Centrifugal fan and steaming oven

Abstract

The invention relates to the technical field of fans, in particular to a centrifugal fan and a steaming and baking oven, and aims to solve the problem that in the prior art, the adjustable range of the air conveying effect of a centrifugal fan is limited, and different use requirements cannot be met. In order to achieve the purpose, the centrifugal fan comprises a rotating disc, a plurality of first blades, a plurality of second blades and a switching structure, and the rotating disc is arranged to be capable of rotating; the multiple first blades are connected with the rotating disc and arranged in the circumferential direction of the rotating disc, and a first channel is defined by the multiple first blades; the second blades are connected with the rotating disc and arranged on the peripheries of the first blades, and an annular second channel is defined by the second blades and the first blades; the switching structure is arranged to selectively and directly guide gas outside the centrifugal fan to at least one of the first channel and the second channel from the gas inlet of the centrifugal fan. According to the centrifugal fan, the adjustable range of the air conveying effect of the centrifugal fan is enlarged, and various different use requirements can be met.

Description

Technical Field

[0001] The invention relates to the technical field of fans, and in particular provides a centrifugal fan and a steam oven. Background Art

[0002] A centrifugal fan is a mechanical device that converts mechanical energy into gas kinetic energy and pressure energy through a rotating impeller, thereby achieving gas transportation. When the motor drives the impeller to rotate, the blades installed on the impeller exert centrifugal force on the gas entering the centrifugal fan, causing the gas to be thrown out along the radius of the impeller and gain speed and pressure in the process.

[0003] Existing centrifugal fans usually adjust the gas delivery effect by controlling the speed of the impeller, but the adjustable range is limited and cannot meet different usage requirements when applied. For example, when applied to a steam oven, steam and exhaust gas are generated in the cavity of the steam oven during the cooking process. As the steam and exhaust gas accumulate, the pressure in the cavity will gradually increase and the temperature will fluctuate. Therefore, it is usually necessary to use a centrifugal fan to discharge the steam and exhaust gas in time. However, since the centrifugal fan has a limited adjustable range for the exhaust volume, the temperature and pressure in the cavity fluctuate greatly, affecting the cooking effect and cooking efficiency of the food.

[0004] Accordingly, the art needs a new centrifugal fan and steam oven to solve the above problems. Summary of the invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem that the centrifugal fan in the prior art has a limited adjustable range for the gas conveying effect and cannot meet different usage requirements.

[0006] In a first aspect, the present invention provides a centrifugal fan, comprising: a turntable, which is configured to be able to rotate; a plurality of first blades, which are connected to the turntable and arranged along the circumference of the turntable, and the plurality of first blades are arranged to form a first channel; a plurality of second blades, which are connected to the turntable and arranged on the outer circumference of the plurality of first blades, and the plurality of second blades and the plurality of first blades are arranged to form an annular second channel; and a switching structure, which is configured to be able to selectively guide gas outside the centrifugal fan directly from the gas inlet of the centrifugal fan to at least one of the first channel and the second channel.

[0007] In the case of adopting the above technical solution, since the first blade and the second blade are both connected to the turntable and the turntable can rotate, the first blade and the second blade can both produce a pressurization and acceleration effect on the gas, and since the blades arranged at different diameters have different pressurization and acceleration effects on the gas, the blade arrangements with different numbers of circles also have different pressurization and acceleration effects on the gas. Therefore, the gas outside the centrifugal fan is directly guided to at least one of the first channel and the second channel through the switching structure, so that the centrifugal fan can achieve a variety of gas delivery states, including most of the gas is pressurized and accelerated only by the first blade, all of the gas is pressurized and accelerated only by the second blade, and all of the gas passes through the first At least two of the following methods are used: after the blade boost acceleration, the gas is boosted and accelerated by the second blade; after part of the gas is boosted and accelerated by the second blade, part of the gas is boosted and accelerated by the first blade and then by the second blade; after part of the gas is boosted and accelerated by the first blade, part of the gas is boosted and accelerated by the second blade, thereby obtaining different gas delivery effects, increasing the adjustable range of the centrifugal fan for the gas delivery effect, and being able to meet a variety of different usage requirements; when the centrifugal fan is applied to a steam oven, the centrifugal fan can switch to different gas delivery states according to the different exhaust requirements of the steam oven, thereby reducing the temperature and pressure fluctuations in the cavity of the steam oven, and improving the cooking effect and cooking efficiency of food.

[0008] In a specific embodiment of the above-mentioned centrifugal fan, the length of the first blade along the axial direction of the turntable is greater than the length of the second blade along the axial direction of the turntable, and the first blade extends beyond an end of the second blade along the axial direction of the turntable away from the gas inlet.

[0009] When the above technical solution is adopted, when the switching structure guides the gas to the first channel, the first blade rotates to accelerate the gas in the first channel and changes the axial airflow into a radial airflow toward the periphery. The radial airflow is discharged from the gaps between the plurality of first blades. Under the action of centrifugal force, most of the gas in the first channel is discharged from the end away from the gas inlet. Since the first blade extends to the end of the second blade away from the gas inlet along the axial direction of the turntable, most of the gas only passes through the acceleration and pressurization effect of the first blade, and no longer passes through the second blade after being discharged from the gap between the first blades, thereby achieving a relatively smooth gas delivery effect. When the switching structure guides the gas to the second channel, the second blade rotates to accelerate the gas in the second channel. , and changes the axial airflow into a radial airflow toward the periphery, and the radial airflow is discharged from the gaps between the multiple second blades. Since the working ability of the blades on the gas is in a quadratic relationship with the diameter of the blade arrangement and in a linear relationship with the length of the blade along the axial direction of the turntable, the diameter of the blade arrangement has a stronger ability to boost the gas. After the switching structure guides the gas to the second channel, it can achieve a more efficient and rapid gas delivery effect than guiding the gas to the first channel; when the switching structure guides the gas to the first channel and the second channel, part of the gas enters the first channel and part of the gas enters the second channel, and the sum of the above two gas delivery effects can be obtained. Compared with guiding the gas to the second channel, a more efficient and rapid gas delivery effect can be achieved.

[0010] In a specific embodiment of the centrifugal fan, the first blade and the second blade have the same length along the axial direction of the rotating disk.

[0011] When the above technical solution is adopted, when the switching structure guides the gas to the first channel, the first blade rotates to accelerate the gas in the first channel, and changes the axial airflow into a radial airflow toward the periphery. After the radial airflow is discharged from the gaps between the multiple first blades, it is further accelerated by the rotating second blades, and then discharged from the gaps between the multiple second blades, thereby achieving an efficient and rapid gas delivery effect; when the switching structure guides the gas to the second channel, the second blade rotates to accelerate the gas in the second channel, and changes the axial airflow into a radial airflow toward the periphery. The radial airflow is discharged from the gaps between the multiple second blades, thereby achieving a smoother gas delivery effect compared to guiding the gas to the first channel; when the switching structure guides the gas to the first channel and the second channel, part of the gas enters the first channel and part of the gas enters the second channel, thereby achieving the sum of the above two gas delivery effects, thereby achieving a more efficient and rapid gas delivery effect compared to guiding the gas to the first channel.

[0012] In a specific embodiment of the centrifugal fan, the cross-sections of the first blade and the second blade along the radial direction of the rotating disk are both arc-shaped, the arc-shaped convex surface of the first blade is the windward surface, and the arc-shaped concave surface of the second blade is the windward surface.

[0013] When the above technical solution is adopted, the gas is accelerated by the convex surface of the first blade and then enters the concave surface of the second blade, which produces counter-pressure and secondary centrifugation on the gas, thereby increasing the gas pressure.

[0014] In a specific embodiment of the centrifugal fan, the plurality of second blades are the same in number as the plurality of first blades and are arranged in a one-to-one correspondence.

[0015] When the above technical solution is adopted, the airflow thrown out from the first blade directly enters the corresponding concave surface of the second blade, which can effectively reduce flow losses and improve gas transportation efficiency.

[0016] In a specific embodiment of the above-mentioned centrifugal fan, the switching structure includes a first air duct, a second air duct, a first valve and a second valve, the first air duct is connected to the first channel, the second air duct is connected to the second channel, the first valve is used to control the connection or disconnection between the first air duct and the first channel, and the second valve is used to control the connection or disconnection between the second air duct and the second channel.

[0017] When the above technical solution is adopted, by controlling the connection or disconnection between the first air duct and the first channel by the first valve, and controlling the connection or disconnection between the second air duct and the second channel by the second valve, it is possible to selectively guide the gas outside the centrifugal fan directly from the gas inlet of the centrifugal fan to at least one of the first channel and the second channel.

[0018] In a specific embodiment of the above-mentioned centrifugal fan, the turntable includes a first baffle and a second baffle connected to each other, the first blade is connected to the first baffle, the second blade is connected to the second baffle, the first baffle covers an end of the first channel away from the gas inlet, and the second baffle covers an end of the second channel away from the gas inlet.

[0019] When the above technical solution is adopted, the first baffle can block the axial airflow in the first channel from continuing to flow axially, thereby assisting the first blade to change the axial airflow into a radial airflow, thereby reducing flow losses; the second baffle can block the axial airflow in the second channel from continuing to flow axially, thereby assisting the second blade to change the axial airflow into a radial airflow, thereby reducing flow losses; since the lengths of the first blade and the second blade are not equal, the turntable is configured to include a first baffle and a second baffle connected to each other.

[0020] In a specific embodiment of the centrifugal fan, the rotating disk covers the ends of the first channel and the second channel away from the gas inlet.

[0021] When the above technical solution is adopted, the turntable can block the axial airflow in the first channel and the second channel from continuing to flow axially, thereby assisting the first blade and the second blade to change the axial airflow into radial airflow, reducing flow losses.

[0022] In a specific embodiment of the above-mentioned centrifugal fan, the centrifugal fan also includes a plurality of third blades, the plurality of third blades are connected to the turntable and are arranged on the outer periphery of the plurality of second blades, and the plurality of third blades and the plurality of second blades are arranged to form an annular third channel; the switching structure is configured to be able to selectively guide the gas outside the centrifugal fan directly from the gas inlet of the centrifugal fan to at least one of the first channel, the second channel and the third channel.

[0023] When adopting the above technical solution, a third channel is formed by setting the third blade and a circle of boost acceleration structure is added, so that the centrifugal fan can switch between more gas delivery states, further increasing the adjustable range of the centrifugal fan for the gas delivery effect, thereby being able to meet more usage requirements.

[0024] In a second aspect, the present invention further provides a steam oven, the steam oven comprising a centrifugal fan.

[0025] When the above technical solution is adopted, since the centrifugal fan can switch different gas delivery states according to the different exhaust requirements of the steam oven, the temperature and pressure fluctuations in the cavity of the steam oven can be reduced, thereby improving the cooking effect and cooking efficiency of food.

[0026] Compared with the prior art, the centrifugal fan provided by the present invention has the following beneficial effects: since the first blade and the second blade are both connected to the turntable and the turntable can rotate, the first blade and the second blade can both produce a pressurization and acceleration effect on the gas, and since the blades are arranged at different diameters to have different pressurization and acceleration effects on the gas, the blades arranged with different numbers of circles have different pressurization and acceleration effects on the gas. Therefore, the gas outside the centrifugal fan is directly guided to at least one of the first channel and the second channel through the switching structure, so that the centrifugal fan can achieve a variety of gas delivery states, including most of the gas is pressurized and accelerated only by the first blade, all of the gas is pressurized and accelerated only by the second blade, and all of the gas is pressurized and accelerated only by the second blade. At least two of the following methods are adopted: part of the gas is pressurized and accelerated by the first blade and then by the second blade, part of the gas is pressurized and accelerated by the second blade, part of the gas is pressurized and accelerated by the first blade and then by the second blade, and part of the gas is pressurized and accelerated by the first blade and part of the gas is pressurized and accelerated by the second blade, thereby obtaining different gas conveying effects, increasing the adjustable range of the centrifugal fan for the gas conveying effect, and being able to meet a variety of different usage requirements; when the centrifugal fan is applied to a steam oven, the centrifugal fan can switch to different gas conveying states according to the different exhaust requirements of the steam oven, thereby reducing the temperature and pressure fluctuations in the cavity of the steam oven, and improving the cooking effect and cooking efficiency of food. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0028] Figure 1 is a partial cross-sectional view of a first embodiment of the centrifugal fan of the present invention;

[0029] Figure 2 is a structural schematic diagram of a first embodiment of the centrifugal fan of the present invention;

[0030] Figure 3 is a structural schematic diagram of the first embodiment of the centrifugal fan of the present invention from another angle;

[0031] Figure 4 is a gas flow diagram of a first embodiment of the centrifugal fan of the present invention;

[0032] Figure 5 is a structural schematic diagram of a second embodiment of the centrifugal fan of the present invention;

[0033] Figure 6 is a structural schematic diagram of the second embodiment of the centrifugal fan of the present invention from another angle;

[0034] Figure 7 is a structural schematic diagram of a third embodiment of the centrifugal fan of the present invention;

[0035] Reference numerals:

[0036] 1-turntable, 2-first blade, 3-second blade, 4-switching structure, 5-first channel, 6-second channel, 7-third blade, 8-third channel, 9-first connecting piece, 11-first baffle, 12-second baffle, 41-first air duct, 42-second air duct, 43-first valve, 44-second valve. DETAILED DESCRIPTION

[0037] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not used to limit the scope of protection of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0038] It should be noted that, in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "front", "back", "top", "bottom", "vertical", "horizontal", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the relevant devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0039] In addition, it should be noted that in the description of the present invention, ordinal numbers such as "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In addition, in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0040] Based on the problem pointed out in the background technology that the centrifugal fan in the prior art has a limited adjustable range of gas conveying effect and cannot meet different usage requirements, the present invention aims to obtain different gas conveying effects by setting a first blade, a second blade and a switching structure, thereby increasing the adjustable range of the gas conveying effect of the centrifugal fan and being able to meet a variety of different usage requirements.

[0041] See first Figure 1 and Figure 2 , Figure 1is a partial cross-sectional view of a first embodiment of the centrifugal fan of the present invention, Figure 2 Schematic diagram of the structure of the first embodiment of the centrifugal fan of the present invention. Figure 1 and Figure 2 As shown, the centrifugal fan of the present invention includes a turntable 1, a plurality of first blades 2, a plurality of second blades 3 and a switching structure 4, the turntable 1 is configured to be able to rotate; the plurality of first blades 2 are connected to the turntable 1 and are arranged along the circumference of the turntable 1, and the plurality of first blades 2 are arranged to form a first channel 5; the plurality of second blades 3 are connected to the turntable 1 and are arranged on the outer periphery of the plurality of first blades 2, and the plurality of second blades 3 and the plurality of first blades 2 are arranged to form an annular second channel 6; the switching structure 4 is configured to be able to selectively guide the gas outside the centrifugal fan directly from the gas inlet of the centrifugal fan to at least one of the first channel 5 and the second channel 6. Since the first blade 2 and the second blade 3 are both connected to the turntable 1, and the turntable 1 can rotate, the first blade 2 and the second blade 3 can both produce a pressurization and acceleration effect on the gas, and since the blades are arranged at different diameters with different pressurization and acceleration effects on the gas, the blades arranged with different numbers of circles have different pressurization and acceleration effects on the gas. Therefore, the gas outside the centrifugal fan is directly guided to at least one of the first channel 5 and the second channel 6 through the switching structure 4, so that the centrifugal fan can achieve a variety of gas delivery states, including most of the gas is pressurized and accelerated only by the first blade 2, all the gas is pressurized and accelerated only by the second blade 3, and all the gas is pressurized and accelerated by the first blade 2. After acceleration, the gas is pressurized and accelerated by the second blade 3, part of the gas is pressurized and accelerated by the second blade 3, and part of the gas is pressurized and accelerated by the first blade 2 and then pressurized and accelerated by the second blade 3, and part of the gas is pressurized and accelerated by the first blade 2 and part of the gas is pressurized and accelerated by the second blade 3, thereby obtaining different gas delivery effects, increasing the adjustable range of the centrifugal fan for the gas delivery effect, and being able to meet a variety of different usage requirements; when the centrifugal fan is applied to a steam oven, the centrifugal fan can switch to different gas delivery states according to the different exhaust requirements of the steam oven, thereby reducing the temperature and pressure fluctuations in the cavity of the steam oven, and improving the cooking effect and cooking efficiency of food.

[0042] It should be noted that the gas inlet is located at Figure 1 The bottom of the centrifugal fan in the present invention does not specifically limit the structure of the gas inlet, as long as the gas outside the centrifugal fan can enter the inside of the centrifugal fan through the gas inlet.

[0043] Furthermore, the switching structure 4 includes a first air duct 41, a second air duct 42, a first valve 43 and a second valve 44. The first air duct 41 is connected to the first channel 5, and the second air duct 42 is connected to the second channel 6. The first valve 43 is used to control the connection or disconnection between the first air duct 41 and the first channel 5, and the second valve 44 is used to control the connection or disconnection between the second air duct 42 and the second channel 6.

[0044] It should be noted that, regarding the first valve 43, the first valve 43 may be a butterfly valve, a ball valve, etc., and the present invention does not specifically limit the type of the first valve 43, as long as the first valve 43 can control the connection or disconnection between the first air duct 41 and the first channel 5. Regarding the second valve 44, since the second air duct 42 is annular, the second valve 44 may be a shutter valve, and the second valve 44 may be arranged in the second air duct 42 or at both ends of the second air duct 42; a valve mounting plate may also be arranged in the second air duct 42 or at both ends of the second air duct 42, and a mounting hole is opened on the valve mounting plate, and the second valve 44 is arranged in the mounting hole. The number of mounting holes and second valves 44 may be one or more. In this case, the second valve 44 may be a butterfly valve or a ball valve, etc., as long as the second valve 44 can control the connection or disconnection between the second air duct 42 and the second channel 6.

[0045] Furthermore, the turntable 1 covers the ends of the first channel 5 and the second channel 6 away from the gas inlet. The turntable 1 can block the axial airflow in the first channel 5 and the second channel 6 from continuing to flow axially, thereby assisting the first blade 2 and the second blade 3 to change the axial airflow into a radial airflow, thereby reducing flow losses.

[0046] Possibly, the centrifugal fan may further include a first connecting member 9, which is connected to one end of the plurality of first blades 2 in the axial direction of the turntable 1 close to the gas inlet, and is used to prevent the first blades 2 from falling off due to the outward deviation of one end of the first blades 2 in the axial direction of the turntable 1 close to the gas inlet when the first blades 2 rotate for a long time, so as to improve the reliability of the connection of the first blades 2. The centrifugal fan may also include a second connecting member, which is connected to one end of the second blades 3 in the axial direction of the turntable 1 close to the gas inlet, and the second connecting member is connected to the first connecting member 9 through a plurality of connecting rods, so as to improve the reliability of the connection of the second blades 3.

[0047] See below Figure 1-Figure 4 , Figure 3 is a structural schematic diagram of the first embodiment of the centrifugal fan of the present invention from another angle, Figure 4 Schematic diagram of gas flow of the first embodiment of the centrifugal fan of the present invention. Figure 1-Figure 4As shown, as a possible implementation, the length of the first blade 2 along the axial direction of the turntable 1 is greater than the length of the second blade 3 along the axial direction of the turntable 1, and the first blade 2 extends to the outside of the end of the second blade 3 along the axial direction of the turntable 1 away from the gas inlet. When the switching structure 4 guides the gas to the first channel 5, the first blade 2 rotates to accelerate the gas in the first channel 5, and changes the axial airflow into a radial airflow toward the periphery. The radial airflow is discharged from the gaps between the multiple first blades 2. Under the action of centrifugal force, most of the gas in the first channel 5 is discharged from the end away from the gas inlet. Since the first blade 2 extends to the outside of the end of the second blade 3 along the axial direction of the turntable 1 away from the gas inlet, most of the gas only passes through the acceleration and pressurization effect of the first blade 2, and no longer passes through the second blade 3 after being discharged from the gaps between the first blades 2, thereby achieving a relatively smooth gas delivery effect. The gas flow at this time is as shown in FIG. Figure 4 As shown; when the switching structure 4 guides the gas to the second channel 6, the second blade 3 rotates to accelerate the gas in the second channel 6, and changes the axial airflow into a radial airflow toward the periphery. The radial airflow is discharged from the gaps between the plurality of second blades 3. Since the working capacity of the blades on the gas is in a quadratic relationship with the diameter of the blade arrangement and in a linear relationship with the axial length of the blade along the turntable 1, the diameter of the blade arrangement has a stronger ability to increase the pressure of the gas. After the switching structure 4 guides the gas to the second channel 6, compared with guiding the gas to the first channel 5, it can achieve a highly efficient and rapid gas delivery effect; when the switching structure 4 guides the gas to the first channel 5 and the second channel 6, part of the gas enters the first channel 5, and part of the gas enters the second channel 6, so that the above two gas delivery effects can be added together. Compared with guiding the gas to the second channel 6, a more efficient and rapid gas delivery effect can be achieved.

[0048] Further, the turntable 1 includes a first baffle 11 and a second baffle 12 connected to each other, the first blade 2 is connected to the first baffle 11, the second blade 3 is connected to the second baffle 12, the first baffle 11 covers the end of the first channel 5 away from the gas inlet, and the second baffle 12 is annular and covers the end of the second channel 6 away from the gas inlet. The first baffle 11 can block the axial airflow in the first channel 5 from continuing to flow in the axial direction, thereby assisting the first blade 2 to change the axial airflow into a radial airflow, reducing flow losses; the second baffle 12 can block the axial airflow in the second channel 6 from continuing to flow in the axial direction, thereby assisting the second blade 3 to change the axial airflow into a radial airflow, reducing flow losses; since the lengths of the first blade 2 and the second blade 3 are not equal, the turntable 1 is configured to include the first baffle 11 and the second baffle 12 connected to each other.

[0049] See below Figure 5 and Figure 6 , Figure 5 is a structural schematic diagram of a second embodiment of the centrifugal fan of the present invention, Figure 6 FIG. 2 is a schematic structural diagram of the second embodiment of the centrifugal fan of the present invention from another angle. Figure 5 and Figure 6 As shown, as a possible implementation, the first blade 2 and the second blade 3 have the same length along the axial direction of the turntable 1. When the switching structure guides the gas to the first channel 5, the first blade 2 rotates to accelerate the gas in the first channel 5, and changes the axial airflow into a radial airflow toward the periphery. After the radial airflow is discharged from the gaps between the multiple first blades 2, it is further accelerated by the rotating second blade 3, and then discharged from the gaps between the multiple second blades 3, achieving an efficient and fast gas delivery effect; when the switching structure guides the gas to the second channel 6, the second blade 3 rotates to accelerate the gas in the second channel 6, and changes the axial airflow into a radial airflow toward the periphery. The radial airflow is discharged from the gaps between the multiple second blades 3, and compared with guiding the gas to the first channel 5, a relatively gentle gas delivery effect can be achieved; when the switching structure guides the gas to the first channel 5 and the second channel 6, part of the gas enters the first channel 5, and part of the gas enters the second channel 6, and the above two gas delivery effects can be added together, which can achieve a more efficient and fast gas delivery effect compared with guiding the gas to the first channel 5.

[0050] Optionally, the radial cross-sections of the first blade 2 and the second blade 3 along the rotating disk 1 are both arc-shaped, the arc-shaped convex surface of the first blade 2 is the windward surface, and the arc-shaped concave surface of the second blade 3 is the windward surface. After the gas is accelerated by the convex surface of the first blade 2, it enters the concave surface of the second blade 3, which produces counter-pressure and secondary centrifugation on the gas, thereby increasing the gas pressure. For example, Figure 6 As shown, when the first blade 2 and the second blade 3 rotate in the clockwise direction in the figure, the flow direction of the gas is shown by the arrow in the figure.

[0051] Optionally, the number of the plurality of second blades 3 is the same as the number of the plurality of first blades 2 and they are arranged in one-to-one correspondence. The airflow thrown out from the first blade 2 directly enters the concave surface of the corresponding second blade 3, which can effectively reduce flow loss and improve gas delivery efficiency.

[0052] See below Figure 7 , Figure 7 Schematic diagram of the structure of the third embodiment of the centrifugal fan of the present invention. Figure 7As shown, as a possible implementation, the centrifugal fan may further include a plurality of third blades 7, which are connected to the rotating disk 1 and arranged on the outer periphery of the plurality of second blades 3, and the plurality of third blades 7 and the plurality of second blades 3 are arranged to form a ring-shaped third channel 8; the switching structure 4 is configured to selectively guide the gas outside the centrifugal fan directly from the gas inlet of the centrifugal fan to at least one of the first channel 5, the second channel 6 and the third channel 8. By configuring the third blades 7, the third channel 8 is formed and a circle of boosting and accelerating structure is added, so that the centrifugal fan can switch to more gas delivery states, further increasing the adjustable range of the centrifugal fan on the gas delivery effect, and thus being able to meet more usage requirements.

[0053] It should be noted that the number of blade turns of the centrifugal fan can be greater, and those skilled in the art can adjust it according to usage requirements to obtain an adjustable range for different gas delivery effects.

[0054] The present invention also provides a steam oven, which includes a centrifugal fan and a cavity, and the cavity is used to steam and bake food. The gas inlet of the centrifugal fan is connected to the cavity, and the gas in the cavity, including steam and exhaust gas, can be discharged through the centrifugal fan. The centrifugal fan can switch different gas delivery states according to different exhaust requirements of the steam oven, thereby reducing the temperature and pressure fluctuations in the cavity of the steam oven, and improving the cooking effect and cooking efficiency of food. Exemplarily, when the air pressure in the cavity is low, the gas delivery state of the centrifugal fan can be controlled to be a gentle delivery state, and when the air pressure in the cavity is high, the gas delivery state of the centrifugal fan can be controlled to be an efficient and fast delivery state.

[0055] It should be noted that the above-mentioned embodiments are only used to illustrate the principles of the present invention and are not intended to limit the scope of protection of the present invention. Without departing from the principles of the present invention, those skilled in the art can adjust the above-mentioned embodiments so that the present invention can be applied to more specific application scenarios.

[0056] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A centrifugal fan, characterized in that: The centrifugal fan comprises: A turntable (1), wherein the turntable (1) is configured to be rotatable; a plurality of first blades (2), the plurality of first blades (2) being connected to the rotating disk (1) and arranged along the circumference of the rotating disk (1), the plurality of first blades (2) surrounding forming a first channel (5); a plurality of second blades (3), the plurality of second blades (3) being connected to the rotating disk (1) and arranged on the outer periphery of the plurality of first blades (2), the plurality of second blades (3) and the plurality of first blades (2) forming an annular second channel (6); A switching structure (4), wherein the switching structure (4) is configured to selectively guide gas outside the centrifugal fan directly from a gas inlet of the centrifugal fan to at least one of the first channel (5) and the second channel (6).

2. The centrifugal fan according to claim 1, characterized in that: The length of the first blade (2) along the axial direction of the turntable (1) is greater than the length of the second blade (3) along the axial direction of the turntable (1), and the first blade (2) extends beyond an end of the second blade (3) away from the gas inlet in the axial direction of the turntable (1).

3. The centrifugal fan according to claim 1, characterized in that: The first blade (2) and the second blade (3) have the same length along the axial direction of the rotating disk (1).

4. The centrifugal fan according to claim 3, characterized in that: The cross-sections of the first blade (2) and the second blade (3) along the radial direction of the rotating disk (1) are both arc-shaped, the arc-shaped convex surface of the first blade (2) is the windward surface, and the arc-shaped concave surface of the second blade (3) is the windward surface.

5. The centrifugal fan according to claim 4, characterized in that: The plurality of second blades (3) are the same in number as the plurality of first blades (2) and are arranged in one-to-one correspondence.

6. The centrifugal fan according to claim 1, characterized in that: The switching structure (4) comprises a first air duct (41), a second air duct (42), a first valve (43) and a second valve (44); the first air duct (41) is connected to the first channel (5), the second air duct (42) is connected to the second channel (6), the first valve (43) is used to control the connection or disconnection between the first air duct (41) and the first channel (5), and the second valve (44) is used to control the connection or disconnection between the second air duct (42) and the second channel (6).

7. The centrifugal fan according to claim 2, characterized in that: The turntable (1) comprises a first baffle (11) and a second baffle (12) which are connected to each other, the first blade (2) is connected to the first baffle (11), the second blade (3) is connected to the second baffle (12), the first baffle (11) covers an end of the first channel (5) away from the gas inlet, and the second baffle (12) covers an end of the second channel (6) away from the gas inlet.

8. The centrifugal fan according to claim 3, characterized in that: The rotating disk (1) covers the first channel (5) and the second channel (6) at one end away from the gas inlet.

9. The centrifugal fan according to claim 1, characterized in that: The centrifugal fan further comprises a plurality of third blades (7), the plurality of third blades (7) being connected to the rotating disk (1) and arranged on the outer periphery of the plurality of second blades (3), the plurality of third blades (7) and the plurality of second blades (3) forming an annular third channel (8); The switching structure (4) is configured to selectively guide the gas outside the centrifugal fan directly from the gas inlet of the centrifugal fan to at least one of the first channel (5), the second channel (6) and the third channel (8).

10. A steam oven, characterized in that: The steam oven comprises the centrifugal fan according to any one of claims 1 to 9.

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