Driving system for mechanocaloric heating or cooling apparatus

Abstract

A driving system (100), in particular for a mechanocaloric heating, cooling or dehumidifying apparatus, the driving system (100) comprising: an arrangement with at least a first set and a second set of mechanocaloric elements, wherein each set comprises at least one mechanocaloric element (120), each mechanocaloric element (120) comprising at least one mechanocaloric material, and a loading system (140), which is configured to load and unload the first set and the second set of mechanocaloric elements (120) in a plurality of consecutive operational cycles by applying a deformation, in particular a shape or volume change, to the at least one mechanocaloric element (120), and wherein, in each operational cycle, the loading system (140) is configured to cyclically load and unload the first and second set of mechanocaloric elements (120), such that during a respective loading phase of the first and second set of mechanocaloric elements an at least approximately constant mechanical input power is applied on the mechanocaloric elements (120), and such that during a respective unloading phase of the first and second set of mechanocaloric elements an at least approximately constant mechanical output power is applied from the mechanocaloric elements (120) on the loading system (140).

Description

[0001] DRIVING SYSTEM FOR MECHANOCALORIC HEATING OR COOLING APPARATUS

[0002] The present disclosure relates to a driving system for a mechanocaloric heating, cooling or / and dehumidifying apparatus. Mechanocaloric cooling and heat pump technologies, which includes elastocaloric and barocaloric technologies, are utilizing entropy / temperature changes of ferroic and / or caloric materials and, are recognized as one of the most promising alternatives to the widely used vapor-compression cooling and heating technology.

[0003] Mechanocaloric cooling and heating have the potential to reduce the environmental impact of cooling and heating primarily due to the use of solid refrigerants that do not harm the ozone layer or contribute to the greenhouse effect and are completely safe for humans (e.g. they are non-toxic and non-flammable) and can also be recycled after usage.

[0004] There are multiple different types of caloric effects, e.g. magnetocaloric effect, electrocaloric effect, and mechanocaloric effect, which includes barocaloric effect and elastocaloric effect.

[0005] The elastocaloric effect occurs when an elastocaloric material is subjected to mechanical loading (uniaxial or multiaxial), leading to deviatoric strain - deformation of material as a change of shape. If these strains are sufficiently large, they induce and entropy change and / or a phase transformation of the material, resulting in the heat release. Consequently, the material heats up (above ambient temperature), and this heat is transferred to the surroundings as the material stabilizes at the initial ambient temperature. Upon unloading, the material undergoes a reverse transition, consuming energy, which cools the material (below ambient temperature) and allows it to absorb heat from the surroundings.

[0006] Similarly, the barocaloric effect occurs when a barocaloric material is exposed to external hydrostatic pressure, causing volumetric strains - deformation of material as a change of volume. This strain triggers an entropy change and / or phase transformation, releasing heat and heating the material under pressure. During decompression, the reverse transition occurs, absorbing energy, which cools the material (below ambient temperature) and enables it to take in heat from the surroundings.

[0007] The barocaloric materials and the elastocaloric materials are referred to as mechanocaloric materials as they are subject to the caloric effect upon mechanical loading and unloading by an external mechanical load (force, pressure, torque etc) and / or deformation (changes of shape and / or volume) which induces mechanical stresses and strains in the material.

[0008] The cyclic exposure of these caloric materials to external loads and / or deformations enables efficient heating or cooling, leveraging the caloric phenomenon for applications in heat pumps or cooling devices.

[0009] Despite the significant potential of mechanocaloric technology, it faces severaldevelopmental challenges that are crucial for successful market breakthrough. Current development and research focus on mechanocaloric materials, improving the efficiency of mechanocaloric regenerators, ensuring durable operation, developing drive systems, and manufacturing mechanocaloric devices themselves. A mechanocaloric regenerator is a porous structure made of mechanocaloric material through which a heat transfer fluid is pumped in a counterflow direction. It works both as a refrigerant and regenerator and enables an increase of the temperature span between the heat sink and heat source, which can be several times larger than adiabatic temperature changes of the material. This enables the utulization of modest caloric effects in practical devices where a temperature span of 30K or more are ussualy required.

[0010] Active mechanocaloric regenerators (or mechanocaloric elements in general) are recognized as a key element for exploiting the mechanocaloric effect in practical applications, presenting a challenge on how to ensure sufficiently large mechanical loads for driving (loading and unloading) these regenerators.

[0011] One of the key challenges is thus the drive system of mechanocaloric technology, as the technology requires a special approach to ensure efficiency and optimal energy (work) utilization during the loading and unloading of mechanocaloric regenerators or elements, where the released energy (work) during unloading is returned to the system, as well as the constant and continuous input power supply needed for its operation (e.g. the loading and unloading of the regenerators / elements). Efficient reuse of energy released during unloading is crucial for achieving high efficiency and, similarly, providing energy to the mechanocaloric regenerators / elements during loading in an efficient way is crucial as well.

[0012] The need for a constant and continuous input power supply is related to the size (volume and mass) of the system required for operation, which directly impacts the production and operational costs of the technology as well as the size of the system. Actuators, which must meet specific force and displacement requirements to achieve the desired mechanocaloric effect, are typically used for loading mechanocaloric regenerators / elements in lab-scale setups. Hydraulic actuators, known for their high output force, have been used in recently published prototypes. Electromechanical motors in combination with different mechanisms are currently the most widespread actuators in mechanocaloric systems. Research further focuses on optimizing and improving the efficiency of these actuators, including the development of SMA (Shape Memory Alloy) actuators. Despite these advancements, further research is needed to develop more efficient and optimized actuators / drivers for practical use in mechanocaloric cooling.US20220228575A1 discloses an elastocaloric energy converter comprising multiple elastocaloric elements and a loading device, wherein the loading device cyclically actuates the elastocaloric elements in a way that the elastocaloric elements are subject to a loading phase, hold phases and an unloading phase, and wherein the loading device actuates the different elastocaloric elements in a phase-offset manner with respect to their respective cyclic loading and unloading phases.

[0013] This disclosure aims at providing an advanced driving system.

[0014] SUMMARY

[0015] A first aspect relates to a driving system, in particular for a mechanocaloric heating, cooling and / or dehumidifying apparatus. The driving system comprising an arrangement with at least a first set and a second set of mechanocaloric elements, wherein each set comprises at least one mechanocaloric element, and each mechanocaloric element comprises at least one mechanocaloric material. The driving system further comprises a loading system, which is configured to load and unload the first set and the second set of mechanocaloric elements in a plurality of consecutive operational cycles by applying a deformation and / or mechanical load to the at least one mechanocaloric element. The loading system is configured to cyclically load and unload the first and second set of mechanocaloric elements in each operational cycle, such that during a respective loading phase of the first and second set of mechanocaloric elements an at least approximately constant mechanical input power is applied on the mechanocaloric elements, and such that during an unloading phase of the respective first and second set of mechanocaloric elements an at least approximately constant mechanical output power is applied from the mechanocaloric elements on the loading system.

[0016] A mechanocaloric element as used in this disclosure may in some examples be a mechanocaloric regenerator. In some examples, a mechanocaloric element may comprise a mechanocaloric regenerator. A constant power approach, which means in particular providing an approximately constant input power to the mechanocaloric element and receiving a constant output power from the mechanocaloric element, is advantageous. The constant input power may be applied through a constant torque to the loading system. The loading system may comprise drive means, such as e.g. electric motors, which are utilized to load and unload the mechanocaloric elements. These drive means preferably operate with a constant power output and or a constant torque output. It is thus advantageous to have a driving system, which loads the mechanocaloric elements with an approximately constant input power to improve the energy efficiency, reliability and compactness of the driving system. The loading system and the drive means of the loading system can thus be operatedmore efficiently, increasing the overall efficiency, reducing peak power and increasing the compactness of the driving system. The unloading of the mechanocaloric elements preferably feeds a constant power back to the loading system and the driving system to improve the energy efficiency and to reduce peak power. Reducing peak power enables to utilize minimal dimensions, configuration and design, and mass of both the drive means of the loading system as well as any power transmission components such as drive shafts, bearings, shaft couplings, hydraulic elements and tubings etc., as there is no requirement for compensating a higher peak power level during operation.

[0017] In some examples, the loading system has a total operational power, which is the difference between the input power applied on the mechanocaloric elements and the output power applied from the mechanocaloric elements on the loading system, and the total operational power is at least approximately constant over an operational cycle. By keeping the operational power approximately constant over the entire operational cycle, the efficiency may be improved. Further, as the loading system and / or drive means of the loading system may operate with a constant power and / or torque during the entire operational cycle, it is advantageous to load and unload the mechanocaloric elements over the entire cycle with an at least approximately constant total power and / or torque. In some examples, the total operational power may vary around a mean value by at most 100% of the mean value. In some examples, the total operational power may vary around a mean value by at most 75% of the mean value. In some examples, the total operational power may vary around a mean value by at most 50% of the mean value. In some examples, the total operational power may vary around a mean value by at most 30% of the mean value. In some examples, the total operational power may vary around a mean value by at most 25% of the mean value. In some examples, the total operational power may vary around a mean value by at most 20% of the mean value. In some examples, the total operational power may vary around a mean value by at most 10% of the mean value.

[0018] In some examples, in each operational cycle, the first set of mechanocaloric elements is loaded and unloaded phase-shifted with respect to the loading and unloading of the second set of mechanocaloric elements, preferably phase-shifted by 180°.

[0019] By phase-shifting the loading and unloading of the different sets of mechanocaloric elements, the power required by the different sets of mechanocaloric elements during their respective loading phases may be distributed over the operational cycle. Similarly, the power provided by the different sets of mechanocaloric elements during their respective unloading may be distributed over the operational cycle so that the required input power and the receivedoutput power is more evenly distributed over the operational cycle. Preferably, there are at least two sets of mechanocaloric elements and their loading and unloading are phase-shifted by 180°, such that during the operational cycle, one of the two sets of mechanocaloric elements is loaded and requires power while the other set is unloading and feeds power to the loading system. This way, operation of the driving system may be more efficient and more regular.

[0020] In some examples, the loading system is over an operational cycle at least temporarily in contact with each mechanocaloric element, and the loading system is configured to provide the approximately constant mechanical input power by a defined movement of at least a portion of the loading system with respect to the mechanocaloric elements.

[0021] The loading system may not be required to have contact, e.g. mechanical contact to provide the input power, during the whole operational cycle, but only for a portion of the operational cycle. The loading system may comprise movable parts, which are moving with respect to the mechanocaloric elements to load and / or unload the mechanocaloric elements. More precisely, the loading system may comprise movable parts, which are moving with respect to the at least one mechanocaloric material of the mechanocaloric elements, to provide the load and / or deformation on the at least one mechanocaloric material of the mechanocaloric element to load the mechanocaloric material and thus load the respective mechanocaloric element comprising said at least one mechanocaloric material.

[0022] The loading system may comprise at least one loading device. The at least one loading device may be configured to create the defined motion of said at least portion of the loading system with respect to the at least one mechanocaloric material of the at least one mechanocaloric element. With the defined movement, the first constant input power and receive the second constant output power may be provided. The configuration of the at least one loading device, e.g. a cam profile of a cam disc, may be customized to the requirements of the setup, e.g. to create said defined movement of the at least portion of the loading system depending on the at least one mechanocaloric material of the at least one mechanocaloric element and the arrangement of the at least one mechanocaloric elements.

[0023] In some examples, the loading system comprises at least one cam disc having a cam profile. The cam disc rotates during the operational cycle, and the loading system further comprises at least one cam follower for each of the mechanocaloric elements, which are configured to move with respect to the respective mechanocaloric elements. During rotation of the cam disc, the cam profile acts on the cam followers to provide the approximately constantmechanical input power during loading of the respective mechanocaloric elements and to ensure an approximately constant mechanical output power from the respective mechanocaloric elements during unloading.

[0024] The cam followers are configured to move according to the shape of their respective cam disc relative to the position of the mechanocaloric elements to load and / or unload the mechanocaloric elements by applying a deformation and / or mechanical load. More precisely, the cam follower is configured to move with respect to the at least one mechanocaloric material of the mechanocaloric elements, to provide the deformation and / or load on the at least one mechanocaloric material of their respective mechanocaloric element to load the mechanocaloric material and thus load the respective mechanocaloric element comprising said at least one mechanocaloric material.

[0025] The cam discs may be rotated by a drive means, such as e.g. an electric motor. As disclosed above, such an electric motor may provide an improved efficiency for the driving system. The cam followers may move in a reciprocal motion to provide the deformation and / or load on the at least one mechanocaloric materials of the mechanocaloric elements from the rotational motion of the driving system. By shaping the cam profile of the cam disc, the motion of the cam followers may be adjusted. The movement of the cam follower during the operational cycle determines the deformation and / or load provided on the at least one mechanocaloric material of the mechanocaloric elements and thus determines the loading and unloading of the mechanocaloric elements. By selecting a predetermined shape of the cam profile of cam disc, the loading and unloading of the mechanocaloric elements may be adjusted such that an at least approximately constant mechanical input power is applied on the mechanocaloric elements, and an at least approximately constant mechanical output power is received from the mechanocaloric elements. This may improve the efficiency of the driving system.

[0026] In some examples, the cam profile is dependent on the loading and / or unloading material properties of the mechanocaloric material of the mechanocaloric elements such that the loading and / or unloading power is at least approximately constant.

[0027] In some examples, the loading system comprises at least one piston to load and unload the mechanocaloric elements, wherein the loading system is configured to move the piston to provide the approximately constant mechanical input power during loading of the mechanocaloric elements and to ensure an approximately constant mechanical output power from the mechanocaloric elements during unloading.Similarly to the motion of a cam follower of a cam disc, the motion of the piston may be adjusted to provide the approximately constant mechanical input power during loading of the mechanocaloric elements and to ensure an approximately constant mechanical output power from the mechanocaloric elements during unloading. This may improve the efficiency of the driving system.

[0028] In some examples, wherein the mechanocaloric elements comprise barocaloric elements, the loading system comprises a hydraulic pump to load and unload the barocaloric elements.

[0029] The hydraulic pump loads and unloads the barocaloric elements by providing a variable pressure during the operational cycle, i.e. an increasing pressure during loading and a decreasing pressure during unloading. The hydraulic pump may be configured to provide an adjustable pressure during loading and unloading, i.e. the pressure increase and decrease may not be linear. The pressure increase and decrease may be adjusted depending on the mechanical response of the barocaloric materials, e.g. the pressure-volume response characteristics. The pressure increase and decrease may be adjusted, such that the mechanical input power on the barocaloric elements and / or the mechanical output power from the barocaloric elements is at least approximately constant over an operational cycle.

[0030] In some examples, the cam profile is determined by the required movement of the cam follower in dependence of the stress-strain response and / or the pressure-volume response characteristics of the at least one mechanocaloric material of the at least one mechanocaloric elements to obtain the at least approximately constant mechanical input power and the at least approximately constant mechanical output power.

[0031] In some examples, the stress-strain response and / or the pressure-volume response characteristics may be the stress-strain response and / or the pressure-volume response characteristics at the relevant operating conditions. In some examples, the relevant conditions may be the conditions at which the mechanocaloric material operates in the device, such as e.g. temperature span and loading speed. Adjusting the load and / or deformation during loading and unloading based on the stress-strain and / or pressure-volume response characteristic at the conditions at which the mechanocaloric material operates in the device may improve the efficiency of the driving system and the mechanocaloric heating or cooling apparatus. By taking into account the stress-strain and / or pressure-volume response characteristic at the relevant operating parameters, a more constant input and output power may be applied on / received from the mechanocaloric elements.Depending on the material properties, the stress-strain or pressure-volume characteristics of the mechanocaloric material during loading and / or unloading are dependent on the stress, pressure and / or deformation and are usually not linear. Thus, the at least one loading system may be configured to adjust the loading and / or unloading process to provide and / or receive an approximately constant power input and / or output. Determining the cam profile according to the stress-strain response and / or the pressure-volume response characteristics may be utilized to adjust the loading and / or unloading process to compensate the material properties and to provide / receive the approximately constant power input / output. In some examples, the mechanocaloric material may have different stress-strain or pressure-volume characteristics for loading and unloading. The loading system may be configured to adjust the loading and the unloading process differently to enable both an at least approximately constant input power and an at least approximately constant output power. In some examples, the loading device may comprise a cam disc and the cam profile of the cam disc may be shaped differently for the loading and the unloading process of the mechanocaloric elements.

[0032] During the operation of the loading system, several forms of internal energy dissipation arise. The dominant contributions are associated with frictional phenomena, which may manifest either as sliding friction or rolling friction, depending on the local kinematics of the loading system, in particular the interface of the cam followers. One example may be rolling friction for cam followers comprising rollers, which create friction at the rotating cam disc. Additional losses may emerge from hydraulic subsystems as well as from internal material damping and hysteresis in structural components subjected to cyclic loading. Collectively, these mechanisms influence the overall efficiency, torque stability, and operational performance of the system.

[0033] Friction in loading systems, in particular in loading systems comprising cam followers, can occur in at least three principal forms, which are the most dominant contributors to energy dissipation:

[0034] The first principal form of friction is sliding friction, which is dominant when relative tangential motion occurs at the contact interface of the loading system, which is typical for flat cam followers or geometric configurations with nonideal rolling and sliding bearings. The second principal form of friction is rolling friction, for example rolling contact in roller bearings of the loading system, such as rolling contact of the cam followers on the cam disc, etc. Further, as the cam followers may be connected to force amplifiers, which comprise pistons arranged inside cylinders, there is also friction at the seals of the pistons, when the pistons are moved in the cylinders. The third principal form of friction is internal fluid friction, which is dependent on the viscosity of the fluid and the fluid velocity in the fluid lines and the cylinders of theforce amplifiers, the shape of the cross-sections of the fluid lines and the length of the fluid lines, as well as pressure / load and temperature of the fluid. The internal fluid friction may be determined using CFD simulation.

[0035] The instantaneous sliding friction force is described by:

[0036] Fsl - HslF n

[0037] wheres / is the sliding friction coefficient and Fnthe normal force at the interface. The work dissipated during a cycle is:

[0038] Wsi= f Fsids

[0039] Rolling friction is e.g. present when the cam follower incorporates a rolling element (e.g., a roller bearing or a roller), significantly reducing but not eliminating frictional losses due to rolling resistance, internal bearing losses, and micro-slip.

[0040] Rolling friction (or rolling resistance) is typically much smaller than sliding friction and arises from deformation losses in the roller, cam surface, and bearing elements. The rolling resistance force may be expressed as:

[0041] Frail ~ FnCr I Troll

[0042] The rolling resistance force may be expressed as:

[0043] f roll ~ FnCr

[0044] where Cris the rolling resistance coefficient and rro / / the effective rolling radius. The corresponding energy dissipation per cycle is:

[0045] Wroll—f Frollds — f Mrooldd

[0046] Friction forces become significant when high normal loads are present.

[0047] Mechanocaloric elements introduce a highly nonlinear dynamic loading profile characterized by stress-induced phase transformation, pronounced hysteresis, and rate-dependent mechanical response. These effects produce rapid temporal variations in normal force Fn(t) which directly affect both sliding and rolling friction forces. Because Fn(t) can exhibit sharp peaks, both sliding and rolling friction losses become strongly time-dependent.

[0048] The driving torque of the loading system, in particular a drive means driving the loading system, e.g. a drive means rotating the cam disc, must overcome not only the load imposed by the mechanocaloric element but also the frictional resistance and other losses.Even when the cam profile is designed using a constant power / torque approach taking into account the material characteristics, such as the stress-strain response and / or the pressurevolume response characteristics, the presence of friction-induced force components introduces deviations from the ideal torque profile. In combination with mechanocaloric element hysteresis, these effects may significantly influence torque ripple, efficiency, and mechanical stability if they are not considered in the construction of the cam disc shape in the constant-power approach.

[0049] Accurate evaluation of sliding and rolling friction may be conducted using a multilevel methodology:

[0050] Analytical models allow closed-form estimation of sliding friction, rolling resistance, internal fluid friction and cycle-integrated energy dissipation based on measured force-displacement relations.

[0051] Numerical simulations (finite-element analysis and multibody dynamics) enable the incorporation of linear and nonlinear material laws, advanced friction models (Coulomb, Stribeck, rolling resistance models), and time-varying normal forces.

[0052] Experimental characterization through torque transducers, rotary encoder, high-resolution displacement / force measurements, and comparative work-input / output analyses provides empirical validation.

[0053] The combination of these approaches ensures that frictional losses (sliding and rolling and internal fluid friction) are properly captured within the model of the loading system, in particular the model for creating the cam profile of the cam disc.

[0054] Given the significant impact of sliding and rolling friction and internal fluid friction on system performance, these effects may be incorporated into the design and optimization of the loading system, in particular the design and optimization of the cam profile s(cp) of the cam disc. Neglecting friction may lead to inaccurate torque predictions, suboptimal efficiency, increased wear, and potentially unstable operation.

[0055] Therefore, the loading system, in particular the cam profile s(cp), may preferably be developed from a comprehensive model that integrates:

[0056] • dynamic normal force evolution,

[0057] • sliding and rolling friction contributions,

[0058] • internal fluid friction

[0059] • material properties of the mechanocaloric material, in particular stress-strain response or pressure-volume response, andmechanocaloric element hysteresis.

[0060] Preferably, the most dominant forms of energy dissipation (not only frictional but also hysteresis, hydraulic, structural, or otherwise) are anticipated and incorporated in this approach and are taken into account for the determination of the properties of the loading system, in particular the cam profile of the cam disc. Thus, the design of the loading system, in particular the cam profile s(cp) of the cam disc, is determined to ensure an approximately constant power / torque response throughout the operational cycle. Driving the driving system according to this preferred example with a constant torque on the loading system, in particular on the cam shaft and / or cam disc, facilitates driving the loading system, in particular cam shaft and / or cam disc, by drive means and minimizes torque ripple, minimises system size, reduces wear, and improves overall efficiency, which is for example illustrated in Fig. 8. To determine the design of the loading system, in particular the cam profile s(cp) of the cam disc, at least the most dominant forms of energy dissipation may be taken into account, which are described in detail above.

[0061] The shape of the cam disc and thus the cam profile may be according to the constant power approach as disclosed herein, preferably according to the constant power approach taking into account internal energy dissipation losses. In other words, the cam profile may correspond to the calculation of an ideal cam profile, e.g. as disclosed in this disclosure. The ideal cam profile may be calculated to load the mechanocaloric elements with a constant mechanical input power and to unload the mechanocaloric elements with a constant mechanical output power.

[0062] In some examples, the design of the loading system, in particular the cam profile s(cp) of the cam discs, is determined based on the required movement of the loading system, in particular the cam followers in dependence of the most dominant forms of energy dissipation in particular dynamic normal force evolution, sliding and rolling friction contributions, internal fluid friction, material properties of the mechanocaloric material, in particular stress-strain response or pressure-volume response, and mechanocaloric element hysteresis, to obtain the approximately constant mechanical input power on the mechanocaloric elements and / or cam shaft during loading phase and an approximately constant mechanical output power from the mechanocaloric elements and / or cam shaft during unloading phase.

[0063] In some examples, the mechanocaloric elements comprise barocaloric elements and the loading system comprises a hydraulic pump, and in these examples, the controller may control the pressure that the hydraulic pump exerts on the barocaloric elements.In some examples, the loading system may comprise a controller, which is configured to actuate the loading system in a way that the loading system loads and / or unloads the at least two mechanocaloric elements in a way, that the at least approximately constant input and / or output power is obtained.

[0064] Preferably, the controller utilizes the calculated, ideal deformation of the mechanocaloric elements as a control function and optimizes the actuation of the loading system during loading and / or unloading to obtain the at least approximately constant input and / or output power. In some examples, the loading system may comprise a cam disc and the cam disc may be subject to production tolerances and may not be forged in the ideally, theoretically calculated way. In some examples, irrespective of the type of loading system, the loading system may for any reasons not be able to produce the ideally, theoretically calculated loading and unloading process to the mechanocaloric elements. Similarly, during operation, the material of the regenerator may not behave ideally or for another reason, there may be a deviation from the ideal, theoretical setup. The loading system may comprise a controller, which may control the movement and / or actuation of the loading system. In other words, the controller may control the loading and unloading of the mechanocaloric elements by the loading system, e.g. the rotation of a cam disc or the pressure on the barocaloric elements by a hydraulic pump. The controller may control the movement or actuation of the loading system or may control the loading and unloading, in a way that the movement or actuation of the loading system is optimized on loading and unloading the mechanocaloric elements with constant mechanical input and output power. The controller may receive information on the actual input and output power of the mechanocaloric elements to control the movement and / or actuation of the loading system. The controller may comprise a control circuit, e.g. a PID controller or another type of controller, to optimize the movement or actuation of the loading system to load and unload the mechanocaloric elements with constant power. For example, the controller may realize during loading that the input power on a barocaloric element is too high and may then reduce the pressure on the barocaloric element to reduce the input power. The controller may monitor the input and output power of the mechanocaloric elements during the operational cycle. The controller may optimize the movement and / or actuation of the loading system during the operational cycle on an at least approximately constant mechanical input power on the mechanocaloric elements and an at least approximately constant mechanical output power from the mechanocaloric elements.

[0065] In some examples, over an operational cycle, the loading system is configured to provide a predefined, in particular variable, load on and / or to cause a predefined, in particular variable, deformation of the mechanocaloric element. By providing a predefined load during loadingand unloading, i.e. over the operational cycle, the input power and output power may be adjusted. By providing a variably, predefined load over the operational cycle, the input power and output power may be adjusted to be at least approximately constant. Similarly, by providing a predefined deformation during loading and unloading, i.e. over the operational cycle, the input power and output power may be adjusted. By providing a variably, predefined deformation over the operational cycle, the input power and output power may be adjusted to be at least approximately constant. Operating the driving system with an at least approximately constant input and output power may improve the efficiency.

[0066] In some examples, the load and / or the deformation is determined, in particular as a function over time, in dependence on characteristics of the at least one mechanocaloric material of the respective mechanocaloric element. The characteristics of the mechanocaloric material of the respective mechanocaloric element determine the power in dependence of the load and / or deformation. Thus, an energy efficient operation, which uses a constant power approach, may be achieved by adjusting the load and / or deformation in dependence of the characteristics of the at least one mechanocaloric material of the mechanocaloric elements.

[0067] In some examples, each operational cycle includes holding phases between the loading and unloading phases of the respective sets of mechanocaloric elements, wherein, preferably, the loading system is configured to provide at least approximately a constant load on and / or constant deformation on the at least one mechanocaloric material of the at least one mechanocaloric element during each holding phase. During the operational cycle, more precisely after loading and unloading, heat needs to be transferred to or away from the mechanocaloric elements, e.g. by a heat transfer fluid, which is transferring heat with the mechanocaloric elements via a heat exchanger. In some examples, there may be no holding phase in between the loading and unloading phases of the respective sets of mechanocaloric elements, and the heat transfer may be taking place at the end or beginning of the loading and unloading phases when the mechanocaloric elements are still subject to a change of deformation.

[0068] In some examples, there may be holding phases in between the loading and unloading phases of the respective sets of mechanocaloric elements, and the heat transfer may take place during the end or beginning of loading and / or unloading phases, and, optionally, during the holding phases. In some examples, there may be holding phases between consecutive loading and unloading phases, but not between consecutive unloading and loading phases. In some examples, there may be holding phases between consecutive unloading and loading phases, but not between consecutive loading and unloading phases.In some examples, the heat transfer takes place during a holding phase, which is a phase, wherein the mechanocaloric material of the mechanocaloric elements is not further loaded or unloaded, i.e. the load (force and / or hydrostatic pressure) force acting on the mechanocaloric material and / or its deformation (shape and / or volume change) is at least approximately constant. In some examples, the holding phases each may cover up to 50% of the operational cycle.

[0069] In some examples, the holding phase is longer or shorter than a loading phase or an unloading phase.

[0070] In some examples, the loading phase and the unloading phase cover the same amount of an operational cycle.

[0071] In some examples, the driving system comprises four sets of mechanocaloric elements, which are loaded and unloaded with a phase-shift of 90° and each of the loading phase, unloading phase and the two holding phases covers 25% of an operational cycle. That way, during the entire operational cycle, one of the sets of mechanocaloric elements is in its loading phase, another one is in its unloading phase and the remaining two sets of mechanocaloric elements are in one of their holding phases, respectively. Thus, at all times during operation, one of the mechanocaloric elements is in its loading phase and another one is in its unloading phase. In combination with the loading system, which cyclically loads and unloads each mechanocaloric element with a constant mechanical input and output power, this leads to an approximately constant power input and power output of the whole driving system.

[0072] In some examples, the loading system is configured to couple the first set and the second set of mechanocaloric elements such that the unloading phase of one set of mechanocaloric elements contributes energetically to the loading phase of the other set of mechanocaloric elements. Thereby, the energy and / or torque produced by one set of mechanocaloric elements during unloading may be used to drive the loading of another set of mechanocaloric elements. This way, the energy and or torque production during the unloading of one set of mechanocaloric elements will be combined with the energy and / or torque consumption of the other set of mechanocaloric elements during loading. Thus, the overall energy level of the driving system will be more evenly distributed over the operational cycle. In combination with the loading system, which cyclically loads and unloads each mechanocaloric element with a constant mechanical input and output power, the overallpower input and output of the driving system is more constant, preferably at least approximately constant.

[0073] In some examples, the arrangement comprises a number of sets of mechanocaloric elements, wherein the loading and unloading phases of the respective sets of mechanocaloric elements are shifted by 360 degrees divided by the number of sets of mechanocaloric elements.

[0074] By arranging the operational cycles of the various mechanocaloric elements shifted by a predetermined phase shift equalling to 360 degrees divided by the number of sets of mechanocaloric elements, the loading and unloading phases of the mechanocaloric elements are spread equally over the whole operational cycle, which enables to provide / receive an approximately constant input / output power during the entire operational cycle.

[0075] In some examples, the loading system comprises force amplifiers, wherein each of the force amplifiers is arranged at one of the individual mechanocaloric elements. Preferably, the loading system comprises one force amplifier for each mechanocaloric element, wherein one force amplifier is arranged at each individual mechanocaloric element.

[0076] The force amplifiers are arranged between the cam followers and the mechanocaloric elements and are configured to transfer energy and power therebetween.

[0077] In some examples, the driving system comprises an arrangement of at least one mechanocaloric elements, and the loading system comprises at least one cam disc having a cam profile. The cam disc rotates during the operational cycle, and the loading system further comprises at least one cam follower and at least one force amplifier for each cam follower. The force amplifiers are arranged between the at least one cam follower and the at least one mechanocaloric element and are configured to transfer energy and power therebetween. The force amplifiers are amplifying the power and energy from the motion of the cam followers and are configured to exert the amplified power and energy on the mechanocaloric elements to load and unload the mechanocaloric elements. During rotation of the cam disc, the cam profile acts on the cam followers to provide the approximately constant mechanical input power during loading of the respective mechanocaloric elements and to ensure an approximately constant mechanical output power from the respective mechanocaloric elements during unloading. In some examples, the driving system comprises an arrangement of multiple mechanocaloric elements. In some examples, the driving systemmay be a driving system according to any paragraph of this disclosure, especially according to any of the claims.

[0078] In some examples, one cam follower may be connected to multiple force amplifiers and may provide power and energy to all of them. Each of the force amplifiers may be connected to another mechanocaloric element, such that there is one force amplifier for each mechanocaloric element and all the mechanocaloric elements are loaded by the same cam follower and their respective force amplifier.

[0079] In some examples, the driving system comprises multiple mechanocaloric elements and some of the mechanocaloric elements are loaded and unloaded by at least one cam follower in combination with force amplifiers for these mechanocaloric elements, and in some examples the other mechanocaloric elements are directly loaded and unloaded via the cam followers without a force amplifier being arranged therebetween.

[0080] In some examples, the loading system may comprise force amplifiers, and may not comprise cam discs and cam followers, but other means to load and unload the mechanocaloric elements. Generally speaking, the force amplifiers may be arranged between the means to load and unload the mechanocaloric elements and the mechanocaloric elements to transfer energy and power therebetween and to amplify the force acting on the mechanocaloric elements.

[0081] The force amplifiers reduce the force on the side of the cam follower (generally speaking, on the side of the means for loading and unloading the mechanocaloric elements), but the displacement is higher at that side. This is advantageous, as the larger displacement at the side of the cam follower allows for a larger error tolerance of the cam profile or means for loading and unloading. The deviation from the ideal loading and unloading of the mechanocaloric elements due to a deviation of the cam profile of the cam discs from the ideal cam profile of the cam discs has less negative effects when the force amplifiers are used. Further, the force amplifiers reduce the force that the power transmission components, such as e.g. drive shafts, bearings, shaft couplings, hydraulic elements and tubings etc., are operating on. This reduces the friction losses and enables to utilize minimal dimensions, configuration and design, and mass of the power transmission components such as drive shafts, bearings, shaft couplings, hydraulic elements and tubings etc., as there is no requirement for withstanding a higher force during operation. As the power transmission components may be made smaller, the loading system and / or the driving system may be built smaller and / or lighter, which facilitates production and transport.In some examples, the force amplifiers are hydraulic, pneumatic, mechanical, electric or of another type of force amplifiers.

[0082] The force amplifiers reduce the force to / from the cam discs, cam followers, shaft and bearings during operation. With reduced force, there is less friction and less mechanical loss, which improves the efficiency of the driving system and the mechanocaloric heating or cooling apparatus.

[0083] The loading system may comprise force amplifiers irrespective of whether the mechanocaloric elements comprise barocaloric elements or elastocaloric elements or a combination of both. The loading system may comprise force amplifiers when the mechanocaloric elements comprise barocaloric elements. The loading system may comprise force amplifiers when the mechanocaloric elements comprise elastocaloric elements.

[0084] The force amplifiers may have an elongation, e.g. a hydraulic force amplifier may comprise a tubing between a piston on the first side and a piston on the second side to transfer energy and power between the two sides. The tubing may be elongated to enable to arrange the first side and the second side spaced apart. This way, piston at the first end of the force amplifier may be arranged at the cam follower and the second end of the force amplifier may be arranged at a distal position. At said distal position, there may be an arrangement of multiple mechanocaloric elements. This way, the mechanocaloric elements may be arranged close to one another, which may facilitate transport, installation and maintenance, and may result in a more compact design. This setup may also facilitate transport, installation and maintenance of the cam discs, cam followers and drive shaft as it is easier to access these parts without the mechanocaloric elements being arranged around them.

[0085] BRIEF DESCRIPTION OF THE DRAWINGS

[0086] These and other characteristics will become clear from the following description of illustrative embodiments, given as non-restrictive examples, with reference to the attached drawings, in which:

[0087] Figure 1 illustrates an example of a driving system for driving a mechanocaloric heating or cooling apparatus.

[0088] Figure 2 illustrates an example of material properties of a mechanocaloric (in this case elastocaloric) material.Figure 3a illustrates the torque of mechanocaloric driving system, when loaded and unloaded with a linear displacement loading and unloading function at different number of mechanocaloric elements.

[0089] Figure 3b illustrates a linear displacement loading and unloading function.

[0090] Figure 4a illustrates an example of an operational cycle (i.e. deformation changes over time) of a single mechanocaloric element obtained based on the material response of the corresponding mechanocaloric material.

[0091] Figure 4b illustrates an example of an operational cycle (i.e. deformation changes over time) of an arrangement of four mechanocaloric elements obtained based on the material response of the corresponding mechanocaloric material.

[0092] Figure 5a illustrates the torque of a driving system, when loaded and unloaded with a loading and unloading function based on the material response of the mechanocaloric material.

[0093] Figure 5b illustrates the power of a driving system, when loaded and unloaded with a loading and unloading function which ensures a constant power approach based on the material response of the mechanocaloric material.

[0094] Figure 6a illustrates experimental data of the produced torque of an exemplary arrangement of one, two and four mechanocaloric elements.

[0095] Figure 6b illustrates experimental data of the load and displacement for each of the four mechanocaloric elements and torque of an exemplary arrangement of four mechanocaloric elements.

[0096] Figure 7 illustrates an example of a driving system for driving a mechanocaloric heating or cooling apparatus comprising force amplifiers.

[0097] DETAILED DESCRIPTION

[0098] This disclosure provides a driving system for a mechanocaloric heating or cooling apparatus, which provides an improved loading system for mechanocaloric elements or mechanocaloric regenerators, the loading system providing a constant total operational power during operation.

[0099] Figure 1 illustrates an example of a driving system 100, which is configured to drive a mechanocaloric heating or cooling apparatus. The driving system 100 comprises an arrangement with at least two sets of mechanocaloric elements 120, each set may comprise one or more mechanocaloric elements 120. A mechanocaloric element 120 as used in this disclosure may in some examples be a mechanocaloric regenerator. In some examples, a mechanocaloric element 120 may comprise a mechanocaloric regenerator. In the example illustrated in Figure 1 , the arrangement comprises four sets of mechanocaloric elements120a-d. In other examples, another number of mechanocaloric elements 120 or another number of sets of mechanocaloric elements 120 may be comprised by the arrangement. However, the arrangement may comprise other types of mechanocaloric elements 120. In some examples, the arrangement may comprise mechanocaloric elements 120 of different types. The at least one mechanocaloric element 120 comprises at least one mechanocaloric material. In some examples, the mechanocaloric element 120 may comprise a single mechanocaloric material. In some examples, different mechanocaloric elements 120 may comprises different, for example multi-layered mechanocaloric materials.

[0100] The driving system 100 comprises at least one loading system 140. The loading system 140 is configured for mechanical power supply and power transmission. The loading system 140 is configured to load and unload the at least one mechanocaloric element 120 in a plurality of consecutive operational cycles by applying a deformation (shape and / or volume change) to the at least one mechanocaloric material of the at least one mechanocaloric element 120. The loading system 140 loads and unloads the at least one mechanocaloric element 120 in operational cycles, the operational cycle comprising at least a loading phase, wherein the loading system 140 loads the at least one mechanocaloric element 120 by applying a deformation to the at least one mechanocaloric material of the at least one mechanocaloric element 120, and an unloading phase, wherein the loading system 140 unloads the at least one mechanocaloric element 120 by removing a deformation (shape and / or volume change) from the at least one mechanocaloric material of the at least one mechanocaloric element 120. Depending on the mechanocaloric material that the at least one mechanocaloric element 120 comprises, the loading phase of the operational cycle may, e.g. for a mechanocaloric material, comprise applying a mechanical stress, pressure and / or force to the mechanocaloric material by the loading system 140 so that the mechanocaloric material undergoes a stress or pressure-induced reversible transition. Correspondingly, for a mechanocaloric material, the unloading phase of the operation cycle may comprise reducing the mechanical stress, pressure and / or force to the mechanical material by the loading system 140 so that the mechanocaloric material reverts to its original state.

[0101] The driving system 100 comprises a frame 110, in which the at least two mechanocaloric elements 120 (at least one mechanocaloric element 120 for each of the at least two sets of mechanocaloric elements 120) and the loading system 140 are arranged. In the example illustrated in Figure 1, the arrangement comprises four sets of mechanocaloric elements 120a-d and a loading system 140. In some examples, there may be another number of mechanocaloric elements 120 per set, e.g. one, three, four, five or another number. In someexamples, the different sets of mechanocaloric elements may have different numbers of mechanocaloric elements 120.

[0102] Preferably, the mechanocaloric elements 120a-d of the different sets of mechanocaloric elements are loaded and unloaded out of phase with respect to each other, in particular phase-shifted by 360 degrees divided by the number of sets. In this example, the mechanocaloric elements 120a-d are loaded and unloaded phase-shifted by 90° as there are four sets of mechanocaloric elements 120a-d. Because of this, the energy / work released during the unloading phase of one of the mechanocaloric elements 120a-d may contribute to the work and / or energy required for loading the other mechanocaloric elements 120a-d. In other words, the energy returned from one of the mechanocaloric elements 120a-d can be fed back into the driving system 100 during the unloading cycle and the energy may be used for loading in the next cycle or the loading of another mechanocaloric element 120, e.g. another mechanocaloric element 120, which is in its loading phase and thus requires energy and / or force and / or torque and / or pressure and / or deformation for loading.

[0103] As an example, the mechanocaloric elements 120a, 120b are forming a pair in Figure 1. The mechanocaloric elements 120a, b are loaded and unloaded by the loading system 140 in operational cycles and are preferably out of phase by 180 degrees, that is that during the unloading phase of mechanocaloric element 120a, the mechanocaloric element 120b is in its loading phase. The force / energy returned by unloading of the mechanocaloric element 120a during its unloading phase is utilized by the loading system 140 to contribute energetically the loading in the loading phase of mechanocaloric element 120b. Thus, the loading system 140 couples the pair of mechanocaloric elements 120 such that the unloading phase of one mechanocaloric element 120 of the pair of mechanocaloric elements 120 contributes energetically to the loading phase of the other mechanocaloric element 120 of the pair of mechanocaloric elements 120. In other words, the loading system 140 is configured for a transfer of mechanical energy from the mechanocaloric elements 120 to one another. Thus the energy being provided during the unloading phase of one mechanocaloric element 120 may be transferred to another mechanocaloric element 120, which is preferably currently in its loading phase.

[0104] The person skilled in the art will understand, that any even number of sets of mechanocaloric elements 120 may preferably be arranged in such pairs, e.g. two, four, six, eight, etc.

[0105] In another example, there may be any number of sets of mechanocaloric elements and the loading and unloading phases are respectively phase-shifted by 360° degrees divided by thenumber of sets. This way, the loading and unloading phases of the different mechanocaloric elements are distributed evenly along the operational cycle. In combination with the loading system, which cyclically loads and unloads each mechanocaloric element with a constant mechanical input and output power, the overall energy consumption for loading and the energy production during unloading is at least approximately constant.

[0106] The loading system 140 may comprise at least one loading device. In some examples, the loading device may be a cam, such as a cam disc 145,146, or a piston. In some examples, the piston may be mechanically, electromagnetically, pneumatically or hydraulically controlled. The at least two mechanocaloric elements 120 may be arranged around the at least one loading device in at least one layer, wherein each layer comprises at least one mechanocaloric element 120. In the example illustrated in Figure 1, the four mechanocaloric elements 120a-d comprise a mechanocaloric material and the loading system 140 comprises two cam discs 145,146 to load and unload the four mechanocaloric elements 120a-d in an operational cycle. In the example illustrated in Figure 1, two of the four mechanocaloric elements 120a,b are arranged in a first layer around cam disc 146 and the other two mechanocaloric elements 120c, d are arranged in a second layer around cam disc 145.

[0107] Though only numbered for mechanocaloric elements 120c, the loading system 140 comprises a cam follower comprising a wheel 127c and a piston 122c to transmit mechanical energy. The person skilled in the art will understand, that the loading system 140 comprises corresponding cam followers with wheels and pistons for the other mechanocaloric elements 120a, b,d as well. The cam followers are over an operational cycle at least temporarily in mechanical contact with the mechanocaloric element 120, i.e. during the loading phase when the cam followers are providing a load (e.g. force and / or hydrostatic pressure) to the mechanocaloric material of the mechanocaloric elements 120a-d and are thereby loading the mechanocaloric material. The cam discs 145,146 are configured to actuate the cam followers to create a reciprocating, linear motion in the cam followers. The cam followers are applying a load (e.g. force and / or hydrostatic pressure) to the mechanocaloric material of the mechanocaloric elements 120a-d during their reciprocating motion. The cam followers are articulated by the cam profile, i.e. the shape of the cam disc 145,146, and thus are subject to a defined movement with respect to the at least one mechanocaloric material 120. That being said, the cam followers are applying a load (e.g. force and / or hydrostatic pressure) to the mechanocaloric material of the mechanocaloric elements 120a-d, which is dependent on the cam profile as the reciprocating motion of the cam followers is dependent on the shape of the cam discs 145,146. The loading system 140 is thus configured to provide over an operational cycle, in particular by a defined movement of at least a portion of the loading system 140 with respect to the at least one mechanocaloric material of the at least onemechanocaloric element 120, a predefined, in particular variable, load on and / or to cause a predefined, in particular variable, deformation of the at least one mechanocaloric material of the at least one mechanocaloric element 120.

[0108] By selecting a predefined cam profile, the movement of the cam followers may be adjusted and / or selected. Preferably, the cam profile equalling the movement of the cam followers is selected in a way that during a loading phase of the operational cycle a first at least approximately constant mechanical input power is applied on the mechanocaloric material of the mechanocaloric element 120 by the cam follower and such that during an unloading phase of the operational cycle a second at least approximately constant mechanical output power is applied from the mechanocaloric material of the mechanocaloric element on the cam follower and towards the loading system 140. This will be described in more detail with reference to Figure 2. During unloading of the mechanocaloric element 120, or more precisely, the at least one mechanocaloric material of the at least one mechanocaloric element 120, there loading system 140 is providing a force on the mechanocaloric material in a way that the unloading of the mechanocaloric material is not abrupt, but at a predefined speed, so that the work and / or energy and / or output power provided during unloading is at least approximately constant.

[0109] In the example of Figure 1, the cam discs 145,146 are having the same cam profile so that each of the mechanocaloric elements 120a-d is having the same loading phase (only phase shifted) and is receiving the constant mechanical input power during the loading phase. Consequently, each of the mechanocaloric elements 120a-d has the same unloading phase (only phase shifted) and thus provides the constant mechanical output power during the unloading phase. Typically, mechanocaloric materials are following a hysteresis when they are loaded and unloaded. Additionally, the driving system 100 is subject to friction losses, thus the constant mechanical output power is always lower than the constant input power. In the example of Figure 1, the cam discs 145,146 are connected by a drive shaft 141, which provides power from a drive means, e.g. an electric motor or another type of motor or drive means, to provide rotation of the cam discs 145,146. Generally speaking, the loading system 140 may comprise a drive means (which is not shown in Figure 1) and a drive shaft 141 or another means to connect various parts of the loading system 140 to enable energy transfer between different parts of the loading system 140, e.g. the cam discs 145,146 as in the example of Figure 1. In this example, the cam discs 145,146 are arranged at a rotational offset of 90 degrees to one another at the same drive shaft 141. With this arrangement, the two mechanocaloric elements 120a, b are opposite in phase with their loading and unloading phases, i.e. the loading phase of the mechanocaloric elements 120a corresponds to theunloading phase of the mechanocaloric element 120b and vice versa. As will be described in further detail below and as is illustrated in Figure 5b, the two mechanocaloric elements 120c,d are also opposite in phase with loading and unloading and due to the 90 degree phase offset of the cam discs 145,146 to one another, the loading and unloading of the mechanocaloric elements 120c,d is phase-offset to the loading and unloading of the mechanocaloric elements 120a, b. As will be more clear from Figure 5b, thereby, the four mechanocaloric elements 120a-d are having their respective loading and unloading phases at a phase offset of 90 degrees to one another. In combination with the loading system, which cyclically loads each mechanocaloric element 120a-d with the same constant mechanical input power and unloads it with the same constant mechanical output power, the driving system 100 has an at least approximately constant power input and output throughout the whole operational cycle, as at every time during the operational cycle, one of the four mechanocaloric elements 120a-d is in its loading phase and another one of the four mechanocaloric elements 120a-d is in its unloading phase.

[0110] In some examples, the arrangement of the mechanocaloric elements 120 as shown in Figure 1 may be extended to the bottom and the top by adding more mechanocaloric elements 120 in pairs, each being driven (loaded and unloaded) by the loading systems 140, e.g. by another cam disc 145,146 arranged on the drive shaft 141. Preferably, the total number of mechanocaloric elements 120 is a multiple of two starting at four as this facilitates lining up of the loading phases and unloading phases of the mechanocaloric elements 120 in a way there is always the same number of mechanocaloric elements 120 in their respective loading phase and in their respective unloading phase. In combination with the loading system, which cyclically loads each mechanocaloric element 120 with the same constant mechanical input power and unloads it with the same constant mechanical output power an at least approximately constant input power to / output power from the driving system 100 is provided.

[0111] In some examples, there may be another number of mechanocaloric elements arranged.

[0112] In some examples, a single cam disc 145,146 may drive more than two mechanocaloric elements 120a-d. In some examples, each cam disc 145,146 may be configured to drive four mechanocaloric elements. The four mechanocaloric elements 120a-d may for example be arranged around the cam disc 145 in a single layer in 90-degree intervals, similar to the shape of a cloverleaf. As will be described in more detail below, the four mechanocaloric elements 120a-d are preferably driven in a way that the mechanocaloric elements 120a-d are having a phase offset of 90 degrees with respect to one another’s operational cycle. In an arrangement of four mechanocaloric elements 120 at one cam disc 145,146, the cam discmay provide one operational cycle for each of the mechanocaloric elements 120 for each revolution of the cam disc 145,146. In some examples, eight mechanocaloric elements 120 may arranged in a single layer around a single cam disc 145,146 and may be driven by said single cam disc 145,146. The cam disc 145,146 may then comprise a cam profile, which is configured to drive two operational cycles of each mechanocaloric element 120 for each revolution of the cam disc 145,146. The cam disc 145,146 may e.g. comprise a symmetrical cam profile such that mechanocaloric elements 120 being arranged at opposing sides of the cam disc 145,146 are operated correspondingly, i.e. these mechanocaloric elements are in their respective loading phases at the same time interval, the same being true for their unloading phases and possible holding phases.

[0113] In the example illustrated in Figure 1, the cam disc 145,146 are arranged in the middle and the mechanocaloric elements 120 are arranged facing outwards. In some examples, the at least one mechanocaloric element 120 may be mounted at a central support and the at least one cam disc 145,146 may be a rotating cam disc or a rotating cam ring, which is encompassing the at least one mechanocaloric element 120 to provide the power and / or force and / or torque on the at least one mechanocaloric element 120 for the loading and / or unloading phase from the outside, e.g. by pressing the at least one mechanocaloric element 120 onto the central support.

[0114] In some examples, the at least one mechanocaloric element may be mounted parallelly to the axis of rotation of the at least one cam disc 145,146. The at least one cam disc may then comprise a cam profile, which is not on the radial surface of the cam disc, but which is on any of the face sides of the cam disc, sometimes this also being referred to as a face cam. The cam then drives motion in the direction parallel to the rotational axis of the at least one cam. This enables a compact design as multiple mechanocaloric elements 120 may be stacked below and above a cam disc and may be driven by said cam.

[0115] The drive shaft may be driven by drive means. The drive means may in some examples be an electric drive. In some examples, there may be no cam, but a pneumatic drive or a hydraulic drive for loading and unloading the mechanocaloric elements. There may be an internal accumulator of a fluid, e.g. air or oil, which stores a part of the released energy during unloading and utilizes it for loading the next mechanocaloric element. In some examples, there may be an electric generator, which converts mechanical energy created by a mechanocaloric element during unloading into electrical energy to pass the energy to another drive means, which is loading the next mechanocaloric element.In some examples, loading system 140 may be configured to provide a predefined, in particular variable, load and / or to cause a predefined, in particular variable, deformation of the mechanocaloric material of the mechanocaloric element 120 during the loading phase. Referring to the example of Figure 1, the cam discs 145,146 may have a predetermined cam profile or predetermined shape to cause a predefined movement of the cam followers and thus provide a predefined load (e.g. force and / or hydrostatic pressure) to the mechanocaloric material und thus provide said predefined load and / or cause said predefined deformation of the mechanocaloric material.

[0116] Similarly, during the unloading phase, the cam profile may cause a predefined movement of the cam followers and thus cause a predefined profile of reducing the load (e.g. force and / or hydrostatic pressure) provided to the mechanocaloric material.

[0117] Thereby, the loading system 140 is, over an operational cycle, configured to provide a predefined, in particular variable, load on and / or to cause a predefined, in particular variable, deformation of the mechanocaloric material of the mechanocaloric element 120. Thereby, during the loading phase, the at least approximately constant mechanical input power may be applied on the mechanocaloric material of the mechanocaloric element 120, and during the unloading phase, the at least approximately constant mechanical output power may be applied from the mechanocaloric material of the mechanocaloric element to the loading system 140. In some examples, the at least approximately constant mechanical input power may deviate around a mean mechanical input power by up to 100% of the mean value. In some examples, the at least approximately constant mechanical input power may deviate around a mean mechanical input power by up to 50% of the mean value. In some examples, the at least approximately constant mechanical input power may deviate around a mean mechanical input power by up to 30% of the mean value. In some examples, the at least approximately constant mechanical input power may deviate around a mean mechanical input power by up to 20% of the mean value. In some examples, the at least approximately constant mechanical input power may deviate around a mean mechanical input power by up to 10% of the mean value. In some examples, the at least approximately constant mechanical output power may deviate around a mean mechanical output power by up to 100% of the mean value. In some examples, the at least approximately constant mechanical output power may deviate around a mean mechanical output power by up to 50% of the mean value. In some examples, the at least approximately constant mechanical output power may deviate around a mean mechanical output power by up to 30% of the mean value. In some examples, the at least approximately constant mechanical output power may deviate around a mean mechanical output power by up to 20% of the mean value. In someexamples, the at least approximately constant mechanical output power may deviate around a mean mechanical output power by up to 10% of the mean value.

[0118] The power P provided to the mechanocaloric material by inducing a deformation during the loading phase, e.g. by a force or a mechanical stress or pressure, is equal to the derivative of the work W with respect to time t, being equal to the torque T applied from the loading system being multiplied by the angular rotational speed a).

[0119] „ dW „ .

[0120] P = — dt = T x a) = const.

[0121] The same holds true for the power provided from the mechanocaloric material to the loading system 140 and hence the driving system 100 during the unloading phase. Preferably, the power provided to and from the mechanocaloric material is constant over time t. The loading system may comprise drive means, such as e.g. electric motors, which are utilized to load and unload the mechanocaloric elements. These drive means normally operate with a constant power output and / or a constant torque output. It is thus advantageous to have a driving system, which improves the loading of the mechanocaloric elements by loading the mechanocaloric elements with an approximately constant input power to improve the energy efficiency of the driving system. The loading system and the drive means of the loading system can thus be operated more efficiently, increasing the overall efficiency of the driving system. The unloading of the mechanocaloric elements preferably feeds a constant power back to the loading system and the driving system to improve the energy efficiency and to reduce peak power. Reducing peak power enables to utilize minimal dimensions, configuration and design, and mass of both the drive means of the loading system as well as any power transmission components such as drive shafts, bearings, shaft couplings, hydraulic elements and tubings etc., as there is no requirement for compensating a higher peak power level during operation.

[0122] The incremental change in work dW, as a function of force F and displacement ds, is classically written as:

[0123] dW = F(s) ds

[0124] To emphasize that the work input / output per unit time (i.e. , power) remains constant, specifically state should be written as:

[0125] dW

[0126] — — = const,

[0127] dt

[0128] Since dW = F(s) ds this could be written in terms of time t namely:1

[0129] dW ds

[0130] — — = F(s) — = const,

[0131] dt dt

[0132] If the force F(s) increases, the velocity ds / dt must decrease accordingly so that the product (s) ds / dt remains unchanged at the constant value. Conversely, if the force decreases, the velocity should increase such that the power remains the same. In practice, the system (shape of cam disc) adjusts the cam follower speed so that the input power remains constant.

[0133] The force F(s) is a material characteristic of the mechanocaloric material, which is also dependent on the displacement ds, the deformation speed is ds / dt. In the example of Figure 1, the deformation speed is the speed at which the cam followers 147 are moving in their linear motion as they are actuated by the cam disc 146. The force provided to / from the mechanocaloric elements 120, and hence the movement of the cam followers 147, defines the power provided to or from the mechanocaloric elements 120.

[0134] Therefore, the cam profile is in the example of Figure 1 relevant to adjust the movement speed of the cam followers 147, equalling the deformation speed. The cam profile is thus defining the power transmission to the mechanocaloric elements 120a-d and the power supply from the mechanocaloric elements 120a-d to the loading system 140. More precisely, the power transmission is to the at least one mechanocaloric material of the mechanocaloric elements 120a-d, and the power supply is from the at least one mechanocaloric material of the mechanocaloric elements 120a-d to the loading system 140.

[0135] Figure 2 illustrates an example of the measured material characteristics of a mechanocaloric material (in this case of elastocaloric material), wherein it is shown that the force F(s) is a function of the deformation distance s. Illustrated is the force F(s) depending on the deformation distance s for both adiabatic load and adiabatic unload. In some examples, the loading and unloading of the mechanocaloric material of the mechanocaloric elements 120 may be isothermal. Additionally, the force F(s) is dependent on whether the mechanocaloric material is in the loading phase or the unloading phase. Thus, preferably a cam disc 145,146 of the loading system has a shape of the cam profile, which takes into account the different force responses of the mechanocaloric material during loading and unloading.

[0136] Preferably, the loading system 140 is, over an operational cycle, configured to provide a predefined, in particular variable, load on and / or to cause a predefined, in particular variable, deformation of the mechanocaloric material of the mechanocaloric element 120, wherein the load and / or deformation s is determined, in particular as a function over time s(t), independence on characteristics of the mechanocaloric material F(s). More preferably, the characteristics of the mechanocaloric material comprise a stress-strain or pressure-volume response characteristics F(s) of the mechanocaloric material at the relevant conditions, e.g. such as temperature span, ambient temperature, the type of mechanocaloric material, the loading speed and the loading conditions, e.g. adiabatic, isothermal or a mixture of both. The time t herein corresponds to the time of the operational cycle, as during the loading phase and / or unloading phase the load and / or deformation s is changing and preferably is adjusted such that the work provided to or from the mechanocaloric material is constant. In some examples, which comprise cam discs 145,146, such as the example illustrated in Figure 1, the load and / or deformation s is dependent on the cam profile and thus on the rotational angle (p of the cam disc 145,146. The load and / or deformation s, which is required for a preferably constant work to / from the mechanocaloric material of the mechanocaloric elements 120, may thus be determined as a function s(cp), which determines the cam profile.

[0137] In other words, the cam discs 145,146 comprise a cam profile or shape, which produces the reciprocating motion of the cam followers, and the cam profile may be characterized by the displacement diagram, which is showing the movement of the cam followers. Preferably, the cam discs 145,146 are not uniformly shaped, but comprise a cam profile, which is improving the performance of the driving system 100. In this case, the load (e.g. force and / or hydrostatic pressure) applied to the mechanocaloric material of the mechanocaloric elements 120a-d depends on the rotational angle of the cam discs 145,146. Thus, the force and / or mechanical stress applied to the mechanocaloric material of the mechanocaloric elements 120a-d depends on the cam profile of the cam discs 145,146 as the cam discs 145,146 are rotating.

[0138] In some examples, including the example illustrated in Figure 1, the cam discs 145,146 comprise a cam profile, which adjusts the reciprocating motion of the cam followers, i.e. which makes the cam followers not move in a sinusoidal motion or a motion with uniform speed, but in a motion which corresponds to the material properties of the mechanocaloric material of the mechanocaloric elements 120a-d to apply a first constant mechanical input power on the mechanocaloric material and / or receive a second constant mechanical output power from the mechanocaloric material as is shown in Figure 2.

[0139] As described above, the cam profile being the shape (or more precisely the elevation) of the cam disc 145,146 at a given rotational angle (p of the cam disc 145,146 may thus be determined as a function s(cp).Preferably, the cam profile is dependent on above equation

[0140] dW ds

[0141] — — = F(d) — = const,

[0142] dt dt

[0143] The cam disc 145,146 rotates with a constant rotational speed and thus the shape of the cam profile may be determined such that the work W transmitted to / received from the mechanocaloric elements 120 is constant in each time period. The shape of the cam profile depends on the stress-strain response and / or the pressure-volume response characteristics of the at least one mechanocaloric material of the at least one mechanocaloric elements 120.

[0144] In some examples, the cam profile is determined by the required movement of the cam follower 147 in dependence of the stress-strain response and / or the pressure-volume response characteristics of the at least one mechanocaloric material of the at least one mechanocaloric elements 120 to obtain the at least approximately constant mechanical input power and the at least approximately constant mechanical output power.

[0145] Further, the cam profile is determining the operational cycle, i.e. the duration of the loading phase, unloading phase and possible holding phases. The cam profile may be dependent on the number of mechanocaloric elements 120, which are driven by the cam. For example, in the example illustrated in Figure 1, each of the cam discs 145,146 drives two mechanocaloric elements 120a-d, i.e. loads and unloads them. The cam discs 145,146 are arranged at a rotational offset of 90 degrees to one another at the same drive shaft 141. Thereby, as described above, the four mechanocaloric elements 120a-d are having their respective loading and unloading phases at a phase offset of 90 degrees to one another, which results in always the same number of mechanocaloric elements 120a-d being in their respective loading and unloading phases. In combination with the loading system, which cyclically loads each mechanocaloric element 120a-d with the same constant mechanical input power and unloads it with the same constant mechanical output power, the driving system 100 has a constant power input and output throughout the whole operational cycle, because at all time, one of the four mechanocaloric elements 120a-d is in its loading phase and another one of the four mechanocaloric elements 120a-d is in its unloading phase.

[0146] In another example, as introduced above, a single cam disc 145,146 may drive more than two mechanocaloric elements 120a-d. In some examples, each cam disc 145,146 may be configured to drive four mechanocaloric elements, which are arranged around the cam disc 145,146 in 90-degree intervals, similar to the shape of a cloverleaf. The operational cycles of the four mechanocaloric elements may then be shifted to one another by a phase offset of 90 degrees. The number of mechanocaloric elements driven by each cam disc 145,146 may be increased, e.g. to eight mechanocaloric elements driven by each cam disc 145,146. Asdescribed above, more mechanocaloric elements may be driven by the loading system 140 and may e.g. be added above or below the arrangement of mechanocaloric elements shown in Figure 1. In some examples, the at least two mechanocaloric elements 120 may be arranged in a number of layers, wherein each layer comprises at least one mechanocaloric element and at least one loading device. In the example of Figure 1, the mechanocaloric elements 120a-d are arranged in two layers, wherein each layer comprises two mechanocaloric elements 120a-d and one loading device, which is a cam disc 145,146. In some examples, the driving system 100 may comprise another number of mechanocaloric elements. In some examples, the mechanocaloric elements 120 may be arranged in another number of layers. In some examples, the loading devices may be of another type, e.g. a piston. In some examples, another number of mechanocaloric elements 120 may be arranged in each layer. In some examples, different numbers of mechanocaloric elements 120 may be arranged in the various layers. In some examples, further mechanocaloric elements may be added to the driving system 100 at another location or in another direction, e.g. by adding a further drive shaft 141 and utilizing cogs or gears to couple the various drive shafts 141 so that they can transfer mechanical energy between one another.

[0147] Preferably, the number of mechanocaloric elements 120 is chosen in a way, that the combined loading and unloading phases of all the mechanocaloric elements 120 cover the 360 degree of the operational cycle. More preferably, at each time interval of the operational cycle, a number of mechanocaloric elements 120 is in their respective loading phase and the same number of (different) mechanocaloric elements 120 is in their respective unloading phase. Thus, the mechanocaloric elements 120 in their unloading phase may contribute mechanical energy to the loading of the mechanocaloric elements 120 in their loading phases and a constant power input to the mechanocaloric elements 120 and a constant power output from the mechanocaloric elements 120 to the driving system 100 may be realized. In the example illustrated in Figures 1 and 4, wherein the mechanocaloric elements 120 comprise an operational cycle being equally divided into a loading phase, a first holding phase, an unloading phase and a second holding phase, the total number of mechanocaloric elements 120 is preferably a multiple of four to cover the whole range of 360 degree of the operational cycle with loading and / or unloading phases of the mechanocaloric elements 120 and to realize the constant number of mechanocaloric elements being in their loading / unloading phases, this number being one fourth of the total number of mechanocaloric elements 120.

[0148] Figure 3a illustrates the performance of mechanocaloric elements or mechanocaloric regenerators, when loaded and unloaded with a linear displacement loading and unloadingfunction. The mechanocaloric elements or regenerators are respectively phase-shifted by 360° degrees divided by the number of mechanocaloric elements or regenerators. Figure 3b illustrates a linear displacement loading and unloading function. When not loaded with a deformation, pressure and / or force and / or torque, which is customized to the stress-strain or pressure-volume response of the mechanocaloric material as shown in Figure 2, but with a linear displacement function, there will not be a constant loading and unloading power during the operational cycle. The total operational power will also vary over the operational cycle. Figure 3a shows the max and min power or torque obtained during an operational cycle in dependence of the total number of different sets of mechanocaloric element. As more sets of mechanocaloric elements 120 (or mechanocaloric regenerators) are added to the driving system, the difference between the maximum power or torque and the minimum power or torque during the operational cycle decreases. However, such a system will be difficult to build, is very bulky and still has a considerable fluctuation in the moment or torque or force or energy produced. It is thus desirable to have a driving system, which overcomes these drawbacks.

[0149] Figure 4a illustrates an example of an operational cycle of one mechanocaloric element 120 showing the displacement applied to the mechanocaloric element 120 in mm over the duration of an operational cycle, which as an example has a length of 1 second. The deformation changes over time are obtained based on the material response of the corresponding mechanocaloric material. In this example, the operational cycle comprises a loading phase (upward slope) and an unloading phase (downward slope). Additionally, in between the unloading phase and the unloading phase, there is one holding phase each. The loading system 140 is configured to provide at least approximately a constant load on and / or zero deformation and / or constant displacement on the at least one mechanocaloric material of the at least one mechanocaloric element 120 during each holding phase.

[0150] After loading, during the holding phase, a constant (high) load or zero deformation is applied to the mechanocaloric elements 120 (the displacement is thus kept at least approximately constant) during which heat transfer from the at least one mechanocaloric material to a heat sink, e.g. by a heat transfer fluid, occurs. After the unloading, a constant (low or close to zero) load or zero deformation (the displacement is kept at least approximately constant, but on a lower level or even close to zero) is applied to the mechanocaloric elements, and during that holding phase, heat transfer between the at least one mechanocaloric material of the mechanocaloric elements 120 and a heat source occurs.In some examples, the at least approximately constant load may be deviate from a mean constant load value by at most 20 percent. In some examples, the at least approximately constant load may be deviate from a mean constant load value by at most 15 percent. In some examples, the at least approximately constant load may be deviate from a mean constant load value by at most 10 percent. In some examples, the at least approximately zero deformation on the at least one mechanocaloric material of the at least one mechanocaloric element 120 may deviate from a zero deformation position by at most 20 percent of the deformation distance s, which is obtained during the loading phase. In some examples, the at least approximately zero deformation on the at least one mechanocaloric material of the at least one mechanocaloric element 120 may deviate from a zero deformation position by at most 15 percent of the deformation distance s, which is obtained during the loading phase. In some examples, the at least approximately zero deformation on the at least one mechanocaloric material of the at least one mechanocaloric element 120 may deviate from a zero deformation position by at most 10 percent of the deformation distance s, which is obtained during the loading phase. As the load is at least approximately constant and / or the deformation during the holding phase is at least approximately zero, the power acting on or coming from the mechanocaloric material is at least approximately zero. In some examples, the power during the holding phase may deviate around zero by up to 100 percent of the at least approximately constant output power. In some examples, the power during the holding phase may deviate around zero by up to 20 percent of the at least approximately constant output power. In some examples, the power during the holding phase may deviate around zero by up to 15 percent of the at least approximately constant output power. In some examples, the power during the holding phase may deviate around zero by up to 10 percent of the at least approximately constant output power.

[0151] The operational cycle may be characterized by the respective lengths of the loading and unloading phases. The operational cycle may have a duration of e.g. 1 second as in the examples of Figures 4a and 4b. In some examples, including the examples illustrated in Figures 4a and 4b, the loading and the unloading phase have the same length.

[0152] In some examples, including the example of Figure 4a, each of the loading phase, the unloading phase and the two holding phases cover approximately 25% of an operational cycle. In the illustrated example, the loading phase covers the time from 0s to 0.25s, the first holding phase covers the time from 0.25s to 0.5s, the unloading phase covers the time from 0.5s to 0.75s and the second holding phase covers the time from 0.75s to 1s. After 1s, the operational cycle may begin anew with a loading phase. In some examples, the loading and the unloading phases may be longer and the holding phases may be shorter. In someexamples, the loading and the unloading phase may cover up to 50% of the operational cycle with the two holding phases covering the rest of the operational cycle going down to 0%, where the holding phases are omitted and loading and unloading phases are directly after one another. In some examples, the two holding phases each cover at most 20% of the operational cycle. In some examples, the two holding phases each cover at most 15% of the operational cycle. In some examples, the two holding phases each cover at most 10% of the operational cycle. In some examples, the two holding phases each cover at most 5% of the operational cycle. In some examples, the two holding phases each cover at most 3% of the operational cycle. In some examples, the two holding phases each cover at most 2% of the operational cycle. In some examples, the two holding phases each cover at most 1% of the operational cycle.

[0153] Figure 4b illustrates an example of an operational cycle of an embodiment comprising four sets of mechanocaloric elements 120, such as the mechanocaloric elements 120a-d of the example illustrated in Figure 1. Similarly to Figure 4b, the deformation applied to the mechanocaloric elements 120a-d in mm is illustrated over the time corresponding to a whole operational cycle. The deformation changes over time are obtained based on the material response of the corresponding mechanocaloric material. The different coloured graphs are showing the deformation for each of the different mechanocaloric elements 120a-d, e.g. green being for mechanocaloric element 120a, red being for mechanocaloric element 120b, blue being for mechanocaloric element 120c, and yellow being for mechanocaloric element 120d. The loading phases, holding phases and unloading phases of the mechanocaloric elements 120 are out of phase with respect to each other, in particular in a way that the unloading phase of one of the mechanocaloric elements 120 contributes energetically to the loading phase of one of the other mechanocaloric elements 120. Preferably, each of the mechanocaloric elements contributes in its unloading phase energetically to the loading phase of one of the other mechanocaloric elements 120. Preferably, the four mechanocaloric elements 120 are loaded and unloaded phase-shifted by 90 degrees with respect to one another, 90 degrees being equal to a quarter of a whole operational cycle as a whole operational cycle contains 360 degrees phase angle.

[0154] More general, the arrangement may comprise a number of sets of mechanocaloric elements 120, wherein the loading and unloading phases of the respective sets of mechanocaloric elements (120) are phase-shifted by 360 degrees divided by the number of sets of mechanocaloric elements (120). In some examples, the arrangement may comprise eight mechanocaloric elements 120, wherein the operation cycles of the mechanocaloric elements are shifted by 45 degrees, respectively.Figure 5a illustrates the torque of a mechanocaloric driving system, when loaded and unloaded with a loading and unloading function based on the material response of the mechanocaloric material, which ensures the constant power approach. In this exemplary embodiment, the driving system is a driving system 100 as introduced with respect to Figure 1. The driving system 100 comprises multiple sets of mechanocaloric elements 120. In this example, the operational cycle has a length of 1s.

[0155] As can be seen in the top graph of Figure 5a, the torque acting on the mechanocaloric elements 120 is constant over time during the loading. More precisely, the load torque is constant over the whole operational cycle, i.e. the torque from the loading system 140, which is exerted on the mechanocaloric elements 120 is constant during the whole operational cycle. The loading system 140 of this example comprises an electric motor, which actuates or rotates cam discs 145,146 with cam followers 147 and pistons 127, which load and unload the mechanocaloric elements 120. In this example, the driving system 100 comprises four mechanocaloric elements 120 and the four mechanocaloric elements 120 are arranged in four sets, such that they are loaded and unloaded in 90° phase offset with respect to one another. The loading phases of the different mechanocaloric elements 120 are distributed over the operational cycle such that at each time during the operational cycle, one of the mechanocaloric elements 120 is currently in its loading phase. This way, during the whole operational cycle, the same load torque is required by the mechanocaloric elements 120 and the loading system 140 or the electric motor provides said constant load torque during the whole operational cycle. Preferably, the loading is adiabatic. As can be seen in the bottom graph of Figure 5a, the torque provided from the mechanocaloric elements 120 to the loading system 140 during unloading is also constant over the whole operational cycle. The total torque required from the driving system 100 for driving the mechanocaloric elements 120 can thus be described as the difference of the torque required for loading the mechanocaloric elements 120 minus the torque provided from the mechanocaloric elements 120 during unloading. The total torque is illustrated in the middle graph of Figure 5a.

[0156] Figure 5b illustrates the mechanical power of a mechanocaloric driving system, when loaded and unloaded with a loading and unloading function based on the material response of the mechanocaloric material, which ensures the constant power approach.

[0157] In this exemplary embodiment, the driving system is a driving system 100 as introduced with respect to Figure 1. The driving system 100 comprises multiple sets of mechanocaloric elements 120. In this example, the operational cycle has a length of 1s.As can be seen in the top graph of Figure 5b, the power acting on the mechanocaloric elements 120 is constant over time during the loading. More precisely, the loading power is constant over the whole operational cycle, i.e. the power from the loading system 140 or the electric motor, which is exerted on the mechanocaloric elements 120 is constant during the whole operational cycle. In this example, the driving system 100 comprises four mechanocaloric elements 120 and the four mechanocaloric elements 120 are arranged in four sets, such that they are loaded and unloaded in 90° phase offset with respect to one another. The loading phases of the different mechanocaloric elements 120 are distributed over the operational cycle such that at each time during the operational cycle, one of the mechanocaloric elements 120 is currently in its loading phase. This way, during the whole operational cycle, the same loading power is required by the mechanocaloric elements 120 and the loading system 140 provides said constant loading power during the whole operational cycle. As can be seen in the bottom graph of Figure 5b, the power provided from the mechanocaloric elements 120 to the loading system 140 during unloading is also constant over the whole operational cycle. The total power required from the driving system 100 for driving the mechanocaloric elements 120 can thus be described as the difference of the power required for loading the mechanocaloric elements 120 minus the power provided from the mechanocaloric elements 120 during unloading. The total power is illustrated in the middle graph of Figure 5b.

[0158] Figure 6a illustrates experimental data of the produced torque of an exemplary arrangement of sets of mechanocaloric elements 120, the sets comprising one, two and four mechanocaloric elements 120. As can be seen, the torque required by a single set of mechanocaloric elements 120 is positive during loading and negative during unloading, and zero during the holding phases. Further, the torque required by each single set of mechanocaloric elements 120 is at least approximately constant respectively during each of the loading, unloading and holding phases. Shown is also the torque of two sets of mechanocaloric elements, which are operated opposite in phase, e.g. the mechanocaloric elements 120a and 120b of the exemplary embodiment of Figure 1. These mechanocaloric elements 120a and 120b are loaded and unloaded with a phase-offset of 180° and thus their combination yields a total torque, which is approximately constant during the loading and unloading phases and approximately zero during the holding phases. Similarly, the total torque by all four sets of mechanocaloric elements 120, e.g. the four mechanocaloric elements 120a-d of the example of Fig. 1, are yielding an at least approximately constant total torque over the entire cycle.The operational cycle may not only be characterized by the duration or the portion of the duration, but also by the rotation of the cam discs 145,146 and the drive shaft 141. As one revolution of the drive shaft 141 and the cam discs 145,146 equals one operational cycle in the example of Figure 1 and the operational data from Figure 6a and 6b refers to this exemplary setup, the operational cycle may be described by the shaft rotation in degrees, whereas a whole revolution of the drive shaft 141 of 360 degrees equals one operational cycle.

[0159] Figure 6b illustrates experimental data of the load and displacement of each of the four mechanocaloric elements and torque of an exemplary arrangement of four mechanocaloric elements 120. As can be seen, the displacement of the various mechanocaloric elements 120 is similar to the displacement as shown in Figure 4b. The resulting torque is the torque as shown in Figure 6a. The force acting on the mechanocaloric material of the mechanocaloric elements 120 is not linear during the loading and unloading phases to provide the at least approximately constant input and output power as was discussed with reference to the material characteristics of the mechanocaloric material in Figure 2.

[0160] As previously disclosed, there may be several reasons for a deviation from the ideal constant input and output power. For example, the ideal cam profile may be a cam profile, which cannot be manufactured. Also, production tolerances may create deviations from an ideal cam profile. Further, the mechanocaloric material may not have an ideal response characteristics as theoretically predicted or measured, as the mechanocaloric material may comprise impurities, cracks, defects, etc. Thus, there will be a deviation from an ideal constant input power and / or output power. The driving system 100 as disclosed herein provides an improved setup with multiple advantages over the prior art aiming at improving the uniformity of the input power and output power. As disclosed above, the at least approximately constant mechanical input and / or output power may thus deviate around a mean mechanical input / output power by a value, e.g. by a value of up to 100% of the mean value.

[0161] Comparing to a driving system as in the prior art, e.g. as disclosed with respect to Figure 3a, an improvement in performance is achieved. Comparing to Figure 3a, Figure 6b illustrates experimental data of a setup with four mechanocaloric elements or mechanocaloric regenerators. Over a whole operational cycle (one shaft rotation of 360°), the torque deviates from about 10Nm to 20Nm, which can be described as a mean of 15Nm with fluctuations of 5Nm. The deviation is thus about 33% of the mean value.Comparing to a linear deformation approach during loading and unloading as described with respect to Figures 3a and 3b, there is a maximum torque of 70Nm and a minimum torque of -30Nm with a discrepancy of the high and low torque values of 100Nm. Having a similar mean value, the deviation from the mean value is thus 100Nm / 15Nm, which is over 600%. The power input / output of this approach yields much higher deviations and a much less constant power, which is a disadvantage as described above.

[0162] The driving system 100 according to this disclosure thus provides an advantageous driving system for a mechanocaloric heating or cooling apparatus.

[0163] Figure 7 illustrates an example of a driving system 100, which is configured to drive a mechanocaloric heating or cooling apparatus. The driving system 100 of Figure 7 is similar to the driving system 100 as disclosed with respect to Figure 1. The person skilled in the art will understand, that for the sake of brevity, the features of Figure 1 are not repeated here, but that the driving system 100 of Figure 7 may comprise any features disclosed with respect to Figure 1 or any of the other Figures or sections of this disclosure.

[0164] The loading system 140 comprises four force amplifier 160a-d, each of the force amplifiers 160a-d is arranged at one of the individual mechanocaloric elements 120a-d. In another example, the loading system 140 may comprise a different number of force amplifiers 160a-d. Preferably, the loading system 140 comprises one force amplifier 160 for each mechanocaloric element 120, wherein one force amplifier 160 is arranged at each individual mechanocaloric element 120.

[0165] The force amplifiers 160a-d are arranged between the cam follower 147 and the mechanocaloric elements 120a-d and are configured to transfer energy and power therebetween.

[0166] In some examples, the loading system 140 may comprise force amplifiers 160, and may not comprise cam discs 145,146 and cam followers 147, but other means to load and unload the mechanocaloric elements 120. Generally speaking, the force amplifiers 160 may be arranged between the means to load and unload the mechanocaloric elements 120 and the mechanocaloric elements 120 to transfer energy and power therebetween and to amplify the force acting on the mechanocaloric elements 120.As an example, a hydraulic force amplifier 160a-d amplifies a force Fi at a first side to a force F2 on a second side depending on the ratio of the cross sections Ai and A2 of the hydraulic pistons at the first and second side.

[0167] Fi ■ Ai —2■ A2

[0168] Further, the work on both sides of the force amplifier 160 is constant, such that the product of the displacements di and d2and cross sections A1 and A2 are the same for the first and second side.

[0169] c?i ■ Ai = d2■ A2

[0170] Thus, the force applied is inverse to the displacement of the piston at the respective side.

[0171] d2■ i = c?i ■ F2

[0172] As the force amplifiers 160 reduce the power on the side of the cam follower 147 (generally speaking, on the side of the means for loading and unloading the mechanocaloric elements 120), the displacement as higher at that side. This is advantageous, as the larger displacement at the side of the cam follower 147 allows for a larger error tolerance of the cam profile or means for loading and unloading. For example for a cam disc setup, as described in this disclosure, the cam disc 145,146 is designed to control the loading and unloading of the mechanocaloric elements 120 such that the input and output power during loading and unloading is at least approximately constant, respectively. The manufacturing of the cam discs 145,146 is subject to precision errors and the ideal cam disc 145,146 may have a profile, which cannot be exactly manufactured with real world tools. The deviation from the ideal cam profile of the cam discs 145,146 is an absolute error and results in a deviation from the ideal movement of the cam follower 147. As the total displacement is larger when using the force amplifiers 160, the relative error of this deviation in comparison to the total displacement of the cam follower 147 gets smaller. The smaller relative error of the movement of the cam follower 147 equals a smaller relative error in the at least approximately constant power on / from the mechanocaloric elements. In short, the deviation from the ideal loading and unloading of the mechanocaloric elements 120 due to a deviation of the cam profile of the cam discs 145,146 from the ideal cam profile of the cam discs 145,146 has less negative effects when the force amplifiers 160 are used. Further, the force amplifiers reduce the power and force that the power transmission components, such as e.g. drive shafts, bearings, shaft couplings, hydraulic elements and tubings etc., are operating on. This enables to utilize minimal dimensions, configuration and design, and mass of the powertransmission components such as drive shafts, bearings, shaft couplings, hydraulic elements and tubings etc., as there is no requirement for withstanding a higher load during operation. As the power transmission components may be made smaller, the loading system 140 and / or the driving system 100 may be built smaller and / or lighter, which facilitates production and transport.

[0173] In some examples, the force amplifiers 160 are hydraulic, pneumatic, mechanical, electric or of another type of force amplifiers.

[0174] The force amplifiers 160a-d reduce the force to / from the cam discs 145,146, cam followers 147, shaft and bearings during operation. With reduced force, there is less friction and less mechanical loss, which improves the efficiency of the driving system and the mechanocaloric heating or cooling apparatus.

[0175] The force amplifiers 160 may have an elongation, e.g. a hydraulic force amplifier 160 may comprise a tubing between a piston on the first side and a piston on the second side to transfer energy and power between the two sides. The tubing may be elongated to enable to arrange the first side and the second side spaced apart. This way, piston at the first end of the force amplifier 160 may be arranged at the cam follower 147 and the second end of the force amplifier 160 may be arranged at a distal position. At said distal position, there may be an arrangement of multiple mechanocaloric elements 120. This way, the mechanocaloric elements 120 may be arranged close to one another, which may facilitate transport, installation and maintenance, and may result in a more compact design. This setup may also facilitate transport, installation and maintenance of the cam discs 145,146, cam followers 147 and drive shaft 141 as it is easier to access these parts without the mechanocaloric elements 120 being arranged around them.

[0176] In some examples, this disclosure relates to a mechanocaloric device, which comprises a driving system 100, and a heat transfer system, which is configured to transfer heat to or from the mechanocaloric elements 120 of the driving system 100 to the ambient or heat sinks or heat sources. In some examples, the heat transfer system may comprise a heat transfer fluid, which is in contact with the mechanocaloric material of the mechanocaloric elements and is propelled by a propulsion device, e.g. a pump, to transport heat from the mechanocaloric material to a heat sink and transport heat from a heat source to the mechanocaloric material.Fig. 8 illustrates an example of friction and hysteresis effects on the loading system 140 of the driving system 100, which is illustrated in Fig. 7.

[0177] The dotted graph at the bottom of the drawing illustrates an idealized case with no losses, no friction within the driver cam mechanism, in particular the cam shaft 141 and the cam discs 145, 146 and the cam followers 147, and no hysteresis in the mechanocaloric elements 120a-d. The required torque on the cam shaft 141 to rotate the cam disc 145, 146 for loading the mechanocaloric elements 120a-d is approximately constant with a value pf 0 Nm. The energy obtained from the unloading of the mechanocaloric material of the mechanocaloric elements 120a-d is transmitted back to the cam discs 145, 146 via the cam followers 147 during the respective unloading cycle. Thus, the energy obtained from the unloading mechanocaloric elements 120a-d drives the cam discs 145, 146 and the cam shaft 141 and can be reused to load the respective mechanocaloric elements 120a-d in their loading phase.

[0178] As the same number of mechanocaloric elements 120a-d are in their respective loading phase as the number of mechanocaloric elements 120a-d in their respective unloading phase (in this example, there is always one mechanocaloric element 120a-d loading and another mechanocaloric element 120a-d unloading during the whole operational cycle as explained in detail above), the energy required for loading the mechanocaloric elements 120a-d matches the energy obtained from unloading the mechanocaloric elements 120a-d and generally, there is no torque required from any drive means to provide further energy / torque to the cam discs 145, 146 to drive the operation of the driving system 100.

[0179] Though not shown in this example, the required torque may deviate around the 0 Nm line. This so-called fluctuation ripple may be due to geometry errors due to production of the driving system 100 or mechanocaloric materials in the mechanocaloric elements 120a-d and / or due to their material characteristics.

[0180] The dashed graph with short dashes in the middle of the drawing illustrates a case with hysteresis present in the mechanical response of mechanocaloric elements 120a-d but without frictional or other system losses. In this case, the required torque on the cam shaft 141 to rotate the cam discs 145, 146 deviates around a mean torque of 8 Nm. The hysteresis in the mechanocaloric material of the mechanocaloric elements 120a-d represent losses and return less energy during unloading of the mechanocaloric material with respect to the loading of another mechanocaloric element 120a-d, i.e. the returned energy / torque is lower than the required energy / torque for loading another mechanocaloric element 120a-d. Thus, a higher input of torque / energy is required to drive the rotation of the cam shaft 141 and thecam discs 145, 146 and the operation of the driving system 100. Similarly, as explained above, there may also be fluctuation ripple, which is not illustrated in the dashed graph.

[0181] At the top of the drawing, there are two different graphs, a dashed graph with long dashes and a graph with drawn-through line.

[0182] The dashed graph with long dashes illustrates a case incorporating both hysteresis losses in the mechanocaloric elements 120a-d and frictional losses within the driving system 100. As described in more detail below, the frictional losses are dependent on multiple variables, in particular on the rotational position of cam shaft 141 and the cam discs 145, 146 and the resulting forces on the cam followers 147 and other components. As these variables change other the operational cycle, i.e. during the loading and unloading of the mechanocaloric elements 120a-d and the rotation of the cam discs 145, 146, the effects on the cam discs 145, 146 and the cam shaft 141 are time-dependent, in particular they are dependent on the rotational angle of the cam shaft 141 or the cam discs 145, 146.

[0183] In the dashed graph with long dashes, the cam disc geometry takes into account hysteresis, but does not account for friction-induced losses, resulting in a deviation from the ideal torque profile and a required torque, which is highly time-dependent and dependent on cam shaft rotation and cam disc rotation.

[0184] As can be seen in the dashed graph with long dashes, the effects of friction losses change with rotation of the cam shaft 141 and the cam discs 145, 146 and the with chance of the force acting on the cam followers 147 and the mechanocaloric elements 120a-d.

[0185] For example, in Fig. 8, at 0° cam shaft rotation, a first mechanocaloric element 120a of the mechanocaloric elements 120a-d has just finished its loading phase and is at maximum deformation and a maximum force is acting on the respective cam followers 147 and optionally on the force amplifier 160a. A second mechanocaloric element 120c of the mechanocaloric elements 120a-d has just finished its holding phase and is at minimum deformation and a minimum force is acting on the respective cam followers 147 and optionally on the force amplifier 160c. A third mechanocaloric element 120b of the mechanocaloric elements 120a-d has just finished its unloading phase and is at minimum deformation and a minimum force is acting on the respective cam followers 147 and optionally on the force amplifier 160b. A fourth mechanocaloric element 120d of the mechanocaloric elements 120a-d has just finished its holding phase and is at maximum deformation and a maximum force is acting on the respective cam followers 147 and optionally on the force amplifier 160d.At 90° cam shaft rotation, the corresponding phases of each mechanocaloric regenerator have moved by 90° phase. The first mechanocaloric element 120a of the mechanocaloric elements 120a-d has just finished its holding phase and is at maximum deformation and a maximum force is acting on the respective cam followers 147 and optionally on the force amplifier 160a. The second mechanocaloric element 120c of the mechanocaloric elements 120a-d has just finished its loading phase and is at maximum deformation and a maximum force is acting on the respective cam followers 147 and optionally on the force amplifier 160c. The third mechanocaloric element 120b of the mechanocaloric elements 120a-d has just finished its holding phase and is at minimum deformation and a minimum force is acting on the respective cam followers 147 and optionally on the force amplifier 160b. The fourth mechanocaloric element 120d of the mechanocaloric elements 120a-d has just finished its unloading phase and is at minimum deformation and a minimum force is acting on the respective cam followers 147 and optionally on the force amplifier 160d.

[0186] Thus, at both these positions, there is a maximum force acting on two of the respective cam followers 147 and optionally on the force amplifiers 160a-d and further parts of the loading system 140. However, at the 0° cam disc or cam shaft rotation position, the two mechanocaloric elements 120a, 120d, on which the maximum force is acting, are arranged at opposite sides of the cam discs 145, 146 and the cam shaft 141. Thus, the forces acting on the respective cam followers 147 and the cam discs 145, 146 apply in opposite direction and reduce the friction forces, in particular the radial forces acting on the cam discs 145, 146 and the cam shaft 141.

[0187] In contrast, at the 90° cam disc or cam shaft rotation position, the two mechanocaloric elements 120a, 120c, on which the maximum force is acting, are arranged at the same side of the cam discs 145, 146 and the cam shaft 141. Thus, the forces acting on the respective cam followers 147 and the cam discs 145, 146 apply in the same direction and the corresponding friction forces add up, in particular the radial forces acting on the cam discs 145, 146 and the cam shaft 141.

[0188] The graph with drawn-through line illustrates the case for the driving system 100 according to a preferred embodiment. In this preferred example, the most dominant forms of energy dissipation (not only frictional but also hysteresis, hydraulic, structural, or otherwise) are anticipated and incorporated in this approach and are taken into account for the determination of the cam profile. Thus, the design of the cam disc 145, 146, in particular the cam profile s(cp), is determined to ensure an approximately constant power / torque responsethroughout the operational cycle. Driving the driving system 100 according to this preferred example with a constant torque on the cam shaft 141 and / or cam discs 145, 146, facilitates driving by drive means and minimizes torque ripple, minimises system size, reduces wear, and improves overall efficiency. To determine the design of the loading system 140, in particular the cam profile s(cp) of the cam discs 145, 146, at least the most dominant forms of energy dissipation may be taken into account, which will be described in detail below.

[0189] During the operation of the loading system 140, which in particular may be a cam-driven mechanism, several forms of internal energy dissipation arise. The dominant contributions are associated with frictional phenomena, which may manifest either as sliding friction or rolling friction, depending on the local kinematics of the interface of the loading system 140, in particular of the cam followers 147. One example may be rolling friction for cam followers 147 comprising rollers 148, which create friction at the rotating cam discs 145, 146.

[0190] Additional losses may emerge from hydraulic subsystems such as force amplifiers 160a-d as well as from internal material damping and hysteresis in structural components subjected to cyclic loading. Collectively, these mechanisms influence the overall efficiency, torque stability, and operational performance of the system.

[0191] Friction in loading system 140, in particular in loading system 140 comprising cam followers 147, can occur in at least three principal forms, which are the most dominant contributors to energy dissipation:

[0192] The first principal form of friction is sliding friction, which is dominant when relative tangential motion occurs at the contact interface of the loading system 140, which is typical for flat cam followers 147 or geometric configurations with nonideal rolling and sliding bearings. The second principal form of friction is rolling friction, for example rolling contact in roller bearings of the loading system 140, such as rolling contact of the cam followers 147 on the cam discs 145, 146, etc. Further, as the cam followers 147 may be connected to force amplifiers 160a-d, which comprise pistons arranged inside cylinders, there is also friction at the seals of the pistons, when the pistons are moved in the cylinders. The third principal form of friction is internal fluid friction, which is dependent on the viscosity of the fluid and the fluid velocity in the fluid lines and the cylinders of the force amplifiers 160a-d, the shape of the crosssections of the fluid lines and the length of the fluid lines, as well as pressure / load and temperature of the fluid in the force amplifiers 160a-d. The internal fluid friction may be determined using CFD simulation.

[0193] The instantaneous sliding friction force is described by:

[0194] Fsl - HslF nwheres / is the sliding friction coefficient and Fnthe normal force at the interface. The work dissipated during a cycle is:

[0195] Wsi= f Fsids

[0196] Rolling friction is e.g. present when the cam follower 147 incorporates a rolling element (e.g., a roller bearing or a roller 148), significantly reducing but not eliminating frictional losses due to rolling resistance, internal bearing losses, and micro-slip.

[0197] Rolling friction (or rolling resistance) is typically much smaller than sliding friction and arises from deformation losses in the roller 148, cam surface, and bearing elements. The rolling resistance force may be expressed as:

[0198] Frail ~ FnCr I Troll

[0199] The rolling resistance force may be expressed as:

[0200] f roll ~ FnCr

[0201] where Cris the rolling resistance coefficient and rmii the effective rolling radius. The corresponding energy dissipation per cycle is:

[0202] Wroll—f Frollds — f Mrooldd

[0203] Friction forces become significant when high normal loads are present.

[0204] Mechanocaloric elements 120a-d introduce a highly nonlinear dynamic loading profile characterized by stress-induced phase transformation, pronounced hysteresis, and ratedependent mechanical response. These effects produce rapid temporal variations in normal force Fn(t) which directly affect both sliding and rolling friction forces as well as internal fluid friction forces. Because Fn(t) can exhibit sharp peaks, both sliding and rolling friction losses as well as internal fluid losses become strongly time-dependent.

[0205] The driving torque of the loading system 140, in particular a drive means driving the loading system 140, e.g. a drive means rotating the cam discs 145, 146, must overcome not only the load imposed by the mechanocaloric elements 120a-d but also the frictional resistance and other losses.

[0206] Even when the cam profile is designed using a constant power / torque approach taking into account the material characteristics, such as the stress-strain response and / or the pressurevolume response characteristics, the presence of friction-induced force components introduces deviations from the ideal torque profile. In combination with mechanocaloricelement hysteresis, these effects may significantly influence torque ripple, efficiency, and mechanical stability if they are not considered in the construction of the cam disc shape in the constant-power approach.

[0207] Accurate evaluation of sliding and rolling friction may be conducted using a multilevel methodology:

[0208] Analytical models allow closed-form estimation of sliding friction, rolling resistance, internal fluid friction and cycle-integrated energy dissipation based on measured force-displacement relations.

[0209] Numerical simulations (finite-element analysis and multibody dynamics) enable the incorporation of linear and nonlinear material laws, advanced friction models

[0210] (Coulomb, Stribeck, rolling resistance models), and time-varying normal forces.

[0211] Experimental characterization through torque transducers, rotary encoder, high-resolution displacement / force measurements, and comparative work-input / output analyses provides empirical validation.

[0212] The combination of these approaches ensures that frictional losses (sliding and rolling and internal fluid friction) are properly captured within the model of the loading system 140, in particular the model for creating the cam profile of the cam discs 145, 146.

[0213] Given the significant impact of both sliding and rolling friction on system performance, these effects may be incorporated into the design and optimization of the loading system 140, in particular the design and optimization of the cam profile s(cp) of the cam discs 145, 146. Neglecting friction may lead to inaccurate torque predictions, suboptimal efficiency, increased wear, and potentially unstable operation.

[0214] Therefore, in a preferred example, the loading system 140, in particular the cam profile s(cp), may be developed from a comprehensive model that integrates:

[0215] • dynamic normal force evolution,

[0216] • sliding and rolling friction contributions,

[0217] • internal fluid friction

[0218] • material properties of the mechanocaloric material, in particular stress-strain response or pressure-volume response, and

[0219] • mechanocaloric element hysteresis.

[0220] Preferably, as shown in the graph with drawn-through line of Fig. 8, the most dominant forms of energy dissipation (not only frictional but also hysteresis, hydraulic, structural, orotherwise) are anticipated and incorporated in this approach and are taken into account for the determination of the properties of the loading system 140, in particular the cam profile of the cam discs 145, 146. Thus, the design of the loading system 140, in particular the cam profile s(cp) of the cam discs 145, 146, is determined based on calculations, which take into account the most dominant forms of energy dissipation to ensure an approximately constant power / torque response throughout the operational cycle. The design of the loading system 140, in particular the cam profile s(cp) of the cam discs 145, 146, may be determined based on the required movement of the loading system 140, in particular the cam followers 147 in dependence of the most dominant forms of energy dissipation in particular dynamic normal force evolution, sliding and rolling friction contributions, internal fluid friction, material properties of the mechanocaloric material, in particular stress-strain response or pressurevolume response, and mechanocaloric element hysteresis, to obtain the approximately constant mechanical input power on the mechanocaloric elements 120a-d and / or cam shaft 141 during loading phase and an approximately constant mechanical output power from the mechanocaloric elements 120a-d and / or cam shaft 141 during unloading phase. This approach facilitates driving the loading system 140, in particular the cam discs 145, 146 and / or cam shaft 141, and minimizes torque ripple, minimises system size, reduces wear, and improves overall efficiency as illustrated in Fig. 8.

Claims

1. 47CLAIMS1. A driving system (100), in particular for a mechanocaloric heating, cooling or dehumidifying apparatus, the driving system (100) comprising:an arrangement with at least a first set and a second set of mechanocaloric elements, wherein each set comprises at least one mechanocaloric element (120), each mechanocaloric element (120) comprising at least one mechanocaloric material, anda loading system (140), which is configured to load and unload the first set and the second set of mechanocaloric elements (120) in a plurality of consecutive operational cycles by applying a deformation and / or mechanical load, in particular a shape or volume change, to the at least one mechanocaloric element (120), andwherein, in each operational cycle, the loading system (140) is configured to cyclically load and unload the first and second set of mechanocaloric elements (120), such that during a respective loading phase of the first and second set of mechanocaloric elements an at least approximately constant mechanical input power is applied on the mechanocaloric elements (120), andsuch that during a respective unloading phase of the first and second set of mechanocaloric elements an at least approximately constant mechanical output power is applied from the mechanocaloric elements (120) on the loading system (140).

2. The driving system (100) according to claim 1, wherein the loading system (140) has a total operational power, which is the difference between the input power applied on the mechanocaloric elements (120) and the output power applied from the mechanocaloric elements (120) on the loading system (140), and wherein the total operational power is at least approximately constant over an operational cycle.

3. The driving system (100) in accordance with any one of the preceding claims, wherein, in each operational cycle, the first set of mechanocaloric elements (120) is loaded and unloaded phase-shifted with respect to the loading and unloading of the second set of mechanocaloric elements (120), preferably phase-shifted by 180°.

4. The driving system (100) in accordance with any one of the preceding claims, wherein the loading system (140) is over an operational cycle at least temporarily in contact with each mechanocaloric element (120), and48wherein the loading system (140) is configured to provide the approximately constant mechanical input power by a defined movement of at least a portion of the loading system (140) with respect to the mechanocaloric elements (120).

5. The driving system (100) in accordance with any preceding claim,wherein the loading system (140) comprises at least one cam disc (145,146) having a cam profile, wherein the cam disc (145,146) rotates during the operational cycle, and wherein the loading system further comprises at least one cam follower (147) for each of the mechanocaloric elements (120), which are configured to move with respect to the respective mechanocaloric elements (120), and wherein the cam profile, during rotation of the cam disc (145,146), acts on the cam followers (147) to provide the approximately constant mechanical input power during loading of the respective mechanocaloric elements (120) and to ensure an approximately constant mechanical output power from the respective mechanocaloric elements (120) during unloading.

6. The driving system (100) in accordance with claim 5,wherein the cam profile is dependent on the loading and / or unloading material properties of the mechanocaloric material of the mechanocaloric elements (120) such that the loading and / or unloading power is at least approximately constant.

7. The driving system (100) in accordance with any one of claims 5 or 6, wherein the cam profile is determined by the required movement of the cam follower (147) in dependence of the stress-strain response and / or the pressure-volume response characteristics of the at least one mechanocaloric material of the at least one mechanocaloric elements (120) to obtain the at least approximately constant mechanical input power and the at least approximately constant mechanical output power.

8. The driving system (100) in accordance with any one of claims 1 to 4,wherein the loading system (140) comprises at least one piston to load and unload the mechanocaloric elements (120), wherein the loading system (140) is configured to move the piston to provide the approximately constant mechanical input power during loading of the mechanocaloric elements (120) and to ensure an approximately constant mechanical output power from the mechanocaloric elements (120) during unloading.

9. The driving system (100) in accordance with any one of the preceding claims,49wherein, over an operational cycle, the loading system (140) is configured to provide a predefined, in particular variable, load on and / or to cause a predefined, in particular variable, deformation of the mechanocaloric element (120).

10. The driving system (100) in accordance with claim 9,wherein the load and / or the deformation is determined, in particular as a function over time, in dependence on characteristics of the mechanocaloric material of the respective mechanocaloric element (120).

11. The driving system (100) in accordance with any one of the preceding claims, wherein each operational cycle includes holding phases between the loading and / or unloading phases of the respective sets of mechanocaloric elements, wherein, preferably, the loading system (140) is configured to provide at least approximately a constant load on and / or constant deformation on the at least one mechanocaloric material of the at least one mechanocaloric element (120) during each holding phase.

12. The driving system (100) in accordance with claim 11, wherein a holding phase is longer or shorter than a loading phase or an unloading phase.

13. The driving system (100) in accordance with any one of the preceding claims, wherein the loading phase and the unloading phase cover the same amount of an operational cycle.

14. The driving system (100) in accordance with any one of the preceding claims, wherein the loading system (140) is configured to couple the first set and the second set of mechanocaloric elements (120) such that the unloading phase of one set of mechanocaloric elements (120) contributes energetically to the loading phase of the other set of mechanocaloric elements (120).

15. The driving system (100) in accordance with any one of the preceding claims, wherein the arrangement comprises a number of sets of mechanocaloric elements (120), wherein the loading and unloading phases of the respective sets of mechanocaloric elements (120) are phase-shifted by 360 degrees divided by the number of sets of mechanocaloric elements (120).

16. The driving system (100) in accordance with any one of the preceding claims, wherein the loading system (140) comprises one force amplifier (160) for each50mechanocaloric element (120), and wherein one force amplifier (160) is arranged at each individual mechanocaloric element (120).

17. The driving system (100) in accordance with any one of the preceding claims, wherein the design of the loading system (140), in particular the cam profile s(cp) of the cam discs (145, 146), is determined based on the required movement of the loading system (140), in particular the cam followers (147) in dependence of the most dominant forms of energy dissipation in particular dynamic normal force evolution, sliding and rolling friction contributions, internal fluid friction, material properties of the mechanocaloric material, in particular stress-strain response or pressure-volume response, and mechanocaloric element hysteresis, to obtain the approximately constant mechanical input power on the mechanocaloric elements (120a-d) and / or cam shaft (141) during loading phase and an approximately constant mechanical output power from the mechanocaloric elements (120a-d) and / or cam shaft (141) during unloading phase.

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