A steam discharge device

Abstract

The present application provides a steam exhaust device for being installed on the exhaust port of the side wall of the inner container of a steam oven, the steam exhaust device has a steam inlet end and a steam exhaust end, the steam inlet end is communicated with the exhaust port, the steam exhaust device comprises an airflow accelerating assembly, the side wall of the steam exhaust device is provided with at least one air inlet, the air inlet is located upstream of the airflow accelerating assembly along the airflow direction, and the airflow accelerating assembly introduces external cold air through the air inlet. Compared with the prior art, the steam temperature in the exhaust pipe can be cooled, so that the environment of the kitchen is not humid and hot, the cabinet is not damaged, the noise can be reduced, the user experience can be improved, and no additional fan is needed, so that the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of cooking equipment technology, and in particular to a steam emission device. Background Technology

[0002] A steam oven is an electrical appliance that uses high-temperature steam to cook food. To ensure that the pressure inside the steam oven's inner chamber does not become excessive, a steam vent is usually provided on the inner chamber. The high-temperature steam generated inside the inner chamber is discharged through this vent into an exhaust channel located above the inner chamber, and then discharged outwards through this exhaust channel. The steam vent of the steam oven's exhaust channel is usually located at the front or top of the steam oven. If the temperature of the discharged steam is too high, it can easily burn users, damage surrounding cabinets, and also lead to a humid and hot kitchen environment, seriously affecting the user experience.

[0003] To reduce the temperature of exhaust steam, some existing technologies have incorporated cooling structures into the exhaust duct. For example, Chinese invention patent application CN202311046395.4 discloses a kitchen appliance with an exhaust duct for discharging steam from the steamer and a blower duct connected to it. A fan is installed in the blower duct, which blows cold air into the exhaust duct to disperse and cool the steam, thereby accelerating steam condensation, increasing exhaust speed, facilitating the removal of oil by the range hood, and preventing condensation on the walls and oil cups. However, the aforementioned technology has the following shortcomings: First, this solution introduces an additional fan as an active cooling component. The fan generates significant rotational and airflow noise during operation, significantly increasing the overall noise level of the steamer and degrading the user experience. Especially in a home kitchen, an environment sensitive to noise, the continuous operation of the fan can be unpleasant. Second, the introduction of the fan significantly increases the product's material and assembly costs. The fan itself needs to be purchased or manufactured, and it also requires supporting control circuits, power cords, and installation structures, which increases the overall cost and weakens the product's market competitiveness. Third, as a moving part, the fan operates in a high-temperature, high-humidity steam environment for extended periods, making it prone to reliability issues such as bearing wear, blade scaling, and motor moisture absorption, increasing the risk and cost of after-sales maintenance.

[0004] Therefore, how to effectively reduce the exhaust temperature and noise of the steam oven without adding extra power components (such as fans), while maintaining a compact structure and controllable cost, is a technical problem that urgently needs to be solved in the current steam oven technology field. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a steam discharge device that can reduce the temperature of discharged steam, in contrast to the prior art.

[0006] The second technical problem to be solved by the present invention is to provide a steam emission device that can reduce exhaust noise, in contrast to the prior art.

[0007] The third technical problem to be solved by the present invention is to provide a steam emission device with low cost compared to the prior art.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problem is as follows: a steam emission device for installation on the exhaust port on the side wall of the inner cavity of a steam oven. The steam emission device has a steam inlet end and a steam emission end. The steam inlet end is connected to the exhaust port. The steam emission device includes an airflow acceleration component. An air inlet is provided between the airflow acceleration component and the steam inlet end. The airflow acceleration component introduces cold air from the outside through the air inlet.

[0009] In this solution, an air inlet is provided between the airflow acceleration component and the steam inlet. The airflow acceleration component introduces cold air from the outside through the air inlet, which can reduce the temperature of the steam that is finally discharged into the kitchen. This prevents users from being scalded by high-temperature steam and also avoids a humid and hot kitchen environment, thus improving the user experience.

[0010] In the above technical solution, the airflow acceleration component is further provided with a contraction section, a mixing section, and an expansion section in sequence along the gas flow direction. By setting the airflow acceleration component in the form of an ejector tube, the steam gas flow will generate negative pressure when passing through the airflow acceleration component, thereby introducing cold air through the air inlet. In the airflow acceleration component, the high-temperature steam and cold air are fully mixed, reducing the temperature of the steam. The steam cooling can be completed without the need for an additional power device (such as a fan).

[0011] Preferably, the airflow acceleration assembly includes a first airflow acceleration assembly and a second airflow acceleration assembly arranged sequentially at intervals along the airflow direction, with the air inlet located between the first and second airflow acceleration assemblies. By providing two airflow acceleration assemblies, the first airflow acceleration assembly throttles and depressurizes the high-temperature steam, and then the steam passes through the second airflow acceleration assembly, creating a stronger negative pressure zone. This allows the second airflow acceleration assembly to draw in more cold air through the air inlet, resulting in a better cooling effect on the steam.

[0012] Preferably, the central axis of the first airflow acceleration component is parallel to and does not coincide with the central axis of the second airflow acceleration component. By setting the two airflow acceleration components to be non-coaxial, the direction of airflow can be forcibly changed, resulting in better mixing of cold air and steam, while also reducing noise and improving the user experience.

[0013] Preferably, the projected distance between the central axes of the first and second airflow acceleration components on a plane perpendicular to the airflow direction is defined as the misalignment amount δ. A second throat is formed at the junction of the contraction and mixing sections of the second airflow acceleration component, and the diameter of the second throat of the second airflow acceleration component is d2. Then, 0.1d2≤δ≤0.4d2. In this scheme, when δ<0.1d2, the misalignment effect is not obvious, the airflow still passes through approximately in a straight line, and the noise reduction effect is poor. When δ>0.4d2, the airflow resistance increases sharply, and vortices are easily generated in the misalignment dead angle, resulting in poor exhaust. When 0.1d2≤δ≤0.4d2, the misalignment amount of the first and second airflow acceleration devices is appropriate, and no large resistance is generated, achieving the best noise reduction effect and better mixing effect of cold air and steam.

[0014] Preferably, a first throat is formed at the junction of the contraction section and the mixing section of the first airflow acceleration component. The diameter of the channel at the steam inlet end is D, the diameter of the first throat of the first airflow acceleration component is d1, and the diameter of the second throat of the second airflow acceleration component is d2, where d2 < d1 < D. Along the airflow direction, the diameter of the airflow channel decreases sequentially, causing the steam to accelerate gradually and generating negative pressure.

[0015] Preferably, β1 is the first-stage contraction ratio, β2 is the second-stage contraction ratio, β1=d1 / D, β2=d2 / D, β1>β2. If β2≥β1, the second airflow acceleration component cannot generate additional negative pressure, and the air inlet may even exhibit reverse airflow, causing the entire steam emission device to fail. Therefore, β1>β2 must be satisfied.

[0016] Preferably, 0.5≤β1≤0.7 and 0.3≤β2≤0.5. When β1<0.5, the throat of the first airflow acceleration component is too narrow, causing a sharp increase in exhaust back pressure and poor exhaust from the inner liner. When β1>0.7, the throttling effect is weak. When 0.5≤β1≤0.7, a balance is struck between sufficient throttling and acceptable back pressure. When β2<0.3, the throat of the second airflow acceleration component is too narrow, resulting in excessively high back pressure, easy blockage, and high-frequency whistling. When β2>0.5, the suction negative pressure is insufficient, and the cooling effect is significantly reduced. When 0.3≤β2≤0.5, sufficient negative pressure is generated when the airflow passes through without producing noise.

[0017] Preferably, the axial length of the first airflow acceleration component is L1, the axial length of the second airflow acceleration component is L2, and the axial distance from the end face of the expansion section of the first airflow acceleration component to the end face of the contraction section of the second airflow acceleration component is L3, then L2 > L1 > L3. In this scheme, the axial length L1 of the first airflow acceleration component is relatively short, which is used to quickly and initially accelerate the steam and reduce energy loss; L3 is extremely small to maintain the kinetic energy of the high-speed jet and generate strong negative pressure; the axial length of the second airflow acceleration component is the longest, L2, which provides a sufficient mixing and heat exchange path for the hot and cold air, ensuring a significant reduction in exhaust temperature.

[0018] Preferably, 2L1≤L2≤3.5L1. When L2<2L1, the hot and cold air are not mixed sufficiently and the expected cooling effect cannot be achieved. When L2>3.5L1, the second airflow acceleration component is too long, which will increase the flow resistance of the airflow and cause the exhaust to be unsmooth. At the same time, it will cause the overall length of the steam exhaust device to be too long, exceeding the installation space of the side wall of the steam oven.

[0019] Preferably, the diameter of the first throat of the first airflow acceleration component is d1, and the axial distance from the end face of the expansion section of the first airflow acceleration component to the end face of the contraction section of the second airflow acceleration component is L3. Then, 0.5d1≤L3≤1.5d1. For a two-stage airflow acceleration component, in order to ensure that a certain negative pressure is maintained at the inlet of the second airflow acceleration component to facilitate the second-stage acceleration, 0.5d1≤L3≤1.5d1 covers the range from strong negative pressure retention to equilibrium.

[0020] Preferably, the contraction angle of the contraction section of the first airflow acceleration component is θ1, where 15° ≤ θ1 ≤ 25°, and θ1 is the angle between the generatrix of the contraction section and the central axis of the first airflow acceleration component. When θ1 < 15°, the contraction section is too long, increasing frictional losses; when θ1 > 25°, the angle is too large, causing boundary layer separation, resulting in eddies and energy losses. A contraction angle of 15° to 25° allows for the shortest possible contraction section length while ensuring smooth airflow acceleration.

[0021] Preferably, the expansion angle of the expansion section of the second airflow acceleration component is θ2, where 6°≤θ2≤15°, and θ2 is the angle between the generatrix of the expansion section and the central axis of the second airflow acceleration component. The diffusion section is in an adverse pressure gradient environment, where the risk of boundary layer separation is much higher than in the contraction section. When θ2 < 6°, the diffusion section is too long, increasing frictional losses; when θ2 > 15°, significant boundary layer separation occurs, pressure recovery efficiency drops sharply, and turbulent noise may be generated.

[0022] Compared with the prior art, the advantages of this invention are as follows: This application provides a steam emission device for installation on the exhaust port of the inner wall of a steam oven. The steam emission device has a steam inlet end and a steam emission end, the steam inlet end being connected to the exhaust port. The steam emission device includes an airflow acceleration component, and at least one air inlet is provided on the side wall of the steam emission device. The air inlet is located upstream of the airflow acceleration component along the airflow direction, and the airflow acceleration component introduces outside cold air through the air inlet. Compared with the prior art, this invention can passively induce a large amount of cold air to cool the steam, preventing the kitchen environment from becoming humid and hot, thus avoiding damage to cabinets. It also reduces noise, improves the user experience, and eliminates the need for an additional fan, resulting in a simple and compact structure and reduced costs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the steam oven according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of a steam oven equipped with a steam exhaust device according to Embodiment 1 of the present invention; Figure 3 This is a three-dimensional schematic diagram of the airflow acceleration component according to Embodiment 1 of the present invention; Figure 4 This is a three-dimensional schematic diagram of the airflow acceleration component in one orientation according to Embodiment 2 of the present invention; Figure 5 This is a three-dimensional schematic diagram of the airflow acceleration component in Embodiment 2 of the present invention from another orientation; Figure 6 This is a cross-sectional view of the airflow acceleration component of Embodiment 2 of the present invention with angular markings; Figure 7 This is a cross-sectional view of the airflow acceleration component of Embodiment 2 of the present invention, with dimension markings.

[0025] Label Explanation: 1. Steam oven; 11. Vent; 2. Airflow acceleration assembly; 21. First airflow acceleration assembly; 211. First throat; 22. Second airflow acceleration assembly; 221. Second throat; 23. Steam inlet end; 24. Steam outlet end; 25. Air inlet; 26. Contraction section; 27. Mixing section; 28. Expansion section. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to has a specific orientation, or is constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted.

[0031] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] The following is combined Figures 1 to 7The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] Example 1: This invention discloses a steam emission device, with reference to... Figure 1 and Figure 2 As shown, the steam venting device is installed on the exhaust port 11 on the side wall of the inner cavity of the steam oven 1. Figure 4 As shown, the steam emission device has a steam inlet end 23 and a steam outlet end 24. The steam inlet end 23 is connected to the exhaust port 11. The steam generated by the steam oven 1 passes through the exhaust port 11 and is then discharged to the outside through the steam emission device. The steam emission device includes an airflow acceleration component 2. An air inlet 25 is provided between the airflow acceleration component 2 and the steam inlet end 23. The airflow acceleration component 2 introduces outside cold air through the air inlet 25. By providing an air inlet 25 between the steam inlet end 23 and the airflow acceleration component 2, when high-temperature steam flows through the airflow acceleration component 2, a negative pressure is generated in the area where the air inlet 25 is located, thereby drawing outside cold air into the airflow acceleration component 2. Then, the cold air and steam are fully mixed, and the steam temperature is reduced through heat exchange. Finally, the temperature of the steam discharged into the kitchen is reduced, thereby preventing users from being scalded by high-temperature steam and avoiding a humid and hot kitchen environment, improving the user experience. Moreover, this invention can cool the steam without the need for an additional power device (such as a fan).

[0034] In this embodiment, refer to Figure 3 As shown, the airflow acceleration assembly 2 is sequentially arranged with a contraction section 26, a mixing section 27, and an expansion section 28 along the gas flow direction. By setting the airflow acceleration assembly 2 in the form of an ejector, the steam gas flow passes through the airflow acceleration assembly 2. The ejector has a Venturi tube structure, and its inherent characteristics generate negative pressure when the steam flows through it. The ejector structure is simple and easy to manufacture, requiring no additional structures or significant modifications to the steam exhaust device. Cold air can be introduced through the air inlet 25, and then the steam and cold air can be fully mixed in the mixing section to reduce the steam temperature. No additional power device (such as a fan) is needed to cool the steam. In addition to the ejector, the airflow acceleration assembly 2 also includes other components that can generate negative pressure according to Bernoulli's principle.

[0035] Example 2: In this embodiment, refer to Figure 4 and Figure 5As shown, the airflow acceleration component 2 includes a first airflow acceleration component 21 and a second airflow acceleration component 22 arranged sequentially at intervals along the airflow direction, with the air inlet 25 located between the first airflow acceleration component 21 and the second airflow acceleration component 22. When steam is discharged from the exhaust port 11 of the steam oven 1, the cross-sectional area of ​​the channel suddenly decreases after passing through the first airflow acceleration component 21, and the steam is accelerated for the first time. Then, it is accelerated a second time after passing through the second airflow acceleration component 22. According to Bernoulli's principle, the faster the flow rate, the greater the negative pressure generated. Therefore, a strong negative pressure zone is generated, which allows more cold air to be drawn through the air inlet 25, resulting in a better cooling effect for the steam.

[0036] In this embodiment, refer to Figure 4 As shown, the central axis of the first airflow acceleration component 21 is parallel to and does not coincide with the central axis of the second airflow acceleration component 22. This non-coaxial design forces the high-temperature steam to change direction after exiting the first airflow acceleration component 21, and the high-speed jet is no longer directly facing the axis of the second airflow acceleration component 22. It first impacts the inlet edge or sidewall of the constriction section of the second airflow acceleration component 22. This collision breaks up large-scale airflow into small-scale and unorganized airflow particles, creating turbulent flow. Hot and cold air are forcibly mixed together, resulting in intense mixing and effectively reducing the exhaust temperature. Simultaneously, the spatial offset avoids interfering with the initial throttling effect of the first airflow acceleration component 21. If the two airflow acceleration components were arranged coaxially, the steam would directly rush at high speed towards the rear of the second airflow acceleration component 22. The negative pressure generated at the inlet 25 would be weak, resulting in a limited amount of cold air intake and poor cooling effect. This straight-through steam flow would form a "core high-speed zone," where cold air only mixes around it, resulting in insufficient heat exchange and a still high exhaust gas temperature. In a coaxial design, high-speed steam flows out from the first airflow acceleration component 21, forming an axisymmetric concentrated core jet, which produces a sharp and piercing noise. In a non-coaxial design, by forcibly changing the airflow direction, the airflow impacts the side wall of the steam emission device, dispersing the concentrated energy into small-scale turbulence, transforming the sharp whistling sound into a soft, broadband airflow noise, thereby reducing the noise.

[0037] In this embodiment, refer to Figure 4 and Figure 6As shown, the projection distance between the central axis of the first airflow acceleration component 21 and the central axis of the second airflow acceleration component 22 on a plane perpendicular to the airflow direction is defined as the misalignment amount δ. The second throat 221 is formed at the junction of the contraction section and the mixing section of the second airflow acceleration component 22. The diameter of the second throat 221 of the second airflow acceleration component 22 is d2, then 0.1d2≤δ≤0.4d2. When δ<0.1d2, the misalignment effect is not obvious, and steam flows out from the first airflow acceleration component 21, forming a symmetrical and concentrated core jet. When this airflow enters the second airflow acceleration component 22, it will produce a whistling sound; moreover, the steam will directly rush to the rear of the second airflow acceleration component 22, and the negative pressure generated at the air inlet 25 is weak, resulting in insufficient intake of cold air and insufficient mixing of cold air and steam, so that the steam temperature hardly decreases. When δ > 0.4d², the airflow resistance increases sharply, easily generating vortices in the misalignment dead angle, leading to poor exhaust. When 0.1d² ≤ δ ≤ 0.4d², the first airflow acceleration component 21 and the second airflow acceleration component 22 form a suitable misalignment. After the airflow exits from the first airflow acceleration component 21, it impacts the wall of the second airflow acceleration component 22, causing the concentrated airflow to be dispersed, resulting in the mixing of cold air and hot steam. The dispersed airflow prevents whistling sounds, avoids the formation of misalignment dead angles, and ensures unobstructed exhaust.

[0038] In one specific embodiment, δ is set to 0.35d², which is suitable for a large-capacity steam oven 1 with a large amount of steam and a high temperature, making it suitable for cooking equipment scenarios that require rapid cooling. In another embodiment, δ is set to 0.15d², which is suitable for a small-capacity steam oven 1. When entering the second airflow acceleration component 22, the small misalignment can slightly change the direction of the airflow, avoiding concentrated jets, and since the amount of steam is small, a small amount of cold air is sufficient to lower its temperature.

[0039] In this embodiment, refer to Figure 6 As shown, a first throat 211 is formed at the junction of the contraction section and the mixing section of the first airflow acceleration component 21. The channel diameter of the steam inlet end 23 is D, the diameter of the first throat 211 of the first airflow acceleration component 21 is d1, and the diameter of the second throat 221 of the second airflow acceleration component 22 is d2. Then d2 < d1 < D. Along the airflow direction, the diameter of the airflow channel decreases sequentially. By gradually contracting the channel, the steam is smoothly accelerated to the required high speed, avoiding flow separation and excessive loss caused by a single-stage large contraction ratio, as well as generating a strong jet whistling. At the same time, the finer throat of the second airflow acceleration component 22 is used to generate a strong negative pressure zone locally, driving the intake of external cold air, and the longer second airflow acceleration component 22 completes full mixing and heat exchange.

[0040] In this embodiment, refer to Figure 6As shown, β1 is the first-stage contraction ratio, β2 is the second-stage contraction ratio, β1=d1 / D, β2=d2 / D, β1>β2. If β2≥β1, it means that the diameter of the second airflow acceleration component 22 is larger than the diameter of the first airflow acceleration component 21. After the airflow comes out of the first airflow acceleration component 21, it enters the second airflow acceleration component 22 with a larger diameter. The airflow will not be accelerated. Therefore, the second airflow acceleration component 22 cannot generate additional negative pressure. The air inlet 25 may even have reverse airflow, causing the entire steam emission device to fail. Therefore, β1>β2 must be satisfied.

[0041] In this embodiment, refer to Figure 6 As shown, 0.5≤β1≤0.7, 0.3≤β2≤0.5. When β1<0.5, the throat of the first airflow acceleration component 21 is too narrow, the exhaust back pressure rises sharply, the exhaust from the inner liner is not smooth, and the steam cannot be discharged smoothly, affecting the normal operation of the steamer. When β1>0.7, the effect on increasing the airflow velocity is limited, and an effective high-speed jet cannot be formed, resulting in a weak throttling effect. Therefore, when 0.5≤β1≤0.7, the airflow can be appropriately accelerated, the back pressure is suitable, and it will not lead to high exhaust resistance. This is a balance range that takes into account both sufficient throttling and acceptable back pressure. Preferably, β1 can be 0.55, 0.6, or 0.65. When β2 < 0.3, the second throat 221 of the second airflow acceleration component 22 is the narrowest cross-section in the entire flow path. The excessively narrow throat of the second airflow acceleration component 22 generates significant back pressure, increasing the airflow exhaust resistance. The pressure in the upstream cavity needs to be sufficiently high to drive steam through such a small aperture. This high pressure is transmitted back to the first airflow acceleration component 21, further obstructing exhaust. Furthermore, the high-speed airflow passing through the small aperture generates a high-frequency whistling sound, increasing noise. When β2 > 0.5, the generated negative pressure is insufficient, resulting in insufficient cold air intake and a significant decrease in cooling effect. Therefore, when 0.3 ≤ β2 ≤ 0.5, the airflow passing through the second airflow acceleration component 22 can generate sufficient negative pressure without generating excessive back pressure or whistling, balancing the negative pressure intensity with resistance and noise. Preferably, β2 can be 0.35 or 0.4.

[0042] In this embodiment, refer to Figure 5As shown, the axial length of the first airflow acceleration component 21 is L1, the axial length of the second airflow acceleration component 22 is L2, and the axial distance from the end face of the expansion section of the first airflow acceleration component 21 to the end face of the contraction section of the second airflow acceleration component 22 is L3. Therefore, L2 > L1 > L3. In this scheme, the axial length L1 of the first airflow acceleration component 21 is relatively short. When the steam is discharged from the exhaust port 11 of the inner liner, the pressure is not high. The first airflow acceleration component 21 is used for initial steam acceleration and does not need to reach the maximum speed. It only needs to provide a stable high-speed airflow for the second airflow acceleration component 22. If the axial length L1 is too long, it will increase the frictional resistance and cause unnecessary energy loss. L3 is the smallest to prevent the high-speed airflow from diffusing in free space and to decelerate it. The axial length of the second airflow acceleration component 22 is the longest, L2. After the cold air is injected from the air inlet 25, the cold air and hot steam can be fully mixed in the second airflow acceleration component 22, the heat exchange is more thorough, the exhaust temperature is significantly reduced, and the long channel allows the airflow to gradually decelerate and the pressure to recover, reducing the noise generated by the sudden expansion during exhaust.

[0043] In this embodiment, refer to Figure 5 As shown, when L2 < 2L1, the residence time of the mixed gas in the second airflow acceleration component 22 is insufficient. The cold air may only mix with the periphery of the steam, resulting in insufficient mixing of hot and cold air. The steam in the core area is discharged before it has cooled down, which will lead to a large difference between the highest and lowest temperatures of the finally discharged airflow, forming local high temperatures and failing to achieve the expected cooling effect. When L2 > 3.5L1, the second airflow acceleration component 22 is too long. The airflow will rub against the wall in the pipe, resulting in pressure loss. The mixing effect is very limited, but the friction loss increases linearly, increasing the flow resistance of the airflow and causing poor exhaust. At the same time, it will cause the overall length of the steam exhaust device to be too long, exceeding the installation space of the side wall of the steam oven 1. Therefore, when 2L1 ≤ L2 ≤ 3.5L1, it is possible to balance efficient cooling and noise reduction in a compact installation space without excessively increasing the flow resistance of the airflow and discharging low-temperature airflow.

[0044] In this embodiment, refer to Figure 5 and Figure 6 As shown, the diameter of the first throat 211 of the first airflow acceleration component 21 is d1, and the axial distance from the end face of the expansion section of the first airflow acceleration component 21 to the end face of the contraction section of the second airflow acceleration component 22 is L3. Therefore, 0.5d1 ≤ L3 ≤ 1.5d1. According to the pressure recovery characteristics of a Venturi tube, the pressure recovery rate decreases exponentially after the airflow passes through the throat. ΔP(x) / ΔPmax=1-ek·x / d1; in: •ΔP(x): Pressure recovery value at a distance x from the throat outlet; •ΔPmax: The maximum pressure value at which full recovery is achieved; •k: empirical coefficient, approximately 0.5~1.0.

[0045] For the two-stage airflow acceleration component 2, in order to ensure that a certain negative pressure is maintained at the inlet of the second airflow acceleration component 22 (i.e., not completely restored) to facilitate the second-stage acceleration, it is generally ideal to maintain a negative pressure of 30% to 50%. Corresponding to the L3 / d1 ratio: when L3 / d1=0.5, the pressure recovers to about 20% to 30%, and the negative pressure is sufficiently maintained; when L3 / d1=1.0, the pressure recovers to about 50% to 60%, which is relatively balanced; when L3 / d1=1.5, the pressure recovers to about 70% to 80%, and the effect of the first stage is weakened; when L3 / d1>2.0, it is basically completely restored, and the first stage becomes meaningless. Therefore, 0.5d1≤L3≤1.5d1 covers the range from strong negative pressure maintenance to balance.

[0046] In this embodiment, refer to Figure 7 As shown, the contraction angle of the contraction section of the first airflow acceleration component 21 is θ1, where 15°≤θ1≤25°, and θ1 is the angle between the generatrix of the contraction section and the central axis of the first airflow acceleration component 21. When θ1<15°, the contraction section is too long, and the airflow travels too far along the contraction section, resulting in increased friction loss and energy loss. When θ1>25°, the angle is too large, and the airflow will not travel along the wall, causing separation between the airflow and the wall, i.e., boundary layer separation begins, generating eddies and energy loss. A contraction angle of 20°~22° can achieve the shortest contraction section length while ensuring smooth airflow acceleration.

[0047] In this embodiment, refer to Figure 7 As shown, the expansion angle of the expansion section of the second airflow acceleration component 22 is θ2, where 8°≤θ2≤12°, and θ2 is the angle between the generatrix of the expansion section and the central axis of the second airflow acceleration component 22. The diffusion section is in an adverse pressure gradient environment, where the risk of boundary layer separation is much higher than in the contraction section. When θ2 < 6°, the diffusion section is too long, increasing frictional losses, and the low outlet velocity can negatively impact exhaust flow. Furthermore, the limited space on the sidewall of the steam oven 1 prevents the installation of an excessively long structure. When θ2 > 15°, when the airflow enters the expansion section, the sudden expansion of the channel causes significant boundary layer separation, resulting in a sharp drop in pressure recovery efficiency. This boundary layer separation also leads to severe distortion of the outlet velocity distribution, with high velocity at the center and low velocity at the edges. This uneven airflow generates turbulent noise when discharged into the kitchen environment. An expansion angle of 8°~12° ensures that the airflow avoids boundary layer separation in an adverse pressure gradient environment while controlling the length of the expansion section to prevent excessive frictional losses.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A steam exhaust device for installation on the exhaust port on the side wall of the inner cavity of a steam oven, the steam exhaust device having a steam inlet end (23) and a steam exhaust end (24), the steam inlet end (23) being connected to the exhaust port (11), characterized in that, The steam emission device includes an airflow acceleration component (2), and an air inlet (25) is provided between the airflow acceleration component (2) and the steam inlet end (23). The airflow acceleration component (2) introduces outside cold air through the air inlet (25).

2. The steam emission device according to claim 1, characterized in that, The airflow acceleration component (2) is provided with a contraction section (26), a mixing section (27) and an expansion section (28) in sequence along the gas flow direction.

3. The steam emission device according to claim 2, characterized in that, The airflow acceleration component (2) includes a first airflow acceleration component (21) and a second airflow acceleration component (22) arranged sequentially at intervals along the airflow direction, and the air inlet (25) is located between the first airflow acceleration component (21) and the second airflow acceleration component (22).

4. The steam emission device according to claim 3, characterized in that, The central axis of the first airflow acceleration component (21) is parallel to and does not coincide with the central axis of the second airflow acceleration component (22).

5. The steam emission device according to claim 4, characterized in that, The projection distance between the central axis of the first airflow acceleration component (21) and the central axis of the second airflow acceleration component (22) on a plane perpendicular to the airflow direction is defined as the misalignment amount δ. A second throat (221) is formed at the junction of the contraction section and the mixing section of the second airflow acceleration component (22). The diameter of the second throat (221) of the second airflow acceleration component (22) is d2, then 0.1d2≤δ≤0.4d2.

6. The steam emission device according to claim 3, characterized in that, A first throat (211) is formed at the junction of the contraction section and the mixing section of the first airflow acceleration component (21). The channel diameter of the steam inlet end (23) is D. The diameter of the first throat (211) of the first airflow acceleration component (21) is d1. The diameter of the second throat (221) of the second airflow acceleration component (22) is d2. Then d2 < d1 < D.

7. The steam emission device according to claim 6, characterized in that, β1 is the first-order shrinkage ratio, β2 is the second-order shrinkage ratio, β1=d1 / D, β2=d2 / D, and β1>β2.

8. The steam emission device according to claim 7, characterized in that, 0.5≤β1≤0.7，0.3≤β2≤0.5。 9. The steam emission device according to claim 3, characterized in that, The axial length of the first airflow acceleration component (21) is L1, the axial length of the second airflow acceleration component (22) is L2, and the axial distance from the end face of the expansion section of the first airflow acceleration component (21) to the end face of the contraction section of the second airflow acceleration component (22) is L3. Then L2 > L1 > L3.

10. The steam emission device according to claim 9, characterized in that, 2L1≤L2≤3.5L1.

11. The steam emission device according to claim 3, characterized in that, The diameter of the first throat (211) of the first airflow acceleration component (21) is d1, and the axial distance from the end face of the expansion section of the first airflow acceleration component (21) to the end face of the contraction section of the second airflow acceleration component (22) is L3. Then 0.5d1≤L3≤1.5d1.

12. The steam emission device according to claim 3, characterized in that, The contraction angle of the contraction section of the first airflow acceleration component (21) is θ1, 15°≤θ1≤25°, where θ1 is the angle between the generatrix of the contraction section and the central axis of the first airflow acceleration component (21).

13. The steam emission device according to claim 3, characterized in that, The expansion angle of the expansion section of the second airflow acceleration component (22) is θ2, 6°≤θ2≤15°, where θ2 is the angle between the generatrix of the expansion section and the central axis of the second airflow acceleration component (22).

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