Thermomagnetic motor with segmented rotor

Abstract

A thermomagnetic motor includes: a first stator part, a second stator part, a plurality of permanent magnets, and a rotor assembly. The rotor assembly includes: a shaft, a first rotor body, a second rotor body, and a first plurality of thermomagnetic segments. The first rotor body and the second rotor body define first cutouts and second cutouts respectively. The first rotor body and the first stator part collectively define a first cavity. The second rotor body and the second stator part collectively define a second cavity. A first major surface of each of the thermomagnetic segments is exposed to the first cavity via a respective one of the first cutouts. A second major surface of each of the thermomagnetic segments is exposed to the second cavity via a respective one of the second cutouts.

Description

THERMOMAGNETIC MOTOR WITH SEGMENTED ROTORRELATED APPLICATION

[0001] This application claims the benefit of priority to the Singapore application no. 10202402021V filed July 10, 2024, the contents of which are hereby incorporated herein by reference in their entirety for all purposes.TECHNICAL FIELD

[0002] The present disclosure relates to motors and, more particularly, to thermomagnetic motors.BACKGROUND

[0003] The typical power output from thermomagnetic devices is in the range of microwatts to at most hundreds of milliwatts. The limited power density achievable is perplexing and possibly at least partially attributable to various factors. For example, the conventional thermomagnetic device requires the use of a large volume of a thermomagnetic material in order to produce the milliwatts of output power. For example, a high operating temperature is often required in the conventional thermomagnetic device.SUMMARY

[0004] In one aspect, a thermomagnetic motor includes a first stator part; a second stator part; a plurality of permanent magnets disposed on the first stator part; and a rotor assembly. The rotor assembly includes a shaft, a first rotor body, a second rotor body, and a first plurality of thermomagnetic segments. The shaft defines a first axis extending in an axial direction. The rotor assembly is rotatable about the first axis relative to first stator part and the second stator part. The first rotor body defines a first plurality of first cutouts. The first rotor body and the first stator part collectively define a first cavity. The second rotor body define a first plurality of second cutouts. The second rotor body and the second stator part collectively define a second cavity. Each of the first plurality of thermomagnetic segments has a first major surface and a second major surface. The first majorsurface of each of the first plurality of thermomagnetic segments is exposed to the first cavity via a respective one of the first plurality of first cutouts. The second major surface of each of the first plurality of thermomagnetic segments is exposed to the second cavity via a respective one of the first plurality of second cutouts.

[0005] In another aspect, a system includes two or more units of the thermomagnetic motor. The shaft of each of the two or more units of the thermomagnetic motor includes a first shaft component and a second shaft component. The first shaft component extends axially beyond the first stator part and the second shaft component extends axially. The first shaft component of a first of the two or more units of the thermomagnetic motor and the second shaft component of a second of the two or more thermomagnetic motor may be coupled to provide a combined torque output.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Various embodiments of the present disclosure will be described with reference to the following figures:

[0007] FIG. 1 is a schematic diagram showing a thermomagnetic motor according to embodiments of the present disclosure.

[0008] FIG. 2 shows an exploded view of the thermomagnetic motor of FIG. 1.

[0009] FIG. 3 is a schematic diagram of a perspective view of the rotor assembly of the thermomagnetic motor.

[0010] FIG. 4 shows an exploded view of the rotor assembly of FIG. 3.

[0011] FIG. 5 is an image of a prototype of the thermomagnetic motor with the magnetic assembly removed.

[0012] FIG. 6 illustrates the magnetic fields of the permanent magnets relative to the magnetic fields of the thermomagnetic segments of the rotor assembly.

[0013] FIG. 7 is an illustration of multiple units of the thermomagnetic motor being capable of being coupled together.

[0014] FIG. 8 is a schematic illustration of a motor-to-motor coupling.

[0015] FIG. 9 is a schematic diagram of one unit of the thermomagnetic motor.

[0016] FIG. 10 and FIG. 11 are images of various prototypes of the thermomagnetic motor.

[0017] FIG. 12 is a perspective view of a schematic diagram of the first stator part of the thermomagnetic motor.

[0018] FIG. 13 is a schematic illustration of possible air flow paths in the thermomagnetic motor.

[0019] FIG. 14 is a perspective view of the casing assembly of the thermomagnetic motor.

[0020] FIG. 15 shows the casing assembly axially exploded to better illustrate possible water flow paths.

[0021] FIG. 16 is an image of the casing assembly.

[0022] FIG. 17 is an image of the reservoir sump of the casing assembly.

[0023] FIG. 18 shows the temperature of the thermomagnetic segments relative to the respective rotational position.

[0024] FIG. 19A illustrates an alternating heating and cooling zone arrangement for a clockwise rotation under peak positive torque.

[0025] FIG. 19B illustrates an alternating heating and cooling zone arrangement for a counterclockwise rotation under peak negative torque.

[0026] FIG. 20 a pattern of alternating spot heating (or localized heating) and spot cooling (or localized cooling) in the thermomagnetic motor.

[0027] FIG. 21 are images of an experimental set-up to measure mechanical output characteristics of the proposed thermomagnetic motor.

[0028] FIG. 22 shows the experimental results in the form of speed, torque, and power.

[0029] FIG. 23 shows various examples of different numbers of thermomagnetic segments.

[0030] FIG. 24 is a cross-sectional view of a part of the thermomagnetic motor and a corresponding temperature map or heat map.

[0031] FIG. 25 is another cross-sectional view of a part of the thermomagnetic motor and a corresponding temperature map or heat map.

[0032] FIG. 26 are additional simulations of the cooling effect of the air flow.

[0033] FIG. 27 is a schematic diagram showing that at any one time instant, alternate ones of the thermomagnetic segments are cooled and other alternate ones of the thermomagnetic segments are heated.

[0034] FIG. 28 shows the temperature response of the thermomagnetic segments and the rate of heating and cooling achievable per cycle of heating and cooling.

[0035] FIG. 29 and FIG. 30 show the hot water flow and the corresponding temperature distribution in accordance with embodiments of the present disclosure.

[0036] FIG. 31 and FIG. 32 show the cool air flow and the corresponding temperature distribution in accordance with embodiments of the present disclosure.

[0037] FIG. 33 is a schematic diagram of a method to make a thermomagnetic material suitable for use in the thermomagnetic motor of the present disclosure.

[0038] FIG. 34A, FIG. 34B, and FIG. 34C show results of characterization tests performed on thermomagnetic segments of the present disclosure.DETAILED DESCRIPTION

[0039] The following detailed description is made with reference to the accompanying drawings, showing details and embodiments of the present disclosure for the purposes of illustration and to aid understanding, and not to be limiting. Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments, even if not explicitly described in these other embodiments. Additions and / or combinations and / or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0040] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0041] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0042] As used herein, the singular ‘a’ and ‘an’ may be construed as including the plural “one or more” unless apparent from the context to be otherwise.

[0043] The terms "about" and "approximately" as applied to a stated numeric value encompasses the exact value and a reasonable variance as will be understood by one of ordinary skill in the art, and the terms “generally” and“substantially” are to be understood in a comparable manner, unless otherwise specified.

[0044] Some processes may be described in terms of steps merely to aid understanding and / or for convenient reference. The delineation between one step and another step may be described as such merely for convenient reference in the present disclosure. It will be understood that in actual implementation there may not be a clear division or transition from one step to another subsequent step. There may be a certain amount of overlap among the steps and / or more than one step may occur or be performed concurrently in time, etc.

[0045] As used herein, the term “concurrent”, or “concurrently”, is used loosely to refer to two or more occurrences (or events) that at least partially overlap in time. The occurrences may or may not start at the same time instant and / or end at the same time instant.

[0046] Terms such as “first” and “second” are used in the description and claims only for the sake of brevity and clarity, and do not necessarily imply a priority or order, unless required by the context.

[0047] FIG. 1 is a schematic diagram showing a thermomagnetic motor 200 according to embodiments of the present disclosure. FIG. 2 shows an exploded view of the thermomagnetic motor 200 of FIG. 1. The thermomagnetic motor 200 may be described as a motor including an assembly of a magnetic assembly 300, a rotor assembly 400, and a casing assembly 500.

[0048] An axial direction or a first axis 101 may be defined by a shaft 700 of the thermomagnetic motor 200.

[0049] The magnetic assembly 300 includes a plurality of permanent magnets 310 coupled to a first stator part 320. In the present disclosure, the stator includes the first stator part 320 and the permanent magnets 310 coupled to the first stator part 320. The stator may further include a second stator part 520.

[0050] The permanent magnets 310 are disposed in a circle. Each permanent magnet 310 is characterized by a magnetization direction 110. Adjacent permanent magnets 310 have opposite magnetization directions 110. For example, a first permanent magnet has a first axial magnetization direction 113 and a second permanent magnet has a second axial magnetization direction 115, in which thefirst permanent magnet and the second permanent magnet are disposed to orientate the first axial magnetization direction 113 and the second axial magnetization direction 115 in parallel and opposite directions.

[0051] In the example shown, an even number of permanent magnets 310 are radially distributed relative to a center of the first stator part 320. The number of permanent magnets 310 in one thermomagnetic motor 200 may vary from one embodiment to another.

[0052] In some embodiments, each permanent magnet 310 may include a pair of permanent magnet components that are coupled to one another.

[0053] In some embodiments, each permanent magnet 310 may include a magnet coupled with pair of flanges. The flanges may be made of a non-magnetic material suitable for having screw holes formed therethrough. The flanges advantageously enable the permanent magnets to be coupled to the first stator part 320.

[0054] The casing assembly 500 includes a second stator part 520 coupled with a reservoir sump 510.

[0055] The rotor assembly 400 may be fixedly coupled to the shaft 700. The rotor assembly 400 is rotatably coupled to the magnetic assembly 300 via a first bearing coupling 403 between the shaft 700 and the magnetic assembly 300. The first stator part 320 may house the first bearing coupling 403 and also provide support to the rotor assembly 400. The rotor assembly 400 is rotatable relative to the first stator part 320. The rotor assembly 400 is rotatably coupled to the casing assembly 500 via a second bearing coupling 405 between the shaft 700 and the casing assembly 500. The rotor assembly 400 is rotatable relative to the second stator part 520.

[0056] In the thermomagnetic motor 200, the rotor assembly 400 is disposed between and proximal to both the first stator part 320 and the second stator part 520. The rotor assembly 400 may be described as having a first rotor side 430 facing the magnetic assembly 300. The rotor assembly 400 may be described as having a second rotor side 450 facing the second stator part 520. The first stator part 320, the rotor assembly 400, and the second stator part 520 may be described as a stacked arrangement. For convenient reference and to aid understanding, the first stator part 320, the rotor assembly 400, and the second stator part 520 may bedescribed as axially stacked. For example, the respective centers of the first stator part 320, the rotor assembly 400, and the second stator part 520 may be aligned along the first axis 101.

[0057] FIG. 3 is a schematic diagram of a perspective view of the rotor assembly 400. The rotor assembly 400 includes a circular part that may be configured with a rotor thickness (tr) dimension that is relatively smaller than its radial (r) dimension. The rotor assembly 400 may appear to include a circular plate-like or a relatively flat part (also referred to hereinafter as a rotor disc 402 for the sake of brevity) coupled to the shaft 700 at the center of the rotor disc 402. The rotor disc 402 defines opposing major surfaces disposed normal to the first axis 101 .

[0058] FIG. 4 shows the rotor assembly 400 of FIG. 3 exploded along the first axis 101 . According to some embodiments, the rotor assembly 400 includes a rotor body 404 and a plurality of thermomagnetic segments 600. The rotor 404 is rotatable about the first axis 101 relative to the magnetic assembly 300.

[0059] In some embodiments, the rotor body 404 includes a first rotor body 410 and a second rotor body 420. In some embodiments, the thermomagnetic segments 600 may be disposed between the first rotor body 410 and the second rotor body 420. In some embodiments, the thermomagnetic segments 600 are coupled to the rotor body 400, with the first rotor body 410 and the second rotor body 420 providing cutouts to expose the thermomagnetic segments 600 on both sides of the rotor assembly 400. The plurality of thermomagnetic segments 600 are disposed in a radial distribution relative to the first axis 101 , with adjacent ones of the thermomagnetic segments being thermally insulated from one another. In some embodiments, the first rotor body 410 and the second rotor body 420 serve to physically space apart adjacent ones of the thermomagnetic segments 600 from each other. In some embodiments, the rotor body 404 itself serve as a thermal insulation between adjacent ones of the thermomagnetic segments 600. The “ring” formed by the thermomagnetic materials would appear as segmented with non- thermomagnetic material between segments of thermomagnetic material. The thermomagnetic motor 200 is therefore described in the present disclosure as having a segmented rotor.

[0060] The shaft 700 may include a first shaft component 710 and a second shaft component 720. The first shaft component 710 and the second shaft component 720 are coupled to the rest of the rotor assembly such that they extend axially (e.g., parallel to the first axis 101 ) beyond the rotor disc 402 in opposite directions.

[0061] An example of one thermomagnetic segment 600 is schematically illustrated in a plan view to better show its geometrical shape. The thermomagnetic segment 600 is configured with a segment thickness ts(which may be alternatively represented as “t_s”). The thermomagnetic segment 600 may have a geometry that is similar to a section of a flat annular ring. Each thermomagnetic segment 600 may be shaped as an arcuate segment. A plurality of similarly dimensioned thermomagnetic segments 600 are disposed equidistant from the center of the rotor assembly 400. The plurality of thermomagnetic segments 600 may be disposed equally spaced apart to form a circular pattern, e g., collectively, the plurality of thermomagnetic segments 600 form an array characterized by a radial symmetry about a center of the array. The thermomagnetic segments 600 may be differently shaped from the example illustrated.

[0062] Solely to aid understanding, an example of the thermomagnetic segment 600 is illustrated. The thermomagnetic segment may be made of Curie materials. Prototypes were built and experiments were conducted in which the thermomagnetic segment was made of CALORIVAC® (available from Vacuumschmelze Gmbh & Co. KG of Hanau, Germany), which is understood to be an alloy having a material composition of LaFeSi.

[0063] The thermomagnetic segment 600 may be in an arc shape. The thermomagnetic segment 600 may be bounded by an inner arcuate side 622, an outer arcuate side 624, and two straight sides 610. The inner arcuate side 622 may be disposed at an inner radial distance nnner (which may be alternatively represented as “r_inner”) relative to the center of the rotor assembly 400 and the outer arcuate side 624 may be disposed at an outer radial distance router (which may be alternatively represented as “r_outer”) relative to the center of the rotor assembly 400. The thermomagnetic segment 600 may be characterized by an angular span 0 (which may be alternatively represented as “theta”).

[0064] To aid understanding and not to be limiting, in one example, the thermomagnetic segment 600 was configured with a segment thickness (ts) of about 0.4 mm (millimeter) and an angular span of about 24° (24 degrees). Each of the thermomagnetic segments 600 was disposed in a rotor assembly with an inner radial distance at about 62 mm and an outer radial distance at about 84 mm, relative to the center of the rotor assembly.

[0065] The rotor disc 402 may be configured to be as thin as possible while having an overall stiffness to avoid warping when rotated in the course of use. According to some embodiments, the body of one of the first rotor body 410 and the second rotor body 420 may provide a stepped surface to receive the other of the first rotor body 410 and the second rotor body 420.

[0066] To aid understanding and not to be limiting, in the example illustrated in FIG. 4, the second rotor body 420 defines a step 425 on an inner major surface 427. In assembly, when the first rotor body 410 is disposed at the inner major surface 427 of the second rotor body 420, the step 425 of the second rotor body 420 mates with a complementary side 415 the first rotor body 410.

[0067] The first rotor body 410 and the second rotor body 420 may be coupled together by one or more fasteners. To aid understanding and not to be limiting, in the example illustrated in FIG. 4, a plurality of fastener holes 419, 429 may be distributed in the first rotor body 410 and the second rotor body 420. Fasteners, such as but not limited to rivets, screws, pins, etc., may be used to engage respective ones of the corresponding fastener holes 419, 429.

[0068] The thermomagnetic segments 600 are exposed in the rotor assembly 400 through a corresponding plurality of cutouts in the first rotor body 410 and in the second rotor body 410. The first rotor body 410 includes a plurality of first cutouts 412 defined by first cutout edges 413. The second rotor body 420 includes a plurality of second cutouts 422 defined by second cutout edges 423. The first cutouts 412 and the second cutouts 423 correspond to the number and the placement of the plurality of thermomagnetic segments 600.

[0069] A recessed border 424 may be defined in the first cutouts 412 and / or in the second cutouts 422. In one example, the second rotor body 420 defines a recessed border 424 around the second cutout 422. The second rotor body 420 isconfigured such that, in assembly, the thermomagnetic segment 600 is supported by the recessed border 424.

[0070] In some embodiments, the thermomagnetic segment 600 may be configured with a segment thickness (ts) similar to the depth of the recessed border 424, enabling the thermomagnetic segment to be disposed on the recessed border 424. The first cutouts 412 and the second cutouts 422 may be of the same size such that each thermomagnetic segment 600 may be clamped (along the sides of the thermomagnetic segments) by the first rotor body 410 and the second rotor body 210.

[0071] FIG. 5 is an image of a prototype of the thermomagnetic motor of the present disclosure, with the magnetic assembly removed, leaving the rotor assembly disposed in the casing assembly. In the example shown, the rotor assembly sits in the casing assembly, and the second stator part 520 and the first rotor body 410 are visible. It can also be seen that the thermomagnetic segments 600 are exposed through the first cutouts 412.

[0072] In the assembled thermomagnetic motor, the magnetic fields of the permanent magnets 310 and the magnetic fields of the thermomagnetic segments 600 would be proximal to one another, as schematically illustrated in FIG. 6. The permanent magnets 310 may be described as being disposed in a circle in a first plane, and the thermomagnetic segments 600 may be described as being disposed in a circle in a second plane, in which the first plane and the second plane are parallel to one another. The thermomagnetic motor is configured such that the magnetization directions of the permanent magnets are perpendicular to first plane and the second plane. Alternatively described, the first magnetization direction 113 is oriented axially, extending towards the thermomagnetic segments 600, relative to the permanent magnets 310. The second magnetization direction 115 is oriented axially, extending away from the thermomagnetic segments 600, relative to the permanent magnets 310.

[0073] According to embodiments of the present disclosure, the shaft 700 enables multiple units of the thermomagnetic motor 200 to be coupled together to form a motor assembly 202, as illustrated in FIG. 7. Advantageously, the thermomagnetic motors 200 may be axially coupled together to provide a collectiveresultant torque that is higher than the torque achievable by one unit of the thermomagnetic motor 200.

[0074] An example of the motor-to-motor coupling is schematically illustrated in FIG. 8. To avoid obfuscation, two rotor assemblies 400’, 400” are shown in place of the entire units of the motor 200. According to embodiments of the present disclosure, the first shaft component 710 and the second shaft component 720 of different units of the motor 200 are configured to enable coupling with one another. For example, the first shaft component 710 may include a key 712 and the second shaft component 720 may provide a key-way 722. To assemble two motors together, the key 712 of one motor may be inserted into the key-way 722 of another motor. In some examples, the key 712 may include a resiliently compressible element 713. The key 712 may have a greater width in an uncompressed state and a smaller width in a compressed state. When the key 712 is received into the keyway 722, the resiliently compressible element 713 resiliently engages the keyway 722 in a tight fit.

[0075] FIG. 9 is a schematic diagram of one unit of the thermomagnetic motor 200 of the present embodiment. FIG. 10 and FIG. 11 are images of various prototypes of the thermomagnetic motor 200. As shown, a plurality of air inlet ports 340 are distributed around a circumferential side of the first stator part 320. The plurality of air inlet ports 340 are defined between the first stator part 320 and the first rotor side 430 of the rotor assembly 400.

[0076] FIG. 12 is a perspective view of a schematic diagram of the first stator part 320. The first stator part 320 defines a plurality of seats 330. Each seat 330 is sized to receive a permanent magnet 310. The seat 330 may be configured with a pair of magnet supports 332 on which the flanges of the permanent magnets 310 may be disposed. The flanges may be coupled to the magnet supports 332 using, for example but not limited to, fasteners such as screws to couple the permanent magnet 310 to the first stator part 320. The first stator part 320 further defines a stator central hole 360. The stator central hole 360 enables the shaft of the rotor assembly to extend therethrough.

[0077] The seat 330 is configured with a seat opening 334 that would expose the permanent magnet 310 to the first side 430 of the rotor assembly 400. FIG. 13 is aview of the first stator part 320 showing a first stator part inner face 325 as viewed from the first rotor side, schematically illustrating air flow paths 350 between the first stator part 320 and the first side of the rotor assembly.

[0078] The thermomagnetic motor 200 may be configured such that, in operation, air is provided or supplied into thermomagnetic motor 200 via the air inlet ports 340 along air flow paths 351 . The air may then circulate in a first cavity between the rotor assembly (e.g., along air flow paths 353). The stator central hole 360 also serves as an air outlet for the air to exit the first cavity.

[0079] FIG. 14 is a perspective view of the casing assembly 500 and FIG. 15 shows the casing assembly 500 axially exploded to better illustrate possible water flow paths 550. FIG. 16 is an image of the casing assembly and FIG. 17 is an image of the reservoir sump 510. A plurality of water inlet ports 540 are distributed about a circumferential side of the second stator part 520. Each water inlet port 540 may lead to an inner water inlet 542 in the second stator part 520. The inner water inlets 542 are preferably configured as nozzles to produce a water jet directed towards the second side of the rotor assembly. The second stator part 520 further defines a plurality of second stator openings 530. In the thermomagnetic motor 200, a second cavity is defined between the rotor assembly 400 and the second stator part 520. The second stator openings 530 enable fluid communication between the second cavity and a third space. The third space may be defined between the second stator part 520 and the reservoir sump 510. The casing assembly 510 defines a plurality of water discharge ports 560 distributed around a circumferential side of the reservoir sump 510.

[0080] The thermomagnetic motor 200 may be configured such that, in operation, water is provided or supplied into thermomagnetic motor 200 via the water inlet ports 540 along water flow paths 551 . The water may enter the second cavity via the inner water inlets 542 along water flow paths 552. Internal channels in the second stator part 520 were shaped to provide a nozzle, producing a water jet 552. In the second cavity, the water is directed towards the thermomagnetic segments as water jets 552. The water impinges onto the rotor assembly body before the water flows out of the second cavity, along water flow paths 554, into the third space. The water may then exit the reservoir sump 510 (and thethermomagnetic motor 200) via water discharge ports 560, along water flow paths 555.

[0081] Experimental Results

[0082] Prototypes of the thermomagnetic motor 200 were fabricated and tested.

[0083] In the prototypes, the permanent magnets were assembled in a northsouth pairing, e g., with the magnetic poles oriented axially “inwards” and “outwards" in an alternate arrangement. It was found that this allowed for a greater concentration of the magnetic field in the region surrounding the permanent magnets, as well as in the area where the rotor assembly 400 was located.

[0084] The first stator part 320 was made with embedded internal channels to direct air to the first side of the rotor assembly. The air was supplied via a set of inlet ports on the external surface of the upper stator and directed inwards parallel to the top surface of the rotor. It was observed that air could flow in and out of the first cavity in the course of interactions (in operation) between the first stator part and the rotor. The air may be supplied by a pressurized air source and the return air (air exiting the thermomagnetic motor 200) discharged to the surrounding. The moving air facilitates dissipation of any excess heat that may have accumulated at the thermomagnetic segments.

[0085] The first rotor body 410 and the second rotor body 420 may be made of non-magnetic materials, e g. aluminium, high temperature resistant plastics, etc. The second rotor body 420 may serve to provide support to the thermomagnetic segments 600. The first rotor body 410 and the second rotor body 420 sandwiched the thermomagnetic segments 600 to form a rigid body. In the prototype, the ‘pockets’ or cut-outs (e.g., collectively, the first cutouts 412 and the second cutouts 422) in the rotor body (e g., collectively, the first rotor body 410 and the second rotor body 420) enable the thermomagnetic segments 600 to sit tightly in position when the rotor assembly 400 was assembled. The rotor assembly was supported on one side by the first bearing coupling the other side by the lower bearings which seats inside the casing assembly.

[0086] The thermomagnetic segments may be of various dimensions. In the prototypes, a segment thickness (ts) of about 0.4 mm was found to be sufficientlythin to provide a small enough thermal mass and enabling a sufficiently fast rate at which the thermomagnetic segment 600 could alternately heat up and cool down.

[0087] In one example, the rotor assembly 400 included a total of 12 pieces of the thermomagnetic segments.

[0088] There were also internal channels provided within the second stator part. In the experiments, hot water was supplied through the second stator part 520 and directed towards a bottom surface of the thermomagnetic segments (e.g., hot water was directed at the second rotor side of the rotor assembly 400).

[0089] The hot water was supplied via the water inlets ports of the second stator part 520. A plurality of internal channels in the second stator part re-directed the hot water through a set of nozzles so that the hot water impinged on the second rotor side of the rotor assembly 400. The hot water could thus impinge a surface of the thermomagnetic segments 600 and thereby transfer heat to the thermomagnetic segments in the process. Any excess hot water could be discharged into the reservoir sump through a series of openings in the second stator part. The expended hot water was then allowed to flow out of the reservoir sump 510 through water discharge ports. In a closed or recirculating system, at least some if not all of the water discharged could be returned to the hot water source (in a closed recirculating system).

[0090] In the manner described above, the temperature experienced by each of the thermomagnetic segments will change according to its respective rotational position (FIG. 18). The cooler (cooled) thermomagnetic segments 601 would be more strongly attracted by the permanent magnets. The warmer (heated) thermomagnetic segments 603 would be less attracted by the permanent magnets. The alternately hot and cool segments produce a net positive torque. This leads to an alternating heating and cooling zone arrangement relative to the permanent magnets, as illustrated in FIG. 19A (clockwise rotation under peak positive torque) and FIG. 19B (counterclockwise rotation under peak negative torque). The eventual torque that is produced by the thermomagnetic motor still depends on the temperature that can be attained under dynamic conditions. The segments will be in motion once the torque is produced, and this rotation does have an effect on theamount of heating or cooling experienced by each segment of thermomagnetic material.

[0091] The air (cooling) inlet ports and the (heating) inner water inlets alternately disposed are therefore effective in producing alternate heated zones and cooled zones on the rotor assembly 400 as illustrated in FIG. 20. FIG. 20 also shows that the proposed thermomagnetic motor 200 could achieve a pattern of alternating spot heating (or localized heating) and spot cooling (or localized cooling).

[0092] FIG. 21 are images of an experimental set-up to measure mechanical output characteristics of the proposed thermomagnetic motor 200. Pressurized air was supplied to the thermomagnetic motor 200 via the air supply ports. A hot water manifold was used to provide a hot water supply to the thermomagnetic motor 200 and to receive a hot water return from the thermomagnetic motor 200.

[0093] FIG. 22 shows the experimental results in the form of plots over time (seconds) showing the speed (in revolutions per minute), torque (Newton -meter), and power (Watts). The rotor assembly 400 is driven by the torque generated due to changes in reluctance of the thermomagnetic material of the thermomagnetic segments. The reluctance torque that is generated on the rotor is a function of the magnetic flux density on the rotor surface. The flux generated is in turn dependent on the permeability of the thermomagnetic material as well as the position of the thermomagnetic segment relative to the permanent magnet. The rotor dynamics may be described by the following relation assuming that only viscous friction is present:where J is the inertia of the rotating mass and viscous friction is expressed as a function of the rotation speed (co) and friction coefficient (6). The final rotor speed (speed of rotation of the rotor assembly) is dependent on the reluctance torque generated and also the friction acting on the rotor.

[0094] Other experiments conducted included simulating the thermomagnetic motor 200 with different numbers of rotor assemblies stacked together to produce different levels of the mean torque. Yet other experiments conducted included simulating the thermomagnetic motor 200 with different numbers ofthermomagnetic segments (e.g., FIG. 23), for example, using embodiments with eight thermomagnetic segments, 10 thermomagnetic segments, and twelve thermomagnetic segments, respectively, to produce different rotational speed. For example, the rotational speed can be increased by reducing the number of thermomagnetic segments. For example, the mean torque level can be increased by stacking on more units of the thermomagnetic motor 200. The experiments verified that the torque output and the speed output of the proposed thermomagnetic motor 200 are scalable.

[0095] FIG. 24 is a cross-sectional view of a part of the thermomagnetic motor and a corresponding temperature map or heat map. The thermomagnetic segment 600 is disposed between a first cavity 390 and a second cavity 590. Air flow paths 350 in the first cavity 390 are directed by the configuration of the first stator part 320 and the rotor assembly 400 to over a surface of the thermomagnetic segment 600, producing a cooling effect on the thermomagnetic segment 600.

[0096] FIG. 25 is a cross-sectional view of a part of the thermomagnetic motor and a corresponding temperature map or heat map. The thermomagnetic segment 600 is disposed between a first cavity 390 and a second cavity 590. Heated water is directed along water flow paths 550 in the second cavity 590 by the configuration of (the internal channels of) the stator part 320. The resulting water jets 552 are directed axially toward and impinge on the rotor assembly 400 and the surface of the thermomagnetic segment 600, producing a heating effect on the thermomagnetic segment 600 (see, e.g., hot water flow and temperature maps of FIG. 29 and FIG. 30).

[0097] Comparing the original color temperature maps of FIG. 24 and FIG. 25, it would have been apparent that the cooling effect of the air flow could cool the thermomagnetic segment to a temperature around 40 °C (degrees Celsius), and that the heating effect of the water flow could heat the thermomagnetic segment to a temperature of about 45 °C and above (see, e.g., cool air flow and temperature maps of FIG. 31 and FIG. 32).

[0098] FIG. 26 are additional simulations of the cooling effect of the air flow. It could be seen that the airflow may also be provided as air jets directed transversely across the first stator part or the rotor assembly. For the purpose of the presentdisclosure, a transverse direction refers to a direction that is perpendicular or substantially perpendicular to the axial direction.

[0099] As illustrated in FIG. 27, in some embodiments, the thermomagnetic motor 200 includes a plurality of thermomagnetic segments 600, in which at any one time instant, alternate ones of the thermomagnetic segments 600 are cooled by transversely directed cooling fluid (e.g., air) and other alternate ones of the thermomagnetic segments 600 are heated by axially directed heating fluid (e.g., water).

[0100] FIG. 28 shows temperature response of the thermomagnetic segments and the rate of heating and cooling achievable per cycle of the cooling fluid (e.g., air) and the heating fluid (e.g., water). The solid lines in the plots indicate average values and the dotted lines or dashed lines indicate spot temperature values. The total heat transfer per cycle of heating is 49 W and the total heat transfer per cycle of cooling is 21 W.

[0101] Alternatively described, a thermomagnetic motor is presented, the thermomagnetic motor includes a rotor assembly rotatable about an axial shaft. The rotor assembly includes a first rotor plate (e.g., first rotor body) having multiple first cutouts; a second rotor plate (e.g., second rotor body) having multiple second cutouts; and multiple thermomagnetic segments. Each thermomagnetic segment is aligned between respective ones of the first cutouts and the second cutouts, disposed normal to the axial shaft. Each thermo-magnet segment is a single thin layer of a Curie material. The thermomagnetic motor further includes a stator. The stator includes: a first stator part and a second stator part disposed on either side of the rotor assembly. The first stator part defines a plurality of first fluid flow paths, each first fluid flow path extending from a respective air inlet port across a corresponding first cutout of a first thermomagnetic segment, and the second stator part defines a plurality of second fluid flow paths, each second fluid flow path extending from a respective water inlet port to a respective water jet directed towards a corresponding second cutout of a second thermomagnetic segment, the second fluid flow paths being distinct and insulated from the first fluid flow paths. A plurality of the first thermomagnetic segment and a plurality of the second thermomagnetic segments are alternately disposed. The motor further includesplurality of permanent magnets disposed in the first stator part with alternately opposite axial magnetization directions.

[0102] The thermomagnetic motor as described above advantageously provides a scalable mechanical output, e g., a scalable mean torque level and a scalable rotational speed, which enables the thermomagnetic motor to be modular. For example, the thermomagnetic motor may be segmented and stackable, with the speed levels and the torque level scalable with the number of thermomagnetic segments, and with the mean torque proportional to the number of units of the thermomagnetic motor deployed and connected in series.

[0103] The thermomagnetic motor as described above also advantageously enables rapid heating and cooling of the Curie material (provided in the form of the thermomagnetic segments). The configuration of the thermomagnetic motor facilitates spot heating (concentrated heating) using heated (e.g., hot) water jets, while requiring a low capacity cooling (low pressure air source at 20 °C), and provides more an efficient transfer of heat to the Curie material.

[0104] Other Benefits

[0105] The thermomagnetic motor of the present disclosure can be used in harvesting industrial waste energy. An example is shown in Table 1 below. Based on the configuration shown, using thermomagnetic segments made of a Curie material having a Curie temperature of 42 °C, a mechanical power output of 140 W is potentially recoverable from a waste heat source of 7kW, with a relative small amount of additional power (e g., water pump of about 40W and an air pump / fan of about 5 W), with 6.86 kW as waste heat. The potential energy savings is calculated to be about 880 kWh per year of about $262 savings per year (assuming a rate of $0.30 / kWh).Table 1 .

[0106] The thermomagnetic motor of the present disclosure is therefore capable of readily harvesting energy from low temperature heat sources (e.g., below 50 °C) and finds a broad range of practical applications in thermal power plants, solar thermal energy, and geothermal energy management, etc.

[0107] The thermomagnetic motor of the present disclosure further advantageously enables low temperature heat energy harvesting, e.g., in which the thermomagnetic effects can be activated by hot water of at least 47 °C. This means that only a low capacity heat is required, e.g., water flow of at least 3 LPM (litres per minute.

[0108] It can be understood from the foregoing description that the thermomagnetic motor of the present disclosure is capable of operating within a relatively manageable temperature range, e.g., about 37 °C to about 47 °C). The air / water supply systems required to operate the thermomagnetic motor can therefore be more compact and more feasible for practical implementation.

[0109] The amount of thermomagnetic material or Curie material required is relatively small. This would enable the thermomagnetic motor to be economically more viable for widespread use.

[0110] Prototypes of the thermomagnetic segments of the present disclosure were also built and tested in which the thermomagnetic material had a material composition of Mn2FeSn. FIG. 33 schematically shows a method of making the thermomagnetic segments. Manganese, iron, and tin (Mn2FeSn) dry powders were subjected to low energy ball milling. Mechanical alloying was carried out with a powderball ratio of 1 :10, in the presence of 10% ethanol and subjected to 200 revolutions per minute of mixing for 20 hours. The mixture was then subjected to a first heat treatment in hydrogen at 800 °C for 5 hours. The resulting material wascompacted using a weight of 5 tons for one minute into the desired shape. The compacted material (in the shape of the thermomagnetic segments) was subjected to a second heat treatment in an inert environment (e.g., helium or argon atmosphere) at a temperature within the range from 900 °C to 960 °C, from about 2 hours to about 5 hours.

[0111] As shown in FIG. 34A to FIG. 34C, characterization tests demonstrated that the resulting material had properties suitable for use as thermomagnetic segments of the present disclosure.

[0112] According to various embodiments of the present disclosure, in one aspect, a thermomagnetic motor includes a first stator part; a second stator part; a plurality of permanent magnets disposed on the first stator part; and a rotor assembly. The rotor assembly includes a shaft, a first rotor body, a second rotor body, and a first plurality of thermomagnetic segments. The shaft defines a first axis extending in an axial direction. The rotor assembly is rotatable about the first axis relative to first stator part and the second stator part. The first rotor body defines a first plurality of first cutouts. The first rotor body and the first stator part collectively define a first cavity. The second rotor body define a first plurality of second cutouts. The second rotor body and the second stator part collectively define a second cavity. Each of the first plurality of thermomagnetic segments has a first major surface and a second major surface. The first major surface of each of the first plurality of thermomagnetic segments is exposed to the first cavity via a respective one of the first plurality of first cutouts. The second major surface of each of the first plurality of thermomagnetic segments is exposed to the second cavity via a respective one of the first plurality of second cutouts.

[0113] The first plurality of thermomagnetic segments may be spaced apart and thermally insulated from one another by the first rotor body and the second rotor body.

[0114] The thermomagnetic segments may be coupled between the first rotor body and the second rotor body.

[0115] At least one of the first rotor body and the second rotor body may define a recessed border. Each of the first plurality of thermomagnetic segments may be supported by the respective recessed border.

[0116] The first stator part may include a second plurality of air inlet ports distributed along a circumferential side of the first stator part, in which the first cavity provides for a second plurality of air flow paths extending from the plurality of air inlet ports exit in transverse directions relative to the axial direction, across the first major surface of alternately disposed ones of the thermomagnetic segments.

[0117] A center part of the first stator part may define an air outlet port, in which the second plurality of air flow paths exit the first cavity via the air outlet port.

[0118] The second stator part may include a second plurality of water inlet ports and a second plurality of nozzles in the second cavity. The second stator part may define a second plurality of water flow paths from the second plurality of water inlet ports to the second plurality of nozzles. The second plurality of nozzles may be axially oriented to provide a second plurality of water jets directed towards the second major surface of other alternately disposed ones of the thermomagnetic segments.

[0119] Each of the second plurality of water flow paths and the second plurality of air flow paths may interface with different ones of the thermomagnetic segments.

[0120] The thermomagnetic motor may further include a reservoir sump. The reservoir sump may be coupled with the second stator part, in which the reservoir sump is in fluid communication with the second cavity.

[0121] Adjacent ones of the plurality of permanent magnets may be characterized by opposite and axially oriented magnetization directions.

[0122] Each of the first plurality of thermomagnetic segments may be characterized by a Curie temperature of 42 °C.

[0123] The thermomagnetic segments may be made of any one of LaFeSi and Mn2FeSn.

[0124] In operation, air of a room temperature may be provided to the first cavity, and water may be provided to the second cavity, in which the water is heated to a water temperature higher than the Curie temperature of the thermomagnetic segments.

[0125] In operation, alternate ones of the thermomagnetic segments may be heated by the water to a temperature higher than the Curie temperature, and otheralternate ones of the thermomagnetic segments may be cooled by the air to a temperature below the Curie temperature.

[0126] According to various embodiments of the present disclosure, in another aspect, a system includes two or more units of the thermomagnetic motor. The shaft of each of the two or more units of the thermomagnetic motor includes a first shaft component and a second shaft component. The first shaft component extends axially beyond the first stator part and the second shaft component extends axially. The first shaft component of a first of the two or more units of the thermomagnetic motor and the second shaft component of a second of the two or more thermomagnetic motor may be coupled to provide a combined torque output.

[0127] All examples and embodiments described herein, whether of apparatus, methods, materials, or products, are presented for the purpose of illustration and to aid understanding and are not intended to be limiting or exhaustive. Modifications may be made by one of ordinary skilled in the art without departing from the scope of the application as claimed.

Claims

CLAIMS1 . A thermomagnetic motor comprising: a first stator part; a second stator part; a plurality of permanent magnets disposed on the first stator part; and a rotor assembly, the rotor assembly including: a shaft, the shaft defining a first axis extending in an axial direction, the rotor assembly being rotatable about the first axis relative to first stator part and the second stator part, a first rotor body, the first rotor body defining a first plurality of first cutouts, the first rotor body and the first stator part collectively defining a first cavity; a second rotor body, the second rotor body defining a first plurality of second cutouts, the second rotor body and the second stator part collectively defining a second cavity; and a first plurality of thermomagnetic segments, each of the first plurality of thermomagnetic segments having a first major surface and a second major surface, wherein the first major surface of each of the first plurality of thermomagnetic segments is exposed to the first cavity via a respective one of the first plurality of first cutouts, and wherein the second major surface of each of the first plurality of thermomagnetic segments is exposed to the second cavity via a respective one of the first plurality of second cutouts.

2. The thermomagnetic motor as recited in claim 1 , wherein the first plurality of thermomagnetic segments are spaced apart and thermally insulated from one another by the first rotor body and the second rotor body.

3. The thermomagnetic motor as recited in claim 1 , wherein the thermomagnetic segments are coupled between the first rotor body and the second rotor body.

4. The thermomagnetic motor as recited in claim 3, wherein at least one of the first rotor body and the second rotor body defines a recessed border, and wherein eachof the first plurality of thermomagnetic segments is supported by the respective recessed border.

5. The thermomagnetic motor as recited in claim 4, wherein the first stator part comprises a second plurality of air inlet ports distributed along a circumferential side of the first stator part, and wherein the first cavity provides for a second plurality of air flow paths extending from the plurality of air inlet ports exit in transverse directions relative to the axial direction, across the first major surface of alternately disposed ones of the thermomagnetic segments.

6. The thermomagnetic motor as recited in claim 5, wherein a center part of the first stator part defines an air outlet port, and wherein the second plurality of air flow paths exit the first cavity via the air outlet port.

7. The thermomagnetic motor as recited in claim 5, wherein the second stator part comprises a second plurality of water inlet ports and a second plurality of nozzles in the second cavity, the second stator part defining a second plurality of water flow paths from the second plurality of water inlet ports to the second plurality of nozzles, the second plurality of nozzles being axially oriented to provide a second plurality of water jets directed towards the second major surface of other alternately disposed ones of the thermomagnetic segments.

8. The thermomagnetic motor as recited in claim 7, wherein each of the second plurality of water flow paths and the second plurality of air flow paths interface with different ones of the thermomagnetic segments.

9. The thermomagnetic motor as recited in claim 7, further comprising a reservoir sump, the reservoir sump being coupled with the second stator part, wherein the reservoir sump is in fluid communication with the second cavity.

10. The thermomagnetic motor as recited in claim 1 , wherein adjacent ones of the plurality of permanent magnets are characterized by opposite and axially oriented magnetization directions.

11. The thermomagnetic motor as recited in claim 1 , wherein each of the first plurality of thermomagnetic segments is characterized by a Curie temperature of 42 °C.

12. The thermomagnetic motor as recited in claim 1 , wherein the thermomagnetic segments are made of any one of LaFeSi and Mn2FeSn.

13. The thermomagnetic motor as recited in claim 11 , wherein in operation, air of a room temperature is provided to the first cavity, and water is provided to the second cavity, the water being heated to a water temperature higher than the Curie temperature of the thermomagnetic segments.

14. The thermomagnetic motor as recited in claim 13, wherein in operation, alternate ones of the thermomagnetic segments are heated by the water to a temperature higher than the Curie temperature, and other alternate ones of the thermomagnetic segments are cooled by the air to a temperature below the Curie temperature.

15. A system comprising two or more units of the thermomagnetic motor as recited in any one of claims 1 to 14, wherein the shaft of each of the two or more units of the thermomagnetic motor comprises: a first shaft component, the first shaft component extending axially beyond the first stator part; and a second shaft component, the second shaft component extending axially, and wherein the first shaft component of a first of the two or more units of the thermomagnetic motor and the second shaft component of a second of the two or more thermomagnetic motor are coupled to provide a combined torque output.

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