EP3224551A1

EP3224551A1 - Magnetocaloric thermal apparatus

Info

Publication number: EP3224551A1
Application number: EP15808123.2A
Authority: EP
Inventors: Christian Muller
Original assignee: Cooltech Applications SAS
Current assignee: Cooltech Applications SAS
Priority date: 2014-11-26
Filing date: 2015-11-25
Publication date: 2017-10-04
Also published as: JP2017537291A; US10365019B2; KR20170088863A; BR112017010024A2; CN107003041B; CN107003041A; US20170336108A1; WO2016083440A1; FR3028927A1

Abstract

The invention relates to a magnetocaloric thermal apparatus (1) with a structure that is rotary about a longitudinal axis (L), comprising a magnetic arrangement defining at least two mutually parallel air gaps (E₁, E₂) and configured to create within each of said air gaps (E₁, E₂) a magnetic field that can vary about the longitudinal axis (L). Two supports (S₁, S₂) bear magnetocaloric elements (2) and are each positioned in the midplane (P₁, P₂) of one of said air gaps (E₁, E₂). The magnetic arrangement and the supports (S₁, S₂) are in relative movement with respect to one another about the longitudinal axis (L) and positioned angularly with respect to one another about the longitudinal axis (L) in such a way as to generate a phase shift between the magnetic cycle experienced by the magnetocaloric elements (2) of one of the supports (S₁) in one of the air gaps (E₁,E₂), and that experienced by the magnetocaloric elements of the other support (S₂) in the other air gap (E₁, E₂).

Description

MAGNETOCALORIC THERMAL APPARATUS

Technical Field: The present invention relates to a magnetocaloric thermal apparatus with a rotating structure about a longitudinal axis, said thermal apparatus comprising a magnetic arrangement defining at least two gaps at least partially superimposed and parallel to each other, and arranged to create in each of said air gaps a variable magnetic field around the longitudinal axis, at least two supports at least partially superimposed, each placed in the median plane of one of said air gaps and carrying magnetocaloric elements at least partially superimposed between said supports, said magnetic arrangement and said supports being relative displacement relative to each other about the longitudinal axis to subject the magnetocaloric elements of each support a magnetic cycle created by the variable magnetic field in the corresponding gap.

Prior art

The present invention relates to the field of magnetic refrigeration, and more particularly that of thermal devices using the magnetocaloric effect of so-called magnetocaloric materials.

The magnetocaloric effect (EMC) of magnetocaloric materials consists of a variation of their temperature when they are subjected to a variable magnetic field in intensity. It suffices to subject these materials to a succession of cycles comprising an alternation of magnetization and demagnetization phases and to perform a heat exchange with a heat transfer fluid passing through said materials from one end to the other to achieve the widest possible temperature variation. between the ends of said materials. This cycle is repeated up to frequencies of several Hertz. The efficiency of such a magnetic refrigeration cycle is about 50% greater than that of a typical refrigeration cycle. The magnetocaloric material heats up almost instantaneously when it is placed in a magnetic field and it cools in the same thermal dynamics when it is removed from the magnetic field. During these magnetic phases, the heat transfer fluid will either be heated in contact with the magnetocaloric material during a so-called magnetization phase, or be cooled in contact with the magnetocaloric material during a so-called demagnetization phase. Generally speaking, in applications operating at ambient temperature, the coolant is a liquid and circulates in existing straight channels or pores in the magnetocaloric material. For this purpose, the coolant can be pure water or added antifreeze, a glycol product or a brine, for example.

The higher the magnetic field in the air gap, the greater the magnetocaloric effect induced in the magnetocaloric material, which has the effect of increasing the thermal power as well as its temperature gradient between its two input ends. heat transfer fluid outlet, and therefore the overall efficiency of such a magnetocaloric thermal device. In the same way, as the frequency of the cycles increases, the thermal power (for example: cooling) delivered by the thermal apparatus also increases. For this power to increase in proportion to the increase of the frequency, it is necessary to have a magnetic arrangement capable of generating a uniform and intense magnetic field in at least one gap and to be able to achieve the relative displacement of this magnetic arrangement. compared to the magnetocaloric elements by consuming the least possible energy.

For this purpose, the rotary structures are preferred because they make it possible, on the one hand, to produce a compact thermal apparatus with the magnetic arrangement in displacement relative to the magnetocaloric material (s) and, on the other hand, to on the other hand, to present a good ratio of magnetocaloric material per volume used. Since the thermal power of the thermal apparatus depends in particular on the amount of magnetocaloric material used, such an arrangement is indeed very advantageous. The applicant has filed for this purpose the patent applications FR 2 987 433 and FR 2 994 018 for the purpose of rotating magnetic arrangements. The publication FR 2 994 018 corresponds to the preamble of claim 1. However, since the magnetic permeability of the air is lower than that of the magnetocaloric materials, the relative displacement of the magnetocaloric materials with respect to the magnetic arrangement or conversely causes in the gap an alternation of different magnetic permeabilities, with a greater magnetic attraction to the passage of the magnetocaloric material. As a result, the displacement or the angular velocity of the magnetic arrangement or the magnetocaloric elements is not naturally continuous, nor uniform and generates jolts. This situation is troublesome because it disrupts the magnetic cycle by reducing the thermal power and increasing the energy consumption. It also increases the noise level of the device and has a negative impact on its endurance and mechanical stability.

Presentation of the invention

The present invention aims to solve these drawbacks by proposing a magnetocaloric thermal apparatus comprising a particular arrangement of the magnetic arrangement and / or magnetocaloric elements making it possible to reduce the magnetic moment and thus also the mechanical moment necessary for driving the magnet. magnetic arrangement to obtain a rotational and continuous relative displacement of the magnetic arrangement with respect to the magnetocaloric materials.

For this purpose, the invention relates to a thermal apparatus as described in the preamble, characterized in that the magnetic arrangement and the supports are positioned angularly relative to each other about the longitudinal axis so as to generate a phase shift between the magnetic cycle undergone by the magnetocaloric elements of one of the supports in one of the air gaps and the magnetic cycle undergone by the magnetocaloric elements of the other support in the other gap, of so that the magnetocaloric elements penetrate progressively into the magnetic field of said gaps and this, continuously between the supports, the magnetic attraction force obtained then being almost constant. This phase shift is achieved by construction, that is to say by the particular arrangement or positioning of the magnetic arrangement and / or magnetocaloric elements between them.

In a first embodiment, the magnetic arrangement may comprise first, second and third magnetizing structures each provided with at least one pair of magnetic poles, and positioned successively along the longitudinal axis of the thermal apparatus. to define, with their pairs of magnetic poles, said air gaps, and said magnetizing structures can be positioned angularly with respect to each other about the longitudinal axis so as to generate a magnetic cycle in one of the gaps which is offset a phase shift angle with respect to the magnetic cycle in the other gap.

In this mode, the first and the third magnetizing structures may be identical, mounted with an angular offset between them corresponding to the phase shift angle. In addition, the second magnetising structure may comprise, on the one hand, first magnetic poles, which form a first air gap with the corresponding magnetic poles of the first magnetizing structure and, secondly, second magnetic poles, which form a second air gap with the corresponding magnetic poles of the third magnetizing structure, and the first and second magnetic poles of said second magnetizing structure can be mounted with an angular offset corresponding to the phase angle.

In a first variant embodiment of this first mode, the first and third magnetizing structures can be mounted head to tail and angularly offset by an angle corresponding to the phase shift angle, the first magnetic poles of the second magnetizing structure can have the same the meaning of magnetization that the magnetic poles of the first magnetising structure with which they cooperate to form the gap, the second magnetic poles of the second magnetizing structure can have the same sense of magnetization as the magnetic poles of the third magnetising structure with which they cooperate to form the gap, and the magnetization direction of the first and second magnetic poles may be the same to create a single magnetic flux circulation loop within said apparatus traversing said first, second and third magnetizing structures. In a second variant embodiment of this first embodiment, the first and third magnetizing structures may be mounted facing and angularly offset by an angle corresponding to the phase shift angle, the first magnetic poles of the second magnetising structure may have the same direction of magnetization as the magnetic poles of the first magnetizing structure with which they cooperate to form the gap and create a first circulation loop of the magnetic flux inside said apparatus passing through said first magnetic poles of the second magnetizing structure and said magnetic poles of the first magnetising structure. The second magnetic poles of the second magnetizing structure can have the same direction of magnetization as the magnetic poles of the third magnetizing structure with which they cooperate to form the gap and create a second circulation loop of the magnetic flux inside said apparatus passing through said second magnetic poles of the second magnetizing structure and said magnetic poles of the third magnetizing structure. The magnetization direction of the second magnetic poles may be opposite to that of the first magnetic poles so that the magnetic flux flows in the first loop in the opposite direction to the magnetic flux flowing in the second loop.

In addition, the magnetocaloric elements may be positioned angularly relative to each other on their supports at a predefined angle and the phase shift angle may be less than the angle between two magnetocaloric elements. adjacent.

In addition, the supports can be geometrically identical and arranged parallel to each other in the corresponding air gaps, without angular offset. Preferably, the supports are planar.

In the second embodiment of the invention, the supports may also be geometrically identical, arranged parallel to each other in the corresponding air gaps, but angularly offset relative to each other by an angle corresponding to the angle of phase shift.

In this mode, the magnetocaloric elements can be positioned angularly relative to each other on their supports at a predefined angle and the angular offset between the two supports may be less than the angle between two adjacent magnetocaloric elements.

For example, the offset angle between the two supports may be equal to half the angle between two adjacent magnetocaloric elements. In this second embodiment, the magnetic arrangement may comprise a first, a second and a third magnetizing structure positioned successively along the longitudinal axis and defining, with their magnetic poles aligned and mounted in two opposite directions of magnetization, the first and second gaps.

In both embodiments, the magnetocaloric elements may comprise N rectangular parallelepipeds provided with magnetocaloric material and arranged in a ring-shaped zone of said support, said ring being centered on the longitudinal axis. This crown can be defined by two concentric circles, called inner circle and outer circle. In this case, two of the opposite faces of the rectangular parallelepipeds forming said magnetocaloric elements said extremal faces may each be tangent to one of said concentric circles, and the longitudinal median axes of two adjacent magnetocaloric elements may form between them an angle equal to 360 / N degrees. In both embodiments, the magnetic poles may have the shape of ring portions extending over angular sectors whose angle is determined so that the input of the magnetocaloric elements in the magnetic field of said magnetic poles begins with stops belonging to one of said extremal faces. This creates a variation of magnetic induction the most progressive and continuous possible in each magnetocaloric element, which further reduces the force required to enter and leave the magnetocaloric elements in and out of the magnetic field of the air gap.

In both embodiments, the magnetocaloric elements may be positioned radially on said support.

In both embodiments, to simplify the structure of the thermal apparatus, the magnetic poles of each magnetizing structure may be identical, but mounted in two opposite directions of magnetization.

By magnetocaloric element, it is understood in the sense of the present invention a physical element comprising magnetocaloric material. A magnetocaloric element may in particular comprise several types of magnetocaloric materials and react at different temperatures, which generates a thermal gradient along the magnetocaloric element. Thus, the magnetocaloric materials constituting the magnetocaloric elements may have different Curie temperatures, ordered in ascending or descending order. The magnetocaloric elements that can be positioned in the air gap of the thermal apparatus according to the invention are intended to be in thermal contact with a coolant. This heat transfer fluid can for example flow from their cold end to their hot end during a magnetization phase of the magnetic cycle which corresponds to a phase in which the magnetocaloric elements are positioned in a gap and subjected to a magnetic field (causing an increase in their temperature) and their hot end to their cold end during a subsequent phase of demagnetization of the magnetic cycle in which the magnetocaloric elements are positioned outside the air gap and subjected to a zero magnetic field (causing a decrease in their temperature). A magnetocaloric cycle thus comprises a magnetization phase and a demagnetization phase. The thermal contact between the heat transfer fluid and the magnetocaloric elements can be achieved by a heat transfer fluid passing along or through the magnetocaloric elements. The magnetocaloric elements may comprise fluid circulation passages extending between the two ends of the magnetocaloric elements. These passages can be made thanks to the porosity of the magnetocaloric materials, or channels for example obtained by a set of magnetocaloric material plates possibly grooved or preformed, assembled and spaced uniformly or made in blocks of machined magnetocaloric material. The magnetocaloric elements may also be in the form of calibrated sized spheres so that the interstices form fluid passages. Any other embodiment allowing the coolant to heat exchange with the material constituting a magnetocaloric element can, of course, be suitable.

Preferably, the permanent magnets described above and used to make the magnetic field generator according to the present invention exhibit a uniform induction.

Brief description of the drawings: The present invention and its advantages will become more apparent in the following description of embodiments given by way of non-limiting example, with reference to the appended drawings, in which:

FIG. 1 is a simplified schematic representation of a magnetocaloric thermal apparatus according to a first embodiment of the invention; FIG. 2 is a schematic view of the apparatus of FIG. 1, illustrating more particularly its magnetic arrangement;

FIG. 3 is a view similar to that of FIG. 2 of an apparatus according to an alternative embodiment of the first embodiment of the invention,

FIG. 4A is a simplified schematic representation of a magnetocaloric thermal apparatus according to a second embodiment,

FIG. 4B is a representation of the two superimposed magnetocaloric element supports, illustrating their angular displacement around the longitudinal central axis,

FIG. 5 is a schematic view of the apparatus of FIG. 4A, illustrating more particularly its magnetic arrangement, and

Figure 6 is similar to that of Figure 5 of an apparatus according to an alternative embodiment of the second embodiment of the invention. Illustrations of the invention and different ways of making it:

In the exemplary embodiments illustrated, the identical parts or parts bear the same numerical references. Figures 1 to 6 show schematically a thermal apparatus 1, 10, 100, 110 magnetocaloric structure rotatable about a longitudinal axis L and two embodiments of the invention. This thermal apparatus 1, 10, 100, 110 essentially comprises a magnetic arrangement comprising three magnetizing structures SM ₁ , SM ₂ , SM ₃ at least partially superimposed and parallel to one another, along said longitudinal axis L, which will be described below, two supports Si, S ₂ preferably identical, at least partially superimposed and parallel to each other, arranged in the air gaps E ₁ , E ₂ defined by the magnetizing structures and carrying magnetocaloric elements 2, a device (not shown) for circulating a heat transfer fluid through the magnetocaloric elements 2, and heat exchangers (not shown) for effecting heat exchange with the environment or an external application.

Preferably, the first magnetizing structure SMi and the third magnetizing structure SM ₃ of the thermal apparatus 1, 10, 100, 110 are identical. This makes it possible to have a single piece likely to constitute the first SMi and the third SM ₃ magnetizing structures. In the embodiments shown in FIGS. 1 and 2, and 4A, 4B and 5, these first and third magnetizing structures SM ₁ , SM ₃ are mounted head to tail and arranged facing each other parallel to a plane transverse central P, with an angular offset a between them for the first embodiment (FIGS. 1 and 2) and without angular displacement for the second embodiment (FIGS. 4A, 4B and 5). In the variants shown in FIGS. 3 and 6, the first and third magnetizing structures SM ₁ , SM ₃ are simply mounted facing each other parallel to the central transverse plane P, with an angular offset a between them for the variant of FIG. 3 and without angular offset for the variant of FIG. 6.

In both embodiments, the second magnetizing structure SM ₂ is interposed between the first magnetizing structure SMi and the third magnetizing structure SM ₃ so as to delimit at least two and in the example shown four gaps Ei, E ₂ at least part superposed two by two, and diametrically opposed in pairs, around transverse planes Pi and P ₂ parallel to the central plane P and in which are mounted each time a support S1, S2 carrying the magnetocaloric elements 2. In addition, the air gaps Ei and E ₂ can have the same volume. In the two illustrated embodiments, the magnetocaloric elements 2 of each support S1, S2 are divided into four groups, of which two groups diametrically opposed each located in one of the air gaps E ₁ , E ₂ and subjected to a magnetization phase during which they generate calories, alternated with two other groups each located outside said gaps E ₁ , E ₂ and subjected to a degaussing phase during which they generate frigories. This arrangement is of course dependent on the number of magnetic poles defined by the magnetizing structures SMi, SM ₂ , SM ₃ .

In all cases, the magnetocaloric elements 2 of the supports S1, S2 are at least partially superimposed or substantially aligned longitudinally with each other, and are in the same magnetic state at the phase shift angle. Thus, they can be connected together in the same thermal loop to simplify and optimize the design of devices for circulating coolant (not shown). The superposition along the longitudinal axis L of magnetizing structures SMi, SM ₂ , SM ₃ and supports SI, S2 makes it possible to increase the quantity of magnetocaloric elements 2 which are in the same magnetic state in order to increase the gradient if they are connected in series, or the thermal power if they are connected in parallel, without having to multiply the number of devices (not shown) for circulating the coolant through said magnetocaloric elements 2. a first embodiment with reference to Figures 1 to 3, the first and third magnetizing structures SMi, SM ₃ are mounted relative to each other with an angular offset of an angle a. Thus, in the air gaps E1 and E2 at least partially superimposed magnetic induction profiles which are identical but phase-shifted angularly relative to each other of the angle a. This makes it possible to compensate for the magnetic force induced by the penetration of the supports Si and S ₂ into their air gaps E ₁ , E ₂ respectively. This angular offset a makes it possible to smooth the magnetic force penetration into the magnetic field of the magnetocaloric elements 2. By this angular offset, the magnetocaloric elements 2 penetrate progressively into the magnetic field of said air gaps E ₁ , E ₂ and continuously between the supports Si and S ₂ . As a result, there is a continuous flow of magnetocaloric material entering or leaving the field magnetic force and the magnetic attraction force is then almost constant and causes practically no jerk in the movement of magnetic structures.

In both embodiments, each magnetizing structure SMi, SM ₂ , SM3 comprises a base 6, 7, 8 in a ferromagnetic material on which permanent magnets and / or ferromagnetic parts constituting at least one pair of magnetic poles are mounted. , P ₁₂ ; P ₂₁ , P ₂₂ ; P ₂₃ , P ₂₄ ; P31, P ₃₂ diametrically opposed. In the examples illustrated, the magnetic poles each comprise three magnets mounted on the base 6, 7, 8. The base of the first and third magnetizing structures SM ₁ , SM ₃ is made of a material capable of conducting the magnetic field which must circulating between the two magnetic poles Pu, P ₁₂ ; P ₃ i, P ₃₂ of each first and third magnetizing structures SMi, SM ₃ .

To do this, the magnetic pole Pu of the first magnetizing structure SMi has a magnetic induction resultant Ru which is, on the one hand, parallel to the longitudinal axis L and to the resultant magnetic induction Ri ₂ of the another magnetic pole P ₁₂ of this first magnetizing structure SMi and, on the other hand, of opposite direction to the magnetic induction resultant Ri _{2 of} said magnetic pole P ₁₂ . This applies to other magnetizing structures SM ₂ and SM ₃ . Thus, for each pair of magnetic poles P ₂₁ , P ₂₂ ; P ₂₃ , P ₂₄ ; P ₃ i, P ₃₂ of the same magnetizing structure and located in the same pair of gaps Ei, E ₂ , the induction resultants R ₂ i, R ₂₂ ; R ₂₃ , R ₂₄ ; R31, R ₃₂ are parallel to each other and to the longitudinal axis L and in the opposite direction. Therefore, with reference to the first embodiment, by orienting the magnetization directions or magnetic induction resultants Ru, R ₂ i, R ₂₃ , R ₃ i magnetic poles Pu, P ₂₁ , P ₂₃ , P ₃ i located on the same side of the thermal apparatus 1 in one direction and that Ri ₂ , R ₂₂ , R ₂₄ , R ₃₂ of the opposite magnetic poles P ₁₂ , P ₂₂ , P ₂₄ , P ₃₂ located on the other side of the 1 in the opposite direction, as is more particularly apparent in Figure 2, the magnetic induction flux induced by the magnetic arrangement forms a single closed loop B in the apparatus 1. In FIG. reference to FIG. 2, the magnetic flux flows in the thermal apparatus 1:

from the magnetic pole Pu of the first magnetizing structure SMi to the first magnetic pole P ₂₁ of the second magnetizing structure SM ₂ , crossing one of the air gaps E 1 and the support Si, then

via the base 7 of ferromagnetic material of the second magnetizing structure SM ₂ , from the first magnetic pole P ₂₁ to the second magnetic pole P ₂₃ , and then

from the second magnetic pole P ₂₃ to the magnetic pole P ₃ i of the third magnetizing structure SM ₃ , crossing one of the gaps E ₂ and the support S ₂ , then

via the ferromagnetic base 8 of the third magnetizing structure SM ₃ , the magnetic pole P ₃ i to the magnetic pole P ₃₂ , and then

from the magnetic pole P ₃₂ of the third magnetizing structure SM ₃ to the second magnetic pole P ₂₄ of the second magnetizing structure SM ₂ while passing through the other air gap E ₂ and the support S ₂ , then

from the second magnetic pole P ₂₄ of the second magnetizing structure SM ₂ to the first magnetic pole P ₂₂ of the second magnetizing structure SM ₂ via the base 7 made of ferromagnetic material, then

from the first magnetic pole P ₂₂ of the second magnetizing structure SM ₂ to the magnetic pole P ₁₂ of the first magnetizing structure SMi while passing through the other air gap Ei and the support Si, then

via the ferromagnetic base 6 of the first magnetizing structure SMi, from the magnetic pole P ₁₂ to the magnetic pole Pu.

With reference to the variant of this embodiment illustrated in FIG. 3, in which the thermal generator 10 stands out solely by a different orientation of the magnetization directions or the resultants of magnetic induction of certain magnetic poles, we obtain two magnetic loops Bi and B ₂ . In this variant, the magnetic induction results R ₂₃ and R ₂₄ of the second magnetic poles P ₂₃ and P ₂₄ of the second magnetizing structure SM ₂ are oriented in the opposite direction to the magnetic induction results R21 and R22 of the first magnetic poles P21 and P22 of the second magnetizing structure SM2. The resulting magnetic induction Ru and R12 magnetic pole Pu and P ₁₂ of the first magnetizing SMi structure are oriented in the same direction as the magnetic induction resulting R21 and R22 of the first magnetic poles _P21 and P22 of the second structure magnetising SM2 with which they cooperate to form the first pair of air gaps Ei. This gives the first magnetic loop Bi. In the same manner, the magnetic induction results R31 and R32 of the magnetic poles P31 and P32 of the third magnetizing structure SM3 are oriented in the same direction as the magnetic induction results R23 and R24 of the second magnetic poles P23 and P24 of the second magnetizing structure SM2 with which they cooperate to form the second pair of air gaps E2. This gives the second magnetic loop B2. With reference to FIG. 3, the magnetic flux flows in the thermal apparatus 10, in the first loop Bi:

the magnetic pole Pu of the first magnetizing structure SMi at the first magnetic pole P ₂₁ of the second magnetizing structure SM2, crossing one of the air gaps Ei and the support Si, then

via the ferromagnetic base 7 of the second magnetizing structure SM2, from the first magnetic pole P ₂₁ to the first magnetic pole P22, and then

from the first magnetic pole P22 to the magnetic pole P ₁₂ of the first magnetizing structure SMi, while passing through the other air gap Ei and the support Si, and then via the base 6 made of ferromagnetic material of the first magnetizing structure SMi, from the pole magnetic P ₁₂ at the magnetic pole Pu.

In the same way, with reference to FIG. 3, the magnetic flux flows in the thermal apparatus 10, simultaneously in the second loop B2:

of the third structure P31 magnetic pole magnetizing SM3 P23 to the second magnetic pole of the second structure magnetizing SM2, passing through one of the gaps E2 and S ₂ substrate, then via the ferromagnetic base 7 of the second magnetizing structure SM ₂ , the second magnetic pole P ₂₃ to the second magnetic pole P ₂₄ , and then

from the second magnetic pole P ₂₄ to the magnetic pole P ₃₂ of the third magnetizing structure SM ₃ , crossing the other air gap E ₂ and the support S ₂ , then via the base 8 made of ferromagnetic material of the third magnetizing structure SM ₃ , from the magnetic pole P ₃₂ to the magnetic pole P ₃ i.

In both embodiments, the supports Si, S ₂ and the magnetizing structures SM ₁ , SM ₂ , SM ₃ are mounted around the longitudinal axis L of the thermal apparatus 1 in a relative rotational movement with respect to each other. so that the magnetocaloric elements 2 can enter and exit alternately gaps Ei, E ₂ .

Preferably, in order to simplify the mechanical construction and the fluid flows, the supports Si and S ₂ are fixed and the magnetizing structures SMi, SM ₂ , SM ₃ are rotated with respect to the longitudinal axis L by any means of adapted training. For this purpose, the relative position of the magnetizing structures SMi, SM ₂ , SM ₃ between them is kept fixed, either rigidly or by magnetic attraction between them, for example. In the latter case, at least one of the magnetizing structures SMi is rigidly mounted on the longitudinal axis L which drives it in a rotational movement and the other magnetizing structures SM ₂ , SM ₃ are mounted free to rotate on the longitudinal axis L and driven in rotation by the magnetic attraction of the magnetizing structure SMi which moves.

Although the magnetocaloric elements 2 shown in the accompanying drawings have the shape of rectangular parallelepipeds, this configuration is not limiting, and other forms may be conceivable. Thus, by way of example, the magnetocaloric elements can be in the form of blocks, porous or having circulation channels, whose base is trapezoidal or has side faces which are not parallel to each other.

The supports Si, S ₂ comprising the magnetocaloric elements 2 are preferably identical geometrically.

The present invention differs from those disclosed in the aforementioned applications by the particular positioning of the magnetizing structures SMi, SM ₂ , SM ₃ between them and / or by the positioning of the supports Si and S ₂ between them. Indeed, an angular offset is achieved, which provides a magnetic induction preferably identical, but shifted or out of phase between the gaps Ei, E ₂ at least partially superimposed. In this way, a magnetic compensation appears between the magnetic forces necessary to achieve a continuous displacement of the magnetizing structures SMi, SM ₂ , SM ₃ with respect to the supports Si, S _{2 of} said magnetocaloric elements 2, or vice versa.

Thus, with reference to FIGS. 1 to 3, which represent a magnetocaloric thermal device 1, according to a first embodiment of the invention, the first and third magnetizing structures SM ₁ , SM ₃ are angularly offset with respect to one another. other from an angle a. FIGS. 4A, 4B, 5 and 6 represent, for their part, a thermal apparatus 100, 110 made according to a second mode, in which the Siet S ₂ supports are angularly offset from each other by an angle β.

This offset angle has magnetizing structures SMi and SM ₃ in Figures 1 to 3 corresponds in this example to half the angle Θ between two consecutive magnetocaloric elements 2, the latter being arranged radially around the longitudinal axis L. The magnetocaloric elements 2 can also be orientated or arranged non-radially on their support Si, S ₂ . Such a configuration is not represented.

Preferably, the magnetocaloric elements 2 are arranged in a zone ring-shaped ring C of supports Si and S ₂ . This ring C is delimited by an inner circle 3 and an outer circle 4 which is concentric with the inner circle 3. In the examples shown, the two opposite faces farthest from said magnetocaloric elements 2 are each tangent to one of the concentric circles 3 and 4 and the longitudinal median axes of two adjacent magnetocaloric elements 2 form between them an angle Θ equal to 360 / N degrees, N being the number of magnetocaloric elements 2 carried by a support Si, S ₂ . In addition, the offset angle α magnetizing structures SM ₁ and SM ₃ is preferably smaller than the angle Θ between two adjacent magnetocaloric elements 2.

In addition, to further assist in the continuous rotation of the various moving elements in the thermal apparatus 1, 10 according to the invention, it can be provided to orient the different magnetocaloric elements 2 with respect to the lateral faces of the magnetic poles of such so that the input of the magnetocaloric elements 2 into the magnetic fields of the air gaps E ₁ , E ₂ is progressively achieved by a wedge or an angular end of the magnetocaloric elements 2, and in particular by an edge 5 belonging to one of the extreme faces F farther away from the magnetocaloric elements 2, namely the face tangent to the inner circle 3. This makes it possible to obtain a progressive entry of the magnetocaloric elements 2 into the magnetic field, and thus to promote a continuous displacement of the magnetizing structures SM ₁ , SM ₂ , SM ₃ with respect to the supports Si and S ₂ of magnetocaloric elements 2. Such a configuration can also be to be transposed in the second embodiment in which the supports Si and S ₂ are angularly offset.

In this first embodiment, illustrated in FIGS. 1, 2 and 3, the magnetic poles P ₂₁ , P ₂₂ of the second magnetizing structure SM ₂ which cooperate with the first magnetizing structure SMi are angularly offset by an angle α which corresponds to the angle of offset a with the magnetic poles P ₂₃ , P ₂₄ of the second magnetizing structure SM ₂ which cooperate with the third magnetizing structure SM ₃ . As a result, the magnetic inductions in the air gaps Ei, E ₂ are also shifted by a phase shift angle equal to the angle a.

In such a configuration, the penetration force in the field is limited because the attraction force of the support S ₂ in the magnetic field of the air gaps E ₂ does not take place at the same time as the effort of the attraction of the support Si in the magnetic field of the gaps Ei. By successive penetrations of the magnetocaloric elements 2 of the support Si in the magnetic field of the gaps Ei and magnetocaloric elements 2 of the support S ₂ in the magnetic field of the gaps E2, the magnetic force then becomes continuous and almost constant.

In this configuration, the magnetic poles of the three magnetizing structures SMi, SM ₂ , SM ₃ extend over an identical angular sector, but angularly offset for some of said magnetic poles. FIGS. 4A, 4B, 5 and 6 show the second embodiment in which the thermal apparatus 100, 110 comprises two pairs of parallel air gaps E ₁ , E ₂ in which the supports S ₁ and S ₂ are arranged with an angular offset β between them. More precisely, the magnetocaloric elements 2 of the two supports Si and S ₂ , strictly aligned longitudinally with each other in the preceding embodiment and perfectly superimposed, are in this variant slightly offset longitudinally of said angle β and partially superimposed to generate a continuity of magnetocaloric material. between the two supports Si and S ₂ . FIG. 4B represents for this purpose only the positioning of the two supports Si and S ₂ relative to each other, superimposed and offset by an angle β. For ease of understanding, the magnetocaloric elements 2 of the support Si are shown with hatching, the latter being able to illustrate in particular the heat transfer fluid circulation channels through said magnetocaloric elements 2, whereas the magnetocaloric elements 2 of the support S ₂ do not include hatching. This configuration represents a particular case in which the offset angle β is equal to half the angle Θ between the two longitudinal median axes of two adjacent magnetocaloric elements 2 of a support Si, S ₂ . The cutting plan of FIGS. 5 and 6 passing through the longitudinal axis L section of the magnetocaloric elements 2 of the support Si mounted in the first gaps Ei but not the magnetocaloric elements 2 of the support S ₂ mounted in the second air gaps E ₂ . This is due to the angular offset β between the two supports Si and S ₂ . The magnetizing structures SM ₁ , SM ₂ , SM ₃ may be the same as those described in the first embodiment of FIGS. 1 to 3, with the difference that the magnetic poles Pu, P ₁₂ ; P ₂₁ , P _22; P23, P24; P31, P32 are all aligned with each other longitudinally, without angular displacement, as shown in FIGS. 4A, 4B, 5 and 6. Circulation of the magnetic flux in the thermal apparatus 100 of FIGS. 4A, 4B and 5 is identical to that described in relation to the thermal apparatus 1 of FIGS. 1 and 2, without however any angular displacement between the magnetic poles. In the same way, the circulation of the magnetic flux in the thermal apparatus 110 of FIG. 6 is identical to that described in relation with the thermal apparatus 10 of FIG. 3, without however any angular displacement between the magnetic poles. Thus, the magnetic cycles experienced by the magnetocaloric elements 2 in the air gaps E ₁ and E ₂ are offset by a phase shift angle equal to the offset angle β, which makes it possible to achieve a magnetic compensation between the forces of attraction / repulsion occurring in the air gaps E ₁ and E ₂ between the magnetocaloric elements 2 and the magnetic poles Pu, P ₁₂ ; P ₂₁ , P _22; P23, P24; P31, P32 magnetizing structures SMi, SM ₂ , SM3. This results in a smoothing of the displacement of the magnetic structures with respect to the supports Si and S ₂ . In other words, there is a continuous flow of magnetocaloric material which enters the magnetic field and the magnetic attraction force is then almost constant and causes practically no jerk in the displacement of the magnetizing structures.

In the thermal devices 1, 10, 100, 110 described, a magnetic cycle comprises two magnetization phases, corresponding, for the magnetocaloric elements 2, to a position between two magnetic poles Pu, P ₂₁ ; P ₁₂ , P ₂₂ ; P23, P31; P24, P32, and two corresponding demagnetization phases, for the magnetocaloric elements 2, at a position outside said poles. As a result, during a complete revolution of the magnetic arrangement around the longitudinal axis L, each magnetocaloric element 2 experiments two successive magnetocaloric cycles comprising two magnetizations and two demagnetizations.

In the examples of thermal devices 100, 110 shown in FIGS. 4A, 4B, 5 and 6, the offset angle β between the two supports Si and S ₂ corresponds to half the angle Θ between two magnetocaloric elements 2 adjacent. In addition, as already described above, to improve the continuous rotation of the magnetic arrangement, the magnetic poles Pu, P ₁₂ , P ₂₁ , P ₂₂ , P ₂₃ , P ₂₄ , P ₃ i, P ₃₂ have the shape of portions of rings extending over angular sectors, the angle of which is determined to form the two magnetization phases and the two phases of demagnetization on a complete revolution of the magnetic arrangement. The radial arrangement of the magnetic poles and the radial arrangement of the magnetocaloric elements 2 imply that the input of the magnetocaloric elements 2 into the magnetic field of said magnetic poles Pu, P ₁₂ , P ₂₁ , P ₂₂ , P ₂₃ , P ₂₄ , P ₃₁ , P ₃₂ begins with an edge, called the input edge 5, belonging to one of the two extremal faces F of the magnetocaloric elements 2. In the embodiments described, it is the edge of the input of the extremal face located on the inner circle 3 of the crown C which is the first to enter the magnetic field. The invention is not limited to the configuration as illustrated magnetic poles Pu, P ₁₂ , P ₂₁ , P _22; P ₂₃ , P ₂₄ , P ₃₁ , P ₃₂ and supports Si, S ₂ . Thus, the magnetic poles which are represented as having three permanent magnets may comprise a different number of permanent magnets, one for example with different shapes. Similarly, the shape of the magnetic poles may be different from that illustrated, and adapted to the shape and volume of air gaps Ei, E ₂ dictated by the shape of the supports Si, S ₂ and magnetocaloric elements 2 to be subjected to the magnetic field gaps Ei, E ₂ , and the intensity of this magnetic field. The means for circulating the coolant are not shown. They can be in the form of pistons or membranes driven mechanically by a cam itself driven in rotation.

Possibilities of industrial application: It is clear from this description that the invention makes it possible to achieve the goals set, namely to propose a magnetocaloric thermal apparatus having a rotation speed that is as constant and stable as possible, the sound level of which is low, increased life and whose achievement is structurally simple. The invention thus makes it possible to avoid the over-dimensioning of the motor required in the case of large torque variations associated with variations in magnetic forces and makes it possible to increase the average efficiency of said motor and therefore of said apparatus, since an engine consumes more in its high torque range.

Such an apparatus may especially find an industrial as well as a domestic application when it is integrated in a magnetocaloric thermal appliance intended to be used in the field of cooling, air conditioning, tempering, heating or other, at competitive costs and with a small footprint.

The present invention is not limited to the embodiments described but extends to any modification and variation obvious to a person skilled in the art.

Claims

claims

A magnetocaloric thermal apparatus (1, 10, 100, 110) rotatably about a longitudinal axis (L), said thermal apparatus (1, 10, 100, 110) having a magnetic arrangement defining at least two air gaps (Ei , E ₂ ) at least partially superimposed and parallel to each other, and arranged to create in each of said air gaps (Ei, E ₂ ) a variable magnetic field around the longitudinal axis (L), at least two supports (Si, S ₂ ) at least partially superimposed, each placed in the median plane (Pi, P ₂ ) of one of said air gaps (Ei, E ₂ ) and carrying magnetocaloric elements (2) at least partially superimposed between said supports, said magnetic arrangement and said supports (Si, S ₂ ) being in relative displacement relative to one another about the longitudinal axis (L) for subjecting the magnetocaloric elements (2) of each support (Si, S ₂ ) to a magnetic cycle created by the variable magnetic field in the ent refer (Ei, E ₂ ) corresponding, thermal apparatus characterized in that the magnetic arrangement and the supports (Si, S ₂ ) are positioned angularly relative to each other about the longitudinal axis (L) of in order to generate a phase shift between the magnetic cycle undergone by the magnetocaloric elements (2) of one of the supports (Si) in one of the air gaps (Ei) and the magnetic cycle undergone by the magnetocaloric elements of the other support (S ₂ ) in the other gap (E ₂ ) so that the magnetocaloric elements (2) penetrate progressively into the magnetic field of said air gaps (Ei, E ₂ ) and this, continuously between the supports (Si, S ₂ ), the magnetic attraction force obtained being then almost constant 2. Thermal apparatus (1, 10) according to claim 1, characterized in that the magnetic arrangement comprises a first, a second and a third magnetizing structures (SMi, SM ₂ , SM ₃ ), each provided with self ns a pair of magnetic poles (Pu, P ₁₂ ; P ₂₁ , P _22; P ₂₃ , P ₂₄ ; P ₃ i, P ₃₂ ), and successively positioned along the longitudinal axis (L) of the thermal apparatus (1, 10) to define, with their pairs of magnetic poles (Pu, P ₁₂ , P ₂₁ , P _22, P ₂₃ , P ₂₄ , P ₃ i, P ₃₂ ), said air gaps (Ei, E ₂ ) and in that said magnetizing structures (SMi, SM ₂ ,

SM3) are angularly positioned relative to one another about the longitudinal axis (L) so as to generate a magnetic cycle in one of the air gaps (Ei) which is offset by a phase shift angle with respect to the cycle magnetic in the other gap (E ₂ ).

3. Thermal apparatus (1, 10) according to claim 2, characterized in that the first and third magnetizing structures (SMi, SM3) are identical and mounted with an angular offset angle (a) between them corresponding to the phase angle.

4. Thermal apparatus (1, 10) according to claim 3, characterized in that the second magnetizing structure (SM ₂ ) comprises, on the one hand, first magnetic poles (P21, P22), which form a first air gap ( Ei) with the corresponding magnetic poles (Pu, P ₁₂ ) of the first magnetizing structure (SMi) and secondly magnetic second poles (P ₂₃ , P ₂₄ ), which form a second gap (E ₂ ) with the corresponding magnetic poles (P31, P32) of the third magnetizing structure (SM ₃ ), and in that the first magnetic poles (P21, P22) and the second magnetic poles (P ₂₃ , P ₂₄ ) of said second magnetising structure ( SM ₂ ) are mounted with an angular offset angle (a) between them corresponding to the phase angle.

5. Thermal apparatus (1) according to any one of claims 2 to 4, characterized in that the first and the third magnetizing structures (SMi, SM3) are mounted head to tail and angularly offset by an angle (a) corresponding to the phase angle,

in that the first magnetic poles (P21, P22) of the second magnetizing structure (SM ₂ ) have the same magnetization sense as the magnetic poles (Pu, P12) of the first magnetising structure (SMi) with which they cooperate to form the gap (Ei),

in that the second magnetic poles (P ₂₃ , P ₂₄ ) of the second magnetising structure (SM ₂ ) have the same sense of magnetization as the magnetic poles (P ₃₁ , P32) of the third magnetizing structure (SM ₃ ) with which they cooperate to form the gap (E ₂ ),

and in that the direction of magnetization of the first and second magnetic poles (P ₂₁ , P22, P31, P32) is the same to create a single loop (B) for circulating the magnetic flux inside said apparatus (1) passing through said first, second and third magnetizing structures (SMi, SM ₂ , SM ₃ ).

6. Thermal apparatus (10) according to any one of claims 2 to 4, characterized in that the first and third magnetizing structures (SMi, SM3) are mounted opposite and angularly offset by an angle (a) corresponding to the angle of phase shift,

in that the first magnetic poles (P21, P22) of the second magnetizing structure (SM ₂ ) have the same magnetization sense as the magnetic poles (Pu, P12) of the first magnetising structure (SMi) with which they cooperate to forming the air gap (Ei) and creating a first loop (Bi) for circulating the magnetic flux inside said apparatus (10) passing through said first magnetic poles (P21, P22) of the second magnetizing structure (SM ₂ ) and said magnetic poles (Pu, P ₁₂ ) of the first magnetizing structure (SMi),

in that the second magnetic poles (P ₂₃ , P24) of the second magnetizing structure (SM ₂ ) have the same direction of magnetization as the magnetic poles (P31, P32) of the third magnetising structure (SM ₃ ) with which they cooperate to form the air gap (E ₂ ) and to create a second loop (B ₂ ) for circulating the magnetic flux inside said apparatus (10) passing through said second magnetic poles (P ₂₃ , P24) of the second magnetizing structure (SM ₂ ) and said magnetic poles (P31, P32) of the third magnetizing structure (SM ₃ ),

and in that the magnetization direction of the second magnetic poles (P ₂₃ , P24) is opposite to that of the first magnetic poles (P21, P22) so that the magnetic flux flows in the first loop (Bi) in the opposite direction to the flow magnetic circulating in the second loop (B ₂ ).

The thermal apparatus (1, 10) according to any one of claims 1 to 5, characterized in that the magnetocaloric elements (2) are angularly positioned relative to each other on their supports (Si, S ₂ ) at an angle (Θ) and in that the phase shift angle is less than 1 angle (Θ) between two adjacent magnetocaloric elements (2).

8. Thermal device (1, 10) according to any one of the preceding claims, characterized in that the supports (Si, S ₂ ) are geometrically identical and arranged parallel to each other in the air gaps (Ei, E ₂ ) corresponding, without angular offset.

9. Thermal apparatus (100, 110) according to claim 1, characterized in that the supports (Si, S ₂ ) are geometrically identical, arranged parallel to each other in the air gaps (Ei, E ₂ ) corresponding, and angularly offset the relative to each other by an angle (β) corresponding to the phase shift angle.

10. Thermal apparatus (100, 110) according to claim 9, characterized in that the magnetocaloric elements (2) are angularly positioned relative to one another on their supports (Si, S ₂ ) at an angle ( Θ) and in that the angular offset (β) between the two supports (Si, S ₂ ) is smaller than the angle (Θ) between two adjacent magnetocaloric elements (2).

11. Thermal apparatus (100, 110) according to any one of claims 9 to 10, characterized in that the magnetic arrangement comprises a first, a second and a third magnetizing structures (SMi, SM ₂ , SM ₃ ), positioned successively along the longitudinal axis (L), and defining, with their magnetic poles (Pu, P ₁₂ , P ₂₁ , P _22, P23, P24, P31, P32) aligned and mounted in two opposite directions of magnetization, a first (Ei) and a second (E ₂ ) gaps.

Thermal apparatus (1, 10, 100, 110) according to one of the preceding claims, characterized in that the magnetocaloric elements (2) comprise N rectangular parallelepipeds provided with magnetocaloric material and arranged in a ring-shaped zone (C) of said support (Si, S ₂ ), said ring (C) being centered on the longitudinal axis (L).

13. Thermal apparatus (1, 10, 100, 110) according to claim 12, characterized in that said ring (C) is defined by two concentric circles, said inner circle and outer circle (3, 4), in that two of the opposite faces of the rectangular parallelepipeds forming said magnetocaloric elements (2) said end faces (F) are each tangent to one of said concentric circles, and in that the longitudinal median axes of two adjacent magnetocaloric elements (2) form between them said angle (Θ) equal to 360 / N degrees.

14. Thermal apparatus according to claim 13, characterized in that the magnetic poles (Pu, P ₁₂ , P ₂₁ , P ₂₂ , P ₂₃ , P ₂₄ , P 31, P 32) have the shape of ring portions extending over angular sectors. whose angle is determined so that the input of the magnetocaloric elements (2) in the magnetic field of said magnetic poles begins with a stop belonging to one of said end faces (F).

15. Thermal apparatus (1, 10, 100, 110) according to any one of the preceding claims, characterized in that the magnetocaloric elements (2) are positioned radially on said support (Si, S ₂ ).

16. Thermal apparatus (1, 10, 100, 110) according to claim 2, characterized in that the magnetic poles (Pu, P ₁₂ , P21, P22, P23, P24, P31, P32) of each magnetizing structure (SMi , SM2, SM3) are identical, but mounted in two opposite directions of magnetization.