Electromagnetic motor or generator with two rotors, four stators and an integrated cooling system

Abstract

A permanent-magnet synchronous motor or generator with at least one rotor (2) and at least one stator (3, 8). The motor includes two rotors (2), four stators (3, 8) and a cooling system (7, 7a). The cooling system includes three cooling circuits (7, 7a), i.e. two outer circuits (7) which are each accommodated in a longitudinal outer wall of a casing (8), adjacent to an outermost stator (3, 8), for cooling said outermost stator (3, 8), and an intermediate circuit (7a) located between the two innermost stators (3, 8) in the motor for simultaneously cooling said two stators (3, 8), the central shaft (5) being common to the two rotors (2) which are connected to the central shaft (5) by mechanical means.

Claims

1. A permanent-magnet synchronous electromagnetic motor with axial flux comprising two rotors (2) and four stators (3, 8) with a housing (8), the rotors (2) comprising magnet structures (11) forming magnetic poles, the magnet structures (11) extending all around each rotor (2) mounted so that it can rotate around a median shaft (5), and the four stators (3, 8) comprising windings (4), the motor comprising a cooling system (7, 7a) comprising three circuits (7, 7a) of a cooling fluid, with two external circuits (7) housed respectively in a longitudinal external wall of the housing (8), and being adjacent to an end stator (3, 8) to perform a cooling of the associated end stator (3, 8) and an intermediate circuit (7a) located between the two innermost stators (3, 8) on the motor simultaneously performing a cooling of the two innermost stators (3, 8), the median shaft (5) being common to the two rotors (2), the two rotors (2) being connected to the median shaft (5) by mechanical means (5a, 5b, 6) characterized in that each magnet structure (11) is composed of a plurality of unitary magnets (11a), cover discs (10) of the magnet structures (11) being located axially on each of two opposite axial faces of each rotor (2), the cover discs (10) being made of composite material, the magnet structures (11) being coated in a composite external coating layer defining the exterior contour of each of the rotors (2), the cover discs (10) being coated in the external composite coating layer or placed on a respective axial face of the external coating layer.

2. The motor of claim 1, in which the intermediate circuit (7a) is housed in an intermediate wall (8a, 8b) of the housing (8) extending radially with respect to the common median shaft (5).

3. The motor of claim 2, in which the intermediate wall (8a, 8b) comprises two portions (8a, 8b) extending radially with respect to the common median shaft (5), each portion (8a, 8b) being fastened respectively to one of the innermost two stators (3, 8) on the motor by removable fastening means (16).

4. The motor of claim 1, in which the magnet structures (11) on one of the two rotors (2) are radiantly offset by a predetermined angle with reference to the magnet structures (11) on the other rotor (2), the mechanical means (5a, 5b, 6)) being capable of precisely adjusting the offset of the magnet structures (11) of one rotor (2) with respect to the other rotor (2) during the installation of the rotors on the median shaft (5).

5. The motor of claim 1, in which a binding band (9) surrounds the external coating layer on its external periphery farthest from the median shaft (5).

6. The motor of claim 1, in which the unitary magnets (11a) are constituted by elementary magnet blocks with a mesh structure, the unitary magnets (11a) being bonded by a resin separating them or each inserted into a respective housing defined by one of the meshes of the mesh structure.

7. The motor of claim 6, in which the mesh structure is in the form of a honeycomb.

8. The motor of claim 1, in which each stator (3, 8) comprises concentric windings (4) and a series of teeth (3) with windings (4) wound around each tooth, the teeth (3) being fastened to one another.

9. The motor of claim 8, in which each winding (4) rests on the tooth (3) surrounding at least partly a winding support (14), each winding support (14) comprising or being associated with snap fitting means (15′) cooperating with complementary snap fitting means (3′) on a tooth (3) associated with the winding support (14) so that the winding support (14) is fastened with the associated tooth (3).

10. The motor of claim 9, in which the winding support (14) comprises an intermediate portion (21) on which the winding (4) is wound and a flat cover portion (20) which is farther from the associated tooth (3) in the fastening position of the winding support (14) on the tooth (3), being separated from the tooth (3) by the winding (4) and the intermediate portion (21), the flat cover portion (20) having an external contour axially covering at a distance at least one external turn facing the winding (4) and abutting against the external contour of the winding, whereby the winding support (14) can be a single piece or not.

11. The motor of claim 8, in which the windings (4) of the stators (3, 8) are concentric and are connected to the exterior of the motor in a terminal strip, either in series or in parallel.

12. The motor of claim 1, in which the median shaft (5) has a series of grooves (5a, 5b) longitudinal to the median shaft (5) locally on each portion of the median shaft (5) designed to receive respectively one of the two rotors (2), each rotor (2) having a central cavity (22) having an inside diameter that equals the outside diameter of the median shaft (5) with a clearance just sufficient for the introduction of the median shaft (5) into the central cavity (22), the interior of the central cavity (22) having a complementary series of grooves (16) cooperating with the series of grooves (5a, 5b) on the median shaft (5) to form mechanical means (5a, 5b, 6) connecting the two rotors (2) to the shaft, a groove (6) of the complementary series being inserted between two grooves (5a, 5b) of the series on the median shaft (5).

13. The motor of claim 12, in which the central cavity (22) of the rotor (2) is on a ring (19) fastened to the associated rotor (2) by removable fastening means (23), the cavity (22) being extended by or housing a grooved sleeve (14).

14. The motor of claim 1, which integrates electronic control and power means on one longitudinal external wall of the housing (8), one of the two external circuits (7) housed in a longitudinal external wall of the housing (8) also providing cooling of the electronic control and power means.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other characteristics, purposes and advantages of the invention are described in greater detail below and with regard to the accompanying drawings which are provided by way of non-restrictive examples, and in which:

(2) FIG. 1 is a schematic representation of a view in longitudinal section of one embodiment of the motor according to the present invention,

(3) FIG. 2 is a schematic representation of a view in perspective of two rotors positioned on a common median shaft that is part of the motor or of the generator according to one embodiment of the present invention,

(4) FIG. 3 is a schematic representation of a view in perspective of a stator comprising teeth and windings mounted on a respective tooth, the stator being part of motor according to one embodiment of the present invention and incorporating a winding support snap-fitted on the tooth, two winding supports being shown in this FIG. 3,

(5) FIGS. 4 and 4a are schematic representations of a lateral view of a common median shaft supporting two rotors that are part of the motor or of the generator according to one embodiment of the present invention, the rotors not being positioned on the shaft in FIG. 4a,

(6) FIGS. 5 and 5a are schematic representations of a view in perspective of a common median shaft supporting the motor or the generator in one embodiment according to the present invention, a portion of the common median shaft being shown on a larger scale in FIG. 5a to more clearly show an offset between two series of grooves intended to serve as mechanical fastening means of the respective rotor,

(7) FIG. 6 is a schematic representation of a view in perspective of two rotors positioned on a common median shaft which is part of the motor or generator in accordance with one embodiment of the present invention, this figure showing in particular the complementary mechanical fastening means of a rotor on the common median shaft.

(8) The figures are presented by way of example and are not restrictive of the invention. They constitute schematic representations intended to facilitate an understanding of the invention and are not necessarily drawings to scale of practical applications. In particular, the dimensions of the different pieces are not representative of reality.

(9) In the following text, although all the figures illustrate a motor or generator with axial flux, the present invention also applies to a motor or a generator with radial flux.

(10) The adjective “longitudinal” must be understood with reference to the median shaft 5 that traverses the rotors 2.

DETAILED DESCRIPTION OF THE INVENTIONS

(11) In FIG. 3, a single tooth 3 is identified by a reference number although the description relating to this single tooth 3 also applies to all the other teeth 3 of the stator 3, 8. In FIG. 2, a single unitary magnet 11a is identified by a reference number for a magnet structure 11, although the description relating to this single unitary magnet 11a also applies to all the unitary magnets of the rotor 2. Moreover, in FIG. 2, a single magnet structure 11 is shown. The same is true for the grooves 5a, 5b on the median shaft and the grooves 6 on the rotors.

(12) With reference to all the figures and FIG. 1 in particular, the present invention relates to a permanent-magnet synchronous electromagnetic motor or generator comprising at least two rotors 2 and at least four stators 3, 8 with a housing 8.

(13) Each of the two rotors 2 comprises magnet structures 11 forming magnetic poles. The magnet structures 11 extend all the way around the at least one rotor 2 mounted so that it can rotate around a median shaft 5. Each of the four stators 3, 8 comprises windings 4.

(14) The motor or the generator comprises a cooling system 7, 7a comprising three circuits of a cooling fluid, advantageously water or water-based, although this specification is not restrictive.

(15) Two external circuits 7 are housed respectively in a longitudinal external wall of the housing 8 and are adjacent to an end stator 3, 8 to provide cooling of the associated end stator 3, 8.

(16) The cooling system 7, 7a comprises an intermediate circuit 7a located between the two innermost stators 3, 8, the median shaft 5 being common to the two rotors 2, the two rotors 2 being connected to the median shaft 5 by mechanical means 5a, 5b, 6. The reference number 5a refers to the mechanical means of the common median shaft 5 associated with a first rotor having complementary mechanical means 6 and reference 5b refers to the mechanical means of the common median shaft 5 associated with the second rotor.

(17) As shown in FIG. 1, the intermediate circuit 7a can be housed in an intermediate wall 8a, 8b of the housing 8 extending radially with respect to the common median shaft 5. This intermediate wall 8a, 8b contributes to the solidity of the housing 8 as well as to the housing of the intermediate circuit 7a of the cooling system 7, 7a, which is a dual function that achieves a saving of space and material.

(18) Still with reference primarily to FIG. 1, the intermediate wall 8a, 8b can comprise two portions 8a, 8b extending radially with respect to the common median shaft 5. Each portion 8a, 8b can be fastened respectively to one of the two innermost stators 3, 8 on the motor by removable fastening means 16. These removable fastening means 16 are in the form of fastening screws in FIG. 1.

(19) Reference number 13 indicates a ferrule that connects the longitudinal and exterior walls of the housing 8 to the intermediate wall 8a, 8b, a ferrule being provided on each side of the intermediate wall 8a, 8b. An air gap 12 exists between each stator 3, 8 and each rotor 2.

(20) As shown in FIG. 2 for a single magnet structure 11, each magnet structure 11 can be composed of a plurality of unitary magnets 11a in place of a single large magnet.

(21) The magnet structure 11 thus obtained can be in the form of a block with a rectangular or triangular cross-section.

(22) To prevent an axial displacement of the magnet structures 11, cover discs 10 can be located axially on each of the two opposite axial faces of each rotor 2 covering the magnet structures 11. This measure advantageously replaces the axial mechanical retaining means 5a, 6 and is made possible by the reduction of the amount of heat released by each magnet structure 11 compared to the amount of heat released by a corresponding large magnet. It was not unusual for the cover discs 10 to burn when used with large magnets, which is no longer the case with the unitary magnets 11a described in this preferential embodiment of the present invention.

(23) The cover discs 10 can be made of composite material. The magnet structures 11 can be coated in an external composite coating layer defining the external contour of each of the rotors 2. In two possible alternatives, the cover discs 10 can be coated in the external composite coating layer or located on a respective axial face of the external coating layer.

(24) A binding band 9 can surround the external coating layer on this external periphery farthest from the median shaft 5. The rotor 2 can therefore have a peripheral external ring forming its edge, the binding band 9 being located on a peripheral external ring making it possible to retain the unitary magnets 11a and the magnet structures 11 against a centrifugal force.

(25) The unitary magnets 11a can be constituted by elementary magnet blocks, which are advantageously hexagonal, with a mesh structure, the unitary magnets 11a being bonded by a resin that separates them or can each be inserted into a respective housing defined by one of the meshes of the mesh structure.

(26) Each block 11a has an elongated form penetrating lengthwise into its associated housing extending along the thickness of the magnet structure 11. Without being restrictive, the elongated block can be cylindrical or in the form of a polyhedron with at least one flat longitudinal face.

(27) The mesh structure can be in the form of a honeycomb. In this case, when this at least one mesh structure is in the form of a honeycomb, each block can have a longitudinal face with a hexagonal shape.

(28) In FIG. 2, the rotor 2 comprises branches 18 separating the adjacent magnet structures 11. The branches 18 can extend radially starting from the hub 18a forming the central part of the rotor 2. This arrangement is not restrictive and the separation between the magnet structures can be realized only by the external composite coating layer.

(29) With reference to FIG. 3 in particular, each stator 3, 8 comprises concentric windings 4 and a series of teeth 3 with windings 4 wound around each tooth, the teeth 3 being fastened to one another.

(30) As illustrated in this FIG. 3 in particular, each winding 4 can rest on the tooth 3 while surrounding at least partly a winding support 14. Each winding support 14 can comprise or be associated with snap-fitting means 15′ on a part 15 that cooperates with complementary snap-fitting means 3′ on a tooth 3 associated with the winding support 14 so that the winding support 14 is fastened to the associated tooth. This requires that at least a portion of the winding support 14 is inserted around the tooth 3.

(31) The snap fitting can be made directly between the winding support 14 at the tooth 3, in which case each winding support 14 carries snap-fitting means 15′, or between an intermediate piece 15 fastened to the winding support 14 and the tooth 3, in which case each winding support 14 is associated with snap-fitting means 15′ that the winding support 14 does not have. This latter case is illustrated in FIG. 3.

(32) As can be seen in particular in FIG. 3, the winding support 14 can comprise an intermediate portion 21 on which the winding 4 is wound. The winding support 14 can comprise a flat cover portion 20, which is advantageously dished, which is located farther from the associated tooth 3 in the fastening position of the winding support 14 on the tooth 3, being separated from the tooth 3 by the winding 4 and the intermediate portion 21.

(33) The flat cover portion 20 can have an external contour that covers at a distance at least one external contour facing the winding 4 and abutting against the external contour of the winding, whereby the winding support 14 can be in one piece or not. The cover portion 20 can abut an end of the winding 4 around the tooth 3 and around the intermediate portion 21.

(34) “At a distance” means that the flat cover portion 20 is not in contact against the face of the tooth 3 facing the winding 4 and “cover” means that the flat cover portion 20 conceals the surface of the tooth 3 facing the winding 4 when viewed head on. “Covering at least” means that the surface area of the flat cover portion 20 can be greater than the surface area of the tooth 3 facing the winding 4. There can be an empty space in the cover portion.

(35) In FIG. 3, the snap fitting is accomplished by an intermediate piece 15 fastened to the winding support 14. This intermediate piece 15 has snap-fitting shapes 15′ that cooperate with a respective groove 3′ as a complementary snap-fitting shape on the edges of the facing surface of the associated tooth 3.

(36) The windings 4 of the stators 3, 8 can advantageously be concentric and can be connected to the exterior of the motor in a terminal strip, either in series or in parallel.

(37) As shown more particularly in FIGS. 4, 4a, 5, 5a and 6, as mechanical fastening means 5a, 5b, 6 of each rotor 2 on the median shaft 5, the median shaft 5 can have a series of longitudinal grooves 5a, 5b on the median shaft 5 locally on each portion of the median shaft 5 intended to receive respectively one of the two rotors 2.

(38) A contour of a cavity 22 of the rotor 2 has a series of grooves 6, which either has the series of grooves 6 directly or has an interior part that has the series of grooves 6. These mechanical means 5a, 5b, 6 make possible a high degree of precision for the angular positioning in a radial plane of the rotors 2 fastened to the retaining shaft.

(39) Therefore, as shown in FIGS. 5 and 5a viewed in combination with FIG. 2, the magnet structures 11 on one of the two rotors 2 can be radially offset by a predetermined angle with respect to the magnet structures 11 on the other rotor 2, the mechanical means 5a, 5b, 6 being capable of precisely adjusting the offset of the magnet structures 11 of one rotor 2 with respect to the other rotor 2.

(40) As shown more particularly in FIG. 6, each rotor 2 can have a central cavity 22 which has an inside diameter, measured directly or with a spacer part 14 housed in the cavity 22 reducing its inside diameter, that equals the outside diameter of the median shaft 5 with a clearance that is just sufficient for the introduction of the median shaft 5 into the central cavity 22 with or without the spacer part 14.

(41) One edge of the central cavity 22 or of the spacer part 14 inserted into the cavity 22 can have on its internal periphery, as the second part, mechanical means 5a, 5b, 6 that are complementary to the first part, a series of grooves 6 that are complementary to the series of grooves 5a, 5b on the median shaft 5 and can cooperate with one another to form the mechanical means 5a, 5b, 6 connecting the two rotors 2 to the shaft.

(42) In the installed position of the rotor 2, a groove 6 of the complementary series can be inserted between two grooves of the series on the median shaft 5 and vice-versa.

(43) As illustrated in FIG. 5a, which is an enlarged detail of FIG. 5, a groove 5a of the first series of grooves of the median shaft 5 associated with a first rotor 2 is not aligned with a groove 5b of the second series of grooves of the median shaft associated with a second rotor. This can be seen by extending the two grooves 5a and 5b toward one another as indicated in FIG. 5a.

(44) As shown in particular in FIG. 6, the central cavity 22 is surrounded by or comprises a part in the form of a ring 19 which is fastened to the associated rotor 2 by removable fastening means 23. The cavity 22 can be extended by or house a grooved sleeve 14 fastened to the ring 19, whereby the sleeve can be one piece with the rim 19 or can be a separate part removably fastened to the ring 19.

(45) As a result of the presence of this grooved sleeve 14 between the edge of the cavity 22 and the median shaft 5, the inside diameter of the assembly formed by the cavity 22 and the grooved sleeve 14 is reduced and is essentially equivalent to the outside diameter of the median shaft 5.

(46) Although not shown in the figures and with reference to FIG. 1 for the elements shown in FIG. 1 and included in this embodiment, the motor can integrate electronic control and power means on one longitudinal extremity of the housing 8.

(47) One of the two external circuits 7 housed in a longitudinal external wall of the housing 8, located on the side of the motor where the electronic control means are advantageously housed in a casing that is continuous with the housing 8 of the motor or in the extension of the housing 8, can then also provide cooling of the electronic control and power means in addition to providing the cooling of an end stator 3, 8.