Food freeze-drying device and control method thereof

Abstract

The invention discloses a food freeze-drying device and a control method thereof, and relates to the field of food processing instruments.The food freeze-drying device comprises a box body, a refrigeration mechanism and a freeze-drying barrel arranged in the box body, the freeze-drying barrel is provided with a freeze-drying cavity, an inner barrel and a heat preservation layer attached to the side wall of the inner barrel, and a material containing assembly used for containing materials to be processed is arranged in the freeze-drying cavity; the refrigerating mechanism comprises a cold trap arranged between the side wall of the inner barrel and the heat preservation layer, and the cold trap comprises a refrigerating pipe arranged around the side wall of the inner barrel. Due to the fact that the cold trap is arranged between the inner barrel and the heat preservation layer, the cold trap and the freeze-drying cavity are integrally arranged, during freeze-drying, moisture sublimated by materials can be captured by the cold trap and condensed on the inner wall of the freeze-drying cavity, freeze-drying dehydration is achieved, due to the fact that the cold trap and the freeze-drying cavity are integrally arranged, set functions can be achieved, the device can be simplified, and the device is high in integration degree, small in size and convenient to use. And the modern household space requirement is met, so that the household use requirement is met.

Description

Technical Field

[0001] The present invention relates to the field of food processing equipment, and particularly to a food freeze-drying device and a control method thereof. Background Art

[0002] A freeze-drying device is a device that removes moisture from materials through low-temperature freezing and vacuum sublimation. It directly converts the moisture in food from a solid state to a gaseous state for drying. Because it can retain the nutrition, flavor and structure of food to the greatest extent, it is widely loved by users.

[0003] Most of the existing freeze-drying devices are used in industry. Since the cold trap and the freeze-drying chamber are separately arranged, the refrigeration system is relatively complex. The separately arranged cold trap and freeze-drying chamber make the freeze-drying device relatively large in volume and unable to meet the household use requirements. Summary of the Invention

[0004] The present invention provides a food freeze-drying device and a control method thereof to overcome the problems of the existing freeze-drying device that the cold trap and the freeze-drying chamber are separately arranged, the refrigeration system is relatively complex, the volume is large, and it cannot meet the household use requirements.

[0005] To achieve the above object, the present invention provides the following technical solutions: A food freeze-drying device includes a box body, a refrigeration mechanism, and a freeze-drying barrel disposed in the box body. The freeze-drying barrel is provided with a freeze-drying chamber, an inner barrel, and a heat-insulating layer attached to the side wall of the inner barrel. A material placing component for placing materials to be processed is disposed in the freeze-drying chamber. The refrigeration mechanism includes a cold trap disposed between the side wall of the inner barrel and the heat-insulating layer. The cold trap includes a refrigeration pipe surrounding the side wall of the inner barrel.

[0006] For the food freeze-drying device as described above, the refrigeration mechanism further includes a condenser, a compressor, and a dryer. One end of the refrigeration pipe is connected with an intake pipe, the intake pipe is communicated with the suction port of the compressor, the exhaust port of the compressor is connected with an exhaust pipe, the other end of the exhaust pipe is communicated with the condenser, the other end of the condenser is connected with the dryer, and the other end of the dryer is communicated with the end of the refrigeration pipe far from the intake pipe.

[0007] For the food freeze-drying device as described above, the freeze-drying barrel is connected with a vacuum device. The vacuum device includes a vacuum pump and a vacuum pipe. One end of the vacuum pipe is communicated with the freeze-drying chamber, and the other end is communicated with the vacuum pump.

[0008] For the food freeze-drying device as described above, the vacuum device further includes a vacuum gauge communicated with the freeze-drying chamber and used for detecting the vacuum degree in the freeze-drying chamber. It includes a control module. The control module includes a relay module. The relay module is electrically connected with the vacuum gauge and the vacuum pump respectively.

[0009] The food freeze-drying device as described above, wherein the material placing assembly includes a material placing rack, a tray, and a pallet provided on the material placing rack, and the pallet is used to support the tray.

[0010] The food freeze-drying device as described above, wherein a heating assembly is provided at the bottom of the pallet, and the heating assembly is used to heat the material to be processed.

[0011] The food freeze-drying device as described above, wherein the freeze-drying barrel is provided with a drain pipe, and the drain pipe is communicated with the freeze-drying cavity.

[0012] The food freeze-drying device as described above includes a control module, and the control module includes a relay module, an operation screen, and a main controller. The output end of the operation screen is electrically connected to the input end of the main controller, the output end of the main controller is electrically connected to the input end of the relay module, and the output end of the relay module is respectively electrically connected to the input end of the heating assembly and the input end of the refrigeration mechanism.

[0013] A control method for a food freeze-drying device, including a food freeze-drying device, a temperature detection device, and a pressure detection device. The working modes of the food freeze-drying device include a vacuum freezing mode, a vacuum drying mode, and an additional drying mode, and the method includes the following steps: S1. Set working parameters; S2. Turn on the device, and the refrigeration mechanism pre-freezes the freeze-drying cavity. At the same time, start the preparation material countdown. The user places the material to be freeze-dried in the freeze-drying cavity. After the preparation material time arrives, go to step S3; S3. In the vacuum freezing mode, when the temperature in the freeze-drying cavity reaches the set freezing temperature, evacuate the freeze-drying cavity, and the pressure P1 in the freeze-drying cavity decreases. When the pressure P1 in the freeze-drying cavity is lower than the freeze-drying start pressure P, go to step S4; S4. In the vacuum drying mode, including a pressure mode, a pressure heating mode, and a constant temperature heating mode. First, the device enters the pressure mode and initializes the heating countdown t, starts the heating function and starts timing. At the same time, judge whether the current pressure P2 in the freeze-drying cavity is greater than the pressure P3 set in the pressure mode. If the current pressure P2 is greater than the pressure P3 set in the pressure mode, then switch to the pressure heating mode. Otherwise, judge whether the current temperature T1 in the freeze-drying cavity is greater than the set heating temperature T. If the current temperature T1 is greater than the set heating temperature T, then switch to the constant temperature heating mode. Otherwise, judge whether the heating countdown t has reached. If it has reached, stop heating, and then restart the heating countdown t. When the heating countdown t ends, initialize the heating countdown t and then start timing and heating again, and loop until the heating in the constant temperature heating mode reaches the predetermined condition, and then go to step S5; S5. In the additional drying mode, the user observes and judges the food freeze-drying state, thereby adjusting the additional drying time t1, and first set the additional drying time t1; S6. Determine whether the additional drying time t1 has been reached. If it has been reached, it is determined that the additional drying is completed and the food freeze-drying is finished. Otherwise, determine whether the current temperature T2 is less than the set heating temperature T. If it is less than, start heating, and then determine whether the current temperature T2 is greater than 1.4 °C of the set heating temperature T. If it is, stop heating, and then re-enter step S6 until the additional drying countdown time t1 ends and the freeze-drying is completed.

[0014] For the control method of the food freeze-drying device as described above, step S4 includes: S401. Set the upper pressure limit value and the lower pressure limit value. The pressure heating mode is to determine whether the current pressure P4 is greater than the set upper limit value. If it is greater, stop heating, and then determine whether the current pressure P4 is less than the set lower pressure limit. If it is less, start heating, and loop until the current temperature T3 in the freeze-drying barrel is greater than the set heating temperature T, then stop heating and enter step S402; S402. The constant temperature heating mode is to first determine whether the current temperature T4 is less than the set heating temperature T. If it is less, start heating. After heating, determine whether the current temperature T4 is greater than 1.3 °C of the set heating temperature T. If it is greater, turn off the heating, and the constant temperature heating is looped. At the same time, determine whether the pressure value is less than the drying end judgment value. If it is less, save the pressure 2 to the pressure 3, the pressure 1 to the pressure 2, and the current pressure P4 to the pressure 1. At the same time, save the values of the pressure 1, pressure 2, and pressure 3 during the cycle time, and synchronously judge and compare the difference between the pressure 1 and the pressure 2 or the pressure 3. If it is less than or equal to plus or minus 1 mtorr, it is determined that the vacuum drying is completed and enter the additional drying stage.

[0015] Compared with the prior art, the beneficial effects of the present technical solution are: 1. Since the cold trap is arranged between the inner barrel and the thermal insulation layer, and the cold trap includes a refrigeration pipe arranged around the side wall of the inner barrel, the cold trap is integrally arranged with the freeze-drying chamber. During freeze-drying, the water sublimated from the material will be captured by the cold trap and condensed on the inner wall of the freeze-drying chamber, thereby realizing freeze-drying dehydration. The integrated arrangement of the cold trap and the freeze-drying chamber can not only achieve the established function but also simplify the device, making the device have a high integration degree and a small volume, meeting the needs of modern household space, and thus meeting the family use requirements.

[0016] 2. After the user places the material to be freeze-dried in the freeze-drying chamber, the food freeze-drying device automatically enters the vacuum freezing mode. Vacuum freezing can quickly lower the temperature, causing the moisture inside the material to form a microcrystalline structure, avoiding the growth of ice crystals from damaging cells. After the freezing is completed, it enters the vacuum drying mode. After heating the material, the ice crystals directly sublimate from the solid state to the gaseous state, bypassing the liquid phase change. The gaseous water is captured by the cold trap and condensed on the inner wall of the freeze-drying chamber. After the vacuum drying is completed, it enters the additional drying mode for further drying. By raising the heating temperature and reducing the vacuum degree, the hydrogen bond connection between the bound water and the substance inside the material is broken, thereby achieving further dehydration of the material and greatly improving the freeze-drying efficiency.

[0017] 3. By pre-storing the freeze-drying formula in the control module, the user only needs to select specific freeze-drying parameters to complete the operation, without the need for the user to have professional freeze-drying knowledge to easily operate.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 is a schematic diagram of the internal structure of the present invention Figure 1 ; Figure 2 is a schematic diagram of the internal structure of the present invention Figure 2 ; Figure 3 is an exploded structural schematic diagram of the present invention; Figure 4 is a schematic diagram of the structure of the material placement component of the present invention; Figure 5 is a three-dimensional structural schematic diagram of the present invention; Figure 6 is the control principle of the present invention Figure 1 ; Figure 7 is the control principle of the present invention Figure 2 . DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] As Figures 1 to 5 shown, a food freeze-drying device includes a box body 1, a refrigeration mechanism 2, and a freeze-drying barrel 3 disposed in the box body 1. The freeze-drying barrel 3 is provided with a freeze-drying chamber 31, an inner barrel 32, and a heat-insulating layer 33 attached to the side wall of the inner barrel 32. A material placing assembly 5 for holding the material to be processed is disposed in the freeze-drying chamber 31. The refrigeration mechanism 2 includes a cold trap 23 disposed between the side wall of the inner barrel 32 and the heat-insulating layer 33. The cold trap 23 includes a refrigeration pipe 231 disposed around the side wall of the inner barrel 32. Since the cold trap 23 is disposed between the inner barrel 23 and the heat-insulating layer 33, and the cold trap 23 includes the refrigeration pipe 231 disposed around the side wall of the inner barrel 32, the cold trap 23 is integrally provided with the freeze-drying chamber 31. During freeze-drying, the water vapor sublimated from the material will be captured by the cold trap 23 and condensed on the inner wall of the freeze-drying chamber 31, thereby realizing freeze-drying dehydration. The integral setting of the cold trap 23 and the freeze-drying chamber 31 can not only achieve the predetermined function, but also simplify the device, making the device have a high integration degree and a small volume, meeting the requirements of modern home space, and thus meeting the family use requirements.

[0023] Furthermore, the box body 1 is provided with a sealing door 11 for sealing the freeze-drying chamber 31 and a feeding port communicated with the freeze-drying chamber 31. The freeze-drying barrel 3 is also provided with a sealing ring 34 corresponding to the feeding port. When the freeze-drying chamber 31 is closed, by operating the sealing door 11 to abut against the sealing ring 34, the sealing performance is better, and it is more convenient to place the material.

[0024] As a specific implementation rather than a limitation, in order to form a complete refrigeration system, the refrigeration mechanism 2 further includes a condenser 21, a compressor 22 and a dryer 25. One end of the refrigeration pipe 231 is connected with a suction pipe 232, the suction pipe 232 is communicated with the suction port of the compressor 22, the exhaust port of the compressor 22 is connected with an exhaust pipe 233, the other end of the exhaust pipe 233 is communicated with the condenser 21, the other end of the condenser 21 is connected with the dryer 25, and the other end of the dryer 25 is communicated with the end of the refrigeration pipe 231 far away from the suction pipe 232. The compressor 2 sucks the low-temperature and low-pressure refrigeration gas in the cold trap 23 through the suction pipe 232, and after being compressed by the compressor 2, discharges the high-temperature and high-pressure gas into the condenser 21. The condenser cools the high-temperature and high-pressure gaseous refrigerant into a high-pressure refrigeration liquid, and at the same time releases the heat to the outside. The high-pressure refrigeration liquid is then transported to the cold trap 23, thereby forming a cycle and forming a complete refrigeration system. The refrigeration mechanism 2 further includes a cooling fan 24 aligned with the condenser 21, and the condenser 21 is cooled by driving the cooling fan 24.

[0025] Further, in order to make the freeze-drying process in a vacuum state, the freeze-drying barrel 3 is connected with a vacuum device 7. The vacuum device 7 includes a vacuum pump 71 and a vacuum pipe 73. One end of the vacuum pipe 73 is communicated with the freeze-drying chamber 31, and the other end is communicated with the vacuum pump 71. Starting the vacuum pump 71 sucks out the air in the freeze-drying chamber 31 through the vacuum pipe 73, thereby creating a vacuum environment and enabling the material to be freeze-dried in a vacuum state.

[0026] As a specific implementation rather than a limitation, in order to detect the vacuum degree in the freeze-drying chamber 31, the vacuum device 7 further includes a vacuum gauge 72 communicated with the freeze-drying chamber 31 and used to detect the vacuum degree in the freeze-drying chamber 31. It includes a control module 8, and the control module 8 includes a relay module 81. The relay module 81 is electrically connected with the vacuum gauge 72 and the vacuum pump 71 respectively. This kind of vacuum gauge 72 is a thermocouple vacuum gauge. The vacuum gauge 72 indirectly reflects the vacuum degree by measuring the change of the gas heat conductivity in the freeze-drying chamber 31. Thus, the vacuum degree in the freeze-drying chamber 31 is detected in real time.

[0027] Further, in order to place the material, the material placing component 5 includes a material placing rack 51, a tray 52 and a tray board 53 arranged on the material placing rack 51. The tray board 53 is used to support the tray 52. A plurality of tray boards 53 are arranged on the material placing rack 51, and the tray boards 53 form multiple layers. Each tray board 53 supports a tray 52, and the tray 52 can be taken out from the material placing rack 51, which is convenient for placing the material. In addition, heat insulation boards 54 are arranged at the top and bottom of the material placing rack 51. The heat insulation boards 54 are used for heat preservation, so that the heating speed of the material in the tray 52 is faster, more uniform, and the energy loss is reduced.

[0028] As a specific embodiment, not a limitation, to heat the material, a heating assembly 6 is provided at the bottom of the support plate 53. The heating assembly 6 is used to heat the material to be processed. The heating assembly 6 is a heating patch with a temperature sensing function. The heating patch can be attached to the support plate 53. In addition, the temperature sensing function of the heating patch can provide temperature feedback, allowing for more precise heating of the material.

[0029] Furthermore, the freeze-drying barrel 3 is provided with a drain pipe 26, which communicates with the freeze-drying chamber 31. After drying is completed, a large amount of ice condenses on the inner wall of the freeze-drying chamber 31. After being heated by the heating assembly 6, the ice melts and the melted water is drained from the drain pipe 26, thereby removing the ice. The end of the drain pipe 26 away from the freeze-drying chamber 31 is also equipped with a ball valve. When it is necessary to drain the liquid in the freeze-drying chamber 31, the ball valve is simply opened, and the liquid can be discharged through the drain pipe 26.

[0030] As a specific embodiment but not limitation, it includes a control module 8, which includes a relay module 81, an operation screen 82 and a main controller 83. The output end of the operation screen 82 is electrically connected to the input end of the main controller 83, the output end of the main controller 83 is electrically connected to the input end of the relay module 81, and the output end of the relay module 81 is electrically connected to the input end of the heating component 6 and the input end of the refrigeration mechanism 2 respectively. By operating the operation screen 82 to input the preset freeze-drying parameters, the main controller 83 controls the freeze-drying device to achieve the operation of the predetermined parameters. The relay module 81 has multiple relays, and the multiple relays are electrically connected to multiple corresponding heating components 6, thereby controlling the heating component 6 to heat. Since the relay module 81 is electrically connected to the vacuum gauge 72, the vacuum pump 71, the heating mechanism 6, and the refrigeration mechanism 2 respectively, the electrical system of the freeze-drying device is highly integrated, the control is more reliable, and the volume of the freeze-drying device is significantly reduced.

[0031] The specific working principle of the present invention is: When food needs to be freeze-dried, the tray 5 is taken out, the material is evenly placed in the tray 5, and then the tray is placed on the support plate. After the sealing door 11 is closed, appropriate parameters can be selected on the control screen 82 for freeze-drying. After starting the freeze dryer, the freeze-drying chamber 31 is cooled by the cold trap 23 on the refrigeration mechanism 2 to freeze the material quickly, and the vacuum device 7 is used to evacuate the material. After the vacuum freezing is completed, the heating component 6 is used to heat the material so that the moisture in the material is directly converted from solid to gas. The gaseous water is captured by the cold trap 23 and condensed into ice and attached to the inner wall of the freeze-drying chamber 31, thereby removing the moisture in the material and achieving the freeze-drying effect.

[0032] like Figures 6 to 7A control method for a food freeze-drying device as shown, including the food freeze-drying device, temperature detection device, and pressure detection device as described. The working modes of the food freeze-drying device include a vacuum freezing mode, a vacuum drying mode, and an additional drying mode, and the method includes the following steps: S1. Set working parameters; in this application, the default pre-freezing temperature of the device is -18°C, and the temperature that the user can set is from -16°C to -28°C. The material is pre-frozen by adjusting an appropriate temperature.

[0033] S2. Turn on the device. The refrigeration mechanism 2 pre-freezes the freeze-drying chamber 31, and at the same time, start the preparation countdown. The user places the material to be freeze-dried in the freeze-drying chamber 31. After the preparation time arrives, step S3 is entered; the preparation countdown can be changed according to the actual situation by inputting a specified time to the control screen 82.

[0034] S3. In the vacuum freezing mode, when the temperature in the freeze-drying chamber 31 reaches the set freezing temperature, evacuate the freeze-drying chamber 31. The pressure P1 in the freeze-drying chamber 31 decreases. When the pressure P1 in the freeze-drying chamber is lower than the freeze-drying start pressure P, step S4 is entered; when the temperature of the freeze-drying chamber 31 drops to -18°C or the set temperature, the vacuum pump 71 is turned on to evacuate the freeze-drying chamber 31. When the pressure in the freeze-drying chamber 31 reaches 500 mtorr, it enters the vacuum drying mode.

[0035] S4. In the vacuum drying mode, it includes a pressure mode, a pressure heating mode, and a constant temperature heating mode. First, the device enters the pressure mode and initializes the heating countdown t, starts the heating function and starts timing. At the same time, it is judged whether the current pressure P2 in the freeze-drying chamber 31 is greater than the pressure P3 set in the pressure mode. If the current pressure P2 is greater than the pressure P3 set in the pressure mode, it turns to the pressure heating mode. Otherwise, it is judged whether the current temperature T1 in the freeze-drying chamber 31 is greater than the set heating temperature T. If the current temperature T1 is greater than the set heating temperature T, it turns to the constant temperature heating mode. Otherwise, it is judged whether the heating countdown t has reached. If it has reached, stop heating, and then restart the heating countdown t. When the heating countdown t ends, initialize the heating countdown t and then start timing and heating again, and perform the cycle until after heating in the constant temperature heating mode reaches the predetermined condition, step S5 is entered; The step S4 includes: As Figure 7 shown, S401. Set the pressure upper limit value and the pressure lower limit value. The pressure heating mode is to judge whether the current pressure P4 is greater than the set upper limit value. If it is greater, stop heating, and then judge whether the current pressure P4 is less than the pressure set lower limit. If it is less, start heating, and perform the cycle until the current temperature T3 in the freeze-drying barrel 31 is greater than the set heating temperature T, and then step S402 is entered; S402. In the constant-temperature heating mode, first, it is judged whether the current temperature T4 is lower than the set heating temperature T. If it is lower, heating starts. After heating, it is judged whether the current temperature T4 is higher than 1.3 °C of the set heating temperature T. If it is higher, heating is turned off, and the constant-temperature heating cycle is executed. At the same time, it is judged whether the pressure value is lower than the drying end judgment value. If it is lower, pressure 2 is saved to pressure 3, pressure 1 is saved to pressure 2, and the current pressure P4 is saved to pressure 1. At the same time, the values of pressure 1, pressure 2, and pressure 3 are saved in the cycle within the cycle time, and the difference between pressure 1 and pressure 2 or pressure 3 is synchronously judged and compared. If it is less than or equal to plus or minus 1 mtorr, it is judged that vacuum drying is completed, and the additional drying stage is entered.

[0036] In the vacuum mode, the vacuum degree in the freeze-drying chamber 31 is 10 - 30 Pa. The temperature of the heating plate can be increased in a gradient from -20 °C to +60 °C. The vacuum pump 71 pumps out the air in the freeze-drying chamber 31, reducing its air pressure to below 611.73 Pa, the triple point of water. The ice crystals in the material directly sublimate from the solid state to the gaseous state, bypassing the liquid phase change. The pressure in the freeze-drying chamber 31 is controlled within the range of 350 - 650 mtorr, and drying is carried out by intermittent compensated heating sublimation; the gaseous water is captured by the -45 °C cold trap 23, and the gaseous water solidifies on the inner wall of the freeze-drying chamber. In vacuum drying, the sublimation rate is inversely proportional to the square of the material thickness. Preferably, the material thickness is controlled <= 15 mm, and the material temperature is maintained below the collapse temperature.

[0037] S5. In the additional drying mode, the user observes and judges the freeze-drying state of the food to adjust the additional drying time t1, and first sets the additional drying time t1; in addition, when judging whether the food has reached the freeze-dried state, a camera can be set. The camera is connected to the computer terminal, and the photos are transmitted to the computer terminal through the camera for deep learning matching. In the computer terminal, the openCV software can be used for processing. First, photos of the freeze-dried state of the food are collected and input into the computer for deep learning. It can be selected to iterate 8000 - 10000 times to obtain a relatively stable model, and then the photos transmitted back by the camera are feature-matched with the generated model to obtain the freeze-dried state of the food, and then the additional drying time t1 is set according to the freeze-dried state of the food.

[0038] S6. Determine whether the additional drying time t1 has reached. If it has reached, it is determined that the additional drying is completed and the food freeze-drying is finished. Otherwise, determine whether the current temperature T2 is lower than the set heating temperature T. If it is lower, start heating. Then, determine whether the current temperature T2 is higher than 1.4 °C of the set heating temperature T. If so, stop heating. Subsequently, re-enter step S6 until the additional drying countdown time t1 ends, then the freeze-drying is completed. In the additional drying mode, the temperature is controlled within the range of +45 °C ± 55 °C, and the vacuum is further reduced to about 20 Pa, thereby breaking the hydrogen bond connection between the bound water and the substance inside the material. After the ice crystals sublime, a porous structure is left, and the rehydration rate > 95%. The low-temperature operation can enable the retention rate of heat-sensitive substances such as vitamin C > 97%. The vacuum environment can inhibit the microbial activity, making the water activity Aw < 0.6.

[0039] This freeze-drying device also has functions of refrigeration alarm, heating alarm, pressure alarm, power supply alarm, and defrosting. Defrosting function: After the freeze-drying is completed, the water vapor captured by the cold trap 23 will freeze on the inner wall of the freeze-drying chamber 31 to form a large number of ice cubes. The defrosting function can be selected through the control panel 82. The defrosting function is to control the heating component 6 to heat by the main controller 83 controlling the relay module 81, so as to increase the temperature inside the freeze-drying chamber 31. After the temperature inside the freeze-drying chamber 31 rises, the ice cubes on the inner wall of the freeze-drying chamber 31 can be quickly melted, thus achieving the purpose of defrosting. The defrosting heating temperature is controlled within the range of 50 °C - 60 °C. Timed defrosting can also be set, and the defrosting duration can be adjusted during the defrosting process.

[0040] In this freeze-drying device, for the processing of candies, a candy mode is also set. By reducing the temperature inside the freeze-drying chamber 31 below 0 °C, then controlling the heating temperature within the range of 54 °C - 75 °C, and then quickly evacuating the air and heating in a low-temperature environment, the moisture in the candies can be quickly evaporated. After the moisture evaporates, a large number of tiny voids will be formed inside the candies, resulting in volume expansion.

[0041] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. A food freeze-drying device, comprising a box body (1), a refrigeration mechanism (2), and a freeze-drying barrel (3) disposed inside the box body (1), characterized in that, The freeze-drying barrel (3) is provided with a freeze-drying chamber (31), an inner barrel (32), and a heat-insulating layer (33) disposed along the side wall of the inner barrel (32). A material placing assembly (5) for holding the material to be processed is arranged in the freeze-drying chamber (31). The refrigeration mechanism (2) includes a cold trap (23) disposed between the side wall of the inner barrel (32) and the heat-insulating layer (33). The cold trap (23) includes a refrigeration pipe (231) surrounding the side wall of the inner barrel (32).

2. The food freeze-drying device according to claim 1, characterized in that, The refrigeration mechanism (2) further includes a condenser (21), a compressor (22), and a dryer (25). One end of the refrigeration pipe (231) is connected with a suction pipe (232). The suction pipe (232) is communicated with the suction port of the compressor (22). The exhaust port of the compressor (22) is connected with an exhaust pipe (233). The other end of the exhaust pipe (233) is communicated with the condenser (21). The other end of the condenser (21) is connected with the dryer (25). The other end of the dryer (25) is communicated with the end of the refrigeration pipe (231) far away from the suction pipe (232).

3. The food freeze-drying device according to claim 1, characterized in that, The freeze-drying barrel (3) is connected with a vacuum device (7). The vacuum device (7) includes a vacuum pump (71) and a vacuum pipe (73). One end of the vacuum pipe (73) is communicated with the freeze-drying chamber (31), and the other end is communicated with the vacuum pump (71).

4. The food freeze-drying device according to claim 3, wherein, The vacuum device (7) further includes a vacuum gauge (72) communicated with the freeze-drying chamber (31) and used for detecting the vacuum degree in the freeze-drying chamber (31). It includes a control module (8). The control module (8) includes a relay module (81). The relay module (81) is electrically connected with the vacuum gauge (72) and the vacuum pump (71) respectively.

5. The food freeze-drying device according to claim 1, wherein The material placing assembly (5) includes a material placing rack (51), a tray (52), and a tray board (53) arranged on the material placing rack (51). The tray board (53) is used for supporting the tray (52).

6. The food freeze-drying device according to claim 5, wherein, A heating assembly (6) is arranged at the bottom of the tray board (53). The heating assembly (6) is used for heating the material to be processed.

7. The food freeze-drying device according to claim 1, characterized in that, The freeze-drying barrel (3) is provided with a drain pipe (26). The drain pipe (26) is communicated with the freeze-drying chamber (31).

8. The food freeze-drying device according to claim 6, wherein It includes a control module (8). The control module (8) includes a relay module (81), an operation screen (82), and a main controller (83). The output end of the operation screen (82) is electrically connected with the input end of the main controller (83). The output end of the main controller (83) is electrically connected with the input end of the relay module (81). The output end of the relay module (81) is electrically connected with the input ends of the heating assembly (6) and the refrigeration mechanism (2) respectively.

9. A control method for a food freeze-drying device, comprising the food freeze-drying device, a temperature detection device, and a pressure detection device as described in any one of claims 1-8, wherein the working modes of the food freeze-drying device include a vacuum freezing mode, a vacuum drying mode, and an additional drying mode, characterized in that, It includes the following steps: S1. Set working parameters; S2. Turn on the device. The refrigeration mechanism (2) pre-freezes the freeze-drying chamber (31), and at the same time starts the preparation material countdown. The user places the material to be freeze-dried in the freeze-drying chamber (31). After the preparation material time arrives, it enters step S3; S3. In the vacuum freezing mode, after the temperature in the freeze-drying chamber (31) reaches the set freezing temperature, evacuate the freeze-drying chamber (31), and the pressure P1 in the freeze-drying chamber (31) decreases. When the pressure P1 in the freeze-drying chamber (31) is lower than the freeze-drying start pressure P, proceed to step S4; S4. In the vacuum drying mode, including the pressure mode, the pressure heating mode, and the constant temperature heating mode, first, the device enters the pressure mode and initializes the heating countdown t, starts the heating function and begins timing. At the same time, determine whether the current pressure P2 in the freeze-drying chamber (31) is greater than the pressure P3 set in the pressure mode. If the current pressure P2 is greater than the pressure P3 set in the pressure mode, switch to the pressure heating mode. Otherwise, determine whether the current temperature T1 in the freeze-drying chamber (31) is greater than the set heating temperature T. If the current temperature T1 is greater than the set heating temperature T, switch to the constant temperature heating mode. Otherwise, determine whether the heating countdown t has reached. If it has reached, stop heating, then restart the heating countdown t. When the heating countdown t ends, initialize the heating countdown t and then start timing and heating again, repeating the cycle until heating in the constant temperature heating mode reaches the predetermined condition, and then proceed to step S5; S5. In the additional drying mode, the user observes and judges the freeze-drying state of the food, thereby adjusting the additional drying time t1, and first sets the additional drying time t1; S6. Determine whether the additional drying time t1 has reached. If it has reached, judge that the additional drying is over and the food freeze-drying is completed. Otherwise, determine whether the current temperature T2 is less than the set heating temperature T. If it is less than, start heating, and then determine whether the current temperature T2 is greater than 1.4 °C of the set heating temperature T. If it is, stop heating, and then re-enter step S6 until the additional drying time t1 ends and the freeze-drying is completed.

10. The control method of the food freeze-drying device according to claim 9, characterized in that, The said step S4 includes: S401. Set the pressure upper limit value and the pressure lower limit value. In the pressure heating mode, determine whether the current pressure P4 is greater than the set upper limit value. If it is greater, stop heating, and then determine whether the current pressure P4 is less than the pressure set lower limit. If it is less, start heating, and repeat the cycle until the current temperature T3 in the freeze-drying chamber (31) is greater than the set heating temperature T, then stop heating and enter step S402; S

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