ROTOR OF A VARIABLE-RELUCTANCE SYNCHRONOUS MOTOR

Abstract

A process for assembling a rotor of a variable-reluctance synchronous motor, characterised in that it comprises the steps of: i. preparing a plurality of discs having a through-cavity for each polar sector for housing at least a magnet; ii. positioning the discs in sequence along an axis of rotation for forming the rotor, so that the through-cavities are aligned to one another; iii. preparing magnets having an identical depth that is smaller than the depth of the rotor, and a frontal section that is identical to or smaller than the area of the cavity; iv. calculating the number of magnets to be inserted, for each polar sector, in a sequence so as to occupy only part of the total depth of the rotor as a function of the performances to be obtained; v. inserting the calculated number of magnets in a series of cavities aligned for each polar sector.

The invention also relates to a rotor of a variable-reluctance synchronous motor assembled using the process set out above.

Claims

1. A process for assembling a rotor of a variable-reluctance synchronous motor, comprising: i. preparing a plurality of discs, wherein each disc has at least a through-cavity for each polar sector for housing at least a magnet; ii. positioning the plurality of discs in sequence along an axis of rotation for forming the rotor, so that said through-cavities are aligned to one another in a parallel direction to said axis of rotation; iii. preparing a plurality of said magnets with a predefined depth that is identical for at least a part of said magnets and having a section area, according to a plane that is perpendicular to the direction of said axis of rotation, that is equal to or smaller than the access area of said through-cavity, said predefined depth of each magnet being smaller than the total depth of the rotor; iv. calculating the number of magnets to be inserted, for each polar sector, in a sequence along said direction parallel to said axis of rotation, so as to occupy only part of the total depth of the rotor as a function of predetermined performances of motor torque which are to be obtained; v. inserting the calculated number of magnets in at least a through-cavity of each polar sector so as to occupy the aligned through-cavities of a plurality of said discs arranged in sequence up to obtaining the depth defined by the calculated number of magnets.

2. The process for assembling a rotor of a variable-reluctance synchronous motor according to claim 1, wherein said step of inserting includes each polar sector having a plurality of through-cavities suitable for housing said magnets and the insertion of said magnets takes place in at least one of the through-cavities.

3. The process for assembling a rotor of a variable-reluctance synchronous motor according to claim 1, wherein the step of inserting includes said magnets being arranged symmetrically with respect to said axis of rotation in each disc.

4. The process for assembling a rotor of a variable-reluctance synchronous motor according to claim 1, wherein the step of preparing the plurality of said magnets includes preparing magnets having a predefined depth that is identical for all the magnets or having a depth that is a multiple or sub-multiple of said predefined depth.

5. The process for assembling a rotor of a variable-reluctance synchronous motor according to claim 1, wherein the step of preparing said discs includes preparing a predefined module and the module comprises a predetermined number of said discs; said process comprising a step of realising “magnetized” modules comprising magnets inserted in the cavities of each polar sector and a step of realising “empty” modules without magnets, wherein said “magnetized” modules and said “empty” modules are mutually interchangeable as a function of the torque performances of the motor that are to be obtained.

6. The process for assembling a rotor of a variable-reluctance synchronous motor according to claim 5, wherein said step of calculating being carried out by calculating the number of “magnetized” modules to be used for realising the rotor according to the torque performances that are to be obtained; said process including placing in sequence the calculated number of “magnetized” modules with the “empty” modules, so as to form the rotor.

7. The process for assembling a rotor of a variable-reluctance synchronous motor according to claim 1, wherein said step of inserting includes each of said magnets having a section area that is complementarily-shaped with respect to the access area of said plurality of through-cavities and includes the insertion of said magnets occurring in at least one of the through-cavities for each polar sector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Further characteristics and advantages of the present invention will become more apparent from the indicative and thus non-limiting description of a preferred, but not exclusive, embodiment of a rotor of a variable-reluctance synchronous motor, as illustrated in the accompanying drawings, in which:

[0042] FIG. 1 is a schematic front view of a first configuration of the rotor lamination according to the prior art;

[0043] FIG. 2 is a schematic front view of a second configuration of the rotor lamination according to the prior art;

[0044] FIG. 3 is a perspective view of a rotor lacking magnets according to the present invention;

[0045] FIG. 4 is a perspective view of a rotor during the step of inserting magnets according to the present invention;

[0046] FIG. 5 is a perspective view of a rotor in which only a first module of the motor comprises magnets according to the present invention;

[0047] FIG. 6 is a perspective view of a rotor in which more than one module of the motor comprises magnets according to the present invention;

[0048] FIG. 7 is a perspective view of a module of the rotor according to the present invention in which the laminations forming the rotor are highlighted;

[0049] FIG. 8 illustrates, in a schematic lateral view, a section of the rotor of FIG. 5 according to the process set out in the description, according to a vertical plane located along the axis of rotation of the rotor.

[0050] In the following description, the identical reference numerals indicate parts that are identical or corresponding in the various views.

DETAILED DESCRIPTION

[0051] The present invention relates to the technical field of the assembly of a rotor for a variable-reluctance synchronous motor, and specifically to the optimisation of the step of arranging the magnets internally of the rotor and the rotor thus-assembled.

[0052] With reference to the figures mentioned, the number 1 generally denotes a rotor for a variable-reluctance synchronous motor according to the present invention.

[0053] The process for assembling the rotor 1 of a variable-reluctance synchronous motor is characterised in that it comprises the steps of:

[0054] i. preparing a plurality of discs 2, usually known as laminations, wherein each disc 2 has at least a through-cavity 2b for each polar sector 2a for housing at least a magnet 4;

[0055] ii. positioning a plurality of discs 2 in sequence along an axis of rotation 3 for forming the rotor 1, so that said through-cavities 2b are aligned to one another in a parallel direction to said axis of rotation 3;

[0056] iii. preparing a plurality of magnets 4 with a predefined depth that is identical for all the magnets and smaller than the total depth of the rotor 1 and having a section area, according to a plane that is perpendicular to the direction of said axis of rotation 3, that is equal to or smaller than the access area of said through-cavity 2b;

[0057] iv. calculating the number of magnets 4 to be inserted, for each polar sector 2a, in a sequence along said direction parallel to said axis of rotation 3, so as to occupy only a part of the total depth of the rotor 1 as a function of predetermined motor torque performances which are to be obtained;

[0058] v. inserting the calculated number of magnets 4 in at least a through-cavity 2b of each polar sector 2a so as to occupy the aligned through-cavities 2b of a plurality of discs 2 arranged in sequence up to obtaining the depth defined by the calculated number of magnets.

[0059] With reference to the last step of the process, the insertion of the magnets 4 into the through-cavities 2b of the discs 2 is illustrated from image 3 to image 6.

[0060] As illustrated in FIG. 7, the discs 2 can have a plurality of through-cavities 2b for each polar sector 2a, so that the insertion step through the aligned through-cavities 2b of the discs 2 arranged in sequence along the rotation axis 3 of the rotor 1 of the magnets 4 includes the magnets preferably being arranged in at least one of the plurality of through-cavities 2b for each polar sector 2a and, further, symmetrically with respect to the rotation axis 3 of the rotor 1.

[0061] In the appended figures, for each polar sector 2a two through-cavities 2b are present, substantially arch-shaped, each of which, like in the prior art, has bridges arranged parallel so as to stiffen the structure and delimit the zone in which to insert the magnets 4. Different to what is illustrated in the appended figures, each of said cavities 2b might have frontal dimensions having a height and width that are different according to the design data. To facilitate the insertion operation, the perimeter of the area of the frontal section of the magnets 4, i.e. the perimeter of the area of the section defined according to a perpendicular plane to the direction of said axis of rotation 3 is complementarily-shaped with respect to the perimeter of the access area of the plurality of through-cavities 2b.

[0062] Alternatively, in order to simplify the insertion step and consequently vary the performance of the motor, one of the two dimensions of the perimeter of the frontal section of the magnets 4 to be used, can be smaller at the respective dimension of the perimeter of the access area of the through-cavity 2b.

[0063] In other alternatives, the dimensions of the magnets 4 of a same motor might be different in frontal height and width according to design needs. Further, FIG. 7 shows how the step of arranging the discs 2 in sequence determines modules 5, i.e. subgroups of discs 2 which can be replaced to vary the performance of the motor torque on the basis of values that are to be reached. A module 5 can be differentiated between an “empty” configuration, in which magnets 4 are not present, and a “magnetised” configuration, in which there is at least one magnet 4 for at least one through-cavity 2b of each polar sector 2a. While in the first case a module 5 is made up of at least one disc 2, in this last case the depth is determined by the depth of the magnets 4 used. In fact, during the step of preparation, the magnets are dimensioned in such a way that the depth thereof is a multiple of the thickness of a single disc 2, so that it can cross a predefined plurality of through-cavities 2b and, consequently, an equal plurality of discs 2, thus creating together with the discs a surface free of steps.

[0064] A module 5 in the “empty” configuration preferably comprises a same number of disc s 2 as a module 5 in the “magnetised” configuration, so that the two configurations of modules 5 are easily interchangeable, as they have to respect a predefined depth of the rotor 1, and so as to obtain a rotor structure that is better balanced.

[0065] In practice, the modules 5 are of two types, on the basis of the presence or the absence of the magnets 4, and a variable number of both is arranged in sequence for the formation of the rotor 1. In FIG. 5 and FIG. 6 the rotor 1 comprises four modules 5: in the first case a “magnetised” module 5 is followed by three “empty” modules 5, while in the second case two “magnetised” modules 5 and two “empty” modules 5 are present.

[0066] The invention further relates to a rotor 1 of a variable-reluctance synchronous motor assembled using the process se t out above.

[0067] The rotor 1 extends along an axis of rotation 3 where a plurality of discs 2 is arranged in sequence, which are angularly sub-divided into a plurality of polar sectors 2a, each of which has at least one through-cavity 2b for housing at least a magnet 4.

[0068] In the preferred embodiment, the magnets 4 used have a predefined depth that is identical for all and smaller than the total depth of the rotor 1, dimensioned in such a way that the value thereof is a multiple of the depth of a single disc 2. Alternatively (not illustrated in the appended figures) the depth of some magnets 4 of the same rotor 1 might be smaller or greater than the predefined depth. In this case, the depth of some magnets 4 might preferably be a multiple or sub-multiple of said predefined depth. In particular, the magnets inserted in the start and end discs of the rotor have a depth that is smaller (preferably a sub-multiple) with respect to the magnets inserted in the most internal zone so as to optimise the performance of the motor.

[0069] Further, the magnets 4 have a frontal section area, i.e. the area of the section defined according to a perpendicular plane to the direction of the axis of rotation 3 of the rotor 1, smaller than the access area to the through-cavity 2b, so that a magnet 4 is inserted to a first depth that is smaller than the total depth of the rotor 1 through the sequence of discs 2 forming the rotor 1 for each polar sector 2a or a plurality of magnets 4 is inserted in sequence along a parallel direction to said axis of rotation 3 to a second depth that is also smaller than the total depth of the rotor 1, as a function of the performances of the motor which are to be obtained, as illustrated in FIG. 8.

[0070] A disc 2, because of how it is structured, has two radial axes of reference: a radial axis of maximum reluctance and a radial axis of minimum reluctance, respectively defined as axis “q” and axis “d”. The through-cavities 2b are arranged along axis “q”, while the polar sectors 2a are defined between two consecutive axes “d”.

[0071] For each polar sector 2a, a plurality of cavities 2b is preferably present in which it is possible to insert a magnet 4, which, during the insertion step, will be arranged symmetrically with respect to the axis of rotation 3 of the rotor 1 and at least one of them in at least a cavity 2b of each polar sector 2a.

[0072] The dimensions of the magnets 4 used contribute to reaching the demanded motor torque performance, and consequently the front section is identical for all the magnets 4 used and, preferably, it is complementarily-shaped with respect to the passage area of the cavities 2b present on each disc 2.

[0073] Alternatively, one of the two dimensions of the frontal section of the magnets 4 can be smaller than the corresponding dimension of the through-cavity 2b of the disc 2.

[0074] For the sake of greater simplicity during the preparation steps, the magnets 4 preferably assume a parallelepiped shape having predefined dimensions on the basis of the motor torque performance to be obtained.

[0075] Further, as described in the foregoing, the depth of the magnets 4 is predefined and equal for all and, given the dimensioning, the insertion of a magnet 4 through the sequence of through-cavities 2b determines the forming of a module 5 in “magnetised” configuration.

[0076] A module 5, i.e. a subgroup of the plurality of discs 2 located in sequence to form a rotor 1 has two possible configurations: a “magnetised” configuration, in which at least one cavity 2b of each polar sector 2a of each disc 2 is crossed by at least a magnet 4 and an “empty” configuration, in which there are no magnets 4 present internally of the module 5.

[0077] A module 5 in this last configuration can also contain a single disc 2, but preferably will contain an equal number to a module 5 in the “magnetised” configuration so as to make the replacement operations between the modules 5 simpler for a change in the performance of the motor torque, as the depth of the rotor 1 is a non-variable predetermined dimension.

[0078] In an alternative embodiment, the modules 5 can have different depths so as to accommodate, in one or more cavities 2b, one or more magnets 4 inserted in sequence. For example, there could be a first module 5 in which in one or more cavities 2b two magnets 4 are present in sequence (“wide” module 5) and a second module 5 in which, in one or more cavities, 2b, only one magnet is inserted (“narrow” module 5). By placing a plurality of “narrow” modules 5 and “wide” modules 5 in sequence, a rotor 1 of the desired dimensions is obtained. In a variant of the alternative embodiment it is possible to realise two or more depth measurements of the magnets 4 and insert one or more in the cavities 2b of the modules according to needs.

[0079] In other words, the magnets 4 and the module can have depths that are different to one another.

[0080] Any modifications or variants which, in the light of the description, are obvious to the person skilled in the sector, must be considered to fall within the scope of protection established by the present invention, according to considerations of technical equivalence.