Vacuum cooling device and method for vacuum cooling a product

Abstract

The invention relates to a vacuum cooling device (1, 1', 1'') comprising at least one first vacuum cooling chamber (A - D), which, in a closed state, can be evacuated to a first pressure level lower than an ambient pressure of the vacuum cooling device (1, 1', 1'') for vacuum cooling a product (P) accommodated therein, and at least one second vacuum cooling chamber (B) arranged immediately downstream of the first vacuum cooling chamber (A) in the transport direction (T), within which, in the closed state, either a second pressure level lower than the first pressure level of the first vacuum cooling chamber (A) can be generated or within which a second pressure level corresponding at most to the ambient pressure of the vacuum cooling device (1, 1', 1'') is enclosed, wherein the first vacuum cooling chamber (A) and the second vacuum cooling chamber (B) can be connected to one another to establish pressure equalization (K, K', K'') of the first pressure level and the second pressure level.Furthermore, the invention relates to a method for vacuum cooling of products (P).

Description

The present invention relates to a vacuum cooling apparatus according to claim 1. further the invention relates to a method for vacuum cooling a product according to claim 11.DE29607689U1 discloses a thermoform packaging machine having a sealing station, downstream of which is arranged a mechanical cooling device in the production direction, which presses from above and from below onto sealed packages by means of cooling pads mounted thereon in order to cool them downstream of the sealing station after the sealing process.JPS57-1021A discloses a thermoform packaging machine having a forming station for producing thermoform troughs, which forming station is positioned at the beginning in the production direction, a sealing station for producing packages and a vacuum station positioned between the forming station and the sealing station in order to remove moisture from products enclosed therein, whereby these can be cooled.US 2004 / 0105927A1 discloses a thermoform packaging machine having a pasteurization station which is positioned upstream of a sealing station of the thermoform packaging machine in the production direction. products arriving therein can be heat-treated by means of steam feed within the pasteurization station. Optionally, a vacuum cooling process takes place subsequent to the pasteurization process.DE1020202012848A1 discloses a thermoform packaging machine having a vacuum cooling station positioned along a filling line of the thermoform packaging machine for cooling the troughed products by means of a generated vacuum in successive steps prior to a sealing process.During the vacuum cooling of hot products, for example baked goods or, for example, pre-cooked foods, such as mouth pockets, water vapor forms in the product, since the water bound in the product boil below the saturated vapor pressure. A side effect of this evaporation is the cooling of the product, since the energy required for the water to phase transition is extracted from the product. In this case, the product in the interior and / or its casing can be damaged on account of the suddenly arising gas. Also during the subsequent venting of a vacuum chamber, products accommodated therein and cooled beforehand by means of vacuum generation, in particular products which have cavities in the interior, for example leaf dough pastries in the form of croissants, can be damaged by the venting pressure applied to the product from the outside, in particular by an abruptly increasing venting pressure.Vacuum cooling stations integrated on thermoform packaging machines have the disadvantage that the product has to be cooled over several cycles in order to achieve the desired cycle performance of the thermoform packaging machines. For this purpose, several cooling chambers must be inserted one after the other, which are evacuated and aerated several times in successive steps. By opening and closing the vacuum cooling chambers or venting the individual cycles to ambient pressure in order to further transport the working cycles, a large total amount of energy required for generating the vacuum per vacuum cooling process is consumed. Moreover, the complete opening and closing of the vacuum chambers and the resulting need to bring the respective vacuum chambers successively and again from the ambient pressure to a predetermined pressure level requires a certain time, which impairs the rate of application of the vacuum cooling process.The object of the invention is to provide a device and a method for energy-efficient, in particular gentle vacuum cooling of products. This object is achieved by means of a vacuum cooling device according to claim 1.Advantageous refinements of the invention are given by the respective subject matters of the dependent claims.The invention relates to a vacuum cooling device comprising at least one first vacuum cooling chamber which, in a closed state, can be evacuated to a first pressure level for vacuum cooling of a product accommodated therein. Furthermore, the vacuum cooling device comprises at least one second vacuum cooling chamber arranged directly downstream of the first vacuum cooling chamber in the production direction, within which, in the closed state, either a second pressure level that is lower than the first pressure level of the first vacuum cooling chamber can be generated, or within which a second pressure level that corresponds at most to the ambient pressure of the vacuum cooling device is included. According to the invention, the first vacuum cooling chamber and the second vacuum cooling chamber can be connected to one another in order to produce a pressure compensation of the first pressure level and of the second pressure level.By pressure equalization, it is possible that the vacuum cooling chamber that includes a lower internal pressure than the other vacuum cooling chamber lowers the output pressure of the other vacuum cooling chamber. Thus, the vacuum cooling chamber, in which the output pressure for the evacuation has been lowered by pressure equalization, can be evacuated with less energy consumption than would be the case if the pressure equalization between the vacuum cooling chambers had not been carried out. In other words, the evacuation of the vacuum cooling chamber with higher included pressure level from the other vacuum cooling chamber with lower included pressure level as a result of the pressure compensation can be assisted with a view to an energy-efficient operation of the vacuum cooling device.In the invention, a pressure equalization carried out between different pressure levels of adjacent vacuum cooling chambers can thus bring about a reduction in the energy consumption during the evacuation of the vacuum cooling chambers. In the invention, the energy already used for evacuating one of the vacuum chambers can therefore be used at least partially for evacuating the other vacuum cooling chamber by pressure equalization with the other vacuum chamber, in order to carry out the vacuum cooling process in an overall more energy-efficient manner.According to one embodiment of the invention, it is provided that the first vacuum cooling chamber and the second vacuum cooling chamber are connected by means of a bypass line that can be controlled for producing the pressure compensation. A flow through the bypass line could be controlled by means of a valve unit integrated therein. The low pressure level generated by the one vacuum cooling chamber, which can be in particular a vacuum cooling chamber arranged downstream in the transport direction, can be applied via the bypass line to the other vacuum cooling chamber, which can be in particular a vacuum cooling chamber arranged upstream in the transport direction, in order to assist this during evacuation. On the basis of the bypass line, the vacuum generated in one of the two vacuum chambers can be used via the bypass line in order to bring the relatively higher pressure level located therein in the other vacuum chamber to a lower pressure level by means of the pressure equalization, from which the two vacuum cooling chambers, in particular the vacuum cooling chamber brought to a lower pressure level by means of the pressure equalization, can be evacuated further.Preferably, a partition wall is arranged between the first vacuum cooling chamber and the second vacuum cooling chamber, said partition wall being displaceably mounted between a closed position, in which the vacuum cooling chambers are separated from one another, and an open position, in which the vacuum cooling chambers are joined together for transporting the product from the first into the second vacuum cooling chamber. In the joined state, the two vacuum cooling chambers together enclose a vacuum cooling chamber formed substantially from the sum of the individual vacuum cooling chambers, in which the pressure level resulting from the pressure equalization is enclosed. From this pressure level, the combined vacuum cooling chamber can be evacuated further.It is conceivable that the pressure compensation can be produced on the basis of the bypass line and / or by opening the partition wall arranged between the first vacuum cooling chamber and the second vacuum cooling chamber. This may also be true for further, adjacent vacuum cooling chambers of the vacuum cooling device. In particular, a variant would be conceivable in which no bypass line is present, but the pressure equalization takes place solely by opening the dividing wall between adjacent vacuum cooling chambers.It would be conceivable for the separating and connecting of the two adjacent vacuum cooling chambers to have the separating wall provided therebetween mounted so as to be vertically or horizontally displaceable. The partition wall is preferably in the form of a vertically or horizontally adjustable plate. This can be moved between the open and the closed position by means of a servomotor or pneumatically.By adjusting the partition wall, it is possible in particular to evacuate the vacuum cooling chambers individually, i.e. separately from one another, when the partition wall is in the closed position, and to evacuate further together after pressure equalization when the partition wall is in the open position, wherein the joint evacuation can take place during the transport of the product from one vacuum cooling chamber into the other to improve the cycle performance. Once the transfer of the product has been completed, the partition wall can be brought into the closed position and the vacuum cooling chamber accommodating the product can continue the evacuation solely up to a desired pressure level, optionally by supporting a pressure compensation used for this purpose with a vacuum cooling chamber positioned downstream and already at a relatively lower pressure level.A variant provides that the vacuum cooling device has a third vacuum cooling chamber which is arranged directly downstream of the second vacuum cooling chamber in the transport direction and can be connected to the second vacuum cooling chamber in order to produce a pressure compensation. it is thus possible to further develop the vacuum cooling process, that is to say to distribute it to three vacuum cooling chambers, in order to further cool the product passing through the vacuum cooling chambers.The products, in particular baked goods, preferably have a core temperature of below 35° C., in particular 18° C. to 25° C. Preferably, the product or the baked goods have a core temperature of at least 70° C., preferably at least 78° C., further preferably at least 85° C. at the beginning of the vacuum cooling in the vacuum cooling chamber positioned at the foremost point. 5°C, preferably mind. 10° C., preferably at least. 15° C., preferably at least. 20°C, preferably mind. 25° C., preferably at least. 30° C., preferably mind. 35° C.In particular, it is possible for the vacuum cooling device to have a fourth vacuum cooling chamber which is arranged directly downstream of the third vacuum cooling chamber in the transport direction and can be connected to the third vacuum cooling chamber for establishing a pressure compensation. The use of a plurality of vacuum cooling chambers one behind the other, wherein adjacent vacuum cooling chambers can be connected thereto by means of pressure compensation, can be extended to any desired extent in order to achieve a desired cooling capacity on the vacuum cooling device.The three or four vacuum cooling chambers can continuously carry out the vacuum cooling process in functional association in successive steps in that the respective pressure balances between the adjacent vacuum cooling chambers can assist the evacuation of that vacuum cooling chamber by the vacuum cooling chamber which follows it in the transport direction, that is to say the included pressure level of the following vacuum cooling chamber used for the pressure balance is lower than the included pressure level of the vacuum cooling chamber which precedes it. This principle can be applied to any number of vacuum cooling chambers, in particular vacuum cooling chambers positioned in series one behind the other, in order to bring the product to a desired temperature level.Preferably, the vacuum cooling chambers positioned at the foremost and / or rearmost point in the transport direction have at least one ventilation valve for producing a pressure compensation with respect to the ambient pressure. Optionally, intermediate vacuum cooling chambers need not have a venting valve. A vacuum cooling chamber positioned at the beginning can use the ventilation valve in order, in the empty state, i.e. after a further transport and trapping of the product in the vacuum cooling chamber following in the transport direction, to completely reduce the vacuum trapped therein, i.e. to adapt the pressure level to the ambient pressure of the vacuum cooling device. This allows the vented vacuum cooling chamber to be opened to receive a new product therein. An initially positioned vacuum cooling chamber can use the ventilation valve in order, in the product-loaded state, i.e. after evacuation of the volume formed individually by it to a desired pressure level, to completely reduce the vacuum enclosed therein, i.e. to adapt the pressure level to the ambient pressure of the vacuum cooling device. This vacuum cooling chamber can thus be opened to discharge the vacuum cooled product. Because venting of a product-loaded vacuum cooling chamber is necessary only at the vacuum cooling chamber positioned at the last point in the transport direction, it is possible for the product to be exposed along the cooling section only once to the pressure build-up associated with the venting, whereby the risk of damage to the product can be significantly reduced.According to one embodiment of the invention, adjacent vacuum cooling chambers in the transport direction can be evacuated jointly, in a combined arrangement and / or individually, separately from one another. For this function, the partition wall supported between the adjacent vacuum cooling chambers can be adjusted between the open position, thereby allowing the common evacuation, and the closed position, thereby allowing separate evacuation. For example, the desired vacuum may be created within the frontmost vacuum chamber to cool the product therein. Subsequently, pressure equalization is carried out between the foremost vacuum cooling chamber and the downstream vacuum cooling chamber, in which a lower pressure level than the pressure level generated in the foremost vacuum cooling chamber is included. This allows the vacuum to be further removed. After pressure equalization, the partition is moved to the open position to transport product from the forwardmost to the downstream vacuum cooling chamber. During transport, the joined vacuum cooling chambers may be evacuated together. Once the product has arrived within the subsequent vacuum cooling chamber, the partition may be closed to continue evacuation therein one at a time, thereby allowing the product to cool further. This principle can now be continued together with the vacuum cooling chamber which follows further in the transport direction. Thus, the product can be vacuum cooled by means of adjacent vacuum cooling chambers first from an individual vacuum cooling chamber, then from this in connection with a vacuum cooling chamber following in the transport direction, and then from the latter individually continuously, wherein this sequence can be further extended as desired. By the sequence of the pressure balances carried out in this case, the respective evacuation steps can be carried out in a row in such a way that a continuous pressure reduction can take place along the vacuum cooling chambers in this case.Preferably, the vacuum cooling chambers each have at least one transport belt. These may coordinate transport of the products along the vacuum cooling device. In particular, this allows the products to be transported further intermittently. For a further transport of the product from a vacuum cooling chamber into a vacuum cooling chamber adjoining the latter, the associated transport belts can be controlled synchronously with one another.A variant provides that the vacuum cooling device has at least one feed belt for the vacuum cooling chamber positioned at the foremost point in the transport direction and / or at least one discharge belt for the vacuum cooling chamber positioned at the rearmost point in the transport direction. Products can thus be transported in controlled steps into the vacuum cooling device, or products cooled therewith can be transported out of the vacuum cooling device in controlled steps.It would be conceivable for the vacuum cooling device to have at least one measuring device which is configured to record a product temperature of a product held in stock by the vacuum cooling device. For example, the measuring device, preferably a thermal imaging camera or an infrared sensor, can be configured to detect the product temperature of a product provided on the feed belt. One variant provides that the respective vacuum cooling chambers are equipped with a pressure- and / or product-temperature-detecting measuring device. It is in particular conceivable that the operation of the vacuum cooling device can be dynamically regulated on the basis of actual values detected on the basis of the measuring device or devices.It would be expedient for pressure ranges of the respective vacuum cooling chambers to be automatically adjustable on the basis of a product temperature detected outside the vacuum cooling chambers or within the vacuum cooling chambers and / or for a number of the vacuum cooling chambers participating in the vacuum cooling process to be adjustable in order to cool the product to a desired temperature therewith. For example, the last positioned vacuum cooling chamber may or may not be selectively used. Due to these dynamics, the vacuum cooling device is optimally adaptable for vacuum cooling of products treated with different heat levels.In particular, each of the vacuum cooling chambers used on the vacuum cooling device is designed to be autonomous, as regards its evacuation process. This means that the respective vacuum cooling chambers can be operated independently for evacuation. For this purpose, each vacuum cooling chamber can have its own vacuum pump, which is preferably connected to the respective vacuum cooling chamber via a valve unit. The valve unit is in particular in the form of a servo valve or proportional valve. It is thus possible for the respective vacuum cooling chambers to be evacuable independently of one another with respectively predetermined gradients.In particular, there is a packaging line equipped with a vacuum cooling device. Within the packaging line, the vacuum cooling device can be used as a stand-alone machine. Further preferably, the packaging line comprises at least one packaging machine for packaging products cooled by means of the vacuum cooling device. The vacuum cooling device and the packaging machine may be arranged one behind the other in this order in the production direction. It would be conceivable for the packaging machine to be configured in the form of a thermoform packaging machine or in the form of a tray closing machine in order to package the products cooled by means of the vacuum cooling device.Within the packaging line, the discharge belt of the vacuum cooling device can be used in particular as a feed belt of the packaging machine or for the packaging machine. It would be conceivable for the discharge belt of the vacuum cooling device to form the feed belt of a tray closing machine arranged downstream in the production direction. According to one embodiment, the discharge belt of the vacuum cooling device is used for inserting vacuum-cooled products into shell parts or deep-drawn troughs. For example, the discharge belt of the vacuum cooling device can be inserted at an insertion region of a thermoform packaging machine in order to place vacuum-cooled products in troughs provided at the insertion region.The invention further relates to a method for vacuum cooling a product along a plurality of vacuum cooling chambers positioned one behind the other in the transport direction, of which a first vacuum cooling chamber enclosing the product is evacuated to a first, predetermined pressure level which is less than an ambient pressure of the vacuum cooling chambers. Furthermore, within a second vacuum cooling chamber arranged directly downstream of the first vacuum cooling chamber in the transport direction, either a second pressure level that is lower than the first pressure level of the first vacuum cooling chamber is generated, or a second pressure level that corresponds at most to the ambient pressure is included. According to the invention, the first vacuum cooling chamber and the second vacuum cooling chamber are connected to one another for establishing a pressure compensation of the first pressure level and the second pressure level. It is thus possible to use the energy already used within one of the two vacuum cooling chambers for generating a desired pressure level at least partially on the basis of the pressure compensation when generating a vacuum in the other vacuum cooling chamber. In particular, a vacuum cooling chamber preceding in the transport direction benefits from the applied energy by the pressure compensation in order to generate a desired pressure level in a vacuum cooling chamber following in the transport direction, the internal pressure of which is lower than the generated or present internal pressure of the preceding vacuum cooling chamber. This principle can be used on any number of vacuum cooling chambers positioned one behind the other. In particular, a vacuum cooling chamber downstream in the transport direction benefits from the applied energy by the pressure compensation in order to generate a desired pressure level in a vacuum cooling chamber preceding in the transport direction, the internal pressure of which is lower than the generated or present internal pressure of the downstream vacuum cooling chamber. This applies at least to the vacuum cooling chambers which are not positioned at the first or last location.Preferably, a bypass line formed between the vacuum cooling chambers is opened for establishing the pressure compensation. The pressure equalization can be carried out via a valve unit used in the bypass line. For example, a servo valve or a proportional control valve can be used within the bypass line.For a product transfer between the vacuum cooling chambers, it can be provided that a separating wall positioned between the vacuum cooling chambers is moved from a closed position, in which it separates the two vacuum cooling chambers from one another, into an open position, whereby the two vacuum cooling chambers are joined together, so that the product can be transported from the one vacuum cooling chamber into the vacuum cooling chamber positioned behind it in the transport direction. By closing the partition wall, adjacent vacuum cooling chambers are separated and by opening the partition wall, the two vacuum cooling chambers are joined together to form a common chamber volume.In particular, it is possible for adjacent vacuum cooling chambers in the transport direction to be evacuated jointly, in a joint and / or individually, separately from one another. For example, a vacuum cooling chamber is first individually evacuated with a product enclosed therein to a desired pressure level to cool the product. Subsequently, pressure equalization is carried out with the vacuum cooling chamber downstream in the transport direction, as a result of which the pressure level generated by the preceding vacuum cooling chamber falls further on account of the internal pressure enclosed in this vacuum cooling chamber. After pressure equalization, the partition wall supported in the closed position to the subsequent vacuum cooling chamber is adjusted to the open position to transport the product into the subsequent vacuum cooling chamber. During transport, the combined chamber volume is evacuated further, in particular by a joint operation of vacuum pumps of the two combined vacuum cooling chambers. The pressure level can thus be lowered further. As soon as the two vacuum cooling chambers are separated from one another again, the preceding vacuum cooling chamber can be used for pressure equalization with a vacuum cooling chamber preceding it, wherein the internal pressure enclosed therein is used by this pressure equalization for reducing the internal pressure in the vacuum cooling chamber preceding it, while the internal pressure rises therein itself.It would be conceivable for the respective vacuum cooling chambers to be provided for a specific pressure range. In particular, the vacuum cooling chamber downstream in the transport direction can connect to the final pressure reached of the vacuum cooling chamber preceding in the transport direction and can further reduce the pressure level. The final pressure reached by the vacuum cooling chamber preceding in the transport direction is in particular obtained by a joint evacuation of this vacuum cooling chamber with a vacuum cooling chamber adjacent upstream in the transport direction when these two vacuum cooling chambers are joined together.For example, a pressure range from ambient pressure (generally approximately 1000 mbar) to 750 mbar is generated on the basis of a vacuum cooling chamber positioned at the foremost point in the transport direction, the subsequent vacuum cooling chamber generates a pressure range from 750 mbar to 500 mbar, wherein this sequential evacuation can be extended further until a predetermined target pressure is reached by a specific number of vacuum cooling chambers.In particular, the product is transported intermittently through the vacuum cooling device, wherein the product is evacuated to a specific pressure level with a defined gradient in each of the vacuum cooling chambers used therein. It would be conceivable that during vacuum cooling of a product within one of the vacuum cooling chambers, for example within the vacuum cooling chamber positioned at the foremost point, during evacuation a flow of evacuated air is regulated taking into account a comparison of an actual pressure gradient determined on the basis of actual pressure values detected within the vacuum cooling chamber with a vacuum setpoint pressure gradient of a predefined pressure profile at least from an adjustable starting pressure until an adjustable final vacuum pressure is reached within this vacuum cooling chamber. An advantageous variant provides that the pressure equalization between adjacent vacuum cooling chambers and / or a joint evacuation of adjacent, joined vacuum cooling chambers is regulated taking into account a desired gradient, in order in particular to implement a further pressure reduction in a gentle manner.It would be expedient if, during venting of the vacuum cooling chamber positioned at the rearmost point in the transport direction, a throughflow of venting air for breaking down the vacuum is regulated taking into account a comparison of an actual pressure gradient determined on the basis of actual pressure values detected within this vacuum cooling chamber with a predetermined venting setpoint pressure gradient at least from an reached, adjustable final vacuum pressure within this vacuum cooling chamber until an adjustable venting pressure is reached within this vacuum cooling chamber.For a use of the method within a packaging line, it would be advantageous if the respective vacuum cooling chambers are controlled in such a way that their vacuum cooling steps take approximately the same length of time, coordinated with one another. For example, it would be conceivable for the respective vacuum cooling steps to take place on the vacuum cooling device according to a machine operating cycle of a packaging machine used in the packaging line.According to one variant, it is provided that during the evacuation of an individual vacuum cooling chamber or during the evacuation of joined vacuum cooling chambers, the flow rate of evacuated air is regulated, in particular taking into account a predefined vacuum setpoint pressure gradient that tends to become smaller, in such a way that a vapor mass flow and / or vapor volume flow generated thereby remains constant at least temporarily during the evacuation. This enables a particularly gentle removal of water vapor from the products, so that they are not damaged.The vacuum cooling along a plurality of vacuum cooling chambers could be carried out, for example, as follows:a product to be cooled is first transported into the vacuum cooling chamber positioned at the foremost point in the transport direction. This vacuum cooling chamber is then evacuated to a specific pressure level with a defined gradient. During this first cooling step, a vapor mass flow generated in this case can be regulated constantly at least temporarily during the evacuation.When the desired pressure level within the front vacuum cooling chamber is reached, it is checked whether the vacuum cooling chamber which follows in the transport direction and is closed at an even lower internal pressure is free or empty, i.e. no product is present therein. If this is also the case, a pressure equalization is carried out between the vacuum cooling chamber positioned at the foremost point and the vacuum cooling chamber positioned behind it. The pressure level of the front vacuum cooling chamber can thus be lowered further.Next, after pressure equalization, a partition is opened between the two vacuum cooling chambers in order to transport the product further, i.e. to pass it from the front vacuum cooling chamber to the vacuum cooling chamber positioned behind it. During the further transport, both vacuum cooling chambers which are joined together by opening the partition wall can be evacuated together at least temporarily, as a result of which the internal pressure which results from pressure compensation therein can be further reduced.When the product has arrived in the subsequent vacuum cooling chamber by the further transport, the partition wall to the preceding, foremost vacuum cooling chamber is closed again. The preceding, foremost vacuum cooling chamber may then be vented before a new product is received therein. If this vacuum cooling chamber should not be the vacuum cooling chamber located at the foremost point, but rather a vacuum cooling chamber mounted further downstream in the transport direction, the pressure level enclosed therein can be used for pressure compensation with a further preceding vacuum cooling chamber in order to reduce the pressure level therein. In other words, then, no venting to ambient pressure of the vacuum cooling chamber needs to take place.According to one embodiment, it is provided that, depending on the time required for a respective vacuum cooling step within a vacuum cooling chamber and with regard to the time for the further transport of the product from one vacuum cooling chamber into the subsequent vacuum cooling chamber, there is at least one idle operating cycle along the vacuum cooling process. This can be realized, for example, by a structure in which at least three vacuum cooling chambers are positioned one behind the other.The respective vacuum cooling chambers can be individually brought to a predetermined pressure level by means of vacuum pumps which can be regulated independently of one another. Adjacent vacuum cooling chambers can be evacuated together with their vacuum pumps.The vacuum cooling chamber positioned at the last point in the transport direction can be aerated to ambient pressure in particular with a defined gradient before the last partition wall is opened and the product is transported away via an outlet-side transport belt, optionally fed to a packaging machine.Exemplary embodiments of the invention are explained in more detail with reference to the following figures. The following are shown: FIG. 1 shows a vacuum cooling device in a schematic illustration in a side view, FIGS. 2A-2J show an exemplary operation of the vacuum cooling apparatus shown in FIG. 1, FIG. 3 shows an exemplary pressure profile of a vacuum cooling chamber of the vacuum cooling device, FIG. 4 shows a three-chamber embodiment of a vacuum cooling device, FIG. 5 shows a two-chamber embodiment of a vacuum cooling device, and FIG. 6 shows a packaging machine in schematic representation.Identical technical features are provided with the same reference numerals throughout the figures.FIG. 1 shows a vacuum cooling device 1. this vacuum cooling device 1 has a total of four vacuum cooling chambers A - D formed one behind the other in the transport direction T. The respective vacuum cooling chambers A - D are formed by a chamber lower part 2, a chamber upper part 3 and partition walls 4 mounted so as to be displaceable therebetween. The separating walls 4 are each mounted so as to be adjustable between an open position 5 and a closed position 6. In FIG. 1, the middle partition 4 between the vacuum cooling chamber B and the vacuum cooling chamber C positioned behind it is shown in the open position 5. The other partitions 4 are in the closed position 6 according to FIG. 1.The vacuum cooling chambers A - D of Fig. 1 are provided for a certain pressure range, respectively. According to FIG. 1, for example, the vacuum cooling chamber A positioned at the foremost point in the transport direction T can be provided for a pressure range from ambient pressure (generally approximately 1000 mbar) to 750 mbar. A vacuum pump 7 is used for this purpose. The vacuum cooling chamber B positioned immediately behind it in the transport direction T can be provided for a pressure range between 750 mbar and 500 mbar. A vacuum pump 8 is used for this purpose. The vacuum cooling chamber C following the vacuum cooling chamber B in the transport direction T is provided for a pressure range between 500 mbar and 250 mbar and is connected for this purpose to a vacuum pump 9. The vacuum cooling chamber D, which is mounted at the last point in the transport direction T, is connected to a vacuum pump 10 and is provided for a pressure range between 250 mbar and 50 mbar.In the illustration shown in FIG. 1, in which the middle partition 4 is in the open position 5, the two vacuum cooling chambers B and C are joined together. In this situation, it is possible for the associated vacuum pumps 8, 9 to generate a vacuum together, at least until the products P located in the vacuum cooling chamber B are transported further into the vacuum cooling chamber C positioned behind it. The vacuum generated jointly by the two vacuum pumps 8, 9 is schematically represented by the dashed line 11.Further, the vacuum cooling apparatus 1 shown in FIG. 1 has a supply belt 12 for supplying products P to the vacuum cooling chambers A - D. Behind the vacuum cooling chamber D positioned at the last position in the transport direction T, a discharge belt 13 is provided in order to transport away products P cooled along the vacuum cooling device 1. It would be conceivable for the discharge belt 13 to be used to transfer the cooled product P to a packaging machine (see FIG. 6 ) positioned downstream in the transport direction T.The vacuum pumps 7- 10 shown in FIG. 1 can be operated individually and in combination of two vacuum pumps 7- 10 of adjacent vacuum cooling chambers A- D. More specifically, the respective vacuum pumps 7 - 10 of FIG. 1 are connected to the associated vacuum cooling chambers A - D via respective valve units 14 - 17. The valve units 14- 17 can each be designed as proportional control valves or servo valves in order to control a flow volume flow of water vapor during evacuation of the respective vacuum cooling chambers A- D, for example in order to keep it constant at least temporarily during evacuation. For this purpose, the respective valve units 14- 17 can be integrated as control elements within a control circuit device 18. The control circuit device 18 is configured to dynamically control the associated valve units 14- 17 with respect to a predefined setpoint gradient on the basis of detected actual pressure values within the respective vacuum cooling chambers A- D in order in particular to keep a vapor mass flow or vapor volume flow from the respective vacuum cooling chambers A- D constant when products P are vacuum-cooled therein.Product transport along vacuum cooling chambers A-D is coordinated by transport belts 19-22 as shown in Figure 1. A transport belt speed of adjacent transport belts 19- 22 can be synchronized for the further transport of products P from a vacuum cooling chamber A- D positioned behind it.Figs. 2A to 2J show a preferred operation of the vacuum cooling apparatus 1 shown in Fig. 1.Referring to Fig. 2A, the product P is enclosed in the vacuum cooling chamber B. The adjacent partition walls 4 are each mounted in the closed position 6 for this purpose. In this position, the vacuum cooling chamber B can now be evacuated from an initial pressure of 750 mbar to 500 mbar in order to vacuum cool the product P.According to FIG. 2B, pressure equalization K takes place between the vacuum cooling chamber B and the vacuum cooling chamber C via a bypass line 23, which connects the vacuum cooling chamber B to the vacuum cooling chamber C. Because a pressure level lower than 500 mbar is already present in the vacuum cooling chamber C, the pressure level generated in the vacuum cooling chamber B falls further, as a result of which the cooling of the product P is continued passively, i.e. without operation of the vacuum pump 8.As soon as the pressure equalization K schematically illustrated in FIG. 2B is finished, that is to say the same pressure level prevails within the adjacent vacuum cooling chambers B, C, for example an internal pressure at the level of 300 mbar, and provided that the vacuum cooling chamber C is empty, the dividing wall 4 positioned between the vacuum cooling chamber B and the vacuum cooling chamber C is adjusted from the closed position 6 shown in FIG. 2B into the open position 5 shown in FIG. 2C. As a result, the adjacent vacuum cooling chambers B, C are joined together and form a common chamber volume. This is shown in FIG. 2C.FIG. 2C schematically shows that the respective conveyor belts 20, 21 of the vacuum cooling chambers B, C are synchronously driven in order to transport the product P from the vacuum cooling chamber B into the vacuum cooling chamber C.During the transport of the product P from the vacuum cooling chamber B into the vacuum cooling chamber C, the two vacuum pumps 8, 9 can together further evacuate the combined chamber volume in order to further cool the product P during the further transport. As soon as the product according to FIG. 2D has arrived in the vacuum cooling chamber C, the partition 4 present between the vacuum cooling chambers B, C can be brought from the open position 5 back into the closed position 6. This is shown in FIG. 2E.Next, as shown in FIG. 2F, the vacuum cooling chamber C may be further evacuated individually. Subsequently, in particular, a pressure equalization K' with the vacuum cooling chamber D positioned behind it can take place in order to further cool the product P. Further, FIG. 2F shows that the vacuum cooling chamber A is evacuated to a desired pressure level.FIG. 2G shows a pressure equalization K" between the evacuated vacuum cooling chambers A, B, so that the pressure level within the vacuum cooling chamber A can be reduced passively, i.e. without pump operation, to the lower pressure level of the subsequent vacuum cooling chamber B.After pressure equalization K" between the vacuum cooling chambers A, B, the vacuum cooling chamber A is joined to the vacuum cooling chamber B, provided that the vacuum cooling chamber B is free, for which purpose the dividing wall 4 present between these vacuum cooling chambers A, B is brought into the open position 5 according to FIG. 2H in order to transport the product P into the vacuum cooling chamber B. During the transport of the products P from the vacuum cooling chamber A into the subsequent vacuum cooling chamber B, both can be evacuated together.According to FIG. 2I, the product P already cooled in the vacuum cooling chamber A is now enclosed in the vacuum cooling chamber B positioned behind it. The vacuum cooling chamber B can now be evacuated again to the pressure level predetermined in the vacuum cooling chamber B. Once this is achieved, the process starts anew by carrying out the pressure equalization K between the vacuum cooling chamber B and the vacuum cooling chamber C positioned behind it, as shown in FIG. 2J.An exemplary pressure pattern of one of the vacuum cooling chambers A-D is shown in FIG. 3. This can be, for example, the pressure curve of the vacuum cooling chamber B. This is evacuated with a product P enclosed therein or with a plurality of products P enclosed therein from an initial pressure level which, according to FIG. 3, is 750 mbar, to a target pressure of the order of 500 mbar, whereby the product P enclosed therein cools down. When the target pressure is reached at a level of 500 mbar, the vacuum pump 8 is shut off and, according to FIG. 3, pressure equalization K takes place with the subsequent vacuum cooling chamber C.Because the downstream vacuum cooling chamber C encloses a pressure lower than 500 mbar, the pressure level in the vacuum cooling chamber B falls further as a result of the pressure equalization K.After pressure equalization K and provided that products P are no longer enclosed in the subsequent vacuum cooling chamber C, i.e. they are free, the separating wall 4 closed between the vacuum cooling chamber B and the vacuum cooling chamber C is opened. Thereby, the vacuum cooling chambers B, C are joined together to further transport the product P from the vacuum cooling chamber B into the vacuum cooling chamber C. For this purpose, the conveyor belts 20, 21 are controlled synchronously with one another.During the further transport of the product P, the pressure level falls further, since, according to FIG. 3, the vacuum pumps 8, 9 assigned to the vacuum cooling chambers B, C are operated jointly. Once the product P has completely arrived in the vacuum cooling chamber C, the partition 4 is brought into the closed position 6. The vacuum cooling chamber C can then optionally be further evacuated individually in order to further cool the product.By closing the partition 4 after the product P is transported further into the vacuum cooling chamber C, the empty vacuum cooling chamber B is evacuated to a final pressure level which is marked by the lowest point E in FIG. 3. In order to assist the vacuum cooling chamber A preceding the vacuum cooling chamber B in evacuating a subsequent product P enclosed therein, i.e. to perform this in an energy-efficient manner, a pressure equalization K" takes place next between the vacuum cooling chambers A, B, whereby the pressure level in the vacuum cooling chamber B rises from the final pressure E to a pressure level, but does not reach the ambient pressure in the process.According to FIG. 3, the pressure equalization K'' produces a pressure X in the vacuum cooling chamber B of approximately 850 mbar. After the pressure compensation K" has been carried out between the vacuum cooling chambers A, B, the partition wall 4 lying therebetween is brought from the closed position 6 into an open position 5 in order that products P enclosed in the vacuum cooling chamber A can be transported further into the vacuum cooling chamber B. During further transport, the vacuum pumps 7, 8 are operated together in order to reduce the pressure X resulting from the pressure equalization K". According to FIG. 3, a pressure is hereby achieved in the vacuum cooling chamber B which corresponds to the starting pressure at a level of 750 mbar. Once the products P have arrived in the vacuum cooling chamber B, the products P enclosed therein may undergo a new vacuum cooling process cycle.FIG. 4 shows a vacuum cooling device 1' which, compared with the vacuum cooling device 1 shown in FIG. 1, has only three vacuum cooling chambers A, B, C. This is therefore of more compact dimensions than the vacuum cooling device 1, but can also be used, in each case between adjacent vacuum cooling chambers A-C, by means of pressure compensation K, K", in an energy-efficient and gentle manner for the vacuum cooling of products P transported therein.FIG. 5 shows a further vacuum cooling device 1". This is configured to be further reduced in installation space compared to the vacuum cooling devices 1, 1' shown in FIGS. 1 and 4, respectively. The vacuum cooling device 1" merely comprises two vacuum cooling chambers A, B, which can be used by pressure equalization K" in an energy-efficient manner and in a gentle manner for the vacuum cooling of products P transported therein.FIG. 6 shows a packaging machine 25 configured in the form of a thermoform packaging machine 30. the thermoform packaging machine 30 comprises a forming station 31 for producing thermoform troughs M in a bottom film U unwound at the beginning of the thermoform packaging machine 30. In the production direction R, downstream of the forming station 31, there is an insertion section 32 for inserting products P into the produced troughs M. The troughs M produced in the bottom film U can be transported along the insertion section 32 by means of transport chains. Downstream of the insertion section 32 in the production direction R, a sealing station 33 is arranged in order to seal the troughs M filled with product P with an upper film O. Further downstream of the sealing station 33, a transverse cutting device 35 and a longitudinal cutting device 36 are arranged one behind the other in order to cut individual packages from the film composite.A vacuum cooling device 1, 1', 1" can be positioned in the region of the insertion section 32 of the thermoform packaging machine 30 in order to feed vacuum-cooled products P therein along the insertion section 32 to the produced troughs M.

Claims

Vacuum cooling device (1, 1', 1"), comprising at least one first vacuum cooling chamber (A) which, in a closed state, can be evacuated to a first pressure level which is lower than an ambient pressure of the vacuum cooling device (1, 1', 1"), for the purpose of vacuum cooling a product (P) accommodated therein, and at least one second vacuum cooling chamber (B) which is arranged directly downstream of the first vacuum cooling chamber (A) in the transport direction (T) and within which, in the closed state, either a second pressure level which is lower than the first pressure level of the first vacuum cooling chamber (A) can be generated or within which a second pressure level which corresponds at most to the ambient pressure of the vacuum cooling device (1, 1', 1") is enclosed, characterized in that the first vacuum cooling chamber (A) and the second vacuum cooling chamber (B) for producing a pressure compensation (K, k', k") of the first pressure level and of the second pressure level can be connected to one another.Vacuum cooling device according to Claim 1, characterized in that the first vacuum cooling chamber (A) and the second vacuum cooling chamber (B) are connected by means of a bypass line (23) which can be controlled in order to produce the pressure compensation (K, K', K").Vacuum cooling device according to claim 1 or 2, characterised in that between the first vacuum cooling chamber (A) and the second vacuum cooling chamber (B) a partition wall (4) is arranged, which is displaceably mounted between a closed position (6), in which the vacuum cooling chambers (A - D) are separated from one another, and an open position (5), in which the vacuum cooling chambers (A - D) are joined together for a transport of the product (P) from the first into the second vacuum cooling chamber (B).Vacuum cooling device according to one of the preceding claims, characterized in that the vacuum cooling device (1, 1', 1") has a third vacuum cooling chamber (C) which is arranged directly downstream of the second vacuum cooling chamber (B) in the transport direction (T) and can be connected to the second vacuum cooling chamber (B) for establishing a pressure compensation (K, K', K").Vacuum cooling device according to Claim 4, characterized in that the vacuum cooling device (1, 1', 1") has a fourth vacuum cooling chamber (D) which is arranged directly downstream of the third vacuum cooling chamber (C) in the transport direction (T) and can be connected to the third vacuum cooling chamber (C) for establishing a pressure compensation (K, K', K").Vacuum cooling device according to one of the preceding claims, characterized in that the vacuum cooling chambers (A - D) positioned at the foremost and / or rearmost point in the transport direction (T) have at least one ventilation valve for producing a pressure compensation (K, K', K") with respect to the ambient pressure.Vacuum cooling device according to one of the preceding claims, characterized in that vacuum cooling chambers (A - D) adjacent in the transport direction (T) can be evacuated jointly, in a combined arrangement and / or individually, separately from one another.Vacuum cooling device according to one of the preceding claims, characterized in that the vacuum cooling chambers (A - D) each have at least one conveyor belt (19 - 22).Vacuum cooling device according to one of the preceding claims, characterized in that the vacuum cooling device (1, 1', 1") has at least one feed belt (12) for the vacuum cooling chamber (A - D) positioned at the foremost point in the transport direction (T) and / or at least one discharge belt (13) for the vacuum cooling chamber (A - D) positioned at the rearmost point in the transport direction (T).Packaging line having a vacuum cooling device (1, 1', 1") according to one of the preceding claims and having a packaging machine (25), which is positioned downstream in the production direction (R), for packaging products (P) cooled by means of the vacuum cooling device (1).Method for vacuum cooling a product (P) along a plurality of vacuum cooling chambers (A - D) positioned one behind the other in the transport direction (T), wherein a first vacuum cooling chamber (A) enclosing the product (P) is evacuated from said vacuum cooling chambers to a predetermined first pressure level which is lower than an ambient pressure of the vacuum cooling chambers (A - D), and wherein within a second vacuum cooling chamber (B) arranged directly downstream of the first vacuum cooling chamber (A) in the transport direction (T), either a second pressure level which is lower than the first pressure level of the first vacuum cooling chamber (A) or a second pressure level which corresponds at most to the ambient pressure is enclosed, characterized in that, connecting the first vacuum cooling chamber (A) and the second vacuum cooling chamber (B) to one another for establishing a pressure compensation (K, K', K") of the first pressure level and of the second pressure level.Method according to Claim 11, characterized in that, in order to produce the pressure compensation (K, K', K"), a bypass line (23) formed between the vacuum cooling chambers (A - D) is opened.Method according to Claim 11 or 12, characterized in that a dividing wall (4) positioned between the vacuum cooling chambers (A - D) is moved from a closed position (6), in which it separates the two vacuum cooling chambers (A - D) from one another, into an open position (5), as a result of which the two vacuum cooling chambers (A - D) are joined together, with the result that the product (P) can be transported from the one vacuum cooling chamber (A - D) into the vacuum cooling chamber (A - D) positioned downstream thereof in the transport direction (T).Method according to claim 13, characterised in that adjacent vacuum cooling chambers (A - D) in the transport direction (T) are evacuated jointly, together and / or individually, separately from one another.Method according to claim 14, characterised in that vacuum-cooled products (P) are supplied along the vacuum cooling chambers (A - D) to a packaging machine (25) for a packaging process taking place thereon.

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