Device and method for the vacuum cooling of products

Abstract

The invention relates to a device (3) having at least one vacuum cooling station (3a, 3b, 3c), comprising a controller (17), at least one vacuum cooling chamber (14a, 14b, 14c) for enclosing at least one product (13) accommodated therein, at least one pressure sensor (23a, 23b, 23c) connected to the controller (17) for detecting an actual pressure present within the vacuum cooling chamber (3a, 3b, 3c), a vacuum pump (20) connected to the vacuum cooling chamber (3a, 3b, 3c) for creating a vacuum within the vacuum cooling chamber (3a, 3b, 3c), and at least one valve unit (22a, 22b, 22c) which can be controlled by means of the controller (17) and via which the vacuum pump (20) is connected to the vacuum cooling chamber (3a, 3b, 3c), wherein the controller (17) is designed to determine a manipulated variable for the valve unit (22a, 22b, 22c), said determination being carried out during an evacuation of the vacuum cooling chamber (3a, 3b, 3c) taking into account a comparison of an actual pressure gradient, ascertained by the controller (17) on the basis of actual pressure values detected by means of the pressure sensor (23a, 23b, 23c), with a vacuum target pressure gradient (S1, S2, S3) of a pressure curve specified in the controller (17), on the basis of which manipulated variable the valve unit (22a, 22b, 22c) can be controlled as of a settable vacuum pressure (P1) until a settable final value pressure (P2) within the vacuum cooling chamber (3a, 3b, 3c) has been reached.

Description

[0001] Device and method for vacuum cooling of products

[0002] The present invention relates to a device for vacuum cooling products according to claim 1. Furthermore, the present invention relates to a method for vacuum cooling products according to claim 12.

[0003] DE29607689U1 discloses a thermoforming packaging machine with a sealing station, to which a mechanical cooling device is downstream in the production direction, which uses cooling pads mounted on it to press down on sealed packaging from above and below in order to cool it downstream of the sealing station after the sealing process.

[0004] JPS57-1021A discloses a thermoforming packaging machine with a forming station positioned in the production direction for producing thermoforming trays, a sealing station for producing packaging, and a vacuum station positioned between the forming station and the sealing station to remove moisture from enclosed products, thereby cooling them.

[0005] US2004 / 0105927A1 discloses a thermoforming packaging machine with a pasteurization station positioned upstream of a sealing station in the production direction of the thermoforming packaging machine. Products arriving at the pasteurization station can be heat-treated by means of steam. Optionally, a vacuum cooling process takes place following the pasteurization process.

[0006] DE102020201284A1 discloses a thermoforming packaging machine with a vacuum cooling station positioned along a filling line of the thermoforming packaging machine to cool the products placed in trays in successive steps by means of a generated vacuum before a sealing process.

[0007] When hot products, such as baked goods or precooked foods like Maultaschen (a type of German filled pasta), are vacuum-cooled, water vapor is produced within the product because the water bound in the product boils below its saturation vapor pressure. A side effect of this evaporation is the cooling of the product, as the energy required for the water to undergo a phase transition is drawn from the product. This sudden release of gas can damage the product's interior and / or its outer casing. Similarly, when a vacuum chamber is subsequently vented, products that have been pre-cooled by vacuum generation, especially those with internal cavities such as puff pastry like croissants, can be damaged by the external venting pressure, particularly a sudden increase in pressure.

[0008] The invention is based on the objective of providing a device and a method for the effective and, above all, gentle vacuum cooling of products. This objective is achieved by means of a device according to claim 1. Furthermore, this objective is achieved by means of a vacuum cooling method according to claim 12.

[0009] Advantageous further developments of the invention are given by the respective subject matter of the dependent claims.

[0010] The invention relates to a device with at least one vacuum cooling station, comprising a control unit, at least one vacuum cooling chamber for enclosing at least one product contained therein, at least one pressure sensor connected to the control unit for detecting an actual pressure present within the vacuum cooling chamber, a vacuum pump connected to the vacuum cooling chamber for generating a vacuum within the vacuum cooling chamber, and at least one valve unit controllable by means of the control unit, via which the vacuum pump is connected to the vacuum cooling chamber.According to the invention, the control system is configured to determine a manipulated variable for the valve unit during the evacuation of the vacuum cooling chamber. This manipulated variable compares the actual pressure gradient (determined by the control system based on actual pressure values ​​acquired by the pressure sensor) with the vacuum setpoint pressure gradient of a pressure profile predefined in the control system. Based on this manipulated variable, the valve unit can be controlled from an adjustable output pressure until an adjustable final vacuum pressure is reached within the vacuum cooling chamber. The control system's comparison of the vacuum setpoint pressure gradient (reference variable) with the actual pressure gradient (controlled variable) determined based on the fed-back, measured actual pressure values ​​may, if necessary, lead to...This leads to a control deviation, based on which the control system, in particular a controller integrated therein, dynamically adjusts the manipulated variable for the evacuation process in order to dynamically influence the evacuation process via the valve unit in such a way that a desired evacuation pressure profile can be specifically achieved. Based on the control principle according to the invention, the evacuation process can be specifically influenced depending on the product to be cooled and the predetermined vacuum setpoint pressure gradient or the desired vacuum pressure profile, in order to carry it out effectively and gently, specific to the product. Above all, the invention makes it possible to actively control the amount of water vapor extracted from the product during evacuation, taking into account a decrease in product temperature during evacuation, by dynamically adjusting the manipulated variable.

[0011] The term "device" can refer to a packaging machine or a workstation for a packaging machine. It can also refer to a production line or multiple production lines, each belonging to a production plant. Therefore, a device can also refer to the entire production plant. Depending on the system boundaries of the device, the vacuum pump may be a component of the device, for example, as part of a workstation, a component of a packaging machine, a component of a production line or lines, or a component of the entire production plant. Depending on the system boundaries of the device, the vacuum pump may be used as a vacuum source for a single packaging machine or as a central vacuum source for several packaging machines.

[0012] Preferably, the control system is configured to determine a manipulated variable for the valve unit during the venting of the vacuum cooling chamber. This manipulated variable compares the actual pressure gradient (determined by the control system based on actual pressure values ​​acquired by the pressure sensor) with the venting target pressure gradient of a pressure profile predefined in the control system. Based on this manipulated variable, the valve unit can be regulated, at least temporarily, from the reached final vacuum pressure until an adjustable venting pressure is reached, preferably corresponding to the initial pressure of the preceding evacuation process. In this variant, the setpoint-actual value comparison of the venting target pressure gradient (reference variable) with the actual pressure gradient (controlled variable) determined based on the fed-back, measured actual pressure values, performed by the control system during venting, may lead to...This leads to a control deviation, based on which the control system, in particular a controller integrated within it, dynamically adjusts the manipulated variable for the aeration process. Using this manipulated variable, the valve unit dynamically influences the aeration process in such a way that a desired aeration pressure profile can be precisely achieved. This allows the aeration process to be specifically influenced depending on the product to be cooled and the predetermined target aeration pressure gradient or desired aeration pressure profile, ensuring product-specific, effective, and gentle aeration. Above all, this variant makes it possible to actively control the forces exerted on the product by the aeration pressure during aeration by dynamically adjusting the valve setting, thus preventing product damage.

[0013] One variant provides that the device includes at least one further vacuum cooling station downstream of the vacuum cooling station, with a vacuum cooling chamber in which evacuation can be dynamically controlled from at least an adjustable vacuum pressure, preferably corresponding to the adjustable ultimate vacuum pressure achieved at the preceding vacuum cooling station, until another adjustable ultimate vacuum pressure is reached, based on a comparison of the setpoint and actual pressure gradients performed during evacuation. In the further vacuum cooling station, controlled vacuum cooling of the product can be carried out according to the control principle of the preceding vacuum cooling station. The vacuum setpoint pressure gradient used as a reference variable for this can differ, at least temporarily, from the vacuum setpoint pressure gradient stored in the control system for controlled evacuation in the preceding vacuum cooling station.It is advantageous if, within the vacuum cooling chamber of the subsequent vacuum cooling station, venting can be dynamically controlled, at least temporarily, from the point at which the adjustable ultimate vacuum pressure is reached until an adjustable venting pressure is reached, preferably corresponding to the initial pressure, based on a comparison of the setpoint and actual pressure gradients performed during venting. In the subsequent vacuum cooling station, the controlled venting of the product can be carried out according to the control principle of the preceding vacuum cooling station. The setpoint pressure gradient used as a reference variable for venting can differ, at least temporarily, from the setpoint pressure gradient stored in the control system for controlled venting in the preceding vacuum cooling station.

[0014] An advantageous variant provides that at the vacuum cooling station, evacuation can be carried out at maximum power, at least temporarily, particularly until the initial pressure is reached, and / or at the other vacuum cooling station, evacuation can be carried out at maximum power, at least temporarily, particularly from the initial pressure until the adjustable vacuum pressure is reached. The control system can thus initiate the evacuation process at least at one or more of the respective vacuum cooling stations at the beginning of the evacuation process during a predetermined interval at maximum vacuum power, in order to establish a suitable vacuum for (further) vacuum cooling within the respective vacuum chamber(s) as quickly as possible. This results in a particularly economical cooling process that can be carried out in short intervals.In this variant, the evacuation interval combines an initial, unregulated vacuum process section to reach the initial pressure within the cooling chamber as quickly as possible, with a subsequent, regulated vacuum process section to cool the product as gently as possible by removing water vapor.

[0015] One practical approach provides that at the vacuum cooling station, venting can be carried out at maximum power, at least temporarily, particularly from a preset, measured actual pressure value until the final pressure is reached, and / or at the subsequent vacuum cooling station, venting can be carried out at maximum power, at least temporarily, particularly from a preset, measured actual pressure value corresponding to the final vacuum pressure reached at the preceding vacuum cooling station. The control system can, in particular, initially control the venting process at at least one or more of the respective vacuum cooling stations, taking into account a target venting pressure gradient, and then subsequently operate at maximum venting power for a predetermined interval to return to the final pressure level as quickly as possible.This results in a particularly economical ventilation process that can be carried out in short intervals. In this variant, the ventilation interval combines an initial, controlled ventilation phase to reduce the vacuum as gently as possible for the products inside the cooling chamber, with a subsequent, uncontrolled ventilation phase to reach a pressure level suitable for opening the vacuum cooling chamber as quickly as possible, especially the initial pressure level.

[0016] In particular, controlled vacuum cooling at a vacuum cooling station can begin at a measured actual pressure value that corresponds to the ultimate vacuum pressure of a preceding vacuum cooling station or that is slightly higher, for example, by at least 1%, and in particular by 5%, and / or controlled vacuum cooling at a vacuum cooling station can continue down to a measured actual pressure value that corresponds to the adjustable vacuum pressure of the subsequent vacuum cooling station, from which controlled evacuation takes place there, or that is slightly lower, for example, by at least 1%, and in particular by 5%, than this. This allows controlled cooling to continue essentially seamlessly from station to station.Until the point at which controlled, gentle evacuation begins at the respective vacuum cooling stations, uncontrolled evacuation, i.e. with maximum vacuum power, can take place in order to build up the vacuum required for continued cooling as quickly as possible in the respective vacuum chambers, starting from a respective initial pressure, in particular from an ambient pressure of the vacuum chambers.

[0017] According to one embodiment, it is provided that at successive vacuum cooling stations in the production direction, the evacuation intervals controlled therein tend to become shorter and / or the ventilation intervals controlled therein tend to become longer in order to cool the products passed through them in successive steps to a desired temperature level.

[0018] One variant proposes that, at successive vacuum cooling stations in the production direction, the unregulated evacuation intervals tend to become longer and / or the unregulated ventilation intervals tend to become shorter in order to cool the products passing through them to a desired temperature level in successive steps.

[0019] Preferably, the respective valve unit for dynamic evacuation and / or dynamic venting comprises at least one adjustable throttle, a proportional valve, and / or a servo valve. This allows the flow cross-section to be varied in order to control the evacuation and / or venting with respect to their respective control variables. Preferably, the valve unit includes separate, controllable valves for evacuation and venting, in particular separate proportional valves and / or servo valves.

[0020] It would be advantageous if the valve unit had at least one valve that could be switched in parallel with the throttle, proportional valve, and / or servo valve for unregulated, maximum evacuation and / or ventilation capacity. This valve could be opened to accelerate evacuation and / or ventilation, particularly in addition to the throttle, proportional valve, and / or servo valve.

[0021] It is conceivable that the device is part of a feeding system configured as a cooling line for a packaging machine, or that it is configured as an integral part of a packaging machine, particularly a thermoforming packaging machine. Such a thermoforming packaging machine has, in particular, several vacuum cooling stations positioned one after the other along an infeed line in the production direction, configured for intermittent vacuum cooling, taking into account the machine's cycle time. Advantageously, the evacuation pressure values ​​at the vacuum cooling stations are set such that each station performs approximately equal work cycles, especially for evacuation and venting, as this allows for maximum machine output.

[0022] An advantageous variant provides that the valve unit, particularly considering a decreasing vacuum-setpoint pressure gradient, is at least temporarily adjustable during evacuation to maintain a constant steam mass flow or steam volume flow. This counteracts the increasing water vapor loss that accompanies decreasing pressure. This facilitates particularly gentle evacuation. A practical variant provides that the valve unit, particularly considering a decreasing venting-setpoint pressure gradient, is at least temporarily adjustable during venting to maintain constant forces generated by pressure build-up. This prevents damage to the chilled products during venting.

[0023] One variant provides that the control system contains specific vacuum target pressure gradients and / or ventilation target pressure gradients for different products, especially for products at different temperatures, which can be activated at one or more vacuum cooling stations as control variables for controlled evacuation and / or ventilation.

[0024] It would be advantageous for the device to include at least one temperature sensing unit functionally connected to the control system, such as a thermal imaging camera or an infrared thermometer. This unit could be integrated into the vacuum cooling station to record the product temperature before, during, and / or after evacuation and / or ventilation. Based on this data, or on the average product temperature of several products placed in the vacuum cooling station, the respective control parameters at the vacuum cooling station and / or at the downstream vacuum cooling station could be preset and / or dynamically adjusted.

[0025] Preferably, at least one filter unit is provided between the vacuum pump and the vacuum cooling chamber for filtering air extracted from the vacuum cooling chamber by evacuating it and / or for filtering air supplied to the vacuum cooling chamber by venting it. The filter unit can be arranged upstream of the valve unit in the direction of airflow, whether evacuated or supplied. This ensures hygienic operation.

[0026] According to one embodiment, the device has at least one condenser for separating water vapor extracted from the products. The condenser is positioned upstream of the vacuum pump, in particular to prevent the vacuum pump from drawing in water vapor. It would be conceivable for each vacuum cooling station to include its own condenser. Preferably, the condenser's capacity is variable, and in particular, functionally linked to the product temperature of the products being cooled.

[0027] The device can be used on a packaging machine, in particular a thermoforming packaging machine. A sealing station can be positioned on the packaging machine downstream of the vacuum cooling device in the production direction. Within this sealing station, evacuation can be dynamically controlled, at least from an adjustable vacuum pressure (preferably corresponding to the adjustable final vacuum pressure achieved at the upstream vacuum cooling station) until a final vacuum pressure adjustable for the sealing station is reached, based on a target / actual pressure gradient comparison performed during evacuation.

[0028] Preferably, following evacuation, a gassing process can be carried out at the sealing station to create a desired atmosphere inside sealed packages. Subsequently, the packages received in the sealing station can be sealed. Finally, the sealing station is ventilated so that it can be opened for further transport of the packages.

[0029] Furthermore, the invention relates to a method for vacuum cooling products. According to the invention, at a vacuum cooling station, during the evacuation of a vacuum cooling chamber containing the products, the flow of evacuated air is regulated by comparing an actual pressure gradient determined on the basis of actual pressure values ​​recorded within the vacuum cooling chamber with a target vacuum pressure gradient of a predetermined pressure profile, at least from an adjustable initial pressure until an adjustable final vacuum pressure is reached within the vacuum cooling chamber.

[0030] A preferred variant provides that during ventilation of the vacuum cooling chamber containing the products, the flow of ventilating air is regulated by comparing an actual pressure gradient determined on the basis of actual pressure values ​​recorded within the vacuum cooling chamber with a predetermined ventilation target pressure gradient, at least from an reached, adjustable final vacuum pressure until an adjustable ventilation pressure is reached within the vacuum cooling chamber.Preferably, the products are vacuum-cooled at least at a further vacuum cooling station in a further vacuum cooling chamber provided therein, by regulating the flow of evacuated air during an evacuation process taking place therein, taking into account a comparison of an actual pressure gradient determined on the basis of actual pressure values ​​recorded within the further vacuum cooling chamber with a predetermined target vacuum pressure gradient, at least from an adjustable vacuum pressure, which preferably corresponds to the adjustable final vacuum pressure achieved within the preceding vacuum cooling chamber, until an adjustable further final vacuum pressure is reached.

[0031] It would be advantageous if, during the ventilation of the further vacuum cooling chamber containing the products, the flow of ventilating air were regulated, taking into account a comparison of an actual pressure gradient determined on the basis of actual pressure values ​​recorded within the vacuum cooling chamber with a predetermined ventilation target pressure gradient, at least from the reached, adjustable further final vacuum pressure until an adjustable ventilation pressure is reached within the further vacuum cooling chamber.

[0032] An advantageous embodiment provides that the respective final vacuum pressure values ​​at the respective vacuum cooling stations are set in such a way that evacuation and venting at the respective vacuum cooling stations take approximately the same amount of time.

[0033] It would be advantageous if, during evacuation, the flow of evacuated air, especially taking into account a predetermined, decreasing vacuum-set pressure gradient, were regulated in such a way that a resulting steam mass flow or steam volume flow remains constant, at least temporarily, during evacuation.

[0034] A method for stepwise vacuum cooling of products can proceed along a packaging machine, in particular along an intermittently operating thermoforming packaging machine, as follows:

[0035] • Enclosing hot products in a vacuum cooling chamber of a vacuum cooling station positioned at the front of the production line,

[0036] • If necessary, uncontrolled evacuation of the vacuum cooling chamber with maximum vacuum cross-section up to an adjustable vacuum pressure,

[0037] • Controlled evacuation of the vacuum cooling chamber down to a specific, adjustable final vacuum pressure,

[0038] Ventilation, preferably at least temporarily controlled ventilation of the vacuum cooling chamber, • Opening the vacuum cooling chamber and transporting the cooled products in the production direction to a downstream positioned vacuum cooling chamber of another vacuum cooling station,

[0039] • Enclosing the pre-cooled products in the further vacuum cooling chamber,

[0040] • Unregulated evacuation of the further vacuum cooling chamber with maximum vacuum cross-section up to an adjustable vacuum pressure, which preferably corresponds to the final vacuum pressure of the preceding vacuum cooling station, or is slightly higher, in particular a maximum of 50 mbar, preferably a maximum of 100 mbar, preferably a maximum of 150 mbar,

[0041] • Controlled evacuation down to a specific, adjustable final vacuum pressure,

[0042] • Ventilation, preferably at least temporarily controlled ventilation of the further vacuum cooling chamber,

[0043] • Opening the further vacuum cooling chamber and transporting the cooled products in the production direction into a downstream positioned process chamber of a sealing station of the packaging machine for the production of sealed packages,

[0044] • Unregulated evacuation of the process chamber with maximum vacuum cross-section up to an adjustable vacuum pressure, which preferably corresponds to or is slightly higher than the final vacuum pressure of the preceding vacuum cooling station, in particular a maximum of 50 mbar, preferably a maximum of 100 mbar, preferably a maximum of 150 mbar,

[0045] • If necessary, controlled evacuation down to a specific, adjustable final vacuum pressure,

[0046] • Fumigation of the packages placed in the process chamber,

[0047] • Sealing the fumigated packages, and

[0048] Ventilation of the process chamber to open the sealing station for further transport of the sealed packages. For the process described above, additional vacuum cooling stations with controlled vacuum cooling can be used to ensure that the products are cooled to a predetermined temperature level before being received in the sealing station.

[0049] The products, especially baked goods, preferably have a core temperature of less than 35°C after vacuum cooling, particularly between 18°C ​​and 25°C. Preferably, the product or baked goods have a core temperature of at least 70°C at the start of vacuum cooling in the vacuum cooling chamber, more preferably at least 78°C, and further preferably at least 85°C.

[0050] The products can be cooled by at least 5°C, preferably at least 10°C, preferably at least 15°C, preferably at least 20°C, preferably at least 25°C, preferably at least 30°C, preferably at least 35°C, particularly during vacuum cooling.

[0051] Exemplary embodiments of the invention are explained in more detail with reference to the following figures. They show:

[0052] Figure 1 shows a packaging machine in the form of a thermoforming packaging machine in a schematic side view.

[0053] Figure 2 shows a step-by-step vacuum cooling process along the deep-drawing packaging machine from Figure 1, and

[0054] Figure 3 shows a further step-by-step vacuum cooling process on the thermoforming packaging machine from Figure 1.

[0055] Technical features are consistently identified in the figures using the same reference symbols.

[0056] Figure 1 shows a packaging machine 100 configured as an intermittently operating thermoforming packaging machine 1. The thermoforming packaging machine 1 comprises a forming station 2, a device 3 with three vacuum cooling stations 3a, 3b, 3c, a sealing station 4, a cross-cutting unit 5, and a longitudinal cutting unit 6, arranged in this order along a transport direction R on a machine frame 7. At the inlet side of the machine frame 7 is a feed roller 8 from which a bottom film 9 is unwound. Furthermore, the thermoforming packaging machine 1 has a transport chain 10 that grips the bottom film 9 and transports it along the transport direction R for each main work cycle.

[0057] As shown in Figure 1, the forming station 2 is designed as a deep-drawing station in which cavities 11 are formed in the base film 9 by deep drawing, for example, using compressed air and / or vacuum. The forming station 2 can be configured such that several cavities 11 are formed side by side in the direction perpendicular to the transport direction R. Downstream of the forming station 2 in the transport direction R, a loading section 12 is provided, along which the cavities 11 formed in the base film 9 are filled with products 13. Vacuum cooling chambers 14a, 14b, 14c are provided at the respective vacuum cooling stations 3a, 3b, 3c, which are arranged one after the other in the transport direction R, in order to gradually cool the products 13 transported into them to a desired temperature level by means of a vacuum created therein.

[0058] The sealing station 4 has a hermetically sealable chamber 4a in which the atmosphere in the recesses 11 can be evacuated and / or replaced by gas purging with a replacement gas or with a gas mixture immediately before sealing with a top film 16 dispensed from a top film receiver 15.

[0059] The cross-cutting device 5 can be designed as a punch that cuts the bottom film 9 and the top film 16 in a direction transverse to the transport direction R between adjacent troughs 11. The cross-cutting device 5 operates in such a way that the bottom film 9 is not cut across its entire width, so that at least in one edge region the bottom film 9 remains intact. This enables controlled onward transport through the transport chain 10.

[0060] The longitudinal cutting device 6 can be designed as a knife arrangement with which the lower film 9 and the upper film 16 are cut between adjacent recesses 11 and at the lateral edge of the lower film 9 in the transport direction R, so that individual packages V are present behind the longitudinal cutting device 6.

[0061] The thermoforming packaging machine 1 also has a control unit 17. Its function is to control and monitor the processes taking place at the workstations in the thermoforming packaging machine 1. A display device 18 with operating elements 19 serves to visualize and / or influence the process sequences in the thermoforming packaging machine 1 for or by an operator.

[0062] Figure 1 shows that the vacuum cooling stations 3a, 3b, 3c are positioned directly upstream of the sealing station 4 in the transport direction R, so that the work cycle can be directly conveyed from the last vacuum cooling station 3c in the transport direction R into the sealing chamber 4a of the sealing station 4 by a feed movement. Alternatively, it is conceivable that the vacuum cooling stations 3a, 3b, 3c are positioned together at a further forward position along the filling section 12 in the transport direction R, i.e., offset further towards the forming station 2, so that the vacuum cooling station 3c, positioned last in the transport direction R, is spaced apart from the sealing station 4.

[0063] The number of vacuum cooling stations 3a, 3b, 3c depends on the desired vacuum cooling result and can therefore vary. Instead of the three vacuum cooling stations 3a, 3b, 3c shown in Figure 1, it would be conceivable to provide only two or even more than three vacuum cooling stations 3a, 3b, 3c to gradually cool the products 13 transported into them. Figure 1 further shows that the respective vacuum cooling stations 3a, 3b, 3c and the downstream sealing station 4 are connected to a vacuum pump 20 used by these workstations. Alternatively, the sealing station 4 could be operated by means of a separate vacuum pump.

[0064] The vacuum cooling chambers 14a, 14b, 14c are connected to the vacuum pump 20 via pressure lines 21. Each of the pressure lines 21 connecting the vacuum pump 20 to the vacuum cooling chambers 14a, 14b, 14c is equipped with a valve unit 22a, 22b, 22c to at least temporarily control the evacuation and, if applicable, ventilation processes taking place in the vacuum cooling chambers 14a, 14b, 14c, in order to dynamically control, in particular, the removal of water vapor from the products. Pressure sensors 23a, 23b, 23c are installed in the respective vacuum cooling chambers 14a, 14b, 14c to detect the actual pressure present in each of these chambers.

[0065] Furthermore, Figure 1 shows a temperature sensing unit 24. The temperature sensing unit 24 is designed to detect the product temperature T of the products 13. In Figure 1, the temperature sensing unit 24 is shown as a unit positioned outside the vacuum cooling chambers 14a, 14b, 14c. Alternatively, it would be conceivable that the temperature sensing unit 24 is integrated within the vacuum cooling chamber 14a, which is positioned first in the transport direction R. According to another embodiment, each of the vacuum cooling chambers 14a, 14b, 14c has its own temperature sensing unit 24. The product temperature values ​​T detected by the temperature sensing unit(s) 24 can be used as actual values ​​for dynamically controlled vacuum cooling along the vacuum cooling stations 3a, 3b, 3c.For example, taking into account the product temperature T measured outside or inside the vacuum cooling chambers 14a, 14b, 14c, at least one predetermined pressure profile with a target gradient can be determined as a control variable for the dynamic control of the associated vacuum cooling processes.

[0066] Figure 1 further shows that the vacuum pump 20 is connected to the sealing chamber 4a via another pressure line 25. A valve unit 26 is provided in this additional pressure line 25. For pressure detection in the sealing chamber 4a, this unit includes a pressure sensor 27. Based on the actual pressure values ​​detected by the sensor in the sealing chamber 4a, the valve unit 26 can be controlled to carry out a regulated gas exchange within the sealing chamber 4a prior to the sealing process.

[0067] The control unit 17 shown in Figure 1 can dynamically control a control variable for the respective valve unit 22a, 22b, 22c during the evacuation of the vacuum cooling chambers 14a, 14b, 14c, taking into account a respective comparison of an actual pressure gradient determined by the control unit 17 on the basis of actual pressure values ​​detected by the respective pressure sensors 23a, 23b, 23c with a vacuum target pressure gradient of a pressure profile specified in the control unit 17, wherein in particular a pressure profile determinable on the basis of the product temperature T, from an adjustable output pressure until an adjustable final vacuum pressure is reached within the respective vacuum cooling chamber 14a, 14b, 14c.

[0068] Figure 2 shows a vacuum pressure profile carried out stepwise, at least temporarily during the individual evacuation steps, along three vacuum cooling stations 3a, 3b, 3c, dynamically controlled.

[0069] At the beginning of the vacuum cooling process according to Figure 2 (not shown in Figure 2), the vacuum cooling station 3a, located at the front in the transport direction R, can be evacuated from a pressure value Pi, with a maximum cross-section of the valve unit 22a, up to an adjustable pressure value. This is done to quickly build up a pressure level within the vacuum cooling station 3a, allowing water vapor to be extracted from the product for cooling. The pressure value Pi can subsequently correspond to an initial pressure PA, in particular atmospheric pressure, at which the respective vacuum cooling stations 3a, 3b, 3c can be opened for further transport of the troughs 11.

[0070] In Figure 2, the evacuation of the closed vacuum cooling station 3a is dynamically controlled, starting from the pressure value Pi and taking into account a predetermined, constant vacuum setpoint pressure gradient Si, down to a specific, adjustable final vacuum pressure P2, which is lower than the pressure value Pi. During the dynamically controlled evacuation, the product 13 enclosed in the vacuum cooling station 3a is cooled by the controlled removal of water vapor. This is achieved by comparing the actual pressure gradient (determined based on the recorded actual pressure values) with the vacuum setpoint pressure gradient Si. This is accomplished by controlling the valve unit 23a using a control variable resulting from this comparison, in order to regulate the water vapor removal as the pressure level continuously decreases.Instead of the constant vacuum-set pressure gradient Si specified as a guide variable in Figure 2, the vacuum-set pressure gradient Si can in particular be chosen such that a constant volume flow of water vapor is extracted from the product 13 during evacuation.

[0071] After evacuation in the vacuum cooling station 3a, i.e., once the final vacuum pressure P2 is reached, the vacuum cooling station 3a is vented so that the pressure build-up allows it to open for a feed movement of the product 13. As shown in Figure 2, from the final vacuum pressure P2 to the outlet pressure PA, venting is controlled according to a preset, constant venting target pressure gradient Bi. This prevents an uncontrolled pressure build-up in the vacuum cooling chamber 14a of the vacuum cooling station 3a, and in particular avoids a sudden pressure increase that could damage the product 13. As shown in Figure 2, constant vacuum and venting target pressure gradients Si and Bi, respectively, are used for the controlled evacuation and venting of the vacuum cooling station 3a. However, this is only an example.Alternatively, at least one of these gradients could also have a curved shape; for example, the vacuum target pressure gradient Si could be chosen as a reference variable such that it tends to decrease during its progression from pressure value Pi to the final vacuum pressure value P2, and / or the maintained venting target pressure gradient Pi tends to increase during its progression from the final vacuum pressure value P2 to the outlet pressure PA. This results in product-friendly pressure profiles at the end of evacuation and / or at the beginning of venting.

[0072] After the vacuum cooling step in vacuum cooling station 3a, the already vacuum-cooled product 13 moves further along the transport direction R into vacuum cooling station 3b for further cooling. As shown in Figure 2, in vacuum cooling station 3b, the product is initially evacuated unregulated with the maximum cross-section of the connected valve unit 22b until an adjustable pressure value Pu is reached. This pressure value essentially corresponds to the final vacuum pressure value P2 from the upstream vacuum cooling station 3a, or is slightly higher, for example, by approximately 5%. This allows vacuum cooling station 3b to be evacuated as quickly as possible to a pressure level at which the vacuum cooling of product 13 can be continued. Due to the time saved by this maximum evacuation at the beginning of the process, the product 13 remains cool for a longer period.Due to the reduced time consumption, taking into account the machine work cycle, sufficient time remains for the subsequent control to be carried out precisely with regard to the machine work cycle.

[0073] It is conceivable that the pressure value Pu corresponds to a maximum of 50 mbar. By evacuating unregulated, i.e., with maximum cross-section up to the pressure value Pu, the vacuum cooling chamber 14b of the vacuum cooling station 3b can regulate the subsequent cooling process of the product 13 at an early stage. This occurs by dynamically controlling the evacuation of the vacuum cooling station 3b from the pressure value Pu onwards, taking into account a further vacuum-setpoint pressure gradient S2, in order to further cool the product 13 according to a desired cooling process step. This cooling process step, controlled by the vacuum-setpoint pressure gradient S2, is carried out down to a predetermined, adjustable pressure value PG, which is lower than the pressure value Pu. The pressure values ​​Pu and PG are always lower than in the preceding vacuum cooling stations if further vacuum cooling process steps follow, in order to cool the product 13 step by step from an initial temperature level to a desired temperature level.

[0074] Following controlled evacuation based on the target vacuum pressure gradient S2 in vacuum cooling station 3b, which can be less than, greater than, or equal to the target vacuum pressure gradient Si of vacuum station 3a, venting takes place in vacuum cooling station 3b. From the pressure value PG, i.e., from a final vacuum pressure value set in vacuum cooling station 3b, to the outlet pressure PA, venting can be controlled according to a preset target venting pressure gradient B2 to release the product as gently as possible for further transport to the subsequent vacuum cooling station 3c.

[0075] Once the output pressure PA is reached, the vacuum cooling station 3b can be opened to transport the product 13, which has now cooled further, to the vacuum cooling station 3c positioned downstream.

[0076] The vacuum cooling station 3c can initially be evacuated unregulated with maximum cross-section from the initial pressure PA to an adjustable pressure value P5 in order to quickly enclose the product 13 within the vacuum cooling station 3c at a pressure level from which the vacuum cooling process step for further cooling of the product 13 can be carried out, in accordance with the preceding vacuum cooling steps. The pressure value P5 is equal to or slightly higher than the pressure value PG, preferably a maximum of 50 mbar.

[0077] Following the uncontrolled evacuation, controlled evacuation is carried out from pressure value P5 down to a specific, adjustable final vacuum pressure Pe, which is lower than pressure value P5, taking into account a vacuum-set pressure gradient S3, in order to further cool product 13. From the final vacuum pressure Pe, the vacuum cooling station 3c is vented. This can be controlled, as shown in Figure 2, by means of the venting set pressure gradient B3 shown therein, up to the outlet pressure PA.

[0078] Figure 2 suggests that the vacuum cooling station 3c, positioned furthest in the transport direction R, can be configured as a sealing station 4, meaning that the vacuum cooling process step taking place therein can be carried out as a preliminary step to subsequent gassing, sealing, and venting of the sealing chamber 4a. In other words, it would be conceivable that the vacuum cooling stations 3a, 3b, and the sealing station 4 could be jointly controlled for vacuum cooling of the product 13 through functional integration.

[0079] Figure 3 shows a different vacuum pressure profile compared to Figure 2. In particular, Figure 3 shows that the target vacuum pressure gradients Si, S2, S3 are not constant, but rather tend to decrease. According to this design, the respective target vacuum pressure gradients Si, S2, S3 are thus defined as control variables such that the resulting steam mass flows or steam volume flows can be controlled at a constant level during the respective vacuum cooling process steps along the vacuum cooling stations 3a, 3b, 3c. In other words, the water vapor removal can be kept constant during the respective vacuum cooling process steps in the vacuum cooling stations 3a, 3b, 3c in order to cool the product 13 to be cooled as gently as possible to a desired temperature level step by step.Furthermore, Figure 3 shows that the respective aeration process steps are carried out using aeration target pressure gradients Bi, B2, B3, which tend to increase until the initial pressure PA is reached, in order to carry out aeration that is gentle on the product 13 at least at the beginning of the respective aeration steps.

Claims

Claims 1. Device (3) with at least one vacuum cooling station (3a, 3b, 3c), comprising a control unit (17), at least one vacuum cooling chamber (14a, 14b, 14c) for enclosing at least one product (13) contained therein, at least one pressure sensor (23a, 23b, 23c) connected to the control unit (17) for detecting an actual pressure present within the vacuum cooling chamber (14a, 14b, 14c), a vacuum pump (20) connected to the vacuum cooling chamber (14a, 14b, 14c) for generating a vacuum within the vacuum cooling chamber (14a, 14b, 14c), and at least one valve unit (22a, 22b, 22c) controllable by means of the control unit (17), via which the vacuum pump (20) is connected to the vacuum cooling chamber (14a, 14b, 14c), characterized in that the control unit (17) is designed to, during an evacuation of the vacuum cooling chamber (14a, 14b, 14c) taking into account a comparison of a based on the pressure sensor (23a, 23b,23c) The actual pressure gradient determined by the controller (17) is used to determine a control variable for the valve unit (22a, 22b, 22c) based on the actual pressure values ​​recorded by the controller (17) and a vacuum-setpoint pressure gradient (Si, S2, S3) of a pressure profile specified in the controller (17). This control variable allows the valve unit (22a, 22b, 22c) to be controlled from an adjustable vacuum pressure (Pi) up to the point of reaching an adjustable final vacuum pressure (P2) within the vacuum cooling chamber (14a, 14b, 14c).

2. Device according to claim 1, characterized in that the control unit (17) is configured to determine a control variable for the valve unit (22a, 22b, 22c) during the venting of the vacuum cooling chamber (14a, 14b, 14c), taking into account a comparison of an actual pressure gradient determined by the control unit (17) on the basis of actual pressure values ​​detected by means of the pressure sensor (23a, 23b, 23c) with a venting target pressure gradient (Bi, B2) of a pressure profile specified in the control unit (17), on the basis of which the valve unit (22a, 22b, 22c) can be controlled at least temporarily from the reached final vacuum pressure (P2) until an adjustable venting pressure, which preferably corresponds to an output pressure (PA), is reached.

3. Device according to claim 1 or 2, characterized in that the device (3) has at least one further vacuum cooling station (3a, 3b, 3c) downstream of the vacuum cooling station (3a, 3b, 3c) with a vacuum cooling chamber (14a, 14b, 14c) within which evacuation can take place at least from an adjustable vacuum pressure (Pu), which preferably corresponds to the adjustable vacuum pressure achieved at the preceding vacuum cooling station (3a, 3b, 3c). The final vacuum pressure (P2) corresponds to a further adjustable final vacuum pressure (PG) which can be dynamically controlled until an adjustable pressure gradient comparison is reached, based on a target / actual pressure gradient comparison carried out during evacuation.

4. Device according to claim 3, characterized in that within the vacuum cooling chamber (14a, 14b, 14c) of the further vacuum cooling station (3a, 3b, 3c) ventilation is dynamically controllable from reaching the adjustable further ultimate vacuum pressure (PG) at least temporarily until reaching an adjustable further ventilation pressure, which preferably corresponds to the output pressure (PA), on the basis of a target-actual pressure gradient comparison carried out during ventilation.

5. Device according to one of the preceding claims, characterized in that at the vacuum cooling station (3a, 3b, 3c) evacuation can be carried out at least temporarily, in particular until the adjustable vacuum pressure (Pi) of the vacuum cooling chamber (14a, 14b, 14c) is reached, without regulation and at maximum power, and / or at the further vacuum cooling station (3a, 3b, 3c) evacuation can be carried out at least temporarily, in particular from the output pressure (PA) until the adjustable vacuum pressure (Pu) is reached, without regulation and at maximum power.

6. Device according to one of the preceding claims, characterized in that the valve unit (22a, 22b, 22c) for dynamic evacuation and / or ventilation comprises at least one adjustable throttle, a proportional valve, and / or a servo valve.

7. Device according to claim 6, characterized in that the valve unit (22a, 22b, 22c) has at least one valve switchable in parallel to the throttle, proportional valve and / or servo valve for an unregulated, maximum evacuation and / or ventilation capacity.

8. Device according to one of the preceding claims, characterized in that the device (3) is part of a feed device configured as a cooling line for a packaging machine (100), or is an integral part of a packaging machine (100), which is configured in particular in the form of a thermoforming packaging machine (1).

9. Device according to one of the preceding claims, characterized in that the valve unit (22a, 22b, 22c) is controllable at least temporarily during evacuation to maintain a constant steam mass flow or steam volume flow.

10. Packaging machine with a device according to one of claims 1 to 9, characterized in that a sealing station (4) is positioned on the packaging machine (100) downstream of the device (3) in the production direction (R), within which evacuation is dynamically controllable at least from an adjustable vacuum pressure (Ps), which preferably corresponds to the adjustable final vacuum pressure (PG) achieved at the vacuum cooling station (3a, 3b, 3c) preceding it, until reaching a final vacuum pressure (Pe) adjustable for the sealing station, based on a target-actual pressure gradient comparison carried out during evacuation.

11. Packaging machine according to claim 10, characterized in that a gassing process can be carried out at the sealing station (4) following evacuation to produce a desired atmosphere inside sealed packagings (V).

12. Method for vacuum cooling of products (13), characterized in that at a vacuum cooling station (3a, 3b, 3c) during the evacuation of a vacuum cooling chamber (14a, 14b, 14c) holding the products (13), a flow of evacuated air is controlled by comparing an actual pressure gradient determined on the basis of actual pressure values ​​recorded within the vacuum cooling chamber (14a, 14b, 14c) with a vacuum target pressure gradient (Si, S2, S3) of a predetermined pressure profile at least from an adjustable vacuum pressure (Pi) until an adjustable final vacuum pressure (P2) is reached within the vacuum cooling chamber (14a, 14b, 14c).

13. Method according to claim 12, characterized in that during ventilation of the vacuum cooling chamber (14a, 14b, 14c) receiving the products (13), a flow of ventilating air is controlled by comparing an actual pressure gradient determined on the basis of actual pressure values ​​recorded within the vacuum cooling chamber (14a, 14b, 14c) with a ventilation target pressure gradient (Bi, B2) of a predetermined pressure profile at least from the reached, adjustable final vacuum pressure (P2) until an adjustable ventilation pressure is reached within the vacuum cooling chamber (14a, 14b, 14c).

14. Method according to claim 12 or 13, characterized in that the products (13) are vacuum-cooled at least at a further vacuum cooling station (3a, 3b, 3c) in a further vacuum cooling chamber (14a, 14b, 14c) provided therein, by measuring a flow of evacuated air during an evacuation process taking place therein, taking into account a comparison of an actual pressure gradient determined on the basis of actual pressure values ​​recorded within the further vacuum cooling chamber (14a, 14b, 14c) with a vacuum target pressure gradient (Si, S2, S3) of a predetermined pressure profile is regulated at least from an adjustable vacuum pressure (Pu), which preferably corresponds to the adjustable final vacuum pressure (P2) reached within the preceding vacuum cooling chamber (14a, 14b, 14c), until an adjustable further final vacuum pressure (PG) is reached.

15. Method according to claim 14, characterized in that during ventilation of the further vacuum cooling chamber (14a, 14b, 14c) receiving the products (13), a flow of ventilating air is controlled by comparing an actual pressure gradient determined on the basis of actual pressure values ​​recorded within the vacuum cooling chamber (14a, 14b, 14c) with a ventilation target pressure gradient (Bi, B2) of a predetermined pressure profile at least from the reached, adjustable further final vacuum pressure (PG) until an adjustable ventilation pressure is reached within the further vacuum cooling chamber (14a, 14b, 14c).

16. Method according to one of claims 12 to 15, characterized in that the respective final vacuum pressure values ​​(P2, PG, Pe) at the respective vacuum cooling stations (3a, 3b, 3c) are set such that the evacuation and venting at the respective vacuum cooling stations (3a, 3b, 3c) take approximately the same amount of time.

17. Method according to one of claims 12 to 16, characterized in that during evacuation the flow of evacuated air is regulated taking into account a predetermined, tending to decrease vacuum target pressure gradient (S1, S2, S3) such that a steam mass flow or steam volume flow generated thereby remains constant at least temporarily during evacuation.

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