An oven and temperature control method for making chiffon cakes without preheating

Abstract

This invention relates to an oven and temperature control method for making chiffon cakes without preheating. It addresses the technical problem of existing similar products having relatively simple temperature monitoring methods, making it difficult to perfectly produce chiffon cakes. The oven has an inner convection plate on the inner diameter of one side of its metal lining opening, and an NTC temperature sensor extending into the lining to sense the temperature at the center of the cavity. The key feature is that the inner convection plate, corresponding to the groove in the lining plate, has a rectangular air inlet groove protruding into the oven cavity. The rectangular plane of the air inlet groove has an air inlet area with equidistantly distributed ventilation holes. The inclined sides of the air inlet groove on the inner convection plate, aligned with the upper and lower heating elements, have equidistantly distributed air outlet areas. An infrared sensor is installed in the metal lining above the upper heating element on one side of the inner convection plate inside the oven cavity. The infrared sensor, combined with the NTC temperature sensor, controls the temperature at the center point of the cavity.

Description

Technical Field

[0001] This invention relates to ovens, specifically an oven and temperature control method for making chiffon cakes preheat-free. Background Technology

[0002] An oven is a sealed appliance used for baking food or drying products. Ovens are categorized into household and industrial ovens. Household ovens typically use radiant heat from heating elements to bake food, such as roast chicken, roast duck, and bread. Depending on the type of food being baked, the temperature of an electric oven is generally adjustable within the range of 50-250℃. Some ovens currently use NTC temperature sensors to control the temperature inside the oven, such as Chinese patent application number 202221068093.8, authorized on December 16, 2022, entitled "An NTC Temperature Sensor for Ovens and an Oven Using It"; and another example is Chinese patent application number 202010325582.6, published on October 26, 2021, entitled "A Method for Baking Cakes in an Oven." However, these products and similar items are difficult to precisely apply to the cooking and processing of chiffon cakes. The changes in a chiffon cake inside the oven mainly consist of three stages: expansion, setting, and browning. Traditional ovens cause this primarily because: 1. The heating elements in traditional ovens reach high temperatures during the heating process, resulting in high radiation intensity inside the oven. Using the frequency formula λ=v / f, it's known that the radiation energy frequency of metal heating elements is relatively low. The lower the frequency, the lower the penetration depth of the radiation energy. This causes a large amount of radiation energy to accumulate on the surface of the chiffon cake, resulting in a cake that is burnt on the outside but raw on the inside, and with a relatively low expansion height. 2. Traditional ovens generally have lower thermal efficiency, leading to a slower heating rate and causing the heating elements to remain at high temperatures for extended periods. Summary of the Invention

[0003] To overcome the above shortcomings, the purpose of this invention is to provide an oven and temperature control method for making chiffon cakes without preheating, thereby solving the technical problems of large temperature fluctuations at the center point of the cavity in existing similar products, difficulty in accurately controlling the cavity temperature, and the relatively simple temperature monitoring methods during the cooking process, which make it difficult to achieve perfect chiffon cake making. This objective is achieved through the following technical solution.

[0004] An oven for making chiffon cakes without preheating is disclosed. The oven has a door on one side of its body, a metal liner inside, and a door on one side of the metal liner. An inner convection plate is installed on the inner diameter of the other side of the metal liner. A centrifugal impeller and a back heating element are installed in a groove in the inner liner at the bottom of the inner convection plate. A rear cover is installed at the bottom of the inner liner. An upper heating element and a lower heating element are installed in the cavity formed by the connection between the rear cover and the metal liner. A shaded pole motor is installed at the bottom of the rear cover. The drive shaft of the shaded pole motor is connected to the centrifugal impeller through the rear cover and the inner liner. An NTC temperature sensor is installed on one side of the metal liner to sense the temperature at the center of the cavity. The NTC temperature sensor, the upper heating element, the lower heating element, the back heating element, and the shaded pole motor are connected to a power board inside the oven via wiring. The key structural design features an inner convection plate with a rectangular air inlet groove protruding into the housing, corresponding to the groove in the inner liner. The groove openings of the inner convection plate and the groove openings of the inner liner are aligned to form a recessed cavity for the centrifugal impeller and the back heating pipe. The inner convection plate has an air inlet area with equidistantly distributed ventilation holes in the middle of the rectangular plane of the air inlet groove. The inner convection plate with the upper and lower heating pipes aligned has an air outlet area with equidistantly distributed ventilation holes on the inclined side of the air inlet groove. An infrared sensor is installed in the metal liner above the upper heating pipe on one side of the inner convection plate inside the housing. The infrared sensor is connected to the power board inside the housing via wiring. The temperatures of the upper and lower heating pipes are set to be the same or different through a control program. The above structural design combines an infrared sensor with an NTC temperature sensor. The NTC temperature sensor maps the temperature at the center point of the cavity, thereby controlling the temperature at the center point of the cavity. The main function of the inner convection plate is to increase the airflow speed and control the airflow direction. The main function of the infrared sensor is to provide feedback on the temperature of the upper heating element at the air inlet area of ​​the inner convection plate. While controlling the temperature of the upper and lower heating elements, it also prevents the radiation intensity of the upper and lower heating elements from being too high, and avoids excessive radiation energy caused by excessive temperature, thus preventing the surface of the chiffon cake from absorbing too much radiation energy and browning prematurely.

[0005] The air outlet area of ​​the inner convection plate is provided with heating pipe side grooves on both sides. The corresponding square mounting plates at the wiring ends of the upper and lower heating pipes are set on the inner lining plate through the heating pipe side grooves of the inner convection plate.

[0006] The induction area at the end of the NTC temperature sensor is between 40 - 60 mm away from the upper heating tube. Thus, the temperature at the center point of the cavity is mapped through the temperature of the NTC temperature sensor to control the temperature at the center point of the cavity. The position of the NTC temperature sensor cannot be too close to the upper heating tube. Before the central temperature of the cavity rises, the temperature of the NTC temperature sensor is already very high, resulting in the central temperature of the cavity not reaching the set temperature. The position of the NTC temperature sensor cannot be too far from the upper heating tube. When the central temperature of the cavity is already very high, the temperature of the NTC temperature sensor is very low, resulting in a very high central temperature of the cavity. The temperature control effect is optimal when the NTC temperature sensor is between 40 - 60 mm away from the upper heating tube.

[0007] The back heating tube is circular. The wiring terminal of the back heating tube is arranged on one side of the center of the rear lining cover. The centrifugal impeller is arranged in the middle of the back heating tube. The shaded-pole motor is arranged in the circular groove in the middle of the rectangular bottom of the rear lining cover.

[0008] The centrifugal impeller is aligned with the air inlet area in the middle of the rectangular plane on the inner convection plate, and the back heating tube is aligned with the outer rectangular plane of the air inlet area on the inner convection plate. The above structure blocks the radiant energy of the back heating tube by the inner convection plate, and the temperature of the back heating tube does not need to be controlled.

[0009] At the rear of the outer shell of the machine body, there is a rear convection plate serving as the rear cover plate. In the center of the rectangular trumpet-shaped middle platform that protrudes backward from the rear convection plate, there is a circular platform that continues to protrude backward. The shaded-pole motor corresponds to the groove at the circular platform on the inner side of the rear convection plate. The middle platform and the circular platform of the rear convection plate are respectively provided with heat dissipation holes, and a wiring hole is provided on the middle platform on one side of the heat dissipation holes.

[0010] This temperature control method controls the temperature curve suitable for the cake during the production process of chiffon cake through a program. The specific steps are as follows: The surface temperature T of the chiffon cake: When T < T1, it means the cake enters the expansion stage; when T1 ≤ T < T2, it means the cake enters the setting stage; when T ≥ T2, it means the cake enters the browning stage. First, the infrared sensor senses the surface temperature of the chiffon cake to determine which stage the chiffon cake is in, and then calls the corresponding control program.

[0011] The NTC temperature sensor detects the temperature at the center point of the cavity every 1 s, and the infrared sensor detects the temperature of the heating tube and the cake every 1 s. When T = T3, the cooking ends and reminds the user to take it out. When the infrared sensor detects that the temperature of the upper heating tube exceeds 300 °C, the power of the upper and lower heating tubes is reduced by 10%. After the temperature of the upper and lower heating tubes returns to the limit, the following duty cycle is executed according to the command, and the upper and lower heating tubes control the first priority. When the infrared sensor detects that T < T1, it is detected by the NTC temperature sensor in the expansion stage; T

[0010] < T 〃When it is 1, the shaded-pole motor, the upper heating tube, the lower heating tube, and the back heating tube are respectively in a 100% working state; T 〃 1 ≤ T 〃 ≤ T 〃 When it is 2, the shaded-pole motor is in a 100% working state, the upper heating tube is in a 24% working state, the lower heating tube is in an 18% working state, and the back heating tube is in a closed state; when the infrared sensor detects that T1 ≤ T < T2, the cake enters the shaping stage, the shaded-pole motor is in a 100% working state, the upper heating tube is in a 28% working state, the lower heating tube is in a 20% working state, and the back heating tube is in a closed state; when the infrared sensor detects that T ≥ T2, the cake enters the browning stage, the shaded-pole motor is in a 100% working state, the upper heating tube is in a 35% working state, the lower heating tube is in a 30% working state, and the back heating tube is in a closed state; the above T 〃 is the central temperature of the cavity; T3 is the maturity temperature of the cake. This temperature control method controls the temperature of the upper heating tube to avoid too high radiation intensity of the upper heating tube; the expansion process requires a long time to evenly gelatinize the flour and let the air slowly expand to avoid depression and collapse, so it does not require a large amount of energy; the energy needs to be increased during the shaping stage to quickly form a crust on the surface; the browning stage requires a short time and high energy, and the short time locks in the internal moisture to avoid cracking of the chiffon cake.

[0012] The structure of the present invention is reasonably designed, the cavity temperature and the central point temperature of the cavity are precisely controlled, the fluctuation of the central point temperature of the cavity is small, and the proportion of radiation energy is low; it is suitable for use as an oven for realizing chiffon cake without preheating and its temperature control method, as well as the structural improvement of similar products. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the internal structure of the embodiment box of the present invention, and the outer shell and the rear convection plate of the box are omitted in the figure.

[0014] Figure 2 is Figure 1 a partial cross-sectional structural schematic diagram, the dotted line in the figure is the outer shell and the rear convection plate of the box, and the arrow is the air direction.

[0015] Figure 3 is Figure 1 a structural schematic diagram of the state where the internal convection plate is taken out.

[0016] Figure 4 is a schematic diagram of the control logic block flow of the present invention.

[0017] Attached figures and their names: 1. Inner convection plate; 101. Air inlet area; 102. Air outlet area; 103. Heating tube side groove; 2. NTC temperature sensor; 3. Inner liner; 4. Rear liner; 5. Infrared sensor; 6. Shaded pole motor; 7. Centrifugal impeller; 8. Back heating tube; 9. Upper heating tube; 10. Lower heating tube; 11. Rear convection plate. Implementation

[0018] The structure and use of the present invention will now be further described with reference to the accompanying drawings. Figures 1-3 As shown, the oven has a door on one side of its body, a metal liner inside, a door on one side of the metal liner, and an inner convection plate 1 on the inner diameter of the other side of the metal liner. A centrifugal impeller 7 and a back heating tube 8 are located in the groove of the inner liner plate 3 at the bottom of the inner convection plate. A rear cover 4 is located at the bottom of the inner liner plate. An upper heating tube 9 and a lower heating tube 10 are respectively located in the cavity formed by the connection between the rear cover and the metal liner. A shaded pole motor 6 is located at the bottom of the rear cover. The drive shaft of the shaded pole motor is connected to the centrifugal impeller through the rear cover and the inner liner plate. An NTC temperature sensor 2 is located on one side of the metal liner and is used to sense the temperature of the center of the cavity. The NTC temperature sensor, the upper heating tube, the lower heating tube, the back heating tube, and the shaded pole motor are connected to the power board inside the oven through wiring. The inner convection plate corresponding to the groove of the inner lining plate has a rectangular air inlet slot protruding into the box. The slot openings of the inner convection plate and the groove openings of the inner lining plate are aligned to form a recessed cavity for the centrifugal impeller and the back heating pipe. The air inlet area 101 with equidistantly distributed circular ventilation holes is provided in the middle of the rectangular plane of the air inlet slot of the inner convection plate. The inclined side of the air inlet slot of the inner convection plate, which is aligned with the upper and lower heating pipes, has waist-shaped ventilation holes with equidistantly distributed air outlet areas 102. An infrared sensor 5 is installed in the metal lining of the upper heating pipe on one side above the inner convection plate inside the box. The infrared sensor is connected to the power board inside the box through a circuit. The temperatures of the upper and lower heating pipes are set to the same temperature through a control program. Heating pipe side slots 103 are symmetrically provided on both sides of the air outlet area of ​​the inner convection plate. The square mounting plates corresponding to the wiring terminals of the upper and lower heating pipes are set on the inner lining plate through the heating pipe side slots of the inner convection plate.

[0019] The induction area at the end of the above NTC temperature sensor is between 40 - 60 mm from the upper heating tube. The back heating tube is circular, and the wiring terminal of the back heating tube is set on one side of the center of the rear lining cover. The centrifugal impeller is set in the middle of the back heating tube, and the shaded-pole motor is set in the circular groove in the middle of the rectangular bottom of the rear lining cover. At the same time, the centrifugal impeller is aligned with the air inlet area in the middle of the rectangular plane on the inner convection plate, and the back heating tube is aligned with the rectangular plane outside the air inlet area on the inner convection plate. At the rear of the outer shell of the machine body, there is a rear convection plate 11 serving as the rear cover plate. In the center of the rectangular trumpet-shaped middle platform that protrudes backward on the rear convection plate, there is a circular platform that continues to protrude backward. The shaded-pole motor corresponds to the groove at the circular platform on the inner side of the rear convection plate. The middle platform and the circular platform of the rear convection plate are respectively provided with heat dissipation holes, and a wiring hole is provided on the middle platform on one side of the heat dissipation holes.

[0020] As Figure 2 shown, the arrows in the figure indicate the flow of air in the cavity. The upper and lower openings of the inner convection plate allow a large amount of relatively cold air to flow through the upper and lower heating tubes, and take away the heat of the upper and lower heating tubes, thereby effectively controlling the temperature of the upper and lower heating tubes and improving the energy utilization rate of the upper and lower heating tubes.

[0021] As Figure 4 shown, the above NTC temperature sensor detects the temperature at the center point of the cavity every 1 s, and the infrared sensor detects the temperature of the heating tube and the cake every 1 s. When T = T3, the cooking ends and it reminds the user to take out; when the infrared sensor detects that the temperature of the lower heating tube exceeds 300 °C, the power of the heating tube is reduced by 10%. After the temperature of the heating tube is restored to the limit, the following duty ratio is executed according to the command, and the heating tube control has the first priority; when the infrared sensor detects that T < T1, it is detected by the NTC temperature sensor in the expansion stage; T 〃 < T 〃 1, the shaded-pole motor, the upper heating tube, the lower heating tube, and the back heating tube are respectively in a 100% working state; T 〃 1 ≤ T 〃 ≤ T 〃 2, the shaded-pole motor is in a 100% working state, the upper heating tube is in a 24% working state, the lower heating tube is in an 18% working state, and the back heating tube is in a closed state; when the infrared sensor detects that T1 ≤ T < T2, the cake enters the shaping stage, the shaded-pole motor is in a 100% working state, the upper heating tube is in a 28% working state, the lower heating tube is in a 20% working state, and the back heating tube is in a closed state; when the infrared sensor detects that T ≥ T2, the cake enters the browning stage, the shaded-pole motor is in a 100% working state, the upper heating tube is in a 35% working state, the lower heating tube is in a 30% working state, and the back heating tube is in a closed state; the above T 〃T1 represents the temperature at the center of the cavity; T3 represents the cake's baking temperature. During the above process, the temperatures of the upper and lower heating elements are set to the same temperature through the control program. The temperature of the lower or upper heating element can be roughly inferred from the corresponding temperature of the upper or lower heating element, and the duty cycle of both is the same.

[0022] In summary, this oven includes a shaded-pole motor, a centrifugal impeller, an internal convection plate, an annular back heating element, an upper heating element, a lower heating element, an NTC temperature sensor, an infrared sensor, an outer shell, and a door. The entire system generates heat energy within the cavity through the back heating element, upper heating element, and lower heating element. The centrifugal impeller rotates and stirs the air within the cavity, carrying the energy generated by the upper and lower heating elements into the cavity. The energy generated by the upper and lower heating elements is primarily exchanged with the food through forced convection, and secondarily through thermal radiation. This oven eliminates the preheating problem in chiffon cake baking, shortening the preheating time and improving the efficiency of the upper and lower heating elements. It has the following advantages: 1. Improved overall machine efficiency during the preheating stage by increasing the motor speed of the shaded-pole motor to increase the forced convection coefficient; 2. Hot air from the internal convection plate blows onto the upper and lower heating elements, creating an upward and downward turbulent airflow that carries the energy from the upper and lower heating elements.

Claims

1. A kind of to realize chiffon cake preheating-free oven, the side opening of the oven body is equipped with oven door, the metal lining is equipped in the oven body, the side opening of the metal lining is equipped with the inner convection plate (1) in the inner diameter, the recess of the bottom lining plate (3) of the inner convection plate is equipped with centrifugal impeller (7) and back heating tube (8), the bottom of the lining plate is equipped with rear lining cover (4), the cavity formed by the connection of rear lining cover and metal lining is respectively equipped with upper heating tube (9) and lower heating tube (10), the bottom of the rear lining cover is equipped with shield motor (6), the transmission shaft of shield motor is connected with centrifugal impeller through rear lining cover, lining plate;The side of metal lining is equipped with NTC temperature sensor (2) for extending into and sensing the temperature of cavity center, NTC temperature sensor, upper heating tube, lower heating tube, back heating tube, shield motor are connected with power board in the oven body by line;Its characterized in that The recess of the inner lining plate (3) corresponds to the inner convection plate (1) provided with a rectangular air inlet groove protruding into the box. The slot at the air inlet and outlet grooves of the inner convection plate is aligned with the slot at the recess of the inner lining plate to form a recess cavity for setting the centrifugal impeller (7) and the back heating pipe (8). The air inlet area (101) of the air inlet groove of the inner convection plate is provided with air inlet holes equidistantly distributed in the middle of the rectangular plane. The air outlet area (102) of the air outlet groove of the inner convection plate is provided with air outlet holes equidistantly distributed on the inclined surface of the air inlet groove. The metal lining at the upper heating pipe on the top of the inner convection plate in the box is provided with an infrared sensor (5). The infrared sensor is connected to the power panel in the box through a line. The temperatures of the upper heating pipe and the lower heating pipe are set to the same or different temperatures through a control program. The air outlet area (102) of the inner convection plate (1) is provided with heating pipe side grooves (103) symmetrically arranged on both sides of the air outlet area (102). The connection end of the upper heating pipe (9) and the lower heating pipe (10) is provided with a square mounting plate corresponding to the heating pipe side groove of the inner convection plate on the inner lining plate (3). The sensing area of the end of the NTC temperature sensor (2) is 40-60mm away from the upper heating pipe (9). The temperature curve suitable for the cake during the making of the chiffon cake is controlled through the program. The specific steps are as follows: the surface temperature T of the chiffon cake: T 〃 < T 〃 1, the shaded pole motor (6), the upper heating pipe (9), the lower heating pipe and the back heating pipe (8) are respectively in a 100% working state; T 〃 1≤T 〃 ≤ T 〃 2, the shaded pole motor is in 100% working state, the upper heating tube is in 24% working state, the lower heating tube is in 18% working state, and the back heating tube is in closed state; when the infrared sensor detects T1≤T<T2, the cake enters the shaping stage, the shaded pole motor is in 100% working state, the upper heating tube is in 28% working state, the lower heating tube is in 20% working state, and the back heating tube is in closed state; when the infrared sensor detects T≥T2, the cake enters the browning stage, the shaded pole motor is in 100% working state, the upper heating tube is in 35% working state, the lower heating tube is in 30% working state, and the back heating tube is in closed state; the above T 〃 T is the cavity center temperature; T3 is the cake maturity temperature.

2. The pre-heat free oven for making chiffon cake according to claim 1, wherein The back heating tube (8) is circular, the wiring end of the back heating tube is arranged at one side of the center of the rear lining cover (4), the centrifugal impeller (7) is arranged in the middle of the back heating tube, and the shield motor (6) is arranged in the circular groove in the middle of the rectangular bottom of the rear lining cover.

3. The pre-heat free oven for making chiffon cake according to claim 1, wherein The centrifugal impeller (7) is aligned with the air inlet area (101) in the middle of the rectangular plane on the inner convection plate (1), and the back heating tube (8) is aligned with the rectangular plane outside the air inlet area (101) on the inner convection plate.

4. The pre-heat free oven for making chiffon cakes as claimed in claim 1, wherein The rear part of the shell of the machine body is provided with a rear convection plate (11) as a rear cover plate, the center of the rear convection plate is provided with a circular platform which is further protruded backward, the shield motor (6) is correspondingly arranged in the groove of the circular platform on the inner side of the rear convection plate, the middle platform and the circular platform of the rear convection plate are respectively provided with heat dissipation holes, and the middle platform on one side of the heat dissipation holes is provided with a wiring hole.

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