Phase change material energy harvesting

Abstract

Disclosed is a thermal energy harvesting system comprising a phase change material, a thermal actuator, a mechanical conversion system, and a system for mechanical energy storage. The system converts heat to mechanical energy when a temperature change lets a volume of the phase change material to change, causing an actuation force and thereby a displacement of the thermal actuator, and wherein the mechanical conversion system adapts the displacement of the thermal actuator to mechanical energy storage in the system for mechanical energy storage.

Description

PHASE CHANGE MATERIAL ENERGY HARVESTINGTechnical domain

[0001] This invention relates to an energy harvesting system using a phase change material to convert heat into mechanical energyRelated art

[0002] Already known is an energy harvesting system based on the volume change of a fluid during a change of temperature to power a wristwatch. The system is designed to operate in a typical temperature range between 10° C and 30° C. Energy harvesting systems described in WO2014140779 and WO2020053828 are designed to operate in a typical temperature range from 18°C to 30°C based on a working fluid volumetric temperature expansion or compression. However, this approach has shown some limitations: if the watch is in a stable temperature environment (for example when the watch is worn covered by a sleeve), the daily amount of cumulated temperature variations may not be sufficient for the energy harvesting system to maintain the operation of the wristwatch. On the other side, when the wristwatch is not worn, the harvesting system may be exposed to extreme temperatures (typically from -20°C to 70°C) requiring features to protect the energy harvesting system.

[0003] A torsion pendulum clock based on the same principle operates in between 15° C and 30° C(see for example: https: / / en.wikipedia.org / wiki / Atmos_clock the entire content of which is here incorporated by reference).

[0004] The disadvantage of energy harvesting systems based on fluid expansion is their limited harvesting in the desired temperature range, theirPFLEX-5-PCTpotential sensitivity to large temperature excursions or, for torsion pendulums, their sensitivity to orientation and vibrations.

[0005] Already known are also actuators and motors based on phase changing materials (see for example: https: / / waxmotor.com and https: / / en.wikipedia.org / wiki / Wax_motor the entire contents of which are here incorporated by reference).

[0006] Wax motors have the disadvantage of needing electrical actuation, higher transition temperatures than the transition temperatures applicable for the present invention, and lack of energy storage. Furthermore, they cannot be used for wearables.

[0007] What is needed is an energy harvesting system, for example capable of driving a wristwatch worn during the day and taken off during the night. Such a system may also be used for the powering of a pocket watch, a clock, or for the actuation of diverse auxiliary functions in a wristwatch, in a pocket watch, a clock, or in any wearable item.Short disclosure of the invention

[0008] Therefore, it is an object of the invention to provide an energy harvesting system operating in the range between the human or warmblooded animal body temperature and an ambient temperature, preferably a typical room temperature.

[0009] It is another object of the invention to provide an energy harvesting system capable of energy storage.

[0010] It is yet another object of the invention to provide an energy harvesting system capable of working in conditions in which changes of temperature may last for several hours.PFLEX-5-PCT

[0011] It is another object of the present invention to provide an energy harvesting system adapted to protect a watch movement against the effects of extreme temperatures or temperature variations, such as below 0°C, or below -10°C or even below -20°C, and / or above 50°C or 60°C or even above 70°C.

[0012] It is another object of the present invention to provide an energy harvesting system adapted to alert a watch owner of a prolonged residence at a low temperature, typically for divers or mountaineers.

[0013] This task is solved by providing a thermal energy harvesting system which includes a phase change material, a thermal actuator, a mechanical conversion system, and optionally a system for mechanical energy storage, wherein heat is converted to mechanical energy when a temperature change lets a volume of the phase change material change, causing an actuation force and thereby a displacement of the thermal actuator, and wherein the mechanical conversion system adapts the displacement of the thermal actuator to mechanical energy storage in the system for mechanical energy storage.Short description of the drawings

[0014] The attached drawings represent, by way of example, different embodiments of the invention.• FIG. 1 is a view of a thermal actuator based on a pointed piston squeezed by a volume expansion of the phase changing material in a container acting as pressure chamber.FIG. 2a is a view of an actuator with a piston pushed by a volume expansion of the phase changing material in a container acting as a pressure chamber variable volume.PFLEX-5-PCTFIG. 2b is a view of an actuator with a piston pushed by a deformable diaphragm deformed by the volume expansion of the phase changing material.• FIG. 2c is a view of an actuator with a bellow on a piston compressed by the volume expansion of the phase changing material.• FIG. 3 is a view of an actuator with a bellow on a piston expanded by the solidification of the phase changing material aided by a nucleation site.• FIG. 4 is a graphics of the volume change of a phase changing material versus temperature.• FIG. 5 is a view of an energy harvesting system based on pulleys, wires and springs.• FIG. 6 is a view of an energy harvesting system based on a rack-and- pinion drive and springs.• FIG. 7 is a table of typical water temperatures as a function of depth below the water surface.• FIG.7b represents a thermal actuator with the PCM encapsulated into an elastomer shell according to an embodiment of the present invention.• Fig.8 is a schematic view of a thermal actuator comprising an annular chamber and a circular piston.• Fig.9 is a graphics of the volume change of a phase changing material versus temperature illustrating a typical energy harnessing cycle in aPFLEX-5-PCTthermal actuator according to an embodiment of the present invention.• Fig.10 is a graphics of the volume change of a phase changing material mixture with two solid-liquid phase transitions versus temperature according to an embodiment of the present invention.• Fig.11 is a graphics of the volume change of a phase changing material versus temperature in a spring-loaded PCM actuator allowing a broader solid-liquid temperature transition range, according to an embodiment of the present invention.• Fig.12 is a schematic representation of a spring-loaded actuator according to an embodiment of the present invention.• Fig.13 is a schematic representation of a spring-loaded actuator according to an embodiment of the present invention.• Fig.14 is a schematic representation of a spring-loaded actuator according to an embodiment of the present invention.• Fig.15 is a schematic view of an energy harvesting system comprising a knee-lever system, according to an embodiment of the present invention.• Fig.16 is a schematic view of an energy harvesting system comprising a rotative lever system, according to an embodiment of the present invention.

[0015] Those skilled in the art will appreciate that elements in the Figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, dimensions may be exaggerated relative to other elements to help improve understanding of the invention and itsPFLEX-5-PCTembodiments. Furthermore, when the terms 'first', 'second', and the like are used herein, their use is intended for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. Moreover, relative terms like 'front', 'back', 'top' and 'bottom', and the like in the Description and / or in the claims are not necessarily used for describing exclusive relative position. Those skilled in the art will therefore understand that such terms may be interchangeable with other terms, and that the embodiments described herein are capable of operating in other orientations than those explicitly illustrated or otherwise described.Examples of embodiments of the present invention

[0016] The following description is not intended to limit the scope of the invention in any way as it is exemplary in nature, serving to describe the best mode of the invention known to the inventors as of the filing date hereof. Consequently, changes may be made in the arrangement and / or function of any of the elements described in the exemplary embodiments disclosed herein without departing from the spirit and scope of the invention.

[0017] The energy harvesting system according to this invention addresses the limitations of previous energy harvesting systems caused by uncertain size and duration of temperature variations. The system is particularly suited for the use in wristwatches worn during daytime and taken off at night. This use ensures higher repeatability and predictability as a result of a near constant temperature in the hot condition, near the wrist / body temperature slightly below 37° C, and the room temperature (typically < 25° C) in the cold condition at night. According to this use both hot and cold conditions are likely to last for several hours each. Accordingly, the present energy harvesting system is designed to harness sufficient mechanical energy for at least one day of watch power upon just one single temperature cycle between body temperature and room temperature.

[0018] The thermal energy harvesting system according to this convention includes a phase change material (PCM), a thermal actuator, aPFLEX-5-PCTmechanical conversion system, and optionally a system for mechanical energy storage, wherein heat is converted to mechanical energy when a temperature change lets a volume of the phase change material change, causing an actuation force and thereby a displacement of the thermal actuator, and wherein the mechanical conversion system adapts the displacement of the thermal actuator to mechanical energy storage in the system for mechanical energy storage or to direct use for any mechanical function in the wristwatch.

[0019] For the purpose of the present disclosure, a thermal actuator denotes any system adapted to react under a temperature variation so as to provide a mechanical motion of some neighboring elements, either in direct contact or through indirect mechanical connection. A thermal actuator includes a PCM actuator. In the present disclosure a PCM actuator is meant as an example of a thermal actuator.

[0020] The thermal actuator is designed to minimize the friction of the PCM during its solidification phase transition. Design principles of wax based thermal actuators can be adapted to the invention. The thermal actuator design is made of a rigid pressure chamber with a moving volume feature to transform PCM volume variations into actuator displacement: considering for example a cylindrical piston inserted into an elastomeric boot, the piston is pushed by the boot squeezed by the PCM expansion.

[0021] The thermal actuator may comprise a piston with sliding axial joint, a deformable diaphragm, a deformable bellow or a PCM encapsulated in an elastomer.

[0022] The sliding axial joints (dynamic seals) may comprise or be made of elastomer, a rigid polymer or a combination thereof. Elastomer may be combined with an appropriate lubrication such as the PCM itself, a PCM nonsoluble grease, a dry-lubrication coating such as molybdenum disulfide (MoS₂), Tungsten disulfide (WS₂), Polytetrafluoroethylene (PTFE), Diamon Like Carbon (DLC) or graphite.PFLEX-5-PCT

[0023] Alternatively, the sliding axial joint may denote a hybrid joint comprising for example a combination of an elastomer spring element and a rigid polymer sliding / sealing element, or a combination of a metallic spring and a rigid polymer or elastomer.

[0024] According to an embodiment, one or both of the rod or the chamber are coated. A coating such a low surface energy coating and / or a low friction coating can be used. A low surface energy coating can designate Diamond Like Carbon or PTFE. It is advantageously used to avoid or limit the supercooling of the PCM, by promoting nucleation. It further allows reducing adhesion with the solid PCM. The low friction coating may designate DLC, MoS2, WS2. It reduces the friction between the sliding parts and / or reduces adhesion with the solid PCM.

[0025] Referring now to FIG. 1, a thermal actuator 10 may consist of a pointed piston 12, introduced into a container (pressure chamber) 14 filled with phase changing material 16, 18 which is solid 16 at a low temperature 20 and liquid 18 at a high temperature 22. The volume expansion of the phase changing material upon its melting during a temperature rise exerts a squeezing force onto the pointed tip 24 of the piston 12, trying to push the piston upwards out of the pressure chamber. Conversely, when the volume of the phase changing material shrinks during its solidification caused by a temperature drop, the piston moves downwards 28 again farther into the container. This downward move 28 may have to be aided for example by an external spring which pushes the piston down.

[0026] Referring now to FIG. 2a, a cylindrical piston 212 of an actuator 200 introduced into a container (pressure chamber) 214 with phase changing material 216, 218 may equally be pushed upwards 226 or downwards 228 when the phase changing material liquifies 218 at a high temperature 222 or solidifies 216 at a low temperature 220, respectively, where the downwards motion 228 may again be aided by an external spring.PFLEX-5-PCT

[0027] Referring now to FIG. 2b, a piston 242 of actuator 240 may be pushed upwards 246 by a deforming a deformable diaphragm 254 which separates the phase changing material 266, 268 from the empty part 252 of a container (pressure chamber) 244 when the phase changing material 268 liquifies at a high temperature 222. Here the piston 242 may move down 248 when the deformable diaphragm reverts back into its resting position 256 during the solidification process of the phase changing material 266 at a low temperature 220 without any external help.

[0028] Referring now to FIG. 2c, compressing 274 and expanding 276 a bellow introduced into the container (pressure chamber) 282 of actuator 270 with the phase changing material 286, 288 and attached to a piston 272 may result in a similar piston movement 290, 292 during heating 222 and cooling 220, respectively. The downwards motion 292 during solidification may again have to be aided by an external spring.

[0029] Referring now to FIG. 3, jamming of thermal actuator 300 comprising a piston 312 attached to a bellow 316, 318 may be prevented by introducing a cold bridge or a nucleation site 328 to promote the start of the solidification 330 of the phase changing material 324, 326 at specific locations with regards to the moving part (piston) 312 of the actuator to minimize the contact force with the solidified PCM as the temperature drops from high 322 to low 320. Such a nucleation site 328 may include a lattice structure, a radiator-like structure, low surface energy spots, a coating, or a structure or a microstructuration of any other shape appropriately designed for such a function. For example, solid or liquid additive(s) can be added, for example low surface energy powder such as PTFE, HDPE. Such an additive acts as nucleation sites or thermally conductive particles, in the case of metallic powder, graphite, carbon nanotubes or graphene, or solidlubricants particles in the case of MoS2, WS2. Such a cold bridge or nucleation site further allows to shorten the time response of the thermal actuator and / or prevents the supercooling of the PCM.PFLEX-5-PCT

[0030] According to an embodiment, the watch winding is performed when the thermal actuator is moving forward transitioning from cold condition to hot condition. During this transition, the available mechanical work of the actuator is larger as positive pressure is building up in the thermal actuator case and the PCM internal friction is lower thanks to presence of the liquid phase at the end of the transition.

[0031] According to an embodiment, the watch winding is performed when the thermal actuator is moving backward transitioning from hot condition to cold condition, thanks to a return spring or any other return elastic device, and an inverter mechanism.

[0032] A further variant of a thermal actuator may be or comprise a piston with an axial joint.

[0033] Referring now to FIG. 4, the volume evolution 400 of a phase changing material 404, 406 as a function of temperature 412 may include a small volume increase with rising temperature in the solid phase 404 below the fusion temperature (phase changing temperature) 414, a rapid volume expansion 416 around a fusion temperature 414, and a moderate volume expansion 418 with rising temperature in the liquid phase 406.

[0034] Referring now to FIG. 5, a first embodiment 500 of an energy harvesting system adapted to driving a wristwatch may comprise a moving pulley 512 on an actuator piston or shaft 514 and a wire 516, 518, 524 to transmit the motion 520 of the thermal actuator 510 caused by the liquification of the phase changing material through a static pulley 528 to a gear train 534. One end 522 of the wire 516 is fixed to the frame 530 of the watch for example on the leftside of the actuator 510. The wire 516 is routed upwards from the point of fixation 522 through the moving pulley 512 and then in a parallel direction 518 downwards to be routed through the pulley 528 which is static with respect to the frame 530 of the watch. According to this construction the displacement of the wire at the location of the fixed pulley 528 is twice as large as the displacement 520 of the actuator pistonPFLEX-5-PCT514 (or moving pulley 512). The moving end of the wire is wrapped around the fixed pulley 528 and connected to a spring 526 or any similar elastic device fixed to the frame 530 of the watch. During the volume expansion of the phase changing material and concomitant upward motion 520 of the piston 514 of the actuator, the spring 526 or the similar elastic device exhibits a tensile strain 532, the associated force of which helps moving the actuator back to its original position in the cold state (see for example FIGs 2a, 2c). With the help of a gear train 534 comprising a free wheel 540, the rotation of the fixed pully provides the angular travel and torque enabling mechanical storage by winding a barrel spring 536 or by means of a compression spring, a traction spring, a torsion spring, or any other springlike device able to store mechanical energy in the form of an elastic displacement. The free wheel 540 decouples the barrel spring 536 or any other storage device from the backward motion of the drive train during the solidification of the phase changing material, so that the storage remains unaffected by this motion.

[0035] In an aspect of the embodiment an inverter mechanism may provide energy storage also during the backward motion of the actuator to the cold state of the phase changing material.

[0036] Referring now to FIG. 6, a second embodiment 600 of an energy harvesting system adapted to driving a wristwatch may, instead of the wirebased approach, comprise a rack-and-pinion 624 transmission 622 of the displacement 620 of the piston 614 of the actuator 610 to a fixed pulley 628 and to a spring 626 to generate the tensile strain 632, the other functions comprising for example gear train 634 with free wheel 640 and barrel spring 636 remaining the same.

[0037] Referring to FIG.7b, the thermal actuator comprises a container 714 in which an elastomer shell 730 is arranged. The PCM 718 is encapsulated in the elastomer shell 730. The piston rod 712 is in contact with the elastomer shell 730 so as to move upward 726 upon dilatation of the PCM.PFLEX-5-PCT

[0038] Referring to FIG. 8, the thermal actuator 810 has an annular or semi-annular shape and the piston 814 has a curved shape adapted to slide in the annular shape of the casing. A first 830 and a second 840 bearings can be provided on the piston so as to transmit its rotational movement to other mechanical parts.

[0039] Referring now to FIG. 9, the volume evolution 900 of a phase changing material 904, 906 into a thermal actuator harnessing energy as a function of temperature 912 may include a temperature interval 915 between a first temperature threshold 916 and a second temperature threshold 917. The thermal actuator is activated when the temperature reaches the second temperature threshold 917 in a heating mode 914 and reset when the temperature reaches the first temperature threshold 916 in a cooling mode 913. Such a temperature interval can define an activation interval. The activation interval can be defined as large as possible so as to maximize the density of energy harvested. According to an embodiment, the activation interval equals the operation temperature range. For example, the first temperature threshold 916, corresponding to the solidification may be 25°C and the second temperature threshold 917, corresponding to the fusion may be 31 °C. For such use, the first temperature threshold is set above the room temperature 908, and the second temperature threshold is set below the wrist temperature 910. Within the activation interval, the PCM is transitioning from a fully solidified state to a fully liquid state and the other way round.

[0040] According to an embodiment, energy is harvested with small temperature variations within the operational temperature range 915. Energy can be harvested on room temperature variation or on wrist temperature variation. The activation temperature range 915 of the thermal actuator is preferably smaller than the operation temperature range. Alternatively, the PCM can be in solid-liquid phase equilibrium able to be activated with a smaller temperature interval than the operational temperature range. The displacement of the solid-liquid phase equilibrium thus generates a partial PCM volume variation, allowing to harvest energyPFLEX-5-PCTon a reduced temperature range, with more threshold temperatures within the operational temperature range.

[0041] Alternative mechanical conversion systems from thermal actuators to gear trains may comprise a drive train, a metallic ribbon on pulley, chain & sprocket, rack & pinion, a knee-lever system (Fig. 15), a cam and follower system,

[0042] The phase changing material (PCM) has preferably a fusion temperature between room temperature and a wrist or body temperature. Moreover, it is preferably a material the density of which is very different between its solid and liquid phase. A system using wax as a phase changing material is not suitable for the application in a wristwatch, because of its fusion temperature above 40° C.Suitable materials for the present application may be:a hydrocarbon having from 10 to 30 carbon atoms, preferably from 12 to 25 carbon atoms, linear, branched or cyclic, or a combination of several of such hydrocarbons. Preferred hydrocarbons are :- Octadecane, an alkane with 18 carbon atoms. Octadecane differs from paraffin wax as it is a pure hydrocarbon.- Heptadecane, a 17-carbon atoms (C17) alkane. Heptadecane differs from paraffin wax as it is a pure hydrocarbon- Hexadecane, a 16-carbon atoms (C16) alkane. Hexadecane differs from paraffin wax as it is a pure hydrocarbonOther aliphatic hydrocarbons such as nonadecane & eicosanePFLEX-5-PCTBio-sourced and food-grade phase changing materials such as fatty acids:o Aliphatic acids, for example pure decanoic acid with 10 carbon atoms, with a fusion temperature of 31.65° Co A mixture of decanoic acid (C10) with lauric acid (12 carbon atoms) with a fusion temperature adjustable between 20.6°C and 40.5°C, depending on the fraction of each componentFatty acid esters can be used as non-acidic bio-sourced phase changing materials such as:o Pure methyl palmitate with a fusion temperature of 29.5°C or ethyl palmitate with a fusion temperature of 26°Co Or in combination with methyl stearate (melting point 37°C to 41 °C) or ethyl stearate (34-38°C) to adjust the fusion temperature of the combination.- A PCM Mixture with several liquid-solid temperature transitionso A mixture of any combination of aliphatic hydrocarbons, aliphatic fatty acids or fatty acid esters

[0043] Referring to figure 10, showing the PCM mixture volume 1002 as a function of the temperature 1012, the solid-liquid phase equilibrium 1003 can be achieved by a mixture of different PCMs . A binary PCM composition can have a first phase transition 1016 from a state 1004 where both PCM are solid to a state where one of the PCM is solid and the other one is liquid 1003. The binary PCM composition can have a second transition 1017 temperature toward a state where both PCMs are liquids 1006. The number of transitions could be increased with the number of components in thePFLEX-5-PCTmixture. Several transitions can be obtained through the cooling mode 1013 and / or the heating mode 1014. The transitions preferably occur between the room temperature 1008 and the wrist temperature 1010.

[0044] With reference to figures 11, 12, 13, 14, the energy harvesting system comprises a spring loaded (thermal) actuator. A spring applies a variable pressure proportional to the volume variation of the PCM. Figure 11 shows the volume evolution 1100 of a phase changing material 1104, 1106 as a function of temperature 1112. The spring-loaded actuator PCM volume 1102. The spring stiffness is tuned so that the pressure of the PCM set by the spring is in equilibrium with the solid-liquid PCM 1115 volume, which is in the range between the PCM solidification temperature 1108 and the PCM melting temperature 1110, both depending on the spring-PCM pressure.

[0045] With reference to Figures 12, 13 and 14, the energy harvesting system comprises a spring-loaded actuator 1210, 1310, 1410 allowing the displacement 1220, 1320, 1420, and comprising a spring 1226, 1326, 1426, with the advantage to allow energy harvesting with arbitrary threshold temperatures and / or arbitrary thermal cycles in the solid-liquid equilibrium, as long as the designed thermal activation temperature interval is reached.

[0046]

[0047] Figure 15 shows a further alternative embodiment, producing a non-linear transformation of the movement of a spring-loaded PCM actuator using a knee-lever joint. A spring-loaded actuator 1810 comprising a spring 1826 is combined with an articulated knee-lever joint 1828 so as to provide the movement 1820. The movement 1820 can be directed orthogonally compared to the axis of the spring-loaded actuator. Other angular directions can be considered, depending on the arrangement of the knee-lever joint.

[0048] With regard to figure 16, the thermal actuator 1910 comprised a helical rod piston 1926, anchored on a rotative lever 1928 so as to provide a rotative movement 1920 larger than 180°. ICIPFLEX-5-PCT

[0049] According to one aspect, a large operation temperature range will require a spring with larger stiffness, increasing spring force and PCM pressure at high temperature.

[0050] The above-described embodiments based on spring-loaded actuators may also be applied with non-spring loaded actuators, such as the above-mentioned thermal actuator.

[0051] According to an aspect, the thermal actuator may allow a unidirectional or bidirectional winding of the barrel.Unidirectional down: when moving forward the actuator compresses a spring. When the actuator is moving backward, the spring is expanding, rewinding the barrel. This embodiment has the advantage that the speed of winding can be controlled independently from the temperature changes and deliver the harvested energy when the watch is not worn (in the alternative use case). In this configuration, energy is only released when the watch reaches the lower temperature range of the use case (room temperature).o To optimize further the unidirectional down winding, the timing of the energy release of the spring to rewind the barrel spring of the watch can be adjusted, for example an additional locking mechanism can be added on the spring to release its energy only when the watch barrel reaches a certain amount of unwinding. This can be done with:- a timed trigger that will unlock the large spring after a predefined period has elapsed since the watch has reached room temperature.- a trigger that releases the large spring when the barrel spring torque decreases to a minimum threshold torque- a trigger that releases the large spring when the number of winded turns of the barrel spring decreases to a minimum threshold value.PFLEX-5-PCTBidirectional: when the actuator moves forward, the barrel is wound, and an additional inverter element loads the barrel when the actuator is moving backward pushed by the spring.

[0052] According to an embodiment, the present invention comprises one or more the following features:

[0053] The energy harvesting system for wristwatch takes advantages that the watch is worn during day (hot condition) and not worn at night (cold condition) to harvest mechanical energy to power a wristwatch.

[0054] The thermal actuator is sized to harvested more than 1 day of power reserve over one cycle of cold to hot condition transition followed to a hot to cold condition transition.

[0055] The thermal actuator is based on PCM with a phase change from solid to liquid in the temperature range comprised between the cold condition such as 25°C, 22°C, 20°C, 16°C or below, to hot condition such as 37°C, or 40°C or 42°C or higher) or between a cold condition at 16°C and a hot condition at 37°C.

[0056] The PCM is made of pure or a mixture of Hexadecane, Heptadecane, Octadecane, Nonadecane or Icosane.

[0057] The PCM is alternatively made of pure Decanoic acid or a combination of Decanoic acid & Lauric acid.

[0058] The PCM is made of pure Fatty acid ester pure Methyl palmitate or Ethyl palmitate.

[0059] The PCM is made of a combination of Methyl / Methyl palmitate and Methyl / Ethyl stearate.PFLEX-5-PCT

[0060] The PCM is made of a mixture of any combinations of aliphatic hydrocarbon, aliphatic fatty acid or fatty acid esters

[0061] The PCM is selected so as to not produce gas bubbles during the solid / liquid or liquid / solid phase transitions, thereby ensuring a maximum stiffness of the PCM, which translates into a most efficient force transmission to the mechanical conversion system.

[0062] Energy is harvested on environment temperature fluctuation to power a watch (like for example when not worn, in a display or worn during diving, or in space travel / extra vehicular activity / planetary surface exploration) or to power a clock

[0063] The PCM / thermal actuator can have several activation temperatures.

[0064] Several activation temperatures can be obtained by a mixture of PCMs that allows to have partial solid-liquid phase change within the operational temperature of the PCM actuator.

[0065] Arbitrary activation temperatures can be obtained by loading the PCM / thermal actuator with a tuned-stiffness spring allowing the PCM to be in a solid-liquid equilibrium in a spring-loaded actuator.

[0066] The thermal actuator use case gives a prediction of a hot & cold temperature condition over a time period of 24 hours for a wristwatch.

[0067] The thermal actuator use case gives a prediction of exposition durations to hot & cold durations of the energy harvesting system over a time period of 24 hours.PFLEX-5-PCT

[0068] The predictability of the thermal conditions over a period of 24 hours allows to have a better reliability on the minimum amount of mechanical energy, if the harvesting system is optimized for these conditions.

[0069] The volumetric expansion of the PCM from solid to liquid is much larger than the volumetric thermal expansion of a liquid solution in the watch operational temperature range allowing:a. a more compact harvesting system design thanks to a higher energy density of the PCM compared to previous liquid based Preciflex patents.b. As the solid and liquid thermal expansion of the PCM is much lower than the volumetric expansion due to the solid to liquid phase change in the wristwatch extreme temperature range (- 20°C to 50°C, preferably -20°C to 80°C), the use of the PCM provide an inherent mechanism protection to the thermal actuator for temperature condition out of the typical temperature range.

[0070] The present system is a wearable system, which can work independently of gravity.

[0071] Annular PCM chamber geometry is well suited for integration in a wristwatch.

[0072] The spring-loaded PCM / thermal actuator allows to harvest energy on a smaller temperature variation such as room temperature variation.

[0073] For the purpose of this disclosure, any mixture or combination of the above-mentioned suitable materials has to be understood as being a phase changing material that can be used in the present invention.PFLEX-5-PCT

[0074] Additives may be included in the phase changing material to enhance its properties, for example thermal conductivity, density, viscosity, resistance to radiations, resistance to oxidation, lifetime enhancement, nucleation catalyser, etc.

[0075] The phase changing material energy harvesting system of the application captures temperature differences to generate mechanical energy and presents transformative possibilities for a wide range of mechanical watches. By integrating phase transition materials responsive to specific temperature thresholds, not only the barrel spring can be rewound. It also opens transformative possibilities for enhancing functionalities, introducing new complications, and improving the overall performance and sustainability of mechanical timepieces.

[0076] The present invention relates to a thermal actuator as described above. According to an embodiment, the thermal actuator allows converting temperature variations into mechanical movement exclusively. The mechanical energy may be stored by mean of the above-described mechanical energy storage system. According to another embodiment, the thermal actuator is not used for producing electrical energy. According to another embodiment the thermal actuator is used to convert temperature variations into an electrical power exclusively. According to an embodiment, the thermal actuator allows to convert temperature variations into a combination of mechanical movement and electrical power.

[0077] The present invention further relates to a mechanical horological device such as a mechanical watch, in particular a mechanical wristwatch, a pocket watch, a table clock or a similar timekeeping instrument. The mechanical horological device of the present invention comprises one of the above-described thermal actuator. Such thermal actuator(s) is or are exclusively used or configured to supply mechanical energy to the horological device, or exclusively used or configured to provide electrical power of the horological device, or to provide a combination of electrical power and mechanical energy.PFLEX-5-PCT

[0078] The present invention further covers a method or a process of converting temperature variations within a range of temperatures into a mechanical movement, a mechanical energy, an electrical power or a combination thereof. The method comprises a step of providing at least one thermal actuator as described herein and arranging the same on a support. Such a support may be for example a structural element of an horological device as defined above.

[0079] The method comprises a step of placing said thermal actuator in contact with a mechanical conversion system, with an electrical conversion system or with a combination thereof. Such a contact is adapted so that activation of the thermal actuator by a temperature variation influences said mechanical and / or electrical conversion system.

[0080] The method comprises a further step of placing the thermal actuator in an environment wherein the temperature varies between a lower threshold and an upper threshold. A lower threshold can be for example defined as 22°C, 20°C or 16°C. A second lower threshold may be defined, such as 0°C, -10°C or -20°C. The upper threshold may be defined as 35°C, 37°C, 40°C or 45°C. A second upper threshold may be defined such as 50°C, 60°C, 70°C or even 80°C or higher. The environment may be as mentioned above, for example related to an animal or human temperature variation. Alternatively or in addition, the environment refers to the ambient temperature variations.

[0081] The thermal actuator is configured so that a temperature variation between the lower and the upper thresholds provides a displacement of the thermal actuator or a part it, such as a piston.

[0082] The method comprises a step of converting the displacement of the thermal actuator or a part thereof into mechanical motion of one or more of the mechanical conversion system and the electrical conversion system, preferably exclusively of the mechanical conversion system so as to produce a mechanical movement.PFLEX-5-PCT

[0083] The method may further comprise a step of storing the mechanical energy produced as above-described into a mechanical energy storage system as above-defined, wherein the mechanical energy is transferred from the thermal actuator to the mechanical energy storage device by means of the mechanical conversion system.

[0084] The technology, the thermal actuator and / or the horological device above-mentioned can be applied to various watch types, functions and complications as follows:1. General applications for all mechanical watches• Winding of the barrel spring: The system supplies energy to wind the barrel spring, enabling the watch to function continuously.• By harvesting energy from temperature variations while the watch is worn during the user's active phase and removed during sleep, the system winds the barrel spring without requiring manual winding or relying on kinetic movement.• While this feature is beneficial for everyone and suitable for all conditions, it is particularly advantageous in environments where traditional winding mechanisms face limitations, such as space microgravity or underwater diving.Extending power reserve:• Energy harvesting from temperature variations extends the watch's power reserve.• For example, the need for manual winding or reliance on kinetic movement is reduced, ensuring the watch remains powered even during periods of inactivity.PFLEX-5-PCTPowering additional complications:• Surplus energy can drive complex mechanical functions without depleting the main power reserve.• The system supports intricate complications like perpetual calendars, tourbillons, and minute repeaters, enhancing the watch's functionality and appeal.Automatic function activation:• The system activates functions in response to environmental conditionsProtective mechanisms against extreme temperatures:• The system can protect the watch when extreme or predefined temperatures are reached.• When exposed to excessive heat (e.g., under intense sunlight) or extreme cold (e.g., harsh winter conditions), the system triggers mechanisms to safeguard sensitive components:o Automatic function suspension: Temporarily halts specific complications to prevent damage from thermal stress.o Activation of insulating barriers: Deploys mechanical shutters or insulating layers to shield critical parts of the movement.o Thermal expansion compensation: Adjusts mechanical tolerances to accommodate material expansion or contraction, preserving functionality.PFLEX-5-PCTo User alerts: Provides visual indicators, sound or tactile feedback to inform the wearer of extreme temperature exposure, prompting protective action.Adaptive display modes:• The watch face adjusts its appearance based on temperature ranges, enhancing readability and functionality without relying on electronic displays.• Applications:o Improved Visibility: In low-light or colder conditions, the energy generated by the system of the invention can be coupled with a microgenerator to activate luminescent features or illuminate the dial. This mechanical energy source powers lighting elements that enhance readability without the need for batteries or electronic components.o Visual effects using light: By coupling the system with a microgenerator, the watch can produce captivating light-based visual effects. This could include illuminated logos, indices, or hands that glow or change intensity based on temperature shifts, all powered by mechanical energy.o User notifications: Displays temperature-related information or alerts directly through mechanical means on the watch face. For example, a mechanical indicator could reveal a symbol or change position when certain temperature thresholds are crossed, keeping the wearer informed about environmental conditions without electronic displays.o It is possible to incorporate thermochromic materials or fluidbased indicators in the system that change color or appearance withPFLEX-5-PCTtemperature variations. This creates a unique and engaging visual effect on the dial, providing an interactive experience that reflects environmental changesPersonalized functionality:• Watches can be customized with phase transition materials suited to the user's typical environment.• Example: A watch tailored for desert conditions vs. one for arctic exploration, each responding to different temperature thresholds.2. Applications in specific watch complications

[0085] Thermal activation in chronographs:

[0086] Controlling chronograph functions based on temperature thresholds, enabling the measurement of durations within specific temperature ranges.Minute Repeaters:Activation at temperature thresholds• Triggers chime functions based on specific temperature thresholds.• Can serve as unique auditory alerts for temperature conditions.Alarms:Temperature-triggered alarmsPFLEX-5-PCTAlarms activate when certain temperature thresholds are reached.• Useful for triggering visual effects, visual indications, tactile information, light activation when temperatures rise or fall to a set point.3. Innovative Dive Watch embodiments:

[0087] By utilizing specific phase transition materials adapted to temperature thresholds encountered in diving situations, this technology opens unprecedented possibilities for enhancing dive watches.

[0088] Phase transitions can occur not only between air and water temperatures but also due to temperature differences at varying depths underwater.

[0089] Different actuators designed with distinct temperature thresholds can trigger specific functions, providing a new level of adaptability and functionality in timepieces.Harnessing thermal energy from temperature variations:

[0090] Referring now to FIG. 7, a typical variation of water temperatures as a function of depth below the water level comprises the water zones from a surface layer to the abyssal zone at great depth. The system leverages the natural temperature gradients experienced during a dive. For instance, as a diver descends, water temperature typically decreases, often ranging from surface temperatures of around 20°C (68°F) to depths where temperatures can drop below 5°C (41 °F). These variations enable the phase transition materials within the watch to activate, generating mechanical energy and triggering designated functions.Specific water temperatures when divingPFLEX-5-PCT• Surface to Thermocline Transition: At shallow depths (0-20 meters), temperatures may remain around 20°C (68°F). Beyond this, the thermocline layer introduces a sharp temperature drop.• Deep Water Conditions: At depths exceeding 30 meters, temperatures can fall below 10°C (50°F), providing ample temperature gradients for energy generation and function activation.Significance for watch design:• Customization for diving environments:o Watches can be tailored to specific diving conditions, whether for warm tropical waters or cold temperate seas.o Different phase transition materials allow for multiple functions to be activated at various depths.• Enhanced safety and functionality:o By aligning watch functions with temperature-depth profiles, divers receive timely information and alerts.o Improves overall diving experience and safety through responsive technology.Application in Diving Watches:• Phase Transition Materials:o Materials can be engineered to undergo phase changes at specific temperatures corresponding to typical diving depths.PFLEX-5-PCTo For example, a material that changes state at 15°C would activate around 50 meters, triggering specific watch functions.• Function activation based on depth-related temperatures:o Shallow Dives (0-20 meters): Functions for recreational diving can activate in warmer temperatures.o Moderate Depths (20-50 meters): Transition materials respond to cooler temperatures, enabling features like enhanced displays or safety alerts.o Deep Dives (50-100 meters): Critical functions for technical diving can be triggered by materials responding to temperatures below 10°C.Innovations for dive watches:Specific phase changing materials adapted to diving temperatures:• Customized Materials: Utilizing materials that undergo phase transitions at temperature thresholds common in diving scenarios. This ensures reliable activation of functions at precise moments during a dive.• Temperature- and Depth-Related Activation: By calibrating materials to respond to temperatures at certain depths, the watch can initiate features relevant to those specific underwater environments.Application of different temperature thresholds:PFLEX-5-PCT• Multi-Threshold Devices: Incorporating multiple devices of the system of the invention with varying temperature thresholds allows the watch to perform different functions as the diver experiences different temperatures.• Sequential Activation: Functions can be programmed to activate in sequence as the diver reaches colder waters, enhancing both safety and utility.Adaptive functionality based on temperature ranges and thresholds• Temperature threshold alerts: The system triggers alerts divers when critical temperature thresholds are crossed. For example, visual, tactile or sound notifications activated by the system when entering colder thermoclines, aiding in hypothermia prevention.• Automatic function activation: Dive-specific features are activated automatically by the system at certain temperatures. Application example: A dive timer engages upon submersion in colder water.• Thermal chronograph: Timing functions controlled by the system at certain temperature changes. Application example: Starts or stops timing based on reaching specific temperatures like colder thermoclines, aiding in hypothermia prevention.• Adaptive display modes: The system triggers display to adjust for optimal underwater visibility. Application example: Switches to high-contrast or luminescent mode in low-temperature, low-light conditions.• User health monitoring: The system monitors conditions affecting diver safety. Application example: Alerts for potential hypothermia risks during prolonged exposure to cold temperatures.PFLEX-5-PCT

[0091] The system therefore represents a significant leap forward in horological technology, especially for diver's watches. By integrating materials and mechanisms responsive to specific temperature thresholds encountered during dives, we provide timepieces that are essential companions for the modern diver.4. Innovation platform for future developments

[0092] The technology of the invention serves as a foundation for significant advancements in micro-mechanical engineering. By harnessing environmental energy, it encourages the development of new mechanical complications and mechanisms that can be both miniaturized and innovated upon. This platform pushes the boundaries of what is possible in watchmaking, inspiring engineers to explore novel designs and functionalities powered by ambient temperature differences.

[0093] Moreover, the technology drives research into advanced materials that are responsive to specific temperature thresholds. This focus on material science advancements leads to the creation of more efficient, durable, and responsive components for mechanical watches. By utilizing materials that react predictably and beneficially to temperature changes, watchmakers can enhance the performance and longevity of timepieces, setting new standards in the industry.

[0094] A future research topic will comprise time regulation in extreme temperatures (below -20°C and above +50°C): Advancing the limits for enhanced performance in space, deep-sea diving, and high-altitude mountaineering, such as:Temperature compensation, mitigating the effects of temperature on the escapement:PFLEX-5-PCT• Temperature variations influence the accuracy of mechanical watches. The escapement mechanism, particularly the balance wheel and hairspring, is sensitive to temperature changes due to the physical properties of the materials used. Hairsprings expand and lose elasticity in heat, making the watch run slower, while contraction in cold increases elasticity, causing the watch to run faster.• Alloys like Nivarox significantly reduce these effects by maintaining stable elasticity and low thermal expansion. However, temperature can still slightly impact timekeeping due to other factors like lubrication viscosity or case design.• Passive methods are most effective in the range of -10°C to +40°C for standard watches and up to -20°C to +50°C for high-performance models. Beyond these ranges, timekeeping accuracy degrades, and active compensation like the system of the invention can offer solutions needed to maintain performance.Improving timekeeping precision through advanced engineering:The integration of the system of the invention can offer a novel approach to mitigating temperature-induced inaccuracies in mechanical watches in extreme temperatures:• Active Temperature Compensation: By harnessing energy from ambient temperature differences, the system of the invention can drive compensatory mechanisms that adjust the tension of the hairspring or modify the effective length of the balance spring in response to temperature changes. This active compensation maintains consistent oscillation periods of the balance wheel, preserving accurate timekeeping.• Isolation of the escapement: The system can activate insulating barriers or micro-shutters that regulate thermal exposure of the escapement.PFLEX-5-PCTBy maintaining a stable microclimate around the sensitive components, the system minimizes the impact of external temperature fluctuations.• Dynamic adjustment mechanisms: Mechanical linkages powered by the system of the invention can adjust the position of timing screws or variable inertia weights on the balance wheel. These adjustments counterbalance the changes in mass distribution due to thermal expansion, maintaining the balance wheel's moment of inertia.

[0095] The exploration of time regulation in extreme temperatures highlights the significant potential of the system of the invention. By mitigating temperature-induced inaccuracies through advanced engineering, The system extends the operational limits of mechanical watches. It ensures consistent timekeeping precision even under extreme conditions, thereby expanding the applicability of mechanical watches to new frontiers. This technology preserves the integrity of the watch's movement but also exemplifies how innovative solutions can address longstanding challenges in horology.

[0096] In essence, the system of the invention serves as a cornerstone for future developments, inspiring watchmakers and engineers to push the boundaries of what is possible. It invites a reimagining of design and functionality, encouraging the creation of timepieces that are not only marvels of engineering but also reliable companions in the most demanding environments. Through this innovative platform, the watch industry can achieve new heights in performance, precision, and sustainability.5. Sustainability and environmental impact

[0097] The technology of the system of the invention positions the watch industry as a leader in sustainable practices by utilizing ambient temperature differences to power mechanical functions.PFLEX-5-PCT

[0098] This innovation not only benefits the environment but also offers substantial marketing advantages. Watches become eco-friendly, renewable energy-powered devices that appeal to environmentally conscious consumers. Emphasizing the watch's ability to harness natural temperature variations enhances its appeal to a growing segment of eco-aware customers, differentiating the brand in a competitive market.

[0099] By integrating the system of the invention into various types of mechanical watches, a new frontier of innovation is opened that enhances functionality, accuracy, and user engagement. The system's ability to wind the barrel spring ensures continuous operation, while its capacity employ phase transition materials allow for a multitude of advanced features.

[0100] Importantly, the system can actively protect the watch in extreme temperature conditions and adapt the watch face through mechanical means for optimal readability and functionality. By coupling the system with a microgenerator, captivating visual effects can be created using light powered by mechanical energy, enhancing both aesthetics and practicality without relying on electronic displays.

[0101] The system of the invention provides practical benefits across a wide array of applications and aligns with a growing emphasis on sustainability and environmental consciousness. Whether through powering complex complications, adapting to environmental conditions, protecting the watch from extreme temperatures, or offering unique aesthetic features, the possibilities are vast and transformative.

[0102] The horological community is invited to explore these opportunities, leveraging the technology platform of the system of the invention to create timepieces that are not only marvels of engineering but also companions attuned to the world around us.PFLEX-5-PCT

[0103] The invention can be summarized as including elements selected from one or a portion of one of the appended claims or one or a portion of one of the following feature sets:1. The thermal energy harvesting system, wherein the combination of (a) a phase changing material (16, 18, 216, 218, 266, 268, 286, 288, 324, 326), (b) a thermal actuator (10, 200, 240, 270, 300, 510, 610), (c) a mechanical conversion system (512, 516, 518, 524, 526, 528, 534, 540, 624, 632, 628, 634, 640), and optionally (d) a system for mechanical energy storage (536, 636), is used to convert heat into mechanical energy when a temperature change causes a volume of the phase changing material (26, 28, 226, 228, 246, 248, 290, 292, 520, 620) to change, causing an actuation force and thereby a displacement of the thermal actuator, and wherein the mechanical conversion system adapts the displacement of the thermal actuator to mechanical energy storage in the system for mechanical energy storage or to direct use for actuating mechanical functions.2. The thermal energy harvesting system of feature set 1, wherein the phase changing material (16, 18, 216, 218, 266, 268, 286, 288, 324, 326) is adapted to a temperature variation between a human or warm blooded animal wrist or body temperature and an ambient temperature, preferably a room temperature, and wherein the phase changing material is mainly in a solid phase at the ambient or room temperature and mainly in a liquid phase at a wrist or body temperature.3. The thermal energy harvesting system of feature set 1, wherein the displacement of the thermal actuator which is at least based on a piston (12, 212, 242 272, 312, 514, 614) is a linear (26, 28, 226, 228, 246, 248, 290, 292) or a rotary motion or a combination of a linear and a rotary motion (520, 550, 620, 622).4. The thermal energy harvesting system of feature set 1, wherein the mechanical conversion system is selected from a list of mechanical conversion systems, comprising at least:PFLEX-5-PCTa. a system comprising at least a moving (512) and a static pulley (528, 628), a wire (516, 518, 524) and a spring element (526) to transmit the displacement of the thermal actuator motion to a gear train communicating with the system for mechanical energy storage,b. a system comprising at least a rack-and-pinion drive (624) and a spring (626) to transmit the displacement of the thermal actuator motion to a gear train communicating with the system for mechanical energy storage,c. a system comprising a crank and connecting rod.5. The thermal energy harvesting system of feature set 1, wherein the system for mechanical energy storage is selected from a list of mechanical energy storage systems, comprising at least:a. a barrel spring (536, 636),b. a compression spring,c. a traction spring,d. a torsion spring,e. a flexion spring.6. The thermal energy harvesting system of feature set 1, wherein the phase changing material is contained in a container acting as a pressure chamber (14, 214, 244, 282, 314), and wherein the volume change (416) between a solid phase (404) and a liquid phase (406) of the phase changing material is much larger than the volume change (418) of a liquid subject toPFLEX-5-PCTa similar temperature change, and wherein the thermal actuator transforms the volume change of the phase changing material into a displacement.7. The thermal energy harvesting system of feature set 1, wherein the phase changing material is a material of a list of materials comprising at least:a. Hexadecane, Heptadecane, Octadecane, Nonadecane & Eicosaneb. Aliphatic acids, comprising pure decanoic acid or a mixture of decanoic and lauric acid,c. Fatty acid esters, comprising pure methyl palmitate or pure ethyl palmitate, or in combination with methyl stearate or ethyl stearate.d. a mixture of a, b or c.8. The thermal energy harvesting system of feature set 1, wherein the system for mechanical energy storage provides the energy for powering a wearable device subject to be worn in any orientation.9. The thermal energy harvesting system of feature set 1, wherein the system for mechanical energy storage provides the energy for powering the movement of a mechanical watch.10. A mechanical watch powered at least in part by the energy harvesting system of any of the preceding feature sets.11. A mechanical wristwatch powered at least in part by the energy harvesting system of any of the preceding feature sets.PFLEX-5-PCT12. The mechanical watch of feature set 9, wherein the energy supplied by the thermal energy harvesting system to a barrel spring enables the watch to function continuously without requiring any manual winding or kinetic movement.13. The mechanical watch of feature set 12, wherein surplus energy supplied by the thermal energy harvesting system can drive complex mechanical functions and enhance a functionality of the watch.14. The mechanical watch of feature set 13, wherein at least one protective mechanism from a list of protecting mechanisms protects the watch against extreme temperatures, the list comprising at least:a. an automatic function suspension,b. an activation of insulating barriers,c. a thermal expansion compensation,d. a provision of visual, sound or tactile feedback to alert a wearer of the watch.15. The mechanical watch of feature set 14, wherein an appearance of a watch face is adjusted to a range of temperatures to provide readability and functionality without relying on any electronic displays, wherein the appearance enables at least an application from a list of applications, comprising at leaste. providing an improved visibility in low-light or colder conditions by activating luminescent features or by illuminating a dial,PFLEX-5-PCTf. coupling the thermal energy harvesting system to a microgenerator to generate light-based visual effects, including illuminating logos, indices or hands that glow or change intensity based on temperature shifts,g. providing temperature-related information or alerts by mechanical means on the watch face,h. incorporating thermochromic materials or fluid-based indicators that change color or appearance upon a change of temperature.16. The mechanical watch of feature set 15, wherein phase changing materials are adapted to thresholds encountered in diving situations.17. The mechanical watch of feature set 16, wherein the phase changing materials are customized to undergo phase changes at temperature thresholds prevailing in common diving scenarios.18. The mechanical watch of feature set 17 comprising multiple phase changing materials with different temperature thresholds, permitting the watch to perform different functions depending on a temperature experienced by a diver.19. The mechanical watch of feature set, wherein the multiple phase changing materials change phase sequentially to provide safety and utility as a diver reaches colder and colder waters.20. The mechanical watch of feature set 15, wherein a time regulation is adapted to extreme temperatures, permitting at least one application from a list of applications, comprisingi. applications in space,PFLEX-5-PCTj. applications in deep-sea diving,k. applications in high-altitude mountaineering.21. The mechanical watch of feature set 20, wherein temperature compensation mitigates the effect of temperature on an escapement.

[0104] In an advantage, the invention provides an energy harvesting system operating in the range between the human body temperature and room temperature or environment temperature variations.

[0105] In another advantage, the invention provides an energy harvesting system capable of energy storage.

[0106] In still another advantage, the invention provides an energy harvesting system capable of working in conditions in which changes of temperature may last for several hours.

[0107] It should be appreciated that the particular implementations shown and herein described are representative of the invention and its best mode and are not intended to limit the scope of the present invention in any way.

[0108] The specification and figures should be considered in an illustrative manner, rather than a restrictive one and all modifications described herein are intended to be included within the scope of the invention claimed. Accordingly, the scope of the invention should be determined by the appended claims (as they currently exist or as later amended or added, and their legal equivalents) rather than by merely the examples described above. Steps recited in any method or process claims, unless otherwise expressly stated, may be executed in any order and are not limited to the specific order presented in any claim. Further, the elements and / or components recited in apparatus claims may be assembled orPFLEX-5-PCTotherwise functionally configured in a variety of permutations to produce substantially the same result as the present invention. Consequently, the invention should not be interpreted as being limited to the specific configuration recited in the claims.

[0109] Benefits, other advantages and solutions mentioned herein are not to be construed as critical, required or essential features or components of any or all the claims.

[0110] As used herein, the terms "comprises", "comprising", or variations thereof, are intended to refer to a non-exclusive listing of elements, such that any apparatus, process, method, article, or composition of the invention that comprises a list of elements, that does not include only those elements recited, but may also include other elements such as those described in the instant specification. Unless otherwise explicitly stated, the use of the term "consisting" or "consisting of" or "consisting essentially of" is not intended to limit the scope of the invention to the enumerated elements named thereafter, unless otherwise indicated. Other combinations and / or modifications of the above-described elements, materials or structures used in the practice of the present invention may be varied or adapted by the skilled artisan to other designs without departing from the general principles of the invention.

[0111] The patents and articles mentioned above are hereby incorporated by reference herein, unless otherwise noted, to the extent that the same are not inconsistent with this disclosure.

[0112] Other characteristics and modes of execution of the invention are described in the appended claims.

[0113] Further, the invention should be considered as comprising all possible combinations of every feature described in the instant specification, appended claims, and / or drawing figures which may be considered new, inventive and industrially applicable.PFLEX-5-PCT

[0114] Additional features and functionality of the invention are described in the claims appended hereto and / or in the abstract. Such claims and / or abstract are hereby incorporated in their entirety by reference thereto in this specification and should be considered as part of the application as filed.

[0115] Multiple variations and modifications are possible in the embodiments of the invention described here. Although certain illustrative embodiments of the invention have been shown and described here, a wide range of changes, modifications, and substitutions is contemplated in the foregoing disclosure. While the above description contains many specific details, these should not be construed as limitations on the scope of the invention, but rather exemplify one or another preferred embodiment thereof. In some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the foregoing description be construed broadly and understood as being illustrative only, the spirit and scope of the invention being limited only by the claims which ultimately issue in this application.

[0116] In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.PFLEX-5-PCT

Claims

Claims1. A thermal energy harvesting system comprising:a) at least one phase changing material (PCM),b) a thermal actuator andc) a mechanical conversion system,wherein a temperature variation is converted to mechanical energy when a temperature change causes a volume of the phase changing material to change, causing an actuation force and thereby a displacement (26, 28, 226, 228, 246, 248, 290, 292, 520, 620) of the thermal actuator.

2. Thermal harvesting system according to claim 1, further comprising a system for mechanical energy storage (536, 636), wherein the mechanical conversion system converts the displacement of the thermal actuator to mechanical energy storage in the system for mechanical energy storage or to direct use for actuating mechanical functions.

3. Thermal harvesting system according to one of claims 1 and 2, wherein said thermal actuator is adapted to be fixed to a support in mechanical contact to said mechanical conversion system so that said temperature variation is converted exclusively into mechanical energy.

4. Thermal harvesting system according to one of claims 1 to 3, wherein said support denotes a structural element of an horological device.PFLEX-5-PCT5. The thermal energy harvesting system according to one of claims 1 to 4, wherein the phase changing material is adapted to a temperature variation between a human or warm blooded animal wrist or body temperature and an ambient temperature, preferably a room temperature, and wherein the phase changing material is mainly in a solid phase at the ambient or room temperature and mainly in a liquid phase at a wrist or body temperature.

6. The thermal energy harvesting system of one of claims 1 to 5, wherein the phase changing material is adapted to a temperature variation of its environment, and wherein the phase changing material is mainly in a solid phase at a lower environment temperature and mainly in a liquid phase at a higher environment temperature, wherein the environment excludes a human or warm blooded animal wrist or body temperature.

7. The thermal energy harvesting system of one of claims 1 to 6, wherein the thermal actuator comprises a piston, (12, 212, 242 272, 312, 514, 614) so that said displacement is linear (26, 28, 226, 228, 246, 248, 290, 292) or a rotary motion or a combination of a linear and a rotary motion (520, 550, 620, 622).

8. The thermal energy harvesting system of one of claims 1 to 7, wherein the mechanical conversion system is selected from a list of mechanical conversion systems, comprising at least:a. a system comprising at least a moving (512) and a static pulley (528, 628), a wire or any other flexible transmission element (belt, ribbon, chain) (516, 518, 524) and a spring element (526) to transmit the displacement of the thermal actuator motion to a free wheel and a gear train communicating with the system for mechanical energy storage or with a further mechanism for immediate use,b. a system comprising a rack-and-pinion drive (624) and a spring (626) to transmit the displacement of the thermal actuatorPFLEX-5-PCTmotion to a free wheel and a gear train communicating with the system for mechanical energy storage or with a further mechanism for immediate use,c. a system comprising a crank and connecting rod.

9. The thermal energy harvesting system of one of claims 2 to 8, wherein the system for mechanical energy storage is selected from a list of mechanical energy storage systems, comprising at least:a. a barrel spring (536, 636),b. a compression spring,c. a traction spring,d. a torsion spring,e. a flexion spring.

10. The thermal energy harvesting system according to one of claims 1 to 9, wherein the phase changing material is contained in a container acting as a pressure chamber (14, 214, 244, 282, 314), and wherein the volume change (416) between a solid phase (404) and a liquid phase (406) of the phase changing material is larger than the volume change (418) of a liquid subject to a similar temperature change, and wherein the thermal actuator transforms the volume change of the phase changing material into a displacement.

11. The thermal energy harvesting system according to one of claims 1 to 10, further comprising a nucleation site adapted to promote the start of the solidification of the phase changing material.PFLEX-5-PCT12. The thermal energy harvesting system according to one of claims 1 to 11, further comprising a spring-loaded actuator, wherein the thermal actuator is provide with a spring so as to allow energy harvesting with arbitrary threshold temperatures and / or thermal cycles in the solid-liquid equilibrium.

13. The thermal energy harvesting system according to one of claims 1 to 12, wherein the phase changing material is a material of a list of materials comprising at least:a. a hydrocarbon having from 10 to 30 carbon atoms, preferably from 12 to 25 carbon atoms, linear, branched or cyclic, or a combination of several of such hydrocarbonsb. Aliphatic acids, comprising pure decanoic acid or a mixture of decanoic and lauric acid,c. Fatty acid esters, comprising pure methyl palmitate or pure ethyl palmitate, or in combination with methyl stearate or ethyl stearate.d. Any mixture of a, b, c.

14. The thermal energy harvesting system according to one of claims 2 to 13, wherein the system for mechanical energy storage provides the energy for powering a wearable device subject to be worn in any orientation.

15. The thermal energy harvesting system according to one of claims 2 to 13, wherein the system for mechanical energy storage provides the energy for powering the movement of a mechanical watch.

16. The thermal energy harvesting system according to one of claims 1 to 15, wherein said thermal actuator denotes a spring-loaded actuator, comprisingPFLEX-5-PCTat least one spring adapted to apply a pressure to the PCM proportional to the PCM volume variation.

17. The thermal energy harvesting system according to claim 16, said lever being of the type of Knee-lever or rotative lever.

18. A mechanical horological device, comprising a thermal energy harvesting system according to one of claims 1 to 17.

19. Mechanical horological device according to claim 18, wherein said horological device denotes a mechanical watch powered at least in part by said energy harvesting system.

20. Mechanical horological device according to one of claims 18 and 19, wherein said horological device denotes a mechanical watch powered by said energy harvesting system, wherein said harvested energy is used exclusively for mechanical functions in the horological device.

21. Mechanical horological device, according to one of claims 19 and 20 wherein the mechanical watch defines a mechanical wristwatch.

22. Mechanical horological device according to one of claims 19 to 21, further comprising a barrel spring, wherein the energy supplied by the thermal energy harvesting system to the barrel spring enables the watch to function continuously without requiring any manual winding or kinetic movement.

23. Mechanical horological device according to one of claims 19 to 22, wherein energy supplied by the thermal energy harvesting system is further adapted to drive complex mechanical functions and enhance a functionality of the watch.

24. Mechanical horological device according to one of claims 19 to 23, wherein at least one protective mechanism from a list of protectingPFLEX-5-PCTmechanisms protects the watch against extreme temperatures, the list comprising at leasta. an automatic function suspension,b. an activation of insulating barriers,c. a thermal expansion compensation,d. providing visual, sound or tactile feedback to alert a wearer of the watch.

25. Mechanical horological device according to one of claims 19 to 24, wherein an appearance of a watch face is adjusted to a range of temperatures to provide readability and functionality without relying on any electronic displays, wherein the appearance enables at least on application from a list of applications, comprising at leasta. providing an improved visibility in low-light or colder conditions by activating luminescent features or by illuminating a dial,b. coupling the thermal energy harvesting system to a microgenerator to generate light-based visual effects, including illuminating logos, indices or hands that glow or change intensity based on temperature shifts,c. providing temperature-related information or alerts by mechanical means on the watch face,PFLEX-5-PCTd. incorporating thermochromic materials or fluid-based indicators that change color or appearance upon a change of temperature.

26. Mechanical horological device according to one of claims 19 to 25, wherein phase changing materials are adapted to thresholds encountered in diving situations.

27. Mechanical horological device according to one of claims 19 to 26, wherein the phase changing materials are customized to undergo phase changes at temperature thresholds prevailing in common diving scenarios.

28. Mechanical horological device according to one of claims 19 to 27 comprising several multiple phase changing materials with different temperature thresholds, permitting the watch to perform different functions depending on a temperature experienced by a diver.

29. Mechanical horological device according to one of claims 19 to 28, wherein several multiple phase changing materials change phase sequentially to provide safety and utility as a diver reaches colder and colder waters.

30. Mechanical horological device according to one of claims 19 to 29, further comprising a time regulation adapted to extreme temperatures, permitting at least one application from a list of applications, comprisinga. applications in space,b. applications in deep-sea diving,c. applications in high-altitude mountaineering.PFLEX-5-PCT31. Mechanical horological device according to one of claims 19 to 30, further comprising a temperature compensation adapted to mitigate the effect of temperature on an escapement.

32. A method of converting temperature variations within a temperature range into a mechanical movement and / or mechanical energy, by mean of the thermal actuator according to one of claims 1 to 17. The method comprising the step of:a) Arranging one or several of said thermal actuator on a support,b) Placing said thermal actuator in contact with a mechanical conversion system,c) Placing said thermal actuator in an environment wherein the temperature varies between a lower threshold and an upper threshold, so that the temperature variation provides a displacement of the thermal actuator or a part it andd) Converting the displacement into mechanical move of the mechanical conversion system.

33. A method according to claim 32, said support being a structural element of an horological devicePFLEX-5-PCT

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