Electric motor

Abstract

The invention relates to an electric motor (2), in particular a steering motor for a motor vehicle, comprising a stator (6) with a cylindrical stator base body (18) with radially inwardly directed stator teeth (20) and with a number of first axial grooves (30) introduced into the stator base body (18) on the circumference, a motor housing (4) for receiving the stator (6), wherein a number of second axial grooves (50) are introduced into a housing inner wall (58), which are arranged in alignment with the first axial grooves (30), at least one spring element (34) which has a spring base body (36) which is or can be inserted in a radially form-fitting manner into one of the first axial grooves (18), and at least one spring arm (38) which is flared or bent out from the spring base body (36) and projects radially beyond the stator base body (18) on the circumference, wherein the spring arm (38) has a stiffening contour (62) along an arm longitudinal direction (AL),which increases a tangential stiffness of the spring arm (38), and wherein the spring arm (38) engages at least partially radially and tangentially in a form-fitting manner in one of the second axial grooves (50) on the free end side.

Description

[0001] The invention relates to an electric motor, in particular a steering motor for a motor vehicle, comprising a cylindrical stator base body with radially inwardly directed stator teeth and a number of axial grooves on the circumference, as well as spring elements inserted or insertable therein. The invention further relates to a spring element for such an electric motor.

[0002] In modern motor vehicles, electric motors are used in a variety of ways to drive various actuators. For example, electric motors are used as window regulators, sunroofs, or seat adjustment drives, as steering drives (EPS, Electrical Power Steering), as radiator fan drives, or as transmission actuators. Such electric motors must have a relatively high torque or power density and be reliable even at high temperatures.

[0003] An internal rotor electric motor typically comprises a stator, which forms the stationary motor part, and a rotor, which forms the moving motor part. In an internal rotor motor, the stator is usually provided with a stator yoke on which stator teeth are arranged, projecting radially towards the center or inward in a star shape. The free ends of these teeth, facing the rotor surrounded by the stator, form the so-called pole piece. Windings or coils are applied to the stator teeth. These windings are connected to the stator winding and generate a magnetic field during electromotive operation. To guide and amplify the magnetic field generated by the energized windings, the stator material is usually metallic, for example made of soft magnetic iron.

[0004] The stator must be mounted securely in the motor housing for low-noise operation. Both radial and anti-rotation locking of the stator are desirable, preventing tangential rotation. Therefore, the stator is typically mounted in the electric motor housing using additional damping or decoupling elements, which not only secure the position but also reduce structure-borne noise during operation.

[0005] Spring elements in the form of decoupling springs are conceivable as damping or decoupling elements. Spring elements of this type are known, for example, from DE 10 2020 206 949 A1 and DE 10 2022 201 621 A1. The spring elements are inserted into axial grooves of the stator and are supported or damped toward the motor housing by radial spring arms. For tangential support and / or damping, the spring arms engage, for example, at the free end, in axial grooves in the inner housing wall, so that any tangential forces that occur are dampened by the tangential restoring force of the spring arms.

[0006] However, under increased loads, such as a mechanical shock, it can happen that the spring arms slide at least partially out of the axial grooves of the inner wall of the housing, so that tangential forces cannot be reliably supported or dampened.

[0007] In this context, a "mechanical shock" is understood to mean a sudden and extreme mechanical load acting on the electric motor. In particular, this is a load greater than 50 g, for example, between 50 g and 100 g, where g is the standard acceleration due to gravity (approximately 9.81 m / s). 2 ) corresponds to.

[0008] The invention is based on the object of providing a particularly suitable electric motor. In particular, reliable damping and / or decoupling of the stator with respect to a motor housing is to be ensured, even in the event of a mechanical shock. The invention is further based on the object of providing a particularly suitable spring element for such an electric motor.

[0009] With regard to the electric motor, the problem is solved according to the invention with the features of claim 1, and with regard to the spring element with the features of claim 8. Advantageous embodiments and further developments are the subject of the dependent claims. The advantages and embodiments cited with regard to the electric motor are also transferable to the spring element, and vice versa.

[0010] The electric motor according to the invention is designed, for example, as a synchronous motor, in particular as a steering motor for a motor vehicle. The electric or steering motor is, in particular, part of a steering drive (Electrical Power Steering, EPS).

[0011] The brushless electric motor comprises a stator with a cylindrical stator base body with radially inwardly directed stator teeth and with a number of first axial grooves formed circumferentially in the stator base body. A "first axial groove" is understood here and below to mean, in particular, a radially inwardly directed groove or groove-like recess on the outer circumference of the stator base body, with the longitudinal direction of the groove extending along the axial direction and the width of the groove extending along the tangential direction of the stator.

[0012] "Axial" or an "axial direction" is understood here and below to mean, in particular, a direction parallel (coaxial) to the axis of rotation of the electric motor, i.e., perpendicular to the end faces of the stator. Accordingly, "radial" or a "radial direction" is understood here and below to mean, in particular, a direction oriented perpendicular (transverse) to the axis of rotation of the electric motor along a radius of the stator or electric motor. "Tangential" or a "tangential direction" is understood here and below to mean, in particular, a direction along the circumference of the stator or electric motor (circumferential direction, azimuthal direction), i.e., a direction perpendicular to the axial direction and the radial direction.

[0013] The stator base body is designed, for example, as a solid body, in the so-called single-tooth design or in the star-yoke design, in which the stator teeth are inserted into a cylindrical stator yoke, for example as a star ring.

[0014] A motor shaft (rotor shaft) with a fixed rotor is preferably rotatably mounted in the stator. The electric motor has a motor housing in which the stator and rotor are housed.

[0015] The motor housing has an inner wall facing the stator base body, into which a number of second axial grooves are formed. A "second axial groove" is understood here and below to mean, in particular, a radially outwardly directed depression, groove, deformation, groove, or groove-like recess on the inner circumference of the motor housing, wherein the longitudinal direction of the groove extends along the axial direction and the width direction extends along the tangential direction of the electric motor or motor housing.

[0016] The number of first and second axial slots is preferably equal, meaning that each first axial slot of the stator is assigned a second axial slot of the motor housing. The first and second axial slots are arranged radially aligned with one another. In other words, the first and second axial slots are arranged opposite one another, with a radial clearance or a radial clear width being provided between the first and second axial slots.

[0017] The electric motor or its stator has at least one spring element. Preferably, the electric motor has a number of spring elements corresponding to the number of first axial grooves.

[0018] The spring elements of the present invention are based on the applicant's earlier German applications DE 10 2020 206 949 A1 and DE 10 2022 201 621 A1. Their disclosure content, in particular their claims (with associated explanations), is hereby expressly incorporated into the present application. The content of these applications is therefore incorporated by reference into the disclosure of the present application.

[0019] Each spring element comprises a plate-shaped spring base body, for example, which is inserted or can be inserted radially into one of the first axial grooves with a positive fit. The or each first axial groove is designed as a radial undercut or as a radial undercut in the outer circumference of the stator base body. This allows for a reliable and operationally safe radially positive holding or fixing of the spring element in the first axial groove in a structurally simple manner.

[0020] The spring element, which preferably acts as a decoupling or damping element and is inserted into the respective first axial groove of the stator base body on the yoke or return side, in particular by being pushed or inserted in the axial direction, engages behind the undercut formed in the first axial groove. For this purpose, the respective first axial groove has a dovetail-shaped or T-shaped cross-section, for example. Other shapes (cross-sectional shapes) of the first axial groove are also conceivable, for example a partial circle shape or a T-shape with a local elevation or a local depression (bead) in the groove base of the horizontal T-leg of the first axial groove.

[0021] For example, a first axial groove is used, as described in the applicant's application WO 2020 / 249555 A1. The disclosure content of this application, in particular its claims (with associated explanations), are hereby expressly incorporated into the present application. Regarding the radial undercut of the first axial groove, special reference is made to claims 2 and 3 with the associated explanations, especially on pages 3 / 4 and 8 / 9, as well as to the Fig. 6 to 12.

[0022] The spring base body has at least one spring arm (spring tab, radial spring) that extends outward or is bent outward from the spring base body, which, when inserted into the corresponding first axial groove, radially projects beyond the circumference of the stator base body. The number of spring arms of the spring element or spring base body is selected, for example, depending on the length of the stator base body (stator length) and preferably increases with increasing stator length.

[0023] According to the invention, the spring arm has a stiffening contour along a (spring) arm longitudinal direction, which increases the tangential stiffness of the spring arm, i.e., the stiffness in the (spring) arm width direction. In particular, the stiffening contour increases the bending resistance of the spring arm to tangential loads or loads directed in the arm width direction.

[0024] When assembled, the spring arm engages at least partially radially and tangentially in one of the second axial grooves at the free end. This creates a particularly suitable electric motor.

[0025] A "positive connection" or a "positive connection" between at least two interconnected parts is understood here and below in particular to mean that the interconnected parts are held together at least in one direction—here, the radial and tangential directions relative to the central axis of the stator and the rotational axis of the electric motor—by a direct interlocking of the contours of the parts themselves. The "blocking" of mutual movement in this direction is therefore due to the shape.

[0026] When assembled, the spring element engages both in the first axial groove of the stator and in the second axial groove of the motor housing. The spring arm, or rather the longitudinal direction of the arm, is arranged at a particularly acute angle to the spring base body, so that the spring arm rests radially resiliently against the motor housing or the bottom of the second axial groove due to the radial form fit. This reliably decouples or dampens radial forces occurring during operation. The material thickness and the angle of inclination of the spring arm to the spring base body, for example, allow the characteristic curve of the spring arm—i.e., the relationship between spring force and spring travel—to be specified or adjusted.

[0027] When assembled, the spring or free end of the spring arm rests positively and / or non-positively against the motor housing or in the second axial groove. The spring arm also acts as primary protection against mechanical twisting of the stator along the tangential direction.

[0028] Due to the tangential positive engagement of the spring arm with the axially oriented side walls of the second axial groove, tangential forces occurring during operation are introduced into the spring arm as shear forces and thus dampened or decoupled. The spring arm has an arm width that essentially corresponds to the width of the second axial groove, ensuring a reliable and, if possible, backlash-free tangential positive engagement. It is recognized that the spring arm width is also crucial for the tangential stiffness or restoring force of the spring arm. The stiffening contour extending along the longitudinal direction of the arm increases the tangential stiffness of the spring arm, which subsequently improves the fixation and contact stiffness of the spring arm in the second axial groove. This advantageously reduces the risk of the spring arm sliding or slipping out of the second axial groove under increased load.This enables reliable decoupling or damping even in the event of a mechanical shock.

[0029] The stiffening contour essentially does not change the radial stiffness or spring constant of the spring arm. In other words, the stiffening contour has only a minor influence on the radial stiffness of the spring arm, as this is essentially determined by the angle of inclination relative to the spring body and the material thickness.

[0030] The improved retention of the spring arm in the second axial groove, achieved by the stiffening contour, is independent of the housing material and / or the machining process of the second axial groove. In other words, the retention of the spring arm is essentially independent of the roughness of the housing inner wall or the second axial groove. As a result, housing tolerances have less influence on the spring element and the resulting decoupling or damping.

[0031] The spring elements isolate the stator from structure-borne noise in the motor housing while simultaneously maintaining sufficient radial and / or tangential stiffness. By specifically adapting and designing the radial and tangential (spring) stiffness of the spring elements used, the requirements for structure-borne noise are met. This noise is generated by the transmission of vibrations generated by the stator as a result of electromagnetic excitation to the motor housing.

[0032] This improves the acoustic properties of the electric motor during operation because the spring elements prevent the oscillations and / or vibrations generated by the stator from being transmitted to the motor housing as structure-borne sound.

[0033] The spring element, enhanced by the stiffening contour, thus ensures consistently reliable and operationally safe radial and tangential spring-loaded (de-)coupling or damping of the stator to the motor housing. In particular, the stator is better secured in the motor housing under shock loads. This makes the electric motor more robust against mechanical loads, especially against mechanical shock. Furthermore, the spring elements also ensure particularly stable anti-twist protection against mechanical twisting of the stator in the motor housing.

[0034] The spring element design according to the invention is also more robust with regard to tolerances, for example, with regard to assembly tolerances when installing the stator in the motor housing. In other words, any tolerances that occur have only a minor or negligible impact on the decoupling and damping achieved by the spring element. This simplifies the assembly of the electric motor.

[0035] In one conceivable embodiment, the spring element has, for example, at least one clamping claw or claw nose on a longitudinal side of the spring base body to improve the tangential and / or axial fastening or fixing in the first axial groove. The respective clamping claw is suitably bent out of the plane of the spring base body of the spring element. This achieves reliable fixing (holding, fastening) of the spring element in the associated first axial groove of the stator base body. This means that the spring element is designed with a claw design in order to claw tangentially and / or axially in the first axial groove. This ensures reliable positive and / or non-positive fixing of the spring element in the tangential direction. The clamping claws or claw noses are preferably arranged in pairs on the opposite longitudinal sides of the spring base body.

[0036] The conjunction “and / or” is to be understood here and in the following in such a way that the features linked by this conjunction can be formed both together and as alternatives to one another.

[0037] A "positive connection" or a "positive connection" between at least two interconnected parts is understood here and below in particular to mean that the interconnected parts are prevented from sliding against each other due to a frictional force acting between them. If a "connecting force" causing this frictional force (this means the force that presses the parts against each other, for example, a screw force or the force of gravity itself) is missing, the positive connection cannot be maintained and can therefore be released.

[0038] In a preferred embodiment, the second axial grooves are introduced into the housing inner wall by a joining process of the stator into the motor housing. In other words, the motor housing or the housing inner wall is manufactured without the second axial grooves, and the axial grooves are introduced into the housing inner wall by the stator when the stator is inserted into the motor housing. In particular, the second axial grooves are introduced by the spring arms of the spring elements that bear radially against the housing inner wall, for example, they are embossed, scratched in, or formed in. This enables particularly simple and expedient production of the second axial grooves. In particular, it is thus always ensured that the second axial grooves are radially aligned and parallel to the first axial grooves, thus ensuring reliable holding and fixing of the stator within the motor housing.It is conceivable that the stiffening contour is designed in such a way that it also supports the reliable introduction of the second axial grooves.

[0039] In an alternative embodiment, it is also conceivable, for example, for the second axial grooves to be machined or tooled into the inner wall of the housing prior to the joining process. The second axial grooves are thus already present as counter-contours before the stator is inserted. Controlled manufacturing makes it possible to reinforce or more precisely define the holding effect of the spring arms, thus achieving more stable mounting and support of the stator within the motor housing.

[0040] In an advantageous embodiment, the stiffening contour is designed such that it converts a tangential support force in the second axial groove, i.e. a tangential force or shear force acting on the spring arm, at least partially into a radial force acting along the radially arranged spring arm.

[0041] By converting the tangential force into a tangential and radial relationship, the stiffening contour creates a self-locking effect that counteracts a loss of contact between the spring arm and the second axial groove. The stiffening contour enables the spring element or spring arm to maintain or lock its position in the second axial groove. The spring arm or stiffening contour is thus designed to automatically lock itself or remain in this position when subjected to tangential stress.

[0042] In a preferred embodiment, the stiffening contour is substantially V- or U-shaped, so that the spring arm has an approximately V- or U-shaped cross-sectional shape in a cross-sectional plane perpendicular to the longitudinal direction of the arm. In other words, the side edges are, for example, bent, arched, angled, or kinked with respect to a center line running parallel to the longitudinal direction of the arm. The stiffening legs (U-legs, V-legs) thus formed in cross-section, i.e., the side edges of the spring arm, form the contact surface in the second axial groove. In other words, the spring arm preferably bears only in the region of the free ends of the stiffening legs.

[0043] This design ensures reliable self-locking and the conversion of a tangential force into a tangentially and radially directed force. When a tangential load is applied, the stiffening legs are at least partially moved toward each other, resulting in radially directed force components along the longitudinal direction of the legs. Accordingly, the spring or restoring force acts in both the tangential and radial directions, thus supporting the self-locking effect.

[0044] By dimensioning the angle of inclination of the stiffening legs relative to the spring base, a radial component of the reaction or restoring force can be adjusted or specified. The greater the angle of inclination, the greater the radial component of the reaction force triggered by a load, for example, a (mechanical) shock. The angle of inclination is, for example, less than 10°, in particular between 8° and 5°, preferably around 6°. The exact value for a suitable angle of inclination depends on many factors (material pairing of spring element and motor housing, surface roughness of the motor housing, surface tension, temperature range during normal operation of the electric motor, edge quality of the stiffening legs, material post-treatment, hardness, etc.) and is selected specifically for the respective application or for the respective electric motor.

[0045] The spring arm rests resiliently against the motor housing or the second axial groove at its free end, particularly in the area of ​​the free ends of the stiffening legs. In a practical development, the free end of the spring arm is convexly curved with respect to the second axial groove. The convexly shaped bend creates a rounded contact surface for the spring arm at or in the second axial groove, enabling easy axial insertion or insertion of the spring arm free end into the second axial groove.

[0046] In one conceivable embodiment, the stiffening contour extends beyond the bend. Due to the bend and the stiffening shape, the free end of the spring arm preferably has a roughly saddle-shaped or anticlastic curved geometry. This further stabilizes the free end, particularly the contact surfaces formed by the free ends of the stiffening legs, against tangential loads. This ensures particularly stable engagement or contact with the second axial groove.

[0047] In one possible embodiment, the respective spring element is designed as a single-piece, i.e., a one-piece or monolithic, stamped and bent part. "Single-piece" specifically means that at least one spring arm is formed integrally with the spring base body. This results in a particularly cost-effective and component-reduced design of the spring element, which has a beneficial impact on the manufacturing costs of the electric motor.

[0048] In an advantageous further development, the stiffening contour is designed as an embossed portion of the spring arm. In other words, the stiffening contour is embossed into the spring arm. The stiffening contour is designed, for example, as a bead-shaped recess in the spring arm.

[0049] The spring element preferably has a coupling spring on a narrow side or end face of the spring base body, which projects axially out of the first axial groove. The first axial groove extends essentially over the entire axial length of the stator, such that the coupling spring projects axially upwards on a stator end face and is resiliently supported axially on a housing cover of the motor housing at the free end. Due to the coupling spring, the spring element is thus also provided for axially supporting and fixing the stator in a motor housing, and is suitable and configured for this purpose. A particularly expedient embodiment is one in which the coupling spring connects to the spring base body via a radially raised, in particular approximately S-shaped, bent section, forming a contact edge.With this contact edge, the spring element rests against one end face of the stator base body, preferably in the manner of a line contact.

[0050] The spring element according to the invention is intended for an electric motor as described above and is suitable and configured therefor. The spring element is designed in particular as a decoupling and damping element for mounting the stator in the motor housing and, in the assembled state, also provides tangential anti-twist protection for the stator within the motor housing. For this purpose, the spring element has a spring base body, for example a plate-shaped one, from which at least one spring arm is extended or bent out. The spring arm is arranged at an angle of inclination to the spring base body such that, in the assembled state, the spring arm projects radially beyond the stator on the circumference. According to the invention, the spring arm has a stiffening contour along a longitudinal arm direction, which increases a tangential stiffness of the spring arm, i.e. a stiffness in the transverse arm direction.This results in a particularly suitable spring element for an electric motor, in particular for a steering motor.

[0051] An embodiment of the invention is explained in more detail below with reference to a drawing. In the drawings: Fig. 1 in perspective view an electric motor with a motor housing and with a bearing plate, Fig. 2 shows a perspective view of a stator and a rotor of the electric motor, Fig. 3 shows a section of the electric motor, Fig. 4 in perspective view the spring element, Fig. 5 in side view the spring element, Fig. 6 in plan view the spring element, Fig. 7 in front view the spring element with a view to a rear side, and Fig. 8a, Fig. 8b shows a schematic sectional view of the motor housing and the spring element under tangential loading.

[0052] Corresponding parts and sizes are always provided with the same reference symbols in all figures.

[0053] The Fig. 1 has a motor housing 4 with a stator 6 and rotor 8 arranged therein ( Fig. 2) appears.

[0054] The electric motor 2, designed, for example, as a permanent magnet synchronous motor, is constructed in this embodiment as an internal rotor. The rotor 8 is fixedly connected to a motor shaft 10. The motor shaft 10 is rotatably mounted in the motor housing 4 by means of two bearings 12. The bearings 12 are designed, for example, as ball bearings. One of the bearings 12 is arranged in a bearing seat 13 of a housing base 14 of the motor housing 4, designed as a (housing) intermediate wall ( Fig. 3). The other bearing 12 is arranged in a bearing plate 16, which, as a housing cover, is mounted axially on the pot-shaped motor housing 4, opposite the housing base 14.

[0055] The Fig. 2 and Fig. The stator 6 shown in more detail in Figure 3 has a stator base body 18. In the illustrated embodiment, the stator base body 18 is designed with twelve stator teeth 20, which extend in a radial direction R (radially) inwardly in the direction of the central axis of rotation D of the electric motor 2 shown in the drawing.

[0056] The stator base body 18 has a stator yoke 21 or yoke, which encloses the stator teeth 20 on the circumference. In the exemplary embodiment shown, the stator base body 18 is designed in a so-called single-tooth design, in which the stator 6 or its stator base body 18 is composed of individual stator teeth 20. In an alternative exemplary embodiment not shown, the stator base body 18 is designed in a star-yoke design, in which the stator yoke 21 is a separate component, and the stator teeth 20 form a so-called stator star, which is inserted into the stator yoke 21. The stator 6 or the stator base body 18 or the stator teeth 20 are designed, for example, as solid bodies or as punched laminated cores made up of individual sheets.

[0057] Between the stator teeth 20, unspecified free spaces are formed in which the windings of (stator) coils 22 are accommodated, which are connected to one another by means of a front-side connection ring (contact unit) 24, for example in a star or delta connection, forming a stator or rotating field winding.

[0058] The coils 22 are arranged on insulating coil bodies 26, which are placed on the stator teeth 20 ( Fig. 3). The coils 22 and coil formers 26 are provided with reference numerals in the figures merely for illustrative purposes. The interconnection ring 24 is placed on the end face of the stator base body 18 and is secured in the (first) axial grooves 30 by means of locking tabs 28. The locking tabs 28 act as positioning or centering lugs.

[0059] The axial grooves 30 are formed in an outer circumference 32 of the stator base body 18, i.e., on the outer circumference side, as grooves or recesses extending in the axial direction A and radially inward toward the rotational axis D. The respective axial groove 30 is designed in particular as a dovetail-shaped or T-shaped radial undercut of the outer circumference 32.

[0060] A spring element 34 is inserted radially and tangentially in each of the axial grooves 30 in a form-fitting manner. The axial grooves 30 and spring elements 34 are provided with reference numerals in the figures merely as examples.

[0061] The Fig. The spring element 34 shown individually in Figures 4 to 7 has a plate-shaped spring base body 36, to which three spring arms 38 as radial and tangential springs, a coupling spring 40 as axial spring, and three pairs of clamping claws 42 are integrally formed, i.e. one-piece or monolithic.

[0062] The spring element 34 is designed in particular as a stamped and bent part, wherein the spring arms 38, coupling spring 40 and clamping claws 42 are flared or bent out of the spring base body 36.

[0063] The coupling spring 40, which is axially directed in the assembled state, is designed in particular as a spring-elastic (spring) tab that is approximately C- or U-shaped. The coupling spring 40 is arranged on a narrow side or end face of the essentially rectangular spring base body 36.

[0064] The spring-elastic spring arms 38 are formed as punched tabs from the spring base body 36 and are bent out of the plane of the spring base body 36 in an approximately C- or U-shape. For this purpose, two of the spring arms 38 are inserted into the spring base body 30, so that two window-like punched openings or recesses 44 are formed in the spring base body 36. The third spring arm 38 is formed on a narrow side or end face of the spring base body 36 opposite the coupling spring 40 and is bent over the spring base body 36.

[0065] The spring element 34 has a spring longitudinal direction and a spring transverse direction not designated in more detail, wherein the spring longitudinal direction in the assembled state is oriented parallel to the axial direction A, and the spring transverse direction is oriented substantially parallel to a tangential direction T. The spring base body 36 is arranged in the plane spanned by the spring longitudinal direction and the spring transverse direction.

[0066] The spring arms 38 are bent upwards at an angle of inclination α relative to the spring base body 36. The angle of inclination α is an acute angle, for example, approximately 40°, in particular 40° ± 5°. The spring arms 38 each extend along an arm longitudinal direction AL and an arm width direction (arm transverse direction) AB. The arm width direction AB runs parallel to the spring transverse direction or tangential direction T. The arm longitudinal directions AL of the spring arms 38 are arranged parallel to one another, at least in the relaxed spring state.

[0067] The arm longitudinal direction AL is arranged accordingly inclined or tilted by the inclination angle α to the spring longitudinal direction or axial direction A, so that the arm longitudinal direction AL, with respect to the assembled state, also has a component along the radial direction R. As a result, the spring arms 38 also act as radial springs.

[0068] The spring base body 36 projects beyond the spring arms 38 in the spring transverse direction or tangential direction T and at least for the two punched spring arms 38 inside the spring base body 36 also in the spring longitudinal direction or axial direction A. The spring base body 36 thus projects beyond the spring arms 38 on both sides in the circumferential or tangential direction T, as shown in Fig. 6 is comparatively clearly visible. The projection on both sides (connecting web, attachment web) 46 engages behind the groove flanks formed within the axial groove 30 in the assembled state, so that the spring element 34 is positively fixed in the axial groove 30 in both the radial and tangential directions. In other words, the groove flanks form an undercut for the spring element 34 axially inserted into the axial groove 30.

[0069] On the spring base body 36 of the spring element 34, three clamping claws or clamping teeth 42 are formed as approximately triangular locking lugs on each of the two long sides, outside the projections 46. The clamping claws 42 are bent upwards from the plane of the spring base body 36 toward the upright spring arms 38. In the assembled state, the clamping claws 42 engage the groove flanks of the axial groove 30 in a force-locking manner, thus securely fixing the spring base body 36 or the spring element 34 to the stator 6.

[0070] The spring arms 38 or the angles of inclination α are oriented in the assembled state in the direction of the bearing plate 16 and protrude from the axial groove 30 radially in the direction of the motor housing 4. The spring element 34 thus has a side view ( Fig. 3, Fig. 5) has a roughly fir-tree or sawtooth-shaped geometry. For assembly, the stator 6 is inserted axially into the motor housing 4, with the spring arms 38 engaging with their respective free ends 48 in a (second) axial groove 50 of the motor housing 4. During insertion, the free ends 48 slide along the axial grooves 50 and are thereby radially compressed or tensioned in the direction of the rotational axis D or in the direction of the spring base body 36. The erected spring arms 38 thus also act as an insertion aid for positioning the stator 6 in the motor housing 4.

[0071] Between the narrow side of the spring base body 34 and the coupling spring 40, an approximately U-shaped bending point 52 is provided, which is bent from the plane of the spring base body 34, first in the direction of the spring arms 38 and then in the opposite direction, wherein a vertical U-leg 54 of the bending point 52 merges or opens into the approximately U-shaped bend of the coupling spring 40. The U-leg 54 forms a contact edge or contact surface, which extends essentially from the plane of the spring base body 36 on the side of the spring base body 36 opposite the spring arms 38 in the radial direction R. With this contact edge or contact surface of the U-leg 54, the spring element 34 lies - as for example in Fig. 3 - in the assembled state inserted into the respective axial groove 30 on an end face 56 of the stator base body 18 or its stator yoke 21 facing the bearing plate 16.

[0072] In the assembled state, the coupling spring 40 extends axially beyond the axial groove 30 and the end face 56 of the stator base body 18. The coupling spring 40 is arranged in particular on the end face 56 of the stator base body 18 opposite the interconnection ring 24.

[0073] As particularly in the Fig. As can be seen in Figure 3, the stator 6 rests in the axial grooves 50 of the motor housing 4 via the radially projecting spring arms 38 of the spring elements 34, which extend beyond the stator 6 on the outer circumference 32 in the radial direction R. In particular, the spring arms 38 rest in the axial grooves 50 in the region of their free ends 48 in a resilient or articulated manner. In this way, the stator 6 is decoupled from the motor housing 4 of the, for example, 10-pole electric motor 2.

[0074] The stator 6 continues to rest on the end face of the bearing plate 16 via the coupling springs 40 of the spring elements 34 and is thus also decoupled or damped relative to it ( Fig. 3). The coupling springs 40 are supported by the U-shaped legs 54 on the end face 56 and are compressed or bent at the free end against an edge of a spring installation space 60 to form the bearing plate 16. In this way, the stator 6 is decoupled from the motor housing 4 or the bearing plate 16.

[0075] The free ends 48 of the spring arms 38 and the free end of the coupling spring 40 are bent or curved towards the plane of the spring base body, so that a rounded, convex contact surface is formed in each case with respect to the axial groove 50 or the bearing plate 16.

[0076] The axial grooves 50 are designed as radially outwardly directed grooves or groove-like recesses on an inner circumference of an inner housing wall 58 of the motor housing 4, wherein the groove longitudinal direction extends along the axial direction A and the groove width direction extends along the tangential direction T of the electric motor 2 or motor housing 4.

[0077] The axial grooves 50 have a groove width which essentially corresponds to the arm width of the spring arms 38 or the free ends 48, so that the free ends 48 are radially positively enclosed on a tangentially oriented groove bottom and tangentially positively enclosed between the approximately radially directed groove side walls or groove flanks.

[0078] Preferably, the free ends 48 introduce the axial grooves 50 into the housing inner wall 58 when inserting or joining the stator 6 to the motor housing 4. In other words, the free ends 48 scratch, emboss, or form the axial grooves 50 into the housing inner wall 58 as they slide along the housing inner wall 58, so that the free ends 48 automatically engage and are guided in the axial grooves 50. Alternatively, the axial grooves 50 are machined, for example, as groove-like millings, before inserting the stator 6 into the housing inner wall 58.

[0079] The spring arms 38 each have a stiffening contour 62 extending along the respective arm longitudinal direction AL. The stiffening contour 62 is arranged centrally or centrally with respect to the arm width. In other words, the stiffening contour 62 runs along an axis of symmetry of the spring arm 38. The stiffening contour 62 also supports, for example, the introduction of the axial grooves 50 into the housing inner wall 58 when the stator 6 is joined to the motor housing 4.

[0080] The stiffening contour 62 is introduced into the respective spring arm 38 as a bead-like embossing. The stiffening contour 62 extends over the curved free end 48, so that the free end 48 has an approximately saddle-shaped or anticlastic curved geometry.

[0081] As for example in the frontal view of the Fig. 7, the spring arm 38 has an approximately U-shaped or V-shaped cross-sectional shape in a sectional plane oriented perpendicular to the arm longitudinal direction AL due to the stiffening contour 62. In other words, the stiffening contour 62 is U-shaped or V-shaped. The resulting bent or raised side edges of the spring arm 38 thus form stiffening legs (U-legs, V-legs) 64 of the stiffening contour 62. The stiffening legs 64 form, at least in sections, the contact surfaces or the mechanical contact points to the axial groove 50 or its groove side walls ( Fig. 8a, Fig. 8b).

[0082] In the illustrated embodiment, the stiffening legs 64 are bent in a V-shape, in particular. For example, the stiffening legs 64 have an angle of inclination β with respect to the spring base body 36 in the arm width direction AB of less than 10° and, for example, more than 6°. In the illustrated embodiment, the angle of inclination β is dimensioned, for example, to approximately 8°, in particular to 8° ± 4°. An opening angle γ between the stiffening legs 64 thus has an obtuse angle, which in the illustrated embodiment is approximately 164°. The angle of inclination β essentially determines a friction angle with the housing inner wall 58 or the axial groove 50.

[0083] The stiffening contour 62 increases the stiffness or the bending resistance of the spring arm 38 against tangential loads or loads directed in the arm width direction AB.

[0084] During operation of the electric motor, the electromagnetic forces that occur cause structure-borne noise from the stator 6. This structure-borne noise is dampened by the spring elements 34 so that it is transmitted to the motor housing 4 to a minimum or not at all. The spring elements 34 thus decouple the structure-borne noise from the stator 6 from the motor housing 4. As shown in the Fig. 4 schematically represented by double arrows, the coupling spring 40 realizes axial suspension (damping, decoupling) 66, and the spring arms 38 each realize a radial suspension 68 and a tangential suspension 70. The radial suspension 68 is realized in particular by changing the spring arm position 38, i.e. by changing the angle of inclination α.

[0085] The stiffening contour 62 increases the spring stiffness of the tangential spring 70, which ensures that the spring arm 38 sits more securely in the axial groove 50. The stiffening provided by the stiffening contour 62 is dimensioned such that the spring arm 38 does not slide or jump out of the axial groove 50, even in the event of a mechanical shock. Thus, the spring arms 38 also ensure a particularly reliable anti-rotation lock of the stator 6 in the motor housing 4.

[0086] The stiffening contour 62 realizes in particular a self-locking and conversion of a tangential force 72 into a tangentially and radially directed force 74. As shown in the schematic and simplified representations of the Fig. 8a and Fig.As shown in Figure 8b, when a tangential force (tangential support force) 72 acts as a shear or transverse force on the spring leg 38, the stiffening legs 64 are at least partially moved toward each other, resulting in radially directed force components along the stiffening legs 64. Accordingly, the spring or restoring force acts in both the tangential and radial directions.

[0087] The invention is not limited to the exemplary embodiment described above. Rather, other aspects of the invention can also be derived from it by those skilled in the art without departing from the subject matter of the invention. In particular, individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the subject matter.

[0088] The electric motor 2 shown in the exemplary embodiment is, in particular, a steering motor of a motor vehicle. The solution described above can be used not only in the specific application described, but also in a similar embodiment in other motor vehicle applications, such as electric brake motors, door and tailgate systems, window lifts, as well as in electric drives and their arrangement in the vehicle, or in other electrical machines and systems. List of reference symbols 2 electric motor 4 engine housing 6 Stator 8 Rotor 10 Motor shaft 12 camps 13 Bearing seat 14 Case back 16 Bearing shield 18 Stator base body 20 stator teeth 21 Stator yoke 22 Stator coil 24 interconnection ring 26 coil bodies 28 locking tongue 30 axial groove 32 outer circumference 34 spring element 36 spring base bodies 38 spring arm 40 coupling spring 42 clamping claw 44 recess 46 overhang 48 freelancers 50 axial groove 52 bending point 54 U-legs 56 front side 58 Housing inner wall 60 spring installation space 62 Stiffening contour 64 stiffening legs 66 Spring action 68 Spring action 70 spring action 72 Tangential force 74 power A axial direction R Radial direction T Tangential direction D axis of rotation AL arm length direction AB arm width direction α angle of inclination β angle of inclination γ opening angle QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] DE 10 2020 206 949 A1 [0005, 0018] DE 10 2022 201 621 A1

[0005] DE 10 2022 201

[0018] WO 2020 / 249555 A1

[0021]

Claims

[1] Electric motor (2), in particular a steering motor for a motor vehicle, comprising - a stator (6) with a cylindrical stator base body (18) with radially inwardly directed stator teeth (20) and with a number of first axial grooves (30) formed circumferentially in the stator base body (18), - a motor housing (4) for receiving the stator (6), wherein a number of second axial grooves (50) are provided on an inner wall (58) of the housing, which are arranged in alignment with the first axial grooves (30), - at least one spring element (34) which has a spring base body (36) which is or can be inserted radially in a form-fitting manner into one of the first axial grooves (18), and at least one spring arm (38) which is flared or bent out from the spring base body (36) and projects radially beyond the stator base body (18) on the circumferential side, - wherein the spring arm (38) has a stiffening contour (62) along an arm longitudinal direction (AL), which increases a tangential stiffness of the spring arm (38), and - wherein the spring arm (38) engages at least partially radially and tangentially in a form-fitting manner in one of the second axial grooves (50) on the free end side. [2] Electric motor (2) according to claim 1, characterized by that the second axial grooves (50) are introduced into the housing inner wall (58) by a joining process of the stator (6) into the motor housing (4). [3] Electric motor (2) according to claim 1 or 2, characterized by that the stiffening contour (64) is designed such that a tangential supporting force (72) in the second axial groove (50) is at least partially converted into a radial force (74) acting along the spring arm (38). [4] Electric motor (2) according to one of claims 1 to 3, characterized bythat the stiffening contour (62) is substantially V-shaped or U-shaped in cross section, the stiffening legs (62) formed thereby forming the contact surface in the second axial groove (50). [5] Electric motor (2) according to one of claims 1 to 4, characterized by that the spring arm (38) has a convex bend on the free end with respect to the second axial groove (50) as a contact surface. [6] Electric motor (2) according to claim 5, characterized by that the stiffening contour (62) extends over the bend. [7] Electric motor (2) according to one of claims 1 to 6, characterized by that the spring element (34) is designed as a one-piece stamped and bent part. [8] Electric motor (2) according to one of claims 1 to 7, characterized by that the stiffening contour (62) is introduced as an embossing into the spring arm (38). [9] Electric motor (2) according to one of claims 1 to 8, characterized bythat the spring element (34) has a coupling spring (40) on a narrow side of the spring base body (36), which projects axially from the first axial groove (30) and which is resiliently supported on the free end side on a housing cover (16) of the motor housing (4). [10] Spring element (34) for an electric motor (2) according to one of claims 1 to 9, comprising - a spring base body (36), and - at least one spring arm (38) extended or bent out from the spring base body (36), - wherein the spring arm (38) has a stiffening contour (62) along an arm longitudinal direction (AL), which increases a tangential stiffness of the spring arm (38).

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