Clamping device, clamping fixture and elastocaloric machine with a clamping device

Abstract

The invention relates to a clamping device for holding an elastocaloric element for an elastocaloric machine, which is configured to be operated as a heat pump and / or refrigeration machine, wherein the clamping device comprises: at least one elastocaloric element, which is formed from an elastocaloric material and configured to assume a first state in which, based on the elastocaloric effect, the elastocaloric material releases heat energy, and a second state in which, based on the elastocaloric effect, the elastocaloric material absorbs heat energy; a holder configured to hold one end of the elastocaloric element such that, in conjunction with a corresponding holder, the holder varies the distance between the held ends of the elastocaloric element within a working range during operation of the elastocaloric machine.to transfer the elastocaloric element from one state of the first state and the second state to the other, wherein the holder comprises a holder holding the end of the elastocaloric element and a guide which interact in such a way that relative movement between the holder and the guide is permitted in one direction and blocked in the opposite direction.

Description

[0001] The invention relates to a clamping device for an elastocaloric machine and to a clamping device with such a clamping device.

[0002] Furthermore, the invention relates to an elastocaloric machine with such a clamping device.

[0003] Elastocaloric machines are conventionally operated as heat pumps and / or refrigeration machines, for example in the form of air conditioning systems, in motor vehicles.

[0004] Such elastocaloric machines traditionally use elastocaloric elements made of elastocaloric materials, particularly so-called shape memory alloys (SMA). In such pseudoelastic alloys, a significant deformation can be induced by the introduction of heat from a heat source. If the alloy releases the heat again when the heat source is removed, the metal returns to its original shape. This effect is completely reversible. Along with this, the reverse effect, the so-called elastocaloric effect, is utilized. By changing the shape of the elastocaloric material using corresponding clamping devices, which will be explained in more detail below, the heat of transformation of the elastocaloric material is exchanged with the environment, so that the elastocaloric material can assume a lower energy state after exchanging heat energy with the environment, i.e., the state prior to the heat energy exchange.In particular, for the application and exploitation of the elastocaloric effect, the elastocaloric material is stretched, which corresponds to a first state explained below, in order to release heat energy, and relaxed, which corresponds to a second state explained below, in order to absorb heat energy.

[0005] Specifically, the elastocaloric material is subjected to mechanical stress by means of the corresponding restraints, for example, stretching as mentioned above, resulting in a crystalline phase transformation and heating. This resulting heat is dissipated, for example, via a heat sink, so that the material cools back to its initial temperature. If the mechanical stress is then removed, i.e., the material relaxes, the order decreases, and the material cools even below its initial temperature, so that it can now absorb thermal energy or heat energy from the environment.

[0006] By cyclical loading and unloading, or expansion and relaxation, of the elastocaloric material using the corresponding clamping devices, a corresponding heat supply and removal can be achieved in the sense of an elastocaloric heat pump. By appropriately controlling the cyclic loading, or expansion and unloading, or relaxation, combined with appropriate control of a fluid circuit, which may, for example, contain a coolant such as water, a heat pump or refrigeration machine can be realized using the elastocaloric machine.

[0007] The introduction of mechanical forces onto the elastocaloric elements made of elastocaloric material in order to load or stretch them accordingly is conventionally carried out via the above-mentioned two corresponding and opposing clampings of the clamping device, via which tensile stresses of up to 1000 MPa can be applied.

[0008] The elastocaloric elements made of elastocaloric material or the wires of the wire bundles can be designed in the form of, for example, thin strips, tubes or round wires, with the intention of providing the largest possible elastocaloric volume with the largest possible surface area of ​​the elastocaloric material for heat dissipation and heat absorption.

[0009] Such two corresponding clamps hold and move an elastocaloric element within a channel of the elastocaloric machine that carries a fluid and is usually designed in the form of a cylindrical shell or a hollow cylinder, and place the elastocaloric element in the said first state, in which the elastocaloric element releases heat energy to the fluid due to the elastocaloric effect, and in a second state, in which the elastocaloric element absorbs heat energy from the fluid due to the elastocaloric effect.

[0010] In particular, the corresponding clamps hold and move a respective elastocaloric element made of elastocaloric material or the bundle(s) of elastocaloric material between them within the channel. For example, the clamps move a respective elastocaloric element or one or more bundles of elastocaloric material along the channel, in particular in the circumferential direction in the case of an annular channel viewed in cross-section, while loading and unloading the respective elastocaloric element in a direction that is perpendicular to the direction of movement of the respective elastocaloric element, i.e., parallel to a rotation axis of the elastocaloric machine. The bundle(s) held between the respective clamps is / are thereby loaded (stretched) and unloaded (relaxed).To move the respective elastocaloric element or wire bundle(s) held between the corresponding clamps from the first state to the second state and vice versa, the corresponding clamps undergo a reciprocating motion while being moved in the circumferential direction of the channel. This means that the distance between the corresponding clamps changes between a minimum distance and a maximum distance, with the difference between the two distances being the stroke, which is predetermined by the design of the elastocaloric machine.

[0011] Fig. Figure 1 shows a perspective view of a section of an elastocaloric machine 1' in a longitudinal section. As can be seen particularly in Fig. As can be seen in Figure 1, the elastocaloric machine 1' holds a plurality of elastocaloric elements 10' via corresponding clamps 100' of a clamping device 1000' in a cylindrical channel 12', wherein the plurality of elastocaloric elements 10' is moved about a rotational axis A within the channel 12' and is thereby stretched (loaded) and relaxed (unloaded) in a conventional manner not described in detail, i.e., is moved within the stroke. The stretching of the elastocaloric elements 10' or the wires of a bundle of elastocaloric material is initiated, for example, by a cam. The wires are firmly clamped at the other end. This is done via the respective two corresponding clamping devices 100', namely a clamping device 100' initiating the lifting movement and a clamping device 100' fixed in the longitudinal direction of the elastocaloric machine 1', which are shown as an example in section and in an enlarged view in Fig. 2. Thus, a respective elastocaloric element 10' made of elastocaloric material, or the bundle(s) of elastocaloric material, is held between the corresponding clamps 100' within the channel 12'. Stretching of the elastocaloric element 10' or the wires of the bundle releases latent heat. The amount of stretching controls the proportion of the wire material that is converted from austenite to martensite.

[0012] Due to the periodic expansion and relaxation of the elastocaloric elements or the wire bundle(s) made of elastocaloric material in a correspondingly large number, relaxation of the elastocaloric element held between the clamps occurs. Therefore, the elastocaloric elements or the wire bundle(s) made of elastocaloric material are usually prestressed to counteract this relaxation, i.e., the plastic expansion of the wires.

[0013] According to the state of the art, measures have been taken to compensate for this relaxation of the elastocaloric element or the wire bundle(s) made of elastocaloric material.

[0014] Fig. 3 shows a schematic representation of a clamping device 1000' known from the prior art. As can be seen therefrom, a holder 20' is movably guided in the direction of the rotation axis A via a linear guide, namely via the interaction of a movable sleeve 21', which is connected to the holder 20' via a screw connection 22' and which is laterally engaged with a guide 23' in the form of a lead screw, which predetermines the linear degree of freedom in the direction of the rotation axis A. The sleeve 21' is held in place by a spring 24' in the zero stroke range, ie at the minimum distance between the two corresponding clamping devices 100' (only one is in Fig. 3), preferably in a direction away from the holder 20' or in the direction of extension of the elastocaloric element 10'. If the corresponding clamping device 100' performs a lifting movement, as mentioned above, the elastocaloric element 10' or the wire bundle(s) can be stretched by up to 7%, whereby stresses of up to 1000 MPa can occur.

[0015] Considering the number of wires in the wire bundle and the total cross-section of the wires per wire bundle, it is not intended to be dimensioned as a preload spring for space reasons to the extent that it can fully counteract the forces occurring during the lifting movement. The spring therefore only serves to preload the wires of the wire bundle in the zero-stroke range and does not prevent the clamping fixture from maintaining its position in its zero position while the other corresponding clamping fixture performs the lifting movement.

[0016] In the example of Fig. 3, the sleeve 21' is first pulled against the force of the preload spring 24' in the stroke range against a housing block 25' acting as a stop, and is guided axially by the guide screw. After the sleeve 21' is pulled against the stop, the wires of the wire bundle(s) can be tensioned.

[0017] Since the stroke specified by the cam, or rather the extent of the stroke movement, is constant, the maximum cam stroke cannot be used to stretch the wires due to the spring travel. Accordingly, the maximum elongation of the wires in the wire bundle is not achieved, which is noticeable in reduced latent heat, since the entire microstructure in the wire cannot be converted from austenite to martensite.

[0018] While the prior art clamping device prevents mechanical damage due to loose wires in the zero-stroke range and enables quasi-automatic preloading via the spring, this is accompanied by performance losses in the stroke range when the sleeve is pulled to its stop. This is a disadvantage, especially in the series production of such clamping devices, with regard to the continuously decreasing cooling / heating performance of the elastocaloric machine over the product's lifetime.

[0019] Fig. 4 shows a schematic representation of another clamping device 1000' known from the prior art, wherein Fig. 4a a first state of the clamping device 1000' and Fig. 4b shows a second state of the clamping device 1000'.

[0020] In Fig. Figure 4a shows a clamping arrangement 100' in which the prestress of the elastocaloric element or the wires of the wire bundle(s) can be manually adjusted. The prestress counteracts the relaxation of the wires of the wire bundle(s), thus preventing, for example, mechanical damage caused by loose wires. In the specific case of Fig. 4a is a roller 26', which in Fig. 4b, when the wire bundle is in the zero-stroke range, is removed in order to then manually adjust the pretension; this is accomplished by a relative rotation of a holder 20' engaging an internal thread of an adapter sleeve 21', against which the wire bundle engages. The roller 26' is then reassembled, as shown in Fig. 4b. Advantageous compared to the clamping device of Fig. 3 in this case is that after pre-tensioning the wires, the full cam stroke can be used to stretch the wires. However, one disadvantage is that the pre-tensioning process is not automatic, and the elastocaloric machine must be disassembled for manual adjustment. In a series application, pre-tensioning the wires therefore involves maintenance costs to ensure the cooling / heating performance guaranteed by the manufacturer.

[0021] Against this background, it is the object of the present invention to provide a clamping device, a clamping device and an elastocaloric machine with which the heating and / or cooling efficiency can at least be maintained compared to the prior art.

[0022] This object is achieved by a clamping device according to claim 1, a clamping device according to claim 11 and an elastocaloric machine according to claim 12.

[0023] Advantageous embodiments and further developments of the invention emerge from the dependent claims.

[0024] The clamping device according to the invention is intended for holding an elastocaloric element, in particular a wire bundle or a plurality of wire bundles made of elastocaloric material, for an elastocaloric machine which is designed to be operated as a heat pump and / or refrigeration machine, wherein the clamping device comprises: at least one elastocaloric element ora wire bundle which is formed from an elastocaloric material and is configured to assume a first state in which the elastocaloric material releases heat energy on the basis of the elastocaloric effect, and to assume a second state in which the elastocaloric material absorbs heat energy on the basis of the elastocaloric effect, a holder which is configured to hold one end of the elastocaloric element in such a way that the holder, in cooperation with a corresponding holder, maintains a distance between the held ends of the elastocaloric element within a working range ora range of a stroke movement is varied in order to transfer the elastocaloric element from one state of the first state and the second state to the other state, wherein the holder has a holder holding the end of the elastocaloric element and a guide, which interact in such a way that a relative movement between the holder and the guide is permitted in one direction and is blocked in the opposite direction. Preferably, the relative movement is permitted in a direction of extension or loading of the elastocaloric element and blocked in the direction of unloading. By allowing the relative movement between the holder and the guide in this direction, an automatic adjustment of the preload is possible when the elastocaloric element is preloaded in one direction or its direction of extension. Because upon relaxation of the elastocaloric element, ieDuring its plastic deformation, the interaction of holder and guide automatically enables the relative movement of one end of the elastocaloric element with appropriate preload, for example by means of a preload spring.

[0025] The clamping according to the invention enables the elastocaloric elements or the wire bundle(s) made of elastocaloric material to be automatically pre-tensioned, thus avoiding manual and potentially costly pre-tensioning. Therefore, the provision of automatic pre-tensioning does not negatively affect the cooling / heating performance of the machine, as is the case, for example, with the prior art solutions according to Fig. 3 and Fig. 4 is the case, but rather maintains it. Furthermore, the automatic prestressing can be designed so that it can be easily and automatically installed as an additional module. Prestressing can take place virtually automatically, regardless of whether it is based on a mechanical principle using a prestressing spring or an electromechanical principle using an actuator. This eliminates associated maintenance costs, and prestressing occurs before mechanical damage to the elastocaloric element can occur, for example, due to loose wires in a wire bundle. Such improved component protection is not achieved through manual prestressing according to the state of the art.

[0026] The clamping device according to the invention can advantageously be further developed such that the guide has a locking device that engages with the holder in such a way that the holder is enabled to move relative in one direction and blocks relative movement in the opposite direction. The locking device can, for example, be implemented as a snap-in / sliding connection, which, by engaging the guide, allows the holder to move relative in one direction but blocks it in the other.

[0027] Furthermore, the clamping according to the invention can be implemented such that the locking device has a pawl and the holder has a toothing, wherein the pawl engages with the toothing of the holder such that the holder is allowed relative movement in one direction and the relative movement in the opposite direction is blocked. For example, the locking device can have a locking housing with the guide and the pawl, which is designed such that it allows the holder to move in one direction and blocks it in the opposite direction. Thus, after pre-tensioning the wires in the zero-stroke range of the cam, a full cam stroke and thus full elongation can be used to tension the wires of the wire bundle made of elastocaloric material. Thus, there is no loss of performance after pre-tensioning the wires.The locking housing is preferably designed in a modular manner so that it can be adapted to different loads (two locking pawls or more). Furthermore, the locking housing is preferably designed so that it can be easily pushed onto the pull rod as a completely prefabricated subassembly during assembly and automatically pushed to its final position.

[0028] Furthermore, the clamping according to the invention can be implemented in such a way that the locking device has two or more pawls and the holder is designed as a rod or pull rod with the toothing, wherein the two or more pawls are arranged distributed at predefined intervals in the circumferential direction with respect to the rod.

[0029] In this context, the clamping according to the invention can be realized in such a way that the toothing has a plurality of teeth and the two or more pawls engage in teeth at different heights in the toothing direction.

[0030] Furthermore, the clamping device according to the invention can be designed in such a way that the toothing of the rod has at least two toothing sections in the longitudinal direction of the rod, which are formed with a different pitch and / or arranged in a phase-shifted manner. The locking housing can thus be modularly adapted to tie rods with phase-shifted toothing, so that the preload can be applied in steps corresponding to one tooth height up to steps corresponding to a quarter of the tooth height.

[0031] Furthermore, the clamping device according to the invention can be further developed such that the toothing of the rod is designed such that toothing sections with the same pitch or with the same phase position are opposite one another with respect to a cross section of the rod.

[0032] Furthermore, the clamping according to the invention can be such that the holder has a force application device, preferably a modular force application device, which is designed to apply a force to the holder which acts in one direction.

[0033] Furthermore, the clamping device according to the invention can be implemented such that the holder has a preloading device configured to preload the holder in one direction. The preloading device can be, for example, a preloading spring, but alternative preloading devices such as an electromechanical actuator are also conceivable.

[0034] Furthermore, the clamping device according to the invention can be designed such that the pretensioning device has a stop connected to the holder and a spring which is designed to press against the stop.

[0035] The clamping device according to the invention is provided for the elastocaloric machine and comprises: at least two corresponding clamps which are configured to hold, preferably to hold and move, an elastocaloric element within a fluid-conducting channel of the elastocaloric machine, and to place the elastocaloric element into a first state in which the elastocaloric element releases heat energy to the fluid due to the elastocaloric effect, and to place it into a second state in which the elastocaloric element absorbs heat energy from the fluid due to the elastocaloric effect, wherein one of the at least two corresponding clamps is formed by the clamp according to the invention.Accordingly, one clamping device is formed by the clamping device according to the invention and thus represents a fixed clamping device, while the corresponding other clamping device is the one which carries out the lifting movement by specifying a cam.

[0036] The elastocaloric machine according to the invention is designed to be operated as a heat pump and / or refrigeration machine and comprises: a channel which is designed in the form of a cylindrical shell or hollow cylinder and is designed to guide a fluid in a flow direction predetermined by the channel, and a plurality of clamping devices according to the invention which are distributed in the circumferential direction along the channel in the form of the cylindrical shell at predefined intervals.

[0037] As a result, the properties and advantages explained in connection with the clamping device according to the invention result in the same or similar way, which is why, in order to avoid repetition, reference is made to the above statements with regard to the clamping device according to the invention.

[0038] Preferred embodiments of the invention are explained below by way of example with reference to the figures.

[0039] They show: Fig. 5a, b schematic representations of a section of an elastocaloric machine according to the invention in a longitudinal section view ( Fig. 5a) and an enlarged section of the elastocaloric machine according to the invention, in which a clamping according to the invention is shown enlarged ( Fig. 5b); Fig. 5c is a schematic cross-sectional view of a clamping device according to the invention according to a first embodiment of the invention; Fig. 6 is a schematic cross-sectional view of a clamping device according to the invention according to a second embodiment of the invention; Fig. 7a, b schematic representations of a clamping device according to the invention in cross section and in perspective view according to a third embodiment of the invention; Fig. 8a, b are schematic representations of a clamping device according to the invention in cross-section and in perspective view according to a fourth embodiment of the invention; and Fig. 9 a schematic representation of a clamping device according to the invention in cross section and in perspective view during assembly of the locking device.

[0040] Fig. 5a and Fig. 5b show schematic representations of a section of an elastocaloric machine 1 according to the invention in a longitudinal sectional view ( Fig. 5a) and an enlarged section of the elastocaloric machine 1 according to the invention, in which a clamping device 100 according to the invention is shown enlarged ( Fig. 5b). The elastocaloric machine 1 according to the invention is in this case configured to operate as a heat pump and refrigeration machine.

[0041] As can be seen from the Fig. 5a and Fig. 5b, the elastocaloric machine 1 according to the invention and the one known from the prior art and described in Fig. The elastocaloric machine 1' shown in Figure 1 is constructed largely identically. However, there are differences, particularly with regard to the clamping elements 100 and 100' fixed in the longitudinal direction of the elastocaloric machine 1, and the associated clamping devices 1000 and 1000', which will become apparent below.

[0042] The elastocaloric machine 1 according to the invention holds a plurality of elastocaloric elements 10 via corresponding clamping devices 100, 100' of a plurality of clamping devices 1000 according to the invention in a cylinder jacket-shaped channel 12. The channel 12 is designed in the form of a cylinder shell or hollow cylinder and carries a fluid to be cooled or heated in a flow direction predetermined by the channel 12, ie in a circumferential direction with respect to the axis of rotation A, as shown in Fig. 5a is shown.

[0043] The expansion of the elastocaloric elements 10 or the wires of a bundle of elastocaloric material is initiated, for example, by a cam. At the other end, the wires are firmly clamped. This is achieved, on the one hand, by a clamping device 100' that initiates the lifting movement, as is also shown in Fig. 1, and secondly via a clamping device 100 according to the invention which is fixed in the longitudinal direction of the elastocaloric machine 1.

[0044] Between these corresponding clamps 100' and 100, a respective elastocaloric element 10 made of elastocaloric material or the bundle(s) made of elastocaloric material is held within the channel 12.

[0045] Fig. 5c shows a schematic representation of the inventive fixed clamp 100 in cross section according to a first embodiment of the invention.

[0046] The multiple clamping devices 1000 are thus, as further shown Fig. 5a, are distributed at predefined intervals in the circumferential direction along the channel 12 in the form of the cylinder shell and each comprise two corresponding clamps 100' and 100, which are configured to hold a respective elastocaloric element 10 in the form of a wire bundle or multiple wire bundles made of elastocaloric material within the channel 12 and to move it in its circumferential direction. Furthermore, the two corresponding clamps 100' and 100 place the elastocaloric element 10 into a first state in which the elastocaloric element 10 releases heat energy to the fluid due to the elastocaloric effect, and into a second state in which the elastocaloric element 10 absorbs heat energy from the fluid due to the elastocaloric effect.

[0047] For this purpose, one of the two corresponding clamps 100' performs or initiates a lifting movement during one revolution, i.e., during a 360° movement within the channel 12 around the rotation axis A, in order to place the elastocaloric element 10 into the corresponding first or second state. The other clamp 100 according to the invention of the two corresponding clamps 100' and 100 also moves together with the one clamp 100' and performs the 360° movement within the channel 12 around the rotation axis A. However, this does not perform a lifting movement, but, as already indicated above, is a fixed clamp with respect to the longitudinal direction of the rotation axis A of the elastocaloric machine 1.

[0048] While one clamping device 100' thus loads and relieves the elastocaloric element 10 due to the lifting movement by applying a tension load to and then relieving a tension rod supporting one end of the elastocaloric element 10 via a holder, the other clamping device 100 according to the invention also has a holder 20 configured to hold another end of the elastocaloric element 10. The elastocaloric element 10 is held such that the holders of both corresponding clamping devices 100' and 100 vary a distance between the held ends of the elastocaloric element 10 within a working range or the range of the lifting movement during operation of the elastocaloric machine 1 in order to transfer the elastocaloric element 10 from one state of the first state and the second state to the other state.

[0049] The holder 20 of the other clamping device 100 according to the invention comprises a holder 30 in the form of a rod, in particular a tension rod, which holds the end of the elastocaloric element 10, and a guide 40 which interact in such a way that relative movement between the holder 30 and the guide 40 is permitted in one direction and blocked in the opposite direction, namely in the direction of extension or tension of the elastocaloric element 10 and blocked in the direction of unloading. This is achieved structurally in that the guide 40 has a locking device 42 which engages with the holder 30 in such a way that the holder 30 is permitted to move relative in one direction and blocks relative movement in the opposite direction.

[0050] In particular, the locking device 42 has a pawl 41 and the holder 30 has a toothing 31, wherein the pawl 41 engages in the toothing 31 of the holder 30 such that the holder 30 is allowed to move relative in one direction and the relative movement in the opposite direction is blocked.

[0051] According to the first embodiment according to Fig. 5, the locking device 42 has precisely one pawl 41, and the holder 30, designed as a rod or pull rod, is formed with the corresponding toothing 31 into which the pawl 41 engages. The pawl 41 is rotatably mounted in one direction of rotation, which corresponds to the direction of extension or tension of the elastocaloric element 10, and locks accordingly in the other direction of rotation.

[0052] Furthermore, the holder 20 comprises a pretensioning device 60, which is configured to pretension the holder 30 in one direction, or in the direction of extension, of the elastocaloric element 10. For this purpose, the pretensioning device 60 is equipped with a stop 61, which is firmly connected to the holder 30 in the form of a rod, and a spring 62, which is supported on an element of the clamping device 100 (not described in detail), for example, a housing section of the elastocaloric machine 1, and presses against the stop 61. For example, the stop 61 is designed in the form of a threaded nut and is screwed onto a thread of the holder 30, which is designed as a tension rod. As a result, the holder 30 and thus the elastocaloric element 10 are always pretensioned.

[0053] The clamping device 100 according to the first embodiment thus enables prestressing of the elastocaloric element 10 or the wire bundle made of elastocaloric material without loss of strain due to relaxation. On the holder 30 in the form of a tension rod, to which the elastocaloric element 10 or the wire bundle is attached, are the toothing 31 and the thread onto which the nut acting as a stop 61 is screwed. The nut has a disc-shaped section that acts as a stop surface, acts on the spring 62, and thereby prestresses the holder 30 in the form of a tension rod and, accordingly, the wire bundle made of elastocaloric material.

[0054] In the illustrated case, a locking housing 64 is formed, which forms the guide 40 in sections and receives and holds the pawl 41 together with the holder 30. The pawl 41 is rotatably mounted and is pressed against the toothing 31 by a pawl spring 43 such that the pawl 41 permits movement of the holder 30 in the form of a pull rod only in the tensile or stretching direction of the elastocaloric element 10, otherwise it blocks. Therefore, if a force acts on the elastocaloric element 10 or the wire bundle in the stroke range that is greater than the force of the preload spring 62, the design of the locking device 42 leads to self-locking of the system, and the holder 30 does not move with respect to the guide 40.

[0055] Fig. Figure 6 shows a schematic cross-sectional view of a clamping device 100 according to the invention according to a second embodiment of the invention. The description of this second embodiment will only focus on the differences from the first embodiment, with identical or similar components being designated by the same reference numerals.

[0056] In this embodiment, the locking device 42 has exactly two pawls 41, wherein the two pawls 41 are arranged at predefined intervals, in this case offset by 180°, distributed in the circumferential direction with respect to the rod or pull rod and engage at the same height in the holder 30 in the form of the rod.

[0057] The clamping device 100 according to this second embodiment is particularly suitable in conjunction with elastocaloric elements 10 or wire bundles made of elastocaloric material with an increased number of wires and thus increased wire mass, in order to generate more latent heat, thereby reducing the surface pressure between the locking pawl 41 and the rack or holder 30 in the form of the rod with toothing 31 to an adequate level. Of course, the number of locking pawls is variable and can be expanded to three or more locking pawls, thus absorbing further increased wire bundle forces.

[0058] Fig. 7a, b show schematic representations of a clamping device 100 according to the invention in cross-section and in perspective view according to a third embodiment of the invention. In the description of this third embodiment, only the differences from the second embodiment will be discussed, with identical or similar components being designated by the same reference numerals.

[0059] In this embodiment, the locking device 42 has four locking pawls 41, wherein the four locking pawls 41 are distributed at predefined intervals in the circumferential direction with respect to the holder 30 in the form of a rod and additionally engage the toothing 31 at different heights. Thus, two opposing locking pawls 41 engage the toothing 31 at the same height, while two opposing locking pawls 41, offset by 90°, engage the toothing 31 at a different location and at different heights.

[0060] In this case, the toothing 31 is provided with two toothing sections, each with a plurality of teeth, wherein the two toothing sections are formed with a different pitch in the longitudinal direction of the rod and preferably also phase-shifted, i.e., shifted in the longitudinal direction of the rod relative to the respective other toothing section. The toothing sections, with the same pitch, lie opposite one another with respect to a cross-section of the holder 30 in the form of the rod and are preferably not phase-shifted relative to one another, i.e., they have the same phase position.

[0061] Thus, the toothing 31 of the pull rod differs from that of the second embodiment in that the respective opposing toothing sections on the pull rod, thus a total of four toothing sections, have the same tooth arrangement / pitch and are not phase-shifted relative to one another, while the respective adjacent toothing sections are phase-shifted relative to the other two opposing toothing sections and preferably also have a different pitch. Accordingly, the teeth of the respective toothing sections, which have different pitches, are arranged in different numbers with respect to the rod's longitudinal direction. The teeth of the respective toothing sections can also be arranged phase-shifted with respect to the rod's longitudinal direction.

[0062] This allows for pre-tensioning of the wire bundles in finer increments. For example, in this embodiment, the toothing can be provided with a pitch or phase shift, in which two opposing toothing sections have a toothing with half the tooth height of the two remaining opposing toothing sections. For example, for wire bundles with a smaller number of wires, and thus also lower acting forces, the locking housing 64 can be designed with only two pawls 41 and a total of two toothings that are phase-shifted from one another. The pre-tensioning occurs in increments corresponding to half the tooth height.

[0063] However, designs with three pawls and three toothings on the pull rod that are offset relative to one another are also conceivable, so that the preload can be adjusted in steps corresponding to one third of the tooth height.

[0064] Furthermore, a design is also conceivable in which four pawls and four toothings offset relative to one another are provided, so that the preload can be adjusted in steps corresponding to a quarter of the tooth height.

[0065] Fig. 8a and b show schematic representations of a clamping device 100 according to the invention in cross-section and in perspective view according to a fourth embodiment of the invention. In the description of this fourth embodiment, only the differences from the second embodiment will be discussed, with identical or similar components being designated by the same reference numerals.

[0066] In the illustrated case, the holder 20 further comprises a force application device 50, for example in the form of an electromechanical actuator, which is configured to apply a force to the holder 30 in the form of a pull rod, which force acts in one direction or the direction of extension of the elastocaloric element 10. Accordingly, the locking housing 64 is provided with a bore 52, so that the force application device 50 can be brought into mechanical or magnetic engagement with an upper end of the holder 30 in the form of a pull rod via a housing bore 72 of a machine housing section 70 and can apply a tensile force to the pull rod. Therefore, the preload can be adjusted via the force application device 50 in cooperation with the locking device 42, whereby the stop 61 in the form of a nut and the preload spring 62 can be omitted in this embodiment, but need not be.

[0067] For example, the force application device 50 in the form of the actuator can be attached to the machine housing section 70 of the elastocaloric machine 1, as shown in Fig. 8a. Each wire bundle can thus be individually pre-tensioned using the actuator. This is done, for example, using a defined routine in which, for example, the operating time of the machine, the duration of the load conditions, and other measured variables are included as parameters, so that the pre-tension can be periodically adjusted or readjusted when starting up or shutting down the elastocaloric machine 1.

[0068] Fig. 8b shows a retracted state (left) and an extended state (right) of the actuator, whereby the actuator can connect to the pull rod or engage with the pull rod, for example by means of an electromagnet, but also mechanically, for example via a screw connection with the pull rod.

[0069] Fig. Figure 9 shows a schematic representation of a clamping device 100 according to the invention in cross-section and in perspective view during the assembly of the locking device 42. Essentially, the locking device 42 can be plugged onto the holder 30 in the form of a pull rod from above and thereby engaged with the pull rod. The locking housing 64 is thus designed such that it can be automatically pushed onto the pull rod as an assembly or module in a single, simple step until it reaches its final position. The housing can then also be automatically screwed into place.

[0070] The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for the realization of the invention both individually and in any combination.

Claims

[1] Clamping device (100) for holding an elastocaloric element (10) for an elastocaloric machine (1) which is designed to be operated as a heat pump and / or refrigeration machine, the clamping device (100) comprising: at least one elastocaloric element (10) which is formed from an elastocaloric material and is configured to assume a first state in which, on the basis of the elastocaloric effect, the elastocaloric material releases heat energy, and to assume a second state in which, on the basis of the elastocaloric effect, the elastocaloric material absorbs heat energy, a holder (20) which is designed to hold one end of the elastocaloric element (10) in such a way that the holder (20), in cooperation with a corresponding holder, varies a distance between the held ends of the elastocaloric element (10) within a working range during operation of the elastocaloric machine (1) in order to transfer the elastocaloric element (10) from one state of the first state and the second state to the other state, wherein the holder (20) comprises a holder (30) holding the end of the elastocaloric element (10) and a guide (40) which cooperate in such a way that a relative movement between the holder (30) and the guide (40) is permitted in one direction and is blocked in the opposite direction. [2] Clamping device (100) according to claim 1, wherein the guide (40) has a locking device (42) which engages with the holder (30) so that the holder (30) is allowed the relative movement in one direction and the relative movement in the opposite direction is blocked. [3] Clamping device (100) according to claim 2, wherein the locking device (42) has a pawl (41) and the holder (30) has a toothing (31), wherein the pawl (41) engages in the toothing (31) of the holder (30) in such a way that the holder (30) is allowed the relative movement in one direction and the relative movement in the opposite direction is blocked. [4] Clamping device (100) according to claim 3, wherein the locking device (42) has two or more pawls (41) and the holder (30) is designed as a rod with the toothing (31), wherein the two or more pawls (41) are arranged distributed at predefined intervals in the circumferential direction with respect to the rod. [5] Clamping device (100) according to claim 4, wherein the toothing (31) has a plurality of teeth and the two or more pawls (41) engage with teeth at different heights in the toothing direction. [6] Clamping device (100) according to claim 4 or 5, wherein the toothing (31) of the rod has at least two toothing sections in the longitudinal direction of the rod, which are formed in a different pitch and / or arranged out of phase. [7] Clamping device (100) according to one of claims 3 to 6, wherein the toothing (31) of the rod is designed such that toothing sections with the same pitch or with the same phase position are opposite one another with respect to a cross section of the rod. [8] Clamping device (100) according to one of the preceding claims, wherein the holder (20) has a force application device (50), preferably a modular force application device (50), which is designed to apply a force to the holder (30) which acts in one direction. [9] Clamping device (100) according to one of the preceding claims, wherein the holder (20) has a pretensioning device (60) which is arranged to pretension the holder (30) in the one direction. [10] Clamping device (100) according to claim 9, wherein the pretensioning device (60) comprises a stop (61) connected to the holder (30) and a spring (62) which is arranged to press against the stop (61). [11] Clamping device (1000) for an elastocaloric machine (1) which is designed to be operated as a heat pump and / or refrigeration machine, the clamping device (1000) comprising: at least two corresponding clamps (100, 100') which are designed to hold an elastocaloric element (10) within a fluid-conducting channel (12) of the elastocaloric machine (1) and to place the elastocaloric element (10) into a first state in which the elastocaloric element (10) releases heat energy to the fluid due to the elastocaloric effect, and to place it into a second state in which the elastocaloric element (10) absorbs heat energy from the fluid due to the elastocaloric effect, wherein one of the at least two corresponding clamps (100, 100') is formed by a clamp (100) according to one of the preceding claims. [12] Elastocaloric machine (1) which is designed to be operated as a heat pump and / or refrigeration machine, comprising: a channel (12) which is designed in the form of a cylinder shell / hollow cylinder and is arranged to guide a fluid in a flow direction predetermined by the channel (12), and a plurality of clamping devices (1000) according to claim 11, which are distributed circumferentially along the channel (12) in the form of the cylinder shell at predefined intervals.

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