Comminuting machine, and method for comminuting a product while feeding a fluid

Abstract

The invention relates to a comminuting machine (1) for comminuting a product, said comminuting machine comprising: a cutting device (4) for comminuting the product, which device has at least two cutting units (7a-c); a drive shaft (5) for driving the cutting units (7a-c); and a housing (3) in which the cutting units (7a-c) are arranged one behind the other along the longitudinal axis (L) of the drive shaft (5). The comminuting machine (1) is designed to feed a fluid in the form of a liquid gas into at least one intermediate space (11a, 11b) which is formed in the housing (3) between two cutting units (7a, 7b; 7c, 7d) that are adjacent to one another along the longitudinal axis (L) of the drive shaft (5). The invention also relates to an associated method for comminuting a product.

Description

[0001] Crushing machine and method for crushing a product under

[0002] Supply of a fluid

[0003] The present invention relates to a comminution machine for comminution of a product, comprising: a cutting device for comminution of the product, which has at least two cutting sets, a drive shaft for driving the cutting sets, and a housing in which the cutting sets are arranged one behind the other along a longitudinal axis of the drive shaft. The invention also relates to a method for comminution of a product in a comminution machine, in particular in a comminution machine designed as described above, comprising: comminution of the product in a cutting device of the comminution machine, wherein the cutting device has at least two cutting sets that are arranged one behind the other in a housing along a longitudinal axis of a drive shaft and that are driven by the drive shaft.The product that is crushed in the crushing machine can, in principle, be any product to be crushed. For example, the product to be crushed could be a food product, pet food, cosmetic products (e.g., for collagen production), or a product from the chemical industry. Due to the input of mechanical drive energy, the product heats up during crushing. Therefore, there is usually a need for tempering, typically cooling, of the product. This is especially true when crushing bones or other comparatively hard products, which lead to considerable heat generation during crushing.

[0004] In shredding machines whose interior is accessible to the operator ("open systems"), such as so-called cutters, the starting product can be cooled before shredding by directly adding a cooling medium. In this case, water, ice, or dry ice can be added as a cooling medium to the starting product in a bowl if the cutter's protective hood is closed before or during shredding. Liquid gas, such as liquid nitrogen or liquid carbon dioxide (CO2), is also possible for cooling the product in a cutter (see, for example, "https: / / www.seydelmann.com / wp-content / uploads / 2015 / 05 / 150529-_-Datenblatt- Vakuum-Koch-K-754-DE.pdf").

[0005] In the case of shredding machines whose interior is not accessible to an operator, the starting product can also be cooled by adding a cooling medium, e.g. in the form of water or dry ice, before the starting product is fed into the shredding machine.

[0006] Rll 2614828 C1 describes a comminution machine having a cooling chamber in which the starting product is cooled before being fed to a comminutor. A tangential branch pipe opens into the cooling chamber, through which a cooling medium, e.g. CO2, is supplied in order to increase the ductility of the starting product before comminution. EP 2 509 428 B1 discloses a method for cooling products, in particular foodstuffs, using two cryogenic liquids, nitrogen and carbon dioxide CO2, in a cooling device which is an enclosure selected from the group comprising mixers, kneaders, or mills. The cryogenic liquids are injected into a mass of the product to be cooled in the lower region of the enclosure.A forced injection system may be arranged in the upper part of the enclosure to allow the recirculation and use of the cooling power of the cold gases resulting from the lower injection of the cryogenic liquids.

[0007] DE 20 2016 106601 U1 describes a micro-shredder comprising a cutting system for shredding food, chemical, and / or medical products, a drive shaft for driving the cutting system, and a housing in which the cutting system is arranged, which has at least one cutting set. The housing comprises a temperature control channel configured to directly control the temperature of the housing and indirectly control the temperature of food products located therein using a temperature control medium. The temperature control channel can have a plurality of interconnected temperature control bores.

[0008] Object of the invention

[0009] It is the object of the present invention to further develop a comminution machine and a method for comminution of a product in order to increase the quality of the product obtained during comminution.

[0010] Subject of the invention

[0011] This object is achieved by a comminution machine of the type mentioned at the outset, which is designed to supply a fluid, in particular a liquefied gas, into at least one intermediate space formed in the housing between two cutting sets adjacent in the longitudinal direction or along the longitudinal axis of the drive shaft. In the comminution machine according to the invention, a fluid, i.e. a liquid or a gas, is sprayed directly into the product between two adjacent cutting sets or cutting stages and distributed at high speed in a way that is gentle on the product. When a fluid in the form of a liquefied gas is used for cooling, cooling can take place directly during comminution where the heat is generated (the liquefied gas suddenly 'evaporates') and, conversely, the 'harmful' effect ('cold / freeze burn') of the cooling medium can be minimized / eliminated.In this way, cold spots, which often occur in other injection processes, are avoided and optimal heat transfer and temperature distribution are ensured.

[0012] It has been demonstrated that the supply of a liquid or gas is possible even in a closed system, i.e., between two axially adjacent cutting sets (i.e., along the longitudinal axis of the drive shaft), without critical pressures occurring that could lead to a deterioration in product quality or damage to the shredding machine. This also applies if the drive shaft, which is driven by a motor, rotates at high speeds of more than, for example, 3000 rpm.

[0013] The fluid can be used, for example, for inerting, i.e., increasing shelf life by displacing atmospheric oxygen, and / or for tempering, e.g., for cooling, the product. In particular, a liquefied gas, e.g., liquid N2 or CO2, can be supplied to the intermediate space or the product located therein for cooling. In this case, the product is cooled directly at the location where heat is generated by the comminution of the product by a respective cutting set. Cooling is therefore particularly efficient; moreover, only a small portion of the energy used for cooling is released into the environment.

[0014] The addition of gases or liquefied gases to the product also has the advantage that they can be removed from the product almost completely when it leaves the shredding machine, whereas this is not the case when liquids are added. The degassing of the product (“deareation”) can be carried out using a degassing system. An effective degassing or extraction system (degasser or demaerator) can, for example, be designed in the form of a hollow cylinder similar to a cyclone. On the inlet side of such an extraction system, a large surface area can be created by means of an “impact plate”. In this way, the “fall height” in the cylinder can be effectively used for degassing. Depending on the properties of the product, the gas can also remain bound in the product, e.g. to “foam” the product or to influence the conveying behavior of the cutting device during certain shredding processes.to improve the properties of products to be ground. The addition of a gaseous medium can be advantageous, for example, if the product tends to stick together or clump, as is the case with certain products in the chemical industry.

[0015] If the shredding machine has more than two cutting sets, the fluid can be supplied to each of the gaps. However, it is also possible for the fluid to be supplied to only one of the gaps or to two or more gaps. There are various options for supplying the fluid to each gap.

[0016] In one embodiment, the comminution machine has at least one nozzle for the fluid to exit into the intermediate space. This nozzle is formed at one end of a supply channel that preferably runs in the housing. The nozzle influences the flow of the fluid as it passes over or exits from the supply channel into the intermediate space. The supply channel is usually formed in the housing. In principle, however, it is also possible for the supply channel to be formed on another component of the comminution machine. For example, the supply channel can run in or along the drive shaft and, if necessary, in components that are connected to the drive shaft in a rotationally fixed manner.

[0017] If the supply channel runs within the housing, it typically has a first end that opens into the intermediate space at the nozzle, and a second end that opens out on the outside of the housing. At the second end, the supply channel is usually connected to a supply line for the fluid. The supply channel is preferably a single, for example radial, bore in the housing. It is also possible for a supply channel to branch out from the second end on the outside of the housing and have multiple ends at which nozzles are formed that open into the intermediate space. There is a risk that product will penetrate into the nozzles and clog them.

[0018] If multiple nozzles are provided, it has proven advantageous if they are evenly arranged in the circumferential direction. The nozzle, or more precisely the inside of the nozzle, can have a constant cross-section, but it is also possible for the nozzle cross-section to increase or decrease toward the nozzle outlet. The inside of the nozzle can, for example, be conical.

[0019] In a further development of this embodiment, the nozzle is designed for the fluid to exit essentially tangentially with respect to the longitudinal axis of the drive shaft. It has proven advantageous if the fluid flows essentially tangentially into the intermediate space. Essentially tangential means that the nozzle or its longitudinal axis is oriented at an angle between approximately 50° and approximately 130°, preferably between approximately 70° and approximately 110°, to the radial direction with respect to the longitudinal axis of the drive shaft. The nozzle can be designed or oriented to allow the fluid to exit into a plane perpendicular to the longitudinal axis of the drive shaft.

[0020] In a further development, the nozzle is oriented at a (non-zero) angle relative to a plane perpendicular to the longitudinal axis of the drive shaft. The angle can, for example, be between approximately 10° and approximately 50°. Orientation at an angle relative to the plane perpendicular to the drive shaft is particularly advantageous when one of the cutting sets has a rotating cutting head. In this case, the angle is typically selected such that the nozzle is inclined toward the rotating cutting head.

[0021] In a further development, the nozzle is designed for the fluid to exit in the direction of rotation of the drive shaft (during comminution of the product). It is advantageous if the flow direction of the fluid exiting the nozzle approximately corresponds to the flow direction of the product at the nozzle location. In particular, the fluid should have the same direction of rotation (clockwise or counterclockwise) as the drive shaft when flowing out of the nozzle.

[0022] In a further development of this embodiment, the nozzle is formed in a projection of the housing which projects into the intermediate space, wherein the projection preferably tapers radially in the direction of the longitudinal axis of the drive shaft. The projection can, for example, be designed in the manner of a finger or the like, which tapers radially towards the longitudinal axis of the drive shaft. The task of such a projection is to damming the product against rotation. This damming enhances the conveying behavior of the cutting set and reduces the temperature input. The projections or damming fingers typically form part of the cutting device anyway and, due to their geometry, are particularly well suited to introducing the fluid into the product.

[0023] In a further development, the nozzle is formed on a side of the projection facing away from the direction of rotation of the drive shaft (“leeward side”). Such an arrangement of the nozzle has proven advantageous for entraining the fluid exiting the nozzle through the product. This applies in particular when one of the cutting sets has a cutting head that is arranged in or projects into the intermediate space. In this case, a negative pressure is generated on the back of a respective rotating cutting blade of the cutting head, which promotes entraining the fluid exiting the nozzle when the fluid exits on the leeward side of the projection.

[0024] In a further development, the nozzle is arranged at a radial distance from the longitudinal axis of the drive shaft that is less than 80%, preferably less than 60%, particularly preferably less than 40% of a maximum radius of the gap in the housing. The maximum radius of the gap is understood to mean the maximum extension of the gap in the radial direction starting from the longitudinal axis of the drive shaft.

[0025] It has proven advantageous if the fluid is introduced into the gap or into the product in an area in which the pressure generated by the rotation of the product due to the centrifugal force is lower than the pressure of the supplied fluid when it exits the nozzle.

[0026] Due to components protruding into the gap or the radial extension of the drive shaft, it is generally not possible to position the nozzle directly near the longitudinal axis of the drive shaft. However, positioning the nozzle at a distance of less than 80%, possibly less than 60%, or less than 40% of the maximum radius of the gap in the housing is generally possible and usually sufficient to ensure that the pressure generated by the rotation of the product is lower than the pressure of the fluid exiting the nozzle.

[0027] The comminution machine can have at least one nozzle for the fluid to exit into the intermediate space. To ensure a uniform supply of the fluid to the product, it has proven advantageous if the fluid is supplied to one and the same intermediate space via more than one nozzle, e.g. via two, three, four or more nozzles. To ensure a homogeneous introduction of the fluid into the product, it is advantageous if the nozzles are distributed evenly over the intermediate space in the circumferential direction, i.e. if they are equidistant from one another in the circumferential direction. It is also generally advantageous if the fluid supplied to the intermediate space exits at the same pressure at each nozzle.

[0028] In a further embodiment, the comminution machine comprises at least one controllable valve for the controlled supply of fluid into the intermediate space. In the simplest case, the valve has an open and a closed switching state to release or block the fluid (liquefied gas) supply. To switch the valve, the comminution machine has a control device, e.g. in the form of a control computer, which also controls other functions of the comminution machine. The fluid is supplied to the controllable valve by means of a fluid supply, usually at a predetermined, constant or regulated pressure. When supplying carbon dioxide as liquefied gas, it is problematic that a pressure drop below the set pressure leads to the formation of snow (dry ice) and clogs the supply channel.For this purpose, the fluid is advantageously supplied to each nozzle via a separate supply channel using a controllable valve assigned to the nozzle. The controllable valve is arranged as close as possible to the respective nozzle in order to keep the flow channel between the controllable valve and the nozzle as short as possible, thus minimizing the pressure loss in the area between the valve and the nozzle. Likewise, the supply channel running within the housing should be kept as short as possible to minimize the flow pressure loss. The cross-section of the supply channel is usually larger than the outlet cross-section of the nozzle's outlet opening.

[0029] Alternatively, it is also possible for the fluid to be supplied to all nozzles assigned to a gap via a common controllable valve, or for the fluid to be supplied to all nozzles of the shredder via a single controllable valve. In this case, it is necessary to ensure that the pressure at each nozzle is high enough to reliably prevent the formation of dry ice and thus the clogging of the flow channels and nozzles by dry ice.

[0030] In other technical applications where liquid carbon dioxide is sprayed (e.g., tunnel freezers, cabinet freezers, etc.), it is also common practice to pressurize the flow channels for the fluid supply with a gaseous fluid before turning on the LPG supply, and to flush them with a gaseous fluid immediately after turning off the LPG supply to empty the piping system of all LPG residues. The gaseous fluid can be the same medium as the LPG, and this could also be applied here.

[0031] The dimensioning, i.e., the calculation of the outlet cross-section of the nozzles, must be carried out depending on the total number of nozzles, the machine's drive power, the product throughput, the liquid gas supply ratios, the required cooling capacity, and the desired product temperature at the end of the comminution process. As described above, the use of one valve per nozzle has proven advantageous. It is advisable to only begin feeding the fluid, especially a liquid gas, once the product is present in the intermediate space. The presence of product in the intermediate space can be detected, for example, by the load absorption of a motor on the drive shaft. The load absorption of the motor can be monitored to regulate the product feed, prevent the cutting heads from running dry on the die plates, and to detect malfunctions in the comminution of the product.

[0032] The supply of fluid to the product during comminution does not necessarily have to be continuous. For example, the supply of fluid can be controlled depending on the temperature of the product within the cutting device. To measure the temperature of the product, suitable sensors can be arranged, for example, upstream or downstream of the cutting device in the product flow direction. If sufficient temperature control or cooling of the end product is determined after comminution, the supply of liquid gas can, for example, be temporarily stopped, reduced, or interrupted only at individual nozzles from a multitude of nozzles. With a suitable design of the fluid supply, it may also be possible to control or adjust the amount of fluid supplied to the intermediate space per unit of time using an adjustable valve or a suitable throttling device.

[0033] In a further embodiment, at least one cutting set has a stationary perforated plate that interacts with a rotating cutting head to comminute the product. It is possible for all cutting sets of the comminution machine to have a stationary perforated plate and a rotating cutting head, but this is not absolutely necessary. The cutting set(s) of the comminution machine can also be designed in a different way; for example, the cutting set can have a stationary perforated plate that interacts with a rotating perforated plate to comminution the product, or a cutting set based on the rotor-stator principle can be used. The rotor of such a cutting set is typically arranged radially inward and surrounded by the radially outer annular stator.The rotor features knife blades that interact with the stator's cutting gaps to shred the product like a scissor cut. However, the use of a cutting set with a rotating cutting head has proven advantageous for this application, as this creates a vacuum on the back of each cutting blade or blade wing, which promotes fluid entrainment, as described above. The use of a cutting set with a stationary perforated plate has proven advantageous because the holes in the perforated plate allow for extremely fine distribution of the fluid. This allows for optimal heat transfer.

[0034] In a further development, the distance between the cutting head and the stationary perforated plate can be adjusted longitudinally or along the longitudinal axis of the drive shaft. To adjust the distance, the stationary perforated plate and / or the cutting head can be moved axially. The displacement of the stationary perforated plate in the axial direction can be achieved, for example, by moving an adjusting body, against which the stationary perforated plate(s) of the cutting set(s) are brought into contact, in the axial direction within a housing, while the shaft with the cutting head remains stationary in the axial direction. The adjusting body can, for example, be designed as a sleeve which is rotatably mounted with an external thread in a corresponding internal thread of the housing. It is also possible to move the drive shaft along its longitudinal axis to adjust the distance.In this case, the drive shaft is mounted so that it can be moved longitudinally. The axial displacement of the shaft can also occur during rotation. The distance over which the axial distance can be varied is usually a few millimeters. By reducing the distance, for example, the cutting blades of the cutting head can be brought into contact with the stationary perforated plate for resharpening if necessary.

[0035] It goes without saying that the shredding machine has additional components not described above. For example, an ejector mounted on and driven by the drive shaft is typically installed downstream of the cutting sets in the product conveying direction. The ejector serves to centrifugally accelerate the product before it is conveyed out of the shredding machine through an outlet or outlet housing. The conveying of the product can be assisted by suction from the outlet side.

[0036] A further aspect of the invention relates to a method of the type mentioned above, in which, during comminution of the product, a fluid, in particular a liquefied gas, is supplied to at least one intermediate space in the housing formed between two cutting sets adjacent along the longitudinal axis of the drive shaft. As described above, by supplying a gas or liquid directly into the product located in the intermediate space, the product can, for example, be tempered or rendered inert. It is understood that the fluid can also be supplied to the product for another purpose, for example to influence the color, consistency, rheological properties, or appearance of the product.

[0037] If the product is to be cooled with the help of the fluid, a liquefied gas, for example CO2 or N2, is preferably fed into the intermediate space for cooling. As described above, in this case the product can be cooled immediately adjacent to the cutting sets where heat is introduced into the product during comminution. Before feeding in liquefied gas, it is advantageous to first flush the feed channels serving as cooling channels with a gaseous medium in order to free them of product residues, mainly water, since water in particular can freeze suddenly on contact with the liquefied gas and block the respective feed channel. The gaseous medium and the liquefied gas can be one and the same gas, which is drawn at different pressures via two different connections from a gas reservoir, e.g. a compressed gas cylinder.

[0038] In one variant of the process, the fluid is only supplied to the gap when the presence of the product in the cutting device is detected. The presence of the product in the cutting device can be detected, for example, based on the power consumption of the drive shaft motor: If this power consumption increases or exceeds a predetermined limit, it can be assumed that the product is being shredded by the cutting device. As described above, it is not mandatory that a fluid be supplied to the product during the entire time the product is being shredded in the cutting device.

[0039] In a further variant, at least a portion of the fluid fed to the intermediate space is separated from the product in at least one intermediate space of the cutting device located downstream in the product conveying direction and / or after it exits the comminution machine. The product to be comminuted typically passes through the cutting device together with the fluid fed into the at least one intermediate space, i.e. the product and the fluid are transported further together in the same direction (product conveying direction). The (gaseous) fluid can be separated from the comminuted product after it exits the comminution machine, for example by feeding the gaseous fluid to a degassing or extraction system (degasser or deaerator) which has a collecting container for separating the comminuted product and the gaseous fluid. Alternatively, it may be possible.It is also possible to separate at least part of the gaseous fluid supplied to an intermediate space of the cutting device from the product in (at least) one downstream intermediate space of the cutting device.

[0040] In a further variant, the temperature of the comminuted product after exiting the cutting device is regulated by adjusting the feed rate of the fluid supplied to the at least one intermediate space. In this variant, the comminution machine has at least one temperature sensor or a temperature probe, which can be arranged, for example, in an outlet housing or in an outlet pipe of the comminution machine, to measure the temperature of the comminuted product. In this case, the control device of the comminution machine is designed to adjust the feed rate of the fluid supplied to the at least one intermediate space in order to regulate the measured actual temperature of the comminution product to a target temperature.

[0041] The adjustment of the amount of fluid supplied to the product to be shredded can be carried out discontinuously by completely switching individual or a series of nozzles on or off, but continuous adjustment is also possible via one or more of the controllable (adjustment) valves.

[0042] In a further variant, the liquefied gas supplied to at least one intermediate space is provided subcooled relative to its phase equilibrium pressure to avoid gas bubbles. Subcooling the liquefied gas causes it to be colder than boiling temperature, rather than in the usual boiling state. This prevents gaseous fluid from forming during the fluid flow to the nozzles. Such conditioned provision of the fluid or liquefied gas can increase the accuracy of adjusting the product temperature. It can also prevent snow formation, which could lead to blockage of the supply channel.

[0043] The product that should be cooled during comminution could, for example, be bones that are being crushed to produce gelatin for pet food or to produce collagen for cosmetics or pharmaceuticals. The product could also be rinds or similar, the temperature of which should generally not exceed approximately 30°C in order not to negatively affect their color, flavor, or viscosity (to avoid coagulation of proteins). The product could also be another food product, such as cooked sausage, etc. It is essential for all food products that their shelf life for subsequent storage and their flavor are not impaired during comminution.By adding a liquefied gas, which may in particular be a mixture of several liquefied gases, the product can be cooled or, if necessary, heated during comminution, so that this requirement can be met by means of the method according to the invention and the comminution machine according to the invention.

[0044] Further advantages of the invention will become apparent from the description and the drawings. Likewise, the above-mentioned and further listed features can be used individually or in combination. The embodiments shown and described are not intended to be exhaustive, but rather serve as examples for describing the invention.

[0045] They show:

[0046] Fig. 1 is a schematic representation of an embodiment of a comminution machine according to the invention in a longitudinal section along a drive shaft,

[0047] Fig. 2 is a schematic representation of the shredding machine of Fig. 1 in a cross-section passing through a space between two adjacent cutting sets, and

[0048] Fig. 3 is a schematic representation of a detail of the shredding machine of Fig. 1 in a longitudinal section along the drive shaft.

[0049] Fig. 1 and Fig. 2 show a shredding machine 1 which has an inlet housing 2 for feeding a product to be shredded, for example meat (sausage meat), raw materials of plant or animal origin (fish, vegetables), bones, boiled sausage, rinds, etc. Downstream of the inlet housing 2 in the conveying direction of the product is a housing 3 which houses a cutting device 4 which is mounted on a horizontally mounted shaft 5 (drive shaft) driven by a motor 5a. The cutting device 4 is used for (fine) shredding the product. Downstream of the cutting device 4 in the conveying direction is an outlet housing 6 for removing the shredded product. Unlike what is shown in Fig. 1, the motor 5a can also be attached to the inlet end of the drive shaft 5 or to the inlet housing 2.

[0050] As can be seen in Fig. 1, a first, second and third cutting set 7a, 7b, 7c is arranged in sequence starting from the inlet housing 2 along a longitudinal axis L of the drive shaft 5. In the example shown, the three cutting sets 7a, 7b, 7c each have a cutting or knife head 8a, 8b, 8c, which interacts with a stationary perforated plate 9a, 9b, 9c fastened in the housing 3 to shred the product. The first, second and third cutting heads 8a, 8b, 8c are mounted on the drive shaft 5 in a rotationally fixed manner via a positive connection, in the example shown with the aid of grooves provided on the drive shaft 5, and are driven by the latter. A respective cutting head 8a, 8b, 8c exerts a centrifugal force on the product, so that in particular accumulated foreign bodies are carried outwards in a radial direction, where they can be discharged via a discharge valve.

[0051] The cutting device 4 is completed by an ejector 10, which is mounted on the drive shaft 5. The ejector 10 serves to centrifugally accelerate the shredded product before it is removed from the shredding machine 1 via the outlet housing 6.

[0052] In the shredding machine 1 shown in Fig. 1 and Fig. 2, a first intermediate space 11a is formed in the housing 3 between the first and second cutting sets 7a, 7b and a second intermediate space 11b is formed between the second and third cutting sets 7b, 7c. In the example shown in Fig. 1 and Fig. 2, in which the cutting sets 7a-c each consist of a stationary perforated plate 9a-c and a rotating cutting head 8a-c, the first and second intermediate spaces 11a, 11b extend along the longitudinal axis L of the drive shaft 5 (X-axis of an XYZ coordinate system) between the two mutually facing sides of the stationary perforated plates 9a, 9b and 9b, 9c, respectively. The second and third cutting heads 8b, 8c protrude into the respective intermediate space 11a, 11b.

[0053] The comminution machine 1 is designed to supply a fluid to both the first intermediate space 11a and the second intermediate space 11b. For this purpose, five supply channels 12a-e for the fluid are formed in the housing 3, which extend from a radially outer side of the housing 3 into the respective intermediate space 11a, 11b, as is shown in Fig. 2 for the second intermediate space 11b. Each supply channel 12a-e has a section in the form of a radial bore that tapers radially toward the longitudinal axis L of the drive shaft 5, to which section, also designed as a bore, is connected, running tangentially with respect to the longitudinal axis L of the drive shaft 5 and forming a nozzle 13a-e for the essentially tangential exit of the fluid into the intermediate space 11b. As can also be seen from Fig. 2, each nozzle 13a-e is designed oraligned to allow the fluid to exit into the intermediate space 11a in the same direction of rotation D as the drive shaft 5 into the second intermediate space 11b (in the illustration of Fig. 2 in the direction of rotation of the respective cutting head 8a-c).

[0054] As shown in Fig. 2, the nozzle 13a-e, which forms the tangentially extending portion of the supply channel 12a-e, as well as a radially inner part of the radially extending portion of the supply channel 12a-e, is formed in a projection 14a-e of the housing 3, which projects radially into the intermediate space 11b. The projection 14a-e is finger-shaped and tapers toward the longitudinal axis L of the drive shaft 5.

[0055] Although the product partially accumulates at a respective projection 14a-e, the provision of projections 14a-e on the housing 3 is advantageous for the following reason: The fluid should be supplied to the product at a location where the pressure or force of the fluid upon exiting the respective nozzle 13a-e is greater than the centrifugal force exerted on the product by the cutting head 8c. Since the centrifugal force increases with increasing distance from the longitudinal axis L of the drive shaft 5, the fluid should be supplied close to the longitudinal axis L of the drive shaft 5.

[0056] In the example shown in Fig. 1, a respective nozzle 13a-e, or more precisely its outlet opening, is arranged at a radial distance R from the longitudinal axis L of the drive shaft 5, which is less than 80% of a maximum radius RM of the first or second intermediate space 11a, 11b in the housing 3. The distance R between the nozzle 13a-e and the longitudinal axis L of the drive shaft can also be less than 60% or possibly less than 40% of the maximum radius RM of the respective intermediate space 11a, 11b.

[0057] As can be seen in Fig. 2, the nozzle 13a-e is formed on a side 15a-e of a respective projection 14a-e facing away from the direction of rotation D of the drive shaft 5. With respect to the direction of rotation D of the third cutting head 8c, the respective nozzle 13a-e or its outlet opening is thus located on the leeward side. In this way, when the fluid exits the nozzle 13a-e, it can be exploited that a lower pressure is generated at the rear of a respective cutting blade of the cutting head 8c compared to the front of the cutting blade, and the fluid is entrained as it exits the nozzle 13a-e.

[0058] To supply the fluid into the respective intermediate space 11a, 11b, the comminution machine 1 shown as an example has five nozzles 13a-e, which are evenly distributed in the circumferential direction or arranged at equal distances from one another in the circumferential direction. In this way, a homogeneous supply of the fluid to the respective intermediate space 11a, 11b can be achieved. It is understood that more or fewer than five nozzles 13a-e can be provided to supply the fluid to the intermediate space 11a, 11b. This is due to the fact that the projections 14a-e on which the nozzles 13a-e are formed protrude radially into the intermediate space 11a, 11b.

[0059] Fig. 2 shows a controllable valve 16 which is signal-connected to a control device 17 in order to enable or prevent the supply of fluid to the second intermediate space 11b, depending on the switching state of the valve 16. The fluid is taken from a fluid reservoir (not shown) and supplied to the controllable valve 16 via a supply line. In the case of a fluid in the form of a liquefied gas, e.g. N2 or CO2, which is used to cool the product, the reservoir can be a compressed gas cylinder, for example. The fluid in the form of the liquefied gas is ideally provided in the compressed gas cylinder subcooled compared to its phase equilibrium pressure. In this way, the formation of gas bubbles in the liquefied gas and possibly the formation of snow in the supply line can be avoided.

[0060] In the example shown in Fig. 2, the controllable valve 16 controls only the supply of fluid to the first nozzle 13a. The fluid is supplied to the second to fifth nozzles 13b-e via corresponding controllable valves (not shown). Further controllable valves (not shown) serve to control the supply of fluid to the nozzles not shown in Fig. 2, which open into the first intermediate space 11a. It is understood that the nozzles 13a-e can also be assigned to the controllable valve(s) 16 in other ways.

[0061] It is advantageous if the supply of fluid to the respective spaces 11a, 11b is only activated when a sufficient amount of product is already present in the spaces 11a, 11b or in the cutting device 4. The presence of product in the cutting device 4 can be detected, for example, based on the power consumption of the motor 5a of the drive shaft 5: If the power consumption of the motor 5a exceeds a predetermined threshold value, it can be assumed that a sufficient amount of product is located in the housing 3 and is being shredded by the cutting device 4, so that a backflow of the fluid into a feeding device for feeding the shredding machine 1 with the product is avoided or excluded. The fill level of such a feeding device can also be monitored for a sufficient amount of product using suitable sensors.In the event that it can be assumed that a sufficient amount of product is present in the housing 3, the control device 17 activates the valve 16 in order to supply the fluid to the intermediate space 11a, 11b.

[0062] In the example shown, the control device 17 also serves to regulate the temperature of the shredded product after it exits the cutting device 4. For this purpose, the shredding machine 1 has a temperature sensor (not shown in the illustration), which in the example shown is arranged at a suitable location in the outlet housing 6. The actual temperature of the shredded product measured by the temperature sensor is transmitted to the control device 17. The control device 17 adjusts the supply quantity of the fluid supplied to the two intermediate spaces 11a, 11b in order to regulate the temperature of the shredded product to a desired temperature. For this purpose, the control device 17 controls the controllable valves 16 of the shredding machine 1.For this purpose, the control device 17 can effect a discontinuous adjustment of the fluid supply quantity by completely switching on or off individual or a plurality of valves 16. However, the control device 17 can also continuously adjust the fluid supply quantity by acting on one or more controllable (adjusting) valves 16, which are designed to continuously adjust the respective supply quantity. In both cases, the temperature of the comminuted product can be regulated to the desired target temperature by adjusting the fluid supply quantity.

[0063] It is advantageous if the axial distance A between the front of the respective stationary perforated plate 9a, 9b, 9c and the cutting head 8a, 8b, 8c interacting with it to shred the product - shown as an example for the first cutting set 7a - is adjustable within certain limits, since in this way the degree of shredding of the product as well as the throughput and the heat input into the product can be influenced. It can also be advantageous if the respective cutting head 8a, 8b, 8c, or more precisely its knife blades, can be brought into contact with the associated stationary perforated plate 9a, 9b, 9c during the rotational movement in order to resharpen them if necessary. For the purposes mentioned, a maximum variation of the distance A of a few millimeters, usually only one or several tenths of a millimeter, is sufficient.

[0064] In order to be able to adjust the distance A between the respective cutting head 8a, 8b, 8c and the associated perforated plate 9a, 9b, 9c, in the example shown, the drive shaft 5 is displaced in the axial direction or along its longitudinal axis L. The axial displacement of the shaft 5 can be carried out, for example, by means of a handwheel or by means of the control device 17, even during operation of the shredding machine 1, in order to set the desired distance A between the respective stationary perforated plate 9a, 9b, 9c and the associated cutting head 8a, 8b, 8c. As an alternative to the axial displacement of the shaft 5, the distance A can also be achieved by displacing the perforated plates 9a, 9b, 9c relative to the housing 3 and to a drive shaft that is stationary in the axial direction, as is described, for example, in DE 19960409 A1. As shown in Fig.As can be seen in Figure 3 with the third nozzle 13c, the nozzles 13a-e are aligned at an angle a to the YZ plane, which runs perpendicular to the longitudinal axis L of the drive shaft 5. The angle a is selected such that the nozzles 13a-e are inclined toward the third cutting head 8c. The angle a can, for example, be between 10° and 50°.

[0065] To crush the product, more or fewer than three cutting sets 7a, 7b, 7c can be arranged in the housing 3. It is understood that in this case, the housing 3 should be dimensioned larger or smaller in the axial direction than is the case in Fig. 1.

[0066] It is also possible to design the cutting device 4 differently than the cutting device 4 shown in Fig. 1, Fig. 2 and Fig. 3, which exclusively comprises cutting sets 7a-c, in which a stationary perforated plate 9a, 9b, 9c interacts with a respective rotating cutting head 8a, 8b, 8c to produce a scissor cut. For example, the cutting device 4 can have one or more cutting sets in which a stationary perforated plate interacts with a rotating perforated plate to shred the product, as described in EP 2 987 557 B1. With such a cutting set, the product is crushed and squashed rather than cut and therefore appears creamier than is the case with comminution using a cutting set in which a cutting head interacts with a stationary perforated plate, or with a cutting set that has a centrifugal cutting ring (rotor-stator principle).Ideally, the different cutting sets are dimensioned so that they fit into one and the same (cutting set) housing 3.

[0067] It is understood that a fluid in the form of a liquefied gas does not necessarily have to be supplied to the respective intermediate space 11a, 11b to cool the product. Instead of a liquefied gas, a gas can also be supplied to a respective intermediate space 11a, 11b, which can serve, for example, to inertize the product or to assist the conveying action of the cutting device 4 if the product tends to stick together or clump, or a liquid can be supplied to add a dye or the like to the product, or steam can be supplied to heat the product. In principle, it is possible for the gaseous fluid to remain in the comminuted product. However, it is also possible to separate the comminuted product from the gaseous fluid after it exits the comminution machine 1.For example, for this purpose, the comminuted product and the gaseous fluid can be fed to a collecting container for demixing, from which the gaseous fluid is sucked off.

Claims

A comminution machine (1) for comminution of a product, comprising: a cutting device (4) for comminution of the product, which cutting device has at least two cutting sets (7a-c), a drive shaft (5) for driving the cutting sets (7a-c), and a housing (3) in which the cutting sets (7a-c) are arranged one behind the other along a longitudinal axis (L) of the drive shaft (5), characterized in that the comminution machine (1) is designed to supply a fluid in the form of a liquefied gas into at least one intermediate space (11a, 11b) which is formed in the housing (3) between two cutting sets (7a, 7b; 7c, 7d) which are adjacent along the longitudinal axis (L) of the drive shaft (5). Crushing machine according to claim 1, which has at least one nozzle (13a-e) for the outlet of the fluid into the intermediate space (11a, 11b), which nozzle is formed at one end of a feed channel (12a-e) which preferably runs in the housing (3).Comminution machine according to claim 2, wherein the nozzle (13a-e) is designed for the fluid to exit substantially tangentially with respect to the longitudinal axis (L) of the drive shaft (5). Comminution machine according to claim 2 or 3, wherein the nozzle (13a-e) is designed for the fluid to exit in the direction of rotation (D) of the drive shaft (5). Comminution machine according to one of claims 2 to 4, wherein the nozzle (13a-e) is formed in a projection (14a-e) of the housing (3) which projects into the intermediate space (11a, 11b), wherein the projection (14a-e) preferably tapers radially in the direction of the longitudinal axis (L) of the drive shaft (5). Comminution machine according to claim 5, wherein the nozzle (13a-e) is formed on a side (15a-e) of the projection (14a-e) facing away from the direction of rotation (D) of the drive shaft (5). Comminution machine according to one of claims 2 to 6, wherein the nozzle (13a-e) is arranged at a radial distance (R) from the longitudinal axis (L) of the drive shaft (5) that is less than 80%, preferably less than 60%, particularly preferably less than 40% of a maximum radius (RM) of the intermediate space (11a, 11b) in the housing (3). Comminution machine according to one of claims 2 to 7, wherein the nozzle (13a-e) is oriented at an angle (α) with respect to a plane (YZ) perpendicular to the longitudinal axis (L) of the drive shaft (5). Crushing machine according to one of the preceding claims, further comprising: at least one controllable valve (16) for the controlled supply of the fluid into the intermediate space (11a, 11b).A comminution machine according to one of the preceding claims, wherein at least one cutting set (7a-c) has a stationary perforated plate (9a-c) that cooperates with a rotating cutting head (8a-c) to comminute the product. A comminution machine according to claim 10, wherein an axial distance (A) between the cutting head (8a-c) and the stationary perforated plate (9a-c) is adjustable. A method for comminution of a product using a comminution machine (1), in particular a comminution machine (1) according to one of the preceding claims, comprising: Comminution of the product in a cutting device (4) of the comminution machine (1), wherein the cutting device (4) has at least two cutting sets (7a-c) which are arranged along a longitudinal axis (L) of a Drive shaft (5) are arranged one behind the other in a housing (3) and are driven by the drive shaft (5), characterized in that when the product is being shredded, a fluid in the form of a liquefied gas is supplied to at least one intermediate space (11a, 11b) in the housing (3), which is formed between two cutting sets (7a, 7b; 7b, 7c) adjacent along the longitudinal axis (L) of the drive shaft (5). Method according to claim 12, in which a liquefied gas in the form of CO2 or N2 is supplied to the intermediate space for cooling the product. Method according to claim 12 or 13, in which the fluid is supplied to the intermediate space (11a, 11b) only in the event that the presence of the product in the cutting device (4) is detected.Method according to one of claims 12 to 14, in which at least a portion of the fluid supplied to the intermediate space (11a) is separated from the product in at least one intermediate space (11b) of the cutting device (4) located downstream in the product conveying direction and / or after exiting the comminution machine (1). Method according to one of claims 12 to 15, in which a temperature of the comminuted product after exiting the cutting device (4) is controlled by adjusting a supply quantity of the fluid supplied to the at least one intermediate space (11a, 11 b) is regulated. Method according to one of claims 12 to 16, wherein the liquefied gas supplied to the at least one intermediate space (11a, 11b) is provided subcooled relative to its phase equilibrium pressure to avoid gas bubbles.

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