FR3146248A1 - Axial magnetic flux electric machine equipped with a double cooling device. - Google Patents

Abstract

Axial magnetic flux electric machine with 2 identical stators 10,20 assembled on a spacer 30 mounted inside a casing 70 closed by a cover 80, cooled using 2 separate devices: the first is a cooling circuit of the stators 10,20 by a liquid in contact with the coils 13 and the yokes 14 in the chambers 15a,25a; The second is a cooling circuit of the rotor disk 41a by air pulsed by a turbine 60 carried by the rotor 40, circulating in the chamber constituted by the casing 70 and the cover 80. Figure for the abstract: Fig. 6

Description

Axial magnetic flux electric machine equipped with a double cooling device. TECHNICAL FIELD OF THE INVENTION

The present invention relates to an electric motor or generator known as axial magnetic flux motor comprising at least one discoid rotor with several permanent magnet pads and at least one flat annular stator with several coils distributed radially in a regular manner and whose axis is oriented parallel to that of the rotor.

STATE OF THE ART

There are two main concepts: one comprising a central stator and two lateral rotors, illustrated by publication GB2482928, and conversely one comprising a central rotor arranged between two stators, illustrated by publication FR3064422. Specifically, the invention relates to the second type.

In this concept, the rotor is confined between the stators, it cannot be cooled. If there is excessive heating generated mainly by eddy currents, the magnets can lose their magnetic characteristics when the temperature exceeds a critical value. In addition, radiation heating of the stators can further increase the rotor temperature. The solution proposed in the publication FR3110767 to mitigate the heating is the very strong segmentation of the magnet blocks. The eddy currents are then drastically reduced.

Regarding stators, in publication GB2482928, the solution proposed to mitigate energy losses is to replace the stacking of laminations with a “Soft Magnetic Composites – SMC”. The stator pad is made from a soft iron powder, the particles of which are coated with an electrical insulator. The powder is compressed in a mold to obtain the desired shape, then undergoes heat treatment to ensure cohesion and mechanical resistance.

In publication FR3046888, the cooling means deployed is an exchange by conduction between the coolant, circulating in a chamber in each casing, and the stator pad, and this through the support sheet of the pads and the casing fabric.

Now, the cooling capacity determines the maximum power of the machine. To improve cooling, it is necessary to ensure that the heat sources, the Joule effect in the windings, the eddy currents causing iron losses in the stator and rotor, are in direct contact with the flow of a cooling fluid, whether liquid or gaseous.

PRESENTATION OF THE INVENTION

• circulation d’un fluide liquide pour les stators, au contacts des bobinages et de la culasse ;
• circulation d’air sur les surfaces du disque rotor.

The object of this invention is to propose a double cooling device:

• circulation of a liquid fluid for the stators, in contact with the windings and the yoke;
• air circulation over the rotor disc surfaces.

According to a first characteristic, the 2 identical stators, assembled in a mirror image on a spacer, have a composite material frame comprising a radial annular plate, which carries stator pads and two more or less cylindrical axial extensions internally and externally surrounding the windings and the yoke, and these being connected by an annular cover, the assembly constitutes a circulation chamber for a cooling liquid in direct contact with the windings.

• via un conduit unique, situé dans la zone la plus haute de la machine, porté par l’entretoise séparant les deux stators, et qui communique avec un conduit radial réalisé dans cette entretoise;
• puis, dans chaque carcasse de stator, circule dans un conduit axial interne au prolongement extérieur;
• enfin, par un évidement à l’extrémité du conduit axial parvient à la chambre de refroidissement.

According to a second feature, the coolant reaches the cooling chambers

• via a single conduit, located in the highest area of the machine, carried by the spacer separating the two stators, and which communicates with a radial conduit made in this spacer;
• then, in each stator frame, circulates in an internal axial conduit to the external extension;
• finally, through a recess at the end of the axial duct reaches the cooling chamber.

• sort de la chambre de refroidissement par un évidement en communication avec un second conduit axial interne au prolongement axial extérieur de la carcasse ;
• puis, se déverse dans une chambre radiale dans l’entretoise ;
• enfin, par un conduit similaire à celui de l’alimentation, et porté par l’entretoise, est évacué hors de la machine.

According to another characteristic, the coolant, having reached the lower part of the machine:

• exits the cooling chamber through a recess communicating with a second axial conduit internal to the external axial extension of the carcass;
• then, flows into a radial chamber in the spacer;
• finally, by a conduit similar to that of the supply, and carried by the spacer, it is evacuated from the machine.

• est agencée à l’intérieur d’un carter fermé par un couvercle afin de créer une chambre isolée de circulation de l’air;
• possède en périphérie extérieure plusieurs oreilles de fixation;
• permet la circulation de l’air entre les stators et le carter.

According to a first characteristic relating to the cooling of the rotor, the spacer carrying the two stators:

• is arranged inside a housing closed by a cover in order to create an isolated air circulation chamber;
• has several fixing ears on the outer periphery;
• allows air circulation between the stators and the housing.

According to a second feature, the rotating outer ring of the rotor guide bearing is arranged to carry a turbine, forcing air circulation.

• expulsion de l’air entre le palier central du carter, portant l’axe support du roulement du rotor, et l’ouverture centrale du stator gauche;
• cheminement radial de l’air réchauffé entre les faces du carter et du couvercle du stator gauche qui jouent le rôle d’échangeur;
• contournement du stator gauche, passage par les ouvertures laissées par l’entretoise, contournement du stator droit;
• par la poussée exercée par la turbine, cheminement radial de l’air vers le centre entre les couvercles de la machine et du stator droit (second rôle d’échangeur);
• poursuite du cheminement entre le moyeu du rotor et l’ouverture centrale du stator droit;
• pénétration, par le centre, dans l’entrefer séparant le disque rotor et le stator droit;
• contournement du rotor;
• pénétration, dans l’entrefer séparant le rotor et le stator gauche;
• évacuation par le centre, par aspiration par la turbine.

According to another characteristic, the circuit traveled by the air is this, or its reverse depending on the design of the turbine and the direction of rotation:

• expulsion of air between the central bearing of the casing, carrying the rotor bearing support shaft, and the central opening of the left stator;
• radial path of the heated air between the faces of the casing and the left stator cover which act as an exchanger;
• bypass the left stator, pass through the openings left by the spacer, bypass the right stator;
• by the thrust exerted by the turbine, radial path of the air towards the center between the covers of the machine and the right stator (second role of exchanger);
• continuation of the path between the rotor hub and the central opening of the right stator;
• penetration, through the center, into the air gap separating the rotor disk and the right stator;
• rotor bypass;
• penetration, in the air gap separating the rotor and the left stator;
• evacuation through the center, by suction through the turbine.

DETAILED DESCRIPTION OF THE INVENTION

These characteristics, aims and advantages of the present invention will appear on reading the detailed description which follows and with regard to the appended drawings given as non-limiting examples and in which:

• stator sur entretoise;
• entretoise sur carter;
• disque rotor sur son moyeu;
• roulement sur son axe;
• turbine sur le roulement.

is a first sectional view of the complete machine, showing different fixing devices:

• stator on spacer;
• spacer on crankcase;
• rotor disc on its hub;
• rolling on its axis;
• turbine on the bearing.

• de la paroi des carcasses des stators;
• de la toile de carter.

is a second cross-section of the complete machine, showing the busbar crossing:

• from the wall of the stator frames;
• of the crankcase canvas.

is a third sectional view of the complete machine, showing the stator coolant supply and discharge ducts.

is a sectional view of the left stator and spacer assembly mounting in the crankcase.

is a cross-sectional view of the rotor installation.

is a sectional view of the final assembly phase: assembly of the right stator of the feed-through plate, the busbars and cover.

is a cross-sectional view of the stator coolant circulation.

is a cross-sectional view of the air flow in the air gaps.

The electric machine 1 presented in a first section on the is composed of an engine block arranged in a casing 70 and a closing plate 80.

• du stator gauche 10 lié à l’entretoise 30 à l’aide des vis 16 traversant le prolongement extérieur 11e de la carcasse 11;
• du stator droit 20, miroir du gauche, lié de la même manière à l’entretoise 30 par les vis 16 traversant le prolongement extérieur 21e de la carcasse 21;
• de la plaque entretoise centrale 30, comportant plusieurs excroissances périphérique 30a, pour être fixée par les vis 31 au carter 70;
• du rotor discoïde 40 soutenu par un roulement unique à double rangée de billes 50, porté par l’axe 52, emmanché dans le carter 70.

The engine block is essentially made up of:

• of the left stator 10 connected to the spacer 30 using the screws 16 passing through the external extension 11e of the frame 11;
• of the right stator 20, mirror of the left, linked in the same way to the spacer 30 by the screws 16 passing through the external extension 21e of the frame 21;
• of the central spacer plate 30, comprising several peripheral protrusions 30a, to be fixed by the screws 31 to the casing 70;
• of the discoid rotor 40 supported by a single double-row ball bearing 50, carried by the axle 52, fitted into the casing 70.

• d’une partie radiale 11r,21r qui supporte les plots statoriques 12;
• une extension axiale extérieure 11e,21e plus ou moins annulaire, comprenant une première zone planeF _b d’appui sur l’entretoise 30, une seconde zone plane à extrémité opposée, d’accueil du couvercle 15,25 et des zones épaissies pour le passage des vis 16 de fixation commune de la carcasse et du couvercle sur l’entretoise;
• une extension axiale intérieure 11i,21i plus ou moins annulaire, plane à son extrémité pour l’accueil du couvercle 15, fixé à l’aide des boulons 18,19.

the stators 10,20 comprise a frame 11,21 made of non-magnetic material, preferably composite and consisting of:

• of a radial part 11r,21r which supports the stator pads 12;
• an external axial extension 11e, 21e more or less annular, comprising a first flat zone F _b for support on the spacer 30, a second flat zone at the opposite end, for receiving the cover 15, 25 and thickened zones for the passage of the screws 16 for common fixing of the frame and the cover on the spacer;
• an internal axial extension 11i,21i more or less annular, flat at its end for receiving the cover 15, fixed using the bolts 18,19.

The outer axial extensions 11e, 21e and the inner axial extensions 11i, 21i form, with the cover 15, 25, a cooling liquid circulation chamber.

the openings in the radial parts 11r, 21r are closed by the stator pads 12, fixed by a bead of glue and sealing 12a.

These pads 12 are preferably made of soft magnetic composite powder “Soft Magnetic Composites”. This material offers satisfactory performance and, above all, low energy losses by eddy current. The shape, obtained by molding, and the assembly of the pads make it possible to easily create the isthmus between two consecutive pads.

The (functional) face of the stator pads 12 facing the rotor disk 41 is unique for all the pads and is designated by F _c . By a mounting tool, or a machining means, the faces F _c and F _b are made common and contribute to a high precision of the air gaps.

• les bobines 13 sont posées;
• les carcasses 14, en tôles enroulées, sont rapportées, de préférence par collage;
• les couvercles 15,25 peuvent alors être posés.

After this precise assembly of the stator pads 12 with the frames 11,21:

• coils 13 are placed;
• the carcasses 14, made of rolled sheets, are attached, preferably by gluing;
• the 15.25 covers can then be fitted.

• du disque 41, comprenant 3 parties distinctes :
  • une structure porteuse 41,a en forme de «soleil» car composée d’une partie centrale cylindrique, d’où partent plusieurs branches radiales. Cette structure peut être en matériau amagnétique ou composite de résine chargée en fibres;
  • de plusieurs secteurs d’aimants 41,b chacun pouvant être monobloc ou segmenté. Ils sont collés à la structure «soleil» 41a;
  • d’un «cerclage» 41,c appelé aussi frette pour contrer la centrifugation des aimants;
• du moyeu 42;
• du roulement 50, muni d’une collerette 50a.

The complementary element to the stators to form the electric machine is the rotor 40. It is made up of:

• from disc 41, comprising 3 distinct parts:
  • a supporting structure 41,a in the shape of a “sun” because it is composed of a cylindrical central part, from which several radial branches extend. This structure can be made of amagnetic material or a composite of resin loaded with fibers;
  • of several sectors of magnets 41,b each of which can be monobloc or segmented. They are glued to the “sun” structure 41a;
  • of a “ring” 41,c also called a hoop to counteract the centrifugation of the magnets;
• of hub 42;
• of bearing 50, fitted with a collar 50a.

The hub 42 and the disc 41 are centered on the outer ring of the bearing 50 and these three elements are secured by the screws 51.

• porté par l’axe 52, emmanché dans le carter 70;
• positionné axialement par la rondelle 53 d’équilibrage des entrefers, dont la détermination de l’épaisseur est simple, mais pas exposée ici;
• bloqué axialement par la rondelle 54 et la vis 55;
• monté, grâce au préréglage du contact des bagues intérieures, sans jeu dans les corps roulants et en légère précharge.

Bearing 50 is:

• carried by the axis 52, fitted into the casing 70;
• positioned axially by the washer 53 for balancing the air gaps, the determination of the thickness of which is simple, but not explained here;
• axially blocked by washer 54 and screw 55;
• mounted, thanks to the pre-adjustment of the contact of the inner rings, without play in the rolling bodies and with slight preload.

The air gap balancing washer 53 rests on the casing 70 on the face F _d . By a machining operation of the casing, this face and the face F _a of the spacer 30 are positioned in the same plane. Thus the faces F _a , F _b , F _c and F _d are, after assembly, in the same plane, which facilitates the determination of the thickness of the washer 53 and the precision of the air gaps.

During this machining operation of the casing 70, the receiving bore of the axis 52 supporting the bearing 50 is produced and gives its axis G a good perpendicularity to F _d , which provides a constancy of the thickness of the air gaps 40a.

The hub 42 transmits the rotational movement and the torque to a reducer or a transmission. It can in return, via the splines, if they are cut directly into its mass, undergo external influences, i.e. axial movement and force likely to disturb the balance of the air gaps 40a, detrimental to the operation of the machine and the reliability of the rotor disk 41. Indeed, the stators and the rotor are not directly integral and do not form a block that would be insensitive to external influences.

To obtain axial decoupling, a very low coefficient of friction is required. This is achieved by inserting a ball slide 43 between the hub body 42 and the splines.

This ball slide 43 is made up of several rows of balls, for example 8, regularly distributed radially. The balls are positioned axially by the sleeve 44.

The outer tracks 42a of the balls are cut into the hub 42. The inner tracks 45a are cut externally to the sleeve 45 provided internally with the grooves 45b.

The ball retaining sleeve 44 is stopped axially on the left by the flange 46 and on the right by the washer 47 and the stop ring 48.

The hub also carries the resolver target 93, axially blocked by the washer 94, mounted tightly.

The resolver itself 91 is carried by the cover 80 to which it is fixed by the screws 92.

A ground 56, mounted in the hub and in contact with the washer 54, protects against possible Parisite currents which could damage the bearing 50, the balls 43 and the tracks 42a, 45a of the slide.

an air turbine 60 is fitted onto a projection 50b of the bearing 50.

The cover 80 is fixed to the casing 70 using the screws 81. The entire machine is fixed to a transmission (reducer or gearbox) using the screws 82.

The section of the electric machine presented on the shows the output of the electrical conductors 12a associated with the three phases and 12b associated with the neutral.

The coils 12 being confined in the chambers 15a, 25a for circulation of the cooling fluid, the conductors must first make a crossing of the carcass 11, 21. In this carcass an opening is made to receive a plate 11a, 21a crossed by the four conductors. The passage of the conductors is sealed relative to the plate, for example by resin, and the plate is sealed relative to the carcass, for example by a seal.

the conductors must then make a crossing of the casing canvas 70. An opening 70a is made to receive a plate 71 crossed by the two groups of four conductors. This plate is permanently held after the installation of the cover 80. Sealing, here, is not necessary.

The section of the electric machine presented on the , according to a third section that we will call vertical, shows the pipes for supplying and discharging the cooling fluid. The supply pipe 31, carried by the central spacer plate 30, is arranged in the upper part of the machine. It is bent and passes through an elastomer block 73 arranged in a notch 70b of the casing 70. The pipe 32, also carried by the spacer plate 30, is arranged in the lower part of the machine. It collects the cooling fluid after it passes through the stators. In the same way, it passes through an elastomer block 73 arranged in a notch 70b of the casing 70.

There is a sectional view of the first stage of assembly of the machine, i.e. installation in the casing 70 of the left stator 10 previously assembled with the spacer 30

There is a sectional view of a second assembly step, i.e. the installation of the pre-assembled rotor 40. After determining its thickness, the air gap balancing washer 53 is engaged on the axis 52, then the rotor 40, the washer 54 and finally the screw 55.

There is a sectional view of a final assembly step, i.e. first the installation of the pre-assembled right stator 20, then the conductor feed-through plate 71 and, to complete the assembly, the installation of the closing plate 80.

There shows in section the cooling circuit of the stators 10, 20. The supply ducts 31 and 32 for discharging the cooling fluid are attached to the spacer plate 30. The pipes communicate with the radial ducts 33, sealed by the covers 36. The sealing at the outlet of the ducts in the spacer 30 towards the frames 11 and 21 is ensured by the O-rings 37. The radial ducts 33 open onto axial ducts 34 of the frames which supply the chambers 15a and 25a of the stators via the communications 35 made at the end of the axial extensions 11e, 21e. The emptying of the chambers 15a and 25a is carried out in a similar manner to the supply via the communication openings 35, then the axial conduits 34, the radial conduits 33 and finally the pipe 32.

There shows the air cooling device of the rotor disk. The turbine sets the air in motion in one direction or the other depending on the design of the blades and the direction of rotation around the machine and the disk. According to one of the representations, the turbine 60 draws air in advance of the disk by the edge 60a, and ejects it by the edge 60b. The air circulates in the turbine in the direction 61a.

• d’abord, dans le passage 61b entre le carter et le couvercle du stator de gauche (zone de refroidissement par contact);
• puis contourne la machine selon le parcours 61c;
• retourne vers le centre de la machine selon le parcours 61d en longeant le couvercle du stator droit (zone de refroidissement par contact);
• ensuite pénètre entre le moyeu du rotor et le stator droit selon le parcours 61e;
• pénètre dans l’entrefer entre le disque et le stator droit et réalise le parcours 61f;
• contourne le disque selon le parcours 61g;
• retourne vers la turbine selon le parcours 61h.

L’air circule en circuit fermé, se réchauffe dans les entrefers et se refroidit en contournant les stators.The air takes circuit 61:

• first, in passage 61b between the crankcase and the left stator cover (contact cooling area);
• then go around the machine according to route 61c;
• returns to the center of the machine along path 61d along the right stator cover (contact cooling zone);
• then enters between the rotor hub and the right stator along path 61e;
• enters the air gap between the disk and the right stator and completes the path 61f;
• bypass the disc according to the 61g path;
• returns to the turbine along route 61h.

The air circulates in a closed circuit, heats up in the air gaps and cools down as it bypasses the stators.

Claims (7)

Axial magnetic flux electric machine
characterized in that the stators 10,20 are identical and assembled in a mirror image on a spacer 30. Axial magnetic flux electric machine, according to claim 1, characterized in that the stators 10, 20 have a composite material frame 11, 21 comprising a radial annular plate 11r, 21r which supports stator pads 12 and two more or less cylindrical axial extensions internally 11i, 21i and externally 11e, 21e surrounding the windings 13 and the yoke 14, and these extensions being connected by an annular cover 15, 25, the assembly constitutes a chamber 15a, 25a for circulation of a cooling liquid in direct contact with the windings. Axial magnetic flux electric machine, according to claims 1 or 2, characterized in that the cooling liquid reaches the cooling chambers, via:

• a single conduit 31, located in the highest zone of the machine, carried by the spacer 30 separating the two stators 10, 20, and which communicates with a radial conduit 33 made in this spacer;
• then, an internal axial conduit 34 in the external extension 11e,21e in each frame 11a,21a of the stators;
• finally, a recess 35, at the end of the axial conduit 34, for communication with the cooling chamber 15a, 25a.

Electric machine with axial magnetic flux, according to any one of the claims, characterized in that the cooling liquid, having reached the lower part of the machine:

• exits the cooling chamber through a recess 35 in communication with a second axial conduit 34 internal to the external axial extension 11e, 21e of the casing;
• then, flows into a radial chamber 33 in the spacer 30;
• finally, by a conduit 32 similar to that of the supply, and carried by the spacer 30, it is evacuated from the machine.

Electric machine with axial magnetic flux, according to claim 1 characterized in that the spacer 30 carrying the two stators 10,20:

• is arranged inside a housing 70 closed by a cover 80 in order to create an isolated air circulation chamber;
• has several fixing ears 30a on the outer periphery;
• allows air to circulate between the stators 10,20 and the casing 70;

Axial magnetic flux electric machine, according to claims 1 or 5, characterized in that the rotating outer ring of the rotor guide bearing 50 has an arrangement 50b for carrying a turbine 60 forcing the circulation of air. Axial magnetic flux electric machine, according to claim 6, characterized in that the circuit traveled by the air is this, or its reverse depending on the design of the turbine and the direction of rotation of the rotor:

• expulsion of air through the edge 60b of the turbine between the central bearing of the casing 70, carrying the support axis of the bearing 50 of the rotor 40, and the central opening of the left stator 10;
• radial path of the heated air between the faces of the casing 70 and the cover 15 of the left stator along the path 61b, playing the role of an exchanger;
• bypassing the left stator 10, passing through the openings left by the spacer 30, bypassing the right stator 20 along the path 61c;
• by the thrust exerted by the turbine 60, radial path of the air towards the center between the covers 80 of the machine 25 and the right stator 20 (second role of exchanger) according to the path 61d;
• continuation of the path between the rotor hub and the central opening of the right stator according to path 61e;
• penetration, through the center, into the air gap 40a separating the disk 41 of the rotor, from the right stator 20 along the path 61f;
• bypassing the disk 41 of the rotor 40, according to the path 61g;
• penetration, in the air gap 40a separating the disk 41 of the rotor of the left stator 10 along the path 61h;
• evacuation through the center, by suction through the turbine 60, according to the path 61a.