Control method of superheated steam air fryer

Abstract

The invention relates to a control method of a superheated steam air fryer, and aims to solve the technical problems that the non-enzymatic browning temperature of food materials is difficult to accurately control through control of a superheated evaporator in the superheated steam cooking process of existing similar products, and the steamed flavor is not lost due to non-enzymatic browning. The control method is characterized by comprising a temperature rise stage, a duty ratio temperature control stage and an overtemperature stage, when water does not enter the load at the temperature rising stage, the NTC T of the evaporator in the cavity is smaller than or equal to T1, the heating pipe of the evaporator is 5 / 5, the water pump is 0 / 1.6, the mosquito-repellent incense pipe is 3 / 30, and the motor is low in speed; when the load begins to feed water at a temperature rise stage, NTC of the evaporator in the cavity is that T1 < T < = T2, the heating tube of the evaporator is 5 / 5, the water pump is N1 / 1.6, the mosquito-repellent incense tube is 3 / 30, and the motor is at a low speed; in the duty ratio temperature control stage, water is fed periodically, the target temperature control temperature of the evaporator NTC is T3 + / -5 DEG C, the mosquito-repellent incense tube is 1 / 30, and the motor is low in speed.

Description

Technical Field

[0001] This invention relates to a steam air fryer, specifically a method for controlling a superheated steam air fryer. Background Technology

[0002] An air fryer is a new type of household appliance that uses high-speed air circulation technology to fry food. Food cooked in an air fryer contains up to 80% less oil than food cooked in a traditional fryer. It is easy to clean in daily use, and is both safe and economical, making it very popular. Some air fryers now incorporate a steam function, called steam air fryers. These are appliances that combine the functions of an air fryer and a steam oven, but require a higher level of steam tightness. Their core technology involves adding a water tank, water pump, steam generator, and nozzles to the basic air fryer design. Currently, the application of steam generators in the air fryer industry is as follows: 1. Industry Status: In recent years, as consumers have placed higher demands on the taste of cooking and healthy eating, the market share of steam air fryers has jumped from 1.38% in 2022 to 14.38% in 2023, further exceeding 51.33% in 2024, and reaching as high as 63.44% in the first quarter of 2025; 2. Industry Technology: Currently, research on how to accurately control the temperature and amount of superheated steam in flow channel steam generators to maximize their advantages is still in its infancy; 3. Steam Cooking: Regarding the non-enzymatic browning temperature of food, superheated steam cooking generally begins to slowly undergo non-enzymatic browning at 110℃, and only at 140-160℃ does a violent Maillard reaction occur.

[0003] The aforementioned steam generator, or simply evaporator, produces superheated steam with advantages such as high temperature, rapid heat transfer, and high dryness. However, it also easily causes surface moisture on food to boil and evaporate quickly, resulting in a reduced surface moisture. Therefore, when using superheated steam, it is crucial to utilize its advantages while preventing non-enzymatic browning of the food, which would cause it to lose its steamed flavor. This requires a high level of temperature control. The essence of cooking is to drive physical and chemical changes in food through energy exchange, thereby making the food delicious and safe. Existing steam air fryers of this type have structural designs and temperature control methods, such as Chinese patent application number 202411334071.5, published on November 26, 2024, entitled "A cooking appliance superheated steam system and its temperature control method"; however, in the temperature control methods of the above-mentioned products and similar products, the water pump control cycle is 1 second, the water pump control speed is relatively fast, and the water pump lacks a method design that allows the first 16 units of each cycle to operate with a duty cycle of N2 / 1.6 and the last 16 units to operate with a duty cycle of N3 / 1.6. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings, the purpose of this invention is to provide a superheated steam air fryer and its control method, thereby solving the technical problems of existing similar cooking appliances that have difficulty in accurately controlling the temperature and amount of superheated steam in the heating element of the superheated evaporator, and that have difficulty in accurately controlling the non-enzymatic browning temperature of food during superheated steam cooking, thus avoiding the loss of steamed flavor due to non-enzymatic browning. This objective is achieved through the following technical solution.

[0005] A control method for a superheated steam air fryer, comprising an integrated superheated evaporator, a water pump, a motor, a coil tube, a stirring fan, and a shell. An evaporator NTC (Non-Temperature Temperature Sensor) is housed within a cavity formed by a metal insulation layer at the coil tube and the pot body within the lower internal metal lining. The integrated superheated evaporator contains an integrated heating tube and a steam tube within an aluminum block. The heating tube is positioned within a centrally curved and overlapping steam tube. Water in the steam tube is converted into 300°C superheated steam by the integrated superheated evaporator. The steam tube extends from both ends of the aluminum block, connecting to a water inlet and a steam outlet, respectively. The evaporator heating tube of the unit has two terminals extending from one side of the aluminum block. At least one temperature controller is installed on the outer diameter of the aluminum block between the water inlet and steam outlet of the evaporator steam tube. Another NTC temperature sensor is installed on the aluminum block at one end of the steam outlet of the evaporator steam tube. The mosquito coil tube is the heating element. A stirring fan is installed in the groove of the metal insulation layer above the mosquito coil tube. The stirring fan is connected to the motor shaft of a motor that extends into the metal insulation layer. The motor is located in the motor slot of the plastic insulation layer at the top of the metal insulation layer. The water inlet pipe is connected to the water outlet of the water tank via a water pump, connecting pipe, and water tank valve assembly. The terminals of the motor, mosquito coil tube, water pump, and evaporator heating tube of the integrated superheated evaporator are connected to the PCB control assembly via wiring. The pot body is inserted through an opening on one side of the unit body below the metal insulation layer. The key structural design feature is that the evaporator heating tube of the integrated superheated evaporator switches on and off in a 5-second cycle. The evaporator heating tube control of the integrated superheated evaporator is based on the following formula.

[0006] Formula a

[0007] In formula a, k is the sampling number, k = 0, 1, 2, ...; u k e is the computer output value at the k-th sampling time; k e is the deviation value input at the k-th sampling time; k-1 Ki is the deviation value input at the (k-1)th sampling time; Ki is the integration coefficient, Ki=k p *T / Ti; Kd is the differential coefficient, Kd=k p*Td / T; This formula automatically calculates the duty cycle of the evaporator heating tubes in the integrated superheated evaporator, ensuring that the integrated superheated evaporator maintains a constant temperature.

[0008] The water pump inlet control: Formula b

[0009] In formula b, t represents time in seconds; 1.6 represents the water intake cycle of 1.6 seconds; N1, N2, N3, and N4 represent the water intake time within the cycle, with N4 > N3 > N2 > N1; 1.5 ≤ N2 / N3 ≤ 2 (N2 > N3): This is mainly to prevent non-enzymatic browning of the food surface due to prolonged high temperatures; mod represents the remainder function, which is a step function; where N2 / 1.6 is used to allow the food to quickly absorb the energy of the superheated steam; and N3 / 1.6 is used to prevent the food surface temperature from becoming too high, thus preventing non-enzymatic browning.

[0010] The control method includes a heating phase, a duty cycle temperature control phase, and an over-temperature phase. The heating phase includes no water intake and water intake start-up. When the load is in the heating phase without water intake, the evaporator NTC is T≤T1, the evaporator heating element is 5 / 5, the water pump is 0 / 1.6, the mosquito coil tube is 3 / 30, and the motor is at low speed. When the load is in the heating phase with water intake start-up, the evaporator NTC is T1<T≤T2, the evaporator heating element is 5 / 5, and the water pump is N1 / 1. 0.6, the mosquito coil tube is 3 / 30, and the motor is at low speed; during the duty cycle temperature control stage, water is introduced periodically, the target temperature control temperature of the evaporator NTC is T3±5℃, the evaporator heating tube is according to the above formula a, the water pump is according to the above formula b, the mosquito coil tube is 1 / 30, and the motor is at low speed; during the over-temperature stage, the evaporator NTC is T>T4, the evaporator heating tube is in the off state, the water pump is N4 / 1.6, the mosquito coil tube is in the off state, and the motor is at low speed.

[0011] The evaporator steam pipe of the integrated superheated evaporator has a waist-shaped bend in the middle and the middle pipe is wrapped and the distance between the pipes is controlled to be more than 2mm. The waist-shaped hole in the center of the middle pipe is equipped with an evaporator heating pipe integrally formed with the evaporator steam pipe by an aluminum block. The water in the evaporator steam pipe is first heated to 100°C superheated steam by the evaporator heating pipe, and then heated to 300°C superheated steam.

[0012] The connectors at both ends of the evaporator heating tube of the integrated superheated evaporator are offset from the water inlet and steam outlet at both ends of the evaporator steam tube, extending out of the aluminum block. The section of the evaporator heating tube with a ring or waist-shaped bend inside the evaporator steam tube is the heating part, and the section of the evaporator heating tube extending out of the aluminum block after the bend inside the evaporator steam tube is the non-heating part. The aluminum block and the evaporator steam tube on the side of the aluminum block closest to the water inlet are the part with the highest energy, and the symmetrical side on the other side of the connectors at both ends of the evaporator heating tube is the part with gradually increasing temperature.

[0013] Another evaporator NTC is provided on one side of the outer diameter of the aluminum block on the side of the evaporator steam pipe inlet of the integrated superheated evaporator. The NTC temperature sensor is located near the highest energy part of the evaporator steam pipe and the distance between it and the outer diameter of the aluminum block on that side is ≤5mm. The distance between the evaporator NTC at the steam port end of the evaporator steam pipe and the outer diameter of the aluminum block on that side is 15-20mm.

[0014] The water inlet and steam outlet at both ends of the evaporator steam pipe of the integrated superheated evaporator extend outward along the winding direction and are offset from the unheated part of the evaporator heating pipe extending out of the aluminum block, or they curve outward at 90 degrees to the outside of the two side openings and are offset from the unheated part of the heating pipe extending out of the aluminum block.

[0015] The aluminum block of the integrated superheated evaporator has regular or irregular low-thickness wrapping grooves on both sides of its outer diameter, which are symmetrically arranged below the plane. Two temperature controllers are respectively set at the low-thickness wrapping grooves or on the outer plane of the low-thickness wrapping grooves.

[0016] A cross-flow fan is installed inside the plastic insulation layer on top of the metal insulation layer above the stirring fan blade. The motor shaft of the motor is connected to both the stirring fan blade and the cross-flow fan blade. The worm gear channel on one side of the plastic insulation layer is connected to the exhaust hood of the outer casing.

[0017] The evaporator NTC is located on one side of the groove in the metal insulation layer.

[0018] The present invention has a reasonable structural design, is easy to install and use, has good temperature control and sensing effect, and has a wide range of applications. In particular, the NTC temperature sensor is installed in a reasonable position, and the control method of the evaporator heating tube and water pump of the integrated superheated evaporator is scientific and precise, effectively avoiding non-enzymatic browning of food and preserving the flavor of steamed food. It is suitable for use as a control method for superheated steam air fryers, as well as for structural improvements of similar products. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the working principle of the integrated superheated evaporator in an embodiment of the present invention. The arrows in the diagram represent the water passage and the steam passage, respectively.

[0020] Figure 2 yes Figure 1 A schematic diagram of the three-dimensional structure.

[0021] Figure 3 yes Figure 2 The diagram shows an enlarged view of the integrated superheated evaporator and the internal structure of the compressor head. The dotted lines in the diagram represent the internal structure of the integrated superheated evaporator.

[0022] Figure 4 yes Figure 3An enlarged structural diagram of the other side of the integrated superheated evaporator.

[0023] Figure 5 The steps of the superheated steam control algorithm of the present invention are as follows.

[0024] Figure 6 This is the control curve of NTC density and temperature in the evaporator of the present invention.

[0025] Attached figures and their names: 1. Integrated superheated evaporator; 101. Evaporator heating tube; 102. Evaporator steam tube; 2. Water pump; 3. Water inlet pipe; 4. Evaporator NTC; 5. Thermostat; 6. Steam tube; 7. Motor; 8. Plastic insulation layer; 9. Connecting pipe; 10. Mosquito coil tube; 11. Stirring fan blade; 12. Cross-flow fan blade. Detailed Implementation

[0026] The structure and use of the present invention will now be further described with reference to the accompanying drawings. Figures 1-6 As shown, the superheated steam air fryer includes an integrated superheated evaporator 1, a water pump 2, a motor 7, a mosquito coil tube 10, a stirring fan, and a shell. An evaporator NTC 4 is housed within the cavity formed by the metal insulation layer at the mosquito coil tube and the pot body in the lower internal hardware lining. The NTC evaporator is an NTC temperature sensor. An integrated evaporator heating tube 101 and an evaporator steam tube 102 are integrated within the aluminum block of the integrated superheated evaporator. The evaporator heating tube is located within the evaporator steam tube, which is bent in a waist shape and coiled in the middle. Water in the evaporator steam tube is converted into 300°C superheated steam through the integrated superheated evaporator. The two ends of the evaporator steam tube extend from the aluminum block, connecting to the water inlet 3 and the steam pipe 6 respectively. Two terminals of the evaporator heating tube extend out from one side of the aluminum block. At least one thermostat 5 is provided on the outer diameter of the aluminum block between the water inlet and the steam outlet of the evaporator steam tube. Another NTC temperature sensor is provided on the aluminum block at one end of the steam outlet of the evaporator steam tube. The mosquito coil tube is a heating tube. A stirring fan 11 is provided in the groove of the metal insulation layer above the mosquito coil tube. The stirring fan is connected to the motor shaft of the motor that extends into the metal insulation layer. The motor is located in the motor slot of the plastic insulation layer 8 in the top of the metal insulation layer. The water inlet pipe is connected to the water outlet of the water tank in sequence through the water pump, connecting pipe 9, and water tank valve body assembly. The terminals of the motor, mosquito coil tube, water pump, and evaporator heating tube of the integrated superheated evaporator are connected to the PCB control assembly through wiring. The pot body is placed in the opening on one side of the body below the metal insulation layer.

[0027] In the aforementioned integrated superheated evaporator, the distance between the intermediate tubes, which are bent in a waist shape and intertwined, is controlled to be more than 2mm. An evaporator heating tube, integrally formed with the evaporator steam tube by an aluminum block, is located within the waist-shaped hole at the center of the intermediate tube. Water in the evaporator steam tube is first heated to 100℃ superheated steam by the evaporator heating tube, and then reheated to 300℃ superheated steam. The connectors at both ends of the evaporator heating tube extend out of the aluminum block, offset from the water inlet and steam outlet at both ends of the evaporator steam tube. The section of the evaporator heating tube within the evaporator steam tube that is in a ring or waist-shaped bend is the heating section, while the section extending out of the evaporator heating tube from the bent aluminum block is the non-heating section. The aluminum block and the evaporator steam tube on the side closest to the water inlet within the aluminum block represent the highest energy level, while the symmetrical side extending from the connectors at both ends of the evaporator heating tube represents the section where the temperature gradually increases. Another evaporator NTC is installed on the outer diameter side of the aluminum block on one side of the evaporator steam pipe inlet of the integrated superheated evaporator. The temperature sensor of the NTC is located near the highest energy part of the evaporator steam pipe, and the distance between it and the outer diameter of the aluminum block on that side is ≤5mm. The distance between the evaporator NTC at the steam port end of the evaporator steam pipe and the outer diameter of the aluminum block on that side is 15-20mm.

[0028] Furthermore, in the aforementioned integrated superheated evaporator, the water inlet and steam outlet at both ends of the evaporator steam pipe extend outwards along the winding direction, offset from the non-heated portion of the evaporator heating pipe extending from the aluminum block, or curve outwards at a 90-degree angle to the outside of the two side openings, offset from the non-heated portion of the heating pipe extending from the aluminum block. The outer diameter of the aluminum block of the integrated superheated evaporator is provided with regular or irregular low-thickness wrapping grooves symmetrically arranged on both sides below the plane. Two thermostats are respectively located at the low-thickness wrapping grooves or on the outer plane of the low-thickness wrapping grooves.

[0029] Furthermore, a cross-flow fan 12 is provided within the plastic insulation layer on top of the metal insulation layer above the aforementioned stirring fan. The motor shaft of the motor is connected to both the stirring fan and the cross-flow fan. The worm gear channel on one side of the plastic insulation layer is connected to the exhaust hood of the outer casing. The evaporator NTC is located within a groove on one side of the metal insulation layer.

[0030] The control method of this superheated steam air fryer is based on thermodynamic characteristics. By precisely controlling the superheated steam parameters, the superheated steam can quickly complete the cooking process while preserving the flavor of the steamed food.

[0031] The specific product structure and control method of this superheated steam air fryer are as follows:

[0032] I. Product Structure:

[0033] This superheated steam air fryer mainly consists of an integrated superheated evaporator, a water pump, a shaded pole motor, a stirring fan, a mosquito coil tube, and an outer shell. The integrated superheated evaporator turns water into 300°C superheated steam. The water pump draws water from the water tank into the integrated superheated evaporator. The shaded pole motor provides power to the stirring fan. The fan ensures that the steam is evenly distributed within the cavity. The mosquito coil tube transfers energy into the cavity primarily through forced convection.

[0034] II. Control methods:

[0035] Evaporator heating element control for integrated superheated evaporators:

[0036] In the formula, k is the sampling sequence number, k = 0, 1, 2, ...; u k e is the computer output value at the k-th sampling time; k e is the deviation value input at the k-th sampling time; k-1 Ki is the deviation value input at the (k-1)th sampling time; Ki is the integration coefficient, Ki=k p *T / Ti; Kd is the differential coefficient, Kd=k p *Td / T; This formula automatically calculates the duty cycle of the evaporator heating tubes in the integrated superheated evaporator, ensuring that the integrated superheated evaporator maintains a constant temperature.

[0037] Water pump inlet control:

[0038] In the formula, t represents time in seconds; 1.6 represents the water intake cycle of 1.6 seconds; N1, N2, N3, and N4 represent the water intake time within the cycle, with N4 > N3 > N2 > N1; 1.5 ≤ N2 / N3 ≤ 2 (N2 > N3): This is mainly to avoid non-enzymatic browning of the food surface due to prolonged high temperatures; mod represents the remainder function, which is a step function; executing N2 / 1.6 is to allow the food to quickly absorb the energy of the superheated steam; executing N3 / 1.6 is to prevent the food surface temperature from becoming too high, thus avoiding non-enzymatic browning.

[0039] Other parameters: T4 > T3 > T2 > T1; 5 / 5: The evaporator heating element of the integrated superheated evaporator operates on a 5-second cycle, with the heating element on for 5 seconds within the cycle; OFF: The heating element is off; 3 / 30: The mosquito coil tube operates on a 30-second cycle, with the heating element on for 5 seconds within the cycle; 1 / 30: The mosquito coil tube operates on a 30-second cycle, with the heating element on for 1 second within the cycle; Motor at low speed: The higher the temperature, the lower the steam density; This prevents excessive pressure inside the cavity from causing leakage; It also promptly removes low-quality steam from the cavity to avoid affecting the cooking effect.

[0040] In summary, the steps of the above control method are as follows:

[0041] The evaporator NTC divides the load into a heating stage, a duty cycle temperature control stage, and an over-temperature stage based on the detected temperature.

[0042] During the heating phase, when the detected temperature T≤T1, the evaporator heating tube is controlled to run continuously at full power, and the water pump does not work; when the detected temperature T1<T≤T2, the evaporator heating tube is controlled to maintain full power operation, and the water pump is controlled to start water intake with a duty cycle of N1 / 1.6.

[0043] During the duty cycle temperature control phase, based on the target temperature T3±5℃, a PID algorithm is used to control the operating duty cycle of the evaporator heating tubes. The control quantity is:

[0044]

[0045] Meanwhile, the water pump operates in a periodic duty cycle mode, specifically: in each cycle of 32 units, the first 16 units operate with a duty cycle of N2 / 1.6, and the last 16 units operate with a duty cycle of N3 / 1.6.

[0046] During the over-temperature stage, when the detected temperature T > T4, the evaporator heating tube is controlled to stop working, and the water pump is controlled to run with a duty cycle of N4 / 1.6.

[0047] Throughout the control process, the mosquito coil tube operates with a corresponding duty cycle depending on the different operating stages, while the motor always runs at a low speed.

[0048] The above description is intended to illustrate the technical means of the present invention and is not intended to limit the scope of the invention. Any obvious improvements or substitutions made to the present invention by those skilled in the art based on existing common knowledge also fall within the protection scope of the claims of the present invention. For example, according to the prior art, the steam fryer uses a steam fryer with a separate steam function, or a double-cavity steam fryer of the same size or different sizes, with a steam function on one side and an air-frying function on the other side, and employs a single fan blade structure design.

Claims

1. A control method for a superheated steam air fryer, the superheated steam air fryer comprising an integrated superheated evaporator (1), a water pump (2), a motor (7), a mosquito coil tube (10), a stirring fan, and a shell, wherein an evaporator NTC is provided in the cavity formed by the metal heat insulation layer at the mosquito coil tube and the pot body at the fryer assembly in the lower internal hardware lining. (4) The evaporator NTC is an NTC temperature sensor. The aluminum block of the integrated superheated evaporator is equipped with an integrally formed evaporator heating tube (101) and evaporator steam tube (102). The evaporator heating tube is set inside the evaporator steam tube, which is bent in the middle and overlapped. The water in the evaporator steam tube is turned into 300°C superheated steam through the integrated superheated evaporator. The two ends of the evaporator steam tube of the integrated superheated evaporator extend out of the water inlet and steam outlet of the aluminum block respectively and are connected to the water inlet pipe (3) and steam pipe (6) respectively. The two terminals of the evaporator heating tube of the integrated superheated evaporator extend out of one side of the aluminum block at the same time. The outer diameter of the aluminum block between the water inlet and steam outlet of the evaporator steam tube is provided with at least A thermostat (5), and another NTC temperature sensor is provided on the aluminum block at one end of the steam port of the evaporator steam pipe; the mosquito coil tube is a heating tube, and a stirring fan (11) is provided in the groove of the metal insulation layer above the mosquito coil tube. The stirring fan is connected to the motor shaft of the motor (7) that extends into the metal insulation layer. The motor is located in the motor slot of the plastic insulation layer (8) in the top of the metal insulation layer; the water inlet pipe is connected to the water outlet of the water tank in sequence through the water pump, the connecting pipe (9), and the water tank valve body assembly. The wiring terminals of the motor, the mosquito coil tube, the water pump, and the evaporator heating tube of the integrated superheated evaporator are connected to the PCB control assembly through the wiring. The pot body is placed in the opening on one side of the body below the metal insulation layer; characterized in that The evaporator heating tube (101) of the integrated superheated evaporator (1) switches on and off in a 5-second cycle. The evaporator heating tube of the integrated superheated evaporator is controlled according to the following formula. Official A In formula a, k is the sampling number, k = 0, 1, 2, ...; u k e is the computer output value at the k-th sampling time; k e is the deviation value input at the k-th sampling time; k-1 Ki is the deviation value input at the (k-1)th sampling time; Ki is the integration coefficient, Ki=k p *T / Ti; Kd is the differential coefficient, Kd=k p *Td / T; This formula automatically calculates the duty cycle of the evaporator heating tubes in the integrated superheated evaporator, ensuring that the integrated superheated evaporator maintains a constant temperature. Water pump (2) inlet control: Formula b In formula b, t represents time in seconds; 1.6 represents the water intake cycle of 1.6 seconds; N1, N2, N3, and N4 represent the water intake time within the cycle, with N4 > N3 > N2 > N1; and mod represents the remainder function, which is a step function.

2. The control method for the superheated steam air fryer according to claim 1, characterized in that... The control method includes a heating stage, a duty cycle temperature control stage, and an over-temperature stage. The heating stage includes no water intake and water intake start. When the load is in the heating stage without water intake, the NTC (4) of the evaporator in the cavity is T≤T1, the evaporator heating tube is 5 / 5, the water pump (2) is 0 / 1.6, the mosquito coil tube (10) is 3 / 30, and the motor (7) is at low speed. When the load is in the heating stage with water intake start, the NTC of the evaporator in the cavity is T1<T≤T2, and the evaporator heating tube is 5 / 5. The water pump is N1 / 1.6, the mosquito coil tube is 3 / 30, and the motor is at low speed. During the duty cycle temperature control stage, water is introduced periodically, the target temperature control temperature of the evaporator NTC is T3±5℃, the evaporator heating tube is as described in formula a above, the water pump is as described in formula b above, the mosquito coil tube is 1 / 30, and the motor is at low speed. During the over-temperature stage, the evaporator NTC in the cavity is T>T4, the evaporator heating tube is in the off state, the water pump is N4 / 1.6, the mosquito coil tube is in the off state, and the motor is at low speed.

3. The control method for the superheated steam air fryer according to claim 1, characterized in that... The evaporator steam pipe (102) of the integrated superheated evaporator (1) has a waist-shaped bend in the middle and the distance between the pipes is controlled to be more than 2mm. The waist-shaped hole in the center of the middle pipe is provided with an evaporator heating pipe (101) integrally formed with the evaporator steam pipe by an aluminum block. The water in the evaporator steam pipe is first heated to 100°C superheated steam by the evaporator heating pipe, and then heated to 300°C superheated steam a second time.

4. The control method for the superheated steam air fryer according to claim 3, characterized in that... The evaporator heating tube (101) of the integrated superheated evaporator (1) has its terminals at both ends offset from the water inlet and steam outlet at both ends of the evaporator steam tube (102) by an aluminum block. The section of the evaporator heating tube with a ring or waist-shaped bend inside the evaporator steam tube is the heating part, and the section of the evaporator heating tube extending from the aluminum block after the bend inside the evaporator steam tube is the non-heating part. The aluminum block and the evaporator steam tube on the side of the aluminum block closest to the water inlet are the parts with the highest energy, and the other side symmetrical to the terminals at both ends of the evaporator heating tube is the part with gradually increasing temperature.

5. The control method for the superheated steam air fryer according to claim 4, characterized in that... The integrated superheated evaporator (1) has another evaporator NTC (4) on the outer diameter side of the aluminum block on the side of the water inlet of the evaporator steam pipe (102). The NTC temperature sensor is located near the highest energy part of the evaporator steam pipe and the distance between it and the outer diameter of the aluminum block on that side is ≤5mm. The distance between the evaporator NTC at the steam port end of the evaporator steam pipe and the outer diameter of the aluminum block on that side is 15-20mm.

6. The control method for the superheated steam air fryer according to claim 1, characterized in that... The water inlet and steam outlet at both ends of the evaporator steam pipe (102) of the integrated superheated evaporator (1) extend outward along the winding direction and are offset from the unheated part of the evaporator heating pipe (101) extending out of the aluminum block, or they curve outward at 90 degrees to the outside of the two side openings and are offset from the unheated part of the heating pipe extending out of the aluminum block.

7. The control method for the superheated steam air fryer according to claim 1, characterized in that... The integrated superheated evaporator (1) has regular or irregular low-thickness wrapping grooves on both sides of the outer diameter of the aluminum block, which are symmetrically arranged below the plane. The two temperature controllers (5) are respectively set at the low-thickness wrapping groove or on the outer plane of the low-thickness wrapping groove.

8. The control method for the superheated steam air fryer according to claim 1, characterized in that... A cross-flow fan (12) is provided inside the plastic insulation layer (8) on top of the metal insulation layer above the stirring fan (11). The motor shaft of the motor (7) is connected to both the stirring fan and the cross-flow fan. The worm gear channel on one side of the plastic insulation layer is connected to the exhaust hood of the outer shell.

9. The control method for the superheated steam air fryer according to claim 1, characterized in that... The evaporator NTC (4) is located on one side of the groove in the metal insulation layer.

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