Stator of an electric motor and electric motor

Abstract

The invention relates to a stator (5) of an electric motor (1), having a number of radially directed stator teeth (6) on which respectively an insulating coil carrier (11) for coils of a multiphase rotating field winding is arranged or can be arranged, wherein the stator teeth (6) are connected to one another at an outer circumference (U A ) on the yoke side in the case of a stator slot (7), wherein between adjacent stator teeth (6) respectively a slot gap (10) is formed at an inner circumference (U I ) of the pole shoe, and wherein at the inner circumference (U I ) of the pole shoe side of the stator teeth (6) a reinforcement is provided in the form of a reinforcing element (14) which is guided into one slot gap (or each slot gap (10).

Description

TECHNICAL FIELD

[0001] The invention relates to a stator for an electric motor of a steering drive, in particular for a motor vehicle, having a number of radially directed stator teeth on which respectively an insulated coil carrier for coils of a multiphase rotating field winding is arranged. The invention also relates to an electric motor having such a stator. BACKGROUND

[0002] Such a stator is used in particular in brushless electric motors (brushless DC motors, BLDC motors), in which the easily wearing brush elements of a rigid (mechanical) commutator are replaced by an electronic commutation of the motor current. Such electric motors are for example used in electric motor type power assisted steering (EPS: Electric Power Steering, EPAS: Electric Power Assisted Steering) of a motor vehicle to support the manually steering movement of a motor vehicle user with an electrically generated assistance force.

[0003] The (stationary) stator used in electric motors as (three-phase) machines in principle has a stator lamination stack having a number of stator teeth arranged in a star. The stator teeth carry rotating field electrical windings in the form of single (stator) coils or coil windings (phase windings), which are in turn wound from insulated wire material (coil wire material). The phase windings are assigned to individual, usually three (motor) phases with their coil ends or phase ends and are interconnected in a predetermined manner.

[0004] The typical three-phase (phase windings) are respectively phase-shifted loaded with current in order to generate a rotating magnetic field in which a rotor (mover) provided with permanent magnets rotates. The phase ends of the phase windings are guided via phase terminals to motor electronics for driving the electric motor. The coils of the rotating field windings are interconnected in a specific manner by means of their coil ends. The type of interconnection of the coil ends is determined by the winding scheme or winding structure of the rotating field windings, wherein as winding schemes star connection, delta connection or combinations thereof are common.

[0005] The stator for a steering drive is usually supported or suspended in the peripheral region in the motor housing of the electric motor. It is desirable here that the stator and thus the electric motor is implemented (built) as space-saving and lightweight as possible and as low-noise as possible in operation. Here, the stator can be implemented with a cylindrical stator yoke that surrounds the stator teeth and with a decoupling ring arranged on the end side in order to suppress noise generation.

[0006] The stator yoke and the stator teeth can be formed in one piece or in one body, for example, or else in multiple pieces or in multiple bodies. In one possible embodiment, the stator has, for example, a stator lamination stack with a stator yoke as a cylindrical outer stator component and a separate stator star as a star-shaped inner stator component with several radially outwardly directed stator teeth. In the engaged or assembled state of the stator, the stator yoke and the stator star are pressed against one another, for example, in a force-locked or friction-locked manner. A non-segmented design of the stator yoke and the stator teeth (solid stator), for example, or else a segmented design of the stator yoke and the stator teeth as a pole chain or an armoured chain is likewise conceivable.

[0007] The stator of an electric motor, in particular of a steering motor of a motor vehicle, known from DE 10 2017 202 546 A1 comprises a stator yoke with several stator teeth arranged in a star and directed radially inward, which are provided with coils of a multiphase rotating field winding. The coils can be arranged on the stator teeth as single coils, respectively, or can be applied on two or more stator teeth as double coils or multiple coils. The stator teeth are connected to one another on the outer diameter (outer circumference) of the yoke side to form a magnetic return, while the radially inner side of the pole shoes is open for reasons of electromagnetic flux. To this end, the stator teeth are spaced apart from one another on the free end of the inner diameter (inner circumference) of the stator on the rotor side of the stator to form a gap for avoiding magnetic short circuits. The coils are wound on an insulated coil carrier (winding body or winding carrier), and the wound coil carrier is mounted on the stator teeth. In the assembled state, the coil ends are connected to one another, for example, by means of contact means which can be mounted on the end side.

[0008] Due to the operation-related electromagnetic excitation of the stator and due to the formation of the necessary gap at the free ends of the stator teeth, which lack a connection on the inner circumference of the stator, the radial stiffness thereof is very low, and thus the radial deformation thereof is particularly great. In particular, a stator having twelve stator teeth and twelve stator slots and, for example, five magnetic poles is deformed particularly strongly due to the opposing magnetic forces resulting therefrom. This deformation is usually transmitted to the motor housing surrounding the stator of the electric motor. This in turn leads to a higher acoustic level in the example mentioned above with 12 stator slots and 5 magnetic poles of the 10th (motor) order on the stator side and thus to the generation of undesirable noise in the operation of the electric motor. SUMMARY

[0009] It is the task of the present invention to specify a particularly suitable stator for an electric motor, wherein better acoustic properties should be achieved in the electric operation. Furthermore, an electric motor provided with such a stator should be specified which generates as little noise as possible.

[0010] According to the application, the tasks mentioned are solved with the features of claim 1 in relation to the stator and with the features of claim 10 in relation to the electric motor. Advantageous design and refinement proposals are the subject of the respective dependent claims.

[0011] The stator has a number of radially directed stator teeth on which coil carriers (winding bodies or winding carriers) for a multiphase rotating field winding are arranged or can be arranged. The stator teeth are connected to one another at the outer circumference (stator outside diameter) on the yoke side in the case of the formation of stator slots. At the inner circumference (stator inside diameter) on the pole shoe side, where the slot gaps are formed between adjacent stator teeth, respectively, a reinforcement is provided in the form of a reinforcing element which is guided into one or each slot gap. The stator is particularly suitable or is provided for use as an electric motor as a steering drive of a motor vehicle.

[0012] The coil carriers preferably have a flange collar on the end side, i.e. directed perpendicular to the tooth longitudinal direction, between which the winding space present is limited. The coil carriers made of insulating material, in particular of plastic material, are preferably two-part. The coil carriers expediently have two half-shell-shaped coil carrier parts which have axially extending coil carrier sections which flank the respective stator tooth on both sides. In other words, the coil carrier parts are approximately U-shaped, wherein the legs of the U form the coil carrier sections between which the axial section of the respective stator tooth is accommodated.

[0013] The respective stator tooth is expediently equipped with a coil carrier, in particular with two coil carrier parts, and is wound with a respective coil. Subsequently, the stator teeth wound in this way are connected to one another on the yoke side. In other words, the coil carriers are first arranged on the stator teeth which are wound with the respective coils as separate sections.

[0014] The thought underlying the application is that, when sufficient stator radial stiffness is also established in the region of the free ends of the pole shoe side of the stator teeth, better acoustic properties can be achieved in the electric operation. This can be achieved, as is acknowledged, by filling the slot gaps between the free ends of the pole shoe side of the stator teeth, for example also by plastic coating of the stator, so that the plastic coating extends into the slot gaps and thus establishes a connection on the inner circumference of the stator.

[0015] The reinforcement of the stator at the inner circumference (stator inside diameter) of the pole shoe side of the stator is expediently achieved in that the coil carriers contact within the respective stator slot in the region of the slot gap on the respective pole shoe side. To this end, it is expediently provided that a reinforcing element is arranged in the slot gap formed between adjacent stator teeth at the inner circumference on the pole shoe side. This is preferably achieved in that the coil carrier has a coil carrier protrusion which is guided into the slot gap as the reinforcing element.

[0016] It is particularly preferred that the coil carrier projection as a reinforcing element, which is guided into the slot gap on the pole shoe side, is formed only on one of the two coil carrier sections of the respective coil carrier part. Thereby, the coil carrier part can advantageously be manufactured (provided) as a generic piece. In a suitable manner, two axially offset coil carrier projections of the coil carrier part of an adjacent stator tooth are guided into the slot gap. In other words, two preferably generic coil carrier parts are arranged on the stator tooth in a rotation of 180° relative to each other from different axial directions and thus jointly form the stator carrier of the respective stator tooth.

[0017] In an advantageous design, the reinforcement of the stator at the inner circumference (stator inner diameter) of the pole shoe side of the stator is thus achieved by the coil carrier being modified in such a way that at least one coil carrier extending radially within the stator slot to the slot gap has a projection guided into the slot gap, which is used as a reinforcing element in the slot gap. The reinforcing element, which is preferably formed on the coil carrier and is inserted into the slot gap of a single, multiple or all slot gaps, thus forms the reinforcement of the stator in a particularly advantageous manner and method, so that the stator has a particularly high (great) radial stiffness.

[0018] In order to avoid magnetic short circuits, the reinforcing element consists of a non-magnetic material, in particular a plastic material. The reinforcing element is preferably clamped in the slot gap between the stator teeth which form the flanks of the slot gap and which form the respective stator slot.

[0019] According to a particularly preferred refinement, the coil carrier has corresponding abutment contours in the region of the slot gap within the stator slot. The abutment contours or abutment faces provided or formed therefrom are designed / dimensioned in a suitable manner such that they at least partially overlap. The abutment contours or the abutment faces thereof can extend radially straight therefor. Alternatively, a keyway contour is provided, which is introduced into the coil carrier in the region of the slot gap, preferably radially directly adjacent to the slot gap within the stator slot, on one side as a slot and on the other side as a tongue or tab as a key which is embedded in the slot. The contour can also be dovetail-shaped, for example.

[0020] The electric motor according to the application is particularly suitable and intended for use in a steering drive of a motor vehicle. The electric motor has a pot-shaped motor housing in which a stator reinforced on the pole shoe side and a rotor rotatably supported relative to the stator are accommodated. The stator has several stator teeth extending radially inward in a star shape between which stator slots are formed in which coils of a stator winding or rotating field winding are accommodated. BRIEF DESCRIPTION OF DRAWINGS

[0021] Embodiments of the application will be explained in more detail below with reference to the drawings. Therein:

[0022] Figure 1 A perspective view of an electric motor in a motor vehicle is shown, the electric motor having a canister-shaped motor housing;

[0023] Figure 2 shows a top view of a stator arranged in the motor housing and reinforced on the pole shoe side, the stator having stator slots between stator teeth on which coil carriers are mounted;

[0024] Figure 3a shows a truncated section along... Figure 1 The cross-sectional view of line III-III shows that the stator slots between adjacent stator teeth have slots on the pole shoe side, and there are reinforcing elements introduced into the slots on the inner circumference of the pole shoe side as the stator reinforcement.

[0025] Figure 3b, based on the illustration in Figure 3a, shows a coil carrier protrusion extending into the slot on the pole shoe side as a reinforcing element, which partially overlaps with a section of the coil carrier of the adjacent stator tooth.

[0026] Figure 3c illustrates, based on the illustration in Figure 3b, the keyway profile of the coil carrier section as the overlapping portion within the slot region on the pole shoe side; and

[0027] Figure 4 A perspective view shows a coil carrier consisting of half-shells of the same type that serve as coil carrier parts. When viewed from their yoke sections (tooth ends on the yoke side), they have reinforcing elements on the pole shoe side on different sides of the stator teeth along the stator circumference.

[0028] Figure 5 Shown in perspective according to Figure 4 The two-piece (double-shell) coil carrier has coil carrier sections with mutually facing free ends; and

[0029] Figure 6 according to Figure 4 The illustration shows a two-piece (double-shell) coil carrier that, when viewed from the pole shoe (the tooth tip on the pole shoe side) of the stator teeth, has the same coil carrier portion.

[0030] Corresponding parts are given the same reference numerals in all the accompanying drawings. Detailed Implementation

[0031] Figure 1 An electric motor 1 for a motor vehicle is shown, particularly an electric motor for an electric motor-driven steering system, the electric motor having a canister-shaped motor housing 2. A motor shaft 3 extending in the axial direction A can be seen passing through the motor housing 2. A rotor 4 (Fig. 2), for example equipped with permanent magnets, is fixedly arranged on the motor shaft 3 relative to the shaft, and the rotor is rotatably supported in the stator 5 (Fig. 2) of the electric motor 1.

[0032] The stator 5, which surrounds the rotor 4 and is shown in Fig. 2 in a sectional view, has a number of stator teeth 6 which are oriented in the radial direction R, i.e. point radially inwards, between which stator teeth stator slots 7 are formed. The stator teeth 6 are preferably embodied as axially (in the axial direction A) extending segmented lamination stacks and are connected to one another on their side facing the outer circumference (outer diameter) U of the motor housing 2 A The stator teeth 6 are connected to one another on their side facing outwards, i.e. radially on the outside, for example by means of welding, to form a stator yoke 8. Here, advantageously, a particularly high filling factor of the coil winding in the stator slots 7 is achieved.

[0033] In the assembled state, the not visible in Fig. 2 rotating field winding or coil winding is laid around the stator teeth 6 of the stator 5. The winding is wound as a coil on an insulated coil carrier or winding carrier 11 which is arranged on the stator teeth 6. Each coil carrier 11 here carries in the assembled state a (single) coil or coil winding as part of the stator or rotating field winding. The segmented stator teeth 6 on which the coil carriers 11 are plugged in form the pole sections of the stator 5. The coil carriers or winding carriers 11 are arranged in a suitable manner on the stator teeth 6 and the coil winding is subsequently applied. The stator teeth 6 which have been wound in this way are then connected to one another on the yoke side to form the stator 5.

[0034] The respective coil carrier 11 has a flange collar 12 on the yoke side and a flange collar 13 on the pole shoe side. It can be seen that these pole shoe side flange collars 13 of the coil carriers 11 come into contact in the region of the pole shoes 14 of the stator 5. By this, a reinforcement of the stator 5 on the pole shoe side is achieved. As a result of the reinforcement of the stator 5 at its (pole shoe side) inner circumference (inner diameter) U I the radial stiffness of the stator 5 is increased and on this basis the acoustic level of the electric motor 1 which is thus in particular low noise is improved.

[0035] As can be seen comparatively clearly from Figs. 3a to 3c, the stator 5 is open at its inner circumference (inner diameter) U I on the pole shoe side. For reasons of electromagnetic flux, in the region of the tooth free ends 9 on the radially inner side between the stator teeth 6, in the pole shoe side respectively in the respective stator slot 7, a slot gap 10 is formed.

[0036] In the embodiment shown in Fig. 3a, a reinforcing element 14 is inserted into the slot gap 10. The stator slot 7 between two adjacent stator teeth 6 shown in a sectional view can be seen, on which stator teeth respectively a coil carrier 11 is arranged, of which only the coil carrier section 11a on the one side and the coil carrier section 11b on the other side of the stator slot 11 are shown. In other words, the coil carrier section 11a of the left coil carrier 11 in Fig. 3a and the coil carrier section 11b of the right coil carrier 11 in Fig. 3a are disposed within the stator slot 7. These coil carrier sections 11a, 11b are guided radially towards the reinforcing element 14 and lie against the reinforcing element.

[0037] The corresponding reinforcing elements 14 can be similarly inserted into the slots 10 on all other pole shoe sides of the stator 5. To avoid electromagnetic short circuits, the additional material formed by the respective reinforcing elements 14 is selected from non-magnetic materials, such as plastic. The reinforcing elements 14 are sandwiched in the respective slots 10 between the stator teeth 6 that form the slot side wings and the respective stator slots 7.

[0038] In the embodiments shown in Figures 3b and 3c, the inner circumference (stator inner diameter) U of the stator 5 on its pole shoe side I The reinforcement at the stator 5 is established by means of coil carriers 11. For this purpose, a coil carrier protrusion 15 of one of the two coil carriers 11 extends radially into the slot 10 within its respective stator slot 7. The coil carrier protrusion 15 extending into the slot 10 thus forms a reinforcing element 14. The reinforcing element 14 inserted into the slot 10 forms a reinforcement of the stator 5 in a particularly effective manner, and thus greatly improves the radial stiffness of the stator. For this purpose, the coil carriers 11 have corresponding abutment contours 16 or abutment surfaces provided by these abutment contours in the region of the slot 10 within the stator slot 7. The abutment contours 16 are designed such that they overlap, preferably axially, or for example, only partially overlap.

[0039] In the embodiment according to Figure 3b, the contour 16 extends in a straight line. This embodiment is particularly simple and can be manufactured inexpensively.

[0040] In the embodiment according to FIG. 3c, the abutment contour 16 forms a keyway contour. These abutment contours are all disposed adjacent to the slot 10 within the stator slot 7. Here, a slot 16a is introduced on one of the coil carrier sections, specifically on the coil carrier section 11a of the left coil carrier 11 in FIG. 3c, while on the other, specifically on the coil carrier section 11b of the right coil carrier 11 in FIG. 3c, a tenon or protrusion 16b is formed as a key and embedded in the slot 16a. This embodiment is characterized by particularly high rigidity.

[0041] In the two embodiments according to Figures 3b and 3c, overlapping portions are provided to achieve elastic compression of the coil carrier material. The coil carrier protrusions 15, guided into or recessed into their respective slots 10 as reinforcing elements 14, are clamped between adjacent stator teeth 6. This provides particularly effective reinforcement of the stator 5. Furthermore, it ensures that the coil carrier 11 does not deviate from the direction of the stator winding due to the force applied during the compression process. By compressing the material, a preload is generated in the system, allowing the pressing force to be transmitted.

[0042] Figures 4 to 6A perspective view of the coil carrier 11 composed of two identical half-shells as coil carrier portions 11c, 11d is shown, viewed from the yoke section 8a of the stator yoke 8 ( Figure 4 ) or viewed from the pole shoe 17 of the stator tooth 6 at the tooth free end 9 ( Figure 6 ), the coil carrier portions have a coil carrier projection 15 on the pole shoe side on different sides of the stator tooth 6 in the circumferential direction U of the stator 5 as a reinforcing element 14.

[0043] It can be seen that the coil carrier projection 15 on the pole shoe side of the lower coil carrier portion 11d in Figures 4 to 6 extends approximately or exactly over the lower half of the stator tooth 6 in the axial direction A. The coil carrier projection 15 on the pole shoe side of the upper coil carrier portion 11c extends approximately or exactly over the upper half of the stator tooth 6 on the side which is visible in Figure 4 and Figure 5 and is obscured in Figure 6 .

[0044] As can be seen comparatively clearly in Figure 5 , the coil carrier projection 15 as a reinforcing element 14 which is guided into the slot gap 10 on the pole shoe side is only formed onto one of the two coil carrier sections 11a of the respective coil carrier portion 11c, 11d. The coil carrier portions 11c, 11d which are embodied as a general part are arranged relative to one another at 180°, so that the section free ends 18c, 18d of the coil carrier sections 11a of the U-shaped coil carrier portions 11c and 11d face one another.

[0045] In the engaged state of the stator tooth 6 and the installed coil carrier 11, thus of the two axially offset coil carrier projections 15 of the coil carrier portions 11c, 11d of the respectively adjacent stator tooth 6, the respective coil carrier projection 15 is guided into the slot gap 10 on the pole shoe side. Here, the respective coil carrier projection 15 rests on that coil carrier section 11b of the coil carrier 11 of the adjacent stator tooth 6 which does not have a coil carrier projection 15. Thus, the coil carriers 11 of the adjacent stator teeth 6 engage within the slot gap 10 in a stepped or comb-like manner, i.e. they rest on one another in the axial direction A with their resting contour (resting surface) 16 in a stepped manner and are preferably pressed against one another. In other words, in the process of engaging the stator teeth 6 to form the stator 5, the coil carriers 11 press against one another in the region of their slot gap side coil carrier projections 15.

[0046] In summary, the invention relates to a stator 5 of an electric motor 1, in particular as a steering drive of a motor vehicle, having a number of radially directed stator teeth 6 on which an insulated coil carrier 11 for coils of a multiphase rotating field winding is respectively arranged, wherein the stator teeth 6 are connected to one another at an outer circumference U A of the yoke section in the case of the formation of a stator slot 7 and wherein a reinforcement is provided on an inner circumference U I of the pole shoe section of the stator teeth 6. The reinforcement element 14 is guided into one or each slot gap 10 in a suitable manner, which is formed by the coil carrier protrusion 15.

[0047] The invention claimed is not limited to the embodiments described above. Rather, other variants of the invention can also be derived by the person skilled in the art within the scope of the claims disclosed, without departing from the subject matter of the invention. Furthermore, all individual features described in connection with the different embodiments can also be combined in other ways within the scope of the claims disclosed, without departing from the subject matter of the invention claimed.

[0048] Furthermore, the solution described can be used not only in the application cases specifically illustrated, but also in similar embodiments for other motor vehicle applications, such as in vehicle door and tailgate systems, window lifters, vehicle locks, adjustable seats and interior space systems, as well as in electric drives, control units, sensors and their components in the vehicle interior.

[0049] List of reference signs

[0050] 1 electric motor

[0051] 2 motor housing

[0052] 3 motor shaft

[0053] 4 rotor

[0054] 5 stator

[0055] 6 stator tooth

[0056] 7 stator slot

[0057] 8 stator yoke

[0058] 8a yoke section

[0059] 9 tooth free end

[0060] 10 slot gap

[0061] 11 coil / winding carrier

[0062] 11a, b coil carrier section

[0063] 11c, d coil carrier part

[0064] 12 flange collar (yoke side)

[0065] 13 flange collar (pole piece side)

[0066] 14 reinforcement element

[0067] 15 coil carrier protrusion

[0068] 16 abutment contour / abutment surface

[0069] 16a slot

[0070] 16b lug / tongue / key

[0071] 17 pole piece

[0072] 18c,d segment free end

[0073] A axial direction

[0074] R radial direction

[0075] U circumferential direction

[0076] U A outer circumference / outer diameter (yoke side)

[0077] U I inner circumference / inner diameter (pole piece side)

Claims

1. A stator (5) of an electric motor (1), the stator having a plurality of radially oriented stator teeth (6), on which insulated coil carriers (11) for multiphase rotating field windings are respectively mounted. -in, The stator teeth (6) form stator slots (7) on the outer periphery of the yoke side (U). A ) are connected to each other at each point. -Among them, in the inner circumference of the pole shoe (U I At position ), slots (10) are formed between adjacent stator teeth (6), and -In which, on the inner circumference (U) of the pole shoe side of the stator tooth (6) I A reinforcing portion is provided at the location of the reinforcing element (14) which is guided into the slot (10). -The coil carrier (11) has two semi-shell-shaped coil carrier portions (11c, 11d), each coil carrier portion having axially extending coil carrier sections (11a, 11b) forming flanks on both sides of its respective stator tooth (6). -In this case, the coil carrier protrusion (15) that serves as a reinforcing element (14) in the slot (10) on the pole shoe side is formed on only one of the two coil carrier sections (11a, 11b) of the respective coil carrier portions (11c, 11d). -In this case, two axially staggered coil carrier protrusions (15) of the coil carrier portions (11c, 11d) of adjacent stator teeth (6) are guided into the slot (10), wherein the coil carriers (11) of adjacent stator teeth (6) are engaged in a stepped or comb-like manner within the slot (10).

2. The stator (5) according to claim 1, Its features are, The reinforcing element (14) is made of a non-magnetic material.

3. The stator (5) according to claim 1 or 2, Its features are, It has a keyway profile (16a, 16b) between adjacent stator teeth (6) in the region of the slot (10).

4. The stator (5) according to claim 1, Its features are, The inner circumference (U) on the pole shoe side of the stator tooth (6) I A reinforcing part is provided at the location in the form of a reinforcing element (14) that is guided into each slot (10).

5. The stator (5) according to claim 2, Its features are, The reinforcing element (14) is made of plastic.

6. An electric motor (1) having a motor housing (2) and a stator (5) arranged in the motor housing according to any one of claims 1 to 5.

7. The electric motor (1) according to claim 6, Its features are, The electric motor is an electric motor used in the steering drive device of a motor vehicle.

Images