Method for producing electric motor stator

Abstract

The invention relates to a method for producing an electric motor stator having a yoke ring and a pole star ring having a plurality of stator teeth for arranging windings, preferably winding assemblies, the pole star ring being receivable in the yoke ring and being inserted into the yoke ring, wherein the stator teeth face the yoke ring, and wherein the pole star ring expands, whereby the stator teeth are pressed against the yoke ring. The invention further relates to an electric motor stator having a yoke ring and a pole star ring which can be accommodated in the yoke ring and which has a plurality of stator teeth for arranging windings and openings for arranging a rotor, the stator teeth of the pole star ring being connected to one another by means of an expandable connection, the connector is plastically deformed in the installed state.

Description

[0001] The present invention relates to a method for manufacturing a stator of an electric motor, the stator having a yoke ring and a pole star ring, the pole star ring having a plurality of stator teeth for arranging windings, preferably winding assemblies, wherein the pole star ring is inserted into the yoke ring. Furthermore, the present invention relates to such a stator of an electric motor, the stator having a yoke ring and a pole star ring, the pole star ring being capable of being received in the yoke ring and having a plurality of stator teeth for arranging windings and an opening for arranging a rotor.

[0002] Conventional electric motors have a stator and a rotor, the stator forming the stationary motor part and the rotor forming the rotating motor part. In the case of an internal rotor, the stator is usually provided with a stator yoke, and stator teeth project radially inwards on the stator yoke. The stator teeth have pole shoes at the ends facing the rotor and are provided with windings that generate an electromagnetic field during operation. In order to form and enhance the electromagnetic field, the stator yoke with stator teeth is usually made of a soft magnetic material, for example, in the form of a laminated core.

[0003] When manufacturing the stator yoke, it is not possible to apply the windings from the outside through the closed yoke ring, and from the inside, the pole shoes make it difficult to access the stator teeth. Therefore, for an integral stator yoke, complex winding methods are required to provide the required windings for the stator teeth. Therefore, when manufacturing the stator of an electric motor, it is known to use a multi-part structure of the stator, where there are very different embodiments, such as a stator composed of C-shaped segments, a stator yoke ring with individual stator teeth to be attached to the stator, or a two-part stator with a pole star ring and a cylindrical yoke ring. With these multi-part stator concepts, the windings can be easily applied directly to the stator teeth.

[0004] Both the pole star ring and the cylindrical yoke ring of the two-part stator are usually made of a plurality of individual metal sheet elements, which are arranged stacked one above the other in the axial direction and joined together by stamping, gluing, welding, paint coating or other stacking processes to form a stack. For example, in US2002 / 0083572 A1, the loosely stacked stator laminations are aligned using an expanding mandrel and then fixed in the motor housing by a threaded connection. The windings are wound around or pushed onto the freely accessible stator teeth of the pole star ring as a winding assembly. After the windings are installed on the pole teeth accessible from the outside, the pole star ring is joined by pressing or shrinking. For the press connection between the pole star ring and the yoke ring, manufacturing tolerances may result in an air gap between the stator teeth and the yoke ring, leading to magnetic losses in the stator and deformation of the stator teeth, and thus rendering the stator scrapped.

[0005] In a two-part stator known from the prior art having a pole star ring and a yoke ring, when the components are joined together, the pole star ring is axially pressed into the yoke ring. Mechanical contact of the components during axial pressing may produce notches and gaps in the components, which can have a negative impact on the operation of the electric motor. In addition, separation may occur in the laminated cores of the pole star ring and the yoke ring, which means that the laminations no longer lie flat against each other, resulting in magnetic losses in the stator. Furthermore, during axial pressing, the pole star ring and the yoke ring are required to have precise profiles and strict tolerances to avoid an air gap between the stator teeth and the yoke ring or to ensure a consistent outer diameter of the yoke ring.

[0006] For example, it is known from DE 10 2015 000 769 A1 that there is an electric motor stator having an interference or friction press fit connection between the stator teeth of the pole star ring and the yoke ring, where the yoke ring is axially pressed onto the pole star ring and in addition a material bond is formed by microencapsulated adhesive. In DE 10 2016 201 967 A1, in order to manufacture the stator in a reliable manner, a tangential press fit connection between the stator teeth of the pole star ring and the yoke ring is described, where the stator teeth are designed with trough-shaped elastic recesses and are inserted into the axial grooves of the yoke ring in order to achieve a press fit with the yoke ring by means of tangential forces.

[0007] Therefore, the object of the present invention is to provide an improved method for manufacturing an electric motor stator that simplifies the manufacture and installation of the pole star ring and the yoke ring, while also reducing waste and ensuring that the stator has a functionally reliable quality.

[0008] The basic object of the present invention is achieved by the following method for manufacturing an electric motor stator: providing a yoke ring and a pole star ring having a plurality of stator teeth for arranging windings, preferably winding assemblies, wherein the pole star ring can be received in the yoke ring; inserting the pole star ring into the yoke ring, wherein the stator teeth face the yoke ring; and expanding the pole star ring, wherein the stator teeth are pressed against the yoke ring. This method enables a reliable and notch-free arrangement of the pole star ring in the yoke ring. It is reasonable to arrange the windings on the stator teeth before inserting the pole star ring, and individual prefabricated winding assemblies can be pushed onto the stator teeth from the outside. In order to form the pole star ring, the individual stator teeth are connected to each other in the region of the inner pole shoe, for example, by plastically deformable elements, preferably by stretchable connecting pieces. When the pole star ring is inserted into the yoke ring, the stator teeth are arranged in the yoke ring with very little or zero mechanical stress, so that neither notches nor gaps or separations occur in the stator teeth or the laminated core of the yoke ring. The ends of the stator teeth remote from the pole shoe then face the inner circumferential surface of the yoke ring in the radial direction. It is advisable to first place the yoke ring in a thick-walled support ring and then expand the pole star ring arranged therein, so that the yoke ring does not expand or deform due to the radial pressing force during expansion. Due to the forces acting on the stator teeth in the radial direction, the free ends of the stator teeth are pressed against the yoke ring, resulting in a press fit between the pole star ring and the yoke ring. When the pole star ring expands, the deformable elements between the stator teeth are stretched, elongated or bent.

[0009] An advantageous embodiment provides that the pole star ring has an opening with an inner diameter for arranging the rotor, and expanding the pole star ring enlarges the inner diameter of the opening. Through this central opening of the pole star ring, radial forces can be applied safely and easily to expand the pole star ring, wherein the final inner diameter for arranging the rotor in the fully assembled stator is only achieved after the pole star ring has been expanded. For a fault-free and efficient electric motor, a uniform distance between the stator teeth or pole shoes and the rotor is necessary, which is why all the stator teeth are pressed against the yoke ring as evenly as possible.

[0010] In an advantageous variant of the method, one or more inwardly projecting connecting pieces are provided in the spaces between the individual stator teeth to form the pole star ring, wherein, by applying pressure to the connecting pieces, the connecting pieces are straightened and the pole star ring is thereby expanded. By applying force to the connecting pieces, they can be deformed and / or straightened. This enlarges the inner diameter of the opening of the pole star ring, thereby pressing the stator teeth against the yoke ring. The deformation can be carried out plastically without heating, which reduces the complexity of the manufacturing process. In addition, the magnetic permeability of the connecting pieces is reduced, thereby reducing the unwanted magnetic flux on the connecting pieces.

[0011] An advantageous embodiment provides that the yoke ring on the inner circumferential surface has a plurality of recesses for receiving the stator teeth of the pole star ring, and the stator teeth are pressed into the recesses when the pole star ring expands. This enables the ends of the stator teeth to be permanently fixed to the inner circumferential surface of the yoke ring by a tangential holding force. The recesses on the inner circumferential surface can be designed as axial grooves, where the radially deeper grooves and the small remaining gap between the yoke ring and the stator teeth result in less dispersion of the bite torque between the individual teeth and the yoke ring. By providing the recesses and pressing the stator teeth into the recesses, the stator teeth can also be precisely positioned in the stator, thereby improving the efficiency of the electric motor.

[0012] An improved version of this method provides that an expansion tool, preferably an expansion tool with a wedge-shaped expansion element, is inserted into the pole star ring in order to expand the pole star ring. Preferably, the expansion tool is inserted into the pole star ring after the pole star ring has been inserted into the yoke ring. Using a suitable expansion tool enables the pole star ring to be expanded uniformly and thus also ensures a good and uniform connection between the plurality of stator teeth and the yoke ring. A practical design provides that the expansion tool is inserted into the rotor opening of the pole star ring in the axial direction and stretched uniformly in the radial direction there, in order to expand the pole star ring uniformly by applying a radial force. The wedge-shaped expansion element can include a conical cone that is inserted into an expandable conical cylinder. The deeper the conical cone is inserted into the conical cylinder, the larger the outer circumference of the conical cylinder, where the cylindrical outer surface of the conical cylinder presses against the pole star ring or the connecting member of the pole star ring. Due to the cylindrical outer shape, the contact force is evenly distributed over the entire axial length of the stator. The contact pressure is applied at a right angle to the axis of rotation of the motor or the rotor.

[0013] In a special variant, the expansion tool has a plurality of radially movable struts, preferably, for each stator tooth, one strut is assigned to the stator tooth, and the struts are pressed radially outwards in order to expand the pole star ring. The radial force of the expansion tool is directly applied to the individual stator teeth by the struts pressing against the stator teeth in the middle. If a uniform radial force is applied to all the stator teeth of the pole star ring simultaneously, it will result in a uniform contact pressure of all the stator teeth against the yoke ring.

[0014] An alternative method variant provides that one or more inwardly protruding connecting elements are arranged in the spaces between individual stator teeth to form a pole star ring, and the expanding tool has a plurality of radially movable struts, preferably one strut being assigned to each space between individual stator teeth, wherein the struts are pressed radially outwards in order to straighten the connecting elements and thereby expand the pole star ring. In the spaces between individual stator teeth, one or more connecting elements, preferably bent connecting elements, may be arranged, wherein the radially movable struts of the expanding tool bear essentially against all the connecting elements of the space and press them outwards. In order to expand the pole star ring, the struts of the expanding tool are positioned essentially centrally between the stator teeth in order to press as evenly as possible against the respective connecting elements. By bending the connecting elements and / or straightening previously bent connecting elements, the magnetic permeability of the material of the connecting elements is reduced because the material saturates more quickly after the bending process. The reduction of the magnetic permeability at the connecting elements of the individual stator teeth of the pole star ring is advantageous during operation of the electric motor because the tabs between the individual stator teeth would form an undesired magnetic short circuit.

[0015] In an advantageous variant of the method, the connecting elements are removed after expansion of the pole star ring, in particular by laser beam cutting or vaporization underwater. This prevents a magnetic short circuit from occurring between the stator teeth, thereby enabling a higher torque to be achieved. Since the connecting elements are close to the winding assembly, the connecting elements can only be removed to a limited extent by stamping or mechanical cutting.

[0016] A possible design provides that the expanding tool has an axially movable working wedge and the struts of the expanding tool have wedge-shaped pressing surfaces. By means of a conical enlargement, the axially movable working wedge which can be moved in the axial direction towards the rotor opening, a uniform radial force can be applied via the wedge-shaped pressing surfaces of the struts to the connecting elements of the stator teeth or the pole star ring, such that the stator teeth are pressed evenly outwards and against the yoke ring by the axially movable working wedge.

[0017] Furthermore, the invention relates to an electric motor stator having: a yoke ring, preferably a cylindrical yoke ring; a pole star ring which can be received in the yoke ring and has a plurality of stator teeth and rotor openings; and a winding, preferably a winding assembly, which is arranged on the stator teeth. According to the invention, the stator teeth of the pole star ring are connected to each other by stretchable connectors, wherein the connectors are plastically deformed in the installed state compared to the original state of the stator, and the stator teeth are pressed against the yoke ring compared to the original state. In its original or pre-installed state, the stator is unassembled in individual parts not attached to each other. This enables precise alignment and reliable arrangement of the stator teeth on the yoke ring, wherein the stator teeth and / or pole shoes have the same radius and / or are equidistant from the rotor axis inwardly, such that an as-uniform-as-possible air gap with the rotor can be ensured later in the electric motor. This not only improves the efficiency of the electric motor by the precise positioning of the stator teeth in the yoke ring, but also reduces manufacturing waste and the sensitivity of the electric motor to defects by avoiding notches, deformations and separations in the laminated core during stator manufacturing. The stretchable connectors between the individual stator teeth of the pole star ring, in particular plastically deformable connectors (the deformation of which is not reversible or not fully reversible after the application of a radial force), enable the pole star ring to be quickly and easily positioned in the yoke ring before the application of a radial force, uniformly expand the pole star ring, and press the stator teeth against the yoke ring by the application of a radial force. This enables the safe and rapid manufacture of the stator, thereby saving costs, and a permanent press fit is formed between the stator teeth of the stator and the inner circumferential surface of the yoke ring. The connectors also enable magnetic short-circuiting between the stator teeth, whereby existing torque fluctuations can be reduced depending on the wiring, pole pairs and number of teeth of the electric motor.

[0018] In order to give the stator good magnetic permeability, the pole star ring can be designed as a set of stator laminations, wherein the individual stator laminations are designed as lamination rings which extend over all the stator teeth of the pole star ring and form stretchable connectors between the stator teeth. This not only enables good magnetic permeability of the stator teeth, but also enables the simple formation of stretchable connectors. The stator laminations can be designed as blanks or punched-out lamination rings and can be joined by stamping, gluing, welding, bonding, etc. to form a lamination group. At least three stator laminations of the pole star ring can be designed as lamination rings, wherein the lamination rings are preferably evenly distributed over the thickness of the lamination group. For example, every fifth, tenth or twentieth stator lamination of the lamination group can be designed as a lamination ring in order to give the pole star ring a corresponding functional reliability. In an alternative form, all the stator laminations of the lamination group can also be designed as thin connectors which form the closure of the stator in the direction of the rotor openings after expanding the pole star ring and pressing the stator teeth onto the yoke ring, and can enable all the winding cavities between the closed pole star ring and the yoke ring to be potted without additional internal sealing.

[0019] Advantageously, the stretchable connecting element can be designed as a bent connecting element, preferably having a bend in the radial direction. This provides sufficient stretchability to expand the pole star ring, as well as the ability to plastically deform to ensure sufficient stability of the pole star ring when inserted into the yoke ring, and after expansion, to press the stator teeth onto the yoke ring. Generally, the bent connecting elements between the stator teeth are located at the inner ends of the stator teeth and / or pole shoes and have an outwardly bent portion.

[0020] In an alternative form, the stretchable connecting element can also be designed as a connecting element that is bent in the radial direction and bent towards the opening, where these inwardly bent connecting elements project particularly into the central opening of the pole star ring in the pre-installed state. Inwardly bent means bent towards the center of the stator or the pole star ring. The center of the stator lies on the axis of rotation of the motor or the rotor. These inwardly bent connecting elements are directly stretched or straightened by the struts of the expansion tool during expansion, thereby significantly reducing the magnetic permeability of the connecting element. The connecting element has a certain degree of rigidity. When pressed against the stator teeth, the connecting element is stretched. Once the pressure on the stator teeth is reduced, the connecting element partially rebounds to its original shape. When the strut of the expansion tool is pressed onto the connecting element, the contact pressure directly deforms the connecting element. This reduces the rebound of the material or the connecting element after the removal of the expansion tool. More precisely, this defines the radius inside the stator in which the motor rotor rotates. Pressure is applied to the connecting element to bend it to a predefined position and thus to the defined inner diameter of the opening. The inner diameter of the opening corresponds to the inner radius of the stator. Due to the small tolerance of the inner diameter, a larger rotor can be inserted into the stator, which allows for a smaller air gap between the stator and the rotor, thereby achieving a larger torque.

[0021] Preferably, the connecting element has a break notch. In particular, the break notch can be punched out. Due to the tensile stress or bending stress during expansion, the connecting element may break during the expansion movement. For this purpose, the radial expansion movement of the expansion tool can be increased. The break of the connecting element prevents a magnetic connection or magnetic short circuit between the stator teeth and increases the possible torque.

[0022] One available implementation provides that the yoke ring has a plurality of recesses distributed on the inner circumferential surface for accommodating the radial ends of the stator teeth. By providing recesses that are substantially evenly distributed, the stator teeth can be evenly arranged and more precisely positioned during stator manufacturing. In particular, these recesses distributed on the inner circumferential surface of the yoke ring can be designed as grooves extending in the axial direction. The shape of the yoke ring is preferably cylindrical. The lateral edges of the grooves can enable more precise positioning of the stator teeth, and at the same time, a tangential press fit can be achieved between the edges of the grooves and the radial ends of the stator teeth, and the effect is enhanced as the depth of the grooves increases. The shape of the radial ends of the stator teeth can also be rectangular so as to be firmly held in the grooves by the tangential press fit and thus firmly connected to the yoke ring. The press fit at the edges of the grooves extending in the axial direction can not only introduce tangential forces onto the stator teeth but also enable the stator teeth to be precisely aligned in the direction of the rotor axis. In this design, the stretchable connecting member is only used to position the stator teeth relative to the yoke ring when inserting and expanding the pole star ring. Once the stator teeth are firmly pressed into the grooves on the inner circumferential surface of the yoke ring, the stretchable connecting member between the individual stator teeth can be removed after the pole star ring is expanded, because the stator teeth are firmly positioned in the grooves and connected to the yoke ring by the tangential press fit. In this advantageous design, the magnetic short circuit between the stator teeth is eliminated, enabling higher torque to be achieved. The removal of the connecting member can preferably be carried out by laser beam cutting or vaporization underwater. Since the connecting member is close to the winding assembly, the connecting member can only be removed to a limited extent by stamping or mechanical cutting.

[0023] In the following, non-limiting implementations of the present invention are explained in more detail with reference to the drawings shown by way of example, wherein:

[0024] Figure 1 is a perspective view of a stator pole star ring according to the present invention,

[0025] Figure 2 is Figure 1 a perspective view of the pole star ring and a plurality of individual winding assemblies,

[0026] Figure 3 is a perspective view when the winding assembly is pushed onto the Figure 1 and Figure 2 pole star ring,

[0027] Figure 4 is a perspective view of the pole star ring with the inserted winding assembly and the Figure 3 yoke ring,

[0028] Figure 5 1]is a perspective view of the Figure 4 yoke ring after the pole star ring is inserted,

[0029] Figure 6is a perspective view of a stator according to the present invention with a yoke ring having Figure 4 and Figure 5 and a radially expanded and press-fitted pole star ring Figure 3 ,

[0030] Figure 6a is an enlarged partial cross-sectional view of a stator of Figure 6 with a schematically shown expanding tool,

[0031] Figure 7 is a cross-sectional view of a stator of Figure 6 without a winding assembly and with a schematically shown expanding tool,

[0032] Figure 7a is a cross-sectional view of a stator of Figure 7 without a winding assembly and an expanding tool,

[0033] Figure 8 is a perspective cross-sectional view of a stator of Figure 6 through which an expanding tool is accommodated,

[0034] Figure 8a is a cross-sectional view through Figure 8 the stator and the expanding tool, and

[0035] Figure 9 is an enlarged partial cross-sectional view of another embodiment of a stator according to the present invention with a schematically shown expanding tool.

[0036] Figure 1 shows a perspective view of the pole star ring 1 which, together with the yoke ring 2 and the winding assembly 3, forms a stator 4 according to the present invention. In the embodiment shown, the star-shaped pole star ring 1 is made of a laminated core composed of multiple stator laminations which are stacked one above the other in the axial direction and connected to each other, for example, by stamping together to form a central cylindrical opening 5. After the stator 4 is installed, the rotor of the electric motor is accommodated in the opening 5 and can rotate in the axial direction. The star-shaped pole star ring 1 includes a plurality of radially outwardly extending stator teeth 6 which, when radially positioned inside the cylindrical opening 5, form pole shoes 7 which face the rotor of the electric motor in the installed state. In order to position the stator teeth 6 in the pole star ring 1 and form a closed ring of the pole star ring 1 around the opening 5, the stator teeth 6 are connected to each other in the region of the pole shoes 7 by stretchable connectors 8. In Figure 1 the embodiment of the pole star ring 1 shown, the connector 8 is designed as a radially outwardly bent tab which is formed by a single stator lamination of the pole star ring 1 designed as a laminated core. In the embodiment shown, only a single lamination is provided with the connector 8; for example, only every fifth, tenth or twentieth lamination has the connector 8. The connectors 8 are generally uniformly distributed in the axial direction over the thickness of the stator teeth 8.

[0037] like Figure 2 and Figure 3 As shown, a single prefabricated winding assembly 3 is pushed onto the stator teeth 6 protruding outward in the radial direction, wherein each stator tooth 6 is provided with a winding assembly 3; see Figure 2 . As from Figure 3 It can be seen from the perspective view of the pole star ring 1 in FIG that the winding assembly 3 is pushed completely onto the stator tooth 6 until it touches the pole shoe 7 , so that the radially outwardly projecting end 9 of the stator tooth 6 protrudes slightly from the winding assembly 3 .

[0038] Figure 4 The perspective view in FIG shows the pole star ring 1, wherein the winding assembly 3 is pushed onto the stator teeth 6 and the yoke ring 2 is in the installed position. The yoke ring 2 has a recess 10 on the inner circumference for positioning the stator teeth 6, which recess is designed as a groove 19 extending in the axial direction in this embodiment. In the installed position shown here, each radially protruding end 9 of the stator tooth 6 is aligned with the groove 19 extending in the axial direction on the inner circumference of the yoke ring 2. Similar to the pole star ring 1, the yoke ring 2 can also be manufactured as a laminated core made of layered stator laminations. As shown in FIG. Figure 5 As can be seen in FIG, during installation, the yoke ring 2 is pushed onto the pole star ring 1 in the axial direction, wherein the protruding ends 6 of the stator teeth 6 are guided only through the grooves 19 on the inner circumference of the yoke ring 2, so that no gaps or notches appear in the grooves 19 and the protruding ends 9. A gap 11 remains between the protruding ends 9 and the groove bottom 20 of the groove 19.

[0039] After the pole star ring 1 is positioned in the yoke ring 2, a force acting in the radial direction is applied from the opening 5 to each stator tooth 6 and / or each pole shoe 7 of the stator tooth 6, so that the protruding end 9 of the stator tooth 6 is pressed into the recess 10. Figure 6 As can be seen in FIG, the protruding end 9 of the stator tooth 6 then rests on the groove bottom 20 of the groove 19 , so that the initially existing gap 11 is essentially filled by the protruding end 9 .

[0040] When the pole star ring 1 expands radially and the protruding end 9 is pressed into the recess 10 of the yoke ring 2, the opening 5 expands and the distance between the individual stator teeth 6 increases. Due to the increase in the distance between the stator teeth 6, the stretchable connecting parts 8 between the stator teeth 6 are stretched when the pole star ring 1 expands radially, so that the curvature of the connecting parts 8 is flattened. Since the connecting parts 8 are formed by the stator laminations of the laminated core of the pole star ring 1 in this embodiment, most of the stretching of the connecting parts 8 occurs as plastic deformation. This can also be seen from the Figure 6aIt can be seen from the enlarged partial cross-sectional view showing the expanded polar star ring 1 and the stator teeth 6 pressed into the grooves 19 of the yoke ring 2. By using the expansion tool 12 which is only schematically shown here, a radial force is applied to the stator teeth 6 such that the protruding ends 9 of the stator teeth 6 are firmly pressed into the grooves 19 of the yoke ring 2, where the bending of the connecting member 8 is flattened in order to compensate for the greater distance between the stator teeth 6.

[0041] The press fit between the stator teeth 6 and the yoke ring 2 is basically generated by the tangential force between the side walls of the grooves 19 and the protruding ends 9 of the stator teeth 6. Due to the permanent press fit connection between the stator teeth 6 and the yoke ring 2, after the polar star ring 1 is expanded, the connection formed by the connecting member 8 between the individual stator teeth 6 is no longer required, which is why the connecting member 8 can also be removed after the expansion process. In addition, due to the uniform expansion process and the stator teeth 6 being uniformly pressed into the yoke ring 2, all the stator teeth 6 are basically uniformly pressed outwards by the expansion tool 12 and to the same extent, such that the pole shoes 7 of the stator teeth 6 are all at the same distance from the axial axis. This can be clearly seen in the cross-sectional view of the stator 4 without the winding assembly 3 in Figure 7 and Figure 7a the cross-sectional view of the stator 4 without the winding assembly 3 in

[0042] Figure 8 A perspective cross-sectional view showing the expansion tool 12 through which the stator 4 is arranged is shown. The expansion tool 12 has a thick-walled support ring 13 against which the yoke ring 2 abuts during the expansion and clamping process such that the yoke ring 2 does not expand or bend. In this cross-sectional view, the structure of the stator teeth 6 and / or the polar star ring 1 made of laminated stator laminations stacked in layers can also be seen. The expansion tool 12 has a working wedge 14 which is movable in the axial direction, where the working wedge 14 moves in the axial direction against the pre-tension force of the spring 15 by means of a centrally arranged threaded bolt 16. The tapered flanks of the working wedge 14 act on a plurality of radially movable struts 17 which are held on the working wedge 14 by an elastic ring 18; see also Figure 8a . The force applied in the axial direction by the working wedge 14 is converted into a radial force by the inclined inner flanks of the struts 17, and this radial force acts uniformly on the stator teeth 6 on the straight outer flanks of the struts 17 and presses the stator teeth into the recesses 10 on the yoke ring 2.

[0043] Figure 9Another embodiment of the stator 4 according to the invention and the corresponding manufacturing method are shown, in which an enlarged partial cross-sectional view of the stator 4 and the schematically shown expansion tool 12 are shown. The pole star ring 1 of the stator 4 according to the invention also has a plurality of stator teeth 6, which have inner pole shoes 7 and protruding ends 9. The pole star ring 1 is arranged in the yoke ring 2, and each stator tooth 6 of the pole star ring 1 is provided with a winding assembly 3 previously pushed onto the stator tooth from the outside. The individual stator teeth 6 are provided with plastically deformable connecting elements 8 at the edges of the pole shoes 7 to form the pole star ring 1, wherein the bent portions of the connecting elements 8 protrude inward relative to the pole shoes 7 into the opening 5 of the pole star ring 1. In this variant, the expansion tool 12 generates a radial force that acts on the connecting elements 8 between the individual stator teeth 6 and straightens the connecting elements 8 to expand the pole star ring 1. Thus, the protruding ends 9 of the stator teeth 6 are pressed against the inner peripheral surface of the yoke ring 2 so that the pole star ring 1 or the stator teeth 6 form a permanent press fit with the yoke ring 2. By bending the connecting elements 8, the magnetic permeability of the connecting elements 8 is reduced in order to reduce unwanted magnetic short circuits between the individual stator teeth 6. In this embodiment, depressions 10 or grooves 19 extending in the axial direction can also be provided on the inner peripheral surface of the cylindrical yoke ring 2 in order to precisely position the stator teeth 6.

[0044] List of reference numerals

[0045] 1 Pole star ring

[0046] 2 Yoke ring

[0047] 3 Winding assembly

[0048] 4 Stator

[0049] 5 Opening

[0050] 6 Stator tooth

[0051] 7 Pole shoe

[0052] 8 Connecting element

[0053] 9 Protruding end

[0054] 10 Depression

[0055] 11 Gap

[0056] 12 Expansion tool

[0057] 13 Support ring

[0058] 14 Working wedge

[0059] 15 Spring

[0060] 16 Threaded bolt

[0061] 17 Brace

[0062] 18 Elastic ring

[0063] 19 Groove

[0064] 20 Bottom of the groove

Claims

1. A method for manufacturing an electric motor stator (4), the method having the following steps: - Providing a yoke ring (2) and a pole star ring (1), the pole star ring having a plurality of stator teeth (6) for arranging a winding, preferably a winding assembly (3), wherein the pole star ring (1) can be received in the yoke ring (2); - Inserting the pole star ring (1) into the yoke ring (2), wherein the stator teeth (6) face the yoke ring (2); and - Expanding the pole star ring (1) such that the stator teeth (6) are pressed against the yoke ring (2).

2. The method according to claim 1, wherein the pole star ring (1) has an opening (5) having an inner diameter for arranging a rotor, and expanding the pole star ring (1) enlarges the inner diameter of the opening (5).

3. The method according to claim 1 or 2, wherein one or more inwardly projecting connecting elements (8) are provided in the space between individual stator teeth (6) to form the pole star ring (1), and the pole star ring is expanded by applying pressure on the connecting elements (8).

4. The method according to any one of claims 1 to 3, wherein the yoke ring (2) on its inner circumferential surface has a plurality of recesses (10) for receiving the stator teeth (6) of the pole star ring (1), and when the pole star ring (1) is expanded, the stator teeth (6) are pressed into the recesses (10).

5. The method according to any one of claims 1 to 4, wherein an expanding tool (12), preferably an expanding tool having a wedge-shaped expanding element (14), is introduced into the pole star ring (1) in order to expand the pole star ring (1).

6. The method according to claim 5, wherein the expanding tool (12) has a plurality of radially movable struts (17), preferably, for each stator tooth (6), a strut (17) is assigned to the stator tooth (6), and the struts (17) are pressed radially outwards to expand the pole star ring (1).

7. The method according to claim 5, wherein one or more inwardly projecting connecting elements (8) are provided in the space between the individual stator teeth (6) to form the pole star ring (1), and the expanding tool (12) has a plurality of radially movable struts (17), preferably, for each space between the individual stator teeth (6), a strut (17) is assigned to the space, and the struts (17) are pressed radially outwards in order to straighten the connecting elements (8) and thereby expand the pole star ring (1).

8. The method according to claim 7, wherein the connecting elements (8) are removed after the pole star ring (1) has been expanded, in particular by laser beam cutting or vaporization underwater.

9. An electric motor stator (4), the electric motor stator having: a yoke ring (2), preferably a cylindrical yoke ring (2); a pole star ring (1), the pole star ring being capable of being received in the yoke ring (2) and having a plurality of stator teeth (6) and an opening (5) for arranging a rotor; and a winding, preferably a winding assembly (3), the winding being arranged on the stator teeth, It is characterized in that the stator teeth (6) of the pole star ring (1) being connected to each other by a stretchable connecting piece (8), wherein the connecting piece (8) plastically deforms in the installed state compared to the original state of the stator (4), and the stator teeth (6) are pressed against the yoke ring (2) compared to the original state.

10. The electric motor stator (4) according to claim 9, It is characterized in that the pole star ring (1) being designed as a set of stator laminations, wherein a single stator lamination is designed as a lamination ring, the lamination ring extending over all the stator teeth (6) of the pole star ring (1) and forming the stretchable connecting piece (8) between the stator teeth (6).

11. The electric motor stator (4) according to claim 10, It is characterized in that at least three stator laminations being designed as lamination rings, wherein the lamination rings are preferably evenly distributed over the thickness of the lamination set.

12. The electric motor stator (4) according to any one of claims 8 to 11, It is characterized in that the stretchable connecting piece (8) being designed as a bent connecting piece (8), preferably having a bend in the radial direction.

13. The electric motor stator (4) according to claim 12, It is characterized in that the stretchable connecting piece (8) being designed as a connecting piece (8) that is bent in the radial direction and bent towards the opening (5), wherein the connecting piece (8) projects particularly into the opening (5) of the pole star ring (1) in the pre-installed state.

14. The electric motor stator (4) according to any one of claims 12 to 13, characterized in that The connecting piece (8) has a break notch.

15. The electric motor stator (4) according to any one of claims 9 to 14, It is characterized in that the yoke ring (2) having a plurality of recesses (10), the plurality of recesses being distributed on the inner circumferential surface for receiving the radial ends (9) of the stator teeth (6).

16. The electric motor stator (4) according to claim 15, Characterized in that, the recesses (10) distributed on the inner circumferential surface of the yoke ring (2) being designed as grooves (19) extending in the axial direction.

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