DE8138692U1 - COLLECTORLESS DC MOTOR - Google Patents

Description

PATENTANV / ALT RAJBLE TELEFON (Ο7 \\) 'β% ψ, ⁴ Ρ , J {. *

7OÖO STLITTGART1 TELEGRAMS »ABCLRAT'STUTTGARIJ

5f

7OÖO STLITTGART1 TELEGRAMS »ABCLRATSTUTTGARIJ \

LENBAO-1STRASSE 32 POSTSCHECK 53, TLfTTOART 74400-708 "rMfal Ifvl / ^ LJAMO CDAIQI t =

(AM K1LUSSBERG) LANDESGiROKASSE STUTTGART 2 916 076 LJIr "^ L. ~ IIN» d. MMlNO l ~ </ AIDl_tZ.

APPROVED VIb AT THE EUROR PATENT OFFICE EUROPEAN PATENT ATTORNEY

ι. jj "" .. - "~, - STUTTGART.DEN 06/30/1984

Removal from G 81 19 065.4 attorney's file = P61.22D138 / m

PAPST-MOTOREN GMBH & CO KG

Brushless DC motor

The invention relates to a brushless direct current motor (internal rotor motor, external rotor motor, motor with a flat air gap, etc.), with a stator and a permanent magnetic rotor. The invention is particularly suitable for two-pulse people Motors with reluctance auxiliary torque. - Such motors are known from DE-OS 25 14 067.

Unusual magnetizations for the rotors of electrical machines are known from the prior art. So shows E.g. US Pat. No. 3,969,644 a tachometer generator, namely a device which, when rotated, generates pulses in a Hall IC, which is located between two magnetic disks of a rotor. This Hall IC requires a to operate asymmetrical alternating magnetic field. That's why they are

Rotor disks magnetized in such a way that the north poles have a width of 24 °, while the south poles only have a width of 12 °, i.e. the north poles are twice as wide as the south poles. This results in a flow course as it is for such asymmetrical ones Hall IC's is cheap. Such a magnetization would, however, be unsuitable for a motor, for example, and would cause the torque to develop unevenly.

-ET-

·) ·. · At ■■

From US - PS 4 143 288 it is also known to use an annular Permanent magnets of a small motor to provide recesses on the edge, in which balancing weights of the rotor protrude. These counterweights can be in the usual catfish Ü be partially milled off in order to dynamically balance the rotor. These cutouts in the permanent magnet result in a continuous area in the area of the cutouts reduced induction, which increases the power of the motor accordingly

decreased.

From US Pat. No. 4,086,519 it is known to use special magnets for generating the Hall signals, which are attached to the rotor at a different location than the actual rotor magnet and therefore - with a clever arrangement - are less influenced by stray fields, so that results in a more precise Hall signal. Such an arrangement is, however, much iu expensive for many small motors, ie the galvanomagnetic Γ) sensor has to be controlled directly by the rotor magnet there and special control magnets cannot be used.

It is therefore an object of the invention to improve motors of the type mentioned at the beginning.

This object is achieved according to the invention in a brushless DC motor mentioned at the outset in that Poles of the rotor magnet in their middle angle of rotation range each have at least one zone relative to the induction curve in the remaining part of these poles of reduced induction

t ff ft I ti I

point. This gives a very favorable shape for the rotor magnet in the stator winding induced voltage, the so-called back EMF, and thus a more favorable form of the ■ <j stator current as a function of the angle of rotation of the rotor. Through this you can reduce the torque fluctuations of such a motor and, if necessary, improve its performance.

A particularly advantageous embodiment of such a motor f J is characterized in that it has an at least almost cylindrical air gap, that the poles of the rotor each have an axial protrusion area with a magnetization for controlling at least one galvanomagnetic sensor arranged outside the air gap, in particular a Hall IC , and that the zones with reduced induction each lie in these overhang areas. An external rotor motor with a cylindrical air gap is known from US Pat. No. 4,286. In this known motor, the poles of the rotor,

(Λ are what separated by slanted pole gaps (which ■ also in the present invention is readily possible is) each achieve a smooth running an axial supernatant region having a magnetization for controlling two outside of the air gap disposed HaIlgeneratoren. If it is desired in such a motor A corresponding protrusion area must also be provided at the opposite end of the rotor, ie "the rotor - and thus the motor - becomes unnecessarily long. The subject matter of the claim makes it possible to make this protrusion area at the opposite end of the rotor significantly smaller, i.e. a shorter overall length

· ■ Il I · * ·

of the engine, as the subject of claim 5 is. Thus, by using the subject matter of claim 2, the overhang areas of the rotor magnet can be made unequal in size without creating an undesirably large pulsating force acting on the rotor in the axial direction. In spite of this, you get a precise commutation of the stator currents at the desired points and a clear control of these currents depending on the rotor position. Such a motor also operates then very satisfactory when applied to its rotor from outside an axial force f as the example at an axial fan of the case, and therefore it does not have high demands on the mounting of the rotor, so that a bearing of the Rotor with plain bearings is possible, as is the subject matter of claim 15. A Hall IC with a digital output signal is preferably used as the galvanomagnetic rotor position sensor, as indicated in the exemplary embodiments, whereby the procedure is expediently so that the magnetization of the! to control the galvanomagnetic sensor serving protrusion I

C area with regard to |

a) the position of the pole gaps and ';

b) the polarity of the poles | substantially coincides with the magnetization of the permanent magnet i '■ rotor in its side opposite to the air gap portion compliance i

it's correct. '

Further details and advantageous developments of the invention U emerge from those described below and shown in the drawing, in no way as

• * D · · I I Il If Il t

I · »· lift 1 * 1

■ · »« t I t t ι ι »

■ · * Il ti I ···

et · «* · _<rtl ·· e · ·

1 I ti I

Restriction of the invention to be understood embodiment ^ as well as from the subclaims. It shows:

Fig. 1 shows an embodiment, here in the form of a two-pulse brushless DC motor for a schematically indicated fan, seen along the line I-I of Fig. 2,

FIG. 2 is a section taken along line 11-11 of FIG Fig. 1,

FIG. 3 is an enlarged illustration, seen along the arrow III in FIG.

Fig. ^Λ a side view of the arrangement according to Fig. 3, shown partially in section,

Fig. 5 shows a development of the rotor magnet of the motor according to

Figs. 1 to 4, 20th

FIG. 6 shows diagrams for explaining FIG. 5, namely

A) the induction (= magnetic flux density), measured along the line A-A of FIG. 5,

B) the induction measured along line C-C of Fig. 5,

C) the output voltage of a Hall IC controlled by the induction according to B),

7 shows a magnetization device for a four- 3® pole rotor, in side view and partially in section,

FIG. 8 is a plan view seen along the line VIII-VIII in FIG. 7,

it I II t IC Il Il II

ti · "ICtI 1" I

. t ■ f <I I I I ·

t I · (C i | · · · i C

ti IVIICII »t

ti ti * ti cc Ii (r

OP III!

9 diagrams of the induced voltage (at A ) and the motor current (at 8), and the influence of the invention on these quantities,

Fig. 10 shows a variant of the magnet: s.ierungsvorrichtung according to FIGS. 7 and 8,

11 shows a schematic diagram of a degaussing

device for demagnetizing insular areas an outer rotor magnet,

■ IO ^{Fi 9-12 eif} he developed representation of a four-pole

Outer rotor magnet with insular areas with

reduced magnetization are provided, and 15

13 shows a plan view of a permanently magnetic rotor designed according to the invention for a flat motor,

20th

In the case of the two-pulse shown in FIGS

commutatorless direct current motor 7 is designated with a Irnenstator 10, the laminated core 11 has in the present embodiment a sheet metal section as it ^{dl 'e DE} - ^p S 23 46 380 describes in detail, in particular

^ ° with regard to the shape of the air gap 23. A trapezoidal rotor magnetization is adapted to this sheet metal section, as will be described in more detail below in connection with FIG. 6A. The motor shown is an external rotor motor; however, the invention can also be used, for example, in the same way in internal rotor motors, as well as in motors with a different number of pulses. In the following (FIG. 13) an exemplary embodiment for a flat motor is also given.

35

I S

J »· ι

I) t ■ t B

{10

The laminated core 11 is held together by three each ; with a thickening 14 provided mandrels 15, 16, 17. It has

a central recess into which a bearing support tube 19 is pressed, which has a fastening at one end flange 20 has. In the grooves 8 and 9 of the laminated core 11; two stator windings 24 and 25 are wrapped, which

. do not overlap each other as shown, thereby

result in a low axial height of the motor and form a winding-free space 21 between them.

At the lower ends of the mandrels 15 to 17 is a ^c chalt-

Board 28 attached from a suitable insulating material. It is provided with a printed circuit with which the connections of the stator windings 24 and 25 are directly connected will. Furthermore, this circuit board carries the entire electrical circuit for controlling the currents in the windings 24 and 25. These card currents are commutated as a function of the rotor position with the aid of a circuit board 28 attached, preferably galvanomagnetic sensor, which is designed here as a Hall IC 30, for example.

Fig. 1 shows chemically two electronic components 31, 32, which are soldered to the circuit board 28.

The stator assembly is fastened by means of its flange 20 with screws 35 to a motor support 36, e.g. Support star of a conventional axial fan for the ventilation of electronic devices, with a fan blade at 33 is indicated. The representations in FIGS. 1 and 2

are enlarged; usually have such axial fans

30th

a prescribed amount of e.g. only 38 mm.

In the bearing support tube 19 is in two plain bearings 37, 38, between which an oil supply felt 34 is arranged, a rotor

shaft 39 supported, which is shown in FIG 35

upper end a rotor bell deep-drawn from soft iron

42 of an outer rotor 40 which is open at the bottom and overlaps the stator 10. Regarding a For a suitable design of the storage, reference is made to GB-PS 1 324 830 of the applicant. In the rotor bell 42 is a continuous ring-shaped rotor magnet 43 arranged. This is indicated in FIGS. 1 and 2 by the letters N (= north pole) and S (= south pole) Way bipolar radially magnetized. The pole gaps 44, 45 of the rotor magnet 43 are narrow.

I.

The Hall IC 30 is arranged in the space between the

two stator windings 24 and 25, so close to the in f

Fig. 2 left pole tips 50 and 51, and in the area between f

the two stator poles 52 and 53. The pole tips 50 and 51 |

enclose, as shown, the left groove 9 and form I;

between them a relatively narrow groove opening for introducing V

of the stator windings 24 and 25. As FIG. 2 clearly shows]

the stator 10 is symmetrical about its center point!

educated. f

I. The Hall IC 30 is fitted into a plastic molding 54, which is attached to the circuit board 28. It is shown in more detail in FIGS. 3 and 4 and has approximately the shape of a Back armchair, so the well-known shape of an upholstered seat

furniture with lateral "ear cheeks", namely a circular base plate 55, from which projections 56 protrude downward into corresponding recesses in the board 28 or another support piece and thereby determine the position of the shaped piece 54. A structure 57 protrudes upward from the base plate 55 and is provided with a recess 58 for receiving the Hall IC 30 and a permanent magnet piece 59 in a form-fitting manner. The latter can be displaced in a guide channel 62 which is provided with a stop 63 at the bottom.

A spacer 64 determines the distance between the underside 35

of the Hall IC 30 from the base plate 55. The two side

Cheeks 65, 66 between which the Hal-IC 30 is arranged are somewhat resilient and thus hold the Hall-IC 30 securely in place: The Hall-IC 30 has wire connections 67 at the bottom, only one of which is shown, and these are at 68 soldered to the conductor tracks of the circuit board 28, whereby the Hall IC 30 and the shaped piece 50 are held on the circuit board 28 at the same time. The permanent magnet piece 59 is fixed by means of an adhesive drop 71. It serves to balance the engine, compare DE-OS 31 11 10

For correct control of the Hall IC 30, a certain magnetic flux density of the rotor magnet 43 is required, i.e. the Upper protruding area 72 of the rotor magnet 43, which protrudes downward over the stator core 11, must be a certain Have a minimum length, e.g. of 5 ... 10 mm. On the opposite side, however, the supernatant area there can be • 73 should be shorter, since a longer overhang area is of no use there, but wastes expensive magnetic material. The one opposite the stator lamination stack 11

Part of the rotor magnet 43 is designated by 70 in FIG. 1.

This different size of the supernatant areas 72 and 73 has the consequence that on the rotor 40 a force 74]

acts in the upward direction (see. Fig. 1), since the rotor-N. ²⁵ magnet 43 always strives to be symmetrical to the Set stator laminated core 11. This upwardly acting force 74 is also dependent on the rotational position, since the air gap 23 according to FIG. 2 is not generally the same, compare the DE - PS 23 46 380, where the air gap shape in detail

Of)

is explained.

When such a motor is used in a fan, this force 74 is acted upon by a counterforce from the fan blades 33 against, and if these forces are roughly equal, considerable and very disruptive axial vibrations can result.

In order to reduce or eliminate this disturbing phenomenon, a special magnetization is used according to the invention of the rotor magnet 43 is used, as is shown by way of example in FIGS. 5 and 6. The following are also indicated other magnetizations that serve the same purpose.

J Fig. 5 shows the rotor magnet 43 in development. the

Pole gaps 44, 45, which can also be beveled, are roughly the same for all rotor areas. Likewise, the magnetization is everywhere around the pole gaps 44, 45 about the same.

The magnetization along the line A-A of FIG. 5, that is to say in the upper part of the motor region 70, is A according to FIG. 6 approximately trapezoidal, i.e. over a range of around 170 ° el. the induction B .. is practically constant and drops steeply in the area of the pole gaps, so that there are steep zero passages at 76 and 77. The same magnetization is found in the upper protruding area 73.

In the lower part of the motor region 70 and in the lower protruding region 72, on the other hand, the magnetization along the ^H line CC is as shown in FIG. 6B.

( ^2Ö The zero crossings at 76 'and 77' are with respect to

Position and shape exactly the same as in 76 and 77, ie the induction B _cc changes here very strongly within a small angle of rotation. This is important for precise switching of the Hall IC 30 as close as possible to these zero crossings 76 'and 77'. (HaVl-ICs have a certain switching asymmetry, ie they do not switch exactly when the polarity of the magnet is reversed. In addition, HaIl-ICs with a digital output signal have a switching hysteresis.

A high steepness of the induction change therefore promotes 5

precise switching at the desired time.)

In the middle area 78 (Fig. 6 B) between the NuIΊ passages 76 ', 77', however, the induction B _{cc is} reduced, for example by 10 to 40 % and preferably by about 20 ... 30 % compared to the maximum value. This reduction has no effect on the output signal U _{30 of} the Hall IC 30, as shown in FIG. 6C, since the sign of the induction does not change here and the Hall IC 30 only knows two switching states at its output, namely high and low. (The invention would also apply to one galvanomagnetic sensor with analog output can be used, since a certain drop in the output signal in the middle area 78 does not interfere there either if the circuit is designed accordingly, e.g. if the analog Hall signal controls a comparator with hysteresis.

This reduction in induction B-- is carried out in each case in an area 79, the limit of which in FIG 80 is designated and which extends approximately to the middle of the rotor magnet 43, that is to say the protruding area

72 and part of the engine area 70 is detected. 20th

Since the force with which a magnet is attracted to a piece of soft iron increases roughly with the square of the magnetic induction, reducing the magnetic induction in areas 79 by approx. 30 %, i.e. to 70 % of the maximum value, roughly halves the magnetic force 74 (0.7 ² = 0.49). In other words, the invention makes the lower protruding region 72 act as if it were much narrower, so that the axial force 74 only

is more small and also when using plain bearings 30

37, 38 can be controlled very well.

The invention also brings - regardless of the question of magnetic pull - an important advantage in the behavior of the motor. Reference is made to FIG. 9 for this purpose. 35

This shows the course of the induced voltage at A)

^u i _nc i » ^{that is to say the} voltage that is induced in the stator windings 24, 25 when the motor is de-energized and may be driving the rotor 40 from the outside. The voltage that would be obtained without the invention is shown with solid lines 82 received, so with uniform magnetization of the whole

Rotor, according to. Fig. 6, A. This voltage is approximately trapezoidal

imt sloping roof.

shaped /. The voltage obtained with the invention is shown with dashed lines 83. This is through the induction reduced in areas 79 is somewhat saddled in the middle, i.e. the roof sections of the trapezoids have Small dents or indentations at the top at 80 or 80 '.

According to Rg.9 B these indentations have 80, 80 ^! an important, very desirable influence on the flow of electricity in the

¹ ^ stator windings 24, 25. Without the invention, the current curve 85 results, which is shown with solid lines and has a strong Einsa'telung at 86, which is undesirable because it reduces the power of the motor 7 and causes an uneven torque. 87 on the other hand shows (in dashed lines) the current curve in the invention, that is, this dip is much weaker there, and the result is a more favorable current curve in which the current rises to less high values during the rise and also shortly before switching off, ν ²⁵ but overall the mean value of the current and thus also the same drive power result, admittedly with less pronounced torque fluctuations, which is very advantageous. The elimination of the undesired current peaks is also favorable for the transistors which switch the currents shown in FIG. 9B, ie these transistors are less heavily loaded.

7 and 8 show an example of a magnetization device 90 which, however, is designed to magnetize a four-pole rotor. (The rotor 40 after the

16

¹ Fig. 1 and 2 is a two-pole rotor).

A laminated core 91 is provided with 4 grooves 32 to 95, is pin-wound in the aine winding 96 as shown, that when current flows through the circumference of the laminated core 91 alternating north and south poles are generated.

The laminated core 91 is cylindrical on the outside, but where the regions 79 are generated with reduced induction are intended, recesses 97 are provided which, as shown, have an approximately cylindrical contour, but each other do not extend to the grooves 92-95. As shown, your Padius corresponds roughly to that of the sheet-metal packet 91, so that the recesses 97 are lens-shaped in cross section are. These recesses 97 are filled with corresponding lenticular copper pieces 98.

The rotor 100 to be magnetized and its rotor magnet 1.01 are indicated schematically in Fig. 7 in the corresponding position. In this position a short direct current pulse is chased through the winding 96 and the magnet 101 then receives the desired magnetization. Eddy currents arise in the lens-shaped copper pieces 98, which displace the magnetic flux lines from these copper pieces and thus support the reduction of the induction in the opposing areas of the rotor magnet 101.

Of course, the device according to FIGS. 7 and 30th

8 can easily be modified for a two-pole rotor, such as

it is shown in Figs.

10 shows a variant of the magnetization device of FIGS. 7 and 8. Identical or equivalent

κ.

Parts as in FIGS. 7 and 8 have the same loading |

i Ϊ

I *

I · t ■ »Jill

I · · · t 1

• · ■ 1} I

Marks as there.

The winding 96 here consists of several turns. No copper pieces are provided in the recesses 97 here, but rather a part 102 in each case The winding 96 is guided around the outside as in FIG. This will be in the recesses 97 Gaig reduces the magnetic induction at Magnetisiercrngsvor- ¹⁰ so that the rotor magnet is less strongly magnetized at the counter opposite locations one hundred and first

Another alternative is shown in Fig. ₅ H ^ d namely a demagnetization device 106 for partial unloading ¹ ^ magnetization of predetermined Preferably insular

shaped areas of a rotor magnet. For this purpose, the rotor magnet is first fully magnetized in a magnetization device, for example in device 90 according to FIGS. 7 and 8, but without the recesses 97, so that a trapezoidal magnetization analogous to FIG. 6A arises everywhere.

The degaussing device 106 according to FIG. 11 has. a magnetic core 107 with four legs 108, of which

\ each carries a winding 109 of the same size, which is parallel

or connected in series and polarized alternately,

so that on the outer circumference of the legs 108 alternately north * and south poles arise, like that in the usual way

is indicated by N (= north pole) and S (= south pole). 30th

According to FIG. 12, this device 106 is mounted opposite the magnetized rotor magnet 110 that it lies approximately opposite the boundary line 111 between the supernatant area 72 and the motor area 70, and then 35

A surge of current is sent through the four windings 108, so that in the magnet 110 four insular areas

112 arise with a well-defined reduced magnetization, some of which are located in the protruding area 72, some in the Motor area 70 and keep a time interval from the pole gaps 113, as well as from the lower one Edge of the rotor magnet 110. In this way one achieves several important advantages:

a) By demagnetizing the magnetize previously Rotor magnet 110 results in a very good overall stable magnetization in the insular areas 112, which changes very little during operation.

b) The control of a Hall IC through the "upper stand area 72" is not impaired.

15th

c) The axial train 74 (Fig. 1) is greatly reduced, so that plain bearings can be used to support the rotor.

d} The desired indentation 80 results (Fig. 9 A) the induced voltage and thus the desired, more uniform current curve.

The invention is not natural with regard to the indentations 80, 80 'and their advantageous effects limited to motors that have a cylindrical air gap and where axial tension can occur.

For example, FIG. 13 shows a four-pole rotor magnet 120

30th

for a flat motor such as, for example, Figs. 1 to 4 or 20 to 22 of US Pat. No. 3,840,761 (US Pat. No. 47 = US Pat. No. 134 eb), to which reference is made to avoid unnecessary lengths. The direction of rotation is shown in Fig. 13;, <referred to it 121, and - about ¹ spiral - Po'llücken sind'mit 122 designates. The course of magnetization along the line AA corresponds to the illustration in Fig. 6A, and the magnetization

TO Ί '· ",'
I.

'''1' ¹ V

it ···· # · J- i

netization loss along the line C-C corresponds to the!, ·

Representation in Fig. 6 C. This is achieved by having |

in each pole 123 an insular area 124 demagnetic |

has been sated. The induced voltage thus receives ||

the shape shown in Fig. 9A with the indentations j

80, 80 *. Naturally, e.g. with the rotor magnet j

120 of Fig. 13 at each pole instead of a large area ti

124 several smaller areas of appropriate size and I.

Magnetize position weaker or - after previous. ; Magnetization - partially demagnetize again. Measure;

The form 'of the induced voltage or the

( desired "smooth" current curve without excessive peaks, "

or valleys. ,

! 5 To achieve this goal one can of course i also corresponding recesses in the rotor magnet. <see. If the rotor magnet is, for example, a so-called rubber magnet, i.e. a mixture of hard ferrite and a s Elastomer, so you can e.g. J

make this magnet less thick or even with |

Holes are provided to create the desired shape of the induced ·· | To maintain tension. In this way you get a very |,

large variety of design options for realizing the invention. In this example, it is by no means ⁽²⁵ necessary - although most advantageous -., That such a motor is controlled by galvanomagnetic Kommutiermittel just as well, the improvement would be the

Form of the induced voltage e.g. for a motor with |

optoelectronic commutation or with high frequency · |

affect commutation. f.

As already mentioned, the invention is equally suitable Also for motors with a different pulse rate. 1. To have to

then correspondingly more galvanomagnetic or other 35

Sensors are provided, but they are controlled by the same control '

• ■ II> l ■ «

• «t ·
■ It Iff

20th

track can be controlled. - Regarding a suitable electronic circuit for use in connection with a Hall IC, e.g., reference is made to DE - OS 31 11 (D 136) should be pointed out.

Claims (16)

PATENT ANWALTRAJBLE TELEFON (O?, 11) l} Efaft48. '. '. . ' . *. . * ΪΡ! ΥΠ = ΝΤΔΝ \ Λ / ΔΙ T 70O0 STUTTGART 1 TELEGRAMS: ABELPAT STJJTTpAtjT J J M «l I_IN IMI NVVML ·! LENBACHSTRASSE 32 POSTSCHECfta ^ lTTeARTT-MOO-TOe ·· r- ^ Ir- ,,, κ, / ^ LJAMC | -> ΛΙΓ3 · ι— ca> ^ K1LLES3ERG) LANCDESGiROKAssEStuttgart 2915076 LJI ML.-MUG <Alt5iNO r REPRESENTATIVE BBM EUROR PATENTAMT EUROPEAN PATENT ATTORNEY Retirement from G 81 19 056 "4 STUTTGART, June 30, 1984 PAPST-MOTOREN GMBH & CO KG ^ nwaltsakte: P61.32D138 / m protection claims 1. Brushless DC motor (internal rotor motor, external rotor motor, Motor with an even air gap, etc.), with a stator (10) and a permanent magnetic rotor (40; _s . 110; 120), S () in particular two-pulse motor with reluctance auxiliary torque, characterized in that that poles of the Rotcrmagneten each have at least one zone (79; 112; 124) with relative to the Induction curve (FIG. 6A) is reduced in the remaining part of these poles Induction (Fig. GB: 78). 2. Motor according to Ansprucu 1, characterized in that it has a has at least a nearly cylindrical air gap (23) (internal rotor motor or external rotor motor) that the poles of the rotor (40) in each case one axial protrusion area (72) with a magnetization for controlling at least one outside the air gap (23) arranged galvanomagnetic sensor (30), in particular % ('of a Hall IC, and that the zones (79; 112) with reduced induction, respectively lie in these overhang areas. 3- engine according to claim 2, characterized in that the zones (79; 112) with reduced induction also in the air gap (23) opposite area of these poles extend. 4. Motor according to claim 2 or 3, characterized in that the zones (79; 112) with reduced induction each at a distance of the adjacent pole gaps (44, 45) are arranged. VTNR: 106941 1111 1. I ··· 1 1 1 · 111 · .1 · * ■ I. 5. Motor according to at least one of claims 2-4, characterized | ^; characterized in that one at both longitudinal ends of the rotor (40) I overhang area (72, 73) is provided, and that the for \ Control of the at least one sensor (30) serving transfer i Stand area (72), measured from the respective adjacent end ; of the laminated stator core (11), a greater axial extent I than the other has over stance area (73). ·. 6. Motor according to at least one of claims 2-5, characterized in that the magnetization (B _n ) of the supernatant used to control the galvanomagnetic sensor (30) : area (72) with regard to a) the position of the pole gaps (44, 45) and ^ b) the polarity of the poles ': essentially with the magnetization of the permanent magnetic Rotor (40) in its the air gap (23) opposite Γ part (70) matches, ' 7. Motor according to claim 3 or 4, characterized in that I roit the zones (79) provided in the air gap region (70) '■ reduced induction not more than 50% of the air gap 5 include area lying rotor magnetic surface. [j 8. Motor according to at least one of the preceding claims, • characterized in that the zones (79; 112; 124) with Reduced induction are formed as at least partially demagnetized areas in the permanent magnet material. 9. Motor according to at least one of claims 1 - 7, characterized in that that the zones (79; 112; 124) with reduced induction are formed as recesses in the Daiiermagnetmaterial ί are. f 10. Motor according to at least one of the preceding claims, there- j characterized in that the zones (112; 124) with reduced I induction in the shape of an island in the respective poles (e.g. 123) are arranged. • t * · ti I I I I I • I • II ' • i · <· 3 * ■ 11. Motor according to claim 10, characterized in that the island-shaped areas are provided approximately in the area of that stator boundary area which corresponds to the galvanomagnetic Sensor (30) controlling rotor area (72) faces. 12. Motor according to at least one of the preceding claims, characterized in that the zones (79; 112) with reduced! ' Induction about 10 ... 90% of the total area of the rotor area interacting with the galvanomagnetic sensor (30) (72) include. 13. Motor according to claim 12, characterized in that the Zones (79; 112) with reduced induction about 40 ... 60% of the total area of this with the galvanomagnetic sensor (30) cooperating rotor areas (72) comprise. 14. Motor according to at least one of claims 2 - 6 "· in which the rotor poles (43) are arranged in a pot-like outer rotor part (42), characterized, that the overhang area (72) for controlling the galvanomagnetic Sensor (30) is on the open side of the cup-like outer rotor part (42). 15. Motor according to at least one of the preceding claims, characterized in that the rotor (40) with sliding bearings (37, f 38) is stored. 16. Motor according to at least one of the preceding claims, characterized in that the permanent magnetic poles of the rotor (40; 110; 120) in their motor-driven area (70) and outside the zones with reduced induction (79; 112; 124) an approximately trapezoidal magnetization (B ^) with narrow gaps (44, 45) of magnetization in the transition area between adjacent poles.