A humidity control system for a steam oven

Abstract

A humidity control system for a steam oven includes an air guide plate assembly mounted on the top of the inner cavity. A hot air chamber is formed on the outer side of the hot air blower baffle, containing a heating element and fan blades. An air inlet channel is located on the outer side of the hot air chamber, with its inlet connected to the outside air and its outlet connected to the inside of the hot air chamber. The air inlet channel has a first detection port for detecting the external air pressure, and the hot air chamber has a second detection port for detecting the pressure at the fan blade outlet area. A differential pressure sensor is mounted on the outside of the inner cavity, with its first pressure measuring port connected to the first detection port and its second pressure measuring port connected to the second detection port. This humidity control system significantly increases the airflow of the hot air blower through the combined action of the first and second air duct systems. The fan blades and air guide plate assembly within the hot air chamber form a dual-channel forced dehumidification system, greatly improving the dehumidification speed. Furthermore, the humidity of the inner cavity can be calculated in real time through the signal feedback from the differential pressure sensor, achieving precise humidity control.

Description

Technical Field

[0001] This invention relates to a cooking appliance, and more particularly to a humidity control system for a steam oven. Background Technology

[0002] Currently, most steam ovens on the market lack humidity control, leading to poor cooking of humidity-sensitive dishes. Furthermore, the natural venting of steam from the inner cavity is too slow and lacks control over the rate of steam release, resulting in some dishes having a soggy surface. Additionally, the hot airflow from the fan is insufficient, preventing dishes requiring high airflow, such as crispy chicken, from achieving a crispy skin. A crispy skin requires high airflow at high temperatures to quickly remove moisture from the food's surface. While some products offer qualitative humidity control (high, medium, and low), humidity significantly impacts baking results, making quantitative humidity measurement crucial. However, traditional humidity sensors cannot be used directly at high temperatures and have lower accuracy under such conditions. Existing household steam cooking appliances, such as steam ovens, steam microwave ovens, or steam cookers, typically continuously inject steam into the cooking cavity or heat it directly within the cavity during the steaming process. Maintaining humidity within the cooking cavity within a specific range is essential for ensuring the texture and flavor of the food; therefore, humidity monitoring within the steam cooking appliance is necessary. For example, the "Steamer, Oven and Microwave Oven Combination Machine" disclosed in application number 201911111601.9 (application publication number CN 112790595 A) has a hot air circulation system including a hot fan and an exhaust system including an exhaust fan. The hot fan has a small air volume, and the dehumidification and descaling are mainly achieved by the exhaust fan. The exhaust fan is installed on the top of the cavity, occupying a certain space inside the cavity. Moreover, the use of two fans not only makes the structure more complex, but also increases the cost.

[0003] Humidification in a steam oven refers to adding water vapor into the inner cavity, usually by heating water with a boiler or steam generator to produce steam that flows into the inner cavity. Dehumidification is usually achieved through natural dehumidification, which involves opening an exhaust vent on the inner cavity and connecting it to an exhaust duct via a connecting pipe to allow the moisture to escape naturally. This dehumidification process is relatively slow.

[0004] Humidity includes absolute humidity and relative humidity. Absolute humidity refers to the mass of water vapor contained in a unit volume of air, usually expressed in meters per cubic meter (m³). 3The relative humidity is expressed in grams of water vapor contained in the air. This is the density of water vapor. Water vapor pressure increases with increasing density, so the absolute humidity of the air can also be expressed through water vapor pressure. Relative humidity refers to the percentage of the actual water vapor density in the air to the saturated water vapor density at the same temperature; it can be expressed as the ratio of the absolute humidity of the air to the maximum absolute humidity reached at the same temperature, or as the ratio of water vapor pressure to saturated water vapor pressure. The degree of dryness or humidity of the air is related to the degree to which the air is close to saturation with water vapor, and not directly related to the absolute amount of water vapor in the air. For example, if the water vapor pressure in the air is the same (1606 Pa), people will not feel humid in summer because the pressure is far from saturation, and the moisture in the air can continue to evaporate. However, people will feel humid in autumn because the water vapor has reached saturation, and the moisture in the air cannot evaporate and will condense into water. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a humidity control system for a steam oven that can detect the humidity of the inner cavity and achieve precise humidity control, in light of the above-mentioned existing technology.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: The humidity control system of the steam oven includes an inner cavity, an air guide plate assembly for exhaust is installed on the top of the inner cavity, a hot air fan baffle is provided on the back or side of the inner cavity, a hot air chamber is formed on the outer side of the hot air fan baffle, a hot air outlet and a return air inlet are opened on the hot air fan baffle, a heating tube and a fan blade are installed in the hot air chamber, characterized in that: an air inlet channel is provided on the outer side of the hot air chamber, the air inlet of the air inlet channel is connected to the external air of the steam oven, the air outlet of the air inlet channel is connected to the interior of the hot air chamber, the air inlet channel has a first detection port that can detect the external air pressure, the hot air chamber has a second detection port that can detect the pressure in the fan blade outlet area, and a differential pressure sensor with a first pressure measuring port and a second pressure measuring port is installed on the outside of the inner cavity, the first pressure measuring port is connected to the first detection port, and the second pressure measuring port is connected to the second detection port.

[0007] Preferably, an air valve is installed on the outside of the inner liner. The air inlet of the air valve is connected to the outside air of the steam oven, and the air outlet of the air valve is connected to the air inlet of the air inlet channel. The system also includes a controller that receives the output signal from a differential pressure sensor and controls the opening and closing of the air valve accordingly. When the differential pressure sensor detects that the humidity in the inner liner is too high, the controller controls the air valve to open.

[0008] The fan blades can have various structures. Preferably, the fan blades include a rear base, a front base, and blades. The front side of the rear base has radially distributed first ribs, and the rear side of the front base has radially distributed second ribs. The first and second ribs are distributed circumferentially and correspond to each other. The rear base and the front base are aligned, and the first ribs and their corresponding second ribs collide. An air gap between the rear base and the front base forms an airflow channel. The central area of ​​the rear base has an airflow channel inlet, and the outer peripheral edges of the rear base and the front base form an airflow channel outlet. The blades are located on the front side of the front base and are distributed circumferentially. In this way, when the air valve is opened, outside air passes through the air inlet channel, through the airflow channel inlet in the central area of ​​the rear base, enters the negative pressure zone between the rear base and the front base, and flows out from the airflow channel outlet. Finally, it enters the inner liner through the air outlet of the hot air blower baffle, thereby squeezing out the water vapor in the inner liner and achieving forced dehumidification.

[0009] To ensure smoother airflow, the edge of the rear base is provided with a guide portion that aligns the airflow channel's outlet angle with the gap between the fan blades and the inner wall.

[0010] Preferably, the second detection port is directly opposite the outer peripheral wall of the rear base. In this way, the second detection port is close to the air outlet area of ​​the fan blade.

[0011] Preferably, the hot air blower baffle is an inner liner back plate, and an inner liner rear fixing plate is provided on the back of the hot air blower baffle, forming the hot air chamber between the hot air blower baffle and the inner liner rear fixing plate.

[0012] To ensure the accuracy of the differential pressure sensor detection, a temperature sensor capable of detecting the temperature of the hot air chamber is installed on the rear fixing plate of the inner liner.

[0013] The air guide plate assembly can have various structures. Preferably, the air guide plate assembly includes an air guide plate, a guide fan, and a motor. The guide fan is located inside the air guide plate and rotates under the drive of the motor. The air guide plate has an air inlet and an air outlet. The air inlet is connected to the exhaust port of the inner liner, and the air outlet is connected to the outside of the steam oven.

[0014] To improve the forced dehumidification effect of the air guide plate assembly, the air inlet of the air guide plate includes a first air inlet and a second air inlet, and the exhaust port of the inner liner includes a first exhaust port and a second exhaust port. The first exhaust port is connected to the first air inlet through a first exhaust pipe, and the second exhaust port is connected to the second air inlet through a second exhaust pipe. The first exhaust port is located on the upper part of the hot air blower baffle, and the second exhaust port is located on the lower part of the inner liner sidewall.

[0015] Further preferably, the first air inlet and the second inlet are located above the guide fan. Because the area above the guide fan is a negative pressure zone, it creates a suction effect on the water vapor inside the inner tank, achieving forced dehumidification.

[0016] In order to enable the fan blades to rotate smoothly, a hot air blower that drives the fan blades to rotate is installed on the back of the hot air chamber.

[0017] Compared with the prior art, the advantages of the present invention are as follows: The humidity control system of the steam oven forms a first air duct system through the hot air outlet and return air inlet on the hot air fan baffle, and forms a second air duct system with the air inlet channel, fan blades and hot air fan baffle. Through the combined action of the first and second air duct systems, the air volume of the hot air fan in the inner liner is greatly increased. In addition, the fan blades and air guide plate assembly in the hot air chamber form a dual-channel forced dehumidification, which greatly improves the dehumidification speed. Moreover, the humidity of the inner liner can be calculated in real time through the signal feedback of the differential pressure sensor, so as to achieve precise humidity control. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a steam oven according to an embodiment of the present invention;

[0019] Figure 2 for Figure 1 A schematic diagram of the steam oven from another angle;

[0020] Figure 3 for Figure 1 The diagram shows a cross-sectional view of the steam oven.

[0021] Figure 4 for Figure 2 An enlarged schematic diagram of part A in the middle;

[0022] Figure 5 This is a schematic diagram of the fan blade structure according to an embodiment of the present invention;

[0023] Figure 6 for Figure 5 A schematic diagram of the fan blade from another angle;

[0024] Figure 7 for Figure 5 An exploded view of the fan blades shown.

[0025] Figure 8 for Figure 5 An exploded view of the fan blade from another angle. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] like Figures 1 to 4 As shown, with Figure 2The direction indicated by arrow B is rearward. In this embodiment, the humidity control system of the steam oven includes an inner cavity 1. An upper mounting plate 14 is installed on the top of the inner cavity 1. An air guide plate assembly 2 for exhaust is installed on the upper mounting plate 14. The back panel of the inner cavity is a hot air blower baffle 3. A rear fixing plate 10 for the inner cavity is located on the back of the hot air blower baffle 3. A hot air chamber 4 is formed between the hot air blower baffle 3 and the rear fixing plate 10. A hot air outlet 31 and a return air inlet 32 ​​are opened on the hot air chamber 4. A heating pipe 5 and a fan blade 6 are installed inside the hot air chamber 4. A hot air blower 13 that drives the fan blade 6 is installed on the back of the hot air chamber 4. To detect the temperature inside the hot air chamber 4, a temperature sensor 11 is installed on the rear fixing plate 10. The temperature used in the following conversion of humidity and pressure difference is the temperature detected by this temperature sensor 11.

[0028] The air guide plate assembly 2 includes an air guide plate 21, a guide fan 22, and a motor 23. The guide fan 22 is located inside the air guide plate 21 and rotates under the drive of the motor 23. The air guide plate 21 has an air inlet and an air outlet. The air inlet is connected to the inner liner exhaust port, and the air outlet is connected to the outside of the steam oven. In this embodiment, the air inlet of the air guide plate 21 includes a first air inlet 211 and a second air inlet 212. Because there is a negative pressure zone above the guide fan 22, the first air inlet 211 and the second air inlet 212 are located above the guide fan 22. The inner liner exhaust ports include a first exhaust port 121 and a second exhaust port 122. The first exhaust port 121 is connected to the first air inlet 211 via a first exhaust pipe (not shown in the figure), and the second exhaust port 122 is connected to the second air inlet 212 via a second exhaust pipe (not shown in the figure). The first exhaust port 121 is located on the upper part of the hot air blower baffle 3, and the second exhaust port 122 is located on the lower part of the side wall of the inner liner 1. During operation, the motor 23 drives the guide fan 22 to rotate, and the water vapor in the inner liner 1 is drawn outward to form a forced dehumidification effect. That is, the air guide plate duct system constitutes one of the channels for forced dehumidification.

[0029] In this embodiment, the rear of the hot air chamber 4 is provided with an air inlet channel 7. An air valve 9 is installed outside the inner liner 1. The air inlet of the air valve 9 faces the rear of the entire machine and is connected to the external air of the steam oven. The air outlet of the air valve 9 faces downward and is connected to the air inlet of the air inlet channel 7. That is, the air inlet of the air inlet channel 7 is connected to the external air of the steam oven through the air valve 9, and the air outlet of the air inlet channel 7 is connected to the interior of the hot air chamber 4. The air inlet channel 7 has a first detection port 71, which is located at the upper part of the air inlet channel 7 near the air inlet of the air inlet channel 7. Therefore, the first detection port 71 is a low-pressure detection port that can detect the external air pressure. The hot air chamber 4 has a second detection port 41, which is a high-pressure detection port used to detect the pressure in the fan blade outlet area.

[0030] In this embodiment, a differential pressure sensor 8 is installed on the upper mounting plate 14. The differential pressure sensor 8 has a first pressure measuring port 81 and a second pressure measuring port 82. The first pressure measuring port 81 is connected to the first detection port 71, and the second pressure measuring port 82 is connected to the second detection port 41. The controller (not shown in the figure) can receive the output signal of the differential pressure sensor 8 and control the opening and closing of the air valve 9 accordingly based on the received signal. Since the first detection port 71 is a low-pressure detection port and the second detection port 41 is a high-pressure detection port, under the condition that the speed and temperature of the hot air blower are constant, the pressure difference caused by the different relative humidity results in different pressures. The pressure difference leads to different pressure differences at different positions in the inner tank, and the corresponding humidity value is calculated by converting the pressure difference.

[0031] After fixing the speed of the hot air blower 13, keep the temperature constant. When the humidity in the inner tank is at its maximum (the steam generator works for a long time until the pressure difference no longer changes), the pressure difference value at this time is recorded as 100% humidity (this 100% humidity is not the actual humidity, but the maximum humidity in the inner tank).

[0032] After the hot air blower's speed is fixed at 13, the temperature is maintained constant. When the humidity inside the inner tank is at its minimum (when the heating element in the inner tank operates intermittently for an extended period until the pressure difference no longer changes), this pressure difference value is recorded as 0% humidity (this 0% humidity is not the actual humidity, but rather the minimum humidity corresponding to the inner tank). Dividing the maximum and minimum pressure differences into 100 equal parts, the corresponding relative humidity for different pressure differences can be determined. For example, if the pressure difference is 56 Pa when the humidity inside the tank is at its maximum and 76 Pa when the humidity is at its minimum, then when the pressure difference is 66 Pa, the humidity is 50%.

[0033] Following the above testing method, the maximum and minimum pressure differences corresponding to each temperature point and fan speed (30℃~230℃, the maximum temperature range achievable in the inner tank) were measured. These values ​​were then divided into 100 equal parts to form a database. When the differential pressure sensor 8 detects the pressure difference value, it compares it with the data in the database and feeds the comparison result back to the controller. The controller then controls the steam generator or the gas valve 9 to operate, controlling humidification or dehumidification, thereby achieving precise humidity control.

[0034] like Figures 5 to 8As shown, the fan blade 6 in this embodiment includes a rear base 61, a front base 62, and blades 63. The front side of the rear base 61 is provided with radially distributed first ribs 611, and the rear side of the front base 62 is provided with radially distributed second ribs 621. The first ribs 611 and the second ribs 621 are distributed circumferentially and correspond to each other. The rear base 61 and the front base 62 are aligned and the first ribs 611 and the corresponding second ribs 621 collide. The air gap between the rear base 61 and the front base 62 forms an airflow channel 64. The central area of ​​the rear base 61 has an airflow channel inlet 641, which is the fan blade air inlet. The outer peripheral edges of the rear base 61 and the front base 62 form an airflow channel outlet 642, which is the fan blade air outlet. The blades 63 are disposed on the front side of the front base 62 and distributed circumferentially. The blades 63 constitute the sweeping blades. In order to make the air outlet of the fan blade smoother, the edge of the rear base 61 is formed with a guide part 612 to align the air outlet angle of the airflow channel 64 with the gap between the fan blade and the inner wall.

[0035] like Figure 2 As shown, the second detection port 41 is directly opposite the outer peripheral wall of the rear base 61, that is, the second detection port 41 is close to the fan blade air outlet, so that the second detection port 41 can better reflect the pressure of the fan blade air outlet. Since the air speed at the fan blade air outlet is relatively fast, the second detection port 41 forms a high-pressure detection port.

[0036] When the steam oven is working, the hot air blower 13 rotates, driving the blades 63 to rotate. The blades 63 expel the air in the middle area of ​​the fan blades 6, creating negative pressure. The air in the inner cavity 1 enters the negative pressure area through the return air vent 32 in the middle of the hot air blower baffle 3. The heating tubes 5 around the fan blades 6 heat the air, and then it is blown out through the hot air outlet 31, returning to the inner cavity 1 to heat the food. This hot air circulation system constitutes the first air duct system.

[0037] When the differential pressure sensor 8 detects excessive humidity in the inner liner 1, the controller opens the air valve 9, causing the hot air blower 13 to rotate the fan blades 6. The ribs between the front base 62 and the rear base 61 also rotate with the fan blades 6, expelling the air from the gap between the front base 62 and the rear base 61 and creating negative pressure. At this time, the front base 62 has no openings except for the central hole which needs to mate with the fan shaft. Air cannot enter the negative pressure gap area between the two bases, i.e., the airflow channel 64, from the front base 62 of the fan blades 6. The airflow channel outlet 642, i.e., the fan blade outlet, is formed around the two bases, so air cannot enter from the periphery of the two bases either. The rear base 61 has an airflow channel inlet 641 in the central area. Once the air valve 9 is opened, outside air enters the inlet of the air intake channel 7 through the air valve outlet, then passes through the airflow channel inlet 641 into the airflow channel 64, and finally enters the inner liner 1 through the hot air outlet 31 of the hot air blower baffle 3. The aforementioned air duct system is the second air duct system, which draws in dry outside air into the inner liner 1 and squeezes out the water vapor in the inner liner 1, thus achieving forced dehumidification.

[0038] In this embodiment, since the second air duct system shares the same air outlet as the first air duct system, when the hot air blower 13 rotates at a constant speed, the airflow at the hot air outlet 31 of the hot air blower baffle 3 is increased under the combined action of the two air duct systems. This increased airflow is beneficial for maintaining the uniformity of the temperature field inside the liner, as well as for the rapid cooking and dehumidification of food. The second air duct system constitutes another channel for forced dehumidification.

[0039] In this embodiment, since both the second air duct system and the air guide plate air duct system are forced dehumidification systems, the dehumidification speed can be greatly improved. Tests show that it only takes about one minute to reduce the humidity in the inner liner 1 from 90% to 5%. This increased dehumidification speed is beneficial for cooking many dishes, such as crispy chicken and dried lemon slices. If some foods require high humidity, the controller can close the gas valve 9 and extend the operating time of the steam generator, thus maintaining a higher humidity level in the inner liner 1.

[0040] The specification and claims of this invention use terms indicating direction, such as "front," "rear," "upper," "lower," "left," "right," "side," "top," and "bottom," to describe various exemplary structural parts and elements of the invention. However, these terms are used herein merely for ease of explanation and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in this invention can be arranged in different orientations, these terms indicating direction are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

Claims

1. A humidity control system for a steam oven, comprising an inner cavity (1), wherein a deflector assembly (2) for exhaust is installed on the top of the inner cavity (1), a hot air baffle (3) is provided on the back or side of the inner cavity (1), a hot air chamber (4) is formed on the outer side of the hot air baffle (3), a hot air outlet (31) and a return air inlet (32) are provided on the hot air baffle (3), and a heating tube (5) and a fan blade (6) are installed in the hot air chamber (4), characterized in that: The outer side of the hot air chamber (4) is provided with an air inlet channel (7). The air inlet of the air inlet channel (7) is connected to the external air of the steam oven, and the air outlet of the air inlet channel (7) is connected to the interior of the hot air chamber (4). The air inlet channel (7) has a first detection port (71) that can detect the external air pressure. The hot air chamber (4) has a second detection port (41) that can detect the pressure in the fan blade outlet area. A differential pressure sensor (8) with a first pressure measuring port (81) and a second pressure measuring port (82) is installed on the outside of the inner liner (1). The first pressure measuring port (81) is connected to the first detection port (71), and the second pressure measuring port (82) is connected to the second detection port (41). The fan blade (6) includes a rear base (61), a front base (62), and blades (63). The rear base (61) The front side of the front base (62) is provided with a radially distributed first rib (611), and the rear side of the front base (62) is provided with a radially distributed second rib (621). The first rib (611) and the second rib (621) are distributed circumferentially and correspond to each other. The rear base (61) and the front base (62) are aligned and the first rib (611) and the corresponding second rib (621) collide. The air gap between the rear base (61) and the front base (62) forms an airflow channel (64). The central area of ​​the rear base (61) has an airflow channel inlet (641), and the outer peripheral edges of the rear base (61) and the front base (62) form an airflow channel outlet (642). The blade (63) is provided on the front side of the front base (62) and is distributed circumferentially.

2. The humidity control system of the steam oven according to claim 1, characterized in that: An air valve (9) is installed outside the inner liner (1). The air inlet of the air valve (9) is connected to the air outside the steam oven, and the air outlet of the air valve (9) is connected to the air inlet of the air inlet channel (7). The air valve (9) also includes a controller that can receive the output signal of the differential pressure sensor (8) and control the opening and closing of the air valve (9) according to the received signal.

3. The humidity control system of the steam oven according to claim 1, characterized in that: The edge of the rear base (61) is formed with a guide portion (612) that aligns the air outlet angle of the airflow channel (64) with the gap between the fan blade and the inner wall.

4. The humidity control system of the steam oven according to claim 1, characterized in that: The second detection port (41) is directly opposite the outer peripheral wall of the rear base (61).

5. The humidity control system of the steam oven according to claim 1, characterized in that: The hot air blower baffle (3) is the inner liner back plate, and an inner liner rear fixing plate (10) is provided on the back of the hot air blower baffle (3). The hot air chamber (4) is formed between the hot air blower baffle (3) and the inner liner rear fixing plate (10).

6. The humidity control system of the steam oven according to claim 5, characterized in that: A temperature sensor (11) capable of detecting the temperature of the hot air chamber (4) is installed on the inner liner rear fixing plate (10).

7. The humidity control system of the steam oven according to any one of claims 1 to 6, characterized in that: The air guide plate assembly (2) includes an air guide plate (21), a fan (22) and a motor (23). The fan (22) is located inside the air guide plate (21) and rotates under the drive of the motor (23). The air guide plate (21) has an air inlet and an air outlet. The air inlet is connected to the inner liner exhaust port, and the air outlet is connected to the outside of the steam oven.

8. The humidity control system of the steam oven according to claim 7, characterized in that: The air inlet of the air guide plate (21) includes a first air inlet (211) and a second air inlet (212). The exhaust port of the inner liner includes a first exhaust port (121) and a second exhaust port (122). The first exhaust port (121) is connected to the first air inlet (211) through a first exhaust pipe. The second exhaust port (122) is connected to the second air inlet (212) through a second exhaust pipe. The first exhaust port (121) is located on the upper part of the hot air blower baffle (3), and the second exhaust port (122) is located on the lower part of the side wall of the inner liner (1).

9. The humidity control system of the steam oven according to claim 1, characterized in that: A hot air blower (13) that drives the fan blades (6) to rotate is installed on the back of the hot air chamber (4).

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