FR3143904A1 - Rotor of rotating electric machine and corresponding rotating electric machine - Google Patents

Abstract

Rotor of rotating electric machine and corresponding rotating electric machine The invention relates to a rotor for a rotating electrical machine comprising a rotor shaft extending along an axis of rotation (X) of the rotor, a rotor body (3) comprising a plurality of sheets each having at least one housing (13) extending radially relative to the axis of rotation (X), the sheets being stacked coaxially around the rotor shaft, at least one permanent magnet (11) received in the housing (13) formed in the sheets, the sheets further comprising at least one holding member (15) of the magnet (11) in the housing (13). The invention also relates to a rotating electric machine comprising such a rotor. Figure for abstract: Fig. 2 

Description

Rotor of rotating electric machine and corresponding rotating electric machine

The present invention relates to rotating electrical machines. More specifically, the invention relates to rotating machines implementing permanent magnets integrated into the rotor or stator of the machine. The invention relates more particularly to a rotor for such rotating electrical machines.

Technical background

A rotating electrical machine may be in the form of an alternator, an electric motor, or a reversible machine that can operate in both modes. As is known per se, rotating electrical machines comprise a stator and a rotor secured to a shaft. The rotor may be secured to a driving and/or driven shaft.

The stator is generally mounted in a housing configured to rotate the shaft on bearings by means of rolling bearings. The stator may comprise a stator body consisting of a stack of thin sheets forming a crown, the inner face of which is generally provided with notches open towards the inside to receive a winding. The winding comprises, for example, polyphase windings whose outputs are connected to a rectifier bridge.

Furthermore, the rotor may comprise a rotor body formed by at least one pack of sheets, for example in a magnetic material, in particular steel, as well as poles formed by a plurality of permanent magnets received in housings defined in the rotor body. The magnets may be of different materials, in particular ferrites, rare earths.

Given the manufacturing tolerances of the various parts, it is possible that the magnets are poorly plated inside the housings. This is likely to cause deterioration of the magnets due to impacts between the magnets and the internal faces of the housings during operation of the machine, or due to impacts between two magnets during operation of the machine. There is also a risk linked to loss of balance, which can cause an increase in noise, vibrations, and can damage the machine.

Magnets can be of different sizes, which can make it more difficult to insert them and hold them in position in the housings formed in the sheets.

A disc can be placed at each axial end of the rotor body and can each close one end of the housings. These discs can also ensure balancing of the rotor. Balancing can be carried out by adding or removing material.

According to a known solution, a mixture of resin or varnish and a hardener is injected into the rotor body via vents provided for this purpose, in particular at the level of the balancing disks, and flows between the magnets to keep them in position after a polymerization time. The varnish can coat the magnet in its entirety or partially in order to hold it mechanically.

However, a certain fragility of the sheet metal pack at high speeds was observed due to centrifugal force.

Also, such a solution with resin or varnish injection requires adding specific vent shapes to the design tools as well as cutting specific shapes in the sheet metal pack, allowing the injection of the varnish and/or the machining of the balancing disks. This generates additional costs for the cutting tools and can cause magnetic losses on the rotor circuit, as well as mechanical fragility of the balancing disks.

In addition, this solution requires the use of two chemical entities: varnish and hardener, and therefore induces environmental pollution. This solution also requires the use of, among other things, a hydraulic system, a polymerization oven, which generates costs associated with implementation and maintenance, pollution of the machines with fluids, and requires specific technical knowledge. Finally, this solution limits the repeatability of the position of the magnets.

The invention aims to find a solution for holding the magnets in their housings, both when the rotor is stationary and rotating. The invention also aims to find a solution that can be applied in a standard manner to increase the repeatability of the position of the magnets. Another object of the invention is to reduce, or even eliminate, magnetic flux leaks and to optimize the electromagnetic performance of the machine.

For this purpose, the invention relates to a rotor of a rotating electrical machine comprising a rotor shaft extending along an axis of rotation of the rotor, a rotor body comprising a plurality of sheets each having at least one housing extending radially relative to the axis of rotation, the sheets being stacked coaxially around the rotor shaft, and at least one permanent magnet received in the housing formed in the sheets.

According to the invention, the sheets further comprise at least one member for holding the magnet in the housing.

This includes a mechanical holding organ.

Such a solution allows the magnet or magnets to be retained in the housings defined in the sheets, eliminating the need for chemicals such as varnish or resin and hardener, which simplifies the tooling and reduces their costs as well as minimizing the polluting impact. In addition, the rotor and more specifically the magnets can be recycled more easily if they are not polluted by such chemicals. It is also possible to remove any shapes or vents for varnish injection, which improves the magnetic field.

Finally, the repeatability of the position of the magnets is increased and the mechanical strength of the sheet metal pack is improved.

The rotor may further comprise one or more of the following features described below, taken separately or in combination.

The sheets are, for example, annular in shape and have an inner diameter and an outer diameter.

According to one embodiment, the rotor comprises a plurality of permanent magnets received in respective housings formed in the sheets, such that two consecutive magnets have end faces converging towards each other.

The magnets can be arranged in a mirror image along an axial plane passing between the magnets.

For example, the magnets are arranged in a “V” shape or a double series of “V” shapes.

The converging faces are alternately internal faces on the rotor shaft or inner diameter side and external faces on the outer diameter side of the laminations.

The rotor may include at least one holding member for each magnet.

Alternatively, the rotor may comprise at least one common holding member for at least two magnets.

The holding member may be produced by an added part arranged in the housing in mechanical contact with an internal end face of at least one magnet, the internal end face being arranged on the rotor shaft side.

The attached holding member or members allow the magnet or magnets to be retained in the housings defined in the sheets, so as to counteract the magnetic effect which attracts the magnets towards the internal diameter.

The magnets have, for example, a parallelepiped shape. The holding member can be arranged against a small face of at least one magnet.

Different variants of positioning of the holding member relative to the magnet can be envisaged. The holding member can be substantially at the center of the small face, or at a corner of the small face of the magnet.

The retaining member may be selected from a pin, a cylindrical pin, a solid pin, a spring pin, a split pin, a headed pin, a screw, a pin.

The holding member is made of, for example, a metal or plastic material.

The housings are, for example, through-face of a sheet metal. The holding member mounted in a housing can pass through a predefined number of sheets. For example, the holding member can pass through the entire sheet metal stack. It is also possible to fit a holding member through each axial face of the sheet metal stack.

According to one embodiment, the rotor comprises two disks arranged axially on either side of the rotor body. The disks are held by at least one fixing member force-fitted in associated fixing holes provided in the disks and the plurality of sheets. The sheets have walls delimiting the housing, elastically deformed under the effect of the force-fitting, so as to retain the magnet in the housing.

The fixing holes are of smaller dimensions, for example of smaller diameter, than the fixing member so as to allow force fitting.

The fixing holes can be made in the sheets on the rotor shaft side or the inner diameter side.

When there is a plurality of magnets, the fixing holes may be provided between two housings on the rotor shaft side so as to be opposite two converging faces of the magnets.

According to an exemplary embodiment, the fixing holes have a predefined number of recesses.

The recesses are advantageously opposite the areas to be deformed. The recesses can be placed so that the deformation is concentrated towards the magnets, when inserting the fixing member into the fixing hole.

The recesses may be arranged so that the fixing hole has at least three contact areas with the fixing member, and so that at least two contact areas are oriented towards the magnets.

For example, at least three recesses may be provided so that the fixing hole has at least three contact areas with the fixing member.

For example, the fixing holes have three offsets angularly by 120°. In another example, the fixing holes have four offsets.

The fixing holes can be cylindrical, triangular or rectangular in shape for example.

The recesses can be in the form of lobes, or rectangular slots, or even triangular slots, or pointed or toothed.

The invention also relates to a rotating electrical machine comprising a rotor as defined above. The rotating machine further comprises a stator which can be arranged around the rotor.

Other advantages and characteristics of the invention will appear more clearly on reading the following description given as an illustrative and non-limiting example, and the appended drawings among which:

shows an example of the realization of a rotor for an electric rotating machine.

is a perspective view of a rotor body of the .

is a schematic representation of an exemplary embodiment of a pin retaining a magnet in a housing of the rotor body.

is a schematic representation of another exemplary embodiment of a headed pin retaining a magnet in a housing of the rotor body.

is a schematic view of a portion of the rotor body showing a common holding member for two magnets in communicating housings of the rotor body.

is a schematic view of a portion of the rotor body showing housings for receiving the magnets and a mounting hole for receiving a force-fitted mounting member.

shows the portion of the rotor body with the fixing member force-fitted into the fixing hole.

is a schematic view of a portion of the rotor body showing a fixing hole according to another exemplary embodiment.

In these figures, identical elements have the same reference numbers.

The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference is to the same embodiment, or that the features apply only to a single embodiment. Single features of different embodiments may also be combined or interchanged to provide other embodiments.

In the description, certain elements may be indexed, for example first element or second element. In this case, it is a simple indexing to differentiate and name close but not identical elements. This indexing does not imply a priority of one element over another and such names can easily be interchanged without departing from the scope of the present invention. This indexing also does not imply an order in time.

Detailed description

The invention relates to a rotating electrical machine, hereinafter referred to as a machine. This machine may be an electric motor or may be capable of operating in alternator mode, or may be a reversible type electrical machine.

The machine comprises a rotor 1, one embodiment of which is shown in the and a stator (not shown). The rotor 1 may be arranged inside the stator (not shown), which comprises, for example, a concentrated or distributed winding. This stator makes it possible to generate a rotating magnetic field for driving the rotor in rotation, in the case of a synchronous motor, and in the case of an alternator, the rotation of the rotor induces an electromotive force in the windings of the stator.

The invention relates more specifically to the rotor 1. The rotor 1 comprises a rotor shaft 2 with an axis of rotation X. The rotor shaft 2 can be made of a non-magnetic material.

The rotor 1 comprises a rotor body 3 extending axially along the axis of rotation X. The rotor body 3 is mounted on the rotor shaft 2.

This rotor body 3 is preferably made of ferromagnetic material. Two disks 5 can be plated on either side of the rotor body 3. The disks 5 are arranged on the axial end faces, i.e. along the axis of rotation X, of the rotor body 3. These disks 5 can also be used to balance the rotor 1. They are also called balancing disks. The disks 5 can be made of non-magnetic material, for example aluminum.

One or more fixing members 6 such as screws can hold the disks 5 with the rotor body 3 and ensure compactness of the rotor 1. A plurality of fixing holes 7 can be made in the disks 5 and the rotor body 3 to each allow the passage of a fixing member 6. The fixing holes 7 are preferably through holes. The fixing holes 7 are provided in the sheets on the side of the rotor shaft 2.

The rotor body 3 can be formed here by a stack of sheets or at least one pack of sheets stacked along the axis of rotation X. The sheets extend in a radial plane perpendicular to the axis of rotation X. The superimposed sheets are advantageously identical. They can be held together by any suitable means, for example in a non-limiting manner by clipping, by rivets axially passing through the stack of sheets, with staples, buttons, or by welding or gluing or any other technique. The sheets are preferably made of magnetic steel.

For mounting on the rotor shaft 2, the rotor body 3 may have a central opening 9 ( ). This central opening 9 may be of generally cylindrical shape. The fixing may be done by any suitable means, for example by force-fitting the rotor shaft 2 inside the central opening 9, or using a fixing device.

The sheets are annular in shape. The sheets and more generally the rotor body 3 have an internal periphery delimiting the central opening 9 having a first diameter called the internal diameter D1, and an external periphery of a second diameter called the external diameter D2.

Furthermore, the rotor 1 comprises at least one permanent magnet 11. Preferably, the rotor 1 comprises a plurality of permanent magnets 11. Depending on the applications, the magnets 11 can for example be made of rare earth or ferrite.

The magnet or magnets 11 are arranged in corresponding housings 13 of the rotor body 3. The sheets each have at least one housing 13 extending radially relative to the axis of rotation X.

The housings 13 pass through from one face to the other of a sheet. When the sheets are stacked, the housings 13 communicate with each other and define one or more cavities axially passing through a plurality of sheets, or even all of the sheets, and therefore the rotor body 3 from one side to the other, i.e. from one axial end face to the other. According to an alternative embodiment, a housing 13 can be closed by a bottom on an axial end of the rotor body 3 for axially holding the magnet 11. The disks 5 can also ensure axial retention of the magnets 11 inside the housings.

A magnet 11 may be inserted inside a cavity. Alternatively, several magnets 11 may be stacked on top of each other inside a cavity.

The magnets 11 located in two consecutive housings 13, or more generally in two consecutive cavities, are of alternating polarities.

The housing(s) 13 have a main portion 131 of a shape complementary to that of the magnet 11.

The magnets 11 have for example a parallelepiped shape, in particular a rectangular parallelepiped shape. The corners of the magnets 11 can optionally be beveled. In a complementary manner, the main portion 131 of the housings 13 is in this example a parallelepiped shape, in particular a rectangular parallelepiped.

The magnets 11 thus have two opposite upper and lower faces 11a, connected to two lateral faces 11b by two end faces 11c, 11d. When the magnets 11 are housed in the rotor body 3, the upper and lower faces 11a correspond to axial end faces, along the axis of rotation X.

One of the end faces 11d is a so-called internal face located on the side of the axis of rotation X (i.e. on the side of the rotor shaft not visible on the ) or located on the side of the internal periphery or the internal diameter D1 of the sheets, more generally of the rotor body 3. The other end face 11c is a so-called external face located on the side of the external periphery or the external diameter D2 of the sheets, more generally of the rotor body 3.

The arrangement of a plurality of magnets 11 can be done so that two consecutive magnets 11 have end faces 11c, 11d which converge towards each other.

Two consecutive magnets 11 can be arranged in a mirror image along an axial plane passing between the two. In a complementary manner, two consecutive housings 13 are symmetrical along the axial plane passing between them.

In particular, the magnets 11 are, in the illustrated example, arranged to form a “V” pattern or two series of “V”s for example when two series of magnets 11 are arranged radially. The faces converging towards each other are alternately internal faces 11d and external faces 11c. The magnets 11 form for example an angle of the order of 45° with a perpendicular to the axis of rotation X. Thus, two consecutive magnets 11 have the same polarities on their substantially opposite faces.

The rotor body 3, and more precisely the sheets, further comprise at least one member 15, 17 for holding the magnet 11 in the housing 13.

A holding member 15, 17 may be provided for each magnet 11 or alternatively be common for at least two magnets 11. It may be one or more added parts, i.e. which are not formed in one piece with the laminations or the rotor body 3, or alternatively, the holding member may be formed directly by the laminations. Embodiments are detailed below.

First embodiment

According to a first embodiment, the holding member 15 is produced by a part added to the housing 13 and making it possible to stress the magnet 11 in this housing 13. The term “added part” means that the holding member 15 is produced by an additional part not already provided in the rotor body 3 and which can be separated from the rotor body 3.

Furthermore, according to the first embodiment at least one holding member 15 such as a pin is provided for each magnet 11.

The holding member 15 is therefore interposed between the sheet metal and the magnet 11, to ensure that the magnet 11 is held inside the corresponding housing 13. The holding member 15 forms a stop.

The holding member 15 may be made of a metallic or plastic material. Any other material may be considered.

In the example illustrated, the holding member 15 is made by a pin. It may be a cylindrical pin, a solid pin, a spring pin, a split pin, a headed pin. Alternatively, it could be a screw, or even a pin.

In the illustrated example, the holding member 15, such as a pin, is of elongated shape in an axial direction, that is to say that it extends parallel to the axis of rotation X once inserted into the housing 13. The holding member 15, such as a pin, can extend over the entire height of the magnet 11, or over the entire height of the cavity receiving the magnet or magnets 11. The holding member 15 can pass through a predefined number of sheets, or even the entire stack of sheets. Alternatively, at least one holding member 15 can be mounted on each axial face of the stack of sheets.

In this case, the holding member 15, such as a pin, is mounted compressed in a secondary portion 133 of the housing 13. The secondary portion 133 has a shape complementary to that of the holding member 15, such as a pin. In this example, it is cylindrical. Such a cylindrical shape does not or only slightly disturb the passage of the field of the magnetic circuit. According to the embodiment described, the secondary portion 133, for example cylindrical, is arranged on the side of the internal diameter D1.

In particular, the holding member 15, such as a pin, is arranged in the housing in mechanical contact with the inner end face 11d of at least one magnet 11. In the case of a magnet 11 of parallelepiped shape, the holding member 15 is arranged against a small inner face. The holding member 15 such as a pin then exerts a radial force on the magnet 11 so as to press the magnet 11, and more precisely its outer end face 11c, against the corresponding outer face (i.e. on the side of the outer periphery of the sheet metal) of the housing 13. Thus, the magnet or magnets 11 are pressed towards the outer diameter D2. This makes it possible to counteract the magnetic force which attracts the magnet 11 towards the inner diameter D1 and to fix the magnet 11 during rotation so as not to lose the balance.

Different positioning variants can be envisaged. The holding member 15 can be arranged in a centered manner opposite the internal end face 11d of the magnet 11, as shown in FIG. . In this case, the secondary portion 133, for example cylindrical, of the housing 13 is provided on the side of the internal diameter D1, and in a centered manner opposite the internal end face 11d of the magnet 11.

Alternatively, the holding member 15 may be arranged opposite a corner of the magnet 11, as shown schematically in FIGS. 3a, 3b. Thus, the holding member 15 may exert a force on the internal end face 11d and on a lateral face 11b so as to press the external end face 11c and the opposite lateral face 11b against the corresponding faces of the housing 13. In this case, the secondary portion 133, for example cylindrical, of the housing 13 is arranged eccentrically, opposite a corner of the internal end face 11d of the magnet 11.

According to yet another variant, when the holding member 15 is a headed pin, as shown diagrammatically in the , it can also axially hold the magnet 11 in the housing 13. The head of the pin forms an axial holding tab for the magnet 11 which comes to bear against an axial end face 11a of the magnet 11.

Second embodiment

A second embodiment schematized on the , differs from the first embodiment in that at least one holding member 15 is common for at least two consecutive magnets 11. Only the differences from the first embodiment are detailed below.

To do this, two consecutive housings 13 have a common secondary portion 135 to receive the holding member 15. The latter thus ensures that each magnet 11 is held radially and tangentially to the outer diameter.

The shape of the secondary portion 135 is complementary to that of the holding member 15. In the case of a pin for example, the secondary portion 135 may have a generally cylindrical shape.

The shape of the common secondary portion 135 can be designed so as to increase the forces towards the magnets 11. To do this, the secondary portion 135 can optionally have one or more ears 136.

Third embodiment

According to a third embodiment, illustrated in Figures 5a to 5c, the holding member is not produced by a part added in the housing 13 but directly by the sheet metal, more precisely by using the deformation of the sheet metal.

This solution uses the fixing holes 7 already present to deform the sheet metal and more precisely the area of the sheet metal presenting the housing 13, when the fixing member or members 6 are inserted.

To do this, the fixing members 6 are force-fitted into the associated fixing holes 7. The fixing holes 7 are of smaller dimensions, for example of smaller diameter, than the fixing members 6 so as to allow force-fitting. The walls 17 of the sheets which delimit the housings 13 are elastically deformed under the effect of the force-fitting. The magnets 11 are thus constrained into position tangentially in the housings 13.

When there is a plurality of magnets 11, the fixing holes 7 are provided between two housings 13 on the side of the rotor shaft 2. Each fixing hole 7 is located opposite two converging faces, here external 11c, of the magnets 11.

The shape of the fixing holes 7 can be optimized so as to control, direct the deformations of the material in at least one desired direction during force mounting. More precisely, the shape of the fixing holes 7 can be adapted so as to direct the deformation zones towards the magnets 11. The shape of the fixing holes 7 can be designed so as to increase the contact surface between the sheet metal and the fixing member 7 in the direction of the magnets 11 on the opposite side.

The fixing holes 7 may have one or more recesses 71 for this purpose.

The recesses 71 must not be opposite the length of a magnet 11 / a housing 13.

The recesses 71 are advantageously opposite the areas for which deformation is desired. The recesses 71 can be placed so that the deformation is concentrated towards the magnets 11 / towards their housings 13, when inserting the fixing member 6 into the fixing hole 7.

The recesses 71 may be arranged so that the fixing hole 7 has at least three contact zones with the fixing member 6, and so that at least two contact zones are oriented towards the magnets 11/towards their housings 13. The fixing holes 7 may have, for example, at least three recesses 71.

In the particular example of the , the fixing holes 7 have three recesses 71 offset angularly by 120°, which makes it possible to direct the deformations according to the arrows F between two recesses 71. The material is thus deformed in a desired direction, in particular towards the magnets 11.

Such a configuration is not limiting. The recesses 71 may be distributed according to another configuration around the fixing hole 7. In the particular example of the , the fixing holes have four recesses 71. Three of the recesses 71 are closer to the inner periphery and the rotor shaft than to the outer periphery, the fourth being closer to the outer periphery.

The 71 recesses can be in the form of lobes ( ), or rectangular slots ( ), or even triangular, pointed or toothed slots.

The fixing holes 7 may be of generally cylindrical shape. In the previous examples, the recesses 71 may be provided around such a cylindrical shape.

Alternatively, the fixing holes 7 may be triangular in shape for example, so as to concentrate the deformations towards the magnets 11.

According to yet another variant, the fixing holes 7 may have a square, rectangular section, or any other shape suitable for the passage of the fixing members 6 and making it possible to direct the deformations towards the magnets 11 with or without recesses 71.

Thus, the embodiments previously described with an added part or using the deformation of the sheet metal to hold the magnet 11 make it possible to avoid the previous solution requiring the injection of a material such as a resin or varnish into the housings 13, so as to block the magnets 11 in the housings 13.

The magnets 11 are mechanically held for example by holding members 15 such as pins mounted to bear against the internal end faces 11d of one or more corresponding magnets 11. When the magnets 11 are arranged radially, and more particularly in a “V”, and not along the external periphery of the rotor, the holding members 15 make it possible to radially press the magnets 11 into the housings 13 so that the maximum stress is towards the external diameter of the rotor 1. This makes it possible to stabilize the magnets 11 during centrifugation.

The magnets 11 can also be mechanically held directly by the sheets, when the fixing members 6 are force-fitted into the fixing holes 7 already provided for tightening the balancing discs 5 and the pack of sheets. The material is then deformed at the fixing holes 7 which compresses the housings 13 and the walls 17 delimiting these housings 13 make it possible to retain the magnets 11 in the latter.

According to either embodiment, the magnet or magnets 11 can be maintained in a simple manner during the different speed cycles of the rotor 1, making it possible to maintain balance and have an acceptable noise level without damaging the machine.

Claims (10)

Rotor (1) of a rotating electrical machine comprising:

• a rotor shaft (2) extending along an axis of rotation (X) of the rotor,
• a rotor body (3) comprising a plurality of laminations each having at least one housing (13) extending radially relative to the axis of rotation (X), the laminations being stacked coaxially around the rotor shaft (2), and
• at least one permanent magnet (11) received in the housing (13) formed in the sheets,
• characterized in that the sheets further comprise at least one member (15, 17) for holding the magnet (11) in the housing (13).

Rotor (1) according to the preceding claim, comprising a plurality of permanent magnets (11) received in respective housings (13) formed in the sheets, so that two consecutive magnets (11) have end faces (11c, 11d) converging towards each other. Rotor (1) according to claim 2, comprising at least one holding member (15, 17) for each magnet (11). Rotor (1) according to claim 2, comprising at least one holding member (15) common to at least two magnets (11). Rotor (1) according to one of claims 1 to 4, in which the holding member (15) is produced by an added part arranged in the housing (13) in mechanical contact with an internal end face (11d) of at least one magnet (11), the internal end face (11d) being arranged on the side of the rotor shaft (2). Rotor (1) according to the preceding claim, in which the magnets (11) have a parallelepiped shape, and in which the holding member (15) is arranged against a small face (11d) of at least one magnet (11). Rotor (1) according to one of claims 1 to 3, comprising two disks (5) arranged axially on either side of the rotor body (3) and held by at least one fixing member force-fitted in associated fixing holes (7) formed in the disks (5) and the plurality of sheets, and in which the sheets have walls (17) delimiting the housing (13), elastically deformed under the effect of the force-fitting, so as to retain the magnet (11) in the housing (13). Rotor (1) according to the preceding claim, in which the fixing holes (7) have a predefined number of recesses (71). Rotor (1) according to the preceding claim, in which the fixing holes (7) have three recesses (71) angularly offset by 120°. Rotating electrical machine comprising a rotor (1) according to one of the preceding claims.