Stators for electric motors

Abstract

The invention relates to a stator (1) for an electric motor (16), the stator having stator teeth (3) arranged in a star shape and a stator base body (2) with a stator yoke (), a certain number of axial grooves (6) being arranged on the outer circumference (5) of the stator base body, and coupling elements (7) radially protruding from the stator base body (2) on the circumferential side are inserted into the axial grooves in a radially form-locking manner.

Description

Technical Field

[0001] The invention relates to a stator for an electric motor, in particular for an electric steering motor of a motor vehicle, having stator teeth arranged in a star shape and a stator base body with a stator yoke. The invention also relates to an electric motor having such a stator, which is arranged in a motor housing. Background Art

[0002] An electric motor, as an energy converter for converting electrical energy into mechanical energy, comprises a stator forming the stationary motor part and a rotor forming the moving motor part. In inner rotor motors, the stator is usually provided with a stator yoke, on which stator teeth are arranged radially toward the center, that is, inwardly extending in a star shape, and whose free ends facing the rotor form so-called pole shoes. Windings or coils are applied to the stator teeth, which are interconnected to form stator windings and generate a magnetic field during electric motor operation. In order to guide and intensify the magnetic field generated by the energized windings, the stator material is usually metallic, for example made of soft magnets.

[0003] DE 10 2013 009 407 A1 discloses a stator for an electric motor, which is formed by a star-shaped stack of stator sheets and a cylindrical stator yoke formed by stacked annular sheets, wherein the star-shaped stack of stator sheets is inserted into the stator yoke, wherein a plurality of annular sheets each have at least one bent tab on the outer circumference. By means of the radially extending bent tabs, it is possible to fix the stator in a housing and simultaneously perform centering and positioning. Here, in the engaged state, the stator only abuts against the inner wall of the housing using a contact point formed by the bent tabs arranged at an exposed position. If each annular sheet is provided with a notch into which the bent tab can be bent before or during the stator and housing engagement process, a space-saving structure of an electric motor with a stator inserted into its housing can also be achieved.

[0004] It is known from JP 2014-018001 A1 to fix the stator of an electric motor in a predetermined position within a motor housing by means of a spring tab, wherein the fixing tab is held on the housing with one end and the other end of the fixing tab is inserted into an axial engagement groove on the outer circumference of the stator, extending obliquely into the housing interior.

[0005] DE 10 2007 058 072 A1 discloses an electric motor having a stator which is constructed from a laminated core and is arranged in a housing, wherein the laminated cores are held together by means of spring clips which axially overlap the laminated core and support the laminated core radially against the inner wall of the housing. The spring clips have spring backs which radially extend beyond the outer circumference of the laminated core and have clamping feet on opposite narrow sides which overlap the laminated core at the end.

[0006] In particular, in electric steering motors for motor vehicles, the stator can deform due to electromagnetic forces caused by operation, wherein such deformations can be so great, for example in a 10-pole electric motor, that high structure-borne noise is transmitted to the motor housing that accommodates the stator. In order to reduce the transmission of structure-borne noise, the stator should be decoupled from the housing. Summary of the invention

[0007] The object of the invention is to specify a particularly suitable stator for an electric motor. In particular, the stator should be particularly suitable for reducing or avoiding the transmission of structure-borne noise to the motor housing in terms of decoupling. The stator should be insertable or installable in the housing and decoupled from the housing.

[0008] Furthermore, an electric motor is to be specified which has such a stator in a housing (motor housing).

[0009] According to the invention, this object is achieved with respect to the stator by means of the features of the invention and with respect to the electric motor by means of the features of the invention.

[0010] For this purpose, a stator for an electric motor has a stator base body with a stator yoke as a magnetic return and a plurality of stator teeth, which extend radially inwards in the direction of a central stator axis or motor axis and end in so-called pole shoes. The stator base body can be designed as a solid body in a so-called single-tooth design or star yoke design, wherein the stator teeth are inserted into a cylindrical stator yoke, for example, as a star rim.

[0011] A certain number of axial grooves are provided on the outer circumference of the stator base body, into which engaging elements are inserted radially in a form-fitting manner, the engaging elements projecting radially beyond the stator base body on the circumferential side.

[0012] The coupling element preferably has a platelet-shaped or strip-shaped base body and at least one radially protruding coupling element that protrudes from the axial groove in the radial direction. The coupling element inserted into the axial groove preferably forms a (mechanical) interface with the motor housing in which the stator is inserted. This interface has, in particular, a decoupling, damping, clamping, positioning and / or fixing effect (function).

[0013] The coupling element, which preferably acts as a decoupling or damping element, is inserted into the respective axial groove on the yoke side or return side of the stator base body by being pushed in the axial direction and engages the undercut formed in the axial groove from behind in a suitable manner. For this purpose, the respective axial groove is suitably dovetail-shaped. The axial groove can also be T-shaped. It is important that the axial groove provides a radial undercut, which is engaged from behind by the coupling element or the base of the coupling element. Other shapes (cross-sectional shapes) of the axial groove are also conceivable, such as a partial circular shape or a T-shape having a local protrusion or a local depression (groove) in the groove bottom of the horizontal T-shaped side of the axial groove.

[0014] A "positive fit" or "positive connection" between at least two parts connected to one another is understood here and hereinafter to mean in particular that the parts connected to one another are held together at least in one direction, here in the radial direction with respect to the central axis of the stator and the axis of rotation of the electric motor, by a direct interlocking engagement of the contours of the parts themselves. The "prevention" of mutual movement in this direction, here in the radial direction, is therefore due to the shape. In the present case, the coupling element is therefore held radially in the axial groove of the stator tooth in a positively locking manner.

[0015] The coupling element can be an injection molded part or a stamped and bent part. The base body protrudes on both sides in the circumferential direction beyond the respective coupling element transversely to the axial direction. The base body engages behind the (azimuthally) groove sides of the axial groove extending in the circumferential direction of the stator with the azimuthally protruding sections on the longitudinal sides extending in the axial direction, thereby establishing a radial form fit between the spring element and the respective stator tooth.

[0016] In a suitable development of the engagement element, a shaped block is arranged on the narrow side (end side) of the base body. The shaped block expediently has a contact edge, with which the engagement element rests on the end side of the stator base body, especially in the region of the respective stator tooth.

[0017] In a suitable advantageous design of the coupling element, at least one claw is provided on the longitudinal side of the base body. The respective claw is bent upward from the plane of the base body of the coupling element in a suitable manner. This enables the coupling element to be reliably fixed (held, fastened) in the axial groove of the stator base body associated with the coupling element.

[0018] The electric motor according to the invention comprises a rotor shaft and a rotor fixed relative to the shaft, as well as a stator and a housing, wherein the stator is arranged in the housing in a manner decoupled, clamped and / or damped, in particular against structure-borne noise, by means of a coupling element which is inserted axially into an axial groove on the outer circumference and is held radially in the axial groove in a form-locking manner. The stator is supported on a bearing shield of the electric motor by means of a shaped block of the coupling element inserted into the axial groove, so that the stator is also decoupled from the bearing shield or is damped relative to the bearing shield. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The embodiments of the present invention are explained in detail below with reference to the accompanying drawings.

[0020] Figure 1 A perspective view of a stator of an electric motor having a first variant of a stator base body and radially inwardly oriented stator teeth and radially positively engaged engagement elements inserted into axial grooves on the circumferential side;

[0021] Figure 2 A perspective view of a stator of an electric motor having a second variant of a stator base body and radially inwardly oriented stator teeth (star yoke design) and radially positively engaged engagement elements inserted into axial grooves on the circumferential side;

[0022] Figure 3 A partially cut-away side view shows the stator base body in the region of a stator tooth, which has an engagement element inserted into an axial groove, whose radially protruding coupling element rests on the inner wall of the housing (motor housing);

[0023] Figure 4 showing the engagement element in perspective;

[0024] Figure 5 A perspective view of a section of a stator base body having engagement elements inserted into axial grooves on its outer circumference;

[0025] Figure 6 Shown in end view Figure 5 A section in which the section has an axial groove that is dovetail-shaped in cross section;

[0026] Figure 7 and Figure 8 A stator base body is shown in a fragmentary end-on view in the yoke region with a T-shaped axial slot in cross section, the axial slot having a rounded or angled side contour;

[0027] Fig. 9 Based on Figure 7 and 8 The view of FIG. 1 shows a generally T-shaped axial groove having a local depression on the horizontal T-shaped side;

[0028] Fig.10 Based on Figure 7 and Figure 8 The view of FIG. 1 shows a partially circular axial groove; and

[0029] Fig.11 and Fig.12 Based on Figure 7 and 8 The view of FIG. 4 shows an approximately T-shaped axial groove having a local projection on the horizontal T-side.

[0030] Parts that correspond to one another are provided with the same reference symbols in all the figures. DETAILED DESCRIPTION

[0031] Figure 1 and Figure 2 A stator 1 is shown, whose stator base body 2 has a number (in the exemplary embodiment twelve) of stator teeth 3, which extend (radially) inwardly in the direction of the central rotation axis D shown in the figure in the radial direction R. Free spaces 4 are formed between the stator teeth 3, in which windings of coils are accommodated in a manner not shown in detail, which are connected to one another in a star or delta connection to form a stator winding or rotating field winding.

[0032] Look again Figure 5 and Figure 6 The stator base body 2 has, in the region of each stator tooth 3, a plurality of stator teeth 3 extending in the circumferential direction U ( Figure 1 ) an azimuthal yoke section or return section 3a and a radial side edge 3b extending in the circumferential direction U and an azimuthal pole shoe section 3c extending again in the circumferential direction U.

[0033] The yoke section or return section 3a forms a yoke J of the stator 1 or of the stator base body 2, according to Figure 2 In the variant of the so-called star-shaped yoke design, the yoke is a separate part, while the radial sides 3b of the stator teeth 3 and the pole shoe sections 3c form the so-called star body S of the stator 1 or of the stator base body 2, which is inserted into the yoke J. In the single-tooth design (not shown), the stator 1 or its stator base body 2 consists of a single stator tooth 3, while in the single-tooth design according to Figure 1 In a variant of the present invention, the stator 1 or its stator base body 2 is designed as a solid body or as a sheet metal stack consisting of individual sheets.

[0034] On the outer periphery 5 of the yoke J, that is to say on the outer peripheral side of the respective yoke or return section 3a of the corresponding stator tooth 3, in the axial direction A ( Figure 1 ) and radially inwardly extending toward the axis of rotation D are introduced into the stator base body 2. In a preferred embodiment, the respective axial groove 6 is dovetail-shaped, as in Figure 6 It can be seen more clearly in .

[0035] When the stator 1 is wound, the radial sides 3 b of the stator teeth 3 carry single, double or multiple coils of the stator or rotating field winding. The joining elements 7 are inserted radially into the respective axial grooves 6 of the corresponding stator teeth 3 in a form-fitting manner.

[0036] Look again Figure 4 The coupling element 7 has a base 7a and a plurality of (two in the embodiment) coupling elements 7b. The base 7a protrudes from the respective coupling elements 7b on both sides in the axial and radial directions A or R and then in the circumferential direction U, such as in Figure 5 It can be seen clearly in the figure. Figure 4 ), so that the engagement element 7 is embedded in the axial groove 6 from behind based on the groove flank 6a formed in a dovetail shape of the axial groove 6. The groove flank 6a is formed with an undercut for the engagement element 7 pushed into the axial groove 6 axially.

[0037] On the outside of the base 7b of the coupling element 7, in the embodiment on both sides, the protruding portion 8 is formed with three claws or teeth 9. These claws 9 are bent from the plane of the base 7b in the direction of the upright coupling element 7b. At one of the narrow sides 10 of the coupling element 7, the coupling element has a shaped block 7c. The shaped block has or is formed with a contact edge or a contact surface 11, which extends from the plane of the base 7a in the radial direction R on the side facing away from the coupling element 7b. With the contact edge or the contact surface 11, the coupling element 7 is placed in the respective axial groove 6 in the assembled state and abuts against the end side 12 of the respective yoke section or return section 3a.

[0038] Figures 7 to 12 Variations of the geometry or shape (cross-sectional shape) of the azimuth slots 6 in the respective yoke section or return section 3a of the stator base body 2 are shown. Figure 7 and Figure 8 A T-shaped axial groove 6 is shown, wherein Figure 7 In the embodiment, the horizontal T-shaped side 6b is rounded at least approximately circularly in the region of the groove flank (joining edge or undercut edge) 6a where the undercut is formed. Figure 8 In an embodiment, the area is slightly rounded or angled.

[0039] In accordance with Fig. 9 In the embodiment of FIG. 1 , the axial groove 6 has a radial depression or groove 13 in its groove bottom 6 c.

[0040] In accordance with Fig.10 In the embodiment of the present invention, the axial groove 6 is partially circular with a partial circle of preferably (250±20)°, so that a sufficiently effective undercut is formed by the groove flank 6a.

[0041] according to Fig.11 and Fig.12 The embodiments of the present invention again respectively show a substantially T-shaped axial groove 6. Here, the axial groove 6 has a wedge-shaped or conical ( Fig.11 ) and a truncated cone-shaped local protrusion 14 or 15.

[0042] Figure 3 The partially cut-away illustration shows an electric motor 16 having a stator 1 without a stator or rotating field winding, which is inserted into a housing (motor housing) 17. Also indicated is a rotor 18, which carries permanent magnets and is arranged within the stator 1 so as to be rotatable about an axis of rotation D with the formation of a gap. Also indicated is a rotor shaft or motor shaft 19, on which the rotor 18 is mounted in a shaft-fixed manner.

[0043] Within the housing 17, the stator 1 abuts against the inner wall 20 of the motor housing 17 via the coupling elements 7b of the coupling elements 7, which are arranged radially and thus extend beyond the outer circumference 5 in the radial direction R. In this way, the stator 1 is decoupled from the housing (motor housing) 17 of, for example, a 10-pole electric motor 16. In addition, the stator 1 abuts against the bearing shield 21 at the end side via the shaped blocks 7c of the coupling elements 7 and is thus also decoupled from the bearing shield. The transmission of structure-borne noise, for example due to electromagnetic forces generated during operation, to the housing 17 and the bearing shield 21 is thereby reduced in that the stator 1 is decoupled from the housing 17 and, if necessary, from the bearing shield 21 by means of the coupling elements 7. The coupling elements 7 can additionally or alternatively also fulfill the tasks of damping, fixing and / or positioning.

[0044] The coupling element 7 can be inserted automatically and in a particularly simple manner into the axial groove 6 in the axial direction A. In addition, the coupling element 7 is held radially positively and thus securely within the axial groove 6. The coupling element 7 is further fixed in the axial groove 6 by means of claws 9 which are arranged azimuthally and are bent slightly radially upward.

[0045] The present invention is not limited to the above-described embodiments. On the contrary, other key points of the present invention can also be derived therefrom by those skilled in the art without departing from the subject matter of the present invention. In particular, in addition, the individual features described in conjunction with the embodiments can also be combined with each other in other ways without departing from the subject matter.

[0046] Furthermore, the described solution can be used not only for the specifically shown uses, but also for similar implementations in other motor vehicle applications, such as electric brake motors, door and tailgate systems, window lifts, vehicle locks, adjustable seat and interior space systems, as well as electric drives, controls, sensors and their installations or other electric machines and systems in vehicles.

[0047] Reference numerals list

[0048] 1 Stator

[0049] 2 Stator base

[0050] 3 Stator teeth

[0051] 3a Yoke section / return section

[0052] 3b Radial side

[0053] 3c Pole shoe section

[0054] 4 Free Space

[0055] 5 periphery

[0056] 6 Axial groove

[0057] 6a Groove flank / undercut

[0058] 6b T-Shaped Side

[0059] 6c Groove bottom

[0060] 7 Joining elements

[0061] 7a Matrix

[0062] 7b Coupling element

[0063] 7c Forming block

[0064] 8 Excess

[0065] 9 Claws / teeth

[0066] 10 Narrow side

[0067] 11 Abutment edge / abutment surface

[0068] 12 End side

[0069] 13 Depression / groove

[0070] 14 Wedge-shaped / conical protrusions

[0071] 15. Truncated cone-shaped protrusion

[0072] 16 Electric Motor

[0073] 17 Motor housing / housing

[0074] 18 Rotor

[0075] 19 Rotor shaft / motor shaft

[0076] 20 Inner wall

[0077] 21 Bearing cover

[0078] A Axial direction

[0079] D Rotation axis

[0080] J Yoke

[0081] S Star

[0082] R Radial direction

[0083] U Circumferential direction

Claims

1. A stator (1) for an electric motor (16), comprising stator teeth (3) arranged in a star shape and a stator base body (2) with a stator yoke, a number of axial grooves (6) being arranged on the outer circumference (5) of the stator base body, and engaging elements (7) which radially protrude from the stator base body (2) on the circumferential side and are inserted into the axial grooves in a radially positively locking manner, The respective engagement element (7) has a base body (7a) and at least one coupling element (7b) which protrudes in the radial direction (R) and projects from the axial groove (6), The base body (7a) protrudes from the respective coupling element (7b) in the circumferential direction (U) and in the axial direction (A) of the axial groove (6), At least one claw (9) is arranged on a longitudinal side of the base body (7a).

2. The stator (1) according to claim 1, It is characterized in that The respective axial groove (6) is dovetail-shaped or T-shaped.

3. The stator (1) according to claim 1 or 2, It is characterized in that A protrusion (14, 15) or a groove-shaped depression (13) is provided in the groove bottom (6c) of the axial groove (6).

4. The stator (1) according to claim 1, It is characterized in that A shaped block (7d) is arranged on the narrow side (10) of the base body (7a), the shaped block protruding axially from the axial groove (6).

5. The stator (1) according to claim 4, It is characterized in that The shaped block (7d) has a contact edge or a contact surface (11), by means of which the engagement element (7) rests against an end side (12) of the stator base body (2).

6. The stator (1) according to claim 1, It is characterized in that The respective claw (9) is bent upward from the plane of the base body (7a).

7. The stator (1) according to claim 1 or 2, It is characterized in that A local protrusion is arranged in the groove bottom (6c) of the axial groove (6).

8. An electric motor (16) comprising a rotor shaft (19) and a rotor (18) fixed relative to the shaft, as well as a stator (1) and a housing (17) according to any one of claims 1 to 7, wherein the stator (1) is arranged in the housing with a coupling element (7) inserted into an axial groove (6) on the outer circumference and held in the axial groove in a radially positive locking manner.

9. The electric motor (16) according to claim 8, It is characterized in that The engagement element is an engagement element which is inserted axially into an axial groove (6) on the outer circumference and is held radially in the axial groove in a form-fitting manner.

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