Superheated steam system of cooking utensil

Abstract

The utility model relates to a superheated steam system of a cooking utensil, aiming at solving the technical problems that the heating area of a heating pipe in a superheated evaporator of the existing similar cooking utensil is smaller, the displayed temperature fluctuation is larger, the accurate real-time detection is more difficult, the water is easily sprayed all the time, and the false alarm is often caused. A main body of the system is an integrated overheating evaporator, and a heating pipe is coiled in a waist shape and is arranged in the pipe diameter direction of a spiral coiled pipe of an evaporation pipe; the device is characterized in that two terminals at a heating pipe of the integrated overheating evaporator simultaneously extend out of an aluminum alloy shell at one end of a steam port of an evaporation pipe, the aluminum alloy shell is provided with a temperature controller, and an NTC temperature sensor is arranged at one end of a water inlet of the evaporation pipe; a steam spraying pipe is arranged at one end, extending into a groove in a metal heat insulation layer above a pot opening of a pot body in the machine body, of the steam pipe; the steam spraying pipe is bent in an S shape and is arranged on the outer side of a heating pipe above the pot opening of the pot body; temperature monitoring of the heating pipe is divided into five stages to control on-off and periods of the water pump and the heating pipe.

Description

Technical Field

[0001] The utility model relates to an overheat steam system of a steam cooking appliance, and is an overheat steam system of a cooking appliance. Background Technique

[0002] An air fryer is a new type of household appliance that uses high-speed air circulation technology to fry food. The food made by it can reduce 80% of the grease compared with a traditional electric fryer. It is easy to clean in daily use, safe and economical, and is favored by people. Some existing air fryers are combined with a steam function and are called steam air fryers. They are household appliances that combine the functions of an air fryer and a steam oven. They have both the functions of an air fryer and a steam oven. However, their steam airtightness requirements are relatively high. The core technology is to add components such as a water tank, a water pump, a steam generator, and a nozzle on the basis of an air fryer. The above-mentioned steam generator is also simply called an evaporator. The main indicators of the steam generator include steam temperature, steam dryness, steam velocity, and product volume. Among them, in terms of steam temperature, the steam temperature generated by a common single-stage steam generator is ≤100°C. The steam temperature is low, the temperature difference with the same food ingredients is small, the heat transfer speed is relatively slow, the cooking time of the food ingredients is relatively long, the yield rate is relatively low, and the oxidation degree of the food ingredients is relatively high. In terms of steam dryness, the steam dryness of a common single-stage steam generator is ≤92%. The steam dryness is low, and the energy carried per unit weight is relatively small. In terms of steam velocity, the steam velocity of an overheat evaporator is relatively fast. However, an air fryer is different from a steam oven. The volume of an air fryer is relatively small, and the steam will directly hit the wall of the fryer, resulting in low efficiency. In terms of product volume, traditional overheat evaporators are two-stage, divided into two steam generators. One stage generates saturated steam, and the second stage generates overheat steam. Such a combination method makes the volume of the steam generator relatively large, resulting in poor versatility and high cost.

[0003] Meanwhile, similar steam generators on the market are mainly divided into two categories by type: flow-channel steam generators and water-boiling steam generators. Among them, flow-channel steam generators have the characteristics of low cost, small size, and strong versatility. However, because the water-loading space is relatively small, they are very prone to water spraying and triggering water shortage alarms. Since the water level in the steam generator is mainly detected by temperature, it is extremely difficult to control. None of the current products on the market can solve the problem of water spraying. Water-boiling steam generators are equipped with NTC and water level probes, which can accurately detect whether there is water in the steam generator. In addition, they have a relatively large water-loading space and generally have an internal water-vapor separation structure, making them an ideal type of steam generator. However, this type of steam generator is relatively large in size and has poor versatility. Existing such steam generators or superheated evaporators include, for example, the steam generator with variable power heating tubes disclosed in Chinese Patent Document with application number 201921475917.1, authorization announcement date 2020.06.19, and utility model name "Steam Generator Based on Variable Power Heating Tubes"; and another example is the steam generator disclosed in Chinese Patent Document with application number 201420328653.8, authorization announcement date 2014.10.22, and utility model name "Steam Generator". The heating tubes in the evaporation tubes of the above products and similar products lack a coiling structure design, and there is no temperature sensor design at the water inlet of the evaporation tube. As a result, the displayed temperature fluctuates greatly, and it is difficult to accurately control the working time and cycle of the heating tubes in the evaporation tube and the water pump through the program, leading to continuous water spraying and frequent false alarms of the products. Summary of the Invention

[0004] To overcome the above deficiencies, the purpose of the present utility model is to provide a superheated steam system for cooking appliances to solve the technical problems of the heating area of the heating tubes in the superheated evaporator of existing similar cooking appliances being relatively small, the displayed temperature fluctuating greatly, being difficult to accurately detect in real time, being prone to continuous water spraying, and frequent false alarms. The purpose is achieved through the following technical solutions.

[0005] A superheated steam system for a cooking appliance. The main body of the system is an integrated superheated evaporator. Inside the aluminum alloy shell of the integrated superheated evaporator, there is a spirally coiled evaporation tube. The water inlet and steam outlet of the evaporation tube extend out from both ends of the aluminum alloy shell respectively. The water inlet end of the evaporation tube is the saturated steam area, and the steam outlet end of the evaporation tube is the superheated steam area. The heating tube is arranged in a kidney-shaped coil along the diameter direction of the spiral coil of the evaporation tube. The water inlet and steam outlet of the evaporation tube are respectively connected to a water inlet pipe and a steam pipe. The key point of its structural design is that two terminal ends at the heating tube of the integrated superheated evaporator simultaneously extend out from the aluminum alloy shell at the steam outlet end of the evaporation tube. At least one temperature controller is provided on the outer diameter of the aluminum alloy shell on one side between the water inlet and steam outlet of the evaporation tube. An NTC temperature sensor is provided on the aluminum alloy shell at the water inlet end of the evaporation tube. The kidney-shaped coil shape of the heating tube of the above-mentioned integrated superheated evaporator increases the heating energy efficiency inside the evaporation tube and provides energy for water evaporation. The evaporation tube turns the water inside the tube into saturated steam and then into superheated steam. At the same time, the saturated steam area of the evaporation tube turns water into saturated steam at 100°C, and the superheated steam area of the evaporation tube turns the saturated steam at 100°C into superheated steam at 300°C. The NTC temperature sensor is close to the water inlet of the evaporation tube and one end of the heating tube in the saturated steam area on the water inlet side of the evaporation tube. Thus, the NTC temperature sensor being close to this end of the heating tube facilitates the NTC to quickly heat up and trigger a water shortage alarm when there is a water shortage. The NTC temperature sensor is close to the water inlet end of the evaporation tube. When water enters, the NTC can quickly cool down, enabling the main control to monitor whether the integrated superheated evaporator is working properly. The energy density at one end of the heating tube close to the saturated steam area of the evaporation tube is higher than that at the other end, and the energy density for water to turn into steam is relatively large.

[0006] The aluminum alloy shell of the integrated superheated evaporator is in the shape of a rectangular prism. Symmetrical arc chamfered circumferences are respectively provided on the two narrow sides, and raised mounting ears are respectively provided. On the top plane between the two narrow sides, mounting posts for the temperature controller are symmetrically raised. A raised mounting part is provided on one side of the NTC temperature sensor. The above is a specific structural embodiment of the aluminum alloy shell of the integrated superheated evaporator.

[0007] One end of the steam pipe extending into the groove at the metal heat insulation layer above the mouth of the inner pot body of the cooking appliance is provided with a steam spraying pipe. The steam spraying pipe is arranged in an S-shaped bend on the outside of the heating pipe above the mouth of the pot body. The above steam pipe and steam spraying pipe can also be integrally formed and installed for use.

[0008] A centrifugal fan is provided in the groove of the metal heat insulation layer above the heating tube. The centrifugal fan is connected to the motor shaft of the shaded-pole motor extending into the inner cover of the metal heat insulation layer. The shaded-pole motor is arranged in the motor slot of the plastic heat insulation layer in the head at the top of the metal heat insulation layer. The water inlet pipe is sequentially connected to the water outlet of the water tank through a water pump, a connecting pipe, and a water tank valve body assembly. The connection terminals of the shaded-pole motor, the heating tube, the water pump, and the heating tube of the integrated overheat evaporator are connected to the PCB control assembly through wires. The pot body is placed into the opening on one side of the machine body below the metal heat insulation layer. In the specific application embodiment of the above integrated overheat evaporator and its steam injection pipe in the steam fryer, the shape of the steam injection pipe mainly controls the steam flow direction and gives the steam a rotational force, so that the steam makes a rotational movement in the steam fryer, avoiding the steam directly spraying onto the steam fryer and resulting in low steam utilization rate.

[0009] Another NTC temperature sensor is provided on one side in the groove of the metal heat insulation layer. Thus, the speed of the centrifugal fan and the temperature of the heating tube are further adjusted according to the temperature change in the cavity.

[0010] The structure of the present utility model is reasonably designed, convenient for installation and use, with good temperature control and temperature sensing effects, and a wide application range. In particular, the installation position of the NTC temperature sensor is reasonable, and the control methods of the heating tube of the overheat evaporator and the water pump make the water spraying stable and reduce the false alarm rate of water shortage. It is suitable for use as the overheat steam system of cooking appliances such as steam fryers and the structural improvement of similar products. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of the internal structure of the embodiment of the present utility model. The dotted lines in the figure are the structures of the internal evaporation tube and heating tube.

[0012] Figure 2 is Figure 1 a schematic diagram of the internal structure of the internal evaporation tube. The dotted lines in the figure are the internal heating tubes.

[0013] Figure 3 is Figure 2 a side view structural diagram of the heating tube. The framed part in the figure is the saturated steam area where the energy density at one end of the heating tube is relatively high and close to the evaporation tube, and the energy density for water to turn into steam is relatively large.

[0014] Figure 4 is the temperature control logic block diagram of the present utility model.

[0015] Figure 5 is the curve graph of the pressure and flow rate changes in the ideal gas formula.

[0016] Figure 6 is the curve graph of the comparison of steam data before and after the improvement of the present utility model.

[0017] Figure 7It is a curve graph showing the comparison and change of steam data after the improvement of the present utility model.

[0018] Figure 8 It is a schematic top view of the using state of the present utility model in a large and small double-pot steam fryer. The outer cover of the machine head, the inner cover of the machine head and the water tank are omitted in the figure. The solid arrow in the figure indicates the water inlet direction, and the hollow arrow indicates the steam direction. Part A in the figure is framed.

[0019] Figure 9 It is Figure 8 An enlarged view of Part A.

[0020] Figure 10 It is Figure 8 A schematic internal structure view of the state when the large and small pot bodies are taken out. Part B in the figure is framed.

[0021] Figure 11 It is Figure 10 An enlarged view of Part B.

[0022] Reference numerals and names of the drawings: 1. Integrated superheated evaporator, 101. Aluminum alloy shell, 102. Evaporation tube, 1021. Saturated steam area, 1022. Superheated steam area, 103. Heating tube, 2. Water pump, 3. Water inlet pipe, 4. NTC temperature sensor, 5. Thermostat, 6. Steam pipe, 7. Shaded-pole motor, 8. Plastic heat insulation layer, 9. Connecting pipe, 10. Steam injection pipe, 11. Metal heat insulation layer, 12. Heating element, 13. Centrifugal fan. Detailed implementation manners

[0023] Now, in combination with the drawings, the structure and use of the present utility model will be further described. As Figures 1 - 11As shown in the figure, the main body of the system is an integrated superheated evaporator 1. Inside the aluminum alloy shell 101 of the integrated superheated evaporator, there is a spirally coiled evaporation tube 102. The water inlet and steam outlet of the evaporation tube extend out of both ends of the aluminum alloy shell respectively. One end of the water inlet of the evaporation tube is the saturated steam area 1021, and one end of the steam outlet of the evaporation tube is the superheated steam area 1022. The heating tube 103 is coiled in a waist shape and arranged inside along the diameter direction of the spiral coiling of the evaporation tube. The water inlet and steam outlet of the evaporation tube are connected to the water inlet pipe 3 and the steam pipe 6 respectively. At the steam outlet end of the aluminum alloy shell of the evaporation tube, two wiring terminals at the heating tube of the above integrated superheated evaporator extend out simultaneously. On the outer diameter of the aluminum alloy shell on one side between the water inlet and steam outlet of the evaporation tube, there is at least one temperature controller 5. At one end of the aluminum alloy shell at the water inlet of the evaporation tube, there is an NTC temperature sensor 4. The aluminum alloy shell of the integrated superheated evaporator is in the shape of a rectangular column. On both narrow sides, there are symmetric arc chamfered circumferential surfaces respectively, and there are protruding mounting ears respectively. On the top plane between the two narrow sides, there are symmetrically protruding mounting posts for the temperature controller. On one side of the NTC temperature sensor, there is a protruding mounting part. One end of the steam pipe extends into a groove at the metal heat insulation layer 11 above the pot mouth of the inner pot body of the machine body and is provided with a steam spraying pipe 10. The steam spraying pipe is arranged in an S-shaped bend outside the heating pipe 12 above the pot mouth of the pot body. Inside the groove of the metal heat insulation layer above the heating pipe, there is a centrifugal fan blade 13. The centrifugal fan blade is connected to the motor shaft of the shaded pole motor 7 extending into the metal heat insulation layer. The shaded pole motor is arranged in the motor slot of the plastic heat insulation layer 8 at the top of the metal heat insulation layer. The water inlet pipe is sequentially connected to the water outlet of the water tank through the water pump 2, the connecting pipe 9, and the water tank valve body assembly. The wiring terminals at the shaded pole motor, the heating pipe, the water pump, and the heating pipe of the integrated superheated evaporator are connected to the PCB control assembly through wires. The pot body is placed into the machine body through an opening on one side below the metal heat insulation layer. On one side inside the groove of the metal heat insulation layer, there is another NTC temperature sensor.

[0024] This system solves the problem of water spraying by optimizing the structure of the existing flow-through steam generator and the temperature control algorithm. The product structure, temperature control logic and algorithm, and the comparison of steam data before and after are as follows:

[0025] I. Product structure

[0026] This product mainly consists of an integrated overheat evaporator, a water pump, a shaded pole motor, a stirring fan blade, a heating tube, a housing, and an NTC temperature sensor; among them, the integrated overheat evaporator turns water into superheated steam at 100°C; the water pump pumps the water in the water tank into the integrated overheat evaporator; the shaded pole motor provides power for the stirring fan blade; the centrifugal fan blade makes the steam evenly distributed in the cavity; the energy of the heating tube is mainly introduced into the cavity in the form of forced convection. In addition, the water in the evaporation tube of the integrated overheat evaporator turns into saturated steam in the evaporation tube and then into superheated steam; the heating tube provides energy for water evaporation; the saturated steam area at one end of the evaporation tube turns water into saturated steam at 100°C; the superheated steam area at the other end turns the saturated steam at 100°C into superheated steam at 300°C; the energy density of the heating tube near the saturated steam area of the evaporation tube is relatively high and should be close to the yellow part of the evaporation tube, and the energy density of water turning into steam is relatively large. The NTC temperature sensor of the above aluminum alloy housing should be installed close to the heating tube and the water inlet. When the NTC is close to the heating tube, it can quickly heat up and trigger a water shortage alarm when there is a water shortage; when the NTC temperature sensor is close to the water inlet, it can quickly cool down when water is entering, so that the main control can monitor whether the integrated overheat evaporator is working properly.

[0027] As Figure 10 , Figure 11 shown, the shape of the steam spray pipe on one side in the metal heat insulation layer groove mainly controls the steam flow direction and gives the steam a rotational force, so that the steam makes a rotational movement in the steam fryer, avoiding the steam directly spraying onto the steam fryer and resulting in low steam utilization rate. At the same time, during the working process of the steam fryer in the steaming mode, the centrifugal fan blade rotates at a speed of 700 RPM, applying a rotational force to the steam again to make the steam evenly cover the entire cavity.

[0028] II. Temperature Control Logic and Algorithm

[0029] 1. The NTC temperature sensor starts monitoring 1 second after water inlet, and the heating tube of the integrated overheat evaporator conducts temperature control according to the following formula;

[0030]

[0031] In the formula, k is the sampling sequence number, k = 0, 1, 2,...; u k is the computer output value at the kth sampling moment; e k is the deviation value input at the kth sampling moment; e (k-1) is the deviation value input at the (k - 1)th sampling moment; Ki is the integral coefficient, Ki = Kp × T / Ti; Kd is the differential coefficient, Kd = Kp × Td / T; the duty cycle of the heating tube is automatically calculated through the above formula to keep the NTC temperature between 115°C and 125°C.

[0032] Thus, the above-mentioned stable temperature makes the internal pressure of the integrated superheated evaporator relatively stable, and the water inflow will also be stable and controllable; because the pressure has a great influence on the water inflow of the water pump, as Figure 5 shown:

[0033] PV = nRT, the above ideal gas formula, where P represents pressure, V represents volume, T represents temperature, n represents the amount of substance, and R is a constant; according to the ideal gas formula, it can be known that temperature and pressure are proportional, and when the temperature is stable, the pressure in the pipeline will also be stable, thus effectively solving the problem of water spraying.

[0034] 2. Duty cycle of the heating tube:

[0035] 30 / 30: The heating tube is on for 30S and off for 0S, with a cycle of 30S;

[0036] 27 / 30: The heating tube is on for 27S and off for 3S, with a cycle of 30S;

[0037] 10 / 30: The heating tube is on for 10S and off for 20S, with a cycle of 30S;

[0038] 0 / 30: The heating tube is on for 0S and off for 30S, with a cycle of 30S.

[0039] 3. Duty cycle of the water pump:

[0040] 0.14 / 1: The water pump is on for 0.14S and off for 0.86S, with a cycle of 1S;

[0041] 0.2 / 1: The water pump is on for 0.2S and off for 0.8S, with a cycle of 1S.

[0042] A smaller cycle can effectively control the temperature of the water pump coil and make the water intake of the water pump stable; the temperature of the water pump coil will affect the energy efficiency of the water pump, and the higher the temperature, the lower the energy efficiency.

[0043] 4. When NTC ≤ 50°C,

[0044] 5. When 50°C < NTC ≤ 115°C,

[0045] 6. When 115°C < NTC < 125°C, the heating tube is not fully powered on to prevent the temperature of the integrated superheated evaporator from being too high and triggering the sudden jump temperature control protection.

[0046] 7. When 125°C < NTC < 150°C, it belongs to the over-temperature stage; the duty cycle of the heating tube is 10 / 30, mainly to make the integrated superheated evaporator cool down slowly, stably generate steam, and increase the water inflow to reduce the temperature of the integrated superheated evaporator.

[0047] 8. When NTC ≥ 150°C, it belongs to the water shortage state, and the heating tube should be immediately turned off.

[0048] III. Comparison of Steam Data before and after

[0049] 1. Before improvement: As Figure 6 shown, the NTC temperature display of the evaporator fluctuates greatly, resulting in continuous water spraying of the product and frequent false alarms.

[0050] 2. After improvement: As Figure 7 shown, the NTC temperature of the evaporator is very stable, thus solving the problems of water spraying and false alarms of water shortage.

[0051] The above is intended to illustrate the technical means of the present utility model and does not limit the technical scope of the present utility model. Obvious improvements or replacements made by those skilled in the art in combination with the existing common general knowledge also fall within the protection scope of the claims of the present utility model. For example: According to the existing technology, another thermostat is provided at the thermostat of the integrated overheat evaporator, and a cross-flow fan is provided in the cavity between the plastic heat insulation layer and the metal heat insulation layer of the steam fryer. A steam fryer with a separate steam function, or a double-chamber steam fryer with the same size or a double-chamber steam fryer with different sizes, with a steam function on one side and an air fry function on the other side.

Claims

1. An overheated steam system for a cooking appliance. The main body of the system is an integrated overheat evaporator (1). Inside the aluminum alloy housing (101) of the integrated overheat evaporator, there is a spirally coiled evaporation tube (102). The water inlet and steam outlet of the evaporation tube extend out from both ends of the aluminum alloy housing respectively. One end of the water inlet of the evaporation tube is a saturated steam area (1021), and one end of the steam outlet of the evaporation tube is an overheated steam area (1022). The heating tube (103) is arranged in a kidney-shaped coil along the diameter direction of the spiral coil of the evaporation tube. The water inlet and steam outlet of the evaporation tube are respectively connected to a water inlet pipe (3) and a steam pipe (6); characterized in that At two terminal ends of the heating pipe (103) of the integrated superheated evaporator (1), they simultaneously extend out of the aluminum alloy shell (101) at one end of the steam port of the evaporation pipe (102). At least one temperature controller (5) is provided on the outer diameter of the aluminum alloy shell on one side between the water inlet and the steam port of the evaporation pipe. An NTC temperature sensor (4) is provided on the aluminum alloy shell at one end of the water inlet of the evaporation pipe.

2. The overheat steam system of the cooking appliance according to claim 1, wherein The aluminum alloy shell (101) of the integrated superheated evaporator (1) is in the shape of a rectangular column. Symmetric arc chamfered circumferences are respectively provided on the two narrow sides, and protruding mounting ears are respectively provided. Mounting posts for the temperature controller (5) are symmetrically protruding on the top plane between the two narrow sides. A protruding mounting portion is provided on one side of the NTC temperature sensor (4).

3. The overheated steam system of the cooking appliance according to claim 1, characterized in that One end of the steam pipe (6) extending into the groove at the metal heat insulation layer (11) above the pot mouth of the inner pot body of the machine body is provided with a steam spray pipe (10). The steam spray pipe is arranged in an S shape and is located outside the heating pipe (12) above the pot mouth of the pot body.

4. The overheat steam system of the cooking appliance according to claim 3, wherein A centrifugal fan blade (13) is provided in the groove of the metal heat insulation layer (11) above the heating pipe (12). The centrifugal fan blade is connected to the motor shaft of the shaded pole motor (7) extending into the metal heat insulation layer. The shaded pole motor is arranged in the motor groove of the plastic heat insulation layer (8) at the top of the metal heat insulation layer. The water inlet pipe is sequentially connected to the water outlet of the water tank through the water pump (2), the connecting pipe (9), and the water tank valve body assembly. The terminal ends at the shaded pole motor, the heating pipe, the water pump, and the heating pipe (103) of the integrated superheated evaporator (1) are connected to the PCB control assembly through wires. The pot body is placed into the machine body through an opening on one side below the metal heat insulation layer.

5. The overheat steam system of the cooking appliance according to claim 4, characterized in that Another NTC temperature sensor (4) is provided on one side in the groove of the metal heat insulation layer (11).

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