ELECTRIC MACHINE

Description

[0001] The invention relates to an electrical machine, in particular an electric motor.

[0002] Electrical machines, especially electric motors, are typically designed as internal rotor or external rotor motors. This describes the arrangement of the rotor, which is set in rotation by alternating magnetic fields, relative to the stator, which generates these magnetic fields. In an internal rotor motor, this rotor (also called the "rotor") is arranged coaxially with and radially within the stator. In an external rotor motor, the rotor, in turn, rotates around the stationary stator, in particular, enclosing it in a tubular manner.

[0003] Electrical machines, specifically electric motors, are typically encased in a housing that, on the one hand, provides protection against environmental influences (and, particularly in the case of external rotor motors, prevents access to rotating parts) and, on the other hand, also provides attachment points for other components. Such components include, for example, gears connected to the rotor on the output side or other driven elements, such as indirectly or directly driven pumps, motor electronics, or the like. To save installation space, internal rotor motors can also be designed essentially without a housing, at least without a tubular housing surrounding the stator, at least in sections. For example, such an internal rotor motor can also be flooded with a liquid, in particular oil (e.g. for cooling purposes).In this (housing-less) case, fastening points are arranged on the stator, which is usually formed by a laminated core, to which, for example, the downstream gearbox and / or bearing shields arranged on the front side of the stator can be connected.

[0004] In such a case, the motor electronics are often spatially separated from the assembly formed by the stator and the components described above and are connected to this assembly via a cable harness.

[0005] In WO 2008 / 019818 A1 describes a stator assembly for a pump unit, comprising a stator housing and a stator arranged therein. At least one locking element is provided, by means of which the stator is fixed in the stator housing.

[0006] In WO 2009 / 083363 A2 describes an electric motor comprising a stator formed by stacking laminations, a rotor, and a front bearing plate and a rear bearing plate mounted on the front and rear sides of the stator to support the rotor. The front and rear bearing plates are separately attached to the stator stack without being secured to each other by fasteners, making the distance between the bearing housings arranged in the bearing plates and supporting the rotor independent of the variability of the stator stack height.

[0007] DE 25 46 666 describes an electrical machine with a stator made of sheet metal held together by fasteners, a rotor, and bearing flanges provided with mounting lugs welded to the circumference of the stator. The mounting lugs of the bearing flanges are attached to the fasteners in an approximately radial alignment.

[0008] The invention is based on the object of providing an improved electrical machine.

[0009] This object is achieved according to the invention by an electrical machine having the features of claim 1. Advantageous and partly inventive embodiments and developments of the invention are set out in the subclaims and the following description.

[0010] The electrical machine according to the invention is designed as an internal rotor (motor) and preferably represents an electric motor. The electrical machine comprises a stator core and a functional carrier arranged on the rear side (also referred to as the B side) facing away from the output side (hereinafter also referred to as the A side) of the stator core. The functional carrier has a plastic housing in which a circuit carrier is arranged. This circuit carrier, with electronic components arranged thereon, preferably forms a motor control (or "control electronics") of the electrical machine. Furthermore, the functional carrier comprises connecting means integrated into the plastic housing and protruding therefrom in the axial direction of the stator core.The functional carrier is connected to the stator laminated core in an axial direction by means of these connecting means in a form-fitting and / or material-fitting manner on an outer surface of the stator laminated core.

[0011] The material connection is designed in such a way that no fastening elements that have to be mounted separately, in particular no additional elements that protrude in the radial direction (in particular screws or the like) are used.

[0012] Because the functional carrier is directly connected to the stator core, a stator housing surrounding the stator core on its outer surface, to which the functional carrier is also attached, is advantageously eliminated. This allows the electric machine to be manufactured compactly and, advantageously, cost-effectively.

[0013] In the event that the motor control is integrated into the plastic housing of the functional carrier, an additional interface for the spatially extensive (electrical and possibly also mechanical) connection between the stator laminated core and the motor control can also be omitted.

[0014] In In a preferred embodiment, the functional carrier is centered radially relative to the stator laminated core.

[0015] Particularly preferably, the functional carrier is centered relative to the stator core or a so-called B-side bearing plate arranged on the rear side of the stator core by means of centering ribs (or webs) formed (preferably injection-molded) particularly on the plastic housing. Additionally or alternatively, the centering is achieved by means of the connecting means (in particular relative to the stator core).

[0016] The connecting elements are formed by several metal tabs that are injection-molded into the plastic housing of the functional carrier. The plastic housing is therefore injection-molded from a thermoplastic, and the metal tabs form so-called inserts that are overmolded with the plastic of the plastic housing. The metal tabs are preferably comparatively flat – or thin – tabs made of sheet metal, with their flat side resting against the stator laminated core, specifically against its outer shell surface. Furthermore, the metal tabs are welded to the outer shell surface of the stator laminated core. This results in a space-saving design of the electrical machine in the radial direction of the stator laminated core. Furthermore, additional connecting elements, such as screws and / or nuts, are no longer required.

[0017] Alternatively, the metal tabs are not overmolded in the plastic, but are subsequently pressed into the plastic housing, sunk into the plastic housing using ultrasound, or similar.

[0018] The stator lamination stack has a radially protruding contact surface for each metal tab. Preferably, the respective radially protruding contact surface is designed as a type of plateau that protrudes beyond the main body of the stator lamination stack.

[0019] Furthermore, the metal tabs are formed by axially angled "rays" or "arms" of a one-piece, star-shaped sheet metal stamping. The center, where the rays converge, of this sheet metal stamping is positioned at the end face of the stator core (preferably perpendicular to the rotor's rotation axis). This one-piece design of the metal tabs simplifies the production of the functional carrier, specifically the positioning and injection molding of the metal tabs into the plastic housing.

[0020] In In a practical design, the functional carrier is axially mounted against the stator lamination stack or the B-side bearing plate. For this purpose, the functional carrier and / or the stator lamination stack or the B-side bearing plate preferably has a corresponding stop surface. This allows the axial position of the functional carrier relative to the stator lamination stack to be easily specified.

[0021] In In an alternative design, the functional carrier is spaced apart from the rear of the stator laminated core or the B-side bearing plate, viewed in the axial direction. In this case, in a practical variant, the functional carrier is first pushed onto the B-side bearing plate or the stator laminated core during assembly of the electrical machine until it stops and is then slightly retracted by a predetermined distance. Optionally, in this case, catch hooks or similar locking structures—for example, an eyelet, notches, or the like—are formed in the metal tabs, with which the respective metal tab catches on a catch structure, such as a pin or the like, preferably arranged on the contact surface of the stator laminated core.In particular, in this case, the functional carrier with the respective metal tab is initially pushed "too far" over this pin, so that when the functional carrier is pulled back, it gets caught in the catch hook-like structure of the respective metal tab when the intended distance between the functional carrier and the stator laminated core is reached.

[0022] In a preferred embodiment, the electric machine also comprises the B-side bearing shield described above. The B-side bearing shield is made of metal (in particular a metal sheet) and has mounting tabs - in particular also bent in the axial direction - which rest on the outer shell of the stator laminated core and are welded to it. These mounting tabs are preferably arranged below the metal tabs of the function carrier - i.e. between the outer shell surface and the metal tabs. Particularly preferably, these mounting tabs extend in the axial direction over the outer shell surface of the stator laminated core for a shorter distance than the metal tabs of the function carrier. In addition, the mounting tabs lie in a gap predetermined by the radially projecting contact surface of the stator laminated core (provided for the metal tabs).This advantageously allows the metal tabs of the functional carrier and the mounting tabs of the bearing shield to be welded to the stator core in a single manufacturing step. This further simplifies the production of the electric motor.

[0023] In a further preferred embodiment, the stator core, in its intended final assembly state, is free of a stator housing surrounding the stator core on its circumference. The mounting tabs or metal tabs resting on the outer surface of the casing extend, at least in the circumferential direction, only locally over the outer surface of the stator core and therefore do not constitute such a stator housing.

[0024] In an alternative embodiment constituting an independent invention, the functional carrier is connected to the stator laminated core only in a form-fitting manner, in particular by means of a locking or snap connection.

[0025] For this purpose, the metal tabs described above have, for example, incisions or projections extending in the circumferential direction, which engage with projections projecting in particular radially from the stator laminated core.

[0026] Alternatively, slightly offset projections or recesses are formed on or in the stator lamination stack from one lamination layer to the next. These interact with corresponding, stepped or tooth-like offset projections or a stepped groove in the metal tab or a plastic retaining tab of the plastic housing. The projections or recesses interlock according to the lock-and-key principle, optionally with slight elastic deformation.

[0027] Alternatively, the plastic housing (e.g., the metal tab or a one-piece retaining tab that axially extends over the stator core) has at least one pocket on a side facing the stator core. A T-shaped pin is formed on the stator core or the B-side bearing plate, which accommodates a spring wire clip. The spring wire clip is pushed toward the functional carrier until the smallest possible shoulder of the clip rests in an undercut in the pocket.

[0028] Alternatively, the plastic housing has a number of clips that are slid over a T-shaped post on the outer surface of the stator core or the B-side bearing plate. One of the clips, particularly a slot therein, engages with the post and forms a positive fit in the circumferential direction of the stator core. For axial fixation, the T-shaped post is then deformed in the radial direction, clamping the clip in place.

[0029] The conjunction "and / or" is to be understood here and in the following in particular in such a way that the features linked by this conjunction can be formed both together and as alternatives to one another.

[0030] An exemplary embodiment of the invention is illustrated in more detail below with reference to a drawing. In the drawings: Fig. 1 in a schematic perspective view of an electrical machine, Fig. 2 in a further schematic perspective view of the electrical machine in a partially assembled state, Fig. 3 in a further schematic perspective view of the electrical machine in a partially assembled state, Fig. 4 in a further schematic perspective view of the electrical machine in a partially assembled state with partially hidden components, and Fig. 5 in view according to Fig. 4 the electrical machine in a further partially assembled state.

[0031] Corresponding parts are always provided with the same reference symbols in all figures.

[0032] In Fig. 1 is an electrical machine, hereinafter referred to as electric motor 1, shown schematically. The electric motor 1 has a stator core 2, which is part of a stator 3 (see Fig.2 ). In addition to the stator core 2, the stator 3 also has stator windings 4 formed from an electrically conductive wire. These stator windings 4 are wound on an inner side of the essentially tubular stator core 2 via "teeth 5" of the stator core 4. The electric motor 1 also has - as in Fig. 2 can be seen - a rotor 6 arranged radially on the inside of the stator laminated core 2, which has a gear 10 on an output side, hereinafter also referred to as the A side 8 of the electric motor 1, for coupling to a gear not shown in detail, arranged downstream of the electric motor 1 on the output side.

[0033] In Fig. 1 A portion of a gear housing 12 for this gearbox is shown. This gear housing 12 is flanged to the electric motor 1 on the A-side 8. Between the gear housing 12 and the stator 3, an A-side bearing plate 14 is arranged, which supports a bearing (not shown in detail) for the rotor 6. On a B-side 16 opposite (or facing away from) the A-side 8 (or "rear side", see Fig. 4 ) a B-side bearing shield 18 is arranged, which has a radial bearing 20 for the rotor 6, specifically for a rotor shaft 22 of the rotor 6.

[0034] The electric motor 1 also has a functional carrier 24, which is arranged on the B-side 16 on the stator 3, specifically on the stator laminated core 2. The functional carrier 24 comprises an injection-molded plastic housing 26, which provides a front-end housing interior 28 for a circuit board 32 equipped with electronic components 30. This circuit board 32, together with the electronic components 30, forms control electronics, referred to as motor control for the electric motor 1. In addition, a plug connection 34 for a Fig. 2 indicated wiring harness 36. This wiring harness 36 serves to supply power and control signals to the electric motor 1.

[0035] The electric motor 1 is designed as a stator-housingless motor. This means that the stator 3 is not enclosed by a housing on its outer shell 42. To support the A-side bearing plate 14 and the downstream gear housing 12, flange wings 40 are formed on the stator lamination stack 2. These flange wings 40 are formed by radial projections on only a portion of the stator laminations (not shown in detail) forming the stator lamination stack 2.

[0036] In order to keep the radial structure of the electric motor 1 as small as possible, particularly in the area of ​​the stator 3, the function carrier 24 and the B-side bearing shield 18 are not screwed to the stator laminated core 2 or fixed to it by means of other additional connecting elements. Instead, the function carrier 24 has four metal tabs 50 as connecting means, which are formed from a sheet metal that is thin-walled compared to the diameter of the stator 3. These metal tabs 50 are injection-molded into the plastic housing 26 of the function carrier 24 and lie flat against the outer shell surface 42, specifically against the contact surfaces 52 of the stator laminated core 2, which are raised by approximately the thickness of a sheet metal forming the B-side bearing shield 18. The metal tabs 50 are welded onto the contact surfaces 52 of the stator laminated core 2.

[0037] As in Fig. 4As shown in more detail, the metal tabs 50 are each formed by a ray or arm of a star-shaped or X-shaped sheet metal stamping 54. This sheet metal stamping 54 lies with its center on the end face of the stator 3 in the plastic housing 26 of the function carrier 24. The metal tabs 50 are angled from the center of the sheet metal stamping 54 parallel to the rotor axis 22 and the outer surface 42 of the stator 3. A keyhole-like elongated hole 56 is also provided at the free end of each metal tab 50.

[0038] Within this elongated hole 56, the respective metal tab 50 is welded to the contact surface 52 of the stator laminated core 2.

[0039] For assembly, the functional carrier 24 is pushed against the B-side bearing shield 18 using a stop (not shown) formed on the inside of the plastic housing 76, and the metal tabs 50 are then welded. To center the functional carrier 24 relative to the stator 3, the plastic housing 26 of the functional carrier 24 has centering ribs (not shown in detail), which are brought into contact with an area of ​​the B-side bearing shield 18 that is shaped as precisely as possible with respect to its outer diameter.

[0040] The B-side bearing shield 18, similar to the metal tabs 50, has angled mounting tabs 60 parallel to the outer shell surface 42, which are arranged radially inside the metal tabs 50, i.e. below the metal tabs 50 and are brought into contact with the outer shell surface 42. The mounting tabs 60 are welded to the outer shell surface 42 of the stator laminated core 2 through the keyhole-like slot 56 in the metal tabs 50. Because the mounting tabs 60 are arranged below the metal tabs 50, the circumferentially arranged space between the mounting tabs 60 and the metal tabs 50 can be used, for example, to form electrical connections between the motor control and the stator 3. The B-side bearing shield 18 also has two flange tabs 62 which are screwed to the flange wings 40. List of reference symbols

[0041] 1 Electric motor 2 Stator laminated core 3 Stator 4 Stator winding 5 Tooth 6 Rotor 8 A-side 10 Gear 12 Gearbox housing 14 Bearing shield 16 B-side 18 Bearing shield 20 Radial bearing 22 Rotor shaft 24 Function carrier 26 Plastic housing 28 Housing interior 30 Component 32 Circuit board 34 Plug-in connection 36 Cable harness 40 Flange wing 42 Shell outer surface 50 Metal tab 52 Contact surface 54 Sheet metal stamping 56 Slotted hole 60 Mounting tab 62 Flange tab

Claims

1. Electric machine (1) which is in the form of an internal rotor and which has a laminated stator core (2) and a functional support (24) which is arranged on a rear side (16) that is remote from an output side (8) of the laminated stator core (2), wherein the functional support (24) comprises a plastics housing (26) in which there is arranged an interconnect device and connecting means (50) which are integrated into the plastics housing (26) and protrude therefrom in the axial direction of the laminated stator core (2), wherein the functional support (24) is connected by means of the connecting means (50) to the laminated stator core (2) at a lateral outer surface (42) of the laminated stator core (2) by substance-to-substance bonding in the axial direction, wherein the connecting means are formed by a plurality of metal lugs (50) which are embedded into the plastics housing (26) by injection moulding or are subsequently pressed into the plastics housing (26) or sunk into the plastics housing by means of ultrasound, and wherein the metal lugs (50) are welded to the laminated stator core (2) on the lateral outer surface (42) thereof, wherein the laminated stator core (2) has a radially protruding contact surface (52) for each metal lug (50), and wherein the metal lugs (50) are formed by beams, which are bent in the axial direction, of a one-piece, star-shaped stamped sheet-metal part (54), the centre of which is arranged at the end face relative to the laminated stator core (2).

2. Electric machine (1) according to Claim 1, wherein the functional support (24) is centred radially relative to the laminated stator core (2).

3. Electric machine (1) according to Claim 2, wherein the functional support (24) is centred relative to the laminated stator core (2) or a B-side bearing plate (18) arranged on the rear side (16) thereof by means of centring ribs and / or by means of the connecting means (50).

4. Electric machine (1) according to one of Claims 1 to 3, wherein the functional support (24) abuts the laminated stator core (2) or the B-side bearing plate (18) in the axial direction.

5. Electric machine (1) according to one of Claims 1 to 4, wherein the functional support (24) is spaced apart in the axial direction from the rear side (16) of the laminated stator core (2) or from the B-side bearing plate (18).

6. Electric machine (1) according to one of Claims 1 to 5, having the B-side bearing plate (18), wherein the B-side bearing plate (18) is manufactured from metal and has mounting lugs (60) which lie against the lateral outer surface (42) of the laminated stator core (2) and are welded thereto.

7. Electric machine (1) according to one of Claims 1 to 6, wherein the laminated stator core (2), in the intended final mounted state, is free of a stator housing surrounding the laminated stator core (2) on the circumferential side.