EP4721251A1 - Apparatus and method for assembling an electric motor - Google Patents

Abstract

An apparatus (10) for assembling an electric motor (100), provided with a stator (101) and two rotors (102, 103), each located on one side of the stator (101) and connected to a driving shaft (106) rotatable with respect to said stator (101), comprises a support structure (11) fixed with respect to a base (20), configured to support the stator (101) and the driving shaft (106), and a first and a second movable support device (12, 13), each suitable to support and move a respective rotor (102, 103) along a movement axis (X) towards the support structure (11).

Description

“APPARATUS AND METHOD FOR ASSEMBLING AN ELECTRIC MOTOR”

FIELD OF THE INVENTION

The present invention concerns an apparatus and method for assembling an electric axial flux electric motors is increasingly widespread because, for the same torque developed, they allow to reduce the overall dimensions compared to radial flux electric motors.

To increase the transmitted torque, it is also known to use two rotors arranged on one side and on the other with respect to the stator and keyed onto a same driving shaft.

The assembly of such an electric motor is complex, since it requires bringing each rotor very close to and almost in contact with the stator, and then fixing it on the driving shaft in a certain position.

The two rotors have to generally be put in phase with each other, or possibly reciprocally offset by a predefined angle.

Due to the permanent magnets positioned on the rotors, however, magnetic forces of attraction and repulsion are generated between them that do not allow them to be stably positioned reciprocally with respect to each other.

In particular, the persistent nature of the permanent magnets provided on the rotors causes each rotor to generate a respective permanent magnetic field that in the proximity of magnetic or magnetizable elements, such as a stator or another rotor for example, can cause forces of attraction and/or repulsion that make it difficult to assemble an axial flux electric motor, if not done in a controlled manner.

The known type of assembly apparatuses provide to fix a first rotor on a workbench, then position the stator and finally the second rotor.

This solution can present problems both in the positioning of the stator with respect to the first rotor, due to the attraction forces that grow rapidly as the two components approach each other, and also in the positioning of the second rotor with respect to the stator, since it is necessary for this to be in phase or in any case have a precise phase shift with respect to the first rotor.

There is therefore the need to perfect an apparatus and method for assembling an electric motor that can overcome at least one of the disadvantages of the state of the art. To do this, it is necessary to solve the technical problem of reciprocally positioning the stator and the respective rotors in a precise manner.

In particular, one purpose of the present invention is to provide an apparatus and perfect a method for assembling an electric motor in a precise manner.

Another purpose of the present invention is to provide an assembly apparatus which is simple to use, even by non-specialized personnel, in any case guaranteeing optimal performance.

Another purpose of the present invention is to perfect an assembly apparatus that allows to position the components of the electric motor in precise and well- defined positions with respect to each other.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In accordance with the above purposes and to solve the technical problem disclosed above in a new and original way, also achieving considerable advantages compared to the state of the prior art, there is provided an apparatus for assembling an electric motor. In particular, the electric motor is an axial flux motor and comprises a stator and two rotors, each arranged on one side of the stator.

The apparatus according to the invention comprises a support structure fixed with respect to a base, configured to support the stator and the driving shaft with its central axis in a horizontal position, and a first and a second movable support device, each suitable to support and move a respective rotor towards the support structure along a movement axis aligned to the central axis.

According to one aspect of the invention, each of the first and second movable support devices comprises a respective sliding shaft and a carriage slidably arranged on the sliding shaft and configured to support a respective rotor of the abovementioned two rotors, wherein each of the sliding shafts comprises respective axial alignment means configured to be aligned, during use, to respective reference means provided on the driving shaft and on the rotors, in order to obtain a predefined angular position between the rotors and the driving shaft. The angular position is preferably univocal.

This achieves the advantage that it is possible to put each rotor in phase with respect to the stator and the other rotor by aligning the respective reference means present thereon to the respective axial alignment means provided on the respective sliding axes, thus defining a predefined angular position between each rotor and the driving shaft which is then kept along the entire travel of the rotor approaching the stator.

In accordance with one aspect of the present invention, each of the axial alignment means comprises a longitudinal groove configured to cooperate with a constraint element provided on at least one of either the rotor or the carriage.

In accordance with one aspect of the present invention, each of the sliding shafts comprises a respective proximal end, that is, the end facing the support structure and arranged, during use, closer to the driving shaft, having a reduced diameter with respect to remaining portion of the respective sliding shaft and configured to be fitted, during use, into a cavity of the driving shaft.

In accordance with some embodiments, the proximal end comprises axial coupling members which prevent possible rotations thereof.

In accordance with another aspect, each of the carriages comprises a coupling seat and each of the movable support devices further comprises a support body suitable for sliding on the respective sliding shaft and configured, on one side, to hold the respective rotor and, on the other side, to be fitted into and removably mounted on the coupling seat.

In accordance with another aspect, the apparatus comprises guide elements arranged in a fixed position with respect to the support structure and each comprising a suitable housing seat configured to support a distal end of the sliding shafts, that is, the opposite end arranged, during use, furthest away from the driving shaft, and which faces the support structure from the opposite side.

According to another aspect, the support structure comprises a first and a second flange arranged parallel to and facing each another, configured to be fixed with respect to the base, between which the stator, during use, is positioned and mounted, wherein the first and second flanges comprise respective openings configured and shaped to allow a respective rotor to pass therethrough when moving along the movement axis.

According to some embodiments, the carriages are driven by means of driving members comprising at least one electric motor.

In accordance with another aspect, each carriage is driven by a respective driving member comprising an electric motor and a transmission shaft configured to transmit the motion to the respective carriage by means of a transmission mechanism.

The present invention also concerns a method for assembling an electric motor, in particular of the axial flux type, comprising a stator and two rotors, each arranged on one side of the stator, and a driving shaft connected to the rotors and rotatable with respect to the stator, wherein the method comprises the steps of:

- mounting the stator on a support structure fixed with respect to a base so that a central axis of the driving shaft is arranged in a horizontal position;

- inserting each of the two rotors onto a respective sliding shaft by aligning reference means provided on each of the rotors to axial alignment means provided on each of the sliding shafts;

- slidingly connecting each of the sliding shafts with the inserted rotors to a respective carriage of, respectively, a first and second movable support device, respectively arranged on one side and on the other side of the support structure;

- aligning each of the axial alignment means of the sliding shafts to respective reference means provided on the driving shaft and connecting each of the sliding shafts to the driving shaft in such a way as to obtain a predefined angular position between each of the rotors and the driving shaft;

- moving the carriages along a movement axis aligned to the central axis towards the support structure until bringing the rotors close to the stator.

In particular, the method provides to bring the rotors almost into contact with a respective side of the stator, so that only a minimum air gap remains between the respectively facing surfaces, suitable for allowing a rotation of the rotors with respect to the stator.

By the term “aligned” with reference to the axes we mean that two axes can be parallel or coincident with each other.

In particular, the movement axis on which the rotors move is coincident with the central axis of the driving shaft and/or of the stator, while the overall movement axis of the respective carriage that supports a rotor is parallel to the central axis.

According to some embodiments, the method provides to move the carriages simultaneously in an opposite direction with respect to each other, in particular towards each other.

According to some embodiments, the method provides to move the carriages by means of driving members comprising at least one electric motor.

According to some embodiments, the method also provides a step of mounting the stator pre-assembled with the driving shaft and with a covering element by means of a first and second flanges provided with openings for the passage of the rotors.

In accordance with some embodiments, in which the axial alignment means comprise a longitudinal groove, the step of aligning each of the axial alignment means to the respective reference means comprises coupling a constraint element, provided on at least one of either a rotor or the respective carriage, to the longitudinal groove.

According to other embodiments, the method also provides a step of removing each of the sliding shafts from the driving shaft, by pulling them out from the support structure, and a step of fixing support elements of each rotor to the driving shaft.

DESCRIPTION OF THE DRAWINGS

These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of one embodiment, or of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a schematic lateral view of an apparatus for assembling an axial flux electric motor according to the present invention;

- figs. 2 and 3 are partial schematic views of the apparatus of fig. 1 in different operating steps of the assembly of the axial flux electric motor;

- fig. 4 is a schematic three-dimensional view of a part of the apparatus of fig. 1.

We must clarify that the phraseology and terminology used in the present description, as well as the figures in the attached drawings also in relation as to how described, have the sole function of better illustrating and explaining the present invention, their purpose being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications. DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

With reference to fig. 1, this shows an apparatus 10 according to the present invention for assembling an electric motor 100, in particular an axial flux electric motor.

The electric motor 100 comprises a stator 101 and two rotors 102, 103 respectively arranged on either side of the stator 101.

The stator 101 and the rotors 102, 103 have a discoidal shape and in the assembled state each of the rotors 102, 103 is arranged facing one side of the stator 101.

In particular, each rotor 102, 103 is located almost in contact with respect to the stator 101, there being provided only a minimum air gap separating the respectively facing flat surfaces of the rotors 102, 103 and of the stator 101, which allows the rotors 102, 103 to rotate with respect to the stator 101.

The apparatus 10 according to the invention is in particular suitable for allowing a symmetrical and simultaneous positioning of the two rotors 102, 103 with respect to the stator 101.

The stator 101 is provided with a central hole 105 in which a driving shaft 106 is arranged made through.

The driving shaft 106 comprises respective end portions 114, 115 that are arranged protruding with respect to the stator 101 and are configured to each connect to a respective rotor 102, 103.

Around the central hole 105 of the stator 101 there are distributed a plurality of coils 104 (fig. 4), or windings, in which, during use, an electric current is made to circulate in order to induce an electromagnetic field.

Bearings 107 or similar sliding elements can be arranged between the stator 101 and the driving shaft 106, which are suitable for defining a separation between the two components and allowing a rotation of the driving shaft 106 with respect to the stator 101. The two rotors 102, 103 each comprise a support element 109 and a plurality of permanent magnets 108 fixed by means of suitable resins to the support element 109. The support element 109 can be a ferromagnetic body suitable for closing the magnetic circuit formed by the support element 109 and the permanent magnets 108.

The support element 109 is preferably a flange.

The rotors 102, 103 have respective through holes 110, 111 by means of which they can be fitted into the driving shaft 106 and keyed onto it in such a way as to drag it in rotation due to the effect of the interaction between the inductive electromagnetic field generated by the electric current circulating in the coils 104 of the stator 101 and the magnetic field induced in the permanent magnets 108 of the rotors 102, 103.

The stator 101 is generally associated with a cover element 112, or casing, which covers its peripheral surface and which, in the assembled condition of the electric motor 100, also covers the respective peripheral surfaces of the two rotors 102, 103.

The apparatus 10 according to the invention comprises a fixed support structure 11, suitable for supporting the stator 101 and the driving shaft 106 in such a way that a central axis C of the driving shaft 106 is arranged in a horizontal position.

The support structure 11 can be fixed to a base 20, for example a work surface or bench, or suchlike, by means of known fixing means, in particular of the removable type, for example screws, bolts or suchlike (not shown).

According to some embodiments, the support structure 11 comprises a first flange 36 and a second flange 37 which are arranged parallel and facing each other, which are uniquely fixed with respect to the base 20 and between which, during use, the stator 101 is positioned and fixed, preferably already pre-assembled with the driving shaft 106 by means of the bearings 107 and with the cover element 112.

The flanges 36, 37 cooperate to support the stator 101 and the driving shaft 106 with the central axis C arranged in a horizontal position.

The flanges 36, 37 comprise respective openings 38 suitable for allowing the passage of a respective rotor 102, 103 therethrough.

In particular, the flanges 36, 37 are arranged in a vertical direction, with the respective openings 38 arranged coaxial to each other and, during use, coaxial to the central axis C of the driving shaft 106, allowing the transit of a respective rotor 102, 103 in a horizontal direction.

The apparatus 10 also comprises a first 12 and a second support device 13 movable along a movement axis X parallel to the central axis C, wherein each support device 12, 13 is suitable for supporting and moving a respective rotor 102, 103 along the movement axis X.

In particular, the support devices 12, 13 are suitable for moving a respective rotor 102, 103 towards the stator 101 and the driving shaft 106 along a movement axis X aligned to, preferably coincident with, the central axis C.

The first 12 and the second movable support device 13 are arranged on one side and on the other of the support structure 11 and substantially symmetrical with respect thereto.

According to some embodiments, each support device 12, 13 comprises a carriage 14, 15, or slide, associated with a respective driving member 16, 17 configured to translate it along the movement axis X.

The driving member 16, 17 can preferably be a linear actuator configured to move a respective carriage 14, 15, either directly or by means of motion transmission kinematic mechanisms. The driving members 16, 17 are configured to move the carriages 14, 15 in an opposite sense with respect to each other.

According to some embodiments, the driving members 16, 17 comprise at least one electric motor 21, 22.

According to possible embodiments, not shown, the driving members 16, 17 can be connected to a common electric motor 21, 22 by means of motion transmission mechanisms.

According to possible embodiments, each driving member 16, 17 can comprise an electric motor 21, 22 and a transmission shaft 23, 24 configured to transmit motion, by means of a suitable transmission mechanism 30, to a respective carriage 14, 15.

For example, the transmission mechanism 30 can comprise a screw-nut screw device.

According to possible variants, the transmission shaft 23, 24 could transmit motion to the carriage 14, 15 by means of a transmission mechanism 30 of the pinion-rack type. These transmission mechanisms 30 allow to move the carriages 14, 15 with precision in opposite senses in the direction of the movement axis X, in such a way as to approach the rotors 102, 103 supported thereon simultaneously, and substantially symmetrically, to the stator 101.

According to preferred embodiments, the transmission mechanism 30 comprises a ball screw, having the task of transforming sliding friction into rolling friction, which allows a more precise and efficient positioning than the traditional screw-nut screw mechanism.

Although two electric motors 21, 22 are shown in fig. 1, each configured to move one of the carriages 14, 15, according to possible variants, a single electric motor 21 can also be provided suitable for cooperating by means of appropriate kinematics with both of the transmission shafts 23, 24 and the carriages 14, 15.

The apparatus 10 can also comprise guide means 18, 19 configured to cooperate with a respective carriage 14, 15 in order to keep it aligned along the movement axis X during its translation. As shown by way of example in fig. 4, the guide means 18, 19 can comprise one or preferably a pair of tracks 47 suitable to be fitted into and cooperate with respective seats 48 provided on the carriages 14, 15.

According to one aspect of the present invention, the apparatus 10 comprises a pair of sliding shafts 25, 26, each configured to be positioned, during use, made through in a respective hole 110, 111 of a respective rotor 102, 103 and in a through hole 39 of a respective carriage 14, 15 allowing the sliding thereof.

Each sliding shaft 25, 26 is provided with respective axial alignment means 27, 28 configured to allow to align each sliding shaft 25, 26 in a precise and predefined position with respect to the respective rotor 102, 103 slidably arranged thereon and with respect to the stator 101.

According to some embodiments, the axial alignment means 27, 28 comprise a longitudinal line or groove 29 extending substantially at least for the entire travel completed by the respective rotor 102, 103 along the respective sliding shaft 25, 26.

According to some variants, the axial alignment means 27, 28 comprise two or more longitudinal grooves 29 arranged parallel to each other.

According to some variants, the axial alignment means 27, 28 comprise a plurality of notches positioned in succession to each other along a horizontal axis parallel to the movement axis X.

According to possible embodiments, the axial alignment means 27, 28 can have a contrasting color with respect to the respective sliding shaft 25, 26 on which they are arranged. In this way, they can be easily identified visually by an operator, making it easier to orient them with respect to the movement axis X.

During use, each of the axial alignment means 27, 28 can be advantageously aligned, respectively, on one side to the first reference means 31 provided on the driving shaft 106, and on the other side to second reference means 32 provided on each rotor 102, 103 (fig. 4).

According to preferred embodiments, the first reference means 31 are located on the end portions 114, 115 of the driving shaft 106 protruding with respect to the stator 101.

Once the axial alignment means 27, 28 are reciprocally aligned to the respective reference means 31, 32, the rotor 102, 103 is put “in phase” with the stator 101, that is, there is defined a predefined angular position of the rotor 102, 103 which is maintained for the entire travel along the respective sliding shaft 25, 26.

According to some embodiments, a constraint element 32A is provided on the rotor 102, 103, or on the carriage 14, 15 supporting the rotor 102, 103, which is suitable to be fitted into and slide in the longitudinal groove 29. In this case, the constraint element 32 A itself can act as second reference means 32. The constraint element 32 A can for example be embodied as a protruding tooth.

In this case, it can be provided that the first reference means 31 on the driving shaft 106 are also provided with a groove, not shown, in which the constraint element 32A can slide.

The constraint element 32A can be integral with the rotor 102, 103 or with the respective carriage 14, 15.

According to possible variants, not shown, there can be provided two longitudinal grooves, or slots, arranged parallel to each other on one or on each sliding shaft 25, 26 and on one or on each end portion 114, 115 of the driving shaft 106, and two protruding constraint elements 32A suitable for sliding in the grooves. According to such variants, the constraint elements 32A can both be provided on one of either the rotor 102, 103 or the respective carriage 14, 15, or each can be provided on a different component. According to some embodiments, instead of the longitudinal groove there can be provided a slot with a shaped section, for example “T” or dovetail shaped, in which a constraint element with a mating shape is suitable to slide.

This provides a further guarantee that, once the rotor 102, 103 is fitted into a sliding shaft 25, 26 and the latter is fixed with respect to the stator 101, the respective rotor 102, 103 is axially clamped so that it cannot rotate, and therefore remains in the predefined angular position for the entire travel along the sliding shaft 25, 26 in the direction of movement axis X up to the stator 101.

Therefore, a correct reciprocal positioning both between a respective rotor 102, 103 and the stator 101, and also between the two rotors 102, 103 is achieved.

According to some embodiments, the sliding shafts 25, 26 comprise a proximal end 33 (fig. 3) facing the support structure 11 and arranged, during use, closer to the driving shaft 106, and an opposite distal end 34 (fig. 4) facing away from the support structure 11 and arranged, during use, further away from the driving shaft 106.

The proximal end 33 of each of the sliding shafts 25, 26 comprises a portion with a reduced diameter, configured to fit into a respective internal cavity 35 of the driving shaft 106 so as to couple thereto when the stator 101 is fixed on the support structure 11.

As shown by way of example in figs. 2 and 3, two distinct and separate cavities 35 can be provided, each arranged on one side and on the other of the driving shaft 106.

According to some embodiments, the proximal end 33 and the cavity 35 are provided with mating axial coupling members 49, configured to axially couple the two components preventing a relative rotation therebetween. The axial coupling members 49 can comprise surfaces having a striated profile, also called “splined”.

Such a striated profile can extend over the entire circumference of the proximal end 33, only over part of it, or in a partial manner.

According to possible variants, not shown, the axial coupling members can comprise elements with a mating shape of a different type, for example with a polygonal shape, dovetail shape, or other, suitable to allow a connection in the axial direction, preventing a reciprocal rotation.

Preferably, the thickness of the cavity 35 and the diameters of the sliding shaft 25, 26 and of the proximal end 33 are such that when a sliding shaft 25, 26 is coupled to the driving shaft 106 and fitted into the cavity 35, the external surfaces of the driving shaft 106 and of the sliding shaft 25, 26 are located in continuity with each other.

In this way, as the carriage 14, 15 advances, the respective rotor 102, 103 can pass directly from the sliding shaft 25, 26 to the driving shaft 106, in particular on a respective end portion 114, 115, in a continuous manner, maintaining the predefined angular position with respect thereto.

According to some embodiments, the apparatus 10 can also comprise guide elements 41, 42 having the function of guiding and supporting the distal end 34 of the respective sliding shafts 25, 26 so as to keep them correctly aligned in a horizontal direction.

These guide elements 41 , 42 are each arranged on the side of one of the carriages 14, 15, opposite with respect to the support structure 11 and in a fixed position with respect thereto. The guide elements 41 , 42 are integral with respect to the base 20, for example fixed to it by means of removable fixing means.

The guide elements 41, 42 are provided with a housing seat 43 configured to house and support the distal end 34 of a respective sliding shaft 25, 26 substantially without play.

According to some embodiments, not shown, it can be provided that also the distal end 34 has a different diameter, smaller or larger depending on alternative embodiments, with respect to the portion of the sliding shaft 25, 26 cooperating with the rotor 102, 103, whereby the housing seat 43 can also act as a stop and end- of-travel element for the sliding shaft 25, 26.

Thanks to the use of the carriages 14, 15 and the sliding shafts 25, 26 provided with the axial alignment means 27, 28, it is therefore possible to guarantee a univocal and predefined positioning of the rotors 102, 103 with respect to the stator 101, regardless of the attractive and repulsive forces in play.

According to some embodiments, the carriages 14, 15 can each comprise a coupling seat 40 to which a rotor 102, 103 can be coupled, in particular already pre-assembled with support element 109 and permanent magnets 108.

According to some embodiments, each movable support device 12, 13 can comprise a respective support body 44, 45 associated with the respective carriage 14, 15, configured on one side to hold one of the rotors 102, 103 and on the other side to be fitted into the coupling seat 40 and be removably mounted thereon, for example by means of fixing means comprising screws, bolts or suchlike.

Each of the two support bodies 44, 45 is advantageously slidably arranged on the respective sliding shaft 25, 26 and is provided with a through hole 46.

This solution makes the connection between the rotor 102, 103 and the respective carriage 14, 15 in the assembly step, and also the subsequent disconnection once the rotor 102, 103 has been fixed to the driving shaft 106 easier.

According to possible variants, it can also be provided that the rotor 102, 103 is directly connected to the coupling seat 40 with respective known fixing means of the screw type or suchlike.

The operation of the apparatus 10 for assembling an axial flux electric motor 100 described heretofore, which corresponds to the method according to the present invention, comprises the following steps.

The method comprises a step in which the stator 101, preferably already preassembled with the driving shaft 106 and with the cover element 112, is installed on the support structure 11, and in particular clamped between the first 36 and the second flange 37 by means of removable fixing means.

The method provides to insert each rotor 102, 103 onto a sliding shaft 25, 26, preferably on the side of the proximal end 33, making it slide towards the distal end 34 until it abuts against the coupling seat 40 of a carriage 14, 15.

According to preferred embodiments, the method provides to attach the rotor 102, 103 onto a support body 44, 45 and make the latter slide, together with the rotor 102, 103, towards the coupling seat 40 and subsequently fix it thereto with fixing means.

According to one aspect of the invention, the method provides to slidingly connect each of the sliding shafts 25, 26, each with a rotor 102, 103 mounted, to a respective carriage 14, 15 of one of the movable support devices 12, 13 respectively arranged on one side and on the other side of the support structure 11.

According to one aspect of the invention, the method provides to align the reference means 32 provided on the rotor 102, 103 to the axial alignment means 27, 28. In this step, the method can provide to couple the constraint element 32A to the longitudinal groove 29. The method according to the invention provides to align the axial alignment means 27, 28 of the sliding shafts 25, 26 to the first reference means 31 and connect the sliding shaft 25, 26 to the driving shaft 106 in such a way as to obtain the predefined angular position between the rotor 102, 103 arranged on the sliding shaft 25, 26 and the driving shaft 106.

The sliding shaft 25, 26 and the driving shaft 106 can be reciprocally connected by means of axial coupling members.

Subsequently, having completed the coupling of both rotors 102, 103 to the respective carriages 14, 15 with a predefined angular position with respect to the sliding shafts 25, 26, the method provides to move the two carriages 14, 15 along the movement axis X towards the support structure 11.

According to some embodiments, the method provides to move the two carriages 14, 15 by means of the driving members 16, 17.

The method provides that the carriages 14, 15 are moved in such a way as to push the respective rotors 102, 103 along the sliding axes 25, 26 and along the driving shaft 106 which is located in continuity therewith, until they are arranged coaxial to the driving shaft 106 and almost in contact with the stator 101.

In the method according to the invention, the driving members 16, 17 can be commanded by means of a control unit 50, for example a PLC (Programmable Logic Controller), which can be configured to command the drive of the electric motors 21, 22 in such a way that they make the carriages 14, 15 complete a predefined travel, or on the basis of signals received from position sensors associated with the carriages 14, 15 and/or with the support structure 11.

Because in the step of aligning the reference means 32 provided on the rotor 102, 103 to the axial alignment means 27, 28 the sliding shafts 25, 26 are further connected with the driving shaft 106, the rotors 102, 103 can only slide axially along the sliding shafts 25, 26 but cannot rotate relative thereto, and the sliding shafts 25, 26 cannot rotate relative to driving shaft 106, a precise positioning of the rotors 102, 103 with respect to stator 101 is achieved, regardless of the attractive and repulsive forces due to the electromagnetic field generated by the magnets 108 of the rotors 102, 103.

In the method according to the invention, the carriages 14, 15 and the respective rotors 102, 103 associated therewith are preferably approached simultaneously and with uniform speeds in the direction of movement axis X towards the support structure 11 and the stator 101.

Preferably, the carriages 14, 15 are moved until a protruding edge 113 of the rotor 102, 103 abuts against the bearings 107 associated with the stator 101.

Subsequently, the method provides a step of removing the sliding shafts 25, 26 from the driving shaft 106, extracting them from the support structure 11, and a step of fixing the support elements 109 of the rotor 102, 103 to the driving shaft 106, for example by means of locking ring nuts or suchlike.

The method also comprises a step in which the flanges 36, 37 of the support structure 11 are removed, so as to allow the extraction of the assembled electric motor 100 to which, possibly, other lateral cover elements, not shown, can be applied.

It is clear that modifications and/or additions of parts may be made to the apparatus 10 and to the method for assembling an electric motor 100 as described heretofore, without departing from the field and scope of the present invention, as defined by the claims.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art will be able to achieve other equivalent forms of apparatus and method for assembling an electric motor, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the claims.

Claims

1. Apparatus (10) for assembling an electric motor (100) comprising a stator (101) and two rotors (102, 103), each of said rotors (102, 103) being arranged on a respective side of said stator (101), and a driving shaft (106) connected to said rotors (102, 103) and rotatable with respect to said stator (101), said apparatus (10) comprising a support structure (11) fixed with respect to a base (20) and configured to support said stator (101) and said driving shaft (106) with its central axis (C) in a horizontal position, and a first and a second movable support device (12, 13), each movable support device (12, 13) being configured to support and move a respective rotor (102, 103) towards said support structure (11) along a movement axis (X) aligned to said central axis (C), characterized in that each of said movable support devices (12, 13) comprises a carriage (14, 15) slidably arranged on a respective sliding shaft (25, 26) and configured to support a respective rotor of said two rotors (102, 103), wherein each sliding shaft (25, 26) comprises respective axial alignment means (27, 28) configured to be aligned to respective reference means (31, 32) provided on said driving shaft (106) and on said rotors (102, 103) to obtain a predefined angular position between said rotors (102, 103) and said driving shaft (106).

2. Apparatus (10) as in claim 1, characterized in that each of said axial alignment means (27, 28) comprises a longitudinal groove (29) configured to cooperate with a constraint element (32A) provided on at least one of either said rotor (102, 103) or said carriage (14, 15).

3. Apparatus (10) as in claim 1 or 2, characterized in that each said sliding shaft (25, 26) comprises a proximal end (33) having a reduced diameter with respect to a remaining portion of said sliding shaft (25, 26) and configured to be fitted into a cavity (35) of the driving shaft (106).

4. Apparatus (10) as in any one of the preceding claims, characterized in that each carriage (14, 15) comprises a coupling seat (40) and each of said movable support devices (12, 13) further comprises a support body (44, 45) suitable for sliding on the respective sliding shaft (25, 26) and configured, on one side, to hold the respective rotor (102, 103) and, on the other side, to be fitted into and removably mounted on said coupling seat (40).

5. Apparatus (10) as in any one of the preceding claims, characterized by comprising guide elements (41, 42) arranged in a fixed position with respect to said support structure (11), each of said guide elements (41, 42) comprising a housing seat (43) configured to support a distal end (34) of said sliding shafts (25, 26) and facing said support structure (11) from the opposite side.

6. Apparatus (10) as in any one of the preceding claims, characterized in that said support structure (11) comprises a first (36) and a second (37) flanges arranged parallel to and facing each other, configured to be fixed with respect to the base (20) with said stator (101) positioned and mounted therebetween, wherein said first and second flanges (36, 37) comprise respective openings (38) configured and shaped to allow a respective rotor (102, 103) to pass therethrough when moving along said movement axis (X).

7. Apparatus (10) as in any one of the preceding claims, characterized in that each carriage (14, 15) is driven by a respective driving member (16, 17) comprising an electric motor (21, 22) and a transmission shaft (23, 24) configured to transmit the motion to the respective carriage (14, 15) by means of a transmission mechanism (30).

8. Method for assembling an electric motor (100) comprising a stator (101) and two rotors (102, 103), each of said rotors (102, 103) being arranged on a respective side of said stator (101), and a driving shaft (106) connected to said rotors (102, 103) and rotatable with respect to said stator (101), said method being characterized by comprising the steps of:

- mounting the stator (101) on a support structure (11) fixed with respect to a base (20) so that a central axis (C) of said driving shaft (106) is arranged in a horizontal position;

- inserting each of the two rotors (102, 103) onto a respective sliding shaft (25, 26) by aligning reference means (32) provided on each of said rotors (102, 103) to respective axial alignment means (27, 28) provided on said sliding shaft (25, 26);

- slidingly connecting each of said sliding shafts (25, 26) with the inserted rotors (102, 103) to a respective carriage (14, 15) of, respectively, a first and second movable support device (12, 13) respectively arranged on one side and on the other side of said support structure (11);

- aligning each of said axial alignment means (27, 28) of the sliding shafts (25, 26) to respective reference means (31) provided on said driving shaft (106) of the electric motor (100), and connecting each of said sliding shafts (25, 26) to said driving shaft (106) in such a way as to obtain a predefined angular position between each of said rotors (102, 103) and said driving shaft (106);

- moving said carriages (14, 15) along a movement axis (X) aligned to said central axis (C) towards said support structure (11) until bringing said rotors (102, 103) close to said stator (101).

9. Method as in claim 8, characterized by providing to move said carriages (14, 15) towards each other simultaneously.

10. Method as in claim 9 or 10, characterized by providing to move said carriages (14, 15) by means of driving members (16, 17) comprising at least one electric motor (21, 22).

11. Method as in any one of claims 8 to 10, characterized in that said axial alignment means (27, 28) comprise a longitudinal groove (29) and the step of inserting each of the two rotors (102, 103) onto a respective sliding shaft (25, 26) by aligning said reference means (32) allows the coupling of a constraint element (32A), provided on at least one of either said rotor (102, 103) or the respective carriage (14, 15), to said longitudinal groove (29).

12. Method as in any one of claims 8 to 11, characterized by comprising a step of removing each of said sliding shafts (25, 26) from said driving shaft (106), by pulling them out from said support structure (11), and a step of fixing support elements (109) of each rotor (102, 103) to said driving shaft (106).

13. Method as in any one of claims 8 to 12, characterized by comprising a preassembling step, prior to the step of mounting said stator (101) on the support structure (11), wherein said pre-assembling step comprises assembling said stator (101) with said driving shaft (106) and with a cover element (112), and said step of mounting said stator (101) comprises positioning a first (36) and a second (37) flanges on opposite sides of the stator (101) arranged therebetween, said first (36) and second (37) flanges being provided with respective openings (38) dimensioned to allow said rotors (102, 103) to pass therethrough when moved towards said stator (101) along said movement axis (X).