Tunnel type radio frequency thawing device and application thereof

Abstract

The application discloses a tunnel type radio frequency thawing device and application thereof, and solves the problem of rapid thawing of meat products or pre-prepared dishes. The device comprises a radio frequency thawing unit module and a tunnel type logistics conveying system module. The tunnel type logistics conveying system module comprises a conveying chain plate, a speed regulating motor and a chain transmission mechanism. The speed regulating motor is connected to and drives the conveying chain plate to rotate through the chain transmission mechanism. An incoming goods guiding cavity, a thawing cavity and an outgoing goods guiding cavity are sequentially arranged above the conveying chain plate. The radio frequency thawing unit module and the tunnel type logistics conveying system module realize rapid thawing of meat when the meat passes through through the PLC control system. In the application, the upper plate (or / and the lower plate) is designed to be height-adjustable. A servo electric cylinder is used to make the distance between the upper surface of the frozen object and the lower plane of the upper plate more accurate. The thickness of the frozen object is fed back in a closed loop, the power of the radio frequency generator is adjusted, and the closed loop feedback linkage control is established.

Description

Technical Field

[0001] This invention relates to the field of devices and technologies for maintaining the quality of thawing meat products and prepared dishes, and in particular to a radio frequency thawing device and its usage method. This device can achieve coordinated operation of multiple functional devices through a control system, creating suitable radio frequency power, radio frequency electrode spacing and optimal thawing rate, thereby improving the quality maintenance of meat products and prepared dishes during the thawing process, reducing moisture loss during thawing and preventing excessive microbial levels. Background Technology

[0002] Some fresh meat products and prepared dishes can only retain their nutritional value by being stored at low temperatures. However, they must be thawed before consumption. Currently, the main thawing methods include air thawing, water bath thawing, microwave thawing, and radio frequency thawing. Of course, each thawing method has its own unique advantages and disadvantages. For example, air thawing has the advantage of zero energy consumption, but its disadvantages include greater moisture loss and a poorer taste.

[0003] The principle of radio frequency (RF) thawing is to place the product to be thawed between two parallel electrodes that alternately radiate radio waves. Overall, RF thawing has superior thawing capabilities and post-thawing quality retention compared to other methods. However, current research on RF thawing technology mainly focuses on power and RF frequency under conditions of fixed electrode spacing, which somewhat limits the application scenarios of the equipment. During application, because different frozen items have different enthalpies, their temperatures during the latent heat to sensible heat conversion also differ, resulting in significant differences in the required heat, prolonged thawing time, and even cell water leakage, leading to nutrient loss.

[0004] Furthermore, radio frequency (RF) defrosting has strict requirements on the geometry of the material being heated, generally requiring a relatively regular shape (currently, cuboids and cylinders are commonly used). If the material is irregularly shaped, the thinner corners are more easily penetrated by RF waves, leading to rapid heat generation and overheating, resulting in a "corner concentration effect." Additionally, since the loss factor of frozen materials increases with temperature in the RF band, higher-temperature areas have a larger loss factor. During heating, these areas absorb more RF energy, causing heat concentration and localized overheating—a phenomenon known as "thermal offset." Both corner concentration and thermal offset contribute to the non-uniformity of RF defrosting, especially when the initial temperature or electromagnetic field distribution is uneven, further exacerbating the temperature non-uniformity after heating. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a structural composition and application method of a rapid thawing device for meat products and prepared dishes, based on traditional methods for thawing meat products and prepared dishes. The technical problem to be solved is how to create a rapid thawing radio frequency energy source and an optimal electrode spacing to meet the technical and device requirements for rapid thawing of meat products or prepared dishes.

[0006] The purpose of this invention is to provide a device capable of rapid defrosting.

[0007] Another objective of this invention is to provide the structure and composition of a rapid defrosting device; it also provides a method for using the rapid defrosting device.

[0008] The technical solution adopted by this invention to solve its technical problem is as follows:

[0009] A tunnel-type radio frequency (RF) defrosting device, which can also be understood as an equipment model or apparatus, includes an RF defrosting unit module and a tunnel-type logistics conveying system module. The RF defrosting unit module and the tunnel-type logistics conveying system module, through a PLC control system, enable rapid defrosting of meat as it passes through. That is, the defrosting process is completed as the item to be defrosted passes through the tunnel-type logistics conveying system. This process involves collecting information such as the temperature, thickness, and outline of the frozen item. This collected information is digitized and fed back to the control system, which adjusts the distance between the electrode plates and the frozen item, and regulates the conveying speed of the conveying system to achieve precise control.

[0010] Its features are,

[0011] The tunnel-type logistics conveying system module includes a conveyor chain plate, a speed-regulating motor, and a chain drive mechanism. The speed-regulating motor is connected to and drives the conveyor chain plate to rotate through the chain drive mechanism. An infeed guide cavity, a thawing cavity, and an outfeed guide cavity are arranged in sequence above the conveyor chain plate.

[0012] The inlet guide cavity is equipped with a correction mechanism and / or a camera;

[0013] An infrared thickness gauge is installed on the outside of the inlet guide cavity. The probe of the infrared thickness gauge measures the thickness of the frozen material and obtains thickness data.

[0014] The defrosting chamber is equipped with at least one radio frequency defrosting unit module, and the walls of the defrosting chamber are lined with microwave shielding material. Each radio frequency unit module consists of a radio frequency generator, an upper electrode plate, a lower electrode plate, a wind-cooled heat sink, and a spacing adjustment mechanism. The upper and lower electrode plates are respectively connected to the electrodes of the radio frequency generator. The upper electrode plate is installed above the bearing surface of the conveyor chain plate, and the lower electrode plate is installed below the bearing surface of the conveyor chain plate, through the spacing adjustment mechanism. The distance between the upper and lower electrode plates is adjusted within the range of 25cm to 45cm according to the following rules:

[0015] When the thickness of the frozen material is greater than 8.5 cm, the upper electrode plate moves by a distance equal to the difference between the measured thickness and the previous measured thickness. When the difference is positive, it moves upwards; when the difference is negative, it moves downwards. During the movement of the upper electrode plate, the real-time power of the corresponding RF generator is automatically adjusted according to the following rules:

[0016] y = kx + b

[0017] Real-time power of RF generator (in kW)

[0018] x Distance between upper and lower plates (in cm)

[0019] k is the proportionality coefficient.

[0020] b is a constant

[0021] The air-cooled heat sink is used to cool the radio frequency generator.

[0022] An infrared thermometer is installed in the thawing chamber. The probe of the infrared thermometer measures the temperature of the thawing object and obtains the temperature value. If the detected temperature value is lower than the set value (e.g., -1 degree), the speed of the conveyor chain is reduced by the control system. If the detected temperature value is higher than the set value, the speed of the conveyor chain is increased by the control system.

[0023] The lower electrode plate is installed below the chain bearing surface via another set of spacing adjustment mechanisms.

[0024] The spacing adjustment mechanism includes a servo electric cylinder and a linear slide rail. The servo electric cylinder is fixed to the top of the defrosting chamber and is vertically arranged. The other end of the servo electric cylinder is mechanically connected to the upper electrode plate. At the same time, two sets of linear slide rails are arranged between the upper electrode plate and the defrosting chamber, and the linear slide rails are vertically arranged.

[0025] The radio frequency (RF) defrosting unit module consists of two modules, arranged one after the other along the defrosting path. Its main function is to provide stepped RF energy to the frozen items entering the defrosting chamber. This stepped RF energy allows for flexible adjustment of frozen items of different types and thicknesses, enabling rapid defrosting.

[0026] A camera is installed directly above the inlet guide cavity. The camera identifies the type and outline of the frozen item. By combining the correction mechanism with the camera's visual recognition, the frozen item is centered. The advantage of centered positioning is that it places the frozen item in the optimal radiation range, improving the accuracy of defrosting.

[0027] The correction mechanism is as follows: a servo electric cylinder is set on one side of the forward path of the conveyor chain plate. One end of the servo electric cylinder is fixed to the equipment, and a baffle is installed on the other end. The position of the baffle is controlled by the servo electric cylinder.

[0028] Each upper electrode and each lower electrode are composed of 3N small electrodes, where N is a natural number greater than or equal to 1. Each small electrode is individually connected to the radio frequency generator and is equipped with an electromagnetic switch, which individually controls the opening and closing of each small electrode.

[0029] Each small electrode is installed individually via a spacing adjustment mechanism.

[0030] The control system is a PLC control system, which is integrated with and electrically connected to the servo electric cylinder, radio frequency generator, speed-regulating motor, and various probes, sensors, infrared thermometers, infrared thickness gauges, and cameras.

[0031] The radio frequency generator is a low-voltage 48V solid-state semiconductor transistor generator with a frequency of 13.56MHz, adjustable power, and a sine wave for the radio frequency wave.

[0032] The application of a tunnel-type radio frequency defrosting device in pork defrosting follows these steps:

[0033] Step 1: Select frozen goods that meet the requirements; the thickness of the frozen goods packaging should not exceed 28cm.

[0034] Step 2: Initial setting: The distance between the upper surface of the frozen object and the upper electrode plate is approximately 7.5cm ± 0.1cm, and the distance between the upper and lower electrodes is 25cm. The radio frequency generator, air-cooled heat sink, speed-regulating motor, infrared thermometer, infrared thickness gauge, and camera are turned on simultaneously.

[0035] Step 3: Place the frozen item on the conveyor belt. Based on the thickness data measured by the infrared thickness gauge, automatically adjust the position of the upper electrode plate and the real-time power of the RF generator. When the thickness of the frozen item is greater than 8.5cm, the upper electrode plate moves. The moving distance is the difference between the measured thickness data and the previously measured thickness data. When the difference is positive, it moves upward; when the difference is negative, it moves downward. During the movement of the upper electrode plate, the real-time power of the corresponding RF generator is automatically adjusted according to the following rules:

[0036] y = kx + b

[0037] Y-frequency generator real-time power, unit kW

[0038] x Distance between upper and lower plates, in cm

[0039] k is the proportionality coefficient.

[0040] b is a constant

[0041] Step 4: Adjust the conveyor speed of the conveyor chain based on the temperature value measured by the infrared thermometer. If the detected temperature value is lower than the set value, reduce the speed of the conveyor chain through the control system; if the detected temperature value is higher than the set value, increase the speed of the conveyor chain through the control system.

[0042] Step 5: Repeat the steps in Step 4 until the best thawing efficiency is achieved, and weigh the frozen food after thawing to calculate the weight loss rate of the frozen food.

[0043] Step Six: After the batch of frozen goods has finished thawing, turn off the radio frequency generator and the conveyor belt, delay the shutdown of the air-cooled radiator, and finally disconnect the main power supply.

[0044] The application of a tunnel-type radio frequency defrosting device in pork defrosting follows these steps:

[0045] Step 1: Select frozen goods that meet the requirements; the thickness of the frozen goods packaging should not exceed 28cm.

[0046] Step 2: Initial setting: The distance between the upper surface of the frozen object and the upper electrode plate is approximately 7.5cm ± 0.1cm, and the distance between the upper and lower electrodes is 25cm. The radio frequency generator, air-cooled heat sink, speed-regulating motor, infrared thermometer, infrared thickness gauge, and camera are turned on simultaneously.

[0047] Step 3: Place the frozen item on the conveyor belt. Based on the visual recognition image provided by the camera, obtain the outer contour image of the frozen item. Control the opening of the small electrode plate directly above the frozen item according to the outer contour image. At the same time, all or part of the small electrode plates in the area not covered by the frozen item are closed.

[0048] Step 4: Adjust the conveyor speed of the conveyor chain based on the temperature value measured by the infrared thermometer. If the temperature value is lower than the set value, reduce the speed of the conveyor chain through the control system; if the temperature value is higher than the set value, increase the speed of the conveyor chain through the control system.

[0049] Step 5: Repeat the steps in Step 4 until the best thawing efficiency is achieved, and weigh the frozen food after thawing to calculate the weight loss rate of the frozen food.

[0050] Step Six: After the batch of frozen goods has finished thawing, turn off the radio frequency generator and the conveyor belt, delay the shutdown of the air-cooled radiator, and finally disconnect the main power supply.

[0051] In step three, each small electrode plate is adjusted by a spacing adjustment mechanism, and the spacing between the small electrodes and the real-time power of the radio frequency generator are automatically adjusted according to the thickness data measured by the infrared thickness gauge.

[0052] The beneficial effects of this invention are:

[0053] This invention improves upon the fixed structure of the upper and lower electrode plates, making the upper (and / or lower) electrode plates height-adjustable. The use of a servo electric cylinder allows for more precise positioning of the distance between the upper surface of the frozen material and the lower plane of the upper electrode plate. Closed-loop feedback of the frozen material thickness controls the power adjustment of the radio frequency generator, establishing a closed-loop feedback linkage control. Simultaneously, the operating speed of the conveyor chain is adjusted in real time based on the temperature measurement results from the infrared thermometer at the outlet of the defrosting chamber to achieve maximum defrosting capacity. This technology, by adjusting the conveyor speed and the distance between the frozen material and the electrode plates, can significantly reduce the water loss rate and temperature unevenness of the frozen material during defrosting, which is of positive significance for improving defrosting efficiency and quality. Attached Figure Description

[0054] Figure 1 This is a horizontal view of the present invention.

[0055] Figure 2 This is a longitudinal view of the present invention.

[0056] Figure 3 This is a plan view of a tunnel-type logistics conveyor system module.

[0057] Figure 4 This is a schematic diagram of the structural principle of the present invention.

[0058] Figure 5 This is the combination of electrode plates in Example 2.

[0059] Figure 6 This is the combination of electrode plates in Example 3.

[0060] In the picture:

[0061] 00 Frozen food,

[0062] 01 Inlet guide cavity, 02 Thawing cavity, 03 Outlet guide cavity

[0063] 10. Conveyor chain plates, 11. Speed-regulating motors

[0064] 21. Camera; 22. Infrared thickness gauge; 23. Infrared thermometer.

[0065] 31 RF generator, 32 upper electrode plate, 33 lower electrode plate, 34 air-cooled heat sink, 35 pitch adjustment mechanism. Detailed Implementation

[0066] A tunnel-type radio frequency (RF) defrosting device includes an RF defrosting unit module and a tunnel-type logistics conveying system module. The RF defrosting unit module and the tunnel-type logistics conveying system module, through a central control system, enable rapid defrosting of meat as it passes through. That is, the defrosting process is completed as the item to be defrosted passes through the tunnel-type logistics conveying system. This process involves collecting information such as the temperature, thickness, and outline of the frozen item. This collected information is digitized and fed back to the control system, which adjusts the distance between the electrode plates and the frozen item, and regulates the rotation speed of the conveying system to achieve precise control.

[0067] Example 1

[0068] This embodiment is a specific and detailed implementable process, and is an exemplary expression of the invention. This expression process is intended to help and guide relevant personnel to reproduce and reproduce the technology, and does not constitute a strict self-limitation of the invention.

[0069] refer to Figures 1 to 4 One of the two main modules, the tunnel-type logistics conveying system module, constructs a tunnel-like passageway (also known as a tunnel) for frozen goods. Within this passageway (tunnel), a radio frequency (RF) defrosting environment is created. This environment is semi-enclosed, allowing meat products or prepared dishes to be transported within the RF environment. As the meat products or prepared dishes pass through this RF environment at a constant speed, they are rapidly defrosted by the RF effect. Specifically, in the aforementioned tunnel-type logistics conveying system module, a conveyor chain plate 10 serves as the carrier for placing frozen goods, such as meat products or prepared dishes. Frozen goods 00 are placed on the conveyor chain plate, which is part of the chain drive mechanism and is speed-controlled by a variable-speed motor 11. Driven by the variable-speed motor 11, the conveyor chain plate and the frozen goods it carries sequentially enter the inlet guide cavity 01, the defrosting cavity 02, and the outlet guide cavity 03 via the chain drive mechanism.

[0070] The operating speed of the aforementioned conveyor chain plate is controlled by the speed-regulating motor 11, which operates at a constant speed or variable speed according to the program and instructions set by the PLC.

[0071] It should be noted that 00 in the diagram represents frozen food, which includes, but is not limited to, frozen meat and pre-cooked dishes.

[0072] Furthermore, the materials used to compose or constitute the aforementioned inlet guide cavity, thawing cavity, and outlet guide cavity are all food-grade stainless steel, such as 304 stainless steel, meeting food application requirements. Additionally, the thawing cavity has a shielded inspection door on the side for easy replacement or maintenance of components such as the RF generator and electrode plates (including the upper and lower electrode plates). Both the inlet and outlet guide cavities are equipped with flexible silicone curtains, creating a semi-enclosed thawing environment both inside and outside. The flexible silicone curtains maintain a slight gap with the conveyor chain plate and must not interfere with the smooth passage of frozen goods.

[0073] Furthermore, the conveyor chain plate 10 is a plastic-steel mesh belt module made of polypropylene material. The material must be adaptable to high and low temperatures, allowing for arbitrary splicing. The openings are uniformly distributed in strip or trapezoidal shapes. The module shaft spacing should preferably be set between 60mm and 80mm, and the opening ratio should be greater than 50%. The openings should be regular and easy to clean. The connecting shaft of the conveyor chain plate is made of polypropylene material. The tension of the conveyor chain plate is achieved by adjusting the position of the tensioning wheel connected to it. The driving device for the conveyor chain plate is a speed-regulating motor with a reducer, and its speed can be steplessly adjusted. The aforementioned conveyor chain plate can circulate under the drive of the sprocket, forming a circulating conveyor belt structure.

[0074] The so-called inlet guide cavity refers to a centrally located section in the conveyor path used to guide meat products.

[0075] Furthermore, a correction mechanism is installed within the inlet guide cavity to correct the frozen items. For example, a common correction mechanism employs visual recognition technology. A camera 21 is positioned directly above the inlet guide cavity. The camera identifies the type (meat or non-meat) and outline (divided into regions based on size) of the frozen item. By combining the correction mechanism with the camera's visual recognition, the frozen item is centered. The advantage of this centered positioning is that it places the frozen item within the optimal radiation range, improving the accuracy of defrosting.

[0076] A feasible correction mechanism involves installing a servo cylinder on one side of the conveyor chain's forward path. One end of the servo cylinder is fixed to the equipment, and the other end is fitted with a baffle. The position of the baffle is controlled by the servo cylinder, and the position of the baffle corrects the deviation of the frozen goods. That is, if the frozen goods deviate to one side, their position is corrected under the constraint of the baffle.

[0077] Alternatively, the correction mechanism can be designed with two correction vanes, each mounted on one side. When the frozen item passes the position of a correction vane, the elastic force of the two vanes automatically corrects the item's direction. The elastic force of the two correction vanes should be equal and they should be symmetrically arranged.

[0078] The aforementioned correction mechanism and camera-based visual recognition technology are optional features, which ensure that the frozen items entering the defrosting chamber are in the optimal position.

[0079] The infrared thickness gauge 22 is installed outside the inlet guide cavity or near the soft curtain. After measuring the batch of frozen items, the infrared thickness gauge obtains the thickness data and is used to guide and adjust the position of the upper electrode plate to the optimal value, that is, to adjust the distance between the upper electrode plate and the frozen items. Theoretically, through configuration, this embodiment can meet the measurement and thawing needs of frozen items with a maximum thickness not exceeding 28cm.

[0080] The frozen contents entering the defrosting chamber are centered.

[0081] The defrosting chamber 02 is mainly equipped with one or more radio frequency (RF) defrosting unit modules. For example, two RF defrosting unit modules are set one after the other along the defrosting path. Their main function is to provide stepped RF energy to the frozen items entering the defrosting chamber. The stepped RF energy can be flexibly adjusted for frozen items of different types and thicknesses, achieving rapid defrosting.

[0082] Furthermore, the two radio frequency defrosting unit modules can be controlled independently. For example, the distance between the electrode plates and the frozen object in the two radio frequency defrosting unit modules can be controlled and adjusted respectively.

[0083] Specifically, a complete radio frequency (RF) defrosting unit module consists of an RF generator 31, an upper electrode plate 32, a lower electrode plate 33, a fan-cooled heat sink 34, and a spacing adjustment mechanism 35. The upper and lower electrode plates are connected to the electrodes of the RF generator, and both plates are functional components for RF emission. The fan-cooled heat sink is used to cool the RF generator, solving the heat dissipation problem of electronic components.

[0084] In this embodiment, the distance between the upper electrode plate 32 and the frozen object is adjustable. Similarly, the actual distance between the lower electrode plate 33 and the frozen object is also adjustable. This requires a distance adjustment mechanism to be provided at either the upper or lower electrode plate. In other words, the distance adjustment mechanism enables free adjustment of the two electrode plates. In this embodiment, the adjustment is performed using a micro-motor at a slow speed, which is millimeter-level adjustment. That is, the distance adjustment mechanism allows for millimeter-level adjustment of the upper electrode plate and / or the lower electrode plate respectively.

[0085] On the conveyor chain plate 10, the conveyor chain plate engages with the aforementioned sprockets via chains on both sides. One set of sprockets is connected to a speed-regulating motor, and the connection method is chain drive. Therefore, the conveyor chain plate located on the cargo surface serves as the bearing surface for frozen goods, and this bearing surface is the reference surface for adjusting the upper and lower electrode plates. For example, this bearing surface is 8cm-12cm away from the lower electrode plate.

[0086] The upper and lower electrode plates need to be installed inside the thawing chamber 02, and are connected to the external environment through the inlet guide chamber and the outlet guide chamber. The upper and lower electrode plates should be installed in parallel. In this embodiment, the height of the lower electrode plate is fixed (or adjustable), and the height of the upper electrode plate can be adjusted. The minimum distance between the upper and lower electrode plates is 25cm, and the maximum distance is 45cm. Generally, the frozen item is located in the center of the upper and lower electrode plates.

[0087] The so-called spacing adjustment mechanism 35 includes a servo cylinder and linear guide rails. The servo cylinder is fixed to the top of the defrosting chamber and is vertically positioned. This servo cylinder employs closed-loop servo control with a control accuracy of 0.1mm, providing power for the movement of the upper electrode plate. The other end of the servo cylinder is mechanically connected to the upper electrode plate. Simultaneously, two sets of vertically positioned linear guide rails are installed between the upper electrode plate and the defrosting chamber. These linear guide rails, along with the servo cylinder, adjust the height of the upper electrode plate. The movement of the upper electrode plate follows the linear guide rails, powered by the servo cylinder. The displacement distance is related to the thickness of the frozen object. Specifically, the thickness data fed back by an infrared thickness gauge ensures that the distance between the upper surface of the frozen object and the lower plane of the upper electrode plate is controlled within a reasonable spacing of ±0.1cm, forming a closed-loop control program.

[0088] Similarly, the aforementioned adjustable structure can be established between the lower electrode plate and the defrosting chamber, so that the distance between the bottom of the frozen object and the upper surface of the lower electrode plate can be controlled within a reasonable range of ±0.1cm.

[0089] Furthermore, the servo electric cylinder has a stroke of 0-30cm along the linear slide rail, is under closed-loop servo control, and has a control accuracy of 0.1mm. Its adjustment speed is set to 10mm / second. The vertical displacement of the servo electric cylinder is provided with key position stroke limit points to ensure that the displacement is within the control range and that the distance between the upper and lower electrode plates is greater than the minimum safe distance. In this embodiment, the minimum safe distance is set to 25cm.

[0090] In the implementation of this technology, the RF generator adopts variable power control technology. For example, the power output of a certain model of RF generator is 1 to 7 kW. That is, the maximum output power of the RF generator is 7 kW and the minimum output power is 1 kW. During normal operation, the real-time power of the RF generator is automatically adjusted between 1 and 7 kW to ensure normal operation.

[0091] Furthermore, the real-time power of the RF generator is adjusted proportionally to the displacement of the servo cylinder; that is, the greater the distance between the upper and lower electrode plates, the greater the real-time power of the RF generator. For example, the output power of a certain model of RF generator is 1-7kW. When the servo cylinder drives the upper electrode plate to the top of the displacement, i.e., the distance between the upper and lower electrode plates is 45cm, the real-time power of the RF generator is at its maximum. When the servo cylinder drives the upper electrode plate to the bottom of the displacement, i.e., the distance between the upper and lower electrode plates is 25cm, the real-time power of the RF generator is at its minimum. The real-time power of the RF generator in the intermediate region is calculated according to the following formula:

[0092] y = kx + b

[0093] Real-time power of RF generator (in kW)

[0094] x Distance between upper and lower plates (in cm)

[0095] k proportionality coefficient

[0096] b constant

[0097] For example: the maximum output power of the RF generator is 7kW, and the minimum output power is 1kW. The formula can be calculated as follows:

[0098] y = 0.3x - 6.5

[0099] In this technique, the derivation formulas for the proportionality coefficient k and the constant b are as follows:

[0100] Y1=45k+b

[0101] Y2=25k+b

[0102] Y1 RF Generator Maximum Output Power (kW)

[0103] Y2 RF Generator Minimum Output Power (kW)

[0104] k proportionality coefficient

[0105] b constant

[0106] For example, assuming the minimum output power of the RF generator is 3kW and the maximum output power is 8kW, then when the upper and lower plates are at their minimum distance of 25cm, the power of the RF generator is 3kW, and when the upper and lower plates are at their maximum distance of 45cm, the power of the RF generator is the maximum of 8kW.

[0107] Substitute into the formula respectively

[0108] 8 = 45k + b

[0109] 3 = 25k + b

[0110] The calculated value of k is 0.25, and the value of b is -3.25.

[0111] Thus, the values ​​of k and b can be calculated.

[0112] That is, the k and b values ​​are determined based on the maximum and minimum output power of the RF generator, and then the real-time power of the RF generator at any position in the middle region between the upper and lower plates can be derived based on the k and b values.

[0113] Furthermore, the infrared thermometer 23 is installed on the upper part of the upper electrode plate, and the temperature measuring point of the infrared thermometer is selected at the outlet end of the defrosting chamber. The measurement accuracy of the infrared thermometer is at the 0.1 degree level. The conveying speed of the conveyor chain is adjusted according to the temperature measured by the infrared thermometer, which is a closed-loop control design to achieve the optimal defrosting capacity of the equipment and prevent over-defrosting or under-defrosting.

[0114] Furthermore, the thawing chamber is a cuboid structure, and it is equipped with microwave shielding function by attaching or coating shielding material on the inner or outer wall of the thawing chamber to prevent microwave leakage.

[0115] Furthermore, the radio frequency generator is preferably a solid-state semiconductor transistor generator, which is installed on the upper part of the device's defrosting chamber.

[0116] Furthermore, the radio frequency generator has a low voltage of 48V, a frequency of 13.56MHz, adjustable power, and uses a sine wave for the radio frequency wave.

[0117] Furthermore, the radio frequency generator is cooled by air cooling, and the speed of the air cooling fan is adjusted by frequency conversion based on the temperature of the radio frequency generator's working environment to ensure that the radio frequency generator is in a good working environment.

[0118] As a technical alternative, the upper electrode plate position adjustment can be achieved automatically using the thickness gauge or manually. Manual adjustment involves setting parameters on the control panel and pressing the adjustment button until the set distance is reached. When using automatic adjustment, the zero point is set when the upper electrode plate is at its lowest position (i.e., the distance between the upper and lower electrodes is 25cm), and the infrared thickness gauge reading is less than or equal to 8.5cm. When the infrared thickness gauge reading is greater than 8.5cm, the upper electrode plate begins to move. The moving distance is the difference between the measured value and the previous measured value; a positive value moves it upwards, and a negative value moves it downwards, until it reaches the limit point.

[0119] Furthermore, the control system refers to the control center that realizes the coordinated action of the system, that is, the brain of the entire device. In this embodiment, it is a PLC control system. This control system is integrated and electrically connected with the servo cylinder, radio frequency generator, speed-regulating motor and various probes, sensors, infrared thermometers, infrared thickness gauges and cameras. It is used to realize the speed setting of the servo cylinder, the setting of the electrode plate stroke limit point, the setting of the corresponding parameters of the servo cylinder displacement and the power of the radio frequency generator, and the stepless speed regulation of the speed controller. Through the intelligent and precise control of the control system and the continuous improvement of the big data, it can achieve precise control of different meat textures, thicknesses and temperatures, and control the water loss rate during the thawing process to be less than 0.5%.

[0120] The basic steps of applying the above-mentioned tunnel-type radio frequency defrosting device to pork defrosting are as follows:

[0121] Step 1: Select the required frozen items. For example, when selecting items, first choose low-temperature pork of the same type and in the same package. The thickness of the package should not exceed 28cm, and the width of the package should be less than the maximum allowable range of the equipment. Weigh the frozen items.

[0122] Step Two: Based on the pork's temperature and packaging dimensions, after measurement by an infrared thickness gauge installed in the infeed guide cavity, adjust the linear stroke of the servo cylinder to ensure the distance between the upper surface of the frozen item and the lower plane of the upper electrode plate is approximately 7.5cm, the optimal working distance. Adjust the RF generator to its maximum power within a suitable range. The RF generator utilizes low-voltage solid-state semiconductor technology, operates at 48V, and features an air-cooled structure. The RF generator, air-cooled heat sink, speed-regulating motor, infrared thermometer, infrared thickness gauge, and camera are simultaneously activated.

[0123] Step 3: Place the pork on the conveyor belt and feed the frozen pork into the defrosting chamber at a uniform speed. At the same time, turn on the RF generator switch to put it into working condition. The fan that cools the RF generator is also turned on to cool it down.

[0124] When automatic adjustment is used, the zero point is set when the upper electrode plate is at its lowest position (i.e., the distance between the upper and lower electrode plates is 25cm), and the infrared thickness gauge reading is less than or equal to 8.5cm. When the infrared thickness gauge reading is greater than 8.5cm, the upper electrode plate begins to move. The moving distance is the difference between the measured value and the previous measured value; a positive value moves it upwards, and a negative value moves it downwards, until it reaches the travel limit point. The distance between the electrode plates and the frozen pork is dynamically adapted and adjusted, and this adjustment process is completed automatically.

[0125] Furthermore, the lower electrode plate moves in conjunction with the upper electrode plate and moves in the direction of demand.

[0126] During the adjustment of the gap between the upper and lower electrodes, the real-time power of the RF generator is adjusted according to the following formula:

[0127] y = kx + b

[0128] Real-time power of RF generator (in kW)

[0129] x Distance between upper and lower plates (in cm)

[0130] k proportionality coefficient

[0131] b constant

[0132] Step 4: Based on the temperature value measured by the infrared thermometer located at the outlet of the thawing chamber, further adjust the conveyor speed of the conveyor chain. For example, if the temperature at the outlet of the thawing chamber is set to -1 degree Celsius, when the temperature measured by the infrared thermometer is below -1 degree Celsius, the temperature signal is transmitted to the PLC. Based on calculations, the conveyor speed is reduced to avoid insufficient thawing. When the temperature measured by the infrared thermometer is above -1 degree Celsius, the conveyor speed is increased based on calculations to avoid over-thawing.

[0133] Step 5: Repeat the steps in Step 4 until the best thawing efficiency is achieved, and weigh the frozen food after thawing to calculate the weight loss rate.

[0134] Step Six: After the equipment has thawed, first turn off the RF generator and the conveyor chain. After a certain delay to allow the RF generator to cool down, turn off the cooling fan, and then disconnect the main power supply to ensure equipment safety.

[0135] In this embodiment, the upper electrode plate (or / and lower electrode plate) employs a height-adjustable device, expanding the range of frozen object specifications. The use of a servo electric cylinder allows for more precise positioning of the distance between the upper surface of the frozen object and the lower plane of the upper electrode plate. Furthermore, the correlation between the frozen object thickness and the power of the RF generator is calculated, establishing a closed-loop feedback linkage control. The operating speed of the conveyor chain is adjusted in real-time based on the temperature measurement results from the infrared thermometer at the outlet of the defrosting chamber, achieving maximum defrosting capacity. This technology significantly reduces the water loss rate of frozen objects during defrosting. The RF generator utilizes low-voltage semiconductor transistor solid-state technology, avoiding damage to the magnetically controlled electron tube caused by unstable mains voltage. Semiconductor transistor solid-state technology has a lifespan of up to 10 years, significantly reducing operating costs. Additionally, the use of 48V low voltage greatly improves safety compared to high-voltage magnetically controlled electron tubes. The RF generator is cooled by air, avoiding significant water waste and electrical safety concerns.

[0136] Example 2

[0137] refer to Figure 5 This embodiment is a further improvement on Embodiment 1. In Embodiment 1, the upper and lower plates are designed as a single plate, while conventional frozen materials have irregular outlines, so it is necessary to further improve them.

[0138] The radio frequency defrosting unit module is improved by dividing the electrode plates (upper or lower plates) into blocks. For example, the upper plate is evenly divided into nine smaller plates. Figure 5 In sections A1 to A9, each small electrode plate is individually connected to the radio frequency generator and equipped with an electromagnetic switch. Each small electrode plate's operation is controlled independently via the electromagnetic switch. For example, when frozen meat is an irregular, approximately triangular shape, the two corners do not require much radio frequency energy, while the middle section requires more. Therefore, one or two of the three small electrode plates on the sides can be disconnected, while all three small electrode plates in the middle can be opened, achieving flexible thawing of the frozen meat.

[0139] The aforementioned small electrode plates, in conjunction with the aforementioned spacing adjustment mechanism, allow for further flexible control, which has a positive effect on improving the thawing effect, especially reducing the water loss rate during the thawing process.

[0140] The application of a tunnel-type radio frequency defrosting device in pork defrosting follows these steps:

[0141] Step 1: Select frozen goods that meet the requirements; the thickness of the frozen goods packaging should not exceed 28cm.

[0142] Step 2: Initial setting: The distance between the upper surface of the frozen object and the upper electrode plate is approximately 7.5cm ± 0.1cm, and the distance between the upper and lower electrodes is 25cm. The radio frequency generator, air-cooled heat sink, speed-regulating motor, infrared thermometer, infrared thickness gauge, and camera are turned on simultaneously.

[0143] Step 3: Place the frozen item on the conveyor belt. Based on the thickness data measured by the infrared thickness gauge, automatically adjust the position of the upper electrode plate and the real-time power of the radio frequency generator. When the thickness of the frozen item is greater than 8.5 cm, the upper electrode plate, composed of multiple small electrodes, moves. The moving distance is the difference between the measured thickness data and the previously measured thickness data. When the difference is positive, it moves upward; when the difference is negative, it moves downward. During the movement of the upper electrode plate, the real-time power of the corresponding radio frequency generator is automatically adjusted according to the following rules:

[0144] y = kx + b

[0145] Y-frequency generator real-time power, unit kW

[0146] x Distance between upper and lower plates, in cm

[0147] k proportionality coefficient

[0148] b constant

[0149] Simultaneously, based on the visual recognition image provided by the camera, the outer contour image of the frozen object is obtained. The opening of the corresponding small electrode plate directly above the frozen object is controlled according to this image. Meanwhile, all or partially closed small electrodes in areas not covered by the frozen object are closed; for example, the two small electrodes on the left are closed, leaving one electrode open. This embodiment achieves the function of precisely opening the small electrodes and accurately providing radiative defrosting energy for frozen objects with different contours (generally sheet-like), effectively solving the sharp-corner concentration effect in existing technologies and improving defrosting quality.

[0150] Step 4: Adjust the conveyor speed of the conveyor chain plate according to the temperature value measured by the infrared thermometer. For example, if the temperature at the outlet of the thawing chamber is set to -1 degree, if the measured temperature value is lower than -1 degree, the speed of the conveyor chain plate will be reduced through the control system; if the temperature value is higher than -1 degree, the speed of the conveyor chain plate will be increased through the control system.

[0151] Step 5: Repeat the steps in Step 4 until the best thawing efficiency is achieved, and weigh the frozen food after thawing to calculate the weight loss rate of the frozen food.

[0152] Step Six: After the batch of frozen goods has finished thawing, turn off the radio frequency generator and the conveyor belt, delay the shutdown of the air-cooled radiator, and finally disconnect the main power supply.

[0153] Example 3

[0154] refer to Figure 6 This embodiment is a further improvement on Embodiment 1. In Embodiment 1, the upper and lower plates are designed as a single plate, while conventional frozen materials have irregular outlines, so it is necessary to further improve them.

[0155] The radio frequency defrosting unit module is improved by dividing the electrode plates (upper or lower plates) into blocks. For example, the upper plate is evenly divided into three smaller plates: left, middle, and right. Figure 6 From B1 to B3, each electrode plate is installed in the defrosting chamber housing or frame via a set of spacing adjustment mechanisms. This means that the spacing between each small electrode plate and the frozen food can be individually controlled and adjusted. Each small electrode plate is individually connected to the radio frequency generator (RF generator), meaning that the spacing between each small electrode plate and the frozen food is individually controlled based on the size and shape of the frozen food. For example, when the frozen meat is an irregular, approximately triangular shape, the two corners do not require as much RF energy as the middle section. Therefore, the spacing between the small electrode plates on the sides and the frozen meat can be appropriately increased, while the spacing between the small electrode plates in the middle can be appropriately decreased, achieving regional RF energy delivery and enabling flexible defrosting of the frozen meat.

[0156] The difference between this embodiment and Embodiment 2 is that in step 3, the frozen food is placed on the conveyor chain. Based on the thickness data measured by the infrared thickness gauge, the position of the upper electrode and the real-time power of the radio frequency generator are automatically adjusted. When the thickness of the frozen food is greater than 8.5 cm, the multiple small electrodes are individually adjustable and controllable. That is, the radiation energy of each small electrode remains constant; what changes is the distance between each small electrode and the frozen food. By controlling the distance, the radiation energy received by the frozen food (e.g., frozen pork) is controlled, thereby controlling the thawing speed and quality. The instruction to adjust the distance of each small electrode comes from the visual recognition image provided by the camera. That is, the camera obtains an image of the outer contour of the frozen food and controls the movement distance of the corresponding small electrode directly above the frozen food based on the outer contour image. Simultaneously, the small electrodes in areas not covered by the frozen food are all closed, partially closed, or their distance is adjusted to the maximum. This embodiment achieves the function of precisely opening the small electrodes and precisely providing radiation thawing energy for frozen foods (generally sheet-like) with different contours, effectively solving the sharp corner concentration effect in the prior art and improving thawing quality.

[0157] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements to the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention.

Claims

1. A tunnel-type radio frequency defrosting device, comprising a radio frequency defrosting unit module and a tunnel-type logistics conveying system module, characterized in that, The tunnel-type logistics conveying system module includes a conveyor chain, a speed-regulating motor, and a chain drive mechanism. The speed-regulating motor is connected to and drives the conveyor chain to rotate through the chain drive mechanism. Above the conveyor chain, an inlet guide cavity, a thawing cavity, and an outlet guide cavity are arranged in sequence. The inlet and outlet guide cavities are equipped with flexible silicone curtains. Driven by the speed-regulating motor, the conveyor chain and the frozen items it carries are driven by the chain drive mechanism to enter the inlet guide cavity, the thawing cavity, and the outlet guide cavity in sequence. The open area ratio of the conveyor chain plate is greater than 50%; The inlet guide cavity is equipped with a correction mechanism and a camera. Through the combination of the correction mechanism and the camera's visual recognition, the frozen items are centered and positioned. An infrared thickness gauge is installed on the outside of the inlet guide cavity. The probe of the infrared thickness gauge measures the thickness of the frozen material and obtains thickness data. The defrosting chamber is equipped with two radio frequency (RF) defrosting unit modules, arranged one after the other along the defrosting path. The spacing between the electrode plates in each RF defrosting unit module and the frozen object is controllable and adjustable. Microwave shielding material is provided on the walls of the defrosting chamber. Each RF unit module consists of an RF generator, an upper electrode plate, a lower electrode plate, a fan-cooled heat sink, and a spacing adjustment mechanism. The upper and lower electrode plates are electrically connected to the RF generator. The upper electrode plate is mounted above the conveyor chain bearing surface via the spacing adjustment mechanism, while the lower electrode plate is mounted below the conveyor chain bearing surface via another spacing adjustment mechanism. Each upper and lower electrode plate consists of 3N smaller electrode plates, where N is a natural number greater than or equal to 1. Each smaller electrode plate is individually circuit-connected to the RF generator and equipped with an electromagnetic switch that individually controls the opening and closing of each smaller electrode plate. The spacing between the upper and lower electrode plates is adjustable within the range of 25cm to 45cm according to the following rules: When the thickness of the frozen material is greater than 8.5 cm, the upper electrode plate moves by a distance equal to the difference between the measured thickness and the previous measured thickness. When the difference is positive, it moves upwards; when the difference is negative, it moves downwards. During the movement of the upper electrode plate, the real-time power of the corresponding RF generator is automatically adjusted according to the following rules: y=kx+b y represents the real-time power of the RF generator, in kW. x is the distance between the upper and lower plates, in cm. k is the proportionality coefficient b is a constant The air-cooled heat sink cools the radio frequency generator; The spacing adjustment mechanism includes a servo electric cylinder and a linear slide rail. The servo electric cylinder is fixed to the top of the defrosting chamber and is vertically arranged. The other end of the servo electric cylinder is mechanically connected to the upper electrode plate. At the same time, two sets of linear slide rails are arranged between the upper electrode plate and the defrosting chamber, and the linear slide rails are vertically arranged. An infrared thermometer is installed in the thawing chamber. The probe of the infrared thermometer measures the temperature of the thawing object and obtains the temperature value. If the temperature value is lower than the set value, the speed of the conveyor chain is reduced by the control system; if the temperature value is higher than the set value, the speed of the conveyor chain is increased by the control system. The control system is a PLC control system, which is integrated and electrically connected with the servo cylinder, radio frequency generator, speed-regulating motor, and various probes, sensors, infrared thermometers, infrared thickness gauges, and cameras. It is used to realize the speed setting of the servo cylinder, the setting of the electrode plate stroke limit point, the setting of the corresponding parameters of the servo cylinder displacement and the power of the radio frequency generator, and the stepless speed regulation of the speed controller, so as to control the water loss rate during the thawing process to be less than 0.5%.

2. The tunnel-type radio frequency defrosting device according to claim 1, characterized in that, Each small electrode is installed individually via a spacing adjustment mechanism.

3. The application of tunnel-type radio frequency defrosting devices in defrosting, the steps are as follows: Step 1: Select frozen goods that meet the requirements; the thickness of the frozen goods packaging should not exceed 28cm. Step 2: Initial setting: The distance between the upper surface of the frozen object and the upper electrode plate is 7.5cm ± 0.1cm, and the distance between the upper and lower electrodes plate is 25cm. The radio frequency generator, air-cooled heat sink, speed-regulating motor, infrared thermometer, infrared thickness gauge, and camera are turned on simultaneously. Step 3: The electrode plates are designed in sections, with each small electrode plate having its own circuit connection to the RF generator. An electromagnetic switch is installed to individually control the operation of each small electrode plate. Each small electrode plate is adjusted via a spacing adjustment mechanism. Furthermore, the spacing between the small electrode plates and the real-time power of the RF generator are automatically adjusted based on the thickness data measured by an infrared thickness gauge. The spacing between each small electrode plate and the frozen object is individually controlled according to the size and shape of the object's outline. The camera acquires an image of the outer contour of the frozen item and controls the movement distance of the corresponding small electrode plate directly above the item based on this image. The frozen item is placed on a conveyor chain, and driven by a speed-regulating motor, the conveyor chain and the frozen items it carries enter the infeed guide cavity, thawing cavity, and outfeed guide cavity in sequence via a chain transmission mechanism. The position of the upper electrode plate and the real-time power of the radio frequency generator are automatically adjusted based on the thickness data measured by an infrared thickness gauge. When the thickness of the frozen item is greater than 8.5 cm, the upper electrode plate moves, and the moving distance is the difference between the measured thickness data and the previous measured thickness data. When the difference is positive, it moves upward; when the difference is negative, it moves downward. During the movement of the upper electrode plate, the real-time power of the corresponding radio frequency generator is automatically adjusted according to the following rules: y=kx+b y represents the real-time power of the RF generator, in kW. x is the distance between the upper and lower plates, in cm. k is the proportionality coefficient b is a constant Step 4: Adjust the conveyor speed of the conveyor chain based on the temperature value measured by the infrared thermometer. If the temperature value is lower than the set value, reduce the speed of the conveyor chain through the control system; if the temperature value is higher than the set value, increase the speed of the conveyor chain through the control system. Step 5: Repeat the steps in Step 4 until the best thawing efficiency is achieved, and weigh the frozen food after thawing to calculate the weight loss rate of the frozen food. Step Six: After the batch of frozen goods has finished thawing, turn off the radio frequency generator and the conveyor belt, delay the shutdown of the air-cooled radiator, and finally disconnect the main power supply.

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