STATOR FOR A SUPERCONDUCTIVE MOTOR

Abstract

STATOR FOR A SUPERCONDUCTING MOTOR The invention relates to a stator (112) for a superconducting motor which comprises a cylindrical stator core (114) and traversed by orifices (116) extending parallel to a longitudinal axis (X) and distributed angularly and regularly around the longitudinal axis (X), and an armature (150) comprising a ring (152) made up of first strips (152a) arranged concentrically around each other, and for each orifice (116), of a bar (154) housed in the orifice (116) and made up of second strips (154a) stacked one on top of the other, where each second strip (154a) is intercalated and fixed between two first strips (152a) and where each first strip (152a) is intercalated and fixed between two second strips (154a). With such an arrangement, the manufacture and implementation of the stator are simplified. Fig. 4

Description

Title of the invention: STATOR FOR A SUPERCONDUCTING MOTOR Technical field

[0001] The present invention relates to the general field of superconducting motors and more particularly to superconducting motors comprising a stator made up of strips made of a superconducting material. STATE OF THE PRIOR ART

[0002] [Fig.6] shows a state-of-the-art superconducting motor 300, where the superconducting motor 300 is seen in section through a plane perpendicular to the longitudinal axis X of said superconducting motor 300.

[0003] The superconducting motor 300 comprises a rotor 302 which has a rotor core 304 made of a ferromagnetic material such as all iron alloys used for electrical machines. The rotor core 304 is cylindrical and coaxial with the longitudinal axis X and it has a central bore 306 in which a motor shaft 308 of said superconducting motor 300 is fitted and rigidly fixed. The motor shaft 308 is coaxial with the longitudinal axis X.

[0004] The rotor 302 also comprises permanent magnets 310 fixed to the rotor core 304 on the periphery of the latter. There are several permanent magnets 310 (here six in number) distributed angularly and regularly around the rotor core 304 and spaced from one another. Conventionally, the permanent magnets 310 are magnetized radially relative to the longitudinal axis X and in an alternating manner from one to the next.

[0005] The superconducting motor 300 comprises a stator 312 arranged outside the rotor 302 and comprising a stator core 314 made of a ferromagnetic material such as all iron alloys used for electrical machines. The stator core 314 takes a generally cylindrical shape coaxial with the longitudinal axis X.

[0006] At its cylindrical face which is oriented towards the rotor 302, the stator core 314 has slots 316 which here open towards the rotor 302. There are several slots 316 (here sixteen in number) distributed angularly and regularly around the rotor 302. The successive slots 316 are separated by a tooth 318. The slots 316 are arranged in pairs. A pair of slots 316 is formed of two non-successive slots 316. In particular, the slots 316 of a pair of slots 316 are separated by two slots 316 belonging to different pairs of slots 316.

[0007] For each pair of slots 316, the stator 312 comprises a coil 320. A coil 320 is wound in a pair of slots 316, around a plurality of teeth 318. Each coil 320 is made of a ribbon of superconducting material. In particular, the ribbon of superconducting material is wound radially to the longitudinal axis X in the slots 316 so as to form a coil 320. The coil 320 thus forms a stack of a superconducting ribbon in each slot 316. The superconducting ribbons are arranged perpendicular to the magnetic field lines which are inside the slots 316. Two slots 316 associated with the same coil 320 are separated by two slots 316 associated with two other coils 320. The coils 316 are thus intertwined with each other in the slots 316.

[0008] The rotor 302 and the stator 312 are conventionally housed in a motor housing 322 which is cylindrical and closed at its two ends by flanks, at least one of which is pierced with a central orifice allowing the passage of the motor shaft 308. The stator 312 is mounted fixed inside the motor housing 322 while the rotor 302 and the motor shaft 308 are mounted free to rotate inside the motor housing 322.

[0009] In operation, each coil 320 is electrically powered to generate a magnetic field that interacts with the permanent magnets 310 to drive them into rotation with the rotor 302 and the motor shaft 308.

[0010] The superconducting motor 300 comprises an inner cylinder 324 and an outer cylinder 326 which are coaxial with the longitudinal axis X.

[0011] The inner cylinder 324 is disposed between the rotor 302 and the stator 312, and the outer cylinder 326 is disposed around the stator 312 and inside the motor housing 322.

[0012] The inner cylinder 324 and the outer cylinder 326 extend between the two flanks to which they are hermetically fixed to delimit between them and the two flanks, a chamber 328 in which the stator 312 is housed and which can be evacuated.

[0013] In the context of a superconducting motor 300, the coils 320 must be cooled to improve their efficiency. To this end, for each slot 316, tubes 330 are arranged in the bottom of the slot 316 between the coil 320 housed in the slot 316 and the stator core 314. These tubes 330 are fluidically connected to a source of a refrigerant fluid. The refrigerant fluid is then injected into the tubes 330 to cool the coils 320.

[0014] Although such an arrangement gives good results, it is desirable to find a new arrangement which simplifies the manufacturing process of the stator and its installation in the superconducting motor. Statement of the invention

[0015] An object of the present invention is to provide a superconducting motor which comprises a stator consisting of interlaced strips made of a superconducting material.

[0016] For this purpose, a stator is proposed for a superconducting motor comprising a rotor which can rotate about a longitudinal axis, where the stator is intended to be arranged outside the rotor and comprises:

[0017] - a cylindrical stator core, made of a ferromagnetic material, where the core of stator is crossed by orifices extending parallel to the longitudinal axis and distributed angularly and regularly around the longitudinal axis, and

[0018] - a frame comprising a ring made up of first strips made in a superconducting material and arranged concentrically around each other, and for each orifice, a bar housed in the orifice and consisting of second strips made of a superconducting material and stacked on top of each other, where each second strip is inserted and fixed between two first strips and where each first strip is inserted and fixed between two second strips.

[0019] With such an arrangement, the manufacture and implementation of the stator are simplified.

[0020] Advantageously, the stator comprises a thermal ring arranged around the ring and in which is housed a cooling pipe intended to be fluidically connected to a refrigerant circuit and for each bar, a thermal strip arranged between the bar and the stator core and secured to the thermal ring.

[0021] Advantageously, each attachment of a second strip to a first strip is carried out by welding.

[0022] The invention also proposes a superconducting motor comprising a rotor with a rotor core carrying permanent magnets and movable in rotation around the longitudinal axis and a stator according to one of the preceding variants, where the stator is arranged outside the rotor.

[0023] The invention also proposes an aircraft comprising at least one superconducting engine according to the previous variant.

[0024] Advantageously, the aircraft comprises a refrigerant circuit comprising a source of refrigerant fluid, said source of refrigerant fluid being fluidically connected to each cooling pipe. Brief description of the drawings

[0025] The above-mentioned features of the invention, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the attached drawings, among which:

[0026] [Fig-1] is a sectional view of a superconducting motor according to the invention,

[0027] [Fig.2] is a perspective view of an armature for a stator of a supra motor conductor according to the invention,

[0028] [Fig.3] is an enlargement of detail II of [Fig.l],

[0029] [Fig.4] is a perspective view of the stator for the superconducting motor according to the invention,

[0030] [Fig.5] is a sectional view through a radial plane IV of the stator of [Fig.3], and

[0031] [Fig.6] is a sectional view of a state-of-the-art superconducting motor.

[0032] DETAILED DESCRIPTION OF EMBODIMENTS

[0033] [Fig.l] shows a superconducting motor 100 according to the invention in section through a plane perpendicular to the longitudinal axis X of the superconducting motor 100. The superconducting motor 100 has generally the same structure as the superconducting motor 300 of the prior art.

[0034] The superconducting motor 100 comprises a rotor 102 which is rotatable about the longitudinal axis X and which has a rotor core 104 made of a ferromagnetic material such as all iron alloys used for electrical machines. The rotor core 104 is cylindrical and coaxial with the longitudinal axis X and it has a central bore 106 in which a motor shaft 108 of said superconducting motor 100 is fitted and rigidly fixed. The motor shaft 108 is coaxial with the longitudinal axis X.

[0035] The rotor 102 also comprises permanent magnets 110 fixed to the rotor core 104 on the periphery of the latter. There are several permanent magnets 110 (here six in number) distributed angularly and regularly around the rotor core 104 and spaced from one another. Conventionally, the permanent magnets 110 are magnetized radially relative to the longitudinal axis X and in an alternating north-south manner from one to the other.

[0036] The superconducting motor 100 comprises a stator 112 arranged outside the rotor 102 and comprising a cylindrical stator core 114 coaxial with the longitudinal axis X and therefore arranged outside the rotor 102.

[0037] The stator core 114 is made of a ferromagnetic material such as all iron alloys used for electrical machines.

[0038] The stator core 114 is crossed by an even number of orifices 116 (here sixteen in number) which cross the stator core 114 parallel to the longitudinal axis X. According to another embodiment not shown, it is possible to have an odd number of orifices 116.

[0039] In the embodiment of the invention presented here, each orifice 116 opens towards the rotor 102, at an inner surface of the stator core 114 oriented towards the longitudinal axis X, but in another embodiment not shown, the orifices 116 can be partially closed at the inner surface of the stator core 114.

[0040] The orifices 116 are distributed angularly and regularly around the rotor 102 and therefore of the longitudinal axis X.

[0041] The superconducting motor 100 also comprises an armature 150 which is shown alone in [Fig.2] and with the stator core 114 in [Fig.4].

[0042] The frame 150 comprises a ring 152 and for each orifice 116, a bar 154 housed in the orifice 116 and secured to the ring 152. In Figs. 2 to 4, there are only six bars 154 instead of the sixteen present in [Fig. 1] for reasons of simplification of the drawings.

[0043] [Fig. 3] shows an enlargement of a junction zone between the ring 152 and a bar 154.

[0044] The ring 152 consists of first strips 152a which are made of a superconducting material and which are arranged concentrically around each other and coaxially with the longitudinal axis X.

[0045] In the same way, each bar 154 extends parallel to the longitudinal axis X and is made up of second strips 154a which are made of a superconducting material and which are stacked on top of each other in a radial direction relative to the longitudinal axis X. The section of each second strip 154a is thus oriented orthoradially around the longitudinal axis X.

[0046] At the attachment zone between a bar 154 and the ring 152, each second strip 154a is interposed and fixed between two first strips 152a and each first strip 152a is interposed and fixed between two second strips 154a.

[0047] The armature 150 thus forms a single element which can be easily put in place in the superconducting motor 100 by inserting each arm 154 into the corresponding orifice 116.

[0048] When inserting the bars 154 into the orifices 116, the ring 152 comes against a face of the stator core 114 and conventionally, each bar 154 is electrically powered by an electrical power supply system.

[0049] Each attachment of a second strip 154a to a first strip 152a is carried out by welding, which makes it possible, with the alternation of the first strips 152a and the second strips 154a, to reduce the junction resistances and the losses due to the welding.

[0050] To limit the temperature increase in the superconducting motor 100, a cooling system is put in place and [Fig. 3] shows a particular embodiment of such a cooling system. To this end, the stator 112 comprises a thermal ring 170 arranged and fixed around the ring 152 and therefore around the rotor 102. In the thermal ring 170 is housed a cooling pipe 170a. The cooling pipe 170a is also fluidically connected to a refrigerant circuit in which a heat transfer fluid circulates. The heat transfer fluid then takes on calories by passing through the cooling pipe 170a and joins the refrigerant circuit where the calories are evacuated.

[0051] The cooling pipe 170a extends around the ring 152 and has first and second ends, where the first end is fluidically connected to an outlet of the refrigerant circuit and where the second end is fluidically connected to an inlet of the refrigerant circuit. The cooling pipe 170a and the refrigerant circuit thus form a loop in which the heat transfer fluid circulates.

[0052] The refrigerant circuit comprises, among other things, a source of heat transfer fluid, a pump which sets the heat transfer fluid in motion and a heat exchanger which is associated with a cold source to evacuate the calories from the heat transfer fluid.

[0053] To recover the calories from the arms 154 and transmit them to the heat transfer fluid, for each bar 154, the stator 112 comprises a thermal strip 172 arranged between the bar 154 and the stator core 114 and secured to the thermal ring 170.

[0054] Each thermal strip 172 and the thermal ring 170 are made of materials having high thermal conductivities.

[0055] The thermal strip 172 is arranged against the second outermost strip 154a and is therefore located at the bottom of the orifice 116, i.e. on the side opposite the rotor 102.

[0056] In the embodiment of the invention presented here, the rotor 102 and the stator 112 are housed in a motor housing 122 which is cylindrical and closed at its two ends by flanks, at least one of which is pierced with a central orifice allowing the passage of the motor shaft 108. The stator 112 is mounted fixed inside the motor housing 122 while the rotor 102 and the motor shaft 108 are mounted free to rotate inside the motor housing 122.

[0057] In operation, each bar 154 is electrically powered by an alternating current to generate a magnetic field which interacts with the permanent magnets 110 to drive them in rotation with the rotor 102 and the motor shaft 108. For each bar 154, the electrical power supply is provided from the free ends of said bars 154, that is to say at the ends located opposite the ring 152.

[0058] As with the prior art superconducting motor 300, the superconducting motor 100, in the embodiment of the invention presented here, comprises an inner cylinder 124 and an outer cylinder 126 which are coaxial with the longitudinal axis X.

[0059] The inner cylinder 124 is disposed between the rotor 102 and the stator 112 and the outer cylinder 126 is disposed around the stator 112 and inside the motor housing 122.

[0060] The inner cylinder 124 and the outer cylinder 126 extend between the two sides to which they are hermetically fixed to delimit between them (the two inner cylinders 124 and outer 126) and the two sides, a chamber 128 in which is housed the stator 112 and which can be evacuated.

[0061] In use in an aircraft, said aircraft comprises at least one superconducting motor 100 according to the invention.

[0062] With the cooling system, the aircraft then comprises the refrigerant circuit with the source of heat transfer fluid which is thus fluidically connected to each cooling pipe 170a.

Claims

Claims

1. Stator (112) for a superconducting motor (100) comprising a rotor (102) rotatable about a longitudinal axis (X), where the stator (112) is intended to be arranged outside the rotor (102) and comprises: - a cylindrical stator core (114), made of a ferromagnetic material, where the stator core (114) is traversed by orifices (116) extending parallel to the longitudinal axis (X) and distributed angularly and regularly around the longitudinal axis (X), and - an armature (150) comprising a ring (152) consisting of first strips (152a) made of a superconducting material and arranged concentrically around each other, and for each orifice (116), a bar (154) housed in the orifice (116) and consisting of second strips (154a) made of a superconducting material and stacked on top of each other,wherein each second strip (154a) is sandwiched and secured between two first strips (152a) and wherein each first strip (152a) is sandwiched and secured between two second strips (154a).,

2. Stator (112) according to claim 1, characterized in that it comprises a thermal ring (170) arranged around the ring (152) and in which is housed a cooling pipe (170a) intended to be fluidically connected to a refrigerant circuit and for each bar (154), a thermal strip (172) arranged between the bar (154) and the stator core (114) and integral with the thermal ring (170).

3. Stator (112) according to one of claims 1 or 2, characterized in that each attachment of a second strip (154a) to a first strip (152a) is carried out by welding.

4. Superconducting motor (100) comprising a rotor (102) with a rotor core (104) carrying permanent magnets (110) and rotatable about the longitudinal axis (X) and a stator (112) according to one of the preceding claims, wherein the stator (112) is arranged outside the rotor (102).

5. Aircraft comprising at least one superconducting engine (100) according to the preceding claim.

6. Aircraft according to the preceding claim, dependent on claim 2, characterized in that said aircraft comprises a refrigerant circuit comprising a source of refrigerant fluid, said source of refrigerant fluid being fluidically connected to each pipe of cooling (170a).

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