Magnetic Calorie Generator

Abstract

The invention relates to a magnetocaloric generator (1) comprising a set of porous active elements (2) based on MCM material and a magnetic device (3). The magnetic device (3) comprises two superimposed magnetic rotors, an external magnetic rotor (4) and an internal magnetic rotor (5), defining an air gap (E) between them and comprising one and the same number of magnetic poles (PM). The set of active elements (2) comprises a stator (30) arranged in said air gap (E). The active elements (2), extending axially in said stator (30), allow a bidirectional axial circulation of a heat transfer fluid between the hot end (EC) and the cold end (EF) of said generator. The external magnetic rotor (4) is advantageously coupled on the one hand to an electric machine (9) by a mechanical coupling and on the other hand to said internal magnetic rotor (5) by a magnetic coupling, whereby said rotors move in one and the same rotational sense and are magnetically synchronized.

Description

[Technical field]

[0001] The present invention relates to a magnetocaloric generator comprising at least one set of active elements based on a magnetocaloric material (MCM) and a magnetic device arranged movably with respect to the set of active elements, said magnetic device comprising two superimposed magnetic rotors, i.e. an outer magnetic rotor and an inner magnetic rotor, defining an air gap between them, said outer magnetic rotor and said inner magnetic rotor having one and the same number of magnetic poles, said set of active elements constituting a stator arranged in said air gap, said active elements extending longitudinally within said stator between a hot end and a cold end of the generator. [Background technology]

[0002] The technology of ambient magnetic refrigeration has been known for more than 40 years and its advantages in terms of energy efficiency and reduced environmental impact over conventional technologies based on the compression and expansion of refrigerant gases are known, as well as its limitations in terms of its heat output or energy conversion. All research carried out in this field since then tends to improve the performance of magnetocaloric generators by exploiting the parameters of the various components, such as the strength and quality of the magnetic field, the performance of the magnetocaloric material of the active element, the heat exchange surface between the heat transfer fluid and the active element, the performance of the heat exchanger, etc.

[0003] Today, developments concern the optimization of these generators with the expectation that, on the one hand, they can be manufactured in large quantities and, on the other hand, that they can be guaranteed a significant service life. In addition to having to reach a commercially interesting energy efficiency, these generators must have a relatively small size or dimensions so that they can be integrated into commercial applications that have size limitations.

[0004] The patents WO 2004 / 023363 and WO 2004 / 023664 belonging to the applicant give recognition of the technological developments already applied to magnetocaloric generators, which can be further improved.

[0005] In the patent document 3, a Halbach-type magnetic assembly for a magnetic refrigeration generator is described. It comprises two coaxial magnetic rotors, an outer rotor and an inner rotor, separated by an air gap, in which active elements in the form of magnetocaloric material sections are arranged. The rotors are driven synchronously and in opposite directions by a motor and a mechanical drive. The counter-rotation drive of the rotors makes it possible to generate a magnetic field change that is applied to the active elements located in the air gap. However, this principle does not allow the potential energy of the magnets of the rotors to be utilized. In fact, over a small part of the rotation, the rotors are neither in phase nor in phase adjustment, which, from the point of view of the MCM, results in a long and inoperative transition phase, which is detrimental to the performance of the generator. If the magnets are in phase opposition for half of the effective cycle time, the potential energy of the magnets is not utilized at all, and as a result, the magnets are undervalued. Moreover, this principle is the source of eddy currents in the structure of the magnetic rotor, which must be managed, and which put the magnets at risk of demagnetization by exceeding their coercive field.

[0006] In the patent application US 2005 / 0133636 A1 a composite matrix based on magnetocaloric materials is described. These materials are in the form of particles bound by a coating based on another non-magnetocaloric material, such as nickel. The coated particles together define cavities for the circulation of a liquid. The result is an amorphous porous matrix, i.e. a random and irregular matrix, which inevitably generates load losses, which impair the performance of the magnetic refrigeration generator. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2009 / 087310 Brochure [Patent Document 2] International Publication No. 2015 / 079313 Brochure [Patent Document 3] China Patent Application Publication No. 113314292 [Patent Document 4] International Publication No. 2019 / 110193 Brochure Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to propose a new generation of magnetic calorific generators, which aims to optimize the performance of the generator, maximize the strength and magnetic field change applied to the active element, optimize the response of said active element, optimize the utilization of the magnetic energy (BHmax) of the magnet, reduce the load losses and friction sources, avoid eddy currents, reduce the energy consumption and individualize the technical features of the generator to achieve the targeted objectives, thereby addressing a wide range of applications such as heating, cooling, air conditioning, reversible heat pumps, thermomagnetic motors, etc. It further relates to reversible converters that allow the pumping of thermal energy from a cold source to a hot source using mechanical and / or electrical work or the transformation of thermal energy in the form of a temperature difference of mechanical and / or electrical work, in which case the transformation between mechanical and electrical energy is ensured by conventional electromagnetic machines such as alternators, dynamos, electric motors, etc. [Means for solving the problem]

[0009] In light of this, the present invention relates to a generator of the type indicated in the preamble, characterized in that one of said external or internal magnetic rotors is coupled, on the one hand, to an electric machine by a mechanical coupling and, on the other hand, to the other of said internal or external magnetic rotors by a magnetic coupling, whereby said rotors move in one and the same direction and are magnetically synchronized.

[0010] In a preferred embodiment of the invention, the generator has a cylindrical shape, the external and internal magnetic rotors are concentric about their axis of rotation, and the stator has an annular shape concentric with the external and internal magnetic rotors.

[0011] The external magnetic rotor is preferably coupled to the electric machine, in which case the external magnetic rotor comprises a peripheral toothed ring and the mechanical coupling between the external magnetic rotor and the electric machine comprises a toothed belt transmission meshing with the toothed ring.

[0012] In a preferred embodiment of the invention, the generator comprises at least means for rotatably guiding the external magnetic rotor and the internal magnetic rotor carried by a casing, the means for rotatably guiding the external magnetic rotor comprising a peripheral guide member attached to an end of the external magnetic rotor and arranged to circulate on a guide path belonging to the casing.

[0013] The guide members are advantageously mounted on the outer magnetic rotor in peripheral sectors located outside the poles, and the guide paths are advantageously provided on a guide ring added to the casing, said guide ring being capable of being made of a material of greater hardness than the hardness of the material of the casing.

[0014] Certainly advantageously, the magnetic device is of modular construction and comprises an assembly of at least two basic modules stacked longitudinally, each basic module comprising a portion of the outer magnetic rotor and a portion of the inner magnetic rotor, the number of basic modules defining the length of the magnetic device and being determined depending on the target power and / or temperature difference of the generator.

[0015] The basic modules preferably include complementary interlocking features arranged on the one hand to centre the basic modules about the axis of rotation and to index the angular position of the basic modules relative to each other.

[0016] According to a variant embodiment of the invention, the magnetic device may comprise a magnetic field homogenizing device facing the air gap and superimposed on the magnetic poles of the external magnetic rotor and / or the internal magnetic rotor.

[0017] In a preferred embodiment of the invention, the active elements are porous and are traversed by a heat transfer circuit allowing the alternative circulation of a heat transfer fluid from the hot end to the cold end in a first working cycle of the generator and conversely from the cold end to the hot end in a second working cycle, the direction of circulation of the heat transfer fluid being advantageously perpendicular to the direction of the magnetic field lines generated by the poles of the magnetic device.

[0018] Preferably, the number of active elements of the assembly is a multiple of the number of poles of the magnetic device, and the active elements are arranged side by side on the circumference of the stator.

[0019] Each active element may comprise a longitudinal material carrier housed in the stator, the material carrier then having a cross section chosen among square, rectangular, trapezoidal, the length of the material carrier being advantageously determined depending on the length of the magnetic device and the targeted power, efficacy and / or temperature difference of the generator.

[0020] In a preferred embodiment of the invention, the material carrier of each active element comprises an inner housing configured to receive at least one MCM and at each of the ends of the material carrier at least one fluid connector configured to connect said active element to said heat transfer circuit. The material carrier may further comprise at least one distributor in each end region between said fluid connector and said inner housing.

[0021] The active elements may comprise at least one porous MCM block in amorphous form of regular material strips or structures spaced apart from one another, oriented parallel to the longitudinal axis of the material carrier, the spaces advantageously constituting a set of longitudinal channels allowing bidirectional circulation of the heat transfer fluid through each active element.

[0022] The active element may comprise one or more porous MCM blocks of one and the same MCM, or of different MCMs separated from one another by bond wedges, or of different MCM compositions dispensed and organized to obtain variable Curie temperatures, the different MCMs or MCM compositions preferably being stored or sequenced according to increasing or decreasing Curie temperatures that evolve in a stepwise or continuous manner.

[0023] The invention and its advantages will best emerge in the following description of some embodiments, given as non-limiting examples, with reference to the attached drawings, in which: [Brief description of the drawings]

[0024] [Figure 1] 1 is a perspective view of a magnetocaloric generator according to the invention, represented by its magnetic device and its rotary drive system; [Diagram 2] 3 is a perspective view of a part of a magnetic device belonging to a generator according to the invention and of a support for an active element; [Diagram 3] 1 is a side view of a generator according to the invention, represented by its magnetic device and its active element; [Figure 4] FIG. 1 is a perspective view of the magnetic device of a generator according to the invention, consisting of an assembly of two basic modules. [Diagram 5] FIG. 5 is an exploded perspective view of the basic module of FIG. 4. [Figure 6] FIG. 4 is a simplified side view, similar to FIG. 3, of a generator according to a variant of the invention. [Figure 7] FIG. 2 shows an exploded view of the active elements of the generator according to the invention. [Figure 8] FIG. 8 is a longitudinal sectional view of the active element of FIG. [Figure 9] FIG. 1 is a perspective view of a generator according to the invention, seen from an axial end, streamlined and equipped with a system for controlling the heat transfer circuits; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In the illustrated embodiment examples, identical elements or parts have the same reference numbers. Moreover, terms having a relative meaning, such as vertical, horizontal, right, left, front, rear, top, bottom, etc., must be interpreted as they are represented in the figures, under normal conditions of use of the invention. The axes X, Y, and Z are themselves defined by an orthonormal system shown in FIG. 1. Moreover, the geometric positions indicated in the present specification and claims, such as "vertical", "parallel", "symmetrical", etc., are not limited to those defined as geometric in the strict sense, but extend to geometric positions that are close, i.e., accepting a certain tolerance in the art, without affecting the results obtained. This tolerance is introduced, in particular, by the adverb "substantially", which is not necessarily repeated before each adjective.

[0026] With reference to the figures, a magnetocaloric generator 1 according to the invention, hereinafter also referred to as "generator 1", comprises a set of MCM-based active elements 2 and a magnetic device 3 that are movable relative to one another. In the illustrated example of a preferred embodiment of the invention, the magnetic device 3 is movable with respect to the fixed set of active elements 2, which allows the heat transfer fluid system to be significantly simplified. The generator 1 further comprises a heat transfer circuit for thermally coupling the active elements to at least one device or one external application (not shown), for example via at least one heat exchanger (not shown), as described in the above-mentioned publications of the applicant. The heat transfer circuit may comprise a heat transfer fluid or a solid heat transfer fluid (not shown) as described in WO 2022 / 112391. The invention relates in particular to the pumping of heat from a cold source to a hot source in order to generate heat and / or cooling from mechanical or electrical energy, by using the transition properties of the magnetic phase of magnetocaloric materials, hereinafter referred to as MCM, under the effect of a magnetic field change in the vicinity of their transition temperature, also called Curie temperature or critical temperature (Tc). The invention also relates to the conversion of available thermal energy in the form of a temperature difference into mechanical or electrical energy, by using the same properties of MCM materials under the effect of a temperature change. The generator 1 of the invention thus constitutes an energy converter that can be reversible, i.e. that can operate according to two preliminary operating modes depending on the input energy.

[0027] In the illustrated example, the generator 1 is represented with a cylindrical shape, the magnetic device 3 comprising or formed from two superimposed magnetic rotors concentric about a rotation axis A along X, the outer magnetic rotor 4 and the inner magnetic rotor 5 together defining an annular interval called air gap E. The outer magnetic rotor 4 and the inner magnetic rotor 5 comprise one and the same number of magnetic poles PM, at least two poles PM (FIGS. 3 and 6), four poles PM (FIGS. 1, 4, 5) or, if necessary, more than four poles PM. The poles PM of each rotor 4, 5 are regularly distributed on the circumference of each of the rotors 4, 5, each extending over an angular sector of the same value and occupying a portion that corresponds substantially to half the circumference of the rotors 4, 5. The remaining half of the circumference of the rotors 4, 5 is occupied by a vacuum area (outside the magnetic field) (FIGS. 1 and 6) or includes a non-magnetic, thermally and / or electrically insulating material (FIG. 3). Furthermore, the magnetic poles PM of the two rotors 4, 5 are arranged in pairs to generate a continuity of magnetic field lines in each pair of magnetic poles PM of the outer magnetic rotor 4 and the inner magnetic rotor 5. In this way, the magnetic field lines are concentrated in the air gap E between each pair of magnetic poles PM, thereby forming an area under the magnetic field. This magnetic field concentration has the effect of maximizing the strength of the magnetic field in the area under the magnetic field and maximizing the change of the magnetic field between the area under the magnetic field and the area outside the magnetic field. Each magnetic pole PM comprises or is formed from one or more magnetic generators 6, 7, such as permanent magnets, electromagnets, superconductors, or any other suitable magnetic generator. If each magnetic pole PM comprises or is formed from several magnetic generators 6, 7, as shown in Figures 1, 3, 6, each magnetic pole PM is coupled to each other to form a continuous and uninterrupted magnetic pole PM.

[0028] In a variant of the embodiment shown in FIG. 6, the magnetic device 3 further comprises a field homogenizing device 8 arranged to homogenize and regularize the magnetic field generated by the magnetic poles PM and, correlatively, to increase the magnetic performance of the magnetic poles PM and therefore the effectiveness and the power of the generator 1. For example, the magnetic performance of the magnetic poles PM can be increased by at least 30% via the homogenizing device 8, but this value is not limiting. In the illustrated example, the field homogenizing device 8 is represented in the form of a sheet or in the form of a plate arranged to cover each end of the magnetic poles PM of the external magnetic rotor 4 and / or of the internal magnetic rotor 5 facing the air gap E. The field homogenizing device 8 can have any other shape advantageous for homogenizing the magnetic field in the area under the magnetic field in the air gap E, such as a prismatic shape, without limiting the shape. The homogenizing device 8 is profiled to approximate the shape of the profile of the magnetic poles PM and / or of the active element 2. The homogenizing device 8 can be added to the ends of the magnetic poles PM by gluing or by any other obviously equivalent fastening method. The homogenizing device 8 can be made of low carbon steel, pure iron, and any other ferromagnetic material. By way of example, the homogenizing device 8 can have a thickness between 2 mm and 5 mm, which may or may not be constant, and this value range is not limiting.

[0029] The external magnetic rotor 4 and the internal magnetic rotor 5 are coupled to each other and rotate synchronously around the axis of rotation A in one and the same direction of rotation. They may be coupled by a mechanical power transmission such as a gear train, a belt and pulley system, a chain and pinion system. If each rotor is coupled to a motorization, they may be coupled by an electronic power transmission. Preferably, they are magnetically coupled, i.e. in contact, so that efficiency losses due to friction can be avoided. The technical effect of this principle of driving the two rotors makes it possible to exploit the maximum potential energy (BHmax) of the magnets forming the magnetic poles at each moment. The magnetic field lines follow a continuous path that is as uniform and concentrated as possible, looping continuously over the internal rotor 5 and the external rotor 4, which rotate synchronously with respect to the active element 2 located in the air gap E. The rotors 4 and 5 are magnetically synchronous, since they do not move with each other due to their magnetic coupling. As a result, the magnetic device 3 becomes the seat of a magnetic field which is stationary relative to itself and rotates relative to the fixed stator 30, thereby producing an alternation between areas under and outside the magnetic field, even during transition phases which are as short as possible.

[0030] In a preferred embodiment of the invention, the external magnetic rotor 4 is rotated by an electric machine 9, which itself drives the internal magnetic rotor 5 by magnetic coupling, as shown in FIG. 1. Naturally, the reverse configuration, i.e. the internal magnetic rotor 5 is driven by an electric machine 9, which itself drives the external magnetic rotor 4 by magnetic coupling, may be appropriate. However, since the mechanical inertia of the external magnetic rotor 4 is greater than that of the internal magnetic rotor 5, the effectiveness of the magnetic coupling is clearly greater in the example shown. In this way, it is possible to limit the vibration phenomena that occur when driving the internal magnetic rotor 5 by magnetic coupling with an external mechanical drive.

[0031] The electric machine 9 may be constituted by any type of motor or any type of alternator, depending on the operating mode of the magnetic heat generator. In the illustrated example, the electric machine 9 is coupled to the external magnetic rotor 4 by a mechanical power transmission. Moreover, in the illustrated example, this mechanical power transmission preferably comprises a toothed belt 10 which meshes with a toothed belt 11 provided around the external magnetic rotor 4. Naturally, any other type of mechanical power transmission may be suitable, but the power transmission by toothed belt 10 has the advantage of being precise, reliable and quiet. Furthermore, since the reduction ratio between the toothed pulley 12 at the outlet of the electric machine 9 and the toothed belt 11 of the external magnetic rotor 4 is rather large, it is possible to remove the reducer between the electric machine 9 and the external magnetic rotor 4, which also improves the energy efficiency of the generator 1. In this way, the electric machine 9 can be optimally dimensioned to reach the optimal operating point of the generator 1.

[0032] The two rotors 4, 5 are rotatably guided about their axis A by guiding means carried by the casing C (Fig. 9). The two rotors 4, 5 are furthermore stopped in translation along X by any suitable blocking means (not shown). The internal magnetic rotor 5 can be rotatably guided by any known means, for example by two bearings 13 provided in its end area (Fig. 1). The external magnetic rotor 4 is itself rotatably guided by a series of guiding elements 14, preferably fixed to the ends of said rotor, arranged around its circumference and small compared to the average diameter of said rotor. In the illustrated example, the guiding elements 14 are represented in the form of rotating rollers arranged to circulate on guiding paths belonging to the casing C (Fig. 9). This solution is particularly advantageous since it allows one rotational guidance of the external magnetic rotor 4 per bearing and is therefore frictionless, effective, reliable, does not generate heat and therefore does not consume energy. Moreover, this solution is economical, considering the low cost of this type of guiding elements 14, which are parts available on the market. This solution is also universal, since it is suitable for all sizes of generators 1 and therefore for all diameters of the external magnetic rotor 4. However, this example is not limiting and any other equivalent or suitable type of guiding members, such as low friction coefficient runners, may be suitable. Furthermore, the peripheral arrangement of the guiding members 14 makes it possible to free up the entire central part of the generator 1, in particular its hot end EC and cold end EF, in order to house the heat transfer circuits there (FIG. 9). This arrangement allows the generator 1 to be made more compact.

[0033] The guide elements 14 can be regularly arranged around the circumference of the external magnetic rotor 4 (FIG. 1) or preferably outside the poles PM (FIGS. 2 and 3), which facilitates their mounting, ensures their friction-free operation and limits eddy currents inside them. The guide elements 14 can be mounted on flanges 16 added to the ends of the external magnetic rotor 4. The guide paths can be provided directly on the casing C or in a guide ring 15 added to the casing C. The guide ring 15 can thus be made of a material different from that of the casing C, in particular a material whose hardness is greater than that of the material of the casing C, such as a stainless steel guide ring for an aluminum casing C, this example is not limiting and it is possible to optimize the choice of raw material and the cost depending on its function. The arrangement of the guide elements 14 makes it possible to balance the radial forces, but the guide paths or the guide ring 15 can be configured to form a translation stop along X of the external magnetic rotor 4, with or without friction.

[0034] The magnetic device 3 can be of monolithic or preferably modular construction according to the variants of the illustrated embodiment. The modular construction allows to facilitate and streamline the manufacture of the generator 1 to meet the targeted specifications and applications, making it possible to lengthen the generator 1 without increasing its diameter. With reference to figures 1, 2, 4 and 5, the magnetic device 3 comprises an assembly of at least two axially superimposed basic modules 17, the number of basic modules 17 of the magnetic device 3 determining its length, which is itself determined in particular depending on the targeted power and / or temperature difference of the generator 1.

[0035] Each basic module 17 comprises a part of the outer magnetic rotor 4 and a part of the inner magnetic rotor 5. Naturally, since the two rotors are physically separate parts, the basic modules 17 of each rotor are managed separately. More specifically, Figure 4 shows the assembly of two superimposed basic modules 17 of the two rotors 4, 5 represented without the magnets 6, 7.

[0036] FIG. 5 shows the basic modules 17, showing only the external magnetic rotor 4 represented without the magnets 6. Each basic module 17 comprises a magnetic shell 18 of the external magnetic rotor 4, which can be made of one single piece or of several pieces, such as a stack of cut paper, and is optionally electrically insulated to prevent the formation of eddy currents that would result from the changes in the magnetic currents caused by the active element 2. In the example shown, the magnetic shell 18 is composed of a number of elementary magnetic sheets 19, which are a few millimeters to a few centimeters, for example between 0.5 mm and 10 mm, although these values ​​are not limiting. The elementary magnetic sheets 19 are cut or punched, stacked axially and assembled to one another by fastening members (not shown) through orifices 20 provided in the corresponding lugs 21. Of course, any other equivalent fastening means may be suitable. The method of production by stacking the elementary magnetic sheets 19 allows the optimization of the production tools and the amount of raw material used, allowing more flexibility in the design of the magnetic assembly 3 and reducing the overall production costs. In this way, the axial length of the basic module 17 about the axis X can be adjusted as required.

[0037] The basic modules 17 of each rotor further comprise complementary interlocking shapes arranged on the one hand to center the basic modules 17 with respect to the axis of rotation A and to index the angular position of the basic modules 17 with respect to each other. In the example shown in figures 4 and 5, each basic module 17 of the external magnetic rotor 4 is surrounded by two end magnetic sheets 22 which may have a thickness greater than that of the basic magnetic sheet 19 and which comprise complementary interlocking shapes. These complementary interlocking shapes comprise, on one of the end magnetic sheets 22 of each basic module 17, a male interlocking shape in the form of an axially projecting ridge 23 rotated towards the outside of said module, divided into four angular sectors regularly distributed between the magnetic poles PM of the external magnetic rotor 4. Correspondingly, the complementary interlocking shape comprises, on the opposite end magnetic sheet 22 of each basic module 17, a female interlocking shape in the form of an axially projecting groove 24 rotated towards the inside of said module, divided into four angular sectors regularly distributed between the magnetic poles PM of the external magnetic rotor 4. Of course, any other equivalent complementary interlocking features may be suitable, including any other centering and indexing means.

[0038] The basic modules 17, which form all or part of the magnetic device 3, are further assembled to one another by fastening members (not shown), such as threaded rods, bolts, tie rods, screws, etc., through orifices 25 provided in corresponding lugs 26 (Fig. 4). Naturally, any other equivalent fastening means may be suitable, such as welded points or welded lines between the basic modules. For ease of installation, the basic modules 17 may be assembled to one another in groups of two, which may then themselves be assembled to one another by intermediate flanges, as shown in Fig. 1. Any other assembly method may also be suitable.

[0039] The basic modules of the internal magnetic rotor 5 also have complementary interlocking, centering and indexing features and fixing means, not shown. As an example, there may be indexing pins and through holes for screws, which allow both fixing and holding the basic modules in position relative to each other. Any other equivalent complementary interlocking features and any other equivalent fixing means may also be suitable.

[0040] More specifically, with reference to Figures 2, 3 and 6, the set of active elements 2 of the generator 1 of the invention comprises or is formed from a fixed annular stator 30, centered on an axis of rotation A along X, disposed in the air gap E between the external magnetic rotor 4 and the internal magnetic rotor 5. The active elements 2 extend longitudinally within the stator 30 between a hot end EC and a cold end EF of the generator 1, and are symbolically represented in Figures 2 and 7. The active elements 2 are porous and pass said magnetocalorically passive heat transfer fluid through heat transfer circuits that allow alternative axial circulation along X by the heat transfer fluid from said hot end EC to said cold end EF and vice versa, respectively, to carry out a magneto-thermodynamic cycle within the generator 1.

[0041] As a result, the axial circulation along X of the heat transfer fluid is perpendicular to the radial orientation of the magnetic field lines generated by the magnetic poles PM of the magnetic device 3. This arrangement is particularly advantageous since it enables the active element 2 to perform a magneto-thermodynamic cycle by alternative movements of the heat transfer fluid synchronized with the magnetic field changes between areas under and outside the magnetic field, without any interference between the magnetic circuit and the heat transfer circuit.

[0042] The active elements 2 are preferably arranged side by side on the circumference of the stator 30 in order to maximize the amount of MCM material present in the volume of the air gap E. With this in mind, the space between two consecutive active elements 2 is chosen to be as narrow as possible in order to reduce to a minimum the volume of non-magneto-caloric material in the magnetic circuit arranged in the air gap E, to make the rotational motion of the magnetic device 3 as smooth and continuous as possible, to require a rotational torque as uniform as possible, and to induce a reduction in jerks and energy consumption.

[0043] The active elements 2 are furthermore regularly distributed at a distance from one another in the circumferential direction by a constant step, the number of active elements 2 being preferably a multiple of the number of magnetic poles PM of the magnetic device 3. Thus, at each instant of each thermodynamic work cycle, the active elements 2 are divided into two groups of equal number, namely a group of active elements 2 located in the area under the magnetic field facing the magnetic poles PM and a group of active elements 2 located in the area outside the magnetic field outside the magnetic poles PM. This particular arrangement in the generator 1 allows a good distribution between the areas under the magnetic field and outside the magnetic field, which makes it possible to optimize the thermodynamic cycle.

[0044] With more particular reference to Figures 7 and 8, each active element 2 is represented in the form of an independent rod and comprises a material support 32 in the longitudinal direction along X. The material support 32 is preferably made of a slightly thermally conductive and electrically insulating material, such as, by way of non-limiting examples, polymer-based synthetic materials, carbon-fiber-based composite materials, stainless steel, silica-based or resin-based natural materials. The material support 32 can possibly be thermally insulated on at least one of its upper and lower faces with respect to the magnetic rotor. Each active element 2 is configured to be housed axially directly in the stator 30 or in a support 33 included in or forming said stator 30. An example of a support 33 is shown in Figure 2 and comprises mounting rails 34 extending axially along X and regularly distributed on the circumference of the stator 30. The mounting rails 34 are each defined by a U-shaped wall, although this shape is not limiting. The support 33 is preferably made of a magnetically neutral and non-conductive material, such as, by way of non-limiting example, polymer-based synthetic materials, carbon-fiber-based composite materials, stainless steel, silica-based or resin-based natural materials. In the example shown in FIG. 2, the support 33 is formed from one single annular part. This example is not limiting, since the support 33 can be formed from several parts assembled side by side, each part extending over an annular sector and corresponding to an annular sector of a magnetic pole PM. The support 33 is not essential, since the material carriers 32 can be provided on their side walls with complementary interlocking means that allow them to be assembled to one another by a sliding connection along X.

[0045] In the illustrated example, the support 33 of the stator 30 has a length greater than that of the rotors 4, 5 in order to provide at least one fixing area ZF located outside the magnetic device 3 at at least one of the ends of said stator 30. In this way, the material carrier 32 can be easily inserted and removed from the stator 30 and can be fixed by screws or any other removable fixing members in fixing holes 36 provided for this purpose in the material carrier 32 and in the support 33. Quick clip fixing means and the like may also be suitable.

[0046] The material carrier 32 has a cross section selected from among a square, a rectangle, a trapezoid, a hollow cylindrical segment. In the illustrated example, the cross section of the material carrier 32 is trapezoidal in order to optimize the effective volume of the stator 30. The length of the material carrier 32 depends on the length of the magnetic device 3, which is determined according to the targeted power and / or temperature difference of the generator 1. The longitudinal design along X of the magnetic device 3 and of the active element 2 is advantageous since it makes it possible to facilitate and streamline the manufacture of the generator 1 for the specifications and targeted applications, in variable temperature ranges, without increasing the diameter of the generator 1, by taking advantage of the number of elementary modules 17 of the magnetic device 3 assembled in series and thus over the axial length of the generator 1 around the axis X.

[0047] The material carrier 32 of each active element 2 comprises an inner housing 35 arranged to receive at least one MCM forming a set of flow passages 31 allowing bidirectional axial circulation of a heat transfer fluid through at least one porous MCM material. In the example shown, the heat transfer fluid is a fluid. The material carrier 32 therefore comprises at least one fluid connector 37, 38 at each of its ends to connect the active element 2 to a heat transfer circuit (not shown). In the example shown, the material carrier 32 comprises two fluid connectors 37, 38 at each of its ends, corresponding respectively to a fluid inlet 37 and a fluid outlet 38. Advantageously, the fluid connectors 37, 38 are simple, non-rotating and therefore sealed connectors, since due to the fixed nature of the active element 2, they cannot generate leakage. The material carrier 32 also comprises a distributor 39 in each end region between the fluid connectors 37, 38 and the inner housing 35 to distribute the heat transfer fluid to all of the flow passages 31.

[0048] In the illustrated example, the MCM contained in each material carrier 32 is shown in the form of one or more porous MCM blocks 40 with an amorphous or textured structure. Each porous MCM block 40 may be composed of material strips, regular or not, or of any other material structure. According to the illustrated example, in each porous MCM block 40, the material structures 41 are advantageously in the form of strips, preferably axially oriented along X, parallel to the longitudinal axis B of the material carrier 32. The strips also extend radially, parallel to the magnetic field lines in the air gap E. The axial orientation of the material structures 41 along X allows for an alternative circulation of the heat transfer fluid between the cold end EF and the hot end EC of the generator 1. The radial orientation of the material structures 41 also allows for cutting eddy currents and reducing local demagnetizing fields. The terms "axial" and "radial" used are specific to the cylindrical shape of the generator 1 as illustrated, but also apply to the terms "longitudinal" and "transverse", respectively, of the generator 1 of a linear shape, not illustrated.

[0049] Furthermore, the material structures 41 in the form of strips are arranged at intervals (not visible) from one another, which intervals form a set of flow paths 31 allowing bidirectional axial circulation along X of the heat transfer fluid. The intervals between the material structures 41 form flat, narrow fluid passages of regular cross section, which make it possible to facilitate a fluid flow of the heat transfer fluid along X through the generator 1.

[0050] The porous MCM blocks 40 can be made from one and the same MCM or from different MCMs or from different MCM compositions. The porous MCM blocks 40 composed of different MCMs may or may not be separated from each other by a joining block 42. Furthermore, the different MCMs or MCM compositions are preferably stored or sequenced according to a stepwise or continuous progression of the Curie temperature (Tc) increase from a cold source located at the cold end EF to a hot source located at the hot end EC, to allow matching the Curie temperature (Tc) to the temperature gradient (difference) formed in the MCM volume of the generator 1.

[0051] In a variant not shown, the MCM contained in each material carrier 32 may also be in the form of one or more porous MCM blocks, obtained, for example, by sintering pores constituting fluid passages for the heat transfer fluid.

[0052] The material carrier 32 further comprises a cover 43 for sealingly closing the inner housing 35. The mounting rails 34 provided on the material carrier 32 and on the support 33 can be provided with guide means for axial translation (not shown) in their corresponding walls, such as grooves, ridges, etc. The material carriers 32 can also be provided with assembly means and / or guide means for axial translation (not shown) together in their corresponding walls, if they are mounted without the support 33.

[0053] The longitudinal shape of the active element 2 along X is particularly advantageous since it makes it possible to have, if necessary, fluid connectors 37, 38 or any other thermal or mechanical connection with the cold and hot sources at one or both axial ends of the stator 30. In this way, the fluid connectors 37, 38 are located close to a distributor 44 (FIG. 9) provided at one or both axial ends of the generator 1, which makes it possible to minimize the length of the pipes of the heat transfer circuit and the radial size of the generator 1.

[0054] In the case of a heat transfer fluid, by way of example and not of limitation, the distributor 44 is controlled by an actuator selected from among mechanical, hydraulic, electric and / or electronic actuators, in synchronization with the areas under and outside the magnetic field, according to a switching frequency determined according to the frequency of the thermodynamic work cycle. The distributor 44 can be controlled directly, for example, by the rotation of the magnetic device 3 by a cam 45 fixed to the internal magnetic rotor 5 or to the external magnetic rotor 4, which allows the distributor 44 to be actuated by a section 46, as shown in FIG. 9. Any other equivalent means for controlling the distributor 44 can also be suitable.

[0055] The longitudinal design of the active elements 2 along X results in several advantages: easier manufacturing of the active elements 2 in the form of independent rods, simplified installation and removal of the active elements 2 in the stator 30, standardization of parts such as the porous MCM block 40, reduced cost, simplified heat transfer circuits, and reduced load losses due to shorter pipes.

[0056] In general, the longitudinal design along X of the magnetic device 3 and of the active element 2 further makes it possible to easily increase the power output and / or working temperature difference of the generator 1 by increasing the length of the magnetic device 3 and the length of the active element 2, and thus the total length of the generator 1, without increasing its radial dimensions, which is advantageous in terms of compactness and size of the generator 1.

[0057] Although the generator 1 according to the invention is represented in a cylindrical shape with a rotating magnetic device 3, this example is not limiting. A linear shape can absolutely be envisaged in which the stator 30 and the rotors 4, 5 are flattened and the rotors 4, 5 are moved linearly with an alternative translational motion relative to the stator 30. Naturally, a cylindrical shape allows the rotors 4, 5 to be moved in a continuous rotational motion, which is much more energetically efficient, simpler and cheaper to realise.

[0058] The present invention is of course not limited to the described embodiment examples, but extends to any modifications and variations obvious to a person skilled in the art within the scope of the appended claims. Moreover, the technical features of the different embodiments and variations described above can be combined with each other in whole or in part. [Explanation of symbols]

[0059] 1 magneto-calorific generator, 2 active element, 3 magnetic device, magnetic assembly, 4 outer magnetic rotor, 5 inner magnetic rotor, 6 magnetic generator, magnet, 7 magnetic generator, magnet, 8 magnetic field homogenizing device, 9 electric machine, 10 toothed belt, 11 peripheral toothed ring, 12 toothed pulley, 13 bearing, 14 peripheral guide member, 15 guide ring, 16 flange, 17 basic module, 18 magnetic shell, 19 basic magnetic sheet, 20 orifice, 21 lug, 22 end magnetic sheet, 23 ridge, 24 groove, 25 orifice, 26 lug, 30 stator, 31 flow passage, 32 material carrier, 33 support, 34 mounting rail, 35 inner housing, 36 fixing hole, 37 fluid connector, fluid inlet, 38 fluid connector, fluid outlet, 39 distributor, 40 Porous MCM block, 41 material structure, 42 joining block, 43 cover, 44 distributor, 45 cam, 46 section, A rotating shaft, B longitudinal shaft, C casing, E air gap, EC hot end, EF cold end, PM magnetic pole, ZF fixed area

Claims

1. A magnetocaloric generator (1) comprising a set of active elements (2) based on magnetocaloric materials (MCM) and a magnetic device (3) arranged movably with respect to the set of active elements (2), said magnetic device (3) comprises two superimposed magnetic rotors, i.e. an outer magnetic rotor (4) and an inner magnetic rotor (5), defining an air gap (E) between said outer magnetic rotor and said inner magnetic rotor; The external magnetic rotor (4) and the internal magnetic rotor (5) have one and the same number of magnetic poles (PM), A set of the active elements (2) constitute a stator (30) disposed in the air gap (E), the active element (2) extends longitudinally within the stator (30) between a hot end (EC) and a cold end (EF) of the magneto-calorific generator; 1. A magnetic calorific generator, characterized in that one of said external and internal magnetic rotors (4, 5) is coupled, on the one hand, to an electric machine (9) by a mechanical coupling and, on the other hand, to the other of said internal and external magnetic rotors (4, 5) by a magnetic coupling, whereby said internal and external magnetic rotors move in one and the same direction and are magnetically synchronized.

2. the magnetocaloric generator has a cylindrical shape; said outer and inner magnetic rotors (4, 5) being concentric about their axis of rotation (A); 2. A magnetic calorific generator according to claim 1, characterized in that said stator (30) has an annular shape concentric with said outer and inner magnetic rotors (4, 5).

3. The external magnetic rotor (4) is coupled to the electric machine (9), said outer magnetic rotor (4) comprising a peripheral toothed ring (11); 3. A magnetic calorific generator according to claim 2, characterized in that the mechanical coupling between the external magnetic rotor (4) and the electric machine (9) comprises a power transmission by means of a toothed belt (10) meshing with the peripheral toothed ring (11).

4. said magnetocaloric generator comprises at least means for rotatably guiding said external magnetic rotor (4) and said internal magnetic rotor (5) carried by a casing (C), 4. A magnetic calorific generator according to claim 2 or 3, characterized in that the means for rotatably guiding the external magnetic rotor (4) comprise peripheral guiding elements (14) attached to the ends of the external magnetic rotor (4) and arranged to circulate on guiding paths belonging to the casing (C).

5. 5. A magnetic calorific generator according to claim 4, characterized in that said peripheral guide members (14) are mounted on said outer magnetic rotor (4) in peripheral sectors located outside said magnetic poles (PM).

6. the guide path is provided on a guide ring (15) attached to the casing (C); 5. A magnetocaloric generator according to claim 4, characterized in that the guide ring (15) is of a material whose hardness is greater than the hardness of the material of the casing (C).

7. said magnetic device (3) being of modular construction and comprising an assembly of at least two superimposed elementary modules (17); Each of the basic modules (17) comprises a portion of the external magnetic rotor (4) and a portion of the internal magnetic rotor (5); 7. A magnetic calorific generator according to any one of claims 1 to 6, characterized in that the number of basic modules (17) defines the length of the magnetic device (3) and is determined depending on the targeted power and / or temperature difference of the magnetic calorific generator (1).

8. 8. A magnetic calorific generator according to claim 7, characterized in that the basic modules (17) comprise complementary interlocking geometries arranged on the one hand to centre the basic modules (17) with respect to the axis of rotation (A) and to index the angular position of the basic modules (17) with respect to one another.

9. 2. A magnetic heat generator according to claim 1, characterized in that the magnetic arrangement (3) comprises a field homogenising device (8) facing the air gap (E) and superimposed on the magnetic poles (PM) of the external magnetic rotor (4) and / or the internal magnetic rotor (5).

10. said active elements (2) being porous and each of said active elements being passed by a heat transfer circuit enabling the alternative circulation of a heat transfer fluid from said hot end (EC) to said cold end (EF) during a first working cycle of said magnetic calorific generator and conversely from said cold end (EF) to said hot end (EC) during a second working cycle, 10. A magnetic heat generator according to any one of claims 1 to 9, characterized in that the direction of circulation of the heat transfer fluid is perpendicular to the direction of the magnetic field lines generated by the magnetic poles (PM) of the magnetic device (3).

11. the number of active elements (2) of the assembly is a multiple of the number of magnetic poles (PM) of said magnetic device (3); 11. A magnetic heat generator according to claim 10, characterized in that the active elements (2) are arranged side by side on the circumference of the stator (30).

12. Each of the active elements (2) comprises a longitudinal material carrier (32) housed in the stator (30), The material support (32) has a cross section selected from the group consisting of a square, a rectangle, a trapezoid, and a hollow cylinder; 12. A magnetocaloric generator according to claim 10 or 11, characterized in that the length of the material carrier (32) is determined depending on the length of the magnetic device (3) and on the targeted power, effectiveness and / or temperature difference of the magnetocaloric generator.

13. 13. A magnetic calorific generator according to claim 12, characterized in that the material carrier (32) of each of the active elements (2) comprises an inner housing (35) configured to receive at least one MCM and at least one fluid connector (37, 38) at each end of the material carrier (32), configured to connect the active element (2) to the heat transfer circuit.

14. 14. A magnetic calorific generator according to claim 13, characterized in that the material carrier (32) further comprises at least one distributor (39) in each end region between the fluid connectors (37, 38) and the inner housing (35).

15. said active element (2) comprises at least one porous MCM block (40) in the form of regular material strips or material structures (41) oriented parallel to the longitudinal axis (B) of the material carrier (32) and spaced apart from one another; 15. A magnetic heat generator according to any one of claims 10 to 14, characterized in that the spacing forms a set of longitudinal flow paths (31) allowing bidirectional circulation of the heat transfer fluid through each active element (2).

16. said active element (2) comprises several porous MCM blocks (40) each made of one and the same MCM or different MCMs or different MCM compositions; 16. A magnetic calorific generator according to claim 15, characterized in that the different MCMs or MCM compositions are stored according to increasing or decreasing Curie temperatures (Tc) in a stepwise or continuous progression.

Images