METHOD AND DEVICE FOR JOINING A COIL MAT TO A STATOR OF AN EXTERNAL ROTOR MOTOR

A joining method for joining a coil mat to the stator of an external rotor motor by: providing a coil mat having straight wire sections connected by winding heads, providing a stator with stator slots opening radially outwards, winding up the coil mat on a winding carrier which has radially outwardly opening winding carrier receiving slots, transferring the coil mat from the winding carrier to a transfer tool which has radially inwardly opening transfer tool receiving slots, and transferring the coil mat from the transfer tool to the stator. In addition, a joining device, a control unit and a computer program for carrying out the joining method.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of European Patent Application Number 23196368.7 filed on Sep. 8, 2023, the entire disclosure of which is incorporated herein by way of reference.

FIELD OF THE INVENTION

The invention relates to a joining method for joining a coil mat to a stator of an external rotor motor. The invention also relates to a joining device for joining a coil mat, which has straight wire sections connected by winding heads, in outwardly opening stator slots of a stator of an external rotor motor. The invention also relates to an (electronic) control unit and a computer program for such a joining device.

BACKGROUND OF THE INVENTION

A method for manufacturing a stator of an external rotor motor is known from [1], in which method a stator with stator slots opening radially outwards is provided and a wire bent in a wave-like or meandering shape is fed tangentially to the stator to form a wave winding and is wound onto a laminated core of the stator. In this way, a wave-shaped wire is inserted directly into the stator in a wind-up process.

This process is significantly improved in terms of process time and automation compared to previous processes for manufacturing stators for external rotor motors, in which process wires are wound around the teeth of the stator.

SUMMARY OF THE INVENTION

Based on [1], an object of the invention is to provide improved methods and devices for joining a coil winding to a stator of an external rotor motor.

This object may be achieved by the invention providing a joining method and a joining device according to one or more embodiments. Furthermore, a control system and a computer program for such a joining device are also disclosed.

According to one aspect thereof, the invention provides a joining method for joining a coil mat to a stator of an external rotor motor, the method comprising:a) providing a coil mat having straight wire sections connected by winding heads,b) providing a stator with stator slots opening radially outwards,c) winding up the coil mat on a winding carrier which has radially outwardly opening winding carrier receiving slots into which the straight wire sections are inserted,d) transferring the coil mat from the winding carrier to a transfer tool which has radially inwardly opening transfer tool receiving slots, the winding carrier receiving slots being aligned with the transfer tool receiving slots and the straight wire sections being transferred from the winding carrier receiving slots into the transfer tool receiving slots, ande) transferring the coil mat from the transfer tool to the stator, with the transfer tool receiving slots being aligned with the stator slots and the straight wire sections being transferred from the transfer tool receiving slots radially inwards into the stator slots.

Preferably, step a) comprises the step:a1) bending wires with a substantially rectangular cross-section and an outer insulating layer into wave winding wires.

Preferably, step a) comprises the step:a2) joining together a plurality of wave winding wires which are formed in a meandering shape with straight wire sections and winding heads bent in different directions therebetween.

Preferably, step a) comprises the step:a3) producing the coil mat by winding, stacking, braiding or pinning a plurality of wires.

Preferably, step a) comprises the step:a4) providing the coil mat on an elongate holder having a series of teeth with gaps between the teeth, such that the straight wire portions of the coil mat are received in the gaps between the teeth.

Preferably, step b) comprises the step:b1) providing a laminated core with radially outwardly opening stator slots.

Preferably, step b) comprises the step:b2) lining the stator slots with slot insulation.

Preferably, step b) comprises the step:b3) inserting insulation papers into the stator slots.

Preferably, step b) comprises the step:b4) covering slot edges with Z-shaped or Omega-shaped slot insulation.

Preferably, step c) comprises the step:c1) providing the winding carrier with a diameter equal to or greater than the diameter of the stator.

The term “equal” in step c1) and in step c6) explained further below is to be understood in the sense of “substantially equal”; diameters that differ slightly (e.g. 10%) from one another are still to be understood as “equal” in this sense.

Preferably, step c) comprises the step:c2) providing the winding carrier with radially movable ejector elements for radially ejecting the coil mat from the winding carrier receiving slots.

Preferably, step c) comprises the step:c3) providing an arrangement of radially movable support fingers axially adjacent to slot boundaries of the winding carrier receiving slots.

Preferably, step c) comprises the step:c4) providing the winding carrier with radially movable winding carrier slot limiting elements.

Preferably, step c) comprises the step:c5) picking up the coil mat from a linearly extending holder while rotating the winding carrier and relatively linearly moving the winding carrier and the holder.

Preferably, step c) comprises the step:c6) winding up the coil mat on the winding support with a wind-up diameter which is equal to or greater than the coil diameter of the coil mat subsequently inserted into the stator.

Preferably, step d) comprises the step:d1) providing the transfer tool with an annular arrangement of radially immovable or radially movable transfer tool slot limiting elements.

Preferably, step d) comprises the step:d2) providing radially movable support fingers axially adjacent to slot boundaries of the transfer tool receiving slots.

Preferably, step d) comprises the step:d3) radially moving the straight wire sections from the winding carrier receiving slots into the transfer tool receiving slots.

Preferably, step d) comprises the step:d4) radially expanding the coil mat during transfer from the winding carrier to the transfer tool by means of radially outwardly moving ejector elements.

Preferably, step d) comprises the step:d5) transferring the coil mat while maintaining the coil mat shape and/or the coil mat diameter by radially moving slot limiting elements of the winding carrier and the transfer tool.

Preferably, step d) comprises the step:d6) supporting and/or guiding the coil mat during transfer by means of radially feedable support fingers.

Preferably, step d) comprises the step:d7) holding the coil mat on the winding heads during transfer.

Preferably, step e) comprises the step:e1) radially compressing the coil mat during transfer onto the stator.

Preferably, step e) comprises the step:e2) guiding the coil mat during transfer by means of support fingers. Preferably, step e) comprises the step:e3) holding slot insulations in place when transferring the coil mat onto the stator.

Preferably, step e) comprises the step:e4) clamping slot insulations by means of support fingers.

Preferably, step e) comprises the step:e5) holding slot insulations in place by means of radial slot limiting elements of the transfer tool.

Preferably, step e3), e4) and/or e5) is followed by step e6) of releasing the slot insulations during the process, in particular during an insertion of the straight wire sections, in order to enable a transfer of the slot insulations together with the straight wire sections down to the bottom of the slots.

According to a further aspect, the invention provides a joining device for joining a coil mat which has straight wire sections connected by winding heads into outwardly opening stator slots of a stator of an external rotor motor, comprising:a winding carrier which has an annular arrangement of radially outwardly opening winding carrier receiving slots and on which the coil mat can be wound up under insertion of the straight wire sections into the winding carrier receiving slots; anda transfer tool which has an annular arrangement of inwardly opening transfer tool receiving slots and which is designed to receive the coil mat from the winding carrier and transfer it to the stator.

Preferably, the joining device further hasa rectilinear holder with at least one row of teeth for providing the coil mat anda wind-up device for rotating the winding carrier and for relative movement of the winding carrier and holder for winding up the coil mat on the winding carrier.

It is preferred that the winding carrier has radially fixed or radially movable winding carrier slot limiting elements.

It is preferred that the winding carrier has radially movable ejector elements for radially ejecting the coil mat for transfer to the transfer tool.

It is preferred that the winding carrier is held on a winding carrier handling device that is arranged to insert the winding carrier with wound-up coil into the transfer tool and to align the receiving slots of the winding carrier and the transfer tool with each other for transferring the coil mat.

It is preferred that the transfer tool has radially fixed or radially movable transfer tool slot limiting elements.

It is preferred that the transfer tool is held on a transfer tool handling device that is arranged to align the transfer tool with the winding carrier and the stator for the respective transfer of the coil mat.

In some embodiments, the joining device has at least one annular arrangement of radially movable support fingers for supporting and/or guiding the coil mat during transfer from the winding carrier to the transfer tool and/or during transfer from the transfer tool to the stator.

It is preferred that the arrangement of support fingers is arranged to clamp slot insulations inserted in stator slots to the stator when transferring the coil mat from the transfer tool to the stator.

Preferably, the joining device has a control unit with at least one processor and at least one memory adapted to control the joining device for carrying out the joining process according to one of the preceding configurations.

According to a further aspect thereof, the invention provides a control unit for a joining device according to one of the preceding embodiments, wherein the control unit is adapted to control the joining device for carrying out the joining process according to one of the preceding embodiments.

According to a further aspect thereof, the invention provides a computer program comprising instructions for causing a joining device according to one of the preceding embodiments to perform the joining method according to one of the preceding configurations.

Preferred embodiments of joining methods and joining devices are designed for the industrial mass production of stators of external rotor motors. As in [1], they are characterized by short process times and good automation capability.

An external rotor motor (also known as an external rotor for short) is a type of rotating electrical machine in which the stationary part (stator) of the machine is located inside and is enclosed by the moving part (rotor). Depending on the operating point and design, the machine can be used as an electric generator or as an electric motor. The preferred use of the external rotor motors that can be produced using methods and devices according to preferred embodiments of the invention is electromobility. For example, external rotor motors are to be manufactured in industrial mass production to be used as traction motors or traction drives for electrically powered vehicles (e.g. battery electric vehicles, hybrid vehicles or vehicles with fuel cells), such as in particular passenger cars or trucks. External rotor motors can be used, for example, as wheel hub motors for direct drive.

In particular, external rotor motors with high performance are to be manufactured. For this purpose, coil windings made of wires with a rectangular cross-section are particularly advantageous in order to achieve a high filling level.

Preferred embodiments are designed for stator production with wave winding. In this technology, which is generally known for stators of internal rotor motors, at least one prefabricated wire mat (prefabricated outside the stator)—referred to here as a coil mat—is inserted into the stator. A “coil mat” is understood to be a mat-shaped structure made of wave-shaped wires. A coil mat has a plurality of straight wire sections that are connected to each other by roof-shaped bent wire sections-winding heads. Such coil mats can be prefabricated in various ways, such as sword winding, stacking or pinning. Manufacturing methods for the coil mats are known and described in detail for instance from literature [2] and [3] as well as the documents cited in [2] and [3].

As described in [1], it is obvious for the production of stators for external rotor motors to attach prefabricated coil windings, such as individual wave winding wires, directly to the arrangement of outwardly opening slots of a laminated core of an external rotor stator. It is common practice to cover the slots with insulating paper beforehand.

In detail, however, there are difficulties with this technology, in particular the risk of damage to the wire and/or slot insulation paper. Due to the geometric conditions, the wires or insulation cannot be protected during direct wind-up of wave winding wires, or only with great effort. In particular, the sharp edges of the laminated core can very easily damage the wire-especially its outer insulating layer. In addition, the wire can displace the paper into the groove and damage it.

Preferred embodiments of joining methods and joining devices according to the invention are further improved over prior art according to [1] in terms of process reliability, reduction of rejects and/or reduction of damage to the coil winding.

Preferred embodiments of the invention relate to the manufacture of a stator for an external rotor (motor) with wave winding. In the wave winding concept, so-called winding mats (here called coil mats) are produced and then inserted into the laminated core.

Preferred embodiments relate to a concept for a series system for external rotor stators.

Preferred embodiments create a possibility (process or device) for joining the windings (in the form of a prefabricated wave winding or coil mat) to the stator with as little damage as possible or at least with a reduced risk of damage.

In an advantageous process according to embodiments of the invention and in combination with a transfer tool, component damage to the outer rotor can be reduced to a minimum and proven processes—in the field of manufacturing stators for inner rotor (motors)—can be used.

Some embodiments of the method have the following sequence of steps:

The wires/windings are wound onto a winding carrier (as for an internal rotor). In some embodiments, the diameter can (but does not have to) correspond to the stator diameter.

From this winding carrier, the wires are transferred (expanded) to a special transfer tool

The wires are joined (compressed) radially onto the stator by the transfer tool.

Simple elements can be inserted to protect the components. This reduces damage.

Other embodiments of the method have the following sequence of steps:

The wires/windings are wound onto a winding carrier (as with an internal rotor). The (winding) diameter is larger than the stator diameter so that additional expansion to a transfer tool is not necessary.

The wires are transferred from this winding carrier to a special transfer tool (without wire deformation).

The wires are joined (compressed) radially onto the stator by the transfer tool.

Simple elements can be inserted to protect the components. This reduces damage. In addition, the necessary deformation of the wires is reduced to a minimum.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments of a joining method and a joining device10for joining a coil mat12to a stator14of an external rotor motor are explained with reference to the accompanying drawings.

With reference toFIGS.1,2,6,8,12,24a-24c,15and29, the joining method comprises the steps:a) providing a coil mat12having straight wire sections18connected by winding heads16,b) providing a stator14with stator slots20opening radially outwards,c) winding up the coil mat12on a winding carrier22which has radially outwardly opening winding carrier receiving slots24into which the straight wire sections18are inserted,d) transferring the coil mat12from the winding carrier22to a transfer tool26which has radially inwardly opening transfer tool receiving slots28, the winding carrier receiving slots24being aligned with the transfer tool receiving slots28and the straight wire sections18being transferred from the winding carrier receiving slots24into the transfer tool receiving slots28, ande) transferring the coil mat12from the transfer tool26to the stator14, wherein the transfer tool receiving slots28are aligned with the stator slots20and the straight wire sections18are transferred radially inwardly from the transfer tool receiving slots28into the stator slots20.

An example of the coil mat12to be provided is shown inFIG.1. The coil mat12is prefabricated outside the stator14from at least one or preferably—as shown—several wave-like bent wires12a-12f. Examples of manufacturing processes for prefabricating the coil mat12and possible basic designs of the coil mat12are known from literature [2] and [3]. Accordingly, the coil mat12can be produced from the wires12a-12f, for example by winding, such as sword winding, stacking, pinning or braiding. The coil mat12is first designed on the basis of the desired configuration of the later coil winding in the stator14and then preferably manufactured from rectangular wire with an insulating layer in industrial mass production. In particular, the coil mat12is provided on a rectilinear holder30, as is generally known from [6] and [7].

As indicated inFIG.9, the elongate holder30may have a series of teeth30awith gaps30bbetween them, so that the straight wire sections18of the coil mat12are accommodated in the gaps30b.

In some embodiments, the distances between the straight wire sections18are already selected according to the planned radial position of the wire sections18in the stator14. Distances A41, A51, A31 between the tooth gaps30bcan be correspondingly designed differently.

Examples of embodiments for the stator14are shown schematically inFIGS.2,6,6,14-16, as well as18and19. The stator14has—as is generally well known—a laminated core32, on the outer circumference of which the arrangement of outwardly opening stator slots20is formed.

As can be seen in particular fromFIGS.18and19, the stator14is provided in particular with slot insulations34. For this purpose, insulating papers are inserted into the stator slots20beforehand. Devices and methods for inserting insulation papers are known for internal rotor stators from literature [4] and [5]. These known technologies can easily be used to provide the pre-insulated stator slots20shown inFIGS.18and19by modifying them accordingly to adapt them to the changed geometry of external rotor stators with outwardly opening stator slots20. In particular, slot edges on the stator slots20are covered with Z-shaped or Omega-shaped slot insulations34.

According toFIG.2, the stator14prefabricated in this way is provided in particular on a stator holder36. The stator holder36can be stationary or can be movably arranged on a stator handling device38—e.g. robot arm, conveyor belt, portal system,

A schematic overview of an embodiment of the joining device10for carrying out the joining process is shown inFIG.2. The joining device10is designed for joining the coil mat12, which has straight wire sections18connected by winding heads16, into the outwardly opening stator slots20of the stator14of an external rotor motor.

The joining device10has the winding carrier22and the transfer tool26.

In some embodiments, the joining device10further comprises an electronic, in particular computer-implemented control unit40with a processor40aand a memory40b, in which a computer program with instructions for carrying out the joining method is stored.

Examples of embodiments of the winding carrier22are shown inFIGS.3,4,8,9as well as20and21. Accordingly, the winding carrier22has an annular arrangement of radially outwardly opening winding carrier receiving slots24, such that the coil mat12can be wound up under insertion of the straight wire sections18into the winding carrier receiving slots24. The winding support receiving slots24are bounded by winding carrier slot limiting elements42. The design of the winding carrier slot limiting elements42can be very different. In particular, joining mandrels can be provided as winding carriers22, as are known for joining coil mats in internal rotor stators, for example from literature [6], [7] or [8].

For winding up the coil mat12, some embodiments of the joining device10have a wind-up device44, examples of which are shown inFIGS.2,8and9. In particular, the winding carrier22is arranged on a winding carrier handling device46which can be controlled by the control unit40and by means of which the winding carrier22can be moved linearly relative to the holder30and can be set in rotation in order to wind up the coil mat12. In some embodiments, the winding carrier handling device46, as indicated by the double arrow, is arranged to move the winding carrier22towards the transfer tool26in order to transfer the coil mat12onto the transfer tool26.

Winding up the coil mat12on the winding carrier22and designs of the winding carrier22are known for methods for joining coil mats to internal rotor stators from literature [6] and [7]. The same technologies can also be used here.

Examples of embodiments of the transfer tool26are shown inFIGS.2,5,7,10-16,17,18and19and22-29. The transfer tool26has the annular arrangement of inwardly opening transfer tool receiving slots28and is arranged to receive the coil mat12from the winding carrier22and transfer it to the stator14. The transfer tool receiving slots28are each bounded by transfer tool slot limiting elements48.

In some embodiments, the transfer tool26is arranged in particular on a transfer tool handling device50which can be controlled by the control unit40and by means of which the transfer tool26can be moved relative to the winding carrier22and the stator holder36with the stator14. In some other embodiments, the transfer tool26is held stationary and the relative movements of the winding carrier22, transfer tool26and stator holder36are performed by moving the winding carrier22by means of the winding carrier handling device46or by moving the stator handling device38.

Examples of the handling devices38,46,50are robot arms, linear transport systems and portal systems. The handling devices38,46,50can have further actuators that can be controlled by the control system40, in particular for the controlled radial movement of individual elements of the winding carrier22or transfer tool26or stator holder36.

In the following, a first embodiment of the joining device10and a joining method that can be carried out with it is explained in more detail with reference to the illustration inFIGS.3to19.

According toFIGS.3and4, the winding carrier slot limiting elements42of the winding carrier22are arranged or held rigidly or stationary according to the first embodiment. For example, the winding carrier22has an outer diameter that is (substantially) equal to the stator diameter. In some embodiments, the diameter of the winding carrier22is larger than the stator diameter. In principle, the diameter of the winding carrier22can also be smaller than the stator diameter, but this is less preferred, as this leads to more deformation steps for the coil mat12during the process.

The winding carrier22also has at least one ejector element52between adjacent winding carrier slot limiting elements42, which ejector element is radially movable under the control of the control unit40in order to eject the coil mat12radially during subsequent transfer to the transfer tool26. For example, the ejection elements52are radially movable expanding plates.

In particular, the ejection elements52can be moved radially from their rest position, in which they are retracted at least to the radial height of a slot base53of the respective winding carrier receiving slot24or further radially inwards, into an ejection position for complete ejection of the straight wire sections18from the winding carrier receiving slots24and for transfer into transfer tool receiving slots28and back again by means of an actuator with a corresponding transmission (not shown) controlled by the control unit40. Examples of such radially movable elements are known to the skilled person from wave winding technology for internal rotor stators, see e.g. [6]-[8].

According toFIG.5, the transfer tool26of the first embodiment is annular or sleeve-shaped with an internal diameter such that the stator14can be accommodated with little play between them. The transfer tool slot limiting elements48are, for example, rigid rib-like projections projecting radially inwards.

In some embodiments, an example of which is shown inFIG.7, an annular arrangement of radially movable support fingers54is provided on each axial side of the transfer tool26.

In particular, a support finger54is provided on each axial side of each transfer tool slot boundary element48. In some embodiments, the support fingers54are wedge-shaped. The support fingers54are configured to guide the wire sections18during insertion of the wire sections18into the transfer tool receiving slots28and during transfer of the wire sections18from the transfer tool receiving slots28into the stator slots20. For this purpose, the support fingers54are radially movable under the control of the control unit40. In particular, the support fingers54can move together with the wire sections18over at least a partial distance. Here too, corresponding actuators controlled by the control unit40, for example a transmission, can be provided (not shown).

In some embodiments, an example of which is shown inFIGS.18and19, the support fingers54are designed to hold and/or clamp the slot insulations34. For example, the support fingers54have a projection56on the side facing the transfer tool slot boundary element48, which projection can move onto the stator slot boundaries58between the stator slots20by a radially inward movement of the support finger54for transferring the coil mat12to the stator14and can thus clamp the slot insulations placed over the slot edges of the stator slots20. The slot insulations34can be released again by a corresponding counter-movement in order to compress the wires together with the slot insulations (paper)34completely to the slot base of the stator slot20.

The sequence of the joining process according to the first embodiment is explained in more detail below with reference to the illustrations inFIGS.2,8,9,3,4and10to19.

In a first step, the coil mat12is wound up on the winding carrier22. Winding up is carried out as explained in [6] or [7] and shown inFIGS.8and9. The winding carrier22and holder30with coil mat12provided on it are moved linearly relative to each other. For example, the holder30can be moved in the longitudinal direction towards the winding carrier22or the winding carrier22is moved linearly over the holder30by means of the winding carrier handling device46, or both movements take place. In the process, the winding carrier22is rotated. By means of support elements not shown, such as curved ramps or other guides or belts or the like, which engage the winding heads16, the coil mat12is lifted off the holder30and placed on the winding carrier22in such a way that the straight wire sections18are inserted into the winding carrier receiving slots24. The winding diameter can (but does not have to) correspond to the subsequent coil diameter on the stator14.

The holder30, for example in the form of a rake, and the winding carrier22can be adapted to the previously designed shape of the coil mat12by special geometries, as shown inFIG.9, so that wire damage is reduced.

In a second step, the winding carrier22is inserted concentrically into the transfer tool and the winding carrier receiving slots24are aligned with the transfer tool receiving slots28, as shown inFIG.10. This is done by means of one or more of the handling devices46,50, controlled by the control unit40.

Then, as shown inFIGS.11to13, the coil mat12is transferred from the winding carrier22to the transfer tool26. For this purpose, the coil mat12is expanded as indicated by the arrows inFIG.12, i.e., enlarged from a smaller wind-up diameter, with which the coil mat12is located on the winding carrier22, to a larger take-up diameter, with which the coil mat12is located in the transfer tool26.

The expansion takes place in particular by a radially outward movement of the ejector elements52.

If the slot limiting elements42,48of the winding carrier22and transfer tool26are close together, the expansion can also be carried out without additional guides. Preferably, the expanding is guided by the support fingers54as shown inFIG.13, which are moved to a radially inwardly extended guide position before the expanding and are held there during the expanding in some embodiments. In some embodiments, the support fingers can also be moved along with the wires12a-12f.

This results in the situation shown inFIG.11, in which the straight wire sections18are completely received in the transfer tool receiving slots26.

In a third step, which is shown inFIGS.14to19, the coil mat12is transferred from the transfer tool26to the stator14.

For this purpose, the stator14and the transfer tool26are arranged concentrically to each other by means of one or more of the handling devices38,50, so that their slots20,28are aligned with each other, as shown inFIG.14.

The wires12a-12fare then transferred from the transfer tool26to the stator14by means of radially movable grippers, belts or sliders, not shown, which engage on the axially outwardly projecting winding heads16, whereby the wire sections18are inserted into the receiving grooves. In the process, the coil mat12is compressed, i.e., its diameter is reduced from a larger receiving diameter, with which it is received in the transfer tool26, to a smaller coil diameter, which the coil mat12assumes on the stator14as intended.

This can also be supported by the support fingers54, as shown inFIG.15, but does not have to.

FIGS.18and19show an embodiment variant. Accordingly, the support fingers54can clamp the slot insulations34(here formed as Omega-shaped folded paper) when joining the coil mat12to the stator14. This prevents the paper from being displaced into the groove when the wire sections18are inserted. For the sake of simplicity, this is shown inFIGS.18and19with only one support finger54and without wires. In the further course of inserting the wire sections18, in some embodiments, the slot insulations34are released again by a corresponding counter-movement of the support fingers54in order to enable the slot insulations to be pushed together with the wires down to the slot base of the stator slots20.

In the following, a second embodiment of the joining method and the joining device10are explained with reference to the illustration inFIGS.2,8,9,20-29.

As shown inFIGS.20and21, the winding carrier22according to the second embodiment has radially movable winding carrier slot limiting elements42(e.g., in the form of lamellae). For example, actuators not shown are provided for this purpose, possibly with transmission, which are controlled by the control unit40and which initiate the radial movement of the slot limiting elements42. In particular, the winding carrier slot limiting elements42have a step58for forming a part of the respective slot base of the associated winding carrier receiving slot24.

According toFIGS.22and23, the transfer tool slot limiting elements48of the transfer tool26according to the second embodiment are also radially movable and are designed in particular as lamellae. The radial movement of the transfer tool slot limiting elements48is also controlled by the control unit40. Steps60are also provided here, which form part of the slot base of the transfer tool receiving slots28.

In one embodiment variant, the transfer tool26according to the second embodiment can also be used together with the arrangements of support fingers as described above and shown inFIGS.7and17-19.

In the following, a second embodiment of the joining method is explained with reference to the illustration inFIGS.8,9,24a-29.

In a first step, the coil mat12is wound up on the winding carrier22shown inFIG.20in a manner comparable to that shown inFIGS.8and9. In some embodiments, this has a larger diameter than the diameter of the stator14. In particular, the winding diameter with which the coil mat12is wound up on the winding carrier22is larger than the stator diameter, so that additional expansion at the transfer tool26is not necessary. In preferred embodiments, the winding carrier slot limiting elements42are positioned radially for winding so that the winding diameter of the coil mat12on the winding carrier22corresponds to the receiving diameter of the coil mat12on the transfer tool26when the latter is put on the stator14.

In a second step, which is shown in detail inFIGS.24a-24cand in an overview inFIGS.25to27, the coil mat12is moved from the winding carrier22onto the transfer tool26—preferably with little or no deformation. For this purpose—as already described above for the first embodiment—winding carrier22and transfer tool26are first arranged concentrically to one another and aligned with their receiving slots24,28to one another.

Then the winding carrier slot limiting elements42are moved radially inwards, while at the same time the transfer tool slot limiting elements48are moved radially inwards in order to enter between the wire sections18. Thus, rather than the wire sections18not moving or moving only slightly, the slot limiting elements42,48are moved radially to transfer the coil mat12.

Thus, in some embodiments, wires12a-12fof the coil winding are transferred from the winding carrier22to the transfer tool26in such a way that the wires12a-12fretain the diameter and shape as much as possible. The lamellae of the winding carrier22retract and the lamellae of the transfer tool26simultaneously retract between the wires12a-12f. In this way, the coil mat12is transferred without having to be deformed.

In addition, elements such as retaining rings on the winding heads16(not shown) can prevent the coil mat12from slipping during this process of transferring from the winding carrier22to the transfer tool26. It is also possible to use the support fingers54during this process.

In a third step, the coil mat12is transferred from the transfer tool26to the stator14. For this purpose, the transfer tool26and the stator14are first arranged concentrically and aligned with their slots28,20, as already described above for the first embodiment.

Then, as described above for the first embodiment, the coil mat12is transferred from the transfer tool26to the stator14, for example using radially movable grippers, sliders or belts (not shown) which engage the winding heads16, and is radially compressed in the process. In particular, the diameter of the coil mat12is compressed from the larger receiving diameter to the smaller coil diameter with which the coil mat12is arranged on the stator14as intended.

In some design variants of the second embodiment, the transfer tool slot limiting elements48are moved even further radially inwards from the radial position shown inFIG.20and thus clamp the slot insulations34on the outer circumference of the stator14between the stator slots20when the wires12a-12fare inserted into the stator slots20. Accordingly, the radially displaceable lamellae of the transfer tool26can also clamp or hold the paper. Clamping takes place in particular when the wires are inserted; in the further course, the slot insulations34can be released again so that they can move together with the wires down to the bottom of the stator slots20.

In some variants of the second embodiment, the transfer of the coil mat12from the transfer tool26to the stator14is guided by the support fingers54as described above for the first embodiment. When used in the second embodiment, the support fingers54can also be designed as shown inFIGS.18and19and hold the slot insulations during transfer.

Accordingly, the movements can be guided by support fingers54during transfer: The support fingers54prevent damage to the wires12a-12fat the sharp edges of the laminated core32.

Although only a single coil mat12has been mentioned in the various embodiments, it should be clear that more than one coil mat12can be joined to the outer rotor stator14using the methods and devices illustrated herein. If several coil mats12are used, they can be wound up and transferred together or transferred one after the other.

Further, support fingers54may also be associated with the winding carrier22, for example, a radially movable support finger with an outwardly directed thinner end may be arranged axially adjacent to each winding carrier slot limiting element42.

A relative movement of the transfer tool and the winding carrier or stator holder can take place in different ways. For example, the transfer tool can be moved with the transfer tool handling device50, but it can also be held stationary and the relative movement is performed by the other handling devices46,38.

In order to improve process reliability in the industrial mass production of stators for external rotor motors, a joining method for joining a coil mat (12) to the stator (14) of an external rotor motor has been described, comprising:a) providing a coil mat (12) having straight wire sections (18) connected by winding heads (16),b) providing a stator (14) with stator slots (20) opening radially outwards,c) winding up the coil mat (12) on a winding carrier (22) which has radially outwardly opening winding carrier receiving slots (24),d) transferring the coil mat (12) from the winding carrier (22) to a transfer tool (26) which has radially inwardly opening transfer tool receiving slots (28), ande) transferring the coil mat (12) from the transfer tool (26) to the stator (14).

In addition, a joining device (10), a control unit (40) and a computer program for carrying out the joining method have been described.

The systems and devices described herein may include a controller or a computing device comprising a processing and a memory which has stored therein computer-executable instructions for implementing the processes described herein. The processing unit may comprise any suitable devices configured to cause a series of steps to be performed so as to implement the method such that instructions, when executed by the computing device or other programmable apparatus, may cause the functions/acts/steps specified in the methods described herein to be executed. The processing unit may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof.

The methods and systems described herein may be implemented in a high-level procedural or object-oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of the controller or computing device. Alternatively, the methods and systems described herein may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems described herein may be stored on the storage media or the device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein.

Computer-executable instructions may be in many forms, including modules, executed by one or more computers or other devices. Generally, modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically, the functionality of the modules may be combined or distributed as desired in various embodiments.

It will be appreciated that the systems and devices and components thereof may utilize communication through any of various network protocols such as TCP/IP, Ethernet, FTP, HTTP and the like, and/or through various wireless communication technologies such as GSM, CDMA, Wi-Fi, and WiMAX, is and the various computing devices described herein may be configured to communicate using any of these network protocols or technologies.

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