Method and apparatus for manufacturing a stator for an electric motor

Abstract

A method and apparatus for manufacturing a star yoke stator for an electric motor with distributed windings are described, as well as a stator obtained by the described method. The two-component stator includes a central star-shaped element with radial stator teeth and stator slots interposed between the teeth, and a yoke into which the star is inserted with the windings contained within the stator slots. The assembly method provides for positioning the star on a rotating spindle and inserting straight sections of a wire coil, preformed on a winding tool and preferably pressed and carburized, into the stator slots to maintain a neat wire arrangement. The winding is completed by alternating the insertion of the coil into the stator slots and the rotation of the star. The yoke can be joined to the star in a final step if the yoke is made in one piece, or it can be built around the star by joining sectors of the yoke as the winding is completed. An apparatus configured to implement the described method is also described. The invention further relates to a stator obtained directly by the described method and an electric motor incorporating the stator. Greater packing factors, higher efficiency, lower leakage currents, and reduced stator height are achieved.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for manufacturing a stator for an electric motor, in particular a two-component stator (also called a star yoke stator), and to a stator manufactured by such a method. [Background technology]

[0002] As is well known, the stator of an electric motor is generally cylindrical in shape, with a plurality of fixed poles formed by stator teeth arranged along the inner circumference of the cylinder and projecting toward a common central axis that coincides with the axis of rotation of the rotor that is combined with the stator in the completed electric motor, following a coaxial configuration with the stator on the outside and the rotor on the inside.

[0003] One or more windings (also called coils) of conductive wire are arranged in sectors defined by the spaces between the stator teeth, more commonly called stator slots.

[0004] Some stators have concentrated windings, where the conductive wire is wound around each individual stator tooth, while others have distributed windings, where the conductive wire is wound around two or more teeth. The present invention is particularly concerned with the manufacture of distributed winding stators.

[0005] In the prior art, to manufacture a distributed winding stator, the cylindrical body of the stator is first fabricated by assembling the teeth, separately fabricating one or more coils of conductive wire on the outside of the stator body, and inserting these coils into the stator slots of the already formed cylindrical body.

[0006] The ends of the stator teeth are commonly called pole pieces. In conventional stators, openings (called slot openings) of sufficient size to allow for the insertion of coils exist between the pole pieces of two adjacent teeth.

[0007] However, there are stators that do not allow coil insertion using the above method because they do not have slot openings. An example is the star yoke stator. These are two-component stators: an outer cylindrical body, commonly called the yoke, and an inner body, commonly called the star, constructed from a bundle of laminated metal sheets. The star derives its name from its geometric configuration: an inner cylindrical surface defined by the pole pieces of all stator teeth, with the stator teeth themselves extending radially outward from the inner cylindrical surface. The inner cylindrical surface of the star is essentially continuous, except for small windows or openings created to reduce the stator's weight and minimize electromagnetic short-circuiting. Therefore, coils cannot be inserted between the pole pieces of adjacent stator teeth; instead, they are inserted into the stator slots from the outside before the star is inserted into the yoke.

[0008] In a two-component or star yoke stator, the yoke is a cylinder suitably machined so that its inner surface forms seats for receiving the stator teeth of the star and locking them in place once the coupling (interference fit) between the yoke and the star is complete. Thus, in a star yoke stator, the stator slot is bounded circumferentially by the two stator teeth and radially by the inner cylindrical surface of the same star defined by the pole pieces of the stator teeth and the inner surface of the yoke.

[0009] An example of a star yoke stator is described in US2015 / 0054378, where paragraph 29 mentions that various techniques can be used to create windings on the stator teeth according to the desired filling factor. This document shows a star yoke stator with concentrated windings, i.e., a coil wound on each stator tooth. In this configuration, a needle winding machine can be used to create the windings on the stator teeth. If the windings are distributed windings, the coils are created on a winding tool outside the stator and then manually inserted onto two stator teeth.

[0010] In general, as in conventional star yoke stators, it is desirable to maximize the sector packing factor, i.e., to be able to insert as many conducting wires as possible, or the same number of wires of different diameters, in the same sector, which leads to improved performance of the electric motor. The packing factor is defined as the ratio of the cross-sectional surface occupied by the conducting wires in the stator slots to the total area available in the stator slots (always considered in cross section).

[0011] Maximizing the packing factor also allows, other factors being equal, to minimize the stator height and produce a more compact electric motor.

[0012] A further limitation is that after the coil is inserted into the stator, the individual loops that make up the coil are always positioned so that some loops are always towards the centre of the stator and others are always towards the outside of the stator, which increases the leakage current of the motor and consequently reduces the efficiency of the motor itself.

[0013] WO 2022 / 084760 in the name of the applicant describes a method that allows maximizing the packing factor of different types of stators for star yoke stators. The method provides for pre-forming the coils with a suitable winding tool outside the stator before inserting them into the stator slots. The invention includes the following methods:

[0014] The method of coil manufacturing includes one or more conductive wires being wound on a winding tool to form at least one coil consisting of at least one straight section, including a plurality of individual straight wire sections, and intended to be inserted into one of the sectors of a stator.

[0015] a coil accommodation step in which a straight portion of the coil is inserted into a stator part including some of the plurality of parallel teeth, particularly between two adjacent stator teeth;

[0016] a forming step in which the stator part containing the straight portion of the coil is deformed to move the parallel stator teeth closer together to achieve a finished stator part including two teeth that together define a sector in which the straight portion of the coil is contained and constrained;

[0017] An assembly step in which a plurality of completed stator sections achieved through the respective encasing and forming steps are assembled to form a complete stator body including windings.

[0018] After the forming step, with the coils already seated in the stator slots, the method further provides for performing a rotational translation R1 of the first completed stator section relative to the second completed stator section, where the first and second completed stator sections engage the same coils. The rotational translation continues until the first completed stator section reaches a relative position within the completed stator body relative to the second completed stator section, resulting in deformation of the coils.

[0019] As an alternative to step R1, before the forming step, i.e., before inserting the coils into the stator slots, the method provides for performing a rotational translation R2 of the first stator component relative to the second stator component until the first stator component reaches a relative position in the finished stator body relative to said second stator component, thereby deforming the coils in accordance with the arrangement of the rotationally translated first and second stator components, and then proceeding to the coil receiving step.

[0020] The method described in WO 2022 / 084760 is not applicable to star yoke stators, since deformation of the star to bring the stator teeth closer and constraint of the coils in the slots is not provided for in this type of stator, nor is there provision for making the star in deformable and assemblable sectors: in the star, the stator teeth extend radially to the final position that each tooth will assume in the finished stator.

[0021] JP2022137412A in the name of Mitsubishi Electric Corporation describes a method for assembling a stator starting from a linear (flat) support. The coils are pre-wound on a winding tool and then all inserted together onto the linear support before winding the linear support one full turn onto a cylindrical element. Thus, deformation of the coils occurs simultaneously for all coils as the linear support is wound.

[0022] Patent IT102021000011564 in the name of the applicant describes a method for manufacturing a stator, which includes:

[0023] - forming a coil on a winding tool to form at least one coil including at least one straight wire portion intended to be inserted into a corresponding stator sector;

[0024] - performing a pressing and carburizing process, in which the straight portion of at least one coil is subjected to a thermal carburizing process and pressed to consolidate the straight wire portion;

[0025] a coil accommodation step in which a straight portion of the coil is inserted between two parallel stator teeth of a stator component;

[0026] - a forming step in which the stator part is deformed to bring the two parallel teeth closer together and surround the straight part of the coil to achieve a finished stator part;

[0027] an assembly step in which a plurality of completed stator sections are assembled to form a stator body; Summary of the Invention

[0028] It is an object of the present invention to provide a method and apparatus for manufacturing a star yoke stator for an electric motor to overcome the limitations of currently available solutions and maximize fill factor.

[0029] A further object of the present invention is to implement a method and an apparatus for manufacturing a star yoke stator that, all factors being equal, makes it possible to achieve a more compact stator in terms of height (stacking height) compared to stators manufactured with known solutions.

[0030] The invention relates to a method according to claim 1 for manufacturing a star yoke stator for an electric motor, in particular a two-component stator with distributed windings, the two-component stator comprising:

[0031] an outer body called the yoke, and

[0032] - a body within the yoke, called the star, having an inner cylindrical surface that defines the accommodation volume of the rotor of the electric motor, and a number of radial stator teeth that project from the cylindrical surface towards the yoke and have stator slots between them intended to accommodate windings of conductive wire.

[0033] The method includes:

[0034] A) a conductive wire coil manufacturing step in which one or more conductive wires are wound on a winding tool to form at least one coil including a plurality of individual straight portions of the conductive wire, the straight portions being arranged in an orderly manner and suitable for insertion into a stator slot;

[0035] C) supporting the star on a rotation axis with at least one first stator slot accessible to a manipulator for the coil;

[0036] D) inserting, by a manipulator, a first straight portion of the coil into at least one first stator slot and constraining a second straight portion of the coil outside the star;

[0037] E) rotating the star by a predetermined angle about the axis of rotation, thereby deforming the coil in the sections contained between the straight sections and making at least one second stator slot accessible to the manipulator and ready for the insertion of each straight section of the coil;

[0038] F) inserting, by the manipulator, a second straight portion of the coil into at least one second stator slot;

[0039] G) Repeating steps D, E and F until the star winding is complete, i.e., until a straight section of coil has been inserted into each stator slot;

[0040] H) The method includes the step of restraining the star to the yoke according to one of the two methods described below.

[0041] The step E of rotating the star is repeated until the stator is completed at each stop of the star, where a straight portion of the coil is inserted into the respective stator slot. The rotation E is therefore intermittent and ends when all stator slots have been completed with a straight portion of the coil. Thus, in the claimed solution, the straight portions of the coil are inserted one at a time into the respective stator slots, and the precisely intermittent rotation E of the star is synchronized with the insertion operations D and F, in particular the rotation E of the star alternates with the insertion operations D and F of the manipulator. The deformation of the coils therefore also occurs intermittently, and not simultaneously for all coils.

[0042] The rotation stage therefore provides for rotating the star through an angle corresponding to the angle between the first and second stator slots (not necessarily adjacent to each other), but at an angle less than 360°, preferably less than 180°, after which the star is stopped and from there proceeds to step F. In step F, the star is kept stationary.

[0043] Steps D, E and F are sequential and step G is performed in the same order, repeating them until the stator is complete, i.e., the stator is equipped with all the necessary windings.

[0044] The above-described method makes it possible to achieve further different effects.

[0045] An improved filling factor of the stator sectors is one of the achievable advantages. The Applicant has determined that, all other things being equal, this method makes it possible to achieve a filling factor that is at least 20% greater than that of star yoke stators manufactured according to known techniques, i.e., those manufactured with standard insertion of windings into the stator slots.

[0046] The method according to the invention also allows the production of stators with reduced losses in the windings, approximately 30% less at low rotational speeds and approximately 20% less at high rotational speeds compared to stators assembled with standard insertion of coils between the slots and teeth.

[0047] In terms of efficiency, when the solution according to the invention is compared with a stator achieved with standard slot filling techniques, it is found that, other things being equal (same size / power, same number of poles, same size of the slots between the teeth, same diameter of the conductive wires, same rotor and same stacking height), the stator achieved in the above-mentioned way makes it possible to achieve, at low rotational speeds, an efficiency of about 1-1.4% greater than that of a motor assembled with a standard stator.

[0048] Furthermore, at low rotational speeds, motors assembled with stators manufactured according to this method will produce approximately 4-5% more power than motors with standard stators, and even more, up to 20%, at high rotational speeds, all things being equal (same size / power, same number of poles, same size of slots between teeth, same diameter of conductive wire, same rotor and same stack height).

[0049] The method according to the invention also entails advantages in terms of the axial dimensions of the finished motor. Once the motor size is set, for example for 55 kW, a significant reduction in the stack height including the stator and the individual windings is achieved, since this method allows the manufacture of a stator with an increased filling rate of the slots between the teeth. Comparing a standard stator with a stator achieved with this method, a reduction in stack height of up to 35% is achieved.

[0050] A further advantage is that the individual loops making up the coils are arranged so that the first straight section of the coil is towards the centre of the stator and the second straight section of the same coil is towards the outside of the stator, creating a position reversal that helps to minimise leakage currents in the motor.

[0051] The method according to the invention makes it possible to manufacture in an economical and simple manner the stator of an electric motor, including its respective windings, as will be described in detail in this application.

[0052] A further advantage of the described solution is that deformation occurs to individual coils at a time, which is given for each angular movement of the star. Deformation does not occur simultaneously for all coils, which makes it possible to achieve greater structural precision and improved tolerances compared to when one or more coils are substantially all deformed simultaneously, as is the case, for example, with JP 2022137412 A. The rotation of the star of the present invention is a rotation between two successive stops of the star-shaped support, which corresponds exactly to the angle between the first and second slots, and should not be confused with the rotation of the star-shaped support described with JP 2022137412 A.

[0053] More specifically, in step E, the star is rotated about its axis of rotation by an angle corresponding to the electrical phase of the finished stator and is stopped in this angular position to accommodate a further straight section of coil, or further straight sections of coil, in the corresponding stator slot. Each rotation imparted to the star thus has the purpose of providing the manipulator with a new stator slot to be filled with a straight section of coil previously made by the winding tool.

[0054] In a preferred embodiment, the method further includes an otherwise optional pressing or carburizing step B, in which at least one of the straight sections of the coil undergoes a pressing step, a thermal carburizing step, or both a pressing step and a thermal carburizing step simultaneously in a desired order to consolidate the individual straight wire sections according to the orderly arrangement achieved during the coil-forming step A. Advantageously, the wires of the straight sections of the coil that have undergone the pressing and carburizing steps remain cohesive and do not separate or displace relative to each other. This detail allows the windings to be created and maintained in the best possible geometric configuration to maximize the fill factor for each stator slot size to be filled and avoids fraying during coil movement. Furthermore, the straight wire sections can be shaped perfectly complementary to the stator slots into which they must be inserted.

[0055] Preferably, step B lasts from 15 seconds to 2 minutes.

[0056] Preferably, during the pressing and / or carburizing step B, the straight portion of the coil is pressed with one or more pressing elements and heated by one or more heating devices contained in or coupled to the pressing elements while the coil is being wound on the winding tool, i.e. before the coil is removed from the winding tool.

[0057] In a possible method, in pressing and / or carburizing step B, the thermal carburizing treatment is carried out by inserting one or more heating elements between the straight sections of the coil and heating them to a predetermined carburizing temperature, typically in the range of 170°C-210°C.

[0058] In a possible method, in the pressing and / or carburizing step B, the straight sections are pressed by a pressing device which is inserted between said straight sections of the coil after removing the heating element, while keeping the coil housed in the winding tool.

[0059] In a possible method, in coil manufacturing step A, a complementary, thinner conductive wire having a cross section smaller than the cross section of the main conductive wire is added to the conductive wire, called the main wire, with the complementary conductive wire occupying the free space between the main parallel conductive wires.

[0060] Preferably, the method further comprises the step of insulating the conductive wire.

[0061] - if provided, applied to at least the straight section of the coil after pressing and / or carburizing step B, or

[0062] -applied between the teeth of the stator components before the coil insertion step D.

[0063] Preferably, coil manufacturing step A is implemented by making a series of multiple coils on the same winding tool, making sure to keep straight sections of a coil spaced apart from straight sections of subsequent coils according to a predetermined pitch distance corresponding to the pitch between the stator slots in the star.

[0064] Preferably, prior to step E and during coil insertion step D, first straight portions of a series of coils are simultaneously inserted into corresponding stator slots of the star. Later, subsequent to step E, second straight portions of the same series of coils are simultaneously inserted into corresponding stator slots of the star such that corresponding windings are distributed among the stator slots. The non-linear portions of the coils are subject to deformation caused by the rotation of the star. This deformation causes the coils to assume the shape required for proper insertion of each straight portion into its respective stator slot according to the pitch defined by the electrical phase.

[0065] This method can be implemented in two modes.

[0066] In a first mode intended to manufacture a stator with an integral yoke, between steps D and E and between steps F and G, the following is provided:

[0067] In steps D' and F', the stator slots, together with each straight section of coil contained therein, are temporarily closed by a stator slot closing device. This device is movable between a retracted position, in which the stator slots are radially open and accessible to the manipulator, allowing the insertion of straight sections of coil, and an advanced position, in which the stator slots are radially closed, preventing the exit of straight sections of coil. This detail is intended to prevent the coils from accidentally detaching from the star during rotation.

[0068] Initially, when the coil manipulator approaches the star after taking the coil from the winding tool, and during step D of inserting the first straight portion of the coil into the respective stator slot of the star, the first straight portion is kept flush with the second straight portion of the coil. In other words, the coil is initially moved while maintaining the shape it was taken from the winding tool, i.e., the coil remains undeformed. In contrast, the coil undergoes deformation during step E, when the first straight portion of the coil is inserted into the corresponding stator slot and the second straight portion is constrained by the manipulator, causing the star to rotate. In this situation, the coil is deformed at the portion connecting the first straight portion to the second straight portion.

[0069] Preferably, steps C through G are performed within the inner cylindrical surface of the winding device, with the star supported on a spindle, e.g., a drum. In practice, the star is coaxially fitted to the spindle, with the stator teeth arranged radially and projecting toward the inner cylindrical surface of the winding device. This detail ensures that the stator slots are precisely radially enclosed by the inner cylindrical surface of the winding device. This inner cylindrical surface has a longitudinal through-hole that provides the coil manipulator with radial access to the first stator slot of the star. Thus, only the stator slot, into which the straight portion of the coil must be inserted at any given time, is located within the longitudinal opening and remains accessible from the outside. Meanwhile, the remaining stator slots and the remainder of the star remain enclosed between the spindle and the inner cylindrical surface of the winding device.

[0070] In a first embodiment of the method, steps D and F are carried out by locating the stator slots intended to accommodate the straight sections of the coils in the longitudinal openings by rotating the star, and keeping the star stationary during the insertion of the straight sections.

[0071] As a result, the rotation of the star alternates with the insertion of the manipulator into the coil.By repeating the alternating rotation of the star and the insertion of straight sections of the coil by the manipulator, the winding on the star is completed.

[0072] In a first embodiment of this method, the yoke is substantially cylindrical and made in one piece, and step H is carried out by pulling the star from the spindle and inserting it with all the windings into the yoke.

[0073] In a second embodiment of this method, the yoke is made as a set of sectors, and step H is realized by a specific manipulation system which manipulates the sectors of the yoke sequentially between steps E and F and between steps F and G, by taking the sectors of the yoke from the star, constraining the sectors in the stator slots into which the straight portions of the coils have been inserted, and achieving closure of the stator slots from the outside.

[0074] Thus, in a first embodiment of the method, the stator slots are closed by a closing device, and in a second embodiment, the stator slots are closed by sectors of a yoke applied to the star.

[0075] Preferably, step H is carried out by temporarily restraining the sectors of the yoke to both the star and the spindle on which the star is supported by means of removable fastening elements, and the finished yoke, i.e. the yoke once completed, is held together by a jaw system.

[0076] A further aspect of the present invention relates to a two-component or star yoke stator as claimed in claim 18, which is achieved directly by the method described herein. A stator achieved directly by the method described is, all things being equal, distinguishable from stators produced by known techniques for the following reasons:

[0077] - When considering conductive wires with a circular cross section, the filling factor is improved by at least 20%.

[0078] The conductive wires defining the straight sections of the coils contained within the slots of the stator sectors are arranged according to an orderly and repeatable matrix arrangement, rather than the close but random arrangement of the known art.

[0079] The stator slots have a substantially rectangular cross section, unlike the trapezoidal slots of known solutions, with straight sections of the coils having a cross section of a shape complementary to the cross section of the stator slot.

[0080] The invention further relates to an electric motor integrating the above-mentioned stator in a version in which the yoke is made integral or in a version in which the yoke is realized by assembling yoke sectors.

[0081] A further aspect of the invention relates to an apparatus for manufacturing a star yoke stator of the type described above according to claim 20. The apparatus comprises:

[0082] - at least one winding tool configured to perform step A, wherein one or more conductive wires are wound on the winding tool to form a coil including at least one straight portion comprising straight portions of a plurality of individual conductive wires, the coil being adapted to be inserted into one of said stator slots.

[0083] A spindle rotatable about a rotation axis and lockable in a plurality of angular positions, comprising:

[0084] - supporting the star during the step CG, so that at least one first stator slot of the star is accessible to the coil manipulator; and

[0085] - rotating the star through an angle corresponding to making at least one second stator slot accessible to the coil manipulator, with the possibility of deforming the coil in the sections included between the straight sections during step E.

[0086] a coil manipulator configured to perform step D by inserting a first straight portion of the coil into a corresponding stator slot and constraining a second straight portion of the same coil, and to perform step F by inserting the second straight portion of the coil into a corresponding stator slot.

[0087] The spindle supports the star coaxially on the axis of rotation. The rotation of the star alternates with the insertion of the coil manipulator, so that after a straight section of the coil is inserted into a corresponding stator slot, the star rotates to position an additional stator slot in the manipulator's orbit, allowing for the insertion of an additional straight section of the coil or the same coil.

[0088] Preferably, the winding tool includes a support frame supporting a series of angular elements, each series arranged substantially along an edge of an ideal parallelepiped, the angular elements of each series spaced apart from one another to define a corresponding series of winding chambers for receiving the conductive wire or bundles of conductive wires forming the coil, the winding chambers being spaced apart at a pitch corresponding to the desired pitch formed between the straight portions of the coil.

[0089] Preferably, the apparatus further includes a wire guidance device including an axial guide having a plurality of wire guide tubes that slide independently of one another in a controlled manner, each wire guide tube being crossed and guided by one or more layers of wire intended to form layers of loops. The wires may be a main wire having a nominal cross section and a thinner complementary wire having a cross section smaller than the nominal cross section.

[0090] Preferably, the apparatus includes a pressing device for carrying out step B, i.e., for pressing the straight portion of the coil. The pressing device includes a plate having coupled thereto a series of inclined surfaces adapted to contact the straight portion to be pressed.

[0091] Preferably, the apparatus includes a heating device for carrying out step B, i.e., for carrying out the thermal carburization treatment of the straight sections of the coil. The heating device includes one or more heating elements, preferably by induction, shaped and arranged to be inserted between the straight sections of the coil.

[0092] In a preferred embodiment, the coil manipulator includes a first gripper (upper gripper) and a second gripper (lower gripper). The lower gripper is configured to take first straight sections of the coil from the winding tool, hold them for a required time, and push them into the first stator slot. The upper gripper is configured to take second straight sections of the coil from the winding tool, hold them for a required time, and push them into the second stator slot.

[0093] The upper and lower grippers are movable relative to each other between:

[0094] an initial coplanar position in which the coil is not deformed relative to its initial configuration on the winding tool; and

[0095] -Multiple graduated positions of the gripper in different planes and / or at different heights, allowing straight sections of the coil to be inserted at once into stator slots at different angular positions of the star of the stator to be assembled.

[0096] In other words, the grippers move relative to each other and relative to the spindle and star, allowing both insertion of straight sections of the coil and deformation of the coil at non-straight sections.

[0097] Preferably, the gripper comprises a push-out element operable to push the straight portion of the coil out of the gripper itself for insertion into the stator slot, in other words the gripper comprises jaws for restraining the straight portion of the coil for the time required to move from the winding tool to the spindle and star, and also comprises a push-out element operable to push the straight portion of the coil out of the jaws of the gripper and into the stator slot.

[0098] In a first embodiment suitable for manufacturing a stator with an integrally made yoke, the apparatus comprises a support structure to which the spindle is constrained, and a carriage, which is movable relative to the spindle and / or relative to the support structure, for example on a track, between:

[0099] a first position in which the carriage does not block the spindle and the star supported by the spindle is not trapped within the carriage, i.e. the carriage does not surround the star; and

[0100] - A second position in which the carriage extends around the spindle and encloses the star supported on the spindle.

[0101] The carriage has an inner cylindrical surface complementary to the star supported on the spindle, in the sense that the clearance available between the stator teeth and the inner cylindrical surface is minimal, sufficient to allow the star to rotate but to prevent the coils from emerging from the stator slots. The inner cylindrical surface opens outward with longitudinal through-openings into which the coil manipulators are inserted to accommodate the straight sections of the coil in each stator slot of the star. In effect, the carriage surrounds the star supported on the spindle, and the longitudinal openings allow the insertion of the straight sections of the coil in a radial direction from the outside.

[0102] In this embodiment, there is a closing device configured to temporarily and on command close the longitudinal opening, in effect intervening to temporarily close the longitudinal opening and prevent the coils from accidentally escaping from the stator slots before the star rotates and the straight section moves into the area confined by the carriage.

[0103] Preferably, the closure device is a slide, drawer or shutter type device with a panel mounted on a carriage and movable between two positions.

[0104] In the retracted position, the panel does not block the longitudinal opening, allowing the manipulator to be inserted through the longitudinal opening and into the stator slot of the star supported on the spindle; and

[0105] In the forward position, the panel blocks the longitudinal opening and prevents the straight section of the coil from escaping from the stator slot.

[0106] In a second embodiment suitable for manufacturing a stator having a yoke formed by assembling sectors, the apparatus includes a system for manipulating the sectors of the yoke, the manipulating system comprising at least one gripper with movable jaws for gripping / releasing the sectors of the yoke, the gripper being movable to a position for releasing the sectors that close one or more stator slots already equipped with straight sections of coils, where the sectors are fixed to the star.

[0107] In this second embodiment, the apparatus includes one or more fastening elements carryable by the handling system with each yoke sector, the fastening elements configured to keep the yoke sector constrained to the spindle during assembly of the stator, and removable after assembly is complete.

[0108] Preferably, the fastening elements are fork-shaped, engage with the two longitudinal ends of the sectors of the yoke and can be inserted into corresponding seats present on the spindle, the fork shape allowing these fastening elements to straddle the straight sections of the coils inserted into the star stator slots.

[0109] More specifically, a fork-shaped element engages each yoke sector and has at least one tooth insertable into a seat of the spindle. The spindle includes at least one lever, the teeth of the fork-shaped element snap-engage with a corresponding lever. The lever is movable to release the teeth of the fork-shaped element and allow release of the fork-shaped element when it is no longer useful, i.e., when the yoke is assembled.

[0110] Preferably, the seats for inserting the fork-shaped elements are arranged circumferentially on the spindle according to a pitch proportional to or corresponding to the pitch between the sectors of the yoke. The spindle comprises at least one lever for each seat, each lever swinging on a pin and opposed by a spring. The lever also has teeth intended to engage with the teeth of each fork-shaped element. All the fork-shaped elements can be disengaged and released from the spindle by controlling the swing of all the levers.

[0111] Preferably, the spindle is cylindrical and the levers are arranged radially on the spindle, with the pins arranged tangentially, i.e. perpendicular to each lever.

[0112] In its two versions, the described device assembles the stator according to the invention and thus makes it possible to realize the described advantages in a fast, precise and fully automated assembly. [Brief explanation of the drawings]

[0113] Further characteristics and advantages will become apparent from the description of preferred but non-exclusive embodiments of the stator manufacturing method according to the invention, given by way of example and without limitation by the accompanying drawings, in which: FIG.

[0114] [Figure 1] FIG. 1 is a flow diagram illustrating a method for manufacturing a star yoke stator according to the present invention.

[0115] [Figure 2] FIG. 2 is a front view and elevational view of the method according to the present invention and a winding machine used to produce coils that can be used in a stator.

[0116] [Figure 3] FIG. 3 is a detailed view of the machine of FIG.

[0117] [Figure 4] FIG. 4 is a detailed cross-sectional view of the machine of FIG. [Figure 5] FIG. 5 is a detailed cross-sectional view of the machine of FIG. [Figure 6] FIG. 6 is a detailed cross-sectional view of the machine of FIG.

[0118] [Figure 7] FIG. 7 is an exploded view of a winding tool associated with the machine of FIG. [Figure 8] FIG. 8 is an exploded view of a winding tool associated with the machine of FIG.

[0119] [Figure 9] 9A to 9C are perspective views of the winding tool of FIG. 7 in successive steps. [Figure 10] 10 is a perspective view of the winding tool of FIG. 7 in successive steps.

[0120] [Figure 11] 11 is a side view and an elevation view of the winding tool shown in FIG.

[0121] [Figure 12] 12 is a cross-sectional view of the winding tool of FIG. 7 along a different plane. [Figure 13]13 is a cross-sectional view of the winding tool of FIG. 7 along a different plane. [Figure 14] 14 is a cross-sectional view of the winding tool of FIG. 7 along a different plane.

[0122] [Figure 15] 15 is a perspective view of an individual coil produced with the machine of FIG. 2 and the winding tool of FIG.

[0123] [Figure 16] 16 is a perspective view of a number of coils produced with the machine of FIG. 2 and the winding tool of FIG.

[0124] [Figure 17] FIG. 17 is a perspective view of an apparatus for pressing and carburizing coils.

[0125] [Figure 18] FIG. 18 is a cross-sectional view of the apparatus of FIG. 17 during successive coil pressing and carburizing. [Figure 19] FIG. 19 is a cross-sectional view of the apparatus of FIG. 17 during successive coil pressing and carburizing.

[0126] [Figure 20] FIG. 20 is a perspective view of an alternative embodiment of a winding tool. [Figure 21] FIG. 21 is a perspective view of an alternative embodiment of a winding tool.

[0127] [Figure 22] 22a, 22b and 22c are cross-sectional views of different possible types of winding loops.

[0128] [Figure 23] 23a, 23b and 23c are cross-sectional views of different types of winding loops according to optional solutions.

[0129] [Figure 24]FIG. 24 is a perspective view of a detail of a further embodiment of a winding tool.

[0130] [Figure 25] 25 is a front view of the winding tool of FIG. 24. FIG.

[0131] [Figure 26] 26 is a side view of the winding tool of FIG. 24. FIG.

[0132] [Figure 27] 27 is a top view of the winding tool of FIG. 24. FIG.

[0133] [Figure 28] 28A is a perspective view showing two successive steps of a heat treatment process performed on a coil housed in the winding tool of FIG. 24. FIG. [Figure 29] FIG. 29 is a perspective view showing two successive steps of a heat treatment process carried out on a coil housed in the winding tool of FIG.

[0134] [Figure 30] FIG. 30 is a cross-sectional view of an electric motor with a star yoke stator according to the known art.

[0135] [Figure 31] FIG. 31 is a perspective view of a star according to the known art.

[0136] [Figure 32] FIG. 32 is a perspective view of a stator star sector portion according to the present invention.

[0137] [Figure 33] FIG. 33 is a cross-sectional view of the star yoke stator of the first embodiment according to the present invention, without windings.

[0138] [Figure 34] FIG. 34 is an isometric view of the completed windings of the star yoke stator shown in FIG.

[0139] [Figure 35] FIG. 35 is a cross-sectional view of a star yoke stator of a second embodiment according to the present invention, without windings.

[0140] [Figure 36] FIG. 36 is an isometric view of the completed windings of the star yoke stator shown in FIG.

[0141] [Figure 37] FIG. 37 is a perspective view of a gripper system used in an apparatus according to the present invention for manipulating coils for manufacturing star yoke stators in both embodiments shown in FIGS. 33-34 and 35-36, respectively.

[0142] [Figure 38] FIG. 38 is a cross-sectional view of the gripper system shown in FIG.

[0143] [Figure 39] 39A and 39B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 40] 40A and 40B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 41] 41A and 41B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 42] 42A and 42B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 43]43A and 43B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 44] 44A and 44B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 45] 45A and 45B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 46] 46A and 46B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 47] 47A and 47B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 48] 48A and 48B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 49] 49A and 49B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 50] 50A and 50B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 51] 51A and 51B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 52] 52A and 52B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 53] 53A and 53B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 54] 54A and 54B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 55] 55A and 55B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 56] 56A and 56B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 57] 57A and 57B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 58] 58A and 58B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 59] 59A and 59B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 60]60A and 60B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots. [Figure 61] 61A and 61B are perspective views of a first apparatus according to the invention for manufacturing a star yoke stator according to the first embodiment shown in FIGS. 33 and 34 at different steps during the insertion of coils into the stator slots.

[0144] [Figure 62] 62A and 62B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 63] 63A and 63B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots.

[0145] [Figure 64] FIG. 64 is a perspective view of components of a second embodiment of a device according to the present invention.

[0146] [Figure 65] FIG. 65 is a cross-sectional (vertical) view of the components shown in FIG. [Figure 66] 66A and 66B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 67] 67A and 67B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 68]68A and 68B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 69] 69A and 69B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 70] 70A and 70B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 71] 71A and 71B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 72] 72A and 72B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 73] 73A and 73B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 74] 74A and 74B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 75] 75A and 75B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 76] 76A and 76B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 77] 77A and 77B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots. [Figure 78] 78A and 78B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 79] 79A and 79B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 80] 80A and 80B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 81] FIG. 81 is a perspective view of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots. [Figure 82] 82A and 82B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 83] FIG. 83 is a perspective view of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots. [Figure 84] FIG. 84 is a perspective view of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots. [Figure 85]FIG. 85 is a perspective view of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots. [Figure 86] FIG. 86 is a perspective view of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots. [Figure 87] 87A and 87B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 88] FIG. 88 is a perspective view of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots. [Figure 89] FIG. 89 is a perspective view of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36, at different steps during the insertion of coils into the stator slots. [Figure 90] 90A and 90B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots. [Figure 91] 91A and 91B are perspective views of a second apparatus according to the invention for manufacturing a star yoke stator according to the second embodiment shown in FIGS. 35 and 36 at different steps during the insertion of coils into the stator slots.

[0147] [Figure 92] FIG. 92 is a schematic diagram of a winding layout of a star yoke stator according to known technology, in cross section and in a table of the respective technical requirements of the windings.

[0148] [Figure 93]FIG. 93 is a schematic diagram of five possible layouts of the windings of a star yoke stator according to the invention in cross section and a table of the respective technical requirements of the windings.

[0149] [Figure 94] FIG. 94 is a cross-sectional view of a portion of a hypothetical star yoke stator having stator slots filled in a conventional manner compared to the same stator slots filled in a manner in accordance with the present invention.

[0150] [Figure 95] FIG. 95 is a diagram of losses in relation to rotational speed, all things being equal, for a motor made with a star yoke stator according to known technology and a motor made with a star yoke stator according to the present invention.

[0151] [Figure 96] FIG. 96 is a diagram of efficiency in relation to rotational speed, all things being equal, of a motor made with a star yoke stator according to known technology and a motor made with a star yoke stator according to the present invention.

[0152] [Figure 97] FIG. 97 is a diagram of power output in relation to rotational speed, all things being equal, for a motor made with a star yoke stator according to known technology and a motor made with a star yoke stator according to the present invention. Detailed Description of the Invention

[0153] To achieve a high fill factor, in a star yoke stator according to the present invention, the windings are formed by manufacturing coils featuring a highly orderly arrangement of conductive wires in a suitable tool outside the stator, and then inserting the coils into the stator slots.

[0154] FIG. 1 is a flow diagram summarizing the main steps of a method according to the present invention for manufacturing a star yoke stator with distributed windings.

[0155] Step A is the manufacture of the coil 4. The method optionally and preferably includes step B of pressing and / or carburizing the coil, providing that step B is performed either pressing only, or carburizing only, or both pressing and carburizing in any desired order or simultaneously.

[0156] Step C provides that the stars 100 of the stators S1, S2 are coaxially fitted onto the spindles 501, 601, with the stator teeth 104 projecting radially outwards from the spindles 501, 601 and the first stator slots 106 being externally accessible.

[0157] Step D provides for manipulating the coil 4 previously fabricated in step A, and possibly also in step B, to insert a first straight portion 4b of the coil 4 into the first stator slot 106 and to constrain or fix a second straight portion 4a of the same coil 4.

[0158] Step E provides for rotating the spindles 501, 601, and therefore the star 100, through an angle useful for making the second stator slot 106 accessible from the outside, thereby causing a simultaneous deformation of the coil 4.

[0159] Step F provides for inserting the second straight portion 4 a of the coil 4 into the second stator slot 106 .

[0160] Step G provides for repeating steps D, E and F until the winding is complete, i.e. until the straight portions 4a, 4b of the coil 4 have been inserted into each stator slot 106.

[0161] The yokes 101', 101'' are assembled to the star 100 in step H, which can be carried out during the previous step.

[0162] In the first embodiment, the spindle 501 on which the star 100 of the stator S1 is fitted rotates within a cylindrical surface 508, and the straight portions 4a, 4b of the coils 4 are constrained within the respective stator slots 106 by the cylindrical surface 508. In the second embodiment, the yoke 101'' of the stator S2 is configured with sectors 110, and the straight portions 4a, 4b of the coils 4 are constrained within the respective stator slots 106 by at least one sector 110 of the yoke 101'' that is coupled to the star 100.

[0163] In the first embodiment, step H' provides for completing the stator S1 by removing the star together with the windings from the spindle 501 and inserting it into the respective yoke 101'. In the second embodiment, step H'' provides for completing the stator S2 by fixing all sectors 110 of the yoke 101'', for example with the jaw system 700.

[0164] 2-29, as previously mentioned, the method first involves step A of manufacturing a coil 4, in which one or more conductive wires 14 are wound on a winding tool 20 to form at least one coil 4 comprising at least one, preferably two, straight portions 4a, 4b comprising a plurality of individual straight wire portions 14. Each straight portion 4a, 4b of the coil 4 is intended to be inserted into a stator slot defined by a star of the stator. The coil 4 thus manufactured is actually formed by a plurality of loops of the wire 14.

[0165] In this step, the coil 4 is preferably manufactured with at least one first 4a and at least one second 4b straight section parallel to each other and connected by a non-linear section, and the first 4a and second 4b straight sections are then inserted into different stator slots 106, respectively.

[0166] As shown in the figure, the coil 4 is preferably produced in a continuous series on the winding tool 20, the series including a plurality of first linear portions 4a and corresponding second linear portions 4b, e.g., three, suitably spaced apart according to a pitch distance corresponding to the pitch between the stator slots 106 of the star 100.

[0167] Only one coil 4 as in FIG. 15 or multiple coils 4 in series as in FIG. 16 are wound on the winding tool 20 depending on the design decisions.

[0168] The windings can be made from one or more parallel wires, making it possible to obtain, for example, a coil 4 with one hundred loops made from only one wire 14, or fifty loops made from two parallel wires, or ten loops made from ten parallel wires 14, etc.

[0169] A possible embodiment of a winding machine 200 that can be used to manufacture the coil 4 is shown in FIG.

[0170] The winding machine 200 includes a support structure 201 that supports:

[0171] a plurality of wire tensioning devices 203 (of known type) for tensioning the wire 14 being wound;

[0172] a wire guide device 206 comprising a wire guide tube 204 and movable along a wire guide 205 (preferably made of a bar);

[0173] a winding spindle 244 rotated by the motor 214 and adapted to rotate the winding tool 20 described below, in fact coupled to a sleeve for engagement on the spindle 25;

[0174] Such a winding machine 200 can be configured in an operational winding configuration in which the wire 14 to be wound is tensioned and exits the wire tensioning device 203 towards a wire guidance device 206, which in turn guides the wire 14 towards the winding tool 20 which continues to rotate.

[0175] Optionally, winding machine 200 further includes a tailstock 215 positioned coaxially with spindle 244 and adapted to be coupled to removable wall 24 ′ of winding tool 20 .

[0176] FIG. 3 shows details of the wire guiding device 206 including a base 217 to which a wire guiding element 216 (preferably a pair of wheels) is fixed, which guides the wire 14 into a wire guide tube 204 located at the end of the base 217 facing the winding tool 20.

[0177] 4 and 5. It is preferably present in the winding machine 200 and is positioned coaxially with the spindle 244, aligning the wire 14 exiting the wire guide tube 204 into a loop before being wound onto the winding tool 20.

[0178] 6 shows a cross section of a wire guide tube 204 made up of multiple sectors defining multiple separated ducts 251 for the wires 14, with a wire 14 held in position within each duct 251 for forming layers of loops. In the example shown, there are three ducts 251, and the wires are arranged in three layers in a 5-4-5 configuration (five wires in the first layer, four in the second layer, and five in the third layer), resulting in a total of 14 parallel wires for each loop, each wire 14 being fed and managed by one of the fourteen wire tensioning devices 203 visible in FIG. 2.

[0179] Obviously, the number of wires 14 wound parallel to each loop (and therefore the number of wire tensioning devices 203), the number of layers (and therefore the number of ducts 251 in the wire guide tube 204), and the number of wires 14 per layer can be varied and selected according to the requirements of the project.

[0180] A first embodiment of the winding tool 20 is shown in Figures 7-14, and a second embodiment is shown in Figures 20-21 and 24-29.

[0181] 7-14, the winding tool 20 preferably includes a plurality of movable walls 22 contained between a fixed wall 23' and a removable disassembly wall 24'.

[0182] The fixed wall 23' is configured to be operatively coupled to the winding spindle 244 to drive the rotation of the movable wall 22, and optionally includes a sleeve for engagement with the spindle 25 for this purpose.

[0183] The removable breakaway wall 24' can be separated from the fixed wall 23' to release the movable wall 22 and allow the already wound coil 4 to move.

[0184] The movable wall 22 defines one or more winding chambers 24 into which the conductive wire 14 is wound to form the coil 4 .

[0185] More particularly, the fixed wall 23 further includes a wire clamping element 26 configured to clamp the wires 14 (already arranged in the appropriate configuration) entering the winding.

[0186] For convenience, the fixed wall 23' further comprises a centering pin 27 which projects towards the removable wall 24' and engages in a tunnel formed by a central hole 28 provided in the center of each movable wall 22, for centering the movable walls 22.

[0187] The end of the centering pin 27 has a hook end 271 for engaging the fixed wall 23' with the removable wall 24'.

[0188] The fixed wall 23' further comprises a plurality of (four in the illustrated example) axial positioning pins 231 which similarly protrude towards the removable wall 24' and have the function of maintaining the proper axial position of the movable wall 22 during winding by occupying respective positioning holes 29 provided in the movable wall 22 during winding, thereby ensuring the proper size of the winding chamber 24.

[0189] As can be noted in the figure, the axial positioning pin 231 is formed by a plurality of longitudinal portions of different diameters, which decrease towards the removable wall 24', and the positioning holes 29 have different diameters in each movable wall 22, which decrease towards the removable wall 24', and each movable wall 22 is fixed to a respective longitudinal portion of the axial positioning pin 231.

[0190] The movable walls 22 maintain an axial dimension (determined by the thickness of the walls 22 and the distance between the walls 22 themselves) during the winding step of the conductive wire 14 (manufacturing the coil 4), but can approach each other under the thrust of the press during the pressing step described below. Such an axial dimension is conveniently ensured by mechanical reference elements 291, which ensure the repeatability of the process and the consistency of the final dimensions of the pressed coil 4. In practice, the winding tool 20 is configured so that the movable walls 22 can approach each other under the action of pressure up to a distance determined by the mechanical reference elements 291, which act as limit stops.

[0191] The number of movable walls 22 in the winding tool 20 is determined by the number of coils 4 to be manufactured in series + 1 (equal to the number of coils per electrode and therefore per sector 3). Thus, by the formula Np = nm + 1, Np is the number of movable walls 22 and nm is the number of coils. In fact, nm coils are coils 4 that are part of individual electrodes.

[0192] The movable wall 22 is substantially rectangular in plan, both in vertical and horizontal cross section. Preferably, the movable wall 22 is provided with an operating seat 249 on the side projecting outward from the winding tool 20.

[0193] In preferred embodiments, each movable wall 22 is formed by a central support 221 and two winding cheeks 222 fixed on either side of the central support 221, in which case the operating seat 249 is obtained in the winding cheeks 222. In fact, in these embodiments, the winding chamber is defined between the winding cheeks 222.

[0194] Preferably, insulation is interposed between the central support 221 and the winding cheeks 222 to limit heat loss during the hot carburization process described below.

[0195] The removable disassembly wall 24' is removable in the sense that it can be separated from the fixed wall to allow the movable wall 22 to be extracted.

[0196] In a preferred embodiment, the removable wall 24 also includes respective wire clamping elements 261 configured to clamp the wires 14 exiting the windings and keep them arranged in the appropriate configuration.

[0197] The removable wall 24' comprises a coupling device 241 for direct or indirect coupling to the fixed wall 23', for example by means of which a hook end 271 of a centering pin 27 of the fixed wall 23' is engaged.

[0198] Preferably, the removable wall 24' further includes a gripping element 242 adapted to be grasped or engaged to enable movement thereof.

[0199] In a preferred embodiment, the winding tool 20 includes a plurality of angled elements 245 coupled to the removable wall 24', each sliding on an appropriately inclined guide 246. Such guides 246 extend from the removable wall towards, and preferably up to, the fixed wall 23'. The angled elements act as abutments for the wire 14 during winding and provide support, in particular, for the wire portions 14 that are not part of the straight portions 4a, 4b, i.e., the wire portions 14 that form the header of the coil 4.

[0200] In the example shown, there are at least four corner elements 245, one at each corner.

[0201] By sliding along the guide 246, the corner element 245 slides toward the center of the winding tool 20 during separation of the removable wall 24' from the engaging wall (as shown in Figures 9 and 10), removing stress from the wire 14 forming the coil 4 and allowing removal of the coil 4 without abrasion to prevent damage to the wire 14.

[0202] After the coil forming step A, the method provides an optional but preferred pressing and / or carburizing step B in which at least one straight section 4a, 4b of at least one coil 4 is pressed and subjected to a thermal carburizing treatment to compress the individual straight wire sections 1 together.

[0203] In practice, the coil 4 already formed on the winding tool 20 is moved and positioned together with the winding tool 20 into a pressing and / or carburizing device 300, such as the device shown in FIG.

[0204] In a preferred embodiment, the apparatus 300 performs both pressing and carburizing and includes a receiving seat 301 configured to receive the winding tool 20 and one or more pressing elements 30 configured to apply pressure to at least one straight portion 4a, 4b of the coil 4 wound on the winding tool 20.

[0205] Preferably, there are two pressing elements 30 positioned coaxially on opposite sides of the receiving seat, which apply pressure towards each other, preferably horizontally, to press two opposite straight portions 4a, 4b of each coil 4, respectively.

[0206] The pressing element 30 is provided with at least one heating device 31 (preferably including one or more inductors) configured to heat the straight portions 4a, 4b before, during or after said pressure and to carry out a thermal carburization treatment while the coil 4 is being wound on the winding tool 20 and thus while the arrangement of the conductive wire 14 is perfectly orderly.

[0207] The pressing element is actuated by a pressure movement system 304 which, in the illustrated embodiment, includes a piston and a coaxial spring.

[0208] In some embodiments, the heating devices 31 (best seen in Figure 28) are included in or associated with the pressing elements 30, more precisely in their heads 32, which constitute the ends of the pressing elements 30 themselves that come into contact with the straight sections 4a, 4b during pressing.

[0209] Conveniently, there are as many heating devices 31 as there are movable walls 22 .

[0210] Optionally, the pressing and / or carburizing apparatus 300 further includes a heat probe 34 and / or a pyrometer 35, preferably coupled to the pressing element 30, to enable feedback control of the thermal carburizing process by the control system of the heating element 31.

[0211] More specifically, the pressing and / or carburizing device 300 includes, in the receiving seat 301, a fixed abutment 311 on which the winding tool 20 rests. Such fixed abutment 311 has a support surface made of a heat insulating material on which the winding tool 20 rests in order to limit heat dispersion.

[0212] Preferably, the pressing and / or carburizing device 300 further comprises a press head 302 which moves orthogonally, in the illustrated example vertically, to the pressing element 30, in order to compress the winding tool (and thus the coil 4) in a direction orthogonal to the pressing element 30, bringing the movable walls 22 closer together and further compacting the straight portions 4 a, 4 b of the coil 4, determining its thickness with reference to a mechanical reference element 291 which acts as a limiting abutment. In effect, the press head 302 compresses the winding tool 20 (and thus the coil 4) against a fixed abutment 311.

[0213] Therefore, the straight portions 4a, 4b of each coil 4 are preferably subjected to pressure in two directions that are perpendicular to each other, as shown in Figures 17-19.

[0214] Advantageously, only the straight portions 4a, 4b of the coil 4 are pressed and carburized, while the non-straight portions (i.e., the portions of the coil 4 connecting the straight portions 4a, 4b, which are primarily curved and form the header of the coil 4) are left untreated so that they can be easily shaped in subsequent processes.

[0215] Once a predetermined carburizing temperature, which depends on the characteristics of the wire 14, is reached, the press element 30, and if necessary the vertical press 302, maintains the pressure for the time required for cooling, which may be assisted by a cooling device (e.g., by air, not shown), to solidify the straight sections 4a, 4b to their final dimensions.

[0216] In the example shown, the pressure applied is in the range of 140-300 bar and the temperature achieved by the heating element 31 is in the range of 170°-210° C. The duration of step B is between 15 seconds and 2 minutes.

[0217] Optionally, the pressing and / or carburizing device 300 comprises a loading slide 330 configured to bring the winding tool 20 together with the coil 4 to the receiving seat 301 and place it on the fixed abutment 311. As can be seen in Figure 17, the loading slide comprises a vertically movable platform that can slide along a horizontal track 331 and is suitable for lifting the winding tool 20.

[0218] Advantageously, the pressing and / or carburizing step B provides consistent and reproducible sizes for the straight sections 4a, 4b of the coil 4, maximizing the packing ratio and compacting them. Furthermore, because the straight sections 4a, 4b thus processed are solidified together, the arrangement of the wires 14 does not change during the entire process; the wires 14 are arranged and maintained in a neat and reproducible matrix arrangement, not grouped in a random order, but retaining the neat arrangement imparted during the initial winding.

[0219] In the example described, the straight sections 4a, 4b of the coil 4 are first pressed and then carburized, but in general the method can be carried out by either pressing or carburizing or both in the order described, or in the reverse order, or by pressing and carburizing simultaneously.

[0220] After the pressing and / or carburizing step B, the coil 4 is cooled and thereby solidified in the straight sections 4a, 4b, and the coil 4 itself is separated from the winding tool 20. By supporting the winding tool 20 by means of a hooking sleeve and / or gripping element 242 on the spindle 25, the coupling device 241 is (pneumatically) released.

[0221] The wire clamping elements 26, 261 are opened, for example by two external controllers, to release the wire 14 entering and leaving the winding. At this point, the manipulators (not shown) that guide the removable wall 24' begin to move axially away from the fixed wall 23'. During the first step of this movement, the corner elements 245 begin to slide on their respective guides 246 toward the center of the winding tool 20, relieving stress on the wire and allowing the coil 4 to be pulled out.

[0222] The manipulator guiding the removable wall 24' continues to move axially away from the fixed wall 23' in this manner until the second manipulator takes the movable wall 22 by the operating seat 249 and pulls it out of the fixed wall 23' (and out of the pins 27, 231).

[0223] At this point, the coil 4 or group of coils 4 is removed from the winding tool 20.

[0224] 22a, 22b and 22c show examples of three different loops that can be achieved with the described winding tool 20, as follows:

[0225] - In Fig. 22a, each loop S1, S2 is formed of two layers: the first layer of 5 wires and the second layer of 4 wires;

[0226] - In Fig. 22b, each loop S1', S2' is formed by two layers, each with five wires;

[0227] - In Figure 22c, each loop S1'', S2'' is formed of three layers: a first layer of 5 wires, a second layer of 4 wires and a third layer of 5 wires.

[0228] These examples are helpful in understanding that a star yoke stator made in accordance with the present invention can be distinguished from a star yoke stator made in accordance with prior art techniques by visually analyzing the placement and density of the wires within the sectors or slots.

[0229] As can be noticed, round wires tend to leave free spaces; to overcome this problem it is possible to resort to any of the solutions shown in Figures 23a, 23b, 23c.

[0230] According to this optional advantageous solution to the fill factor, during the coil manufacturing process, or more precisely during winding, a complementary conductive wire of smaller cross section 14' is added to each loop S1, S2, occupying the space left by the tangents of the larger cross section wires 14 (i.e., the free space between said larger cross section wires 14). In this way, during the winding process, each loop S1, S2 is formed by layers of wires of different cross sections, interleaved with one another, and once wound, an even greater fill factor is achieved.

[0231] 20 and 21 show a variant of the winding machine 200 and a variant of the winding tool 20, which can be used as an alternative to the first one. Instead of a separate wire guide device 206 with a wire guide tube 204 (Fig. 206), a wire orientation device 150 is used, which makes it possible to automatically manage the distance between the various levels of the incoming wire 14 by means of a control shaft.

[0232] The wire direction device 150 comprises an axial guide 151 in which a number of wire guide tubes 152 slide independently of one another in a controlled manner.

[0233] The axial guides 151 in turn slide along the vertical guides 153 so that the wire guide tube 152 is movable along at least two axes.

[0234] Each wire guide tube 152 is traversed by, and actually guides, a layer of wire 14 .

[0235] During the various winding steps, the wire guide tubes 152 can move closer together to bring the various levels of wire into contact, or they can move away from each other so that each layer enters the winding at a different time independent of the other layers.

[0236] This allows each layer to be placed on the winding tool 20 independently of the other layers, preventing them from interfering with each other.

[0237] If necessary, the wire guide tubes 152 can be moved closer together again to facilitate operations that require the wires 14 to all be close together.

[0238] Optionally, in this embodiment, winding tool 20 is rotated by a winding spindle 244' integral with a motor assembly 157 fixed to a carriage 158 movable along a track 159 (eg, a guide or track).

[0239] 20-21 and the respective winding tools 20 illustrated therein, following the coil forming step A, the method provides a pressing and / or carburizing step B, as previously described and will now be shown with reference to FIGS. 24 to 29B.

[0240] 28A and 28B comprises one or more heating elements 31, preferably induction, shaped and positioned to be inserted between the straight sections 4a, 4b of the coil and to be in contact with or adjacent to them. This operation can be performed while the coil 4 is still housed in the winding tool 20, since the straight sections 4a, 4b are left free.

[0241] These heating elements 31 therefore have a longitudinal extension substantially equal to the longitudinal extension of the straight portions 4a, 4b to be heated.

[0242] It should be noted that in the embodiment shown, the heating elements 31 form a comb of elements that are substantially parallel to one another.

[0243] In practice, a heating element 31 is inserted between the straight portions 4a, 4b of the coil for heating up to the carburizing temperature, as shown in FIG. 28B.

[0244] It is therefore possible to remove the heating element 31 and insert in its place a pressing device 300 which takes advantage of the thermal inertia of the material to press the windings.

[0245] In the embodiment shown in Figure 29, with respect to the winding tool 20 mounted on the winding machine 200 shown in Figures 20-21, the pressing device 300 comprises a plate 301 combined with a series of inclined surfaces 303 adapted to come into contact with the straight sections 4a, 4b to be pressed. The plate 301 is located opposite the straight sections 4a, 4b and is inserted into or at least mechanically coupled to a complementary counter-plate 302'.

[0246] Plate 301 is pressed against counter-plate 302' by a thrust device (not shown). The inclined surfaces 303 are configured such that movement of plate 301 towards counter-plate 302' causes compaction of the straight sections 4a, 4b of the coil by direct mechanical interaction.

[0247] Thus, the straight sections 4a, 4b of the windings are compacted to the desired dimensions using both the force of the thrust device and the appropriately constructed inclined surfaces 303.

[0248] These carburizing and pressing operations can be performed alternately or simultaneously on both sides of the winding tool 20 depending on the cycle time required for production.

[0249] Advantageously, only the straight portions 4a, 4b of the coil 4 are subjected to pressing and / or heat treatment, while the non-straight portions (i.e., the portions of the coil 4 connecting the straight portions 4a, 4b, which are primarily curved and form the header of the coil 4) are left untreated so that they can be easily shaped in subsequent processes.

[0250] After the pressing and / or carburizing step B, the coil 4 is cooled, thereby solidifying in the straight portions 4a, 4b, and the coil 4, or group of coils 4, can be removed from the winding tool 20 (one of those described herein).

[0251] Optionally, in the coil forming step A, if multiple coils 4 are manufactured in series on the same winding tool 20 and the straight portions 4a, 4b of the coils 4 are spaced apart from the straight portions of the succeeding coils 4 by a predetermined pitch distance, a step of correcting the pitch between the coils 4 is carried out before the coils 4 are inserted into the stator slots.

[0252] - taking the coils 4 from the winding tool 20 and conveying them to a pitch correction device (not shown) configured to correct the pitch distance between the straight portions 4a, 4b of the different coils 4,

[0253] After the pitch correction has been achieved, the coil 4 is removed from the pitch correction device by grippers, for example those shown in Figures 37 and 38, which are configured to keep the pitch distance between the straight portions 4a, 4b of the coil 4 unchanged. These grippers insert the coil 4 between the stator teeth in a star.

[0254] Optionally, insulating paper can be introduced into the coil 4, preferably around the straight portions 4a, 4b, to protect the coil 4 from damage in the stator slot during the pitch correction process.

[0255] The above-described forming step A of the coil 4 produces a coil 4 having straight portions 4a, 4b and a shape complementary to the shape of the stator slot 106 into which it must be inserted. Thus, the full surface area of ​​the stator slot 106 can be utilized while keeping the conductive wires 14, 14' neat and maximizing the fill factor.

[0256] 30 shows a schematic cross-sectional and plan view of an electric motor M according to the known art, including a star yoke stator S' and a rotor R rotatably and coaxially arranged within the stator S' along its axis of rotation. The stator S' is of two-part construction, i.e., it consists of an outer cylindrical body 101' (yoke) and an inner body 100' (star) made up of a pack of stacked metal laminations.

[0257] 31 shows a star 100' in perspective, with all of the stator teeth 104' extending from an inner cylindrical surface 102' defined by the pole shoes 103' and the stator teeth 104' themselves, and the stator teeth 104' extending radially outward from the inner cylindrical surface 102'. The inner cylindrical surface 102' of the star 100' is substantially continuous except for small windows or openings 105' provided to reduce the weight of the stator and minimize electromagnetic shorting phenomena. Stator slots 106' for accommodating coils of conductive wire are defined between the stator teeth 104', the inner cylindrical surface 102', and the yoke 101'.

[0258] For simplicity, only the stator slots in which the conductive wire windings 107' reside are depicted in Figure 30. A conventional motor M such as that shown in Figure 30 can be identified by the fact that the arrangement of the conductive wires in the windings 107' is not orderly or can be improved.

[0259] The object of the present invention is to provide a method and apparatus that allows for the automatic assembly of a stator with perfectly ordered coils 4 obtained as described above with reference to Figures 2 to 29, thereby maximizing the fill factor and better occupying the stator slots with complementary shapes and ordered arrangements.

[0260] 32 is a perspective view of a star 100 of a stator S1, S2 according to the invention, which differs from the star 100' of a prior art stator S' in that the stator teeth 104 are pointed at the ends 108 opposite the pole shoes 103. In practice, the ends 108 of the stator teeth 104 are pointed in order to stabilize the coupling with the yoke as will be described below.

[0261] A further difference between star 100 and star 100' lies in the shape of the stator slots: a simple visual comparison reveals that the stator slots 106' of the prior art stator S' are slice-shaped, i.e. they are widened in the outward radial direction, whereas the stator slots 106 of the stator S according to the invention are generally rectangular, thus offering a greater compatibility with the coils 4 in terms of shape.

[0262] 33 is a cross-sectional view of a stator S1 according to a first embodiment of the invention: for simplicity, individual windings made up of straight sections 4a or 4b of coils 4 are shown. The star 100 is forcefully inserted into the yoke 101', in the sense that the coupling between these elements is performed by interference. As will be explained below, the yoke 101' is interference-fit onto the star 100 after all coils 4 have been properly positioned, and the pointed ends 108 of the stator teeth 104 are inserted into corresponding longitudinal grooves 109 formed in the inner surface of the yoke 101'. The pointed shape of the stator teeth 104, together with their form-fitting into the corresponding grooves 109, ensures a mechanical seal of the stator S made of the two components 100, 101'.

[0263] Figure 34 is a perspective view of the complete stator S1 with all windings, i.e., with all of the stator slots 106 engaged by straight sections 4a or 4b of the coils 4. As can be observed, the inner surface 102 of the star 100 is continuous except for windows or openings 105. In this configuration, the stator S1 is ready to receive the rotor R to complete the electric motor.

[0264] As can be noted, the first embodiment of the stator S1 comprises a yoke 101' made in one piece from a machine cylinder.

[0265] FIG. 35 is a cross-sectional view of a stator S2 according to a second embodiment of the invention: for simplicity, an individual winding consisting of a straight section 4a or 4b of the coil 4 is shown. The star 100 is forcefully inserted into the yoke 101'', in the sense that the coupling between these elements is performed by interference. As will be explained below, the yoke 101' is constructed around the star 100 by fixing the sectors 110 of the yoke 101'' in response to the coils 4 being properly inserted into the stator slots 106, with the pointed ends 108 of the stator teeth 104 being inserted into corresponding longitudinal grooves 109 formed on the inner surface of each sector 110 of the yoke 101'. The pointed shape of the stator teeth 104, together with their form-fitting into the corresponding grooves 109, ensures the mechanical sealing of the stator S made of the two components 100, 101''.

[0266] Figure 36 is a perspective view of the complete stator S2 with all windings, i.e., with all of the stator slots 106 engaged by straight sections 4a or 4b of the coils 4. As can be observed, the inner surface 102 of the star 100 is continuous except for windows or openings 105. In this configuration, the stator S2 is ready to receive the rotor R to complete the electric motor.

[0267] As can be noted, the second embodiment of the stator S2 differs from the first S1 in that the yoke 101'' is not made in one piece but is formed by assembling sectors 110 on the outside of the star 100.

[0268] Next, a method and apparatus for manufacturing both stators S1 and S2 will be described.

[0269] 37 and 38, a gripper system used to remove the coil 4 of conductive wire 14 from the winding machine 200 or press and / or carburizer 300 and place it into the stator slot 106 of the star 100 will now be described.

[0270] Figure 37 shows a perspective view of a gripper system 400 that includes two grippers, an upper gripper 401 and a lower gripper 402, used to handle the coil 4. Figure 38 shows this system 400 in cross section (on different planes) and in elevation. The coil 4 is arranged in a vertical plane, with a straight portion 4a restrained by the upper gripper 401 and a straight portion 4b restrained by the lower gripper 402.

[0271] Grippers 401 and 402 are provided with jaws 403, the middle one floatingly mounted on pins 404 and the first and last ones fixed to pins 404, which restrain the straight sections 4a and 4b. The pins 404 are connected to pneumatic linear actuators 405, for example operated by compressed air, which are movable in two directions along a horizontal direction 406, which is transverse to the straight sections 4a and 4b of the coil 4, to open and close the jaws 403 relative to the straight sections 4a and 4b of the coil 4, respectively.

[0272] With this configuration, the grippers 401, 402 maintain the pitch distance between the first straight portion 4a and the second straight portion 4b of the coil 4 taken out from the winding tool.

[0273] The grippers 401 and 402 are further provided with an ejection element 407 movable in two directions along a vertical direction 408 perpendicular to the horizontal direction 406, in order to eject the straight sections 4a and 4b of the coil from the grippers 401 and 402 themselves. For this purpose, the ejection element 407 is fixed to a plate 409 which is movable vertically in response to a thrust exerted by an external actuator. The movement of the plate 409 is guided by a pin 410 visible in Figure 38, which moves in a hole 411.

[0274] The operation of the gripper system 400 is as follows.

[0275] Whenever a coil 4 needs to be picked up, both grippers 401 and 402 are made to engage the straight portions 4a and 4b of the coil 4 with the straight portions 4a and 4b being inserted between the jaws 403.

[0276] - the pneumatic actuator 405 is activated to grip the straight sections 4a and 4b;

[0277] At this point, the gripper system 400 can move together with the coil 4, which remains integral with the grippers 401 and 402 without the possibility of relative movement;

[0278] Whenever a straight portion 4a or a straight portion 4b of the coil 4 has to be ejected, the jaws 403 of the upper gripper 401 or the lower gripper 402, respectively, are opened and the plate 409 is pushed downwards causing the ejection element 407 to be inserted between the jaws 403, thereby ejecting the straight portion 4a or 4b.

[0279] The ejection of the straight sections 4a and 4b can and is expected to occur at different times: the upper gripper 401 and the lower gripper 402 are selectively operable.

[0280] The gripper system 400 just described can be used to manufacture both embodiments S1 and S2 of the stator according to the present invention.

[0281] 39 is a perspective view of a first apparatus 500 for manufacturing a stator S1 according to the first embodiment. The apparatus 500 comprises a spindle 501 mounted on a shaft 504 that cantilevers from a support structure 502 and is rotatable relative to the support structure 502 itself about a horizontal axis of rotation 503, with orientation defined as longitudinal, lateral or radial relative to this. The spindle 501 is rotatable and rotated by a motor housed within the support structure 502, which is not visible in the drawings.

[0282] The apparatus 500 further comprises a carriage 505 comprising a sliding block 507 and mounted on a coplanar track 506 parallel to the axis of rotation 503 of the spindle 501. With this arrangement, the carriage 505 is translatable on the sliding block 507 and on the track 506 between a first position and a second position.

[0283] in a first position, close to the support structure 502, the carriage 505 extends around the shaft 504 but does not obstruct the spindle 501, as shown in FIG. 39;

[0284] In a second position, shown in the other figures, the carriage 505 extends around the spindle 501 but does not obstruct the shaft 504, but only partially.

[0285] Longitudinal displacement of carriage 505 on track 506 is achieved by a special actuator, for example of the linear or rack type, mounted on support structure 502 or directly on carriage 505 .

[0286] The carriage 505 has a longitudinal extent, considered along the axis of rotation 503, at least equal to the longitudinal extent of the spindle 501. The carriage 505 is hollow inside: it has an inner cylindrical surface 508 coaxial with the axis of rotation 503 and therefore coaxial with the shaft 504 and the spindle 501.

[0287] The inner cylindrical surface 508 of the carriage 505 is broken by a longitudinal opening 509, i.e. an opening parallel to the generatrix of the inner cylindrical surface 508. The longitudinal opening 509 gives the carriage 505 an approximately horseshoe shape and allows the gripper system 400 to access the interior of the carriage 505 from the outside, and in particular the longitudinal opening 509 provides the possibility for the gripper system 400 to interact with the star 100 whenever the latter is fitted on the spindle 501 and the carriage 505 is in the second position, as will be explained below.

[0288] The longitudinal opening 509 has a width, measured circumferentially relative to the inner cylindrical surface 508 of the carriage 505, sufficient to allow the coil 4, and in particular the straight portions 4a and 4b of the coil 4, to be inserted from outside the carriage 505 into the volume enclosed by the inner cylindrical surface 508. In the example shown in the figure, the coil 4 comprises three straight portions 4a and three straight portions 4b, and therefore the longitudinal opening 509 has a width at least equal to the circumferential extent of three stator slots 106 of the star 100. If there were only one straight portion, the width of the longitudinal opening 509 would clearly be smaller and would be at least equal to the circumferential extent of an individual stator slot 106 of the star 100.

[0289] The apparatus 500 further comprises a closing device 510 configured to temporarily and on command close the vertical opening 509. In the example shown, the closing device 510 is mounted to the carriage 505 and moves therewith.

[0290] In the illustrated embodiment, the closure device 510 is a slide or drawer type device in which a sliding block 513 acts as an actuator and a panel 511 is mounted on tracks 512. The tracks 512 are parallel to each other and disposed obliquely relative to the axis of rotation 503, and the panel 511 is movable between a retracted position and an advanced position, tangential to the inner cylindrical surface 508 of the carriage 505. In particular,

[0291] In the retracted position shown in FIG. 39, the panel 511 does not block the longitudinal opening 509, which allows the gripper system 400 to insert the straight sections 4a, 4b of the coil 4.

[0292] In the forward position shown in the other figures, the panel 511 blocks and closes the vertical opening 509, preventing the straight sections 4a, 4b from passing through the vertical opening 509 from the inside to the outside of the carriage 505.

[0293] As shown in the other figures, the vertical dimension of the panel 511 (parallel to the axis 503) corresponds to the vertical dimension of the vertical opening 509 so as not to interfere with the header (non-linear portion) of the coil 4.

[0294] In the initial state, as shown in Figure 40, the star 100 of the stator S1 is mounted on the spindle 501, the stator teeth 104 are arranged radially outward, and the stator slots 106 are also arranged radially relative to the rotation axis 503. In the configuration shown in Figure 40, the carriage 505 is in the first position, and the closing device 510 holds the panel 511 in the retracted position and keeps the vertical opening 509 open.

[0295] Figure 41 shows a configuration subsequent in time to the configuration shown in Figure 40. Carriage 505 is pushed into a second position on track 506. Carriage 505 surrounds the spindle and star 100, and more particularly, the star 100 is positioned with minimal clearance between the outer surface of spindle 501 and the inner cylindrical surface 508 of carriage 505. The clearance is minimal and sufficient to allow spindle 501, together with star 100, to rotate without interfering with the inner cylindrical surface 508 of carriage 505.

[0296] The spindle 501 is rotated by an angle sufficient to position the stator slots 106 of the star 100 relative to the vertical openings 509, and in this position shown in Figure 41 the spindle 501 is at rest. The upwardly facing stator slots 106 are precisely accessible to the gripper system 400 through the vertical openings 509.

[0297] The rotation of the spindle 501 is intermittent and is performed to rotate the star 100 by an angle corresponding to the angular distance between the two stator slots that house the straight sections 4a, 4b of the coil. At the end of a rotation, the spindle 501 is at a standstill and remains stationary until a new rotation is required. Thus, the rotation of the spindle 501 alternates with the insertion of the straight sections 4a, 4b of the coil 4.

[0298] Figure 42 shows a configuration subsequent in time to the configuration shown in Figure 41. The gripper system 400 has been moved into the vertical opening 509. In particular, the lower gripper 402, which restrains the straight portion 4b of the coil 4, is held or abuts against the boundary of the vertical opening 509. The star 100 is in a stationary state, as are the other components of the apparatus 500. In the example shown, the coil 4 has three straight portions 4b (and corresponding three straight portions 4a), as in the configuration shown in Figures 37 and 38.

[0299] Figure 43 shows a configuration subsequent in time to that shown in Figure 42. The spindle 501 is stationary together with the star 100. The lower gripper 402 is also stationary relative to the position shown in Figure 42. The ejection element 407 of the lower gripper 402 is lowered vertically by a plate 409 (Figure 38) to eject the three straight sections 4b of the coil 4 from the gripper 402 and insert them through the vertical openings 509 into the three corresponding stator slots 106. The upper gripper 401 is lowered a height corresponding to the movement by the ejection element 407 of the lower gripper 402 to facilitate the radial movement of the coil 4.

[0300] Figure 44 shows a time-sequential configuration relative to the configuration shown in Figure 43. The spindle 501 together with the star 100 is stationary. The lower gripper 402 is moved laterally relative to the receiving plane of the coil 4, away from the carriage 505. Simultaneously with or immediately after the movement of the lower gripper 402, the closing device 510 is activated, which presses and holds the panel 511 in the advanced position, so that the vertical opening 509 is closed by the panel 511. The panel 511 acts as an external and temporary closing element for the stator slot 106. This arrangement prevents the straight portion 4b of the coil 4 from leaving the corresponding stator slot 106.

[0301] Figure 45 shows a time-sequential configuration for the configuration shown in Figure 44. Considering that the stator S1 under manufacture is of the distributed winding type, the spindle 501 is rotated (counterclockwise when viewing the figure) by an angle corresponding to one phase of the stator S1, and the upper gripper 401 simultaneously descends and reaches or abuts on the panel 511. The rotational movement of the spindle 501 around the rotation axis 503 and the vertical movement of the upper gripper 401 occur simultaneously, resulting in deformation of the coil 4.

[0302] The straight sections 4b are initially constrained in each stator slot 106 between the star 100 and the panel 511, but remain properly contained within the stator slots 106 due to the presence of the inner cylindrical surface 508 of the carriage 505 which surrounds the star 100 from the outside and rotates integrally with the star 100.

[0303] The lowering of the upper gripper 401 positions the straight portion 4a, which is still restrained by the upper gripper 401, on the panel 511 and therefore above the vertical opening 509 aligned therewith.

[0304] Figure 46 shows a time-sequential configuration relative to the configuration shown in Figure 45. The panel 511 is retracted, i.e. moved to its retracted position, so that the vertical opening 509 is available to the upper gripper 401. The upper gripper 401 is then lowered further to abut the boundary of the vertical opening 509. The straight portion 4a of the coil 4 is still restrained by the upper gripper 401.

[0305] Figure 47 shows a time-sequential configuration relative to the configuration shown in Figure 46. The ejection element 407 of the upper gripper 401 was actuated by lowering the plate 409, and the straight portions 4a of the coils 4 were each pushed into the stator slots 106 made accessible by the retraction of the panel 511 described in the previous paragraph.

[0306] Figure 48 shows a time-sequential configuration to the configuration shown in Figure 47. The gripper system 400 is moved away from the device 500 and the panel 511 is pushed to an advanced position again closing the vertical opening 509 and preventing the straight portions 4a of the coil 4 from protruding from the stator slots 106. In this configuration, the coil 4 is fully inserted into the star 100 and consists of three straight portions 4b and three straight portions 4a rotated by a predetermined angle corresponding to the electrical phases. The spindle 501 is stationary.

[0307] Figure 49 shows a time-sequential configuration to that shown in Figure 48. Gripper system 400 is moved to panel 511 with new coil 4 fixed to grippers 401 and 402.

[0308] Figure 50 shows a time-sequential configuration relative to the configuration shown in Figure 49. The spindle 501 has been rotated to a position corresponding to the longitudinal opening 509 of the stator slot 106 of the star 100 corresponding to the new electrical phase. The panel 511 is stationary in the advanced position and the gripper system 400 is also stationary.

[0309] Figure 51 shows a time-sequential configuration to that shown in Figure 50. The spindle 501 was stationary from the previous configuration in Figure 50. The panel 511 has been moved to a retracted position, leaving the vertical opening 509 open and accessible to the lower gripper 402, as well as the three stator slots 106 of the three stars 100 into which the straight sections 4b of the new coils 4 will be inserted.

[0310] The steps shown in FIGS. 44-50 are repeated for the new coil 4, resulting in two coils 4 being positioned on the star 100.

[0311] Figure 52 shows a time-sequential configuration for the first and second coils 4 in a stowed state, with the third coil 4 in an operable state.

[0312] Figure 53 shows a time-sequential configuration to the configuration shown in Figure 52. Three coils 4 are already housed on the star 100 and the fourth coil 4 is ready to be moved.

[0313] Figure 54 shows a time-sequential configuration to that shown in Figure 53. Four coils 4 are already fitted onto the star 100, and the fifth coil 4 is ready to be manipulated to insert the straight portions 4a and 4b into the stator slots 106.

[0314] Figure 55 shows a time-sequential configuration to that shown in Figure 54. Five coils 4 are already fitted onto the star 100, and the sixth coil 4 is ready to be manipulated to insert the straight portions 4a and 4b into the stator slots 106.

[0315] Figure 56 shows a time-sequential configuration to that shown in Figure 55. Six coils 4 are already fitted onto the star 100, and the seventh coil 4 is ready to be manipulated to insert the straight portions 4a and 4b into the stator slots 106.

[0316] Figure 57 shows a time-sequential configuration to that shown in Figure 56. Eight coils 4 are already installed on the star 100, and the ninth coil 4 is ready to be manipulated to insert the straight portions 4a and 4b into the stator slots 106.

[0317] 58-61 show the final steps in the method of manufacturing stator S1.

[0318] In particular, Figure 58 shows the device 500 with the winding on the star 100 completed. Nine coils 4 are fixed to the star 100. The panel 511 is moved to an advanced position to close the vertical opening 509.

[0319] The integrally formed yoke 101' is moved onto the carriage 505. The yoke 101' is cylindrical, and its inner surface is formed with longitudinal grooves 109 into which the tips 108 of the stator teeth 104 of the star 100 are inserted.

[0320] The yoke 101' is shown in abutment against the carriage 505 in Figure 59. The yoke 101' is supported by suitable means (not shown) coaxially with the axis of rotation 503 of the spindle 501. During this process, the spindle 501 remains stationary and the panel 511 is also stationary in the advanced position. The yoke 101' and star 100 are angularly aligned so that the tips 108 of the stator teeth 104 coincide with the longitudinal grooves 109 of the yoke 101'.

[0321] Figure 60 shows a subsequent configuration in time in which the carriage 505 is retracted and displaced from a previously stationary second position to a first position in which it does not obstruct the star 100 and the semi-finished product with its windings. At the same time as the carriage 505 is displaced on the track 506, the yoke 101' moves forward and follows the carriage 505 by fitting onto the wound star 100. The yoke 101' is force-fit onto the star 100, the coupling being a force fit with interference.

[0322] Figure 61 shows the final step: the stator S1 is completed and extracted from the spindle 501. The panel 511 of the closing device 510 is retracted to open the vertical opening 509. The device 500 is now ready to start a new work cycle to manufacture another stator S1.

[0323] The spindle 501 is preferably a variable geometry spindle whose diameter can be varied to secure the star 100 and to allow the stator S1 to be extracted.

[0324] In summary, the star 100 is mounted on the spindle 501 and the carriage 505 is moved to a second position surrounding the star 100, while leaving one or more stator slots 106 accessible. The closing device 510 is operable to close the stator slots that remain accessible by the carriage 505. Insertion of the straight sections 4a, 4b of the coils 4 according to the desired electrical arrangement is achieved by synchronizing the movement of the gripper system 400 with the rotation of the spindle 501 and the movement of the closing device 510. After all the coils 4 have been accommodated, the yoke 101' is mounted on the star 100, completing the stator S1.

[0325] 62-91, a method and apparatus 600 for realizing a second embodiment of the stator S2 will be described. The gripper system 400 is the same as that described above with respect to the first embodiment S1.

[0326] Figure 62 is a perspective view of apparatus 600, consisting of a support structure 602 cantilevering a spindle 601 on a shaft 604. Shaft 604 and spindle 601 are rotatable about an axis of rotation 603, with an axial, lateral or radial orientation defined about this axis. Rotation is imparted by an actuator (not shown) inside support structure 602. Rotating spindle 601 serves to support star 100 during the insertion of straight sections 4a and 4b of coils 4 into stator slots 106.

[0327] The apparatus 600 further comprises a system 610 for manipulating the sectors 110 of the yoke 101'' (shown in Figures 35, 36, 63 and 75), the operation of which makes use of a plurality of fork-shaped elements 611. All fork-shaped elements 611 (Figure 66) inserted into corresponding radial seats 605 of the spindle 601 are shown in Figure 62, however this is only a preview of a temporary configuration, which will be explained in more detail below.

[0328] The apparatus 600 further comprises a system 700 of jaws 701 which are movable towards and away from the winding spindle 601 to restrain the sectors 110 of the yoke 101'' and allow removal of the completed stator S2.

[0329] FIG. 63 shows a perspective view of the device 600 and a partial axisymmetric cross-sectional view of the spindle 601 with the stator S2 completed. This view is useful for understanding the operation of the fork-shaped elements 611. Two fork-shaped elements 611 are used for each sector 110 of each yoke 101′, located at the axial ends of the sector 110. The radially outer end 611′ of each fork-shaped element 611 has teeth that form undercuts with the edges 110′ (FIG. 65) of each sector 110 of the yoke 101″, to restrain the sector on the spindle 601 during assembly of the stator S2. The opposite end of the fork-shaped element 611 also has teeth 611″ intended to engage with corresponding teeth of levers 612 present on the spindle 601. In practice, the spindle 601 is provided with the same number of levers 612 as there are fork-shaped elements 611 to be engaged. Lever 612 extends radially from the hub of spindle 601 and is hinged on a pin 613 circumferentially oriented on spindle 601. When engaged by end teeth 611" of fork-shaped element 611, lever 612 is counter-forced by spring 613' so that it first retracts and then snaps into a restraining position, with teeth 612' of lever 612 engaging teeth 611" of fork-shaped element 611. To achieve the opposite effect, i.e., disengagement of fork-shaped element 611, it is sufficient to apply a thrust to lever 612 from the outside along rotation axis 603, causing lever 612 to rotate and disengage teeth 611".

[0330] The reason that the element 611 is fork-shaped is that the legs 614 extend from opposite sides of the straight portions 4 a, 4 b of the coil 4 when these straight portions are inserted into the stator slot 106. In other words, the fork-shaped element 611 straddles the straight portions 4 a, 4 b of the coil 4 to engage with the lever 612 of the spindle 601.

[0331] FIG. 64 is a perspective view of a system 610 for manipulating sectors 110 of a yoke 101″, and FIG. 65 is a longitudinal section and an elevation view of the system 610 itself. In these figures, the system 610 is shown clamping a sector 110 of a yoke 101″. In practice, the system 610 comprises a gripper 620 with two jaws 621, 622 that can move towards and away from each other to clamp and release the individual sectors 110 of the yoke 101″, respectively. The operation of the jaws 621, 622 can be electric or pneumatic.

[0332] As can be seen in Figures 64 and 65, each sector 110 of the yoke 101'' is moved by the system 610 with the fork-shaped elements 611 already attached, i.e., pre-positioned so that the upper teeth 611' of the fork-shaped elements 611 engage with the upper boundary 110' of the sector 110 of the yoke 101'' and the legs 614 of each fork-shaped element 611 extend cantilevered downwards, making the teeth 611'' accessible.

[0333] First, as shown in Figure 66, the star 100 of the stator S2 is moved towards the spindle 601 along the axis of rotation 603, with the stator teeth 104 facing radially outwards and the stator slots 106 positioned radially relative to the axis of rotation 603. The spindle 601 is stationary and radial seats 605 are visible on it, into which the fork-shaped elements 611 are precisely radially inserted. The gripper system 400 prepares the coil 4. The manipulating system 610 also prepares the sector 110 of the yoke 101'' and the two corresponding fork-shaped elements 611 pre-positioned on the sector 110.

[0334] Figure 67 shows a time-sequential configuration to that shown in Figure 66. The star 100 has been mounted on the spindle 601. It should be noted that the radial seat 605 remains at least partially uncovered, i.e. unobstructed by the star 100, due to the insertion of the fork-shaped element 611.

[0335] Figure 68 shows a time-sequential configuration to that shown in Figure 67. Gripper system 400 is positioned next to star 100, which is held stationary by spindle 601. Lower gripper 402 has lowered to the level of, and possibly abutting, tips 108 (Figure 32) of stator teeth 104. In this position, straight sections 4b of coils 4 are ready for insertion into radially arranged stator slots 106.

[0336] Figure 69 shows a time-sequential configuration relative to the configuration shown in Figure 68. The lower gripper 402 was actuated to push the straight portions 4b of the coils 4 into the respective stator slots 106 of the star 100. In particular, the vertically movable plate 409 was lowered, which lowered the ejection element 407. At the same time, the upper gripper 401 was also lowered by a length corresponding to the travel distance of the ejection element 407, in order not to deform the coils 4. The spindle 601 and the star 100 remain stationary.

[0337] Figure 70 shows a time-sequential configuration to that shown in Figure 69. The spindle 601 and star 100 continue to remain stationary. The upper gripper 401 retracts, maintaining the same height, to make room for the handling system 610, which must move above the lower gripper 402. The displacement of the upper gripper causes deformation of the header, i.e., non-linear portion 4c, of the coil 4, while the linear portion 4b remains undeformed within the inserted stator slot 106, and the linear portion 4a remains undeformed between the jaws of the upper gripper 401. The exit of the linear portion 4b of the coil 4 from the stator slot 106 is prevented by the same lower gripper 402, which temporarily closes the stator slot 106.

[0338] Figure 71 shows a time-sequential configuration to that shown in Figure 70. Spindle 601 and star 100 continue to remain stationary. Upper gripper 401 remains stationary relative to the retracted position described with reference to Figure 70. Lower gripper 402 also retracts and is moved past coil 4 and underneath upper gripper 401. In this configuration, there is no risk of straight portion 4b of coil 4 coming out of stator slot 106, as coil 4 has already been deformed at non-straight portion 4c and is not under stress returning straight portion 4b to straight portion 4a.

[0339] Figure 72 shows a time-sequential configuration relative to that shown in Figure 71. Spindle 601 and star 100 continue to remain stationary. Grippers 401 and 402 also remain stationary relative to the positions shown in Figure 71. At this point, manipulation system 610 moves over stator slot 106 of star 100 which houses straight section 4b of coil 4.

[0340] Figure 73 shows a time-sequential configuration relative to the configuration shown in Figure 72. The spindle 601 and the star 100 continue to remain stationary. The operating system 610, pre-aligned with the stator slots 106 into which the straight portions 4b of the coils 4 have been inserted, is lowered until the sectors 110 of the yoke 101'' abut against the tips 108 of the stator teeth 104 of those stator slots 106. At the same time, the fork-shaped elements 611 are inserted into the radial seats 605 (Figures 62-65), which causes the levers 612 to snap. More specifically, the legs 614 of the fork-shaped elements 611 are inserted into the respective radial seats 605 present on the spindle 601, causing the lower teeth 611'' to engage with the teeth 612' of the levers 612 present on the spindle 601 (Figure 63), which causes the levers 612 to swing around the respective pins 613.

[0341] Figure 74 shows a time-sequential configuration relative to the configuration shown in Figure 73. The spindle 601 and the star 100 continue to remain stationary. The manipulating system 610 remains stationary, having been lowered until the sectors 110 of the yoke 101'' abut against the tips 108 of the stator teeth 104 of the stator slots 106 that house the straight portions 4b of the coils 4. The sectors 110 of the yoke 101'' are held on the spindle 601 by the fork-shaped elements 611. The jaws 621 and 622 of the manipulating system 610 open, releasing the sectors 110 of the yoke 101'', which are no longer held by the system 610 and remain hooked to the star 100 by the fork-shaped elements 611.

[0342] Figure 75 shows a time-sequential configuration to that shown in Figure 74. The spindle 601 and star 100 continue to remain stationary. The manipulation system 610, previously released from the sector 110 of the yoke 101'', is moved away from the gripper system 400 and the spindle 601. The upper gripper 401 of the gripper system 400 continues to grip the straight portion 4a of the coil 4, while the straight portion 4b is now securely enclosed in the stator slot 106 closed by the sector 110 of the yoke 101''.

[0343] Figure 76 shows a time-sequential configuration relative to the configuration shown in Figure 75. The spindle 601 rotates (counterclockwise in the figure), thereby rotating the star 100 through an angle corresponding to the electrical phase of the stator S2. At the same time, the upper gripper 401 is lowered to facilitate the deformation of the non-linear portion 4c of the coil 4, and the manipulation system 610 grips a new sector 110 of the yoke 101'' with each pre-positioned fork-shaped element 611. In particular, the upper gripper 401 reaches or abuts against the tips 108 of the stator teeth 104, ready to release the linear portion 4a of the coil 4.

[0344] Thus, the rotation of the spindle 601 is intermittent and alternates with the insertion movement of the gripper 401 .

[0345] Figure 77 shows a time-sequential configuration relative to the configuration shown in Figure 76. The spindle 601 and star 100 remain stationary relative to their pre-assumed positions (Figure 76). The plate 409 of the upper gripper 401 is lowered, which causes the pusher element 407 to lower and the straight portions 4a of the coils 4 to insert into the corresponding stator slots 106.

[0346] Figure 78 shows a time-sequential configuration relative to the configuration shown in Figure 77. The spindle 601 and star 100 remain stationary relative to their pre-assumed positions (Figure 76). The gripper system 400 is moved away from the spindle 601 and the grippers of the upper 401 and lower 402 parts are opened, ready to take a new coil of the winding tool 20. The manipulating system 610 moves a new sector 110 of the yoke 101'' above the stator slot 106 that accommodates the straight portion 4a of the coil 4.

[0347] Figure 79 shows a time-sequential configuration relative to the configuration shown in Figure 78. The spindle 601 and star 100 remain stationary relative to their pre-assumed positions (Figure 77). The manipulating system 610 places a new sector 110 of the yoke 101'' on the stator slot 106 that accommodates the straight section 4a of the coil 4 and pushes the fork-shaped element 611 into engagement with the lever 612 of the spindle 601, restraining the sector 110 on the star 100.

[0348] Figure 80 shows a time-sequential configuration relative to the configuration shown in Figure 79. The spindle 601 and star 100 remain stationary relative to their pre-assumed positions (Figure 79). The manipulation system 610 releases a new sector 110 of the yoke 101'' and moves away to take another sector 110 of the same yoke 101''. The coil 4 is now properly inserted into the star 100. The straight portions 4a and 4b are constrained in their respective stator slots 106 by the two sectors 110 and four fork-shaped elements 611 of the yoke 101''.

[0349] Figure 81 shows a time-sequential configuration to that shown in Figure 80. The spindle 601 and star 100 rotate (counterclockwise) an angle sufficient to bring the gripper system 400 into another stator slot 106 to accommodate the straight section 4b of the new coil 4, and then stop again and remain stationary.

[0350] At this point, the procedure described in the previous figure is repeated to complete the winding of the star 100.

[0351] FIG. 82 shows a time-sequential configuration relative to the configuration shown in FIG. 81, showing two coils 4 arranged on a star 100 and four sectors 110 of a yoke 101″ fixed to a spindle 601 by levers 612.

[0352] FIG. 83 shows a time-sequential configuration relative to the configuration shown in FIG. 82, showing three coils 4 arranged on a star 100 and six sectors 110 of a yoke 101″ fixed to a spindle 601 by levers 612.

[0353] FIG. 84 shows a time-sequential configuration relative to the configuration shown in FIG. 83, showing four coils 4 arranged on a star 100 and eight sectors 110 of a yoke 101″ fixed to a spindle 601 by levers 612.

[0354] The insertion of each new coil is based on the electrical configuration and is performed according to the step of the stator S2. The angular deviation between the straight sections 4a and 4b of all coils is electronically compensated.

[0355] FIG. 86 shows a time-sequential configuration relative to the configuration shown in FIG. 85, showing five coils 4 arranged on a star 100 and ten sectors 110 of a yoke 101″ fixed to a spindle 601.

[0356] Figure 87 shows the winding S2 completed with all windings. In the example shown, nine coils 4, each with three straight sections 4a and three straight sections 4b, and 18 sectors 110 of the yoke 101'' were used. Obviously, each sector 110 occupies an angle equal to the central angle of 20°. All sectors 110 are fixed to the spindle 601 by fork-shaped elements 611, completing the yoke 101''. Now, the stator S2 only needs to be withdrawn from the spindle 601.

[0357] Figure 88 shows the start of removal. The spindle 601 and stator S2 are stationary. The jaw system 700 is actuated and jaws 701 move in to grip the stator S2.

[0358] FIG. 89 shows the jaws 701 closed on the yoke 101'' of the stator S2, with the spindle 601 stationary.

[0359] At this point, as shown in Figure 90, the fork-shaped element 611 which previously restrained the sector 110 on the spindle 601 is removed. Removal is achieved by applying a thrust to the lever 612 in the axial direction by suitable means (not shown) to counter the thrust of the spring 613' shown in Figure 63.

[0360] Figure 91 shows the final step of extracting stator S2 from spindle 601, ready to begin a new cycle to manufacture a new stator S2. Yoke 101'' remains closed within jaws 701 until yoke 101'' is wrapped by suitable means, such as metal straps. At this point, jaws 701 open to release stator S2.

[0361] FIG. 92 is a schematic diagram (stator portion in cross section) of a winding layout for a star yoke stator according to the prior art, similar to the stator of motor M shown in FIG. 30. As can be seen, the windings 107' inserted into the stator slots 106' are not orderly: the conductive wires 14 are randomly arranged. The table in FIG. 92 shows, for example, a diameter of the conductive wires 14 of 9.9 mm, the number of arranged parallel wires, the number of loops, the area, the thickness of the insulating paper, and the area of ​​the stator slots 106' of 117.340 mm. 2 The technical characteristics of the winding are detailed by setting

[0362] This configuration, currently one of the most common, reaches a fill factor of approximately 39% (bare wire / slot).

[0363] FIG. 93 is a diagram of five possible layouts for the windings of a star yoke stator S1 in accordance with the present invention, including cross-sectional views of stator slots 106, and also includes a table showing the technical requirements for the windings of each layout.

[0364] The difference with the known art arrangement shown in FIG. 92 is immediately apparent: the method and apparatus according to the invention allows the conductive wire (main) 14 and possibly the conductive wire (complementary) 14' of smaller diameter to be arranged in an orderly manner according to the desired layout, forming an unalterable winding 107 by carburizing and pressing the coil 4 as described above.

[0365] The table lists the diameter and other parameters of the conductive wires 14, 14' for each of the five layouts. The conductive wires 14, 14' were pressed and carburized as described with reference to Figures 1-29. The insulating paper placed between the windings 107 and the stator slots 106 had a thickness of 0.2 mm.

[0366] As can be seen by reading the last line below, the fill factor is always above 64% for all layouts, reaching almost 71% for the third winding layout, which has 87 conductive wires 14 with a diameter of 0.9 mm per layer, for a total of 8 loops, and 2 complementary wires 14' with a diameter of 0.45 mm.

[0367] In the example shown, rectangular stator slots 106 were considered. Dimensions are given for each stator slot 106 in different layouts.

[0368] FIG. 94 is a cross-sectional view of a portion of a hypothetical star-yoke stator, comparing a stator slot 106' (left) filled in a conventional manner with an identical stator slot 106 (right) filled in a manner according to the present invention. Slots 106' and 106 are identical and are defined by the same star and the same yoke. Although hypothetical, this view clearly illustrates the difference between the known solution and the present invention with respect to the placement of the conductive wires 14, and makes clear that stators S1, S2 manufactured according to the claimed method are practically distinguishable from stators manufactured according to the prior art. Area (cross-section) 117.34 mm 2 The slot contains the following:

[0369] In the left slot 106', 8 loops of winding formed by 9 parallel copper wires 14 with a diameter of 0.9 mm (resin coated wire outer diameter 0.987 mm) for a total of 72 wires per slot 106'. With this configuration, a fill factor of approximately 39% is achieved.

[0370] In the right slot 106, 8 loops of winding formed by 78 parallel copper wires 14 with a diameter of 0.9 mm (resin coated wire outer diameter 0.987 mm) for a total of 120 wires per slot 106. With this configuration, a fill factor of approximately 68.6% is achieved.

[0371] In the left slot 106', the conductive wires 14 are grouped, but in a chaotic and unorganized arrangement. Conversely, in the right slot 106, the conductive wires 14 are grouped in an organized arrangement, the same arrangement achieved and maintained in the straight sections 4a and 4b of the coil 4 used to make the winding that is the subject of this invention. The organized arrangement of the conductive wires 14 in the right slot 106 is equivalent to that seen in FIG. 93. For equivalent diameters of the conductive wires 14 and stator slot shapes, the fill factor in the left slot 106' is approximately 39%, while the fill factor in the right slot 106 is approximately 68.6%, i.e., significantly greater (more than 20%).

[0372] This description provides sufficient information to distinguish stators directly formed by the method of the present invention from stators formed by known techniques. Indeed, the packing factor is clearly greater, and in particular, in stators S1 and S2 according to the present invention, the conductive wires 14 are arranged in a systematic manner in the slots 106 between the teeth 104, a manner not seen in known techniques. In particular, by observing Figures 93-94, it can be seen that the conductive wires 14 are arranged in multiple loops, each consisting of a fixed number of wires (6, 7, 8, etc.), forming an unalterable, systematic matrix layout. Thus, stators S1 and S2 can be distinguished from other known stators simply by observing the number and arrangement of conductive wires in the slots between the stator teeth.

[0373] FIG. 95 shows the leakage current (ordinate) in the stator windings of a motor made with a star yoke stator S' according to the prior art and a motor made with a star yoke stator S1 according to the invention against the number of revolutions (abscissa), other technical characteristics being equal.

[0374] The comparison was carried out under equal conditions: same motor power / size, same standard rotor, same winding stack height, etc.

[0375] At 3400 revolutions per minute (RPM), which is the rated speed here, the conventional motor experiences a stator winding leakage current equivalent to 4270.205 W, while the motor with the stator S1 according to the present invention experiences a leakage current equivalent to 3016.136 W. This is an improvement of approximately 29.7%.

[0376] At 10,000 revolutions per minute (RPM), the maximum speed considered here, the conventional motor experiences a stator winding leakage current equivalent to 7155.682 W, while the motor with the stator S1 according to the present invention experiences a leakage current equivalent to 5716.293 W. This represents an improvement of approximately 20.1%.

[0377] FIG. 96 is a plot of efficiency (ordinate) versus speed (abscissa) for a motor made with a star yoke stator according to the prior art and a motor made with a star yoke stator according to the present invention, all things being equal.

[0378] The comparison was carried out under the same conditions: same motor power / size, same slot area, same standard rotor, same winding stack height, etc.

[0379] At 3250 revolutions per minute (RPM), considered here to be the rated speed, the conventional motor has an efficiency of 95.3%, while the motor with the stator S1 according to the present invention has an efficiency of 96.4%, an improvement of approximately 1.1%.

[0380] At 7000 revolutions per minute (RPM), the conventional motor has an efficiency of 94.2% and the motor with the stator S1 according to the present invention has an efficiency of 95.2%, which is an improvement of about 1.1%.

[0381] At 10,000 revolutions per minute (RPM), the highest speed considered here, the conventional motor has an efficiency of 92.5% and the motor with stator S1 has an efficiency of 93.9%, an improvement of approximately 1.45%.

[0382] FIG. 97 is a plot of power (ordinate) versus rotational speed (abscissa) for a motor made with a star yoke stator according to the prior art and a motor made with a star yoke stator according to the present invention, all things being equal.

[0383] The comparison was carried out under the same conditions: same motor power / size, same slot area, same standard rotor, same winding stack height, etc.

[0384] As can be seen, the motor of the present invention made with stator S1 produces a much greater power output than a motor based on a standard insertion of windings. Observing Figure 97, the difference is already noticeable at 1750 rpm and becomes apparent above 3400 rpm. The comparison table below shows a quantitative comparison. (Table 1) JPEG2026508392000002.jpg84159

[0385] Ultimately, therefore, the apparatus and method according to the present invention makes it possible to produce stators, and therefore electric motors, having significantly better performance for a given size and substantial shape than can be achieved with conventional winding techniques.

Claims

1. A method for manufacturing a two-component stator (S1, S2) having distributed windings called a star yoke stator The stators (S1, S2) are an outer body (101', 101'') called the yoke; a body (100) within said yoke (101', 101''), called a star, having an inner cylindrical surface (102) defining a volume for accommodating said rotor (R) of an electric motor, and a plurality of radial stator teeth (104) projecting from said cylindrical surface (102) towards said yoke (101', 101'') and between which are stator slots (106) intended to accommodate windings (107) of conducting wires (14, 14'), The method comprises: a coil (4) manufacturing step (A) of conductive wires (14, 14') in which one or more conductive wires (14, 14') are wound on a winding tool (20) to form at least one coil (4) comprising straight portions (4a, 4b) of a plurality of individual conductive wires (14, 14') and comprising at least one straight portion suitable for insertion into one of said stator slots (106); - a step (C) of supporting said star (100) on a rotation axis (503, 603) with at least one first stator slot (106) accessible to the manipulator (400) of said coil (4); - step (D) of inserting, by means of said manipulator (400), a first straight portion (4b) of said coil (4) into at least one first stator slot (106) and constraining a second straight portion (4a) of said coil (4); a step (E) of rotating said star (100) by an angle around said axis of rotation (503, 603), thereby deforming said coils (4) in said portion (4c) comprised between said straight portions (4a, 4b) and making at least one second stator slot (106) accessible to said manipulator (400); - a step (F) of inserting, by means of said manipulator (400), a second straight portion (4a) of said coil (4) into said at least one second stator slot (106); - step (G) of repeating steps D, E and F until the winding of said star (100) is completed, i.e. until a straight section (4a, 4b) of the coil (4) has been inserted into each stator slot (106); - a step (H) of restraining said star (100) to said yoke (101', 101''). method.

2. 2. The method of claim 1, wherein during step E, the star (100) is rotated by an angle corresponding to the angle between the first stator slot (106) and the second stator slot (106), which slots may be adjacent or non-adjacent, and during steps D and F, the star (100) is held stationary, and step E alternates with steps D and F.

3. 3. A method according to claim 1 or claim 2, wherein in step E, the star (100) is rotated about the axis of rotation (503, 603) by an angle corresponding to the electrical phase of the completed stator (S1, S2).

4. 10. The method according to any one of the preceding claims, characterized by a pressing and / or carburizing step (B) before step D, in which the straight sections (4a, 4b) of the at least one coil (4) are subjected to a pressing or a thermal carburizing treatment, or both pressing and a thermal carburizing treatment simultaneously in any desired order, to compact the individual straight wire sections (14, 14').

5. 5. The method according to claim 4, wherein the pressing and / or carburizing step (B) comprises pressing the straight portions (4a, 4b) of the coil (4) with one or more pressing elements (30) and heating the straight portions (4a, 4b) by one or more heating devices (31) included in or associated with the pressing elements (30) while the coil (4) is being wound on the winding tool (20).

6. 6. The method according to claim 4 or claim 5, wherein in the pressing and / or carburizing step (B), the thermal carburizing is carried out by inserting one or more heating elements (31) between the straight portions (4a, 4b) of the coil (4) while the coil (4) is housed in a winding tool (20) and heating the coil to a predetermined carburizing temperature.

7. 7. The method according to one or more of the preceding claims 4 to 6, wherein in the pressing and / or carburizing step (B), the straight portions (4a, 4b) are pressed by a pressing device (300) inserted between the straight portions (4a, 4b) while the coil (4) is housed in a winding tool (20).

8. 10. The method according to claim 1, wherein in the coil manufacturing step (A), a complementary wire (14') having a cross section smaller than the cross section of the conductive wire (14) is added to the one or more conductive wires (14), the complementary wire (14') occupying the free space between the conductive wires (14).

9. The method further includes insulating the conductive wire (14), the electrically insulating layer comprising: - if provided, applied to at least said straight sections (4a, 4b) of said coil (4) after the pressing and / or carburizing step (B), or - applied between the stator teeth (104) before step D of inserting the straight sections (4a, 4b) of the coil (4); 10. A method according to one or more of the preceding claims.

10. 10. The method according to one or more of the preceding claims, wherein in the coil manufacturing step (A), the straight portions (4a, 4b) of the coil (4) are spaced apart from the straight portions (4a, 4b) of the succeeding coil (4) by a predetermined pitch distance, and a series of multiple coils (4) are manufactured on the same winding tool (20).

11. - before step E and during insertion step D, the first straight portions (4b) of said series of coils (4) are simultaneously inserted into the corresponding stator slots (106) of said star (100); After step E, second straight portions (4a) of the series of coils (4) are simultaneously inserted into corresponding stator slots (106) of the star (100) so that corresponding windings (117) are distributed among a plurality of stator slots (106); The method of claim 10.

12. Between steps D and E, and between steps F and G, (D', F'), wherein the stator slots (106) together with the respective straight portions (4a, 4b) of the coils (4) contained therein are temporarily closed by a closure device (510) for the stator slots (106), the device being movable between a retracted position in which the stator slots (106) are radially open and accessible to the manipulator (400), and an advanced position in which the stator slots (106) are radially closed to prevent the straight portions (4a, 4b) of the coils (4) from exiting.

10. A method according to one or more of the preceding claims.

13. 10. The method according to one or more of the preceding claims, wherein during the insertion step D, the first straight portion (4b) of each coil (4) is kept flush with the second straight portion (4a) of the manipulator (400).

14. 10. The method of claim 1, wherein steps C and G are performed within a cylindrical surface (508) of a winding device (500) supporting the star (100) on a spindle (501), the cylindrical surface (508) having longitudinal openings (509) providing radial access to the first stator slots (106) of the star (100), such that only the stator slots (106) into which the straight sections (4a, 4b) of the coils (4) are to be inserted at any given time are accessible from the outside, while the rest of the star (100) is confined between the spindle (501) and the cylindrical surface (508).

15. 15. The method according to claim 14, wherein steps D and F are performed by locating the stator slots (106) intended to accommodate the straight sections (4b, 4a) of the coils (4) in the longitudinal openings (509) by rotating the star (100), and keeping the star stationary during the insertion of the straight sections (4b, 4a).

16. 10. The method according to one or more of the preceding claims, wherein the yoke (101') is made in one piece and step H is performed by inserting the star (100) together with the windings (107) into the yoke (101').

17. 12. The method according to claim 1, wherein the yoke (101'') is made as a set of sectors (110), and step H is realized by constraining the sectors (110) in the stator slots (106) into which the straight portions (4b, 4a) of the coils (4) are inserted, by an operating system (610) for operating the sectors (110) of the yoke (101'') sequentially between steps E and F and between steps F and G, thereby achieving external closure of the stator slots (106).

18. 18. The method of claim 17, wherein step H is performed by temporarily constraining the sectors (110) of the yoke (101'') to both the star (110) and the spindle (601) on which the star (110) is supported by removable fastening elements (611), and the finished yoke (101'') is held together by a jaw system (700).

19. A two-component stator (S1, S2), called a star yoke stator, achieved directly by the method according to any one of the preceding claims.

20. An electric motor comprising a two-component stator (S1, S2), called a star yoke stator, directly achieved by the method according to any one of the preceding claims.

21. An apparatus (500, 600) for manufacturing a star yoke stator (S1, S2), comprising: The stators (S1, S2) are an outer body (101', 101'') called the yoke; a body (100) within said yoke (101', 101''), called a star, having an inner cylindrical surface (102) defining a volume for accommodating said rotor (R) of an electric motor, and a plurality of radial stator teeth (104) projecting from said cylindrical surface (102) towards said yoke (101', 101'') and between which are stator slots (106) intended to accommodate windings (107) of conducting wires (14, 14'), The device (500, 600) at least one winding tool (20) configured to perform step A, in which one or more conductive wires (14, 14') are wound on the winding tool (20) to form a coil (4) comprising straight portions (4a, 4b) of a plurality of individual conductive wires (14, 14'), the coil comprising at least one straight portion suitable for insertion into one of said stator slots (106); a spindle (501, 601) rotatable about an axis of rotation (503, 603) and lockable in several angular positions, said spindle (501, 601) comprising: - supporting said star (100) with at least one first stator slot (106) of said star (100) accessible to the manipulators (400) of said coils (4); and - a spindle (501, 601) configured to rotate (E) the star (100) through an angle that makes at least one second stator slot (106) accessible to the manipulator (400) of said coil (4), and to deform said coil (4) in the portion (4c) included between the straight portions (4a, 4b) during step E; a manipulator (400) for said coil (4) configured to perform step D by inserting a first straight portion (4b) of said coil (4) into a corresponding stator slot (106) and constraining a second straight portion (4a) of the same coil (4), and to perform step F by inserting the second straight portion (4a) of said coil (4) into a corresponding stator slot (106), - characterized in that said spindle is subject to intermittent rotation alternating with the movements of a manipulator (400) for inserting the straight sections (4a, 4b) of said coil (4). Device.

22. 22. The apparatus (500, 600) of claim 21, wherein the winding tool (20) includes a support frame (21) supporting a series of angular elements (23), each series arranged substantially along an edge of an ideal parallelepiped, the angular elements (23) of each series spaced apart from one another to define a corresponding series of winding chambers (24) for accommodating the conductive wire (14) forming the coil (4).

23. 23. The device (500, 600) according to claim 21 or claim 22, comprising a wire guiding device (150) including an axial guide (151) having a plurality of wire guide tubes (152) that slide in a controlled and independent manner from one another, each wire guide tube (152) being crossed and guided by one or more layers of wires (14, 14') intended to form layers of loops.

24. 10. An apparatus (500, 600) according to any one of the preceding claims, comprising a pressing device (300) for pressing straight sections (4a, 4b) of a coil (4), comprising a plate (301) to which is attached a series of inclined surfaces (303) adapted to come into contact with the straight sections (4a, 4b) to be pressed.

25. 10. An apparatus (500, 600) according to any one of the preceding claims, comprising a heating device (30') for carrying out a thermal carburization treatment of straight sections (4a, 4b) of a coil (4), comprising one or more heating elements (31), preferably by induction, shaped and arranged to be inserted between said straight sections (4a, 4b) of the coil (4).

26. 10. The apparatus (500, 600) of any one of the preceding claims, wherein the manipulator (400) of the coil (4) comprises a first gripper (401) or upper gripper and a second gripper (402) or lower gripper, the lower gripper (402) configured to take the first straight portions (4b) of the coil (4) from the winding tool (20), restrain them and push them into a first stator slot (106), and the upper gripper (401) configured to take the second straight portions (4a) of the coil (4) from the winding tool (20), restrain them and push them into a second stator slot (106).

27. The upper gripper (401) and the lower gripper (402) - an initial coplanar position in which the coil (4) is not deformed, and - the grippers (401, 402) are movable relative to one another between a plurality of stepped positions in different planes and / or at different heights, allowing the insertion of straight sections (4b, 4a) of the coils (4) one at a time into the stator slots (106) at different angular positions of the star (100) of the stator (S1) to be assembled; 27. The apparatus (500) of claim 26.

28. 28. The apparatus (500, 600) of claim 26 or claim 27, wherein the grippers (401, 402) include push-out elements (407) operable to push out the straight portions (4a, 4b) of the coil (4) from the grippers (401, 402) for insertion into the stator slots (106).

29. a support structure (502) to which the spindle (501) is constrained, and for the spindle (501) and / or the support structure (502), a first position in which the carriage (505) does not block the spindle (501) and the star (100) supported by the spindle (501) is not trapped within the carriage (505); a first position, in which the carriage (505) extends around the spindle (501) and surrounds the star (100) supported on the spindle (501); An apparatus (500) according to any one of the preceding claims.

30. 30. The device (500) according to claim 29, wherein the carriage (505) has an inner cylindrical surface (508) that is complementary to the star (100) supported on the spindle (501) and that opens outward with longitudinal openings (509) into which the manipulators (400) of the coils (4) are inserted to accommodate the straight portions (4a, 4b) of the coils (4) in the respective stator slots (106) of the star (100).

31. 31. The device (500) of claim 30, comprising a closure device (510) configured to temporarily and on command close the longitudinal opening (509).

32. The closing device (510) is mounted on the carriage (505) and is a slide or drawer type device; a retracted position in which said panel (511) does not block said longitudinal opening (509) and allows said manipulator (400) to be inserted through said longitudinal opening (509) and into said stator slot (106) of said star (100) supported on said spindle (501); a forward position, in which the panel (511) blocks the longitudinal section opening (509) and prevents the straight sections (4a, 4b) of the coils (4) from escaping from the stator slots (106), 32. The apparatus (500) of claim 31.

33. 29. The apparatus (600) according to any one of the preceding claims 21 to 28, comprising a system (610) for manipulating the sectors (110) of the yoke (101''), the system comprising at least one gripper (620) having movable jaws (621, 622) for gripping / releasing the sectors (110) of the yoke (101''), the gripper being movable to a position for releasing the sectors (110) that close one or more stator slots (106) with straight portions (4a, 4b) of the coils (4) where the sectors (110) are fixed to the star (100).

34. 34. The apparatus (600) of claim 33, comprising one or more fastening elements (611) transportable by a handling system (610) together with each sector (110) of the yoke (101'') and configured to keep the sector (110) of the yoke (101'') constrained to the spindle (601) during assembly of the stator (S2), the fastening elements (611) being removable after assembly is complete.

35. 35. The device (600) according to claim 34, wherein the fastening element (611) is fork-shaped and engages with the two longitudinal ends of the sector (110) of the yoke (101'') and can be inserted into corresponding seats (605) present on the spindle (601), allowing it to span the straight sections (4a, 4b) of the coil (4) inserted in the stator slots (106) of the star (100).

36. 36. The device (600) of claim 35, wherein the fork-shaped element (611) engages with a sector (110) of each yoke (101'') and has at least one tooth (611'') insertable into a seat (605) of the spindle (601), the spindle (601) including at least one lever (612), the tooth (611'') snap-engaging with the corresponding lever (612), the lever being movable to release the tooth (611'') and enable release of each fork-shaped element (611).

37. 37. Device (600) according to claim 36, wherein seats (605) for inserting the fork-shaped elements (611) are arranged circumferentially on the spindle (601) according to a pitch proportional to or corresponding to the pitch between the sectors (110) of the yoke (101''), the spindle comprising at least one lever (612) pivoting on a pin (613) against each seat (605), opposed by a spring (613') and with teeth (612') intended to engage with the teeth (611'') of each fork-shaped element (611).

38. 38. The device (600) of claim 37, wherein the spindle (601) is cylindrical, the levers (612) are arranged radially on the spindle (601), and the pins (613') are arranged tangentially, i.e., perpendicular to each of the levers (612).

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