DE102017202546A1 - Stator of an electric motor and electric motor - Google Patents

Abstract

The invention relates to a stator (8) of an electric motor (2) having a stator yoke (14) which has a number of radially directed stator teeth (12) and is provided with a multi-phase rotating field winding arranged on the stator teeth (12) each phase comprises at least one coil which is applied to an insulating bobbin (16) and placed thereon on a stator tooth (12), wherein the or each bobbin (16) at least one radially raised spacer element (18, 34, 36, 40, 42) which projects radially beyond the outer circumference (26) of the stator yoke (14).

Description

The invention relates to a stator of an electric motor, in particular for a steering drive of a motor vehicle, having a stator lamination stack which has a number of radially directed stator teeth and is provided with a rotor phase winding arranged on the stator teeth and comprising several phases.

Today, many motor vehicles have a power steering system that reduces a steering effort needed to operate a steering wheel when steering at a standstill or in the case of low vehicle speeds. The power steering in this case supports a motor vehicle user when steering by the force applied by the motor vehicle user steering force is supported for example with a hydraulic system or with an electric motor.

In electric motor assisted steering (EPS), an electric motor arranged on the mechanics of the steering wheel (steering column, steering gear) supports and superimposes the steering motions of the motor vehicle user with a generated auxiliary power. So-called brushless electric motors (brushless DC motor, BLDC motor) are increasingly used for such electric motor drives (steering drives), in which the wear-prone brush elements of a rigid (mechanical) commutator are replaced by an electronic commutation of the motor current.

Such a brushless electric motor as electric (three-phase) machine has in principle a fixed (stationary) stator with a laminated stator core with a number of, for example, star-shaped stator teeth. The stator teeth carry a rotating electrical field winding in the form of individual (stator) coils or coil windings (phase windings), which in turn are wound from an insulated wire (coil wire). The phase windings are associated with the coil or phase ends of individual (motor) strands or (motor) phases and interconnected in a predetermined manner.

In the case of a brushless electric motor as a three-phase three-phase machine, the stator has three phases and thus at least three phase conductors or phase windings, which are supplied in each case out of phase with electrical current to produce a magnetic rotating field in which a usually provided with permanent magnets rotor or rotor rotates. The phase ends of the phase windings are guided to drive the electric motor via phase connections to an engine electronics. The coil windings of the rotating field winding are in this case interconnected by means of the coil ends in a certain way. The type of interconnection of the coil ends is determined by the winding scheme or the winding structure of the rotating field winding, wherein as a winding scheme, a star connection, a triangular circuit or a combination thereof is common.

Stators for steering drives are usually stored or suspended in the region of its outer circumference in a motor housing of the electric motor. It is desirable that the stator and thus the electric motor designed as possible space-saving and low-weight (constructed). This can be achieved by a cylindrical, the stator teeth encompassing, Statorjoch has the smallest possible radial thickness. However, this leads in the electromotive operation to the fact that the Statorjoch bulges radially inward in the region of the connection points of the stator teeth due to the electromotive forces occurring. This can undesirably lead to a noise and / or vibration of the stator in the engine or drive housing (structure-borne sound), which adversely affect the acoustic properties of the electric motor or the steering drive.

From the DE 10 2009 027 872 A1 It is known that in an electric motor with a motor housing and with a stator arranged therein the electromotive structure-borne noise by means of both sides of the stator and concentric with the motor axis (motor / rotor shaft) arranged decoupling rings from the motor housing to decouple and thereby reduce the noise of the electric motor.

In the assembled state, the decoupling ring rests against the inner wall of the motor housing only with its axial outer ring section remote from the stator, while the outer diameter of the inner ring section of the decoupling ring facing the stator is less than or equal to the outer diameter of the stator. At the decoupling axial wing flaps are formed, which engage in corresponding joining contours of the stator. Hereby and by means of a groove introduced at the outer edge into the outer ring portion or a pin formed thereon, which cooperates in the assembled state with a housing-side mating contour, the decoupling ring is torsionally fixed on the housing side of the housing.

From the DE 10 2015 001 447 A1 a decoupling ring is known, which at its (housing side) outer ring portion a number of radially raised and azimuthally spaced System cam for radial mounting and mounting of the stator relative to the motor housing has.

Disadvantageously, different decoupling rings are necessary for different topologies of the rotating field winding - for example in the case of an 8-pole or 10-pole version of the electric motor - in order to reliably suppress the noise development. Furthermore, such decoupling rings require an additional axial space above and / or below the stator, whereby the size of the electric motor or the steering drive is adversely increased.

Furthermore, there is a tolerance chain with regard to the radial distance between the outer circumference of the stator and / or the decoupling ring and the inner circumference of the motor housing, which has a significant influence on the coaxiality with the rotor, and thus influences the acoustics, disturbance torques and the producible torque of the drive ,

The invention has for its object to provide a stator for an electric motor, with which an acoustically improved coupling is made possible to a motor housing of the electric motor. Furthermore, an electric motor provided with such a stator should be specified with as much noise or structure-borne noise as possible being reduced.

With regard to the stator, the object is achieved with the features of claim 1 and with respect to the electric motor with the features of claim 9 according to the invention. Advantageous embodiments and further developments are the subject of the respective subclaims.

The stator according to the invention comprises a stator yoke with a number of star-shaped and radially inwardly directed stator teeth. The stator teeth are provided with a multi-phase rotating field winding, each phase comprising at least one coil or coil winding (phase winding) having a first and a second coil end, by means of which the respective coil is electrically connected. The coils are in this case arranged in particular as individual coils on a respective stator tooth. Alternatively, double or multiple coils are conceivable, the coil winding is applied to two or more stator teeth.

The stator has, for example, a pole piece which is open radially on the inside, so that the stator teeth can be loaded from a central opening of the stator. The coil ends are connected in the assembled state, for example by means of a front side attachable contact device to the (motor) phases or interconnected.

The stator yoke and the stator teeth of the stator may be formed, for example, in one piece or in one piece or else in several parts or multiple pieces. In one possible embodiment, the stator has, for example, a stator lamination stack with a stator yoke as a cylindrical outer stator component and with a separate stator star as a star-shaped inner stator component with a number of radially outwardly directed stator teeth. The Statorjoch and the stator are in the joining or mounting state of the stator, for example, force or frictionally pressed together. It is also conceivable, for example, an unsegmented embodiment of the stator yoke and the stator teeth (solid stator) or even an embodiment of the stator yoke and the stator teeth as a pole or curb chain.

The coils each have a coil or phase winding, which is wound on an insulating coil carrier (bobbin). The bobbins are, for example, each placed on a stator tooth. In other words, the coil windings forming the coils are each wound around a coil carrier which encompasses the respective stator tooth.

The coil carrier made of an insulating material, in particular of a plastic material, is for example a one-piece or multi-part, approximately rectangular pipe section. The coil carrier preferably has an end face, that means perpendicular to the tooth longitudinal direction, flange collar, between which the existing winding space is limited. The bobbin thus prevents the rotating field winding from sliding down the teeth of the stator. In this case, it is conceivable, for example, that the coil carriers are first wound as individual segments, and then placed on the stator teeth. In other words, the coils are preferably designed as individual, separate components. It is also conceivable, however, that the bobbins are placed on the stator teeth and then wound with the coil winding.

Also conceivable is an embodiment of the bobbin in the manner of a laying ring, which is placed on the front side of the stator teeth. In such an embodiment, in particular two such Verlegeringe are provided as a bobbin, which are placed in pairs on the end faces of the stator lamination. The or each publisher's ring has in each case sleeve-like receptacles for the stator teeth, so that the stator teeth by the recordings of the Verlegeringe essentially each of an insulating coil or Winding bodies are surrounded for guiding the rotating field winding.

The or each bobbin is in this case provided with at least one radially raised spacer, which projects radially beyond the outer circumference of the stator yoke or the stator lamination. As a result, a particularly suitable stator is realized, which allows an acoustically improved coupling to a motor housing of a stator having the electric motor.

In the assembled state, the stator is arranged in a pole-type motor housing of the electric motor, the suspension of the stator in the motor housing being effected by means of the radially upstanding spacer elements. The voltage applied to the motor housing spacers in this case have a significantly reduced contact surface in comparison to the outer periphery of the stator lamination. This leads to a reduction of the noise and thus to a correspondingly improved acoustic behavior of the electric motor. The radially raised spacer elements thus represent an acoustically improved interface of the stator to the motor housing, in particular vibration-isolating or vibration-reducing touch contacts with the motor housing can be realized thereby.

In one possible embodiment with individual bobbins placed on a respective stator tooth, it is conceivable, for example, that not every single bobbin is provided with a radially upstanding spacer element. So it is particularly possible or expedient that only three circumferentially about 120 ° staggered coil body having such a spacer, so that a three-point-like storage or mounting of the stator is realized in the motor housing. As a result, a stable suspension with reduced number of components is realized.

Furthermore, an advantageous functional integration of the stator bearing in the insulating element of the rotating field winding is realized by the combination of the spacer elements with the bobbins. As a result, it is possible, for example, to adapt the or each coil carrier in such a way that, in addition to its main function, it also provides differently pronounced storage possibilities for the insulation and holding of the coil winding. By the spacer elements in this case both a positionally accurate (radial) storage of the stator in the motor housing, as well as a decoupling function with respect to the structure-borne sound occurring during operation possible. As a result, requirements regarding radial tolerance requirements of the stator and / or motor housing are advantageously reduced. Furthermore, a unified decoupling and / or storage of stators of different topologies, that is to say different number and interconnection of the phases, is thus realized, whereby the assembly process of such stators or electric motors is simplified and thus manufacturing costs are reduced.

In the following, with reference to the central stator or motor axis, "axial" in the axial direction and in this context "radial" in the radial direction and "azimuthal" in the circumferential direction of the laminated stator core are understood.

According to an advantageous development, the or each spacer element is arranged on a radially outer flange neck of the bobbin. As a result, a particularly expedient arrangement of the spacer elements is realized, which allow a simple and reliable mounting of the stator in the motor housing.

In one conceivable embodiment, the or each spacer element projects radially beyond the outer circumference of the stator lamination stack in the region of a respective winding head of the coil. As a result, the otherwise unused axial space ("passive space") in the winding heads for storage and mounting of the stator as "active space" in the motor housing can be used. The resulting space optimization is transferred in the sequence advantageous to the use of the entire installation space of the electric motor.

In one possible embodiment, the or each bobbin has a groove-like receptacle, in particular in the region of the radially outer flange collar, in which an elastomeric material is arranged as a spacer element. The spacer is in this case formed, for example, as an elastic O-ring or as a rubber strip. It is also conceivable that the bobbin and the spacer are made, for example, as a common component in a multi-component injection molding process. As a result, an advantageous spacer element is realized, wherein the elasticity of the elastomer material particularly reliably damps or decouples or at least reduces vibrations or vibrations of the stator, that is to say the structure-borne noise occurring during operation, relative to the motor housing.

In an alternative embodiment, the spacer element is made as an additional component from a spring steel, metal or a non-ferrous metal material (Ne metal). For example, it is conceivable or expedient for the O-ring or the strip element, which is seated or can be inserted in the receptacle, to be made of a non-ferrous metal. This is a particularly stable support or suspension for the stator realized, wherein the spacer element is attached to the respective bobbin or fastened. It is also conceivable, for example, that the separate spacer is formed in several pieces or multiple parts.

In an alternative development, the or each spacer is in one piece, that means integrally or monolithically, on the bobbin, in particular on the radially outer flange neck, molded. As a result, a particularly simple and cost-effective production of the spacer element and coil body is ensured as a common component, which translates advantageously in the episode on the assembly costs and assembly costs of the stator or the electric motor.

In a conceivable embodiment, the or each spacer element is designed as a hemispherical bearing block, which is adapted for a press fit with the motor housing. As a result, a particularly stable mounting or mounting of the stator in the motor housing is ensured in the assembled state of the electric motor.

In an equally conceivable alternative embodiment, the or each spacer element is designed as a flexible elastic deformable tab or rib-like spring element whose fixed end is fixed to the radially outer flange neck and its free end in the assembled state spring applied to the motor housing. As a result, on the one hand a damping or vibration-decoupling mounting of the stator is realized in the motor housing. On the other hand, the flexurally elastic configuration advantageously transfers to a reduction of the radial tolerance requirements of the stator and / or of the motor housing.

In one possible embodiment, the or each spring element is oriented transversely to the axial direction of the stator, in particular azimuthally. As a result, an advantageous storage of the stator is realized. In an alternative embodiment, an axial or longitudinal orientation of the spring elements is conceivable. This simplifies the mounting of the stator in the motor housing.

The electric motor according to the invention is particularly suitable and suitable for use in a steering drive of a motor vehicle. For this purpose, the electric motor has a pole-pot-like motor housing, in which a stator and a rotatably mounted rotor are accommodated. In this case, the stator has an in particular approximately (hollow) cylindrical stator yoke, from which a number of stator teeth extend radially inward in a star-shaped manner on the inner peripheral side. In the assembled state, stator or phase windings in the form of coils are applied to the stator laminated core thus formed as a rotating field winding. Between the outer circumference of the Statorjochs (lateral surface) and the inner circumference of the motor housing (housing inner wall) an annular gap region (annular gap, annulus, gap) is formed.

In a preferred embodiment, the stator is mounted or suspended by means of the spacer elements relative to the motor housing to form the annular gap. The spacing elements which overlap the gap area reduce the structure-borne noise transferred from the stator to the motor housing and are designed, for example, as damping, so that vibrations of the stator relative to the motor or drive housing are damped and an associated noise development during operation of the electric motor is reduced or completely prevented. As a result, a particularly low-noise and smooth-running electric motor is realized in a structurally simple and cost-effective manner. Furthermore, the design of the bobbin with a ring gap cross-spacing elements allows a reduction in the axial dimensioning of the stator yoke, whereby the stator itself and the electric motor are particularly space-saving and low-weight executable.

In this context, attenuation of vibrations and / or vibrations of the stator is to be understood in particular as meaning the damping of radially directed forces as a result of the electromotive forces occurring in engine operation on the stator yoke and its deformation occurring thereby.

By the spacer elements thus radial forces are damped during operation of the electric motor or at least reduced. Furthermore, a compensation with respect to the radial clearance in the gap region or annular gap is realized by the spacer elements of the bobbin. This has a particularly advantageous in terms of compensation for different thermal expansion coefficients of the stator and the motor housing. As a result, a possible noise-reduced engine operation of the electric motor is always ensured even with changing operating and / or ambient temperatures.

• 1 in perspektivischer Darstellung einen Elektromotor eines Kraftfahrzeugs mit einem poltopfartigen Motorgehäuse,
• 2 in Draufsicht ausschnittsweise einen in dem Motorgehäuse angeordneten Stator, mit auf den Statorzähnen aufgesetzten Spulenkörpern, welche jeweils mindestens ein Abstandselement aufweisen,
• 3 in Schnittdarstellung mit Blick auf die Schnittebene den Spulenkörper entlang der Line III-III gemäß 2, und
• 4 bis 7 in schematischer Schnittdarstellung unterschiedliche Ausführungsformen des Abstandselements des Spulenkörpers.

Embodiments of the invention are explained in more detail with reference to a drawing. Show:

• 1 in a perspective view of an electric motor of a motor vehicle with a pole-type motor housing,
• 2 In plan view, a detail of a stator arranged in the motor housing, with placed on the stator teeth bobbins, each having at least one spacer element,
• 3 in a sectional view with a view of the cutting plane of the bobbin along the line III-III according to 2 , and
• 4 to 7 in a schematic sectional view of different embodiments of the spacer element of the bobbin.

Corresponding parts and sizes are always provided with the same reference numerals in all figures.

1 shows an electric motor 2 a motor vehicle, in particular for an electromotive steering drive, with a pole-type motor housing 4 , Recognizable interspersed in the axial direction A running motor shaft 6 the motor housing 4 , On the motor shaft 6 is not recognizable rotor arranged waveproof, which rotates in a stator 8th of the electric motor 2 is stored.

The in 2 partial illustrated stator 8th has a stator core 10 with radially inward, that means along a radial direction R oriented, stator teeth (pole cores) 12 on. The stator teeth 12 are polschuhseitig, that means radially inside or freiendseitig, open, so not connected to each other. Radially on the outside, that means at the tooth ends facing away from the pole shoe, are the stator teeth 12 to an annular, the stator teeth 12 encompassing, Statorjoch 14 of stator laminated core 10 tethered.

In the assembled state, the in 2 invisible rotating field or coil windings around the stator teeth 12 of the stator 8th placed. The windings are used as coils on insulating winding carriers or bobbins 16 wrapped and with these on the stator teeth 12 placed. Each of the frame-like bobbin 16 in this case carries a (single) coil or coil winding in the assembled state as part of the stator or rotating field winding.

In the assembled state of the electric motor 2 there is a suspension or storage of the stator 10 inside the motor housing 4 by means of radially projecting spacers 18 the bobbin 16 , The 2 shows in plan view fragmentary with the bobbin 16 equipped stator 10 in the pole-type motor housing 4 of the electric motor 2 , The bobbin 16 in this case has a radially inner flange neck 20 and one to the motor housing 4 oriented, radially outside, flange collar 22 on. The flange collar 20 and 22 limit an interposed winding area 24 on which the coil windings of a coil are arranged in the assembled state. At the flange collar 22 is in each case at least one radially raised spacer element 18 arranged, which an outer circumference 26 of stator laminated core 10 or the Stator yoke 14 protrudes radially.

In the assembled state of the electric motor 2 Preferably, a vibration or vibration decoupling of the housing-internal stator 8th from the motor housing 4 over the spacers 18 , in which in the assembled state statorfesten bobbin 16 or flange collar 22 and a housing-fixed inner wall (housing inner wall, inner circumference) 28 by means of an annular gap region or annular gap (annular space, gap) 30 separated from each other and only via the spacer elements 18 are in contact with each other.

In other words, between the outer circumference (lateral surface) 26 of the Stator yoke 14 and the inner circumference 28 of the motor housing 4 the annular gap 30 educated. Through the spacer elements 18 the bobbin 16 is the stator 8th thus opposite the motor housing 4 stored or suspended or supported. In the area of spacers 18 is in the outer circumference 26 of the Stator yoke 14 in each case an axially extending stator groove 32 brought in. The spacer element 18 overlaps both the gap area or annular gap 30 as well as the through the stator 32 Exempted area and is free endseitig on the housing inner wall 28 of the motor housing 4 at.

Like in the 3 shown, the bobbin 16 here spacers 18 on which axially above and below the stator lamination 10 radially its outer periphery 26 up stand. This means that the spacers 18 essentially in the area of a respective winding head of an applied coil on the flange collar 22 are arranged. In the in 3 illustrated embodiment, the spacers 18 essentially as integrally formed, radial extending projections 34 of the flange collar 22 educated.

The following are based on the 4 to 7 different embodiments of the spacer elements 18 explained in more detail with reference to schematic representations.

In the in 4 illustrated embodiment, the spacers 16 each by an approximately cylindrical rubber strip 36 formed, which in a respective, groove-like, recording 38 of the flange collar 22 is included. The rubber strip 36 is made of an elastomeric material and oriented along its strip longitudinal direction along the Statorumfangs (Azimuthalrichtung). As in the sectional view of 4 is comparatively clear, the diameter of the rubber strip 36 in this case dimensioned such that the rubber strip 36 the annular gap 30 overlaps and on the inner wall 28 of the motor housing 4 at least in sections. Due to the elasticity of the rubber strip 36 Here is an additional attenuation of occurring vibrations and / or vibrations of the stator 8th in the direction of the motor housing 4 realized. This is a particularly quiet operation of the electric motor 2 guaranteed.

In the embodiment of 5 are the spacers 18 as hemispherical or domed, radial, elevations in the form of plant socks 40 educated. The plant socks 40 are here in one piece, so one-piece or monolithic, on the flange collar 22 formed. The plant socks 40 are in particular for a press fit with the motor housing 4 set up so that a particularly secure suspension or storage of the stator 8th in the motor housing 4 is realized.

In the 6 and 7 is an embodiment of the spacer elements 18 in the form of elastically deformable tab or rib-like spring elements 42 shown. The spring elements 42 have this one on the flange collar 22 fixed end 44 and a standing free-end 46 on. The free ends 46 the spring elements 42 in this case spring against the housing inner wall 28 of the motor housing 4 at. As a result, on the one hand, a damping or vibration-decoupling mounting of the stator 8th in the motor housing 4 realized. Furthermore, the flexurally elastic configuration advantageously transfers to a reduction of the radial tolerance requirements of the stator 8th and / or the motor housing 4 , reducing the assembly costs of the electric motor 2 be reduced.

In the in 6 The embodiment shown are the spring elements 42 along the axial direction A of the stator 8th or the electric motor 2 oriented. The free ends 46 the spring elements 42 are each of the stator lamination 10 Oriented away. This will cause the assembly of the stator 8th in the motor housing 4 simplified.

The embodiment of 7 shows a transverse or azimuthal directional arrangement of the spring elements 42 , In other words, the respective longitudinal direction is between the fixed end 44 and the free 46 the spring elements 42 along the circumferential direction of the stator lamination 25 oriented.

The invention is not limited to the embodiments described above. Rather, other variants of the invention can be derived therefrom by the person skilled in the art without departing from the subject matter of the invention. In particular, all the individual features described in connection with the exemplary embodiments can also be combined with one another in other ways, without departing from the subject matter of the invention.

LIST OF REFERENCE NUMBERS

2

electric motor

4

motor housing

6

motor shaft

8th

stator

10

stator lamination

12

stator tooth

14

stator yoke

16

bobbins

18

spacer

20.22

flange collar

24

winding area

26

Outer circumferential / lateral surface

28

Inner wall / casing inner wall / inner periphery

30

annular gap

32

stator

34

extension

36

rubber strip

38

admission

40

conditioning cam

42

spring element

44

fixed end

46

free end

A

axially

R

radial direction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009027872 A1 [0007]
• DE 102015001447 A1 [0009]

Claims (10)

Stator (8) of an electric motor (2) having a stator yoke (14) which has a number of radially directed stator teeth (12) and is provided with a multi-phase rotating field winding arranged on the stator teeth (12), wherein each phase comprises at least one coil which is applied to an insulating bobbin (16) and placed thereon with a stator tooth (12), - Wherein the or each bobbin (16) at least one radially raised spacer element (18, 34, 36, 40, 42) which projects radially beyond the outer periphery (26) of the stator yoke (14). Stator (8) after Claim 1 , characterized in that the or each spacer element (18, 34, 36, 40, 42) on a radially outer side flange collar (22) of the bobbin (16) is arranged. Stator (8) after Claim 1 or 2 , characterized in that the or each spacer element (18, 34, 36, 40, 42) projects radially beyond the outer periphery (26) of the stator yoke (14) in the region of a respective winding head of the coil. Stator (8) after one of Claims 1 to 3 , characterized in that the or each spacer element (18, 36) is made of an elastomeric material and in a groove-like receptacle (38) of the bobbin (16), in particular the radially outer flange flange (22) is arranged. Stator (8) after one of Claims 1 to 3 , characterized in that the or each spacer element (18, 34, 40, 42) integrally formed on the bobbin (16), in particular on the radially outer side flange collar (22) is integrally formed. Stator (8) after Claim 5 , characterized in that the or each spacer element (18) as a hemispherical bearing block (40) is formed, which is adapted for a press fit with a motor housing (4). Stator (8) after Claim 5 , characterized in that the or each spacer element (18) is designed as a resiliently deformable strap-like or rib-like spring element (42). Stator (8) after Claim 7 , characterized in that the spring element (42) is oriented transversely to an axial direction (A). Electric motor (2), in particular for a steering drive of a motor vehicle, with a motor housing (4) and with a stator (8) arranged therein according to one of Claims 1 to 8th , Electric motor (2) after Claim 9 wherein the or each spacer element (18, 34, 36, 40, 42) rests against an inner wall (28) between a stator yoke (14) and the motor housing (4) to form an annular gap (30).

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