while the offset of the second-highest magnet 52 is positive. Negative is the offset then when the center of each magnet 51 . 52 to the left of the reference line 60 in 1 located. The choice of the sign of the offset is arbitrary, but must - once selected - maintained.

Of course, another line parallel to the in 1 shown reference line 60 runs, be defined as a reference line. The decisive factor is that the reference line is the same line for all magnets adjacent in the axial direction 50 . 51 . 52 , The line 62 runs parallel to the reference line 60 ,

Also, instead of the middle of the top magnet 50 in 1 the middle of the bottom magnet in 1 be used as a position for determining the offset. It is crucial that for the adjacent magnets in the axial direction 50 . 51 . 52 in each case the same reference line is used to determine the offset.

Before the magnets 50 . 51 . 52 on the rotor 20 will be arranged, the optimal arrangement of the magnets 50 . 51 . 52 or the optimal offset of the magnets 50 . 51 . 52 or the rows 40 . 41 calculated. For this purpose, by means of a computer, the forces occurring 70 for different arrangements and different offsets or distances of the magnets 50 . 51 . 52 in the circumferential direction to the reference line 60 calculated. It is taking into account the suspension or attachment of the electric machine, the size of the rotor 20 and the stator 30 and many other variables that co-determine the natural frequency of the electric machine, an arrangement determines the lowest possible vibrations of the electric machine or the rotor 20 arise during operation. Consequently, an arrangement of the magnets 50 . 51 . 52 or offsets of the magnets 50 . 51 . 52 determined, in which the least possible sound (audible sound or structure-borne noise) is generated. The magnets 50 . 51 . 52 are then in this arrangement on the rotor 20 arranged or attached thereto.

In the intermediate areas or recesses 58 in the circumferential direction between the magnets (one row 40 . 41 ) sheets may be arranged such that a flush surface of the rotor 20 arises. The magnets 50 . 51 . 52 are thus in pockets or recesses of a sheet or sheets. The thickness of the magnets 50 . 51 . 52 in the radial direction of the rotor 20 is then substantially the thickness of the (non-magnetic) sheets in the radial direction of the rotor 20 ,

The stator (not shown in FIG 1 ) has a plurality of electromagnets, so that the electric machine by rotation of the rotor 20 Can generate electricity or due to an electric current in the stator of the rotor 20 rotates. It is also conceivable that the stator has the described magnets and the rotor 20 several electromagnets.

The magnets 50 . 51 . 52 can be permanent magnets. It is also conceivable that the magnets 50 . 51 . 52 Partial permanent magnets and partially electromagnets are. It is also conceivable that the magnets 50 . 51 . 52 Electromagnets are.

In the context of the present application, a magnet is also understood to mean a magnetizable material which only temporarily has a magnetic pole or magnetic poles. In particular, the magnet may be a high-permeability, soft-magnetic material, which is the pole of a rotor 20 used in a reluctance machine. In the axial direction of the rotor 20 Thus, the highly permeable, soft-magnetic material is present in different angular positions or extends over respectively different angular ranges. The respective width of said material in the circumferential direction of the rotor 20 can each be the same size. Thus, even with such a rotor 20 the forces occurring 70 on areas of the rotor 20 distributed in time, which are not immediately adjacent or close together, but on areas that are far away from each other. As a result, the excitation of the natural frequency or natural frequencies of the electric machine or of frequencies close to these frequencies is prevented even in a reluctance machine. This lowers the sound radiation.

The magnets of each row 40 . 41 each have the same distance to the immediately adjacent circumferentially magnet 50 . 51 . 52 on. However, it is also conceivable that the distances in the circumferential direction are each different.

The pockets or recesses in which the magnets 50 . 51 . 52 be included or in which the magnets 50 . 51 . 52 are arranged are punched out of a sheet.

The rows 40 . 41 of magnets 50 . 51 . 52 can be arranged such that a small distance between the magnets 50 . 51 . 52 exists in the axial direction. However, it is also conceivable that no distance in the axial direction between the magnets 50 . 51 . 52 is available.

The offsets of the magnets 50 . 51 . 52 from the magnets 50 . 51 . 52 which are adjacent in the axial direction (ie the magnets 50 . 51 . 52 through which in 1 the reference line 60 runs), each can be different from each other. This means that no magnet 50 . 51 . 52 the magnets adjacent in the axial direction 50 . 51 . 52 the same offset to the reference line 60 having. As a result, the temporal and spatial distribution of the forces occurring 70 especially well distributed.

The distance of a magnet 50 . 51 . 52 to the circumferentially immediately adjacent magnet is in each case by the size of the recess 58 certainly.

In the circumferential direction of the rotor 20 repeats itself in 1 at fixed angular intervals, the arrangement of the magnets.

The magnets 50 . 51 . 52 may be covered by another layer, the surface of the further layer being the surface of the rotor 20 forms. This layer is in 2 and in 3 shown (as well as in 5 and in 7 ), but not in 1 ,

Finally, it should be noted that terms such as "comprising," "comprising," etc., do not exclude other elements or steps, and terms such as "a" or "an" do not exclude a multitude. Reference signs in the claims are not to be considered as limiting.

Claims (9)

Electric machine comprising a rotor ( 20 ) and a stator ( 30 ), wherein the rotor ( 20 ) or the stator ( 30 ) on its circumference a plurality of rows arranged side by side in the axial direction ( 40 . 41 ) of each circumferentially arranged magnet ( 50 . 51 . 52 ), wherein the magnets ( 50 . 51 . 52 ) of each single row ( 40 . 41 ) are circumferentially spaced from each other and the magnets ( 50 . 51 . 52 ) of adjacent rows ( 40 . 41 ) are each arranged with offset in the circumferential direction to each other, characterized in that the offset of the magnets ( 50 . 51 . 52 ) relative to a reference line ( 60 ) in the axial direction through the middle of one of the magnets ( 50 ) one of the outermost rows ( 40 ), across all rows ( 40 . 41 ) is irregular. Electric machine according to claim 1, wherein the value of the respective offset of the magnets ( 50 . 51 . 52 ) relative to the reference line ( 60 ) corresponds to a random function. Electric machine according to claim 1 or 2, wherein the offset of the magnets ( 50 . 51 . 52 ) relative to the reference line ( 60 ) of series ( 40 . 41 ) to row ( 40 . 41 ) is formed differently large. Electric machine according to one of the preceding claims, wherein the magnets ( 50 . 51 . 52 ) of each single row ( 40 . 41 ) are arranged regularly or irregularly along the circumferential direction. Electric machine according to one of the preceding claims, wherein the magnets ( 50 . 51 . 52 ) of each single row ( 40 . 41 ) in the circumferential direction have the same distance. Electric machine according to one of the preceding claims, wherein the magnets ( 50 . 51 . 52 ) seen in the circumferential direction each have the same length. Electric machine according to one of the preceding claims, wherein the magnets ( 50 . 51 . 52 ) each row ( 40 . 41 ) in the axial direction, each having the same width. Electric machine according to one of the preceding claims, wherein the magnets ( 50 . 51 . 52 ) Comprise permanent magnets, in particular permanent magnets are. Electric machine according to one of the preceding claims, wherein the electric machine is a reluctance machine and the magnets ( 50 . 51 . 52 ) which are made of a highly permeable, soft magnetic material poles of the rotor.

Images