SYSTEM AND METHOD FOR INSERTING I-PINS INTO A STATOR OR ROTOR WINDING ASSEMBLY

A system and a method for inserting I-pins into a stator or rotor winding assembly are provided. The system has a cylindrical containment for hairpins and a circular inner containment axially inserted into the cylindrical containment for hairpins having a set of radial slots, an upper circular plate with one or more upper cam recesses, a lower circular plate with one or more lower cam recesses, and a vertical wall extending from the upper circular plate to the lower circular plate and rotatably mounted relative thereto. The upper and lower cam recesses accommodate a leg of the I-pins. The vertical wall has one or more voids positioned so that, upon rotation of the vertical wall with respect to the upper and lower circular plates, the upper and lower outlets lead into the voids releasing the leg in a radial slot of the cylindrical containment for hairpins.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to and benefit of Italian Patent Application No. 102023000007470 filed Apr. 18, 2023, the contents of which are incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a system and method for inserting I-pins into a stator or rotor winding assembly.

BACKGROUND ART

One of the ways of making flat-wire stator windings for electric motors is to cut conductor parts, bend them into suitable shapes, insert them into the stator pack, and join the conductor parts with welding joints according to a wiring diagram.

Names are defined according to the shapes and functions taken by the individual parts of a bent conductor.

To date, the most common flat-wire conductor shape is that shown inFIG.1and is commonly referred to as a “hairpin”100(with two legs, but there are some with a greater number of legs, such as the W-pin).FIG.2, on the other hand, shows a so-called “I-pin”200because the shape seems that of the letter “I” (a single leg). From the electrical point of view, its function inside the winding600(seeFIG.4) is to be the input and/or output of the same winding, and for this reason it is also referred to as a phase or route terminal. It should be noted that the term hairpin often mistakenly refers to all the shapes that the conductor can take before being positioned inside a winding600, thus including the I-pin itself.

FIG.2shows the main feature of the I-pin200, which is to have the straight (vertical) conductor parts201,202, which both end with a part without insulating enamel, one facing downwards,203, and the other upwards,204, unlike the hairpin100which has them both facing downwards. As a result, there are two oblique sections of the conductor in the hairpin100while there is only one in the I-pin200.

With reference toFIG.3, the wiring diagram of a stator winding (inserted into a containment305) determines whether or not to use the aforesaid I-pin as well as the slot and layer position.

The term ‘layer’ means the average diameter for positioning flat wires in the stator (or rotor) slot307, whereby outer layer302refers to the position of the flat wires301with the greatest diameter, while inner layer306refers to the position of the flat wires301with the smallest diameter, and intermediate layer303,304refers to all positions between the innermost layer and the outermost one.

In particular, in a wiring diagram, it is determined in which slots307of the stator pack the I-pins are to be inserted, and then in which layers302-306of the winding600, which is shown inFIG.4with I-pins200on the inner layer and inFIG.5with I-pins200on the outer layer.

A method for the insertion into the winding600is determined according to the layer in which the I-pin200is to be inserted. Usually, in a winding600there are more than one and in multiple numbers with respect to the number of phases.

Various positions of the I-pins200inside the windings of hairpins100can be observed inFIGS.4-6; in particular,FIG.4shows a winding600of hairpins100with I-pins200on the inner layer303,FIG.5shows a winding600of hairpins100with I-pins200on the outer layer302, andFIG.6shows a winding600of hairpins100with I-pins200on the intermediate layer304as well.

However, the insertion of the I-pins is not always simple and without consequence. Indeed, a first problem concerns the innermost I-pins of a winding, which, especially for small-diameter windings, are difficult to place from above by means of a robotic gripper. Indeed, the gripper would have to move radially from the inside to the outside and would interfere with the winding itself and/or other elements of the assembly apparatus.

In particular, there could be interference with hairpins next to the positions assigned to the I-pins.

This also generates the cycle time problem in the complete insertion of the I-Pin with a robot. Indeed, the “complicated” movement that would have to be performed with the robot would take too long for today's needs.

Another problem is that using a robotic gripper also causes the end portion201,204of the I-pin to be limited in length.

PURPOSE AND OBJECT OF THE INVENTION

It is the purpose of the present invention to provide a system and method for inserting I-pins into a stator or rotor winding assembly, as well as an apparatus for assembling the winding assembly and transferring it to a stator or rotor pack. The present invention relates to a system and a method according to the appended claims.

It is worth noting here that elements of different embodiments can be combined together to provide further embodiments without restrictions respecting the technical concept of the invention, as those ordinarily skilled in the art will effortlessly understand from the disclosure.

Moreover, the present disclosure also makes reference to the prior art for its implementation, as for the detail features not described, such as elements of minor importance usually used in the prior art in solutions of the same type, for example.

When introducing an element, it always means that there can be “at least one” or “one or more”.

When a list of elements or features is given in this disclosure, it is understood that the finding according to the invention “comprises” or alternatively “consists of” such elements.

When listing features within the same sentence or bulleted list, one or more of the individual features can be included in the invention without connection to the other features in the list.

Two or more of the parts (elements, devices, systems) described above can be freely associated and considered as kits of parts according to the invention.

DETAILED DESCRIPTION

A system for inserting I-pins200according to an embodiment of the present disclosure will be now illustrated, in the case in which they are to be inserted into the innermost layer303of the winding600(taking the traditional context shown above inFIG.3as an example). For this purpose, reference will also be made to a containment system which can be made in various manners, such as with retractable radial fingers, as disclosed in patent application PCT/IB2023/052123 to the Applicant, which is incorporated herein in its entirety by reference. See alsoFIG.7.

With reference toFIG.7, according to an aspect of the present disclosure, the winding600can already be partially formed, i.e., some of the hairpins100forming the winding600can already be positioned in the containment system450, the slots of which are formed between radially retractable elements or fingers or positioners455. The containment450ensures that the I-pins200, which will be inserted later, are supported on the plane transverse to the rotation axis of the containment. Regarding the vertical positioning (along said rotation axis) of the hairpins/I-pins, it is typically possible to use a support plate (not shown) below the free ends of the inserted hairpins.

The function of the containment system450is to keep each single hairpin in a stable position, i.e., to prevent the hairpin from falling toward the inside or toward the outside of the winding600. Moreover, it must allow inserting all types of hairpins which form a winding600.

A containment system as a single piece according to the prior art would have the disadvantage of not being capable of removing or moving the various parts serving the support functions for the hairpin. Therefore, according to the present disclosure, it is advantageous to use a containment system formed as several groups of parts, which individually perform the containment functions toward the inside of the winding600, toward the outside, and downwards.

In particular, as it can be seen inFIG.7, a central containment assembly500, positioned axially to the annular containment450, can be provided. The central containment500performs the dual function of inner containment for hairpins and positioning of I-pins.FIGS.8and9show how this assembly is composed of.

The central containment assembly500comprises two upper502and lower503plates (not to be confused with plate for supporting the legs of the hairpins) between which a cylindrical inner containment (vertical wall)501is inserted and connected. The central containment assembly500is configured to rotate the cylindrical inner containment part501and keep the two upper502and lower503plates fixed, or vice versa. The cams505and506are provided as notches to the plates502and503, respectively, and have a closed end505f,506fand an outlet505u,506u.They actually are cam-shaped guides for the legs of the I-pins200.

The cylindrical inner containment501can be made in various manners. For example, it can be a continuous wall (not shown) or one with vertical slits501s,which allow for a possible overtravel of radially retractable fingers455. However, as we shall see, there should be cylindrical sectors520in which such a wall is missing, in order to be able to make the I-pin exit from the outlets505u,506uwhen they are aligned with a cylindrical sector without a wall.

The central containment assembly500can be vertically moved by an arm550connected to the upper plate502.

The insertion method according to the present disclosure provides for the I-pins200to be transported, by any means, close to the aforesaid inner containment assembly501and housed inside the slots507obtained in the inner containment501, as it can be seen inFIG.10. As shown precisely inFIG.10, through the rotation of the cylindrical inner containment501and the concomitant action of the cams505,506obtained in the two respective upper and lower fixed plates502,503, the I-pins200are brought to their final position inside the winding600.

In other words, once the I-pin200is fully inserted into its own inner containment housing slot507, the rotation of the cylindrical inner containment501occurs, which together with the cams505,506of the upper502and lower503plates, respectively, create the thrust which moves the I-pin200to the final outlet position thereof through the (circular sector) opening520. Such a final position is shown inFIG.11.

Circumferentially, the slots507are between the radially retractable elements455but inside the containment500. This can be done with an overtravel of the retractable elements into the containment through slits501sor in a different way.

It should be noted again that the containment500is open over an arc of circumference520since the relative rotation of the plates and the central containment will bring the cam output at this arc of circumference and thus the I-pin will be pushed into the slots456of the containment450.

With reference toFIG.8, in order to position the I-pin precisely, the face of the upper circular plate502facing the lower circular plate can comprise upper radial containment elements502aarranged in a radial pattern, and the face of the lower circular plate503facing the upper circular plate can comprise lower radial containment elements503aarranged in a radial pattern. The two sets of elements are not necessarily the same in shape. The upper radial containment elements502aand the lower radial containment elements503aare configured so as to accommodate the leg202of an I-pin200between (the slots507) two consecutive upper502aand lower503aradial containment elements and to release the leg202exiting from said upper505uand lower506uoutlets into a radial slot456of said cylindrical containment450for hairpins.

The insertion of the I-pins200can also be multiple, i.e., multiple I-pins200can be inserted before rotating the cylindrical inner containment501, as shown inFIG.12, in which the hairpins and I-pins have been omitted to illustrate the four cams of the upper plate. Once an I-pin200has exited from the positioning cam505,506, it will be in the final position thereof in the winding600.

About the four slots, this number is entirely indicative. More precisely, whether it is the cams of the (upper or lower) inner containment or the outer containment, in a preferred case the one or more upper and lower cam recesses are a plurality of cam recesses, where:each cam recess subtends a number M≥1 of slot pitches, with M being an integer,between the upper and lower closed ends of a cam recess and the upper or lower outlet of the next cam recess, respectively, there is a distance of at least one slot pitch,
and where all cam recesses of the plurality of cam recesses are arranged in sequence in a predetermined arc of circumference. The I-pins are thus confined to that arc of circumference.

The rotation of the inner cylindrical containment501can be continuous until the final positioning of each I-pin200, or in discrete steps.

The same concept described above for the case in which the I-pins200are to be inserted into the innermost layer306of the winding600can be applied to the case in which they are to be inserted into the outermost layer302(FIG.3), as shown in detail inFIGS.13-16. In this case, the upper annular plate is indicated by512and has a cam515. A lower plate exists and it is always a plate for supporting the free ends of hairpins or I-pins, which do not necessarily have cams.

The outer containment annular plate512(only partially shown) is placed above said cylindrical containment450for hairpins (on the side of said upper plate502, if optionally present) or on the opposite side and, as mentioned, comprises one or more recesses515of outer containment annular plate with a closed end515fand an outer containment outlet515u,similar to those described above for the cylindrical inner containment. Such one or more recess515of outer containment annular plate are configured to accommodate the leg202of an I-pin200simultaneously extending into a radial slot456of said cylindrical containment450for hairpins, the one or more recesses515of outer containment annular plate being positioned so that, upon the relative rotation of the outer containment annular plate512with respects to the cylindrical containment450for hairpins, said outer containment outlet515uis positioned so as to lead radially toward said inner containment500and thus toward the winding600.

Also in this case of outer layer, the process and device allow simultaneously positioning multiple I-pins200in the winding600, as shown inFIGS.17and18(even more than one I-pin for each of the recesses).

A third case, in which the I-pins200are to be inserted into the intermediate layer304(seeFIG.3), can be considered a sub-case of the case described above, in which the I-pins200are inserted into the innermost layer303. Therefore, the same procedure as described above is used to mount the I-pin200in an intermediate layer304. The assembled winding600can be transferred from the containment450by pushing from above directly onto the stator pack700inserted from below with a lifting cylinder, as inFIG.19. The element470can be an additional upper containment or be part of the containment450.

With reference toFIG.20, an apparatus800is shown, which comprises an overall formation of the winding600with I-pins.

The apparatus800first comprises a rotary table, to work for example on two stations, one810A for assembling the winding under the hairpin inserter from the top and the other810B for inserting the winding into the stator pack,700simultaneously with very short rotation times of the table. It is preferable to rotate the table by 180° in one direction and then in the opposite direction so as to avoid complicated electrical and pneumatic connection systems. In all embodiments of the present invention, the two (or more) stations can be housed in corresponding holes of the rotary table. The table can also be configured to accommodate the storage (not shown) of any special basic conductors to be inserted into the transfer station.

The apparatus800further comprises a cylindrical containment assembly (not shown) in the station810A, which incorporates the containment450described above. It is worth adding that the teeth or positioners455(not shown, see figures above) can be pushed radially, in turn, by sliders (not shown) which transmit motion to the positioners and are preferably provided with springs (not shown). Moreover, the containment can have a connection for the transmission onto which a specific element, which allows the movement thereof (toothed wheel or belt pulley or other), configured to rotate the containment or the plates with the cams described above.

Since the thickness of the positioners455(the part in contact with the conductors) radially increases, the rotation of the cam can form more or less narrow slots similar to the stator ones. Therefore, the concept is to recreate wider slots during assembly and then narrower slots to align the basic conductors, with obvious advantages in the simplicity and effectiveness of assembly and insertion of the winding into the stator pack. The positioners can be conveniently guided by special guides provided in a containment cover element (not shown). Such guides can allow a given stroke to be maintained in all steps of operation. The radial movement of the positioners can be driven by cam mechanisms. The positioner455can also be shaped so as to have in section a first portion of radially inner end with a fixed thickness and then a second portion flared (wedge-shaped) toward the radially outer end. Advantageously, the second portion has a first sub-portion with a first sub-length having a first flaring angle and a second sub-portion, contiguous to said first sub-portion, with a second sub-length having a second flaring angle.

Again, the apparatus800inFIG.20optionally comprises an inner containment support assembly, e.g., with a fixed support (not shown) integral with the rotary table and a support structure which can be equipped depending on the size of the winding to be processed, in which to put the containment450with the inner containment500. For example, the inner containment500(adapted to prevent the basic conductors of the winding from falling radially inward and to insert the I-pins, see above) is supported by means of a support (not shown) rigidly connected to the fixed support, which connects the two assembly and insertion positions on the rotary table810in the 180° configuration.

A motor unit820of the cylindrical containment can allow both the entire cylindrical containment450and only the cylindrical wall of the inner containment500to rotate, through appropriate transmission means.

The apparatus800can comprise a stator positioning assembly830for the insertion of the winding, which aims at positioning the stator to receive the basic conductors and the I-pins within its slots (complete winding, seeFIG.19). It is devised to push the basic conductors from the top down through a single plane which simultaneously pushes all the conductors, and thus also serves the function of bringing the nape (part of the winding with the bridge portions of the hairpins) onto a single horizontal plane.

The foil-pack positioning and winding transfer assembly830can comprise means for opening and closing thrust half-rings (not shown) in order to avoid interference with other elements. The thrust means comprise means configured to move the two half-rings on a plane perpendicular to the winding axis from an open position to a closed position in which they form a single thrust disc of said head ends.

Finally, there is a base frame assembly760configured to take the rotary table810and all elements interacting therewith to a reference height. Table centering rollers and the stator pack raiser (not shown) can be fixed to this base frame, while the table rotation motor can be placed under the rotary table810.

In an aspect of the present disclosure, the procedure uses an apparatus800and comprises the following steps:1. inserting I-pins200into the innermost crown by means of the device810A described above;2. inserting I-pins into the intermediate crowns by means of the device810A described above;3. inserting one or more I-pins200into the outermost crown by means of the I-pin insertion device512described above;4. moving the partially assembled winding600to position810B, by means of the rotation of the rotary table810; and5. inserting the winding600into the stator pack.

ADVANTAGES OF THE INVENTION

With the method and system according to the present disclosure, the insertion of the I-pins is simple and without consequence. Indeed, without using a robotic gripper, the inner I-pins of a winding are easily positionable without interfering with the rest of the apparatus, the other I-pins, and/or the other hairpins.

Again, with the method and system according to the present disclosure, the problems of high cycle time that occur with traditional methods, e.g., with a robot, which has to make a more complicated movement, are overcome.

Moreover, since the apparatus acts in the center of the I-pins, the ends can be of any length, removing a limitation of the prior art.

Again, the system allows the I-pins to be inserted in the same station, which allows assembling a complete winding, thus without movements between stations.

Preferred embodiments have been described above and some variants of the present invention have been suggested, but it is understood that those skilled in the art may make modifications and changes without departing from the related scope of protection, as defined by the appended claims.