ELECTRIC MOTOR FOR A WELL PUMP AS WELL AS ASSOCIATED PRODUCTION METHOD

Abstract

Provided are a method and a tool for manufacturing a coil assembly of an electric motor for a deep well vertical turbine pump with a stator assembly that has a stator bore to receive a rotor and slots radially open to the inside which are respectively separated from each other by a stator tooth and in which electrical conductors of coils of the coil assembly lie, forming distributed windings and, at one axial end of the coil assembly, a winding head. The coil assembly is manufactured by shaping and encapsulating the coils within the tool so that the winding head extends only between an inner diameter and an outer diameter that is smaller than the diameter of the stator bore in order to enable axial insertion of the coil assembly into the stator assembly leading with the winding head in which the coils are respectively wound individually, drawn into the tool as wire bundles and encapsulated within it.

Claims

1. A method for manufacturing a coil assembly of an electric motor for a deep well vertical turbine pump having a stator assembly that has a stator bore configured to receive a rotor and slots radially open to inside the stator bore, and separated from each other by respective stator teeth, electrical conductors of coils of the coil assembly lying in the slots, forming distributed windings and, at one axial end of the coil assembly, a winding head, wherein the coil assembly, by shaping and encapsulating of the coils within a tool, is manufactured so that the winding head extends only between an inner diameter and an outer diameter that is smaller than a diameter of the stator bore thereby enabling axial insertion of the coil assembly into the stator assembly leading with the winding head, in which the coils are respectively wound individually, drawn into the tool and encapsulated within it.

2. The method according to claim 1, wherein the tool comprises a winding support having a central guide cylinder and fins, corresponding in number to the stator teeth, arranged at a distance from the central guide cylinder so that there is an annular space between the central guide cylinder and the fins that is open in the axial direction towards an insertion end and configured to receive at least one coil wound in a form of a wire bundle and to form a winding head segment of the coil in the annular space, a respective longitudinal cavity being situated between each two fins adjacent to each other in a circumferential direction in order to form a respective one longitudinal coil segment of the coil, and a. one of the coils is inserted into the annular space from the insertion end so that it extends radially through a first of the longitudinal cavities into the annular space, extends in a curve to a second of the longitudinal cavities and emerges from this again radially, b. the coil is subsequently pushed away from the insertion end towards an opposite second axial end using a heading tool having a shape of a hollow cylinder that is inserted into the annular space and guided on the guide cylinder, where it forms a winding head segment of the coil lying in the winding head, c. a drawing device, comprising a drawing cone is subsequently moved from the second axial end radially along an outside of the fins to the insertion end in order to fold up the coil and press it into the first and second longitudinal cavities until the insertion end is reached, where the coil wraps around the outer circumference of the fins with increasing tension, forming a second winding head segment of the coil that forms part of a second winding head.

3. The method according to claim 2, wherein step a Is initially repeated for several or all the coils and steps b and c are performed subsequently for all the coils together.

4. The method according to claim 3, wherein a sleeve is put axially over the fins from the second axial end to the insertion end, radially delimiting the second winding head in an end position to form a casting mould for it.

5. The method according to claim wherein by locking rods of a locking mechanism having a number of locking rods corresponding to the number of longitudinal cavities are moved into the longitudinal cavities, axially, thereby to close the longitudinal cavities to form a casting mould.

6. The method according to claim 5, wherein at least one locking ring of the locking mechanism radially pushes the locking rods jointly into the longitudinal cavities.

7. The method according to claim 6, wherein the guide cylinder has a rotatable eccentric cone on the insertion end with a shell surface and that is steeper on one side than on a side opposite thereto, and the eccentric cone, for insertion of the coil into the winding support, is rotated to a position where the less steep side of the eccentric cone faces a desired curved course of the coil in the annular space from the first to the second longitudinal cavity.

8. The method according to claim 1, wherein the coil is wound to form wire bundles above the tool using a flyer winder and subsequently dropped into the tool.

9. A tool for manufacturing a coil assembly of distributed windings configured for axial insertion into a stator assembly of an electric motor, the stator assembly having slots radially open to inside the bore, and separated from each other by respective a stator teeth, comprising a winding support having a central guide cylinder and fins, corresponding in number to the stator teeth, arranged at a distance from the central guide cylinder so that there is an annular space between the central guide cylinder and the fins that is open in an axial direction towards an insertion end to receive at least one coil wound in a form of a wire bundle and to form a winding head segment of the coil in the annular space, a respective longitudinal cavity being situated between each two fins adjacent to each other in a circumferential direction in order to form a respective one longitudinal coil segment of the coil.

10. The tool according to claim 9, wherein a heading tool in a form of a hollow cylinder configured to be inserted into the annular space is guided on the guide cylinder, to push the at least one coil to a second axial end opposite the insertion end and to form at the second axial end a first winding head segment of the at least one coil forming part of a first winding head of the coil assembly.

11. The tool according to claim 10, further comprising a drawing device that is movable to the insertion end, sliding radially along the outside of the fins, thereby to fold up the at least one coil.

12. The tool according to claim 11, wherein the drawing device comprises a drawing cone.

13. The tool according to claim 12, further comprising a sleeve configured to be put over the outside of the fins, and slide toward the insertion end to an end position thereby to encompass a second winding head segment of the at least one coil forming part of a second winding head and form a casting mould.

14. The tool according to claim 13, further comprising a locking mechanism having a number of locking rods corresponding to the number of longitudinal cavities and configured to be moved axially into the longitudinal cavities thereby to close the longitudinal cavities to form a casting mould.

15. The tool according to claim 14, wherein the locking mechanism has at least one locking ring configured to jointly push the locking rods radially into the longitudinal cavities.

16. The tool according to claim 15, wherein the guide cylinder has a rotatable eccentric cone on the insertion end with a shell surface that is steeper on one side than on a side opposite thereto.

17. The tool according to claim 16, wherein the drawing device comprises a press ring actuating element configured to slide along the winding support to the insertion end, having a number of sliding dies in an annular arrangement corresponding to the number of longitudinal cavities so that each sliding die projects into a respective one of the longitudinal cavities thereby to press the at least one coil radially into the first and second longitudinal cavities.

18. The tool according to claim 17, wherein each sliding die is supported on a shock resistant block relative to which the sliding die it is radially moveable, the sliding dies being configured to be pushed into the shock resistant blocks against a restoring force.

Description

LIST OF FIGURES

[0068] FIG. 1: Cross-section of a stator assembly of an electric motor according to the state of the art

[0069] FIG. 1a: Illustration of the assignment of the slots of the stator assembly to the phases

[0070] FIG. 1b: Schematic view of the electric motor in an exploded view

[0071] FIG. 1c: Schematic view of a coil winding pattern according to the present invention

[0072] FIG. 2: Perspective view of a two-layer coil assembly made of encapsulated single coils with a view of the shaped first winding head

[0073] FIG. 3a-3c: Various views of a single coil of the coil assembly according to FIG. 2

[0074] FIG. 4: Perspective view of another two-layer coil assembly made of encapsulated single coils

[0075] FIG. 5a-5b: Two different views of a single coil of the coil assembly according to FIG. 4.

[0076] FIG. 6a-6b: Snapshots during the joining of single coils according to FIG. 5a, 5b to make the coil assembly according to FIG. 4

[0077] FIG. 7a-7d: Snapshots during the axial joining of the stator assembly and coil assembly according to FIG. 4

[0078] FIG. 8a-8c: Various perspective views of a one-layer coil assembly made of encapsulated single coils according to another embodiment

[0079] FIG. 9a-9c: A tool for drawing in and encapsulating coils in a radial cross-section

[0080] (FIG. 9a), an axial cross-section (FIG. 9b) along the section boundary A-A according to FIG. 9a and in an exploded view (FIG. 9c)

[0081] FIG. 10a: View of a test tool according to FIG. 9a-c with coils drawn in

[0082] FIG. 10b: View of the test tool according to FIG. 9a-c with the first sleeve in place

[0083] FIG. 11a-1b: Views of the coil assembly as a cast body before (FIG. 11a) and after axially sliding on the stator (FIG. 11b)

[0084] FIG. 11c-11d: Views of the cast body according to FIG. 11a with view of the radially inner first winding head (FIG. 11c) and radially outer second winding head (FIG. 11d)

[0085] FIG. 12a-12f: Various snapshots of a tool during execution of the method according to the present invention for manufacturing the stator assembly by drawing in and folding over the coils

[0086] FIG. 13a-13b: Longitudinal sections through the tool for drawing in and folding over the coils at the point in time shown in FIG. 12d (FIG. 13a) and the point in time shown in FIG. 12f (FIG. 13b)

[0087] FIG. 13c: Perspective view of the press ring actuating element from FIG. 12c FIG. 13d: Individual depiction of a guiding and folding element arrangement of the press ring actuating element from FIG. 12c

[0088] FIG. 13e: Encapsulated coil assembly manufactured according to the present invention by drawing in and folding over using the tool in FIG. 12c

[0089] FIG. 13f: Top view of the locking mechanism of the tool in FIG. 12c

[0090] FIG. 13g: Top view of the tool in FIG. 12c with three coils of a phase

[0091] FIG. 14a-14c: Tool for needle winding and encapsulating the coils of a single phase in a first (FIG. 14a) and second (FIG. 14b) perspective view and in a top view (FIG. 14c)

[0092] FIG. 14d-14e: Enlarged views of the axial ends of the tool according to FIG. 14a-14c

[0093] FIG. 15a: Perspective view of the tool for needle winding and encapsulating the coils with insulated longitudinal cavities

[0094] FIG. 15b-15c: Views of the tool according to FIG. 15a with a view of the interconnected second winding head with a first coil drawn in (FIG. 15b) and two coils drawn in (FIG. 15c).

[0095] Embodiments of the invention for the composition of an electric motor for a deep well vertical turbine pump with a coil assembly 5 according to the present invention are described below.

[0096] The electric motor has a stator made of a mechanical stator assembly 1 and an electric coil assembly 5. The stator assembly 1 has a stator bore 9 with a diameter db to receive a rotor 13 mounted on a motor shaft 14 and slots 4 that are open radially to the inside, more precisely towards the stator bore 9, delimited in the circumferential direction on both sides by respectively one stator tooth 3, so that the stator teeth 3 and the stator slots 4 alternate along the inner circumference of the stator assembly 1. One such stator assembly 1 is shown in FIG. 1 and is commonly known. It consists of a number of plates insulated against each other in the axial direction. The stator teeth 3 transition to a stator ring 2. The stator teeth 3 can be of one piece with the stator ring 2 or attached to it, for example, with positive locking such as a dovetail joint. Merely by way of example, the stator assembly 1 in FIG. 1 has eighteen slots 4; however, the number of slots 4 may be higher or lower.

[0097] For the composition of the electric motor as an induction motor, in the simplest case a three-phase motor supplied by three phases U, V, W, the electric motor has a coil assembly 5 with coils 6 made of electrical conductors 11 formed by what are called distributed windings. In a distributed winding, the corresponding coil 6 of a phase U, respectively its electrical conductor 11, extends within a first slot 4a and a second slot 4b, separated from each other by several stator teeth 3, so that additional slots 3 lie between the first and second slots 4a, 4b in which the coils 6 of other phases V, W are arranged. In case of a two-pole electric motor, the first slot 4a and second slot 4b lie opposite each in the simplest case or are at least arranged within opposite angle segments ?1, ?2 of the stator circumference assigned to the same phase U, V, W; see FIG. 1a. In case of a four-pole electric motor, these angle segments are offset relative to each other by 90?.

[0098] FIG. 1a shows the assignment of the coils 6 to the phases U, V, W and slots for a two-pole motor. A number X/2 of coils 6 are arranged in the X slots 4, i.e. there are nine coils 6 in the present example with X=18 slots. Respectively three of these coils are assigned to a phase U, V, W, connected in parallel and thus forming a group. The groups are electrically interconnected, for example, in a star or delta formation. Each group or phase U, V, W is distributed over two opposite angle segments ?1, ?2.

[0099] The stator assembly 1 has a first axial end and a second axial end. It can have a length between 30 cm and 1.50 m. In the embodiments shown here, the coils 6 respectively form a winding head 7, 8 on the two axial ends of the stator assembly 1 respectively the coil assembly 5 in order to transition from the first slot 4a to the second slot 4b. Thus a winding head 7, 8 is formed by the coil segments 6c, 6d of different coils 6 at an axial end of the coil assembly 5 lying against each other, or more precisely lying over each other axially at least in part.

[0100] The central idea according to the present invention is to form the coil assembly 5 from encapsulated single coils or as a cast body with coils embedded in it, however in a manner independent of the stator assembly 1 as opposed to the state of the art. Thus the coil assembly, i.e. the electrical part of the stator, is manufactured outside the stator assembly. Subsequently the coil assembly 5 is axially inserted into the slots 4 of the stator assembly 1. In order to accomplish this, the intent according to the present invention is for a first of the two winding heads 7, also called the shaped winding head 7 in the following, to extend only between an inner diameter di and an outer diameter d.sub.a, in which the outer diameter d.sub.a is smaller than the diameter D.sub.b of the stator bore 9. Thus the shaped winding head 7 is offset radially to the inside towards the motor axis 10 relative to the stator teeth 3, creating the clearance required to slide the stator teeth 3 between the encapsulated coils 6 during axial joining, as illustrated in FIG. 1b and described in more detail below.

[0101] Accordingly, a method for manufacturing an electric motor comprises the steps: [0102] providing a stator assembly 1 that has a stator bore 9 to hold a rotor and slots 4 that are radially open to the inside, respectively separated from each other by a stator tooth 3, [0103] manufacturing a coil assembly 5 of encapsulated coils 6 or by encapsulating coils made by winding round wire (winding wire) electrical conductors 11 so that the coils 6 form distributed windings and, at one axial end of the coil assembly 5, a winding head 7 that extends only between an inner diameter di and an outer diameter d.sub.a, in which the outer diameter d.sub.a is smaller than the diameter d.sub.b of the stator bore 9, and [0104] axially inserting the coil assembly 5 into the stator assembly 1, leading with the winding head 7, so that the coils 6 are positioned to lie in the slots 4.

[0105] A coil 6 is made of a winding wire continuously wound N times. Thus each coil 6 is a wire bundle consisting of N windings, for instance 50 windings, so that N single wires form the coil 6 viewed in cross-section but are actually segments of the continuous winding wire. The single wires, respectively wire segments, are the electrical conductors of the coil 6. The winding wire is usually a copper round wire coated with an insulating varnish, with a diameter between 0.6 mm and 2 mm.

[0106] Four different methods for manufacturing the coil assembly 5 as a cast body are described below, in which the coil assemblies 5 themselves also differ from each other with regard to the winding heads 7, 8. The third method, hereinafter referred to as drawing in/folding technique, including the tool shown in FIGS. 12a-f and 13a-g, is the object of the claims.

[0107] Encapsulated Single Coils

[0108] According to a first method, the coil assembly 5 is made of individually encapsulated coils 6 that are subsequently nested inside each other to form the coil assembly 5.

[0109] FIG. 2 shows a section of a coil assembly 5 produced in this manner with a view of the first winding head 7, also called the shaped winding head 7 in the present description. Here the coil assembly 5 comprises 18 coils 6 so that each coil 6 lies in two slots 4 but each slot 4 holds two coils 6, lying in an upper winding and a lower winding when viewed radially. In other words, the coil assembly has a two-layer structure. A coil 6 of this coil assembly is shown in various views in FIG. 3a through 3c. The coils 6 are all formed the same in this embodiment.

[0110] Each coil essentially consists of four coil segments, namely a first and second longitudinal coil segment 6a and a first and second winding head segment 6c, 6d. The two longitudinal coil segments 6a, 6b run parallel and lie radially opposite each other. The two winding head segments 6c, 6d lie axially opposite each other.

[0111] The first longitudinal coil segment 6a extends within the first slot 4a axially from the second winding head 8 to the first winding head 7, while the second longitudinal coil segment 6b extends within the second slot 4b axially from the first winding head 7 back to the second winding head 8. However, the two longitudinal coil segments 6a, 6b lie on different circumferences in reference to the motor axis 10, since the first longitudinal coil segment 6a forms the lower winding in the first slot 4a and the second longitudinal coil segment 6b forms the upper winding in the second slot 4b and therefore lies farther out radially than the first longitudinal coil segment 6a.

[0112] The first winding head segment 6c is part of the first winding head 7 and connects the end of the first longitudinal coil segment 6a of the coil 6 emerging from the first slot 4a with the end of the second longitudinal coil segment 6b entering the second slot 4b. Correspondingly the second winding head segment 6d is part of the second winding head 8 and connects the end of the second longitudinal coil segment 6b of the coil 6 emerging from the second slot 4b with the end of the first longitudinal coil segment 6b entering the first slot 4a.

[0113] The shape of the first winding head segment 6c is significant here; it can be seen in FIG. 3a-3c and is carried out in the form of an offset end winding. It consists of five segments that transition to each other, comprising a first S-shaped segment 6ca, which connects to the first longitudinal coil segment 6a, a first curved segment 6cb, a central U-shaped segment 6cc, a second curved segment 6cd and a second S-shaped segment 6ce that connects to the second longitudinal coil segment 6b.

[0114] The first S-shaped segment 6ca turns the path of the coil coming from the axial direction of the first longitudinal coil segment 6a radially inward, so that the coil 6 is brought out of alignment with the corresponding stator slot 4, or viewed differently, projects radially over the stator teeth 3 flanking the slot. In this embodiment, the path is subsequently changed again from the radial direction back to the axial direction, but on a circumference with a diameter d.sub.a that is smaller than the diameter d.sub.b of the stator bore 9.

[0115] The first curved segment 6cb connecting to the first S-shaped segment 6ca extends along an arc in the circumferential direction around the motor axis 10, in which it also rises in the axial direction away from the stator body 1, creating space for the winding head segments 6c of the other coils 6. The U-shaped segment 6cc with its legs extending axially away from the stator body 1 connects the two curved segments 6cb, 6cd approximately in the middle section of the winding head segment 6c. Here the leg connecting to the first curved segment 6cb lies radially on the outside and the second leg connecting to the second curved segment 6cd lies radially further inward in reference to the motor axis 10; see FIGS. 3b and 3c. Thus the U-shaped segment 6cc lies in an axial plane intersecting the motor axis 10.

[0116] The second curved segment 6cd and the second S-shaped segment 6ce are essentially symmetrical counterparts of the first curved segment 6cb and first S-shaped segment 6ca. However, the second curved segment 6cd extends along an arc around the motor axis 10 with a smaller diameter or radius than the arc of the first curved segment 6cb. Furthermore, the second curved segment 6cd ends axially in the direction of the stator assembly 1, offset relative to the first curved segment 6cb; see FIG. 3b.

[0117] The second winding head segment 6d consists of three segments transitioning to each other, comprising a first curved segment 6da that connects to the first longitudinal coil segment 6a, a central U-shaped segment 6db and a second curved segment 6dc that connects to the second longitudinal coil segment 6b. Thus the second winding head segment is also carried out in the form of an offset end winding. Compared to the first winding head segment 6c, the second winding head segment 6d omits changing the path of the coil radially inward, so that the second winding head segment 6d, or more precisely the curved segments 6da and 6dc, lies/lie axially in front of the stator teeth 3. Thus the U-shaped segment 6db lies radially farther out, so that the inside diameter of the second winding head 8 is larger than the outer diameter of the rotor 13, allowing it to pass by the second winding head 8 during axial joining.

[0118] All coils 6 are shaped identically so that the same forming and casting tool can be used, and so that no special sequence of the coils needs to be considered while assembling the single coils into the coil assembly.

[0119] After winding the coil, the resulting wire bundle is wrapped with an insulating material and shaped as shown in FIGS. 3a, 3b and 3c, notably bent. Alternatively the wire can also be shaped first and subsequently wrapped with the insulating material. In this case a binding, tape, cord or spiral coiled tube can be used as the insulating material, in which the insulating material is wrapped around the wire bundle in a spiral. According to another version, the coil 6 can also be wound directly in the required shape, eliminating the need for a separate shaping step.

[0120] The wound wire bundle wrapped with the insulating material is subsequently placed into a casting mould, where it is encapsulated with a sealant. The insulating material ensures that the coil 6 is covered by a sufficient thickness of the sealant on all sides since it serves as a spacer element to the casting mould. A casting resin, for example, can be used as the sealant.

[0121] As an alternative to wrapping the wire bundle with the insulating material as described above, the casting mould can be lined with such an insulating material, for example, in the form of an insulating paper. The wire bundle can be placed on the paper, which is folded over the wire bundle so that it fully encloses the wire bundle.

[0122] According to a different manufacturing method, it is also possible to simultaneously use the casting mould to produce the required shape of the coil 6. Thus shaping the wire bundle is realised directly through insertion and adaptation to the casting mould. Furthermore, it is possible for winding or laying the windings of the winding wire to take place directly in the casting mould, eliminating a separate shaping step.

[0123] FIG. 4 shows an embodiment of a coil assembly 5 as an alternative to FIG. 2. Here the coil assembly 5 also has a two-layer structure and comprises 18 coils, so that two coils 6 lie in each slot 4 in the form of an upper winding and a lower winding.

[0124] The shape of the single coils 6 in this alternative embodiment is shown in FIGS. 5a and 5b. It differs from the first version in FIGS. 2 and 3a-3c to the effect that, on the part of the first winding head 7, a U-shaped segment lies radially on the outside, so that the first S-shaped segment 6ca on the part of the winding head 7 of the first version can be omitted. Here the coil assembly 5 has a torpedo-like overall shape. Once again the coil 6 essentially consists of four coil segments, namely a first and second longitudinal coil segment 6a and a first and second winding head segment 6c, 6d. Only the differences of the second version compared to first version are pointed out in the following.

[0125] The first winding head segment 6c consists of four segments transitioning to each other, comprising a straight segment 6a that forms an extension of the first longitudinal coil segment 6a, a U-shaped segment 6ca that connects to the straight segment 6a, a curved segment 6cbr and an S-shaped segment 6ccr that connects to the second longitudinal coil segment 6b; see FIG. 5a, 5b. Due to the straight segment 6a, the U-shaped segment 6ca projects axially beyond the S-shaped segment 6ccr. The straight segment 6a transitions to a leg of the U-shaped segment 6ca, whose other leg lies radially further inward so that the U-shaped segment 6ca lies in an axial plane encompassing the motor axis 10. The second leg of the U-shaped segment 6ca turns the path of the coil back in the axial direction towards the stator assembly 1 and then transitions to the curved segment 6cbr, which extends in the circumferential direction along an arc, overcoming the axial offset between the U-shaped segment 6ca and the S-shaped segment 6ccr. Thus the curved segment 6cbr also takes a helical path here. The arc lies on a diameter d.sub.a that is smaller than the diameter d.sub.b of the stator bore 9. Thus the curved segment 6cbr is not aligned with any stator slots 4 or stator teeth 3, ensuring that the coil assembly 5 can be joined axially relative to the stator assembly 1. Furthermore, the curved segment 6cbr therefore ends at a radial distance from the second longitudinal coil segment 6b. This distance is bridged by the S-shaped segment 6ccr.

[0126] The shape of the second winding head segment 6d is essentially identical to the first embodiment and consists of a first curved segment 6dar, a U-shaped segment 6dbr and a second curved segment 6dcr, in which the U-shaped segment 6dbr lies approximately in the centre between the curved segments 6dar, 6dcr and extends through the motor axis 10 within an axial plane with its legs. This axial plane is offset by approximately 90? relative to the axial plane in which the U-shaped segment 6car of the first winding head segment 6c extends. The first curved segment 6dar extends along a first arc and the second curved segment 6dcr extends along a second arc that runs radially farther inward compared to the first arc.

[0127] FIGS. 6a and 6b show two snapshots of the arrangement of coils 6 to form the coil assembly 5 by nesting the single coils 6 inside each other. Two coils 6 lie next to each other in FIG. 6a and six coils 6 lie next to each other in FIG. 6b. It is clear that the curved segments 6cbr of the coils 6 lie axially above each other, or more precisely lie against each other axially.

[0128] FIG. 7a through 7d illustrate the joining process of the coil assembly 5 relative to the stator assembly 1, in which the coil assembly 5 is inserted axially into the stator assembly 1 in the direction of the arrow A in FIG. 7a, leading with the first winding head 7. In FIG. 7b the first winding head 7b already slightly protrudes axially from the stator assembly 1. FIG. 7b shows how the stator teeth 3 engage in the spaces between adjacent coils 6 of the stator assembly 5. In FIG. 7c, the stator assembly 1 is positioned almost in its final position relative to the coil assembly 5. The end position is reached in FIG. 7d. FIGS. 7c and 7d show that the first winding head 7 has a considerable axial length.

[0129] A third embodiment of a coil assembly 5 with individually encapsulated coils 6 is illustrated in FIG. 8a through 8c. Here the coil assembly 5 comprises nine coils 6, so that each coil 6 lies in two slots 4 and exactly one coil 6 lies in each slot 4. Thus the coil assembly 5 has one layer. In this third embodiment, the coils 6 are all different from each other, having different axial lengths, and the second winding head 7 is asymmetrical.

[0130] With each of the coils 6, the first winding head segment 6c is formed by three segments that transition to each other, namely a first radial segment 6ca, a curved segment 6cb and a second radial segment 6cc. The first radial segment 6ca connects to the first longitudinal coil segment 6a and turns the path of the coil, coming from the axial direction, radially inward towards the motor axis 10 and subsequently in the circumferential direction. Connected to the first radial segment 6ca is the curved segment 6cb, extending along an arc with a diameter d.sub.a that is smaller than the diameter d.sub.b of the stator bore 9. The curved segment 6cb differs from the curved segments 6cb, 6cd, 6db of versions 1 and 2 in that its path is not helical, i.e. it does not extend in the axial direction but remains within the same radial plane. This ultimately results in the different axial lengths of the coils 6. The second radial segment 6ca connects to the curved segment 6cb and turns the path of the coil, coming from the circumferential direction, to the radial direction and then to the axial direction before transitioning to the second longitudinal coil segment 6b.

[0131] In the second winding head 8 of the third version, the second winding head segments 6d of the coils 6 are also formed by three segments 6da, 6db, 6dc, namely a first curved segment 6da, a transition segment 6db and a second curved segment 6dc, in which the transition segment 6db lies between the first and second curved segments 6da, 6dc. The first curved segment 6da connects to the first longitudinal coil segment 6a and extends helically along an arc on a first circumference around the motor axis 10 to the transition segment 6db, which forms a flat transition to a smaller diameter lying radially farther inward on a circumference around the motor axis 10. Along an arc on this second circumference, the second curved segment 6dc extends helically or axially back in the direction of the stator assembly 1 and connects to the second longitudinal coil segment 6b; see FIG. 8c.

[0132] While the coil shapes differ between the two illustrated versions, the method for manufacturing the wound and individually encapsulated coils is identical; therefore, please refer to the explanations of the first version in this regard.

[0133] Drawing Technique

[0134] A second method proposes winding the coils 6 individually, i.e. laying the N windings and inserting the resulting wire bundles into a drawing tool. Through this insertion as such, the wire bundles are brought into a shape that approximates the final shape of the coil 6. Then the wire bundle can be brought into the final shape by means of the heading tool in the drawing tool. This can be done sequentially for each single coil, for a coil groupe.g. for all coils belonging to the same phaseor even for all coils 6 simultaneously.

[0135] A suitable drawing and casting tool 20 is shown in FIG. 9a through 9c. FIG. 9a through 9c show the drawing and casting tool 20 in a top view (FIG. 9a), a section (FIG. 9b) along the section boundary A-A according to FIG. 9a and in an exploded view (FIG. 9c).

[0136] The drawing and casting tool 20, referred to simply as the tool 20 in the following, comprises an oblong winding support 21 as the central element with a front axial end 35 and a rear axial end 36. The winding support 21 consists of a front winding support segment 22 and a rear winding support segment 23, respectively formed by a circular cylinder. The front winding support segment 22 has a smaller diameter than the rear winding support segment 23, so that the front winding support segment 22 is offset relative to the rear winding support segment 23, forming an annular space to hold the first winding head 7. There is a seamless transition 46 between the two segments 22, 23 of the winding support 21. While the front and rear winding support segments 22, 23 are in one piece in the illustrated embodiment, they can be separate components attached to each other in a different embodiment.

[0137] At the front axial end 35, the winding support 21 has a cone 24 in the form of a taper. This facilitates drawing the coils 6 into the tool 20 and shaping them in the area of the first winding head 7. Alternatively the cone 24 can be a separate component attached to the front winding support segment 22.

[0138] The rear winding support segment 23 has a pin 40 at its axial end formed by an offset of the rear winding support segment 23. Thus the pin 40 is in one piece with the rear winding support segment 23. However, it could also be a separate component mounted on the rear winding support segment 23.

[0139] As shown in FIG. 9c, the outer circumference of the rear winding support segment 23 has longitudinal slots 39 extending axially and parallel to the tool axis 44. A fin 29 lies in each of these longitudinal slots 39 with a positive fit; the fins as a whole protrude from the winding support 21 in a star shape. Overall the tool 20 has eighteen slots 39 for eighteen corresponding fins 29. The fins 29 extend to the axial end of the cone 24. They have a rectangular cross-section along their entire axial length. Their narrow longitudinal side is screwed to the rear winding support segment 23. This is done using screws inserted into corresponding bore holes 33 in the fins 29. The fins 29 have additional bore holes 34 at various locations along their length, extending through the fins 29 and having an internal thread. They are intended for the installation of a corresponding shoulder screw. When this is screwed in to the maximum extent, it first contacts the winding support 21. Continuing to screw in the shoulder screw causes the corresponding fin to be pushed off the winding support 21. This helps release the fins from the winding support 21 when they are embedded in the cast body.

[0140] There is a longitudinal cavity 28 respectively between two fins 29 adjacent to each other in the circumferential direction, which serves to hold a coil 6, or more precisely a longitudinal coil segment 6a, 6b of a coil. The fins 29 of the tool 20 correspond to the stator teeth 3 of the stator assembly 1, in which the longitudinal cavities 28 correspond to the stator slots 4.

[0141] The fins 29 extend beyond the rear winding support segment 23 so that they lie at a radial distance from the front winding support segment 22, forming the aforementioned annular space. The axial face ends 37 of the fins 29 have a radial inner flat area 38 angled relative to the cone 24, forming a funnel-shaped insertion opening that also facilitates drawing the coils 6 into the tool 20.

[0142] The tool 20 also comprises three dies 25, 26, 27 that are moveable radially relative to the winding support 21 and shape a coil 6 drawn into the tool 20 by axially exerting a compressive force. A first die 25 and a second die 26 jointly form a die formation to shape the first winding head 7, pushing the coils 6 in the tool 20 axially downward in the direction of the rear winding support segment 23. The two dies 25, 26 are axially guided on the front winding support segment 22 for this purpose.

[0143] The first die 25 consists of a ring 42 mounted on the front winding support segment 22, with radially projecting teeth 43 integrated on its outer circumference that also extend in the axial direction beyond the ring 42 to the rear winding support segment 23. Two teeth 43 adjacent to each other in the circumferential direction respectively define a slot-like space in which one of the fins 29 lies with a positive fit according to the present invention. Correspondingly each of the teeth 43 extends with a positive fit into one of the longitudinal cavities 28 formed between two fins 29 adjacent to each other in the circumferential direction. Thus the first die 25 encompasses the fins 29 with a positive fit. Viewed in cross-section, the teeth are trapezoidal and their radially outer width is greater in the circumferential direction than their radially inner width.

[0144] The second die 26 is a sleeve in the form of a circular cylinder that is mounted on the front winding support segment 22. Its axial face end is supported on the inside of the ring 42 so that the teeth 43 encompass the outside of the die 26 with a positive fit. A pressing force is thus exerted on the second die 26 by the first die 25 exerting a radial pressing force.

[0145] The third die 27 is also a sleeve in the form of a circular cylinder. It encompasses the fins 29 radially on the outside by contacting the radially outer longitudinal sides of the fins 29 with its inner circumference. The third die 27 can also be omitted. It is not shown in FIG. 9c.

[0146] Completing the drawing tool 20 with a first and second sleeve 30, 31 as well as a cover 32 forms a complete casting tool 20 in which the coils 6 can be encapsulated without pressure.

[0147] The first sleeve 30 is a circular cylinder that, like the die 27, encompasses all fins 29 radially on the outside by contacting the radially outer longitudinal sides of the fins 29 with its inner circumference. Along the inner circumference, the sleeve 30 has axially extending longitudinal slots 41 in which the fins lie with their radially outer longitudinal sides with a positive fit. Thus the first sleeve 30 delimits the longitudinal cavity 28 in the radial direction to the outside and therefore forms part of the casting mould. Consequently, the coils 6 are encapsulated within the first sleeve 30.

[0148] The longitudinal cavities 28 are closed in the axial direction by the cover 32. It forms an annular disk 32 that, in the installed state, lies with its opening 45 on the pin 40 and is moved up to the offset between the pin 40 and the rear winding support segment 23 so that it contacts the axial face end of the rear winding support segment 23. The second sleeve 31 is also a circular cylinder. It encompasses the outer circumference of both the annular disk 32 and the end of the first sleeve 30 facing it axially. The second sleeve 31 delimits the space holding the second winding head 8 to be encapsulated radially to the outside.

[0149] The tool 20 is used as follows:

[0150] The two sleeves 30, 31 and the three dies 25, 26, 27 are initially removed so the tool 20 serves as a drawing tool. The longitudinal cavities 28 are open radially to the outside and towards the front axial end 35.

[0151] A coil is initially wound, forming an annular wire bundle by laying the winding wire in N loops that form the N windings of the coil. Then the wire bundle is insulated with an insulating material, as previously explained for the embodiment with the encapsulated single windings. However, the longitudinal cavities 28 may also be lined with an insulating material, for example, a folded insulating paper, so that insulating the wire bundle outside the tool 20 can be omitted. Then the wire bundle is inserted into the tool 20.

[0152] The wire bundle is drawn in at the front axial end 35 by pressing the wire bundle extending radially on the face end between the first two fins 29, which delimit the first longitudinal cavity 28 that is to receive the coil 6. Then the wire bundle is guided over the front axial end 35 to the second two fins 29, which delimit the second longitudinal cavity 28 that is to receive the coil 6. In case of a two-pole electric motor, the first two fins 29 and the second two fins 29 lie in diametrically opposite angle segments ?1, ?2; see FIG. 1a. In doing so, the wire bundle is moved past the cone 24 and extending radially on the face end, is pressed between the second two fins 29.

[0153] During this process, the remainder of the wire bundle hangs outside in front of the fins 29.

[0154] Subsequently the wire bundle is drawn down in the direction of the rear axial end 36, in which it contacts the cone 24. In doing so, the first and second die 25, 26 are used to press the wire bundle axially into the tool 20 until it contacts the stepped transition 46. Here the second die 26 is guided on the front winding support segment 22. At the stepped transition 46 coming from the first longitudinal cavity 28, the wire bundle radially enters the annular space formed between the fins 29 and the front winding support segment 22, occupied in FIG. 9b by the second die 26, and then extends in a curve within this annular space in a radial plane to the second longitudinal cavity 28, which it enters radially coming out of the annular space. The segment of the wire bundle lying in the annular space corresponds to the first winding head segment 6c in FIG. 3a-3c, 5a, 5b.

[0155] Then the wire bundle is pressed into the first and second longitudinal cavity 28 so that it extends axially within the longitudinal cavities 28 to the rear axial end 36. The segments of the wire bundle lying in the longitudinal cavities 28 correspond to the longitudinal coil segments 6a, 6b in FIG. 3a-3c, 5a, 5b.

[0156] Since the wire bundle forms a closed ring, the segment of the wire bundle forming the second winding head segment 6d in FIG. 3a-3c, 5a, 5b remains radially outside the fins 39 during this step. This stays that way during the remainder of the process as well, so that the second winding head does not lie axially in front of the stator teeth 3, as in versions 1 through 3, but is radially offset relative to it and lies axially in front of the stator ring 2.

[0157] Consequently, the wire bundle emerges radially from the two longitudinal cavities 28 at the rear axial end 36 and then extends in the circumferential direction radially outside in front of the fins from the first to the second longitudinal cavity 28. With the third die 27, the wire bundle or more precisely its second winding head segment lying radially outside the fins 29 can be pushed in the direction of the cover 32 until it contacts the cover 32. Here the third die 27 is guided by the outer longitudinal side of the fins 29. The wire bundle is stretched overall during this pressing step. The second winding head segment lies in a second annular space that is occupied by the third die 27 in FIG. 9b.

[0158] The described method is repeated for all coils/wire bundles.

[0159] As described above, the tool 20 comprises eighteen fins 29 so that eighteen longitudinal cavities 28 can also be formed. Thus the tool 20 is intended for manufacturing a coil assembly 5 for a two-pole motor with three coils 6 per phase U, V, W (see FIG. 1a), so that nine coils have to wound in total and drawn into the tool 20. Naturally the tool 20 can also have a different number of fins 29, respectively cavities 28, in other embodiments.

[0160] In order to draw the three coils 6 per phase into the tool 20, there is a special assignment of the longitudinal cavities 28 to the three coils 6. FIG. 1c illustrates this assignment. Insofar the method uses a special winding concept.

[0161] As illustrated in FIG. 1c, the coils of each phase U, V, W are distributed over two opposite angle segments ?1, ?2, ?1, ?2, and ?1, ?2 of the inner circumference of the stator, in which each angle segment comprises three adjacent slots 4 to hold the three coils of a phase U, V, W. The first phase U is examined in the following, comprising a first coil 6.1, a second coil 6.2 and a third coil 6.3, whose first longitudinal coil segments 6a lie in the three adjacent slots 4.1, 4.2 and 4.3 of the first angle segment ?1, and whose second longitudinal coil segments 6b lie in the three adjacent slots 4.10, 4.11 and 4.12 of the second angle segment ?2.

[0162] To obtain symmetrical winding heads 7, 8, the intent is for a coil 6 to respectively lie in those two slots 4 of opposite angle segments that are nearest each other viewed in the circumferential direction, i.e. that have the shortest distance between them on the face end of the stator assembly 1 in the circumferential direction.

[0163] In order to realise this, the intent is for the third coil 6.3, which lies in the far right slot 4.3 of the first angle range ?1 in order to get from the second winding head 8 to the first winding head 7, to also use the far right slot 4.10 of the second angle range ?2 to get from the first winding head 7 back to the second winding head 8. Correspondingly the first coil 6.1, which lies in the far left slot 4.1 of the first angle range ?1 to get from the second winding head 8 to the first winding head 7, also uses the far left slot 4.12 of the second angle range ?2 to get from the first winding head 7 back to the second winding head 8. Thus the first and third coils 6.1, 6.3 do not use any slots 4 that are opposite each other. This is however necessary for the second coil 6.2 because it lies in the middle between the first and third coils 6.1, 6.3. To obtain a symmetrical winding head 7, 8, the wire bundle of the second coil 6.2 is divided in half, forming two partial bundles 6.2a, 6.2b that are routed in circumferential directions opposite to each other.

[0164] In reference to the drawing tool 20, whose longitudinal cavities 28 correspond to the slots 4 of the stator assembly 1, this means that a first coil 6 of a phase that is inserted into a first longitudinal cavity 28 is not routed to the diametrically opposite longitudinal cavity 28, but to the one that lies two longitudinal cavities 28 closer in the anticlockwise direction. Subsequently the second longitudinal cavity 28 that is adjacent to the first longitudinal cavity 28 in the clockwise direction is left empty and the third coil of the phase is drawn into the third longitudinal cavity 28 adjacent to that; this too is not routed to the diametrically opposite longitudinal cavity 28 but to the one that lies two longitudinal cavities 28 closer in the clockwise direction. Then the middle, second coil 6 is drawn in with its first two and second two partial bundles 6.2a, 6.2b. The partial bundles 6.2a, 6.2b are laid around the cone 24 or the front winding support segment 22 in opposite circumferential directions to each other on the part of the first winding head 7. Furthermore, the partial bundles 6.2a, 6.2b are laid around the fins 29 in circumferential directions opposite to each other on the part of the second winding head 7.

[0165] Contrary to the procedure that has been described, the second coil of a phase can also be drawn into the tool 20 first, followed by drawing in the first and third coils.

[0166] FIG. 10a shows the drawing tool 20 with coils 6 made of wire bundles wrapped with insulating material 15 drawn into the longitudinal cavities 28. It clearly shows the first winding head 8 lying radially in front of the fins 29 and the division of the centre, second coil 6.2 into two partial bundles 6.2a, 6.2b realised within that, into which the coil 6.2 branches in the first winding head 8 in order to encompass the fins 29 respectively to the right and left. The two partial bundles 6.2a, 6.2b lie axially above the winding head segments of the first and third coils 6.1 and 6.3, which makes it clear that the second coil 6.2 was drawn into the tool 20 after drawing in the first and third coils 6.1, 6.3.

[0167] Naturally, instead of dividing the second coil 6.2 of a phase in the winding heads 7, 8, two coil sections with N/2 windings can be produced directly as the second coil and drawn into the tool 20. These coil sections with their corresponding longitudinal coil segments 6a, 6b are then inserted into the same longitudinal cavities 28. The longitudinal coil segments 6a, 6b adjacent to each other can be wrapped individually with the insulating material 15 so that two wire bundles lie in the longitudinal cavities 28 of the second coil 6.2, or jointly so that only one wire bundle lies in the longitudinal cavities 28 of the second coil 6.2.

[0168] As previously described as well, the longitudinal cavities can be lined with an insulating material, for example, a folded insulating paper, instead of wrapping the wire bundles with the insulating material 15 outside the tool 20.

[0169] To encapsulate the coils 6, the three dies 25, 26, 27 are removed from the tool 20 and the first and second sleeves 30, 31 are put over the tool. Then the sealant is poured into the tool 20 so that all coils 6 are encapsulated together, forming a monolithic cast body.

[0170] The cast body is demoulded after the sealant has hardened. To do so, the sleeves 30, 31 are first pulled off; the first sleeve 30 is moved in the direction of the front axial end 35 and the second sleeve 31 in the direction of the rear axial end 36 relative to the cast body. Subsequently the fins 29 are released from the winding support 21, notably unscrewed, and removed by pulling them out towards the front axial end 35. Finally, the winding support 21 is pulled out of the cast body axially in the direction of the rear axial end 36.

[0171] Various views of the demoulded cast body are shown in FIG. 11a through 11d. In FIG. 11b, a stator body 1 has been put axially over the cast body for illustrative purposes. The cast body forms the coil assembly 5. It essentially consists of three segments, a first ring cylinder in which the first winding head 8 is encapsulated, a number of rods extending in parallel in which the longitudinal coil segments of the coils 6 are encapsulated, and a second ring cylinder in which the second winding head 7 is encapsulated.

[0172] On one end, the rods project radially to the inside in the form of teeth from the inner surface of the first ring cylinder, see FIG. 11d, and extend axially away from it. On the other end, they transition to the second ring cylinder and project radially away from its outer surface; see FIG. 11c. In other words, the second ring cylinder lies within the space framed by the rods. The clearances between the rods are provided to receive the stator teeth, as illustrated in FIG. 11b by means of the stator assembly 1 that has been put on.

[0173] Drawing/Folding Technique

[0174] According to a third method for manufacturing the coil assembly 5, the coils 6 are folded starting from the first winding head 7 towards the second winding head 8 while drawing them into a corresponding winding support 51. This procedure is called the drawing/folding technique here. The tool 50, 51 that is used is shown in FIGS. 12a-f and 13a-g. FIG. 12a-12f illustrates the state of the tool 50 with the winding support 51 at different points in time.

[0175] FIG. 12a shows the winding support 51 with three coils 6 of a first phase U, namely a first coil 6.1, a second coil 6.2 and a third coil 6.3, whose winding head segments 6c forming the first winding head 7 have already been drawn into the winding support 51. Here the coils 6 are shown as having a rectangular cross-section and being massive, merely for illustrative purposes. However, as with the previous embodiments, these are bendable wire bundles consisting of winding wire, more precisely round wire, laid in a number N of windings.

[0176] The winding support 51 has a central guide cylinder 52 that is exposed at a first axial end 65 that forms an insertion end of the winding support 51 to receive the coils 6. At the opposite second axial end 66, an annular base plate 74 is integrated in one piece with the guide cylinder 52; see FIG. 13b. However, the base plate 74 could also be a separate component. From the base plate 74, a number of parallel fins 59 also rise in the axial direction, arranged equidistant along the periphery of the base plate 74 and partly projecting radially from the base plate 74. This creates a guide for the locking rods 91 that are explained below. There is respectively one longitudinal cavity 58 between two fins 59 adjacent to each other in the circumferential direction, into which a longitudinal segment 6a, 6b of a coil is drawn. Furthermore, there is an annular space 71 between the central guide cylinder 52 and the fins 59 to guide each of the first winding head segments 6c of the coils 6 from a longitudinal cavity 58 along an arc around the guide cylinder 52 to another longitudinal cavity 58, and to enable pushing this first winding head segment 6c within the winding support 51 in the axial direction to the second axial end 66 or in the direction of the base plate 74.

[0177] The guide cylinder 52 has a head in the form of an asymmetrical cone 54 at the first end 65, which serves as a deflecting eccentric and is referred to as the eccentric cone in the following. The eccentric cone 54 has a shell surface that is steeper on one side than on the opposite side. The eccentric cone 54 is connected to a rotatable pin 55 extending through the guide cylinder 52 and projecting from the underside of the base 74. The eccentric cone 54 can be rotated around the central pin 55 to position the less steep shell surface so that it faces towards the curved segment 6cb to be formed on the coil 6 that is to be drawn in. The coil 6 then slides along the less steep side of the eccentric cone 54 down into the annular space 71.

[0178] The annular space 71 is open in the axial direction at the first axial end 65 for insertion of the coils 6.1, 6.2, 6.3. To facilitate insertion, the face ends 67 of the fins 59 are rounded. The fins 59 end at the same level as the guide cylinder 52 so that the eccentric cone 54 projects axially relative to the face ends 67 of the fins 59.

[0179] As shown in FIG. 12a, the first and third coils 6.1, 6.3 lie in the same radial plane and axially above the second coil 6.2, i.e. on the side of the first axial end 65 (insertion end) of the second coil 6.2. Consequently they were inserted into the winding support 51 after the second coil 6.2. FIG. 13g shows the winding support 51 and the coils 6.1, 6.2, 6.3 with their arrangement in a top view. As already explained for the second embodiment, the second coil 6.2 consists of two coil sections 6.2a, 6.2b in order to obtain symmetrical winding heads 7, 8. The two coil sections 6,2a, 6.2b form common longitudinal coil segments 6a, 6b and are thus drawn into the same longitudinal cavities 58.

[0180] The assignment of the longitudinal cavities 58 to the individual coils 6.1, 6.2, 6.3 is as explained in reference to FIG. 1c. Thus only the two longitudinal cavities 58 assigned to the second coil 6.2 lie diametrically opposite each other, while the two longitudinal cavities 58 respectively assigned to the second and third coils 6.1, 6.3, in reference to the second coil 6.2, lie on the same side in the right or left half-space, or put differently, within the same circumferential semi-circle; see FIG. 13g.

[0181] The fins 59 have a rectangular cross-section. Their radial width is larger on the second axial end 66 than on the first axial end 65, in which there is a linear transition 68 opposite the guide cylinder 52 between a first fin segment with the smaller radial width and the second fin segment with the larger radial width. The linear transitions 68 of the fins 59 respectively form part of an inner cone surface that serves as a support for a heading tool 56, which has a corresponding outer cone 57. Due to the different radial widths of the fin segments, the annular space 71 is radially wider in the area of the first fin segments than in the area of the second fin segments.

[0182] In FIG. 12b the aforesaid heading tool 56 has been moved into the winding support 51 in the axial direction of the arrow B, filling the annular space 71, and has pushed the coils 6.1, 6.2, 6.3 to the second axial end 66 or in the direction of the base plate 74. The heading tool 56 is carried out as a hollow cylinder, in which the central guide cylinder 52 extends into its inner cavity 73; see FIG. 13a. The shell surface of the pressing cylinder 56 is formed by flat areas (facets) to fit flush against the radial inner face ends of the fins 59. Given a number n of fins 59, the outside cross-section of the heading tool 56 consequently forms an n-sided polygon.

[0183] The head 69 facing towards the second axial end 66 of the winding support 51 has a smaller outer diameter than the remainder of the heading tool 56, in which there is a conical segment between the head 69 and the aforesaid remainder, forming the aforementioned outer cone 57. FIG. 12b shows that the heading tool 56 contacts the linear transitions 68 of the fins 59 with its outer cone 57 so that these linear transitions 68 form stops for the heading tool 56 and thus define the maximum insertion depth for the heading tool 56, which has been reached in FIG. 12b. Here the coils 6.1, 6.2, 6.3 lie axially in front of the head 69 with their first winding head segments 6c.

[0184] FIG. 12c now shows the tool 50, 51 with the winding support 51 and the fixture 50 for drawing in and folding the coils 6, which is also used for encapsulating them. The fixture 50 is moveable in the axial direction relative to the winding support 51.

[0185] The fixture 50 comprises a drawing device 70, 80 that is configured to fold up the coils 6 and press them into the longitudinal cavities 58. The drawing device has a hyperbolic drawing cone 70 that is pushed axially over the winding support 51 starting from the second axial end 66 in the direction of the arrow C. The drawing cone 70 has a radial collar 75 in the form of an annular disk on which the individual coils 6 rest prior to folding. A hyperbolic segment 76 of the drawing cone 70, see FIG. 13a, connects the collar 75 with a cylindrical segment 77 that encompasses the fins 59 radially on the outside and moves along them. During the axial movement of the drawing cone 70 to the first axial end 65 relative to the winding support 51, the hyperbolic segment 76 progressively folds up the coils 6 so they line up in the axial direction parallel to the winding support 51, whereby the longitudinal coil segments 6a, 6b are automatically pressed into the corresponding longitudinal cavities 58 from which they originally emerged radially starting from the first winding head 7. The folding movement is illustrated in FIG. 12d, for which FIG. 13a shows a cross-sectional view along an axial section through the tool axis 60. The section passes through the first coil 6.1 while the third coil 6.3 is not shown. In these figures the drawing device 70, respectively the insertion cone 70, has already been pushed partly over the winding support 51.

[0186] Note that FIG. 13a shows the sectioned first coil 6.1 near the base plate 74, i.e. much deeper than the heading tool 52 can push the first winding head segment 6c of the first coil 6.1. This is because the coils 6 of the other phases have already been inserted into the winding support 51 as well, but are not shown in FIG. 13a. The first winding head segments 6c of these other coils 6 are between the winding head segment 6c of the first coil 6.1 and the heading tool 52, which has consequently pushed all first winding head segments together ahead of it in the direction of the base plate. According to the present invention, the first winding head segment 6c of the second coil 6.2m lies between the first coil 6.1 and the base plate 74, i.e. under the first coil 6.1; see FIG. 12a, 12b.

[0187] On the side of the insertion cone 70 axially opposite the winding support 51, there is a sleeve 72 that is moved together with the insertion cone 70 on the outside over the winding support 51 toward the first axial end 65 to an end position, where it forms a radial outer delimiter for encapsulating the second winding head 8; see FIGS. 12f and 13b. A ring 88 is attached to the sleeve 72 for sealing and fully encompasses its outer circumference from the underside. It has an inner land for this purpose so that the inner radius of the ring 88 is larger on the side of the sleeve 72 than on the side facing away from it. The land forms a step 89 with which the ring 88 lies against the face end of the sleeve 72.

[0188] Furthermore, the drawing device 70, 80 comprises a press ring actuating element 80 shown by itself in FIG. 13d. It has a number of sliding dies 84 arranged in an annular shape, corresponding to the number of the longitudinal cavities 58, which are pushed onto the winding support 51 following the sleeve 72 so that each sliding die 83 projects into one of the longitudinal cavities 58 in order to press the corresponding longitudinal coil segment 6a, 6b of the respective coil 6 deeper into the corresponding longitudinal cavity 58. All sliding dies 84 collectively form a press ring. FIG. 13a shows that the radial face end of a sliding die 83 lies against the longitudinal coil segment 6a of the coil 6.3 and presses it radially inward. The sliding dies 83 move in this radial position between the fins 59 along the winding support 51 to the second winding head 8 at the first axial end 65.

[0189] In order to perform the aforementioned task, the sliding dies 83 are approximately trapezoidal in their radial cross-section, projecting into a longitudinal cavity 58, essentially form-fitting. The radially outer reverse side of the sliding dies 83 is extended towards the two circumferential sides by respectively one protrusion 83a, 83b so that a sliding die 83 is approximately T-shaped. FIG. 13c also shows that the top edge 83c of the sliding dies 83 facing the drawing cone 70 is rounded. This facilitates sliding along the longitudinal coil segments 6a, 6b as well as moving over coil segments projecting radially from the longitudinal cavity 58 and pushing them radially back into the longitudinal cavity 58.

[0190] Each sliding die 83 is held in a respective shock resistant block 81 by a shaft 82. The shock resistant blocks 81 are mounted on a mounting ring 84 in an annular arrangement so that the sliding dies 83 extend radially to the tool axis 60. The sliding dies 83 are radially moveable relative to the shock resistant blocks 81 and can be pressed into the shock resistant blocks 81 against a restoring force. To this end, the shock resistant blocks 81 can be made of an elastic material or be filled with one, or contain a mechanical energy storage device such as a spring, in which the material or spring in its stress-free state pushes the shaft 82 with sliding die 83 away from itself and is compressed by a radial movement of the sliding die 83 to the outside.

[0191] The press ring actuating element 80, as previously explained, is moved in the direction of the first axial end 65 to the second winding head 8. Here the longitudinal coil segments 6a, 6b necessarily project radially from the longitudinal cavities 58 in order to then be curved to the right or left around the fins 59. Due to the radial projection of the longitudinal coil segments 6a, 6b from the longitudinal cavities 58 toward the second winding head 8, the sliding dies 83 are pushed radially outward into the shock resistant blocks 83 with the progressive axial movement toward the first axial end 65. This in turn facilitates the movement of the press ring actuating element 80 over the sleeve 72.

[0192] As shown in FIG. 12e, the press ring actuating element 80 in the end position of the sleeve 72 is moved farther up relative to the winding support 51, namely to the outside over the sleeve 72. To do so, the sliding dies 83 are also pushed into the shock resistant blocks 81 by the radial thickness of the sleeve 72 so that the press ring actuating element 80 can be moved over the sleeve 72. The drawing device 70, 80, i.e. the drawing cone 70 and the press ring actuating element 80, can be subsequently removed upward.

[0193] FIG. 13d illustrates a guiding and folding element 85 on its own, which has the press ring actuating element 80 below each sliding die 83. The effect of the guiding and folding element 85 is also shown, which is intended for folding an insulation 15 in the form of an insulating paper during the movement of the press ring actuating element 80 around the electrical conductor 11 so that it is fully encased by the insulation 15.

[0194] Here the electrical conductor 11 is shown as rectangular, merely by way of example, although it is a round or oval wire bundle in practice.

[0195] The longitudinal cavities 58 are lined with the insulation 15 prior to the insertion of the coils 6. The insulation 15 has a U-shaped cross-section, in which a right side flank 15a and a left side flank 15b project radially from each of the longitudinal cavities 58.

[0196] A guiding and folding element 85 consists of a back part 85b, here in the form of a right-angled triangle, with a first front end in the movement direction E that has a first folding blade 86b integrated on the right side and a rear end in the movement direction E that has a second folding blade 87c integrated on the left side. Thus the first and second folding blades 86b, 87c on the one hand are at a distance from each other axially, in which the first folding blade 86b leads, and on the other hand arranged opposite each other in reference to a longitudinal cavity 58. Here the first folding blade 86b is intended for folding the right side flank 15a of the insulation 15 over the electrical conductor 11 and the second folding blade 87c is intended for folding the left side flank 15b of the insulation 15 over the electrical conductor 11. The folding blades 86b, 87c essentially project at a right angle from the back part 85b in the direction of the longitudinal cavity 58.

[0197] Each of the folding blades 86b, 87c is defined by a rectangular basic shape with a greater length than width. Both folding blades 86b, 87c extend opposite to the movement direction E with their longitudinal axis or, more simply put, to the rear.

[0198] The first folding blade 86b is twisted by 90? along its longitudinal axis so that its width from a radial alignment with the longitudinal cavity 58 at the proximal end 86bo transitions continuously to a parallel alignment with the longitudinal cavity 58 at the distal end 86bu, and the distal end 86bu simultaneously lies close to the cavity in order to contact the electrical conductor 11 as a tongue. As shown in FIG. 13d, the right side flank 15a of the insulation 15 is guided long the inner side of the first folding blade 86b facing the left side flank 15b and increasingly turned over or folded over the electrical conductor 11 due to the twist of its longitudinal axis during the movement of the guiding and folding element 85 in the direction E.

[0199] The second folding blade 87c is folded by 90? along its diagonal so that a first segment 87co on the right side of the diagonal folding line is positioned radially to the longitudinal cavity 58 and a second segment 87cu on the left side of the folding line lies parallel to the longitudinal cavity 58 and close to it in order to contact the electrical conductor 11 as a tongue. As shown in FIG. 13d, the left side flank 15b of the insulation 15 is guided along the inside of the second folding blade 87c facing the right side flank 15a and turned over or folded over the electrical conductor 11 due to the diagonal fold during the movement of the guiding and folding element 85 in the direction E.

[0200] Since the first folding blade 86b leads, the right side flank 15a of the insulation 15 is folded first, so that the second folding blade 87c folds the left side flank 15b of the insulation 15 over the previously folded first side flank 15a.

[0201] The first folding blade 86b is connected to the front end of the guiding and folding element 85 only on its longitudinal side at its proximal end 86bo, so quasi with a point connection. The guiding and folding element 85 at the same level opposite the first folding blade 86b has a side wall 87b that is integrated with the back part 85b. The left side flank 15b of the insulation 15 is guided along this side wall 87b as well. The second folding blade 87c projects from the side wall 87b with the first segment 87co integrated into the side wall 87c.

[0202] As illustrated in particular by FIGS. 13a and 13c, there is a guiding and folding element 85 of the type described above underneath each sliding die 83. FIG. 13a shows that the sliding dies 83 have an axial extension 85a, 85b on their radially outer reverse side, pointing down or against the intended movement direction E of the drawing device 70, 80. The extension 85a, 85b is of one piece with the respective sliding die 83. The extension 85a, 85b forms the guiding and folding element 85 and consists of a first extension segment 85a, 86a, 87a, axially connected directly to one of the sliding dies 83, and a second extension segment 85b, 86b, 87b connected below that.

[0203] FIG. 13c shows that the first extension segment consists of a back part 85a and two guide walls 86a, 87a that are integrated on the sides of the back part 85a in the circumferential direction and project approximately radially to the fixture axis 60. They ensure that the right and left side flanks 15a, 15b of the insulation 15 stay aligned with the longitudinal cavity 58 and do not project from it. The side flanks 15a, 15b of the insulation 15 are held between the guide walls 86a, 87a.

[0204] The second extension segment 85b, 86b, 87b is formed by the part of the guiding and folding element 85 shown in FIG. 13d, namely by the back part 85b, the first folding blade 86b and the side wall 87b, as well as the second folding blade 87c.

[0205] As shown further in FIG. 12c, the ring 88 with the land, which forms a step 89 in the transition from the side of the ring 88 facing the press ring actuating element 80 with a smaller radial thickness to the side of the ring 88 facing away from the press ring actuating element 80 with a larger radial thickness, lies axially below the press ring actuating element 80.

[0206] The fixture 50 further comprises a locking mechanism 90 that, in the initial state of the method, is also located below the winding support 51 in order to move axially into the winding support 51 from the direction of the second axial end 66 up to an end position, which is shown in FIG. 12e, in order to radially close the longitudinal cavities 58 so the coils 6 can be encapsulated.

[0207] The locking mechanism 90 has a number of locking rods 91 corresponding to the number of longitudinal cavities 58 that are intended for form-fitting insertion into the longitudinal cavities 58. For this purpose, the locking rods 91 are positioned equidistant in an annular arrangement and, on their end opposite the winding support 51, joined together as one piece with a common supporting ring 92. Approximately in the middle in reference to their axial overall length and in the middle of the lower half, the locking rods 91 have respectively one locking ring 93, 94 that pushes the locking rods 91, or more precisely all locking rods simultaneously, radially inward. FIG. 13f shows the upper locking ring 93 in a top view of the locking mechanism 90. The structure of the second locking ring 94 is identical.

[0208] Each of the locking rings 93, 94 is formed by an annular arrangement of track blocks 97 mounted on the radial outer side of the locking rods 91 at the same axial height so that all track blocks 97 lie in the same radial plane. The track blocks 97 on their reverse side facing away from the corresponding locking rod 91 have a track 97a that is bordered by two axially opposite side flanks 97b, 97c; see FIG. 13b. A tensioning belt 96 passing around the locking rods 91 and connecting the track blocks 97 lies in the track 97a, held in position by the side flanks 97b, 97c so it cannot slip out of place.

[0209] A holder 98 is arranged on one of the locking rods 91 respectively at the height of the first and second locking rings 93, 94 for a torque rod 95 that passes through these holders 98 and is held within them so it can rotate. As shown in FIGS. 13b and 13f, each of the holders 98 bears a cylindrical pin 99, on the circumference of which the corresponding tensioning belt 96 is routed tangentially and on which the tensioning belt 96 is attached with one of its ends. The other end of the tensioning belt 96 is routed tangentially to the torque rod 95 and attached to this. By rotating the torque rod 95 in the circumferential direction in which the tensioning belt 96 lies tangentially against the torque rod 95, i.e. in the direction of the arrow E in FIG. 13f, the tensioning belt 96 is increasingly wrapped around the torque rod 95 so that its length decreases and thus the diameter of the tensioning belt 93, 94 decreases. This in turn causes the locking rods 91 to be moved radially inward towards the tool axis 60 to close the longitudinal cavities 58.

[0210] In the state where the locking mechanism 90 has been axially inserted into the winding support 51, as shown in FIG. 12e, the aforementioned rotation of the torque rod 95 and thus the tensioning of the locking rings 93, 94 is realised so that the locking rods 91 are pressed between the fins 59, thereby closing the longitudinal cavities 58 of the winding support 51 in the radial direction.

[0211] Simultaneously the sleeve 72 on the first axial end 65 lies at the level of the second winding head 8 and delimits it radially to the outside. The drawing device 70, 80 or more precisely the drawing cone 70 and the press ring actuating element 80 can be removed in the end position or moved axially to a non-interfering distance from the winding support 51, resulting in the state shown in FIG. 12f. For simplicity, the second winding head 8 is shown here only as a massive ring, even though it consists of single wire bundles lying axially above each other with numerous clearances between them and to the sleeve 72. These are filled when the coils 6 are encapsulated.

[0212] The sealant is poured without pressure from the first axial end 65, i.e. the end of the second winding head 8. It flows through the clearances and cavities between the wire bundles of the coils 6 in the second winding head 8 and the longitudinal cavities 58 to the first winding head 7, fully encapsulating all coils along with the winding heads 7, 8. The encapsulated coil body 5 is shown in FIG. 13e.

[0213] Needle Winding Technique

[0214] Another method for manufacturing the coil body 5 consists of winding the single coils with a needle winding device within a winding support and then encapsulating them inside this winding support. A tool 20 forming this winding support is shown in FIG. 14a-14e. FIG. 15a-15c shows the tool 20 in practice.

[0215] The layout of the tool 20 essentially corresponds to that of the drawing and casting tool 20 in FIG. 9a through 9c. Therefore, please refer to the explanations for those figures. Only the differences are described below. Unlike the drawing tool 20, the winding tool 20 does not have the first, second and third dies 25, 26, 27 due to the method. The winding tool 20 also comprises a winding support 21 with a front winding support segment 22 and a rear winding support segment 23, in which the front winding support segment 22 has a smaller diameter than the rear winding support segment 23, so that the front winding support segment 22 is offset relative to the rear winding support segment 23, forming an annular space to receive the first winding head 7. The front axial end 35 of the winding support 21 has a cone 24 and the rear axial end 36 has a pin 40. A mounting sleeve 47 is attached form-fitting on the pin 40 and the second winding head 8 is wound on that. The mounting sleeve 47 projects radially relative to the rear winding support segment 23.

[0216] The rear winding support segment 23 has parallel longitudinal slots 39 distributed equidistant over the circumference to receive fins 29, of which only those required for winding a single phase are mounted in FIG. 14a-14e. In greater detail, eight fins 29 are mounted here in groups of four fins 29 each, opposite each other in angle segments ?1, ?2. As before, there is a longitudinal cavity 28 respectively between two fins 29 adjacent to each other in the circumferential direction. The fins 29 extend toward the front axial end 35 beyond the rear winding support segment 23 so that they lie at a distance from the front winding support segment 22, forming the aforementioned annular space.

[0217] In contrast to the illustrated drawing tool 20, the fins 29 have a T-shaped cross-section so that the slot opening is narrower than the slot width on the inside of the longitudinal cavities 28. This reduces the risk of the winding wire emerging from a longitudinal cavity 28. The longitudinal edges of the fins 29 that face each other have been bevelled, so that a wire that may have been wound inaccurately nevertheless slides into the longitudinal cavity 28 along the flat area tilted toward the longitudinal cavity. All other edges of the fins 29 on their face end opposite the cone 24 are bevelled as well.

[0218] On the part of the rear axial end 36, a retaining element 48 is mounted radially outside on each fin 29, notably screwed. Each retaining element 48 comprises a finger 49 that extends in the axial direction and lies radially farther out than the corresponding fin 29.

[0219] Winding the winding support 21 is carried out with a needle winding device that continuously feeds the winding wire under tension, in which the needle winding device and the winding support 21 are moveable relative to each other, bidirectionally in at least 3 spatial directions, namely axial, radial and in the circumferential direction.

[0220] The longitudinal cavities 28 are lined with an insulating paper 15 prior to winding. As shown in FIG. 15a, this insulating paper 15 is folded in a U shape and projects at the rear axial end 36 of the longitudinal cavities 28 to prevent lateral contact of the winding wire with the fins 29. The T shape of the fins 29 keeps the insulating paper 15, which contacts the protrusions of the T-fins 29 projecting in the circumferential direction with its longitudinal sides, from sliding out. FIG. 15a also shows that the mounting sleeve 47 is sheathed with an insulating material 15.

[0221] Winding a coil 6 is now carried out in the tool 20 in a manner that is known as such, for example, by repeatedly [0222] a) drawing in the winding wire through an axial linear movement of the needle winding device from the rear axial end 36 in the longitudinal direction of the winding support 21 parallel to the fixture axis 44 to the front axial end 35 into a first longitudinal cavity 28 that is radially open to the outside, from which the wire emerges axially at the end of the first axial movement, [0223] b) rotating the winding support 21 around the axis 44 with a first rotational movement until the needle winding device is aligned with a certain second longitudinal cavity, into which the winding wire is to be drawn, [0224] c) drawing the winding wire, with a second linear movement of the needle winding device, back from the front axial end 35 in the longitudinal direction of the winding support 21 parallel to the fixture axis 44 to the rear axial end 35 into the second longitudinal cavity 28 that is radially open to the outside, from which the wire emerges axially at the end of the second axial movement, and [0225] d) rotating the winding support 21 back around the axis 44 with a second rotational movement until the needle winding device is once again aligned with the first longitudinal cavity, into which the winding wire is to be drawn.

[0226] Prior to the first rotational movement in step b), a linear movement of the needle winding device in the direction of the tool axis can be performed if necessary to draw the winding wire radially inward. Correspondingly a linear movement of the needle winding device in the direction away from the tool axis can be performed if necessary after the first rotational movement in step b) in order to draw the winding wire radially outward. The two radial movements are required if the rotational movement in step b) is performed with a comparatively small angle, so that the alignment of one or more fins 29 lies on a connecting line between the start point and end point of the rotational movement. In this case, there is a risk that the winding wire may not be positioned correctly in the annular space during the first rotational movement and second linear movement.

[0227] The aforementioned movements are repeated according to the N windings to be drawn in to form a coil 6. Naturally the aforementioned movements can also be performed by the respective other component in the sense of a kinematic inversion of the direction.

[0228] The first longitudinal coil segment 6a of a coil 6 is laid by the sum of the first axial movements, the second longitudinal coil segment 6b by the sum of the second axial movements. Furthermore, the first winding head segment 6c of the coil 6 is laid by the sum of the first rotational movements and the second winding head segment 6d by the sum of the second rotational movements.

[0229] Due to the cone 24 on the head of the winding support 21 with the fins 29, the first winding head segment 6c is automatically formed within the annular space between the fins 29 and the front winding support segment 22, i.e. offset radially inward relative to the teeth 3 of the stator assembly to which the fins 29 quasi correspond. The second winding head segment 6d on the other hand is formed axially in front of the fins 29 so that it later lies axially in front of the stator teeth 3.

[0230] The winding concept, or more precisely the assignment of the longitudinal cavities 28 to the individual coils, is carried out as previously explained in reference to FIG. 1c and FIG. 12a, 13f. Thus the second coil 6.2 of a phase is wound in diametrically opposite longitudinal cavities 28 and divided into two coil sections 6.2a, 6.2b that are routed in different circumferential directions from one longitudinal cavity to the other in order to obtain symmetrical winding heads 7, 8. This is shown in FIG. 15b with a view of the second winding head 8, which however initially consists only of this second coil 6.2 here.

[0231] The end and the start of the winding wire 11 of the second coil can be seen as well. The second coil 6.2 can be wound by fully winding the first coil section 6.2a completely and then winding the second coil section 6.2b completely, i.e. by initially producing all N/2 windings in the same direction sequence. Alternatively one winding of the first coil section 6.2a and one winding of the second coil section 6.2b can be wound alternately.

[0232] The two other coils 6.1, 6.3 of the phase are then wound one after the other, respectively in the two longitudinal cavities 28 that are adjacent to the longitudinal cavities 28 of the second coil 6.2 within the same circumferential semi-circle; see FIG. 1a, 13f. FIG. 15c shows the fixture 20 with wound first and second coils 6.1, 6.2, in which the first coil 6.1 lies radially on the first coil section 6.2a of the second coil 6.2 in the area of the second winding head segment 6d that is visible here.

[0233] All coils 6 of all phases can be initially wound in the illustrated manner and subsequently encapsulated together. With this full encapsulation, the coil assembly 5 forms a monolithic cast body (full cast body). As with the fixture 20 according to FIG. 9a-9c, a cover 32 is put over the mounting sleeve 47 for this purpose, a cylindrical first sleeve 30 encompassing the fins 29 is put over the fins 29 and the cylindrical second sleeve 31 is put over the cover 32 and the second winding head 8. Subsequently the winding tool 20 completed in this way is filled with sealant.

[0234] According to an alternative, only the coils 6 for a single phase U, V, W are wound and then encapsulated, and this is repeated for each phase, forming one cast body section per phase. With this partial encapsulation, the coil assembly 5 thus forms a multi-part cast body. The individual cast body sections are pushed together axially to form the coil assembly 5. This embodiment has the advantage that less force is required for demoulding the cast body sections compared to demoulding the full cast body and that the stress on the components is reduced overall. The same tool 20 can be used for all cast body sections.

[0235] However, the embodiment with cast body sections results in an axially larger constructed size of the winding heads 7, 8 by several millimetres, since each winding head 7, 8 has an insulating layer of sealant with a thickness of 1-2 mm respectively on its two axial face ends, and these are added up when stacking the cast body sections. The monolithic (one-piece) cast body on the other hand has a smaller axial constructed size of the winding heads for the same output or power density (up to 1.6 cm in total), because the coils lie closely against each other there without intermediate insulation. The performance of a coil assembly 5 produced as a full cast body is therefore better.

[0236] Note that the preceding description is merely exemplary for the purpose of illustration and in no way limits the scope of protection of the invention. Characteristics of the invention designated as can, exemplary, preferred, optional, ideal, advantageous, where applicable, appropriate or the like are merely elective and in no way limit the scope of protection, which is established exclusively by the claims. Insofar as elements, components, process steps, values or information are cited in the preceding description that have known, obvious or foreseeable equivalents, these equivalents are also covered by the invention. Furthermore, the invention encompasses all changes, variations or modifications of embodiments of the invention that involve the exchange, addition, change or omission of elements, components, process steps, values or information, as long as the fundamental concept according to the present invention is preserved, regardless of whether the changes, variations or modifications result in an improvement or an impairment of an embodiment.

[0237] Although the preceding description of the present invention identifies numerous material/immaterial characteristics or characteristics pertaining to the subject matter of the proceedings in reference to one or more concrete embodiment(s) of the invention, these characteristics can also be used in isolation from the concrete embodiment of the invention, at least insofar as they do not require the mandatory presence of additional characteristics. Conversely, these characteristics mentioned in reference to one or more concrete embodiment(s) of the invention can be combined at will with each other and with additional disclosed or undisclosed characteristics or embodiments of the invention that are not shown, at least to the extent that these characteristics do not mutually exclude each other or result in technical incompatibilities.