Uncoated non-stick inner pot and uncoated electric rice cooker

Abstract

Disclosed in the present application are an uncoated non-stick inner pot and an uncoated electric rice cooker. The uncoated non-stick inner pot comprises a stainless steel inner pot formed by means of sheet metal stretching. A surface of an inner stainless steel substrate of the stainless steel inner pot is subjected to laser shock to form a micron-level texture. The micron-level texture comprises ridges and grooves, wherein the ridges and the grooves are randomly distributed on the surface of the substrate, and the height differences between the ridges and the grooves randomly fluctuate within 20 μm. The present application changes the contact mode of droplets on a rough surface of stainless steel, making it difficult for starch liquid to spread on the surface of the stainless steel substrate. Therefore, formed starch paste is in a non-uniform state, thereby enhancing the non-stick property.

Description

A non-coating non-stick inner pot and a non-coating rice cooker

[0001] This application claims priority to the following Chinese patent applications, the entire contents of which are incorporated herein by reference:

[0002] A Chinese patent application with application number 202410293223.5, titled “A 0-coating non-stick inner pot and a 0-coating rice cooker,” was submitted to the China Patent Office on March 14, 2024;

[0003] A Chinese patent application with application number 202410293233.9, titled “A 0-coating non-stick inner pot and a 0-coating rice cooker,” was submitted to the China Patent Office on March 14, 2024;

[0004] A Chinese patent application with application number 202420497321.6, titled “An Air-Cooled 0-Coating Non-Stick Rice Cooker,” was submitted to the China Patent Office on March 14, 2024;

[0005] A Chinese patent application with application number 202420497327.3, titled “A 0-coating non-stick inner pot and a 0-coating rice cooker,” filed with the China Patent Office on March 14, 2024; and

[0006] A Chinese patent application was submitted to the China Patent Office on March 14, 2024, with application number 202420504453.7 and invention name "A 0-coating rice cooking utensil and a 0-coating rice cooker". Technical Field

[0007] The present application belongs to the technical field of kitchen appliances, and in particular relates to an uncoated non-stick inner pot and an uncoated rice cooker. Background Art

[0008] Rice cookers can stick to the pot during cooking, making them difficult to clean after meals and degrading the user experience. To prevent rice from sticking, conventional rice cookers typically use a non-stick coating on the inner wall. However, this coating is prone to detachment during long-term cooking, especially during high-temperature cooking and dry cooking. This not only affects the anti-sticking effect but also poses a certain risk to human health.

[0009] As users have an increasing demand for healthy cooking, cooking utensils without coatings are gaining more and more attention. Using a hydrophobic surface to directly contact food is one of the important research directions. Currently, there are the following schemes for obtaining a hydrophobic surface: one is a non-stick pan as disclosed in patent CN116439565A, which forms an orderly arranged papillary structure on the inner surface of the pan body by laser etching. The papillary structure includes a first protrusion distributed in an array on the inner surface of the pan body and a second protrusion evenly distributed on the first protrusion; the other is a homogeneous hemispherical metallurgically bonded non-stick pan as disclosed in patent CN216628245U, which uses an additive method opposite to the previous one, and forms a hemispherical layer with a number of small spheres on the inner surface of the pan body by eutectic metallurgical bonding of the particles with the pan body.

[0010] However, rice cooking utensils such as rice cooker liners or pressure cooker liners are different from the above-mentioned non-stick pans. The amount of rice cooked is generally large and the rice grains will absorb water and expand. When the structure of the above-mentioned non-stick pan is applied to the surface of the rice cooking utensil, the side with less heat is prone to excessive gelatinization of the rice due to excessive water and steam, while the bottom with more heat is prone to burnt and clumping of rice due to less water and steam, thereby affecting the overall non-stick effect and cooking uniformity.

[0011] Summary of the Invention

[0012] The present application provides an uncoated non-stick inner pot and an uncoated rice cooker to improve the non-stick effect of the uncoated inner pot.

[0013] On the one hand, the technical solution adopted in one embodiment of the present application is:

[0014] A non-stick, uncoated liner comprises a stainless steel liner formed by stretching a plate, wherein the inner stainless steel substrate surface of the stainless steel liner is subjected to laser shock to form a micron-scale textured pattern, wherein the micron-scale textured pattern comprises ridges and grooves, wherein the ridges and grooves are randomly distributed on the substrate surface, and the height difference between the ridges and grooves fluctuates randomly within 20 μm.

[0015] On the other hand, another embodiment of the present application proposes an uncoated electric rice cooker, comprising a cooker body, the cooker body being provided with a cooling fan and a accommodating cavity for accommodating any of the uncoated non-stick inner pots described above, the cooker body being provided with a cooker lid, the cooling fan being used to introduce cooling airflow into the accommodating cavity, and an airflow outlet being provided between the cooker lid and the cooker body, wherein the airflow outlet located on the rear side of the cooker body is larger than the airflow outlet on the front side.

[0016] Due to the adoption of the above technical solution, the beneficial effects achieved by this application are as follows:

[0017] When laser impact treatment forms a micron-scale textured surface on the stainless steel substrate, the roughness increases, but the resulting hydrophobicity increases. This indicates that the current wetting mode is no longer a single Wenzel model, but at least a composite contact mode composed of Wenzel and Cassic. Further analysis shows that laser impact treatment can produce randomly distributed ridges and grooves on the stainless steel substrate surface. The height difference of these ridges and grooves fluctuates randomly within 20 μm, thus forming ridges and grooves of different sizes, ranging from 10-20 microns, 1-10 microns, and even hundreds of nanometers. This changes the contact mode of the droplet on the rough stainless steel surface, making it difficult for the starch solution to spread on the stainless steel substrate. As a result, the formed starch paste is in an uneven state, improving its non-stickiness. In addition, the random distribution can increase the heating area of ​​the rice, making it easier to form a staggered heat flow at the bottom, thereby stirring the rice and ensuring that it is fully heated, thereby improving the cooking effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0019] FIG1 is a cross-sectional view of a cooking utensil provided in an embodiment of the present application;

[0020] FIG2 is a cross-sectional view of the inner container structure provided in an embodiment of the present application;

[0021] FIG3 is a schematic diagram of a bite pattern provided in an embodiment of the present application;

[0022] FIG4 is a diagram of a 3D morphological thermal model established based on FIG3 ;

[0023] FIG5 is a schematic diagram showing the outline of ridges and grooves along a straight line selected from FIG3;

[0024] FIG6 is a partial enlarged schematic diagram of point A in FIG4 ;

[0025] FIG7 is a schematic diagram of the front and rear sides of the airflow outlet according to an embodiment of the present application;

[0026] FIG8 is a schematic diagram of a cooling fan in an embodiment of the present application.

[0027] The reference numerals in Figures 1 to 8 are: pot body 10; cooling fan 101; accommodating cavity 102; airflow outlet 103, flared portion 104, heating device 105; pot lid 20; inner pot 30; bottom wall 31; side wall 32; cooking cavity 33; ridge 300; groove 400; peaks 301, 302; ridge body 303; depression 304, main vein 305; branch vein 306.

[0028] FIG9 is a schematic structural diagram of the uncoated non-stick liner according to one embodiment of the present application;

[0029] FIG10 is a schematic structural diagram of the uncoated non-stick liner according to one embodiment of the present application;

[0030] FIG11 is a schematic diagram of the local morphology of the micron-scale biting pattern according to one embodiment of the present application;

[0031] FIG12 is a schematic diagram of the local morphology of the micron-scale biting pattern according to one embodiment of the present application;

[0032] FIG13 is a schematic diagram of the state of rice grains according to one embodiment of the present application;

[0033] FIG14 is a schematic structural diagram of the uncoated rice cooker according to one embodiment of the present application;

[0034] Figure 15 is a structural schematic diagram of the uncoated rice cooker under one embodiment of the present application.

[0035] The reference numerals in Figures 9 to 15 are: stainless steel metal layer 100; micron-level bite pattern 106; water layer 107; rice grains 108; ridges 109; grooves 110; bottom wall 111 of the pot body; inner wall 120 of the pot body; upper part 121 of the inner wall of the pot body; middle part 122 of the inner wall of the pot body; lower part 123 of the inner wall of the pot body; flange 200; pot body 3001; fan assembly 3010; accommodating cavity 3020; pot lid 4001; air outlet 5001; air outlet gap 6001.

[0036] FIG16 is a cross-sectional view of a rice cooker according to an embodiment of the present application;

[0037] FIG17 is a schematic diagram of the rice cooker with the lid opened according to the embodiment of the present application;

[0038] FIG18 is a rear view of the rice cooker according to the embodiment of the present application.

[0039] 16 to 18 are denoted by the following reference numerals: inner pot 1 , pot body 2 , pot cover 3 , flared portion 4 , cooling fan 5 , and convex portion 6 . DETAILED DESCRIPTION

[0040] In order to more clearly illustrate the overall concept of the present application, a detailed description is given below in an illustrative manner in conjunction with the accompanying drawings.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0042] In addition, in the description of the present application, it should be understood that the terms "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present application.

[0043] In this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0044] In this application, unless otherwise expressly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0045] Most existing rice cooker pots are coated, that is, a Teflon coating (scientific name polytetrafluoroethylene, abbreviated as PTFE) is provided on the inner surface of the pot. The uncoated pot of the present application is different from the above-mentioned coated pot. The coating is no longer provided on the base material of the pot, so the inner side wall of the pot is a metal layer that can come into contact with food. The metal layer can be stainless steel. When cooking, food is directly contacted and cooked through the metal layer of the pot, thereby eliminating the coating shedding of the coated pot and the dietary health problems caused by the coating itself.

[0046] When cooking rice, the existing rice cooker inner pot is mainly heated by a heating device arranged on the bottom side of the inner pot. The heat is mainly concentrated on the bottom wall. After the rice is cooked, the moisture is absorbed by the rice, resulting in a decrease in the residual liquid between the inner pot and the rice, increasing the risk of sticking to the pot.

[0047] The main component of rice is starch, which mainly exists in rice in the form of starch granules. Under the action of heat and moisture, it can undergo gelatinization. During this period, some starch precipitates from the starch granules. After gelatinization, it forms a starch liquid with high viscosity with water. When there is sufficient water, the starch liquid can flow freely between the gaps in the rice in the inner pot and reach the interface between the inner pot and the rice.

[0048] The contact angle of ordinary stainless steel is less than 90 degrees, close to 80 degrees, so its wettability is closer to hydrophilicity; this is because the surface of stainless steel is mainly an oxide layer, which is a non-polar film layer, so it is not easily wetted by water, but its surface energy is relatively high, so it exhibits strong hydrophilicity.

[0049] Research has shown that there are two main modes of solid-liquid wetting on rough surfaces: Wenzel and Cassic. In the Wenzel wetting mode, the liquid always fills the groove structure on the surface, while in the Cassic wetting mode, the liquid droplets do not fill the grooves on the rough surface, and there is trapped air under the liquid droplets in the grooves. The contact angle of an ordinary stainless steel surface is around 80 degrees. If the wetting mode is the Wenzel mode, for a rough surface with a contact angle less than 90 degrees, the roughness increases, the contact angle decreases, and the hydrophilicity increases, so the starch liquid can spread more easily on the surface of the stainless steel substrate. If the starch liquid fully infiltrates the surface of the inner tank, when there is insufficient water at the interface, it will be conducive to the formation of a uniform starch paste, so that the starch paste is fully bonded to the metal tank wall, thereby causing a serious bonding problem. If the rough surface can achieve the Cassic mode, the hydrophilic interface will also have a larger contact angle and the hydrophobicity will increase, making it even more difficult for the starch liquid to spread on the stainless steel surface.

[0050] The present application proposes a rice cooking utensil, which may be an electric rice cooker or a pressure cooker. In some other embodiments, the rice cooking utensil may be other cooking utensil with rice cooking function.

[0051] Referring to FIG1 , an electric rice cooker is shown. The electric rice cooker comprises a body 10, a lid 20, and an inner pot 30. The inner pot 30 is disposed within the body 10, with the inner side of the inner pot 30 in contact with the rice via a metal layer. The lid 20 covers the body 10, and the body 10 is provided with a heating device 105 for heating the inner pot 30. During cooking, a rice-water mixture is added to a cooking cavity 33 within the inner pot 30, and the rice is cooked under the heating of the heating device 105 at the bottom of the inner pot 30. FIG2 shows the inner pot 30 of the electric rice cooker of FIG1 , which includes a bottom wall 31 and side walls 32.

[0052] In a specific embodiment of the present application, the cooking utensil is used to cook rice using an uncoated or zero-coated inner pot.

[0053] The present application proposes an uncoated non-stick liner, comprising a stainless steel liner formed by stretching a plate, as shown in FIG3 , the inner stainless steel substrate surface of the stainless steel liner (i.e., the inner surface of the liner) is laser-shocked to form a micron-level texture, as shown in FIG4 , the micron-level texture comprises a plurality of ridges 300 and a plurality of grooves 400, the ridges 300 and the grooves 400 being randomly distributed on the surface of the substrate, and the height difference between the ridges and the grooves is randomly fluctuating within 20 μm.

[0054] Figure 3 shows a micron-scale micrograph of the bite pattern obtained using a Keyence VHX-7000N digital microscope. Figure 4 shows a 3D thermal model of the morphology constructed using the XYZ spatial rectangular coordinate system based on the micrograph in Figure 3. Color contrast in the Z direction distinguishes the height difference of the bite pattern. The color contrast on the left indicates the height of the morphology, increasing in value from bottom to top. The black area in the figure represents the relatively concave portion, and the white area represents the relatively convex portion. Figure 5 shows a schematic diagram of the outline of the ridges and grooves along a straight line selected from Figure 3, showing the height difference at reference point 1 of 3.04μm, the height difference at reference point 2 of 1.96μm, and the height difference at reference point 3 of 1.91μm. The height difference here refers to the distance from the top of the ridge to the bottom of the groove.

[0055] Experiments have found that when the surface of the stainless steel substrate is laser-impacted to form a micron-scale bite pattern, the roughness increases, but the result is that the hydrophobicity increases, indicating that the current wetting mode is no longer a single Wenzel model, but at least a composite contact mode composed of Wenzel and Cassic. Further analysis shows that laser shock can process randomly distributed ridges and grooves on the surface of the stainless steel substrate, and the height difference of the ridges and grooves randomly fluctuates within 20um, thereby forming ridges and grooves of different size levels, with fluctuation heights ranging from 10-20 microns, 1-10 microns, and hundreds of nanometers. This changes the contact mode of the droplet on the rough surface of the stainless steel, making it difficult for the starch solution to spread on the surface of the stainless steel substrate. For this reason, the formed starch paste is in an uneven state, which improves the non-stickiness.

[0056] First, if the size of the substrate surface is not rich enough and is relatively uniform, the interface will be fully infiltrated, so that the amount of starch paste subsequently formed at each interface will be consistent; second, if the protrusions of the same size are distributed regularly, it will be easier to form a uniformly distributed starch paste, which will easily cause the rice to bond with the wall of the pan, causing the rice to stick to the pan easily.

[0057] To further improve the contact state of the subsequent starch paste at the interface, a micron-scale bite pattern with a random undulation of 20μm height differences is designed to interlock with the starch paste. This interlocking pattern, in areas of concentrated heat, tends to generate intense steam, making the starch paste formed at the interface due to insufficient moisture later appear porous rather than a uniform film. This porous structure facilitates the release of rice from the liner, reducing residue. Furthermore, the random distribution increases the heating surface area of ​​the rice, making it easier to form a staggered heat flow at the bottom, thereby stirring the rice and ensuring it is fully heated, thereby improving the cooking effect.

[0058] In some specific embodiments of the present application, the substrate surface includes an inner wall surface and a bottom surface, at least a portion of the ridges and at least a portion of the grooves are located on the inner wall surface, and the height difference between the ridges and grooves on the inner wall surface randomly fluctuates within 15 μm. Because the ridges and grooves on the inner wall surface are located on the side, the side bite pattern easily engages with the starch paste of the rice, and the deeper grooves easily hinder the rice from escaping along the depth direction of the inner pot. Therefore, setting the height difference relatively small means that the inner wall surface is smoother, thereby ensuring that deep grooves do not appear on the inner pot side wall, reducing the bite force between the rice and the inner pot side wall, and facilitating the rice to fall out of the inner pot.

[0059] In some specific embodiments of the present application, the substrate surface includes an inner wall surface and a bottom surface, a portion of the ridges and a portion of the grooves are located on the inner wall surface, another portion of the ridges and another portion of the grooves are located on the bottom surface, and the maximum height difference between the ridges and grooves on the bottom surface is greater than the corresponding value on the inner wall surface. That is, the maximum height difference between the ridges and grooves on the bottom surface is greater than the maximum height difference between the ridges and grooves on the inner wall surface. The bottom surface is near a heat source and is prone to steam generation, making it difficult for the starch paste to interlock with the grooves and ridges, even if the bottom surface has a large height difference. A large height difference means a greater modification of the stainless steel surface, resulting in a richer morphology on the stainless steel surface, which in turn facilitates the formation of a Cassic infiltration pattern.

[0060] The specific implementation of this application proposes the following three 3L stainless steel liner samples, stainless steel liner sample 1# and stainless steel liner sample 2# as the control group, and stainless steel liner sample 3# as the experimental group:

[0061] Stainless steel liner sample 1#: 316L stainless steel, the substrate surface has no obvious ridges and grooves, and is a relatively smooth plane;

[0062] Stainless steel liner sample 2#: 316L stainless steel, the substrate surface is provided with an array of circular grooves with a spacing of 0.8 mm and a diameter of 0.6 mm;

[0063] Stainless steel liner sample 3#: 316L stainless steel, ridges and grooves are randomly distributed on the surface of the substrate, and the height difference between the ridges and grooves is randomly fluctuated within 20 μm.

[0064] The experimental results are shown in the following table.

[0065] Judging from the above experimental results, the contact angle of sample 3# becomes larger, the residue amount decreases, the rice and the inner pot are easier to separate, and the non-stick effect becomes better.

[0066] In a specific embodiment of the present application, as shown in FIG6 , which is a partial enlarged view of point A in FIG4 , the ridge includes a ridge body 303 and peaks (301, 302), the peaks being located on the top side of the ridge body, and the surface of the ridge body 303 and the surface of the peaks forming a facet, the facet extending from the peaks to one side of the gully, the gully 400 being bounded by the facet, and the directions of different ridge bodies 303 on the surface of the substrate are different.

[0067] The ridge body and the peak are both part of the stainless steel substrate. From a microscopic point of view, the ridge face is part of the surface of the substrate.

[0068] As shown in Figures 4 and 6, the ridge has a certain shape. For the convenience of description, the spatial rectangular coordinate system XYZ is used for description. It is assumed that the thickness direction of the substrate is the Z direction, and the substrate surface has a length direction X and a width direction Y. Therefore, when looking down from the Z direction to the plane formed by XY, the shape of the ridge is mainly determined by the ridge body. The height difference of the ridge along the Z direction can be determined by the peak, and the morphology below the height range of the peak is determined by the ridge body.

[0069] It should be understood that the peak can be a part of the ridge rather than just the highest point, that is, it can have a certain shape and a certain size range, and the peaks of different ridges may also be different. Generally speaking, the peak can be the one that can characterize the maximum height of the current ridge body.

[0070] It should be understood that the points on the facet need to be characterized in the three directions of X, Y, and Z, which means that the facet extends in height, length, and width, so the shape of the facet is relatively complex; generally speaking, the facet converges upward along the Z direction at the peak and extends downward to the lowest point of the ravine.

[0071] The gully has no entity and belongs to the spatial part. Its boundary is the aforementioned facet, and its shape is naturally formed by the facets.

[0072] The randomly distributed ridges and grooves have randomness reflected in the ridge faces, ridge bodies and peaks. Specifically, for the ridge bodies, different directions on the XY plane result in different directions of the grooves. On the surface of the substrate, different ridge bodies have different directions on the substrate surface, resulting in different directions of the grooves, and thus the substrate surface has many grooves with different directions.

[0073] During high-temperature cooking, when there is sufficient water, the gullies in the Wenzel mode will store starch liquid. Due to sufficient water, the rice will not stick to the pan at this time. However, at the end of cooking, most of the water in the inner pot has evaporated and been absorbed by the rice itself, resulting in insufficient water in the inner pot. At this time, the starch liquid is in a paste-like state, and the viscosity of the paste-like starch liquid becomes higher, the fluidity is poor, and it is easy to stick to the pan. However, since the heat dissipation and thermal conductivity of the stainless steel substrate are better than those of rice, at the end of cooking, the heat at the interface between the rice and the stainless steel substrate is easily dissipated, causing the high-temperature water vapor in the rice to easily form condensed water at the interface, resulting in a relative increase in the water content at the interface, thereby increasing the fluidity at the interface. When the starch liquid in the gullies is cooled, the dissolved starch in it is easily precipitated. When the fluidity is high, the precipitated starch is easily carried to the lower part by the water at the interface, resulting in too much starch paste and excessive viscosity at the lower part, making it difficult to separate the rice at the lower part from the inner pot.

[0074] Since the boundaries of the gullies are ridges, the height difference of the gully boundaries is not unique, some are high and some are low. When the starch liquid in a gully with a certain direction reaches a certain amount, the relatively low-lying part of the ridge will no longer be able to block the starch liquid, and it will overflow from the current gully to another gully with a different direction; the starch liquid in the gullies with different directions are interconnected, which can make the flow domain of the starch liquid and the surface of the inner pot substrate extremely complex, making it difficult for the precipitated starch to be carried to the lower part by the moisture at the interface, thereby ensuring that the starch paste in the lower part is appropriate, and then ensuring that the rice is easily separated from the inner pot.

[0075] In some specific embodiments of the present application, as shown in Figure 6, the ridge body includes a main vein 305 and a branch vein 306 extending in a vein-like manner. The direction of the main vein 305 is the overall direction of the ridge body, and the direction of the branch vein 306 is the secondary direction of the ridge body. The extended end of the ridge body is another ridge body or a gully.

[0076] When viewed along the Z direction in the XY plane, the specific orientation of the rib body can be divided into primary and secondary. The primary vein determines the overall orientation of the rib, while the secondary veins determine the secondary orientation of the rib. While there is only one overall orientation, there can be multiple secondary orientations. It should be understood that the length of the rib body in the extension direction can be used to determine whether it is a primary vein or a secondary vein. The longer extension can be considered the primary vein, and the others can be considered secondary veins.

[0077] The main vein can mainly play a supporting role for rice and is the main dividing direction. The two sides of the main vein are large-area ridges, which means that the gullies will generally be distributed along the extension direction of the main vein; the branch veins can further form secondary dividing directions based on the main vein, or they can further form secondary dividing directions independently of the main vein, thereby making the direction of the gullies more complex; in addition, the main vein and branch veins can further increase the possibility of cross-linking between the ridge bodies, thereby forming ridges with complex structures, so as to form complex watersheds and delay the possibility of starch being transported to lower places.

[0078] In some specific embodiments of the present application, as shown in Figure 6, the same ridge has at least two peaks, and the two peaks are connected by a ridge body 303. The connection forms a low-lying portion 304 of the ridge, and the low-lying portion 304 is surrounded by the grooves 400 on the left and right. 301 is one of the peaks, and 302 is the other peak.

[0079] The ridges have multiple peaks, which can make the ridges undulate, especially the ridge surfaces undulate, to form low-lying parts. The low-lying parts are higher than the bottoms of the gullies and lower than the peaks. The low-lying parts facilitate the interconnection between the gullies, so that the gullies can accommodate a certain amount of starch liquid while also being able to overflow when a certain amount is stored. The starch stored in the gullies will precipitate when the temperature drops, and under the action of gravity, the turbid ones will sink, making the liquid on the surface of the gullies relatively clear, and the overflow is the clear liquid. The clear liquid flows out because it carries less starch, so it will not cause any problem to the rice at the bottom of the inner pot, thus keeping it non-stick.

[0080] In some specific embodiments of the present application, the bite pattern is distributed at different potential energy positions of the inner liner, the potential energy positions include high potential energy positions and low potential energy positions, and the bottom of the inner liner includes at least a low potential energy position.

[0081] As mentioned above, due to the interconnected and crisscrossing grooves and ridges, the flow field of condensed water becomes extremely complex. Although the complex flow field formed is inconvenient for transporting starch to lower places, the complex flow field also increases the difficulty of transporting water, that is, it greatly hinders the bottom of the inner pot from obtaining water in time. Because the bottom of the inner pot is mostly where the heating device is located, it is a heat accumulation area. The temperature difference between the inside and outside of the interface here is small, and the heating device often provides heat to heat up the bottom of the inner pot, so it is difficult to form enough condensed water at the interface here to keep it non-stick.

[0082] After cooking is completed, the condensed water formed at the interface can flow according to the potential energy of the interface. Different potential energy positions have different gravitational potential energies. Setting bite patterns at different potential energy positions can, on the one hand, make the overall flow direction of the starch liquid flow toward the bottom of the inner pot to replenish water to the bottom, and on the other hand, keep the starch precipitate at the high potential energy position, so that it is not easy to accumulate too much sticky starch paste at the low potential energy position.

[0083] Potential energy positions include high potential energy positions and low potential energy positions, and the bottom of the inner liner includes at least a low potential energy position. The substrate surface of the inner liner bottom can be flat or curved, and the inner liner bottom can include both a curved portion and a flat bottom portion. In this case, the bottom of the inner liner can have high potential energy positions and low potential energy positions. The bottom of the inner liner can also be entirely low potential energy positions, while the high potential energy position is the side wall portion of the inner liner. The side wall portion can be straight or spherical, and this application does not impose any restrictions.

[0084] In some specific embodiments of the present application, as shown in the figure, the ridges include first-level ridges and second-level ridges, and the gullies include first-level gullies and second-level gullies. The maximum height of the first-level ridges is greater than the maximum height of the second-level ridges, and the maximum depth of the first-level gullies is greater than the maximum depth of the second-level gullies. Specifically, the first-level ridges may be higher than 1 / 4 of the maximum height difference, and the first-level gullies may be deeper than 1 / 4 of the maximum height difference.

[0085] In order to enable the ridges to effectively support the rice, the ridges have large-sized first-level ridges to support the rice. Correspondingly, the grooves have large-sized first-level grooves, so that the grooves can accommodate a certain amount of starch sediment and condensed water to allow clear liquid to flow out and turbid matter to sink; small-sized second-level ridges and second-level grooves can facilitate the formation of a Cassic infiltration state.

[0086] It should be understood that the height of the ridges varies, and the depth of the grooves is similar to the height of the ridges, and varies from place to place, and cannot be defined by a single depth dimension. The depth of the grooves can be defined by the maximum depth, and the height of the ridges can be defined by the maximum height.

[0087] In some specific embodiments of the present application, second-level ridges and second-level grooves are further provided on the first-level ridges; and second-level ridges and second-level grooves are further provided in the first-level grooves. Specifically, a portion of the second-level ridges and a portion of the second-level grooves are provided on the first-level ridges; another portion of the second-level ridges and another portion of the second-level grooves are provided in the first-level grooves.

[0088] Gullies and ridges are repeatedly arranged in the gullies, so that the large-sized gullies have small-sized ridges and gullies inside. These small-sized ridges and gullies have the function of Cassic infiltration, thereby preventing the starch precipitated in the gullies from firmly adhering to the gully surface; grooves and ridges are repeatedly arranged on the ridges, making it difficult for rice to come into close contact with the ridges, so that the rice can be separated from the inner pot.

[0089] In some specific embodiments of the present application, along the first extension direction of the first-level ridges, at least part of the length of the first-level ridges is within 500 microns, and the height fluctuation range between the second-level ridges and the second-level grooves thereon is within 3 microns; and / or, along the first extension direction of the first-level grooves, at least part of the length of the first-level grooves is within 500 microns, and the height fluctuation range between the second-level ridges and the second-level grooves thereon is within 3 microns.

[0090] Specifically, the first extension direction is the length or width direction on the XY plane.

[0091] The first extension direction of the first-level ridge can be the extension direction of the main vein, or the width direction of the main vein; or the extension direction of the branch vein, or the width direction of the branch vein; or the width direction of the peak.

[0092] The first extension direction of the first-level gully may be a length direction of the gully or a width direction of the gully.

[0093] The length of the first-level ridges or first-level grooves at the large-size level is within 500 microns, and the height fluctuation range between the second-level ridges and the second-level grooves at the small-size level is within 3 microns. Micro-topography with a height fluctuation range of 3 microns is formed on the large-size ridges or in the grooves, which helps to form a Cassic infiltration state.

[0094] In some embodiments of the present application, at least some of the gullies form basin-like features, and at least some of the basin-like features have a width exceeding 150 microns and a depth exceeding 7 microns. The basin-like features are surrounded by ridges, making it more difficult for starch to flow out, and after precipitation, clear liquid can flow out to soak the lower areas.

[0095] In some embodiments of the present application, the surface of the textured surface is heat-treated or vapor-deposited to form a protective layer, wherein the thickness of the protective layer is less than the maximum depth of the grooves. The protective layer helps to improve the wear resistance of the surface of the stainless steel substrate, thereby extending the life of the non-stick property.

[0096] Some specific embodiments of the present application, such as an uncoated rice cooker as shown in Figures 7-8, include a cooker body 10, the cooker body 10 is provided with a cooling fan 101, and a accommodating cavity 102 for accommodating any of the above-mentioned uncoated non-stick inner pots, the cooker body 10 is provided with a cooker cover 20, the cooling fan 101 is used to introduce cooling airflow into the accommodating cavity 102, and an airflow outlet 103 is provided between the cooker cover 20 and the cooker body 10, wherein the airflow outlet located on the rear side of the cooker body is larger than the airflow outlet on the front side.

[0097] The pot body of this application is equipped with a cooling fan to cool the inner pot. The cooling fan creates condensation between the rice and the inner pot, preventing the rice from sticking. An airflow outlet 103 is provided between the pot body and the lid. The airflow outlet 103 has a flared portion 104 at the hinge (located at the rear of the pot body), making the airflow outlet at the rear of the pot larger than that at the front. The cooling air generated by the cooling fan can ultimately be discharged through the flared portion. The flared portion is located at the hinge and does not affect user experience.

[0098] Referring to Figures 9 to 13, this embodiment provides an uncoated non-stick inner pot, including a stainless steel pot body formed by stretching a plate, the stainless steel pot body having a stainless steel metal layer 100 for contacting the food surface, the inner surface of the stainless steel metal layer 100 having a micron-level texture 106 formed by laser shock, the micron-level texture 106 including ridges and grooves, the ridges and grooves being randomly distributed on the inner surface of the stainless steel metal layer 100, and the roughness of the micron-level texture 106 on the inner wall 120 of the pot body is less than the roughness of the bottom wall 111 of the pot body.

[0099] It should be noted that the random distribution means that the ridges and grooves are not arranged according to any preset rules, and the positions of the ridges and grooves on at least the inner surface of the stainless steel metal layer 100 are disordered. For example, refer to Figures 11 and 12. Figure 11 is a schematic diagram of the 3D morphology of the micron-level bite pattern obtained using the Keyence VHX-7000N digital microscope system. In the figure, "0.00μm", "500", "1000", and "1500" are length dimensions (micrometers). The color contrast on the left represents the height of the morphology, and the values ​​increase from bottom to top. The black area in the figure is a relatively concave part, and the white area is a relatively convex part. The two are not arranged according to any preset rule. Figure 12 is a straight line selected from the micron-level bite pattern for cutting, and a schematic diagram of the outline at the cross-section. It can be seen that in the direction of a straight line, the next unit adjacent to the ridge 109 can be a groove 110, or it can also be a ridge 109, and the next unit adjacent to the groove 110 can be a ridge 109 or a groove 110; alternatively, the spacing between adjacent ridges 109 (or grooves 110) can also be random, some are close, and some are far apart. It is understood that the shapes or sizes of the ridges 109 and grooves 110 may be random, for example, some may be larger, some may be smaller, some may be regular circles, squares, or ovals, and some may be irregular shapes. For example, some grooves may be deep, some may be shallow, some may be high, and some may be low. Of course, the ridges and grooves may also be randomly distributed in terms of position, shape, or size, which is not limited here.

[0100] The stainless steel pot body formed by stretching the plate has a stainless steel metal layer 100 for contacting the food. The inner surface of the stainless steel metal layer 100 is formed with a micron-scale bite pattern 106 with ridges and grooves by laser impact, thereby forming a bionic concave-convex structure similar to a lotus leaf, so that the inner surface of the stainless steel metal layer 100 has a hydrophobic property similar to that of a lotus leaf, and the process is simple and the cost is low. Since the ridges and grooves of the micron-scale bite pattern are randomly distributed, it is easier to form relatively large concave and convex parts on a micron scale. As shown in FIG11 , in the early stage of rice cooking, the concave portion generates heat flow earlier than the convex portion, and local heat convection is formed between the two. Moreover, since the ridges and grooves are randomly distributed, the concave and convex portions formed in the end are also relatively disordered, thereby increasing the probability of convection collision and forming more intense local heat convection, thereby better stirring the rice grains and promoting the rolling of the rice grains, making the rice grains dynamic, and making it difficult for the rice grains to stick to the inner surface of the stainless steel metal layer and not to stick to the inner surface of the stainless steel metal layer 100. At the same time, the water The convex and concave portions formed on the micron scale can reduce the contact area between the rice grains and the inner surface of the stainless steel layer 100, thereby reducing the heat directly transferred to the rice grains. In addition, by making the roughness of the inner wall 120 of the pot body smaller than the roughness of the bottom wall 111 of the pot body, the small amount of water remaining in the late cooking period and the small water droplets formed by the condensation of water vapor are more likely to pass through the opened channels from the inner wall of the pot body, which is less likely to stick, to the higher temperature. , the rice flows along the bottom wall 120 of the pot body which is easy to stick to the rice. While moistening the rice in the flow process, a thin layer of water can also be formed on the bottom. The hydrophobic property makes it difficult for water to penetrate into the concave-convex structure, so that the micron-level bite pattern can use the gas inside it to support the water layer 107 and rice grains 108 (refer to Figure 13), so that more water can moisten the rice for a longer time, reduce the adhesion between the rice and the pot body, reduce the probability of the bottom of the pot body sticking to the pot, make the rice more uniform, and achieve a non-stick effect without coating, which is convenient for users to clean.

[0101] Optionally, the micron-level bite pattern can be formed by a single impact at a smaller laser scanning distance, by two or more impacts at a slightly larger scanning distance, or by random laser beam impacts, which is not limited here.

[0102] It should be noted that the roughness of the micron-level biting pattern 106 on the inner wall 120 of the pot body is smaller than the roughness of the bottom wall 111 inside the pot body. It can be directly formed during processing. For example, surfaces with different roughness can be produced by adjusting parameters such as the laser energy density value. It can also be formed after processing a surface with consistent roughness through post-processing (such as polishing). This is not limited here.

[0103] In some embodiments of the present application, the roughness of the micron-level bite pattern 106 on the bottom wall 111 of the pot body is between 0.8-2.5 μm, such as 0.8, 1, 1.2, 1.6, 1.8, 2, 2.2, 2.5 microns, etc., and the roughness of the micron-level bite pattern 106 on the inner wall 120 of the pot body is between 0.4-2.0 μm, such as 0.4, 0.5, 0.8, 1, 1.2, 1.6, 1.8, 2 microns, etc.

[0104] Setting the roughness of the pot's inner bottom wall 111 within the range of 0.8-2.5 μm achieves superior non-stick and hygienic properties. A roughness less than 0.8 μm results in too little air trapped within the micron-scale grain pattern, potentially reducing the ultimate support. A roughness greater than 2.5 μm can easily trap food residue or rice starch particles within the micron-scale grain pattern, hindering the cleanliness of the stainless steel inner surface. Setting the roughness of the pot's inner wall 120 within the range of 0.4-2.0 μm results in a relatively smooth inner wall, reducing the likelihood of rice grains sticking to the inner surface of the stainless steel layer 100 and facilitating heat flow to agitate the rice grains, thereby opening up water and steam channels.

[0105] Preferably, the roughness of the micron-level bite pattern 106 on the bottom wall 111 of the pot body is between 1-2 μm, and the roughness of the micron-level bite pattern 106 on the inner wall 120 of the pot body is between 0.8-1.6 μm, so as to balance the gas and residue contained in the micron-level bite pattern, thereby obtaining better non-stick effect and hygienic performance, and also facilitating manufacturing and molding.

[0106] In some embodiments of the present application, referring to FIG9 and FIG10 , the mouth of the stainless steel pot body is provided with a flange 200 , and the roughness of the micron-level biting pattern 106 gradually decreases from bottom to top on the inner wall 120 of the pot body to the flange 200 .

[0107] During the cooking process, the temperature at the bottom wall 111 of the pot body is generally the highest, and heat is gradually transferred upward from the bottom. By gradually reducing the roughness from bottom to top, the micron-level bite pattern 106 can be more in line with the heat transfer path and distribution, and the higher temperature parts can have a better supporting effect. At the same time, it can also make the water at the inner wall 120 of the pot body flow more smoothly to the higher temperature part, further improving the uniformity of the rice and the non-stick effect of no coating.

[0108] In some alternative embodiments of the present application, the roughness of the micron-scale textured pattern 106 in the middle portion 122 of the pot inner wall is less than that in the lower portion 123 of the pot inner wall, and / or the roughness of the micron-scale textured pattern 106 in the upper portion 121 of the pot inner wall is less than that in the lower portion 123 of the pot inner wall. The lower portion 123 of the pot inner wall is close to the pot inner bottom wall 111, where heat is relatively concentrated, making it prone to sticking. This arrangement facilitates the flow of moisture from above the lower portion 123 of the pot inner wall toward it, ensuring that the moisture effectively moistens the rice in this area during the flow, reducing the likelihood of rice sticking there and improving the uniformity of the rice.

[0109] Specifically, referring to Figure 10, the inner bottom wall 111 of the pot body is located on the inner side of the bottom of the pot body, and is generally a plane or a curved surface that is slightly raised toward the center and has a certain curvature. The lower part 123 of the inner side wall of the pot body is an arc-shaped section extending upward from the edge of the inner bottom wall 111 of the pot body. The upper part 121 of the inner side wall of the pot body is located at the top of the inner side wall of the pot body and is connected to the flange 300. The middle part 122 of the inner side wall of the pot body connects the upper part 121 of the inner side wall of the pot body and the lower part 123 of the inner side wall of the pot body. It can be in the form of protruding outward or in the form of being basically vertical.

[0110] In some embodiments of the present application, the grooves envelop the ridges, and adjacent ridges in the circumferential direction of the pot body have different shapes, and the adjacent ridges at least partially overlap. The "at least partially overlap" means that the projections of the two ridges in the circumferential direction overlap.

[0111] The ridges of different shapes and the grooves surrounding the ridges can increase the disorder of the micron-level bite pattern 106, and the at least partially overlapping arrangement of two adjacent ridges can further increase the probability of heat flow convection collision, which is conducive to forming more intense local heat convection, better promoting the rolling of rice grains, and improving the non-stick properties of cooking utensils.

[0112] In some embodiments of the present application, the grooves are randomly distributed in both the circumferential direction and the axial direction of the pot body, and / or the ridges are randomly distributed in both the circumferential direction and the axial direction of the pot body.

[0113] The random distribution in both the circumferential and axial directions further enhances the disorder of the micron-scale bite pattern 106, thereby making the local heat convection between the relatively concave part and the relatively convex part more intense, improving the dynamics of the rice grains, making it less likely for the rice grains to stick to the inner surface of the stainless steel metal layer 100, and also facilitating the opening of water and steam channels, thereby improving the non-stick performance and the uniformity of the rice.

[0114] It should be noted that the circumferential direction and the axial direction may be two directions perpendicular to each other, or may be two directions forming an acute angle or an obtuse angle, which is not limited here.

[0115] Of course, the above embodiments do not mean that the present application excludes the case of random distribution in only one direction, and those skilled in the art may make a choice according to actual conditions.

[0116] In some embodiments of the present application, at least one of the shape and height of two adjacent ridges is different, and / or at least one of the shape and depth of two adjacent grooves is different.

[0117] Such a setting can further improve the disorder of the micron-level bite pattern 106, increase the probability of heat convection collision, form more intense local heat convection, improve the effect of stirring rice grains and promoting rice grain rolling, which is beneficial to the opening of channels and the improvement of non-stick performance. In addition, the difference in ridge height or groove depth also means that even if high ridges or shallow grooves are damaged during long-term use, other ridges or grooves will continue to play a role, thereby ensuring the non-stick performance and long service life of the cooking utensils.

[0118] In some embodiments of the present application, the stainless steel pot body further includes a heat-conducting layer and an outer stainless steel metal layer, and the heat-conducting layer is sandwiched between the stainless steel metal layer 100 and the outer stainless steel metal layer.

[0119] The setting of the stainless steel metal layer and the outer stainless steel metal layer sandwiching the heat-conducting layer can protect the heat-conducting layer at a lower cost, and the heat-conducting layer can evenly distribute heat and store heat. Its even heat distribution effect can improve the thermal uniformity of the pot body, avoid local high temperature causing the rice to burn and stick to the stainless steel metal layer, and further improve the non-stick effect of the uncoated dish.

[0120] Preferably, the stainless steel metal layer is made of food-grade 304 or 316L material, and the outer stainless steel layer can be made of stainless steel suitable for food contact, or other materials, which are not specifically limited here.

[0121] Furthermore, the heat-conducting layer is an aluminum layer, which can improve the thermal conductivity while reducing the weight of the pot body, making it easier for users to take it in and out. Of course, the heat-conducting layer can also be formed by a heat transfer medium such as superconducting liquid, which is not limited here.

[0122] In some embodiments of the present application, the surface of the micron-scale textured pattern 106 is provided with a protective layer formed by heat treatment or vapor deposition. For example, physical vapor deposition (PVD), nitriding, etc. can be used; of course, other heat treatment or vapor deposition methods can also be used to form the protective layer, which is not limited here. The provision of a protective layer can improve the surface properties of the pot body, preventing scratches from food and spatulas during long-term use that damage the micron-scale textured pattern, resulting in a loss of hydrophobicity and non-stick properties, thereby extending the service life of the cooking utensil.

[0123] Preferably, the thermal conductivity of the protective layer is not less than that of the stainless steel metal layer, so that the heat can be conducted more evenly to improve the uniformity of heating and the consistency of the rice.

[0124] 14 and 15 , an embodiment of the present application further provides an uncoated rice cooker, comprising a cooker body 3001 and a cooker lid 4001 disposed on the cooker body 3001, wherein the cooker body 3001 is provided with a fan assembly 3010 and a receiving cavity 3020 for accommodating the uncoated non-stick liner. The fan assembly 3010 is used to introduce cooling airflow into the receiving cavity 3020, and an airflow outlet is provided between the cooker lid 4001 and the cooker body 3001, wherein the airflow outlet located at the rear side of the cooker body is larger than the airflow outlet located at the front side of the cooker body.

[0125] At the end of cooking, the fan assembly 3010 introduces cooling airflow into the accommodating chamber 3020, rapidly lowering the temperature of the uncoated non-stick inner pot in the accommodating chamber 3020. This promotes the liquefaction of water vapor in the rice pores to produce more moisture, improves the wetting effect of the side water on the rice during flow, ensures the formation of a bottom water layer, and thus more fully soaks the rice, reduces the adhesion between the rice and the pot body, further reduces the probability of the pot body sticking to the pot, and improves the uncoated non-stick effect. Furthermore, during the use of the uncoated rice cooker, the user generally observes and operates the pot body from the front side. By making the airflow outlet on the rear side of the pot body larger than the airflow outlet on the front side of the pot body, the cooled diverted air can be more easily and more efficiently discharged from the rear side of the pot body, reducing the impact of the airflow on the user at the front side of the pot body.

[0126] Specifically, the airflow outlet located on the front side of the pot body is the air outlet gap 6001, which is formed by the gap between the lower surface of the pot cover and the upper surface of the pot body when the pot cover 4001 is closed on the pot body 3001. The airflow outlet located on the rear side of the pot body is the air outlet 5001, which is formed by the outward expansion of the gap between the pot cover 4001 and the pot body 3001. For example, the lower surface of the pot cover is tilted upward to form a flared opening between the upper surface of the pot body, or the upper surface of the pot body is tilted downward to form a flared opening between the lower surface of the pot cover, etc.

[0127] This application does not limit the air outlet position of the fan assembly 3010. It can be set at the bottom of the accommodating cavity 3020. It can be a separately opened air outlet, or it can be a gap generated after the existing structure is assembled, such as the gap between the insulation ring of the pot body and the coil disk, etc., which is not limited here.

[0128] In some alternative embodiments of the present application, the uncoated rice cooker may not adopt the above-mentioned air cooling solution, but may adopt natural cooling or other cooling methods.

[0129] It should be noted that the above embodiment is described with reference to an uncoated rice cooker, which can be an electric rice cooker or a pressure cooker. It is understandable that the uncoated non-stick inner pot in the embodiment of the present application can also be any cooking utensil that can cook rice or has a non-stick requirement, such as an electric stew pot, a frying pan, an air fryer, etc., without limitation herein.

[0130] Referring to the embodiments provided in Figures 16-18 , this embodiment provides an air-cooled, non-coated, non-stick rice cooker comprising an inner pot 1, a pot body 2, and a lid 3. The inner pot 1 is placed within the pot body 2 for holding ingredients to be cooked, such as rice. The lid 3, when closed onto the pot body 2, covers the inner pot 1. When the lid 3 is opened, the ingredients in the inner pot can be removed. The pot body 2 is also provided with a heating device for heating the inner pot 1 to heat and cook the ingredients therein.

[0131] The pot cover 3 of this embodiment is hinged on the pot body 2, that is, the pot cover 3 is rotatably connected to the pot body 2. Specifically, a rotating shaft is provided at the rear part of the pot body 2, passing through the pot cover 3 and the pot body 2, so that the pot cover 3 is hinged on the pot body 2, and a torsion spring is provided on the rotating shaft. When the buckle at the front part of the pot cover 3 is disengaged, the torsion spring will drive the pot cover 3 to rotate so that the pot cover 3 is opened.

[0132] In this embodiment, an air outlet gap is provided between the pot body 2 and the pot lid 3. Referring to Figures 16-18, the air outlet gap has a flared portion 4 at the hinge. A cooling fan 5 for cooling the inner pot is provided in the pot body 2, and the flared portion 4 is used to discharge the cooling air generated by the cooling fan 5. The flared portion 4 can be understood as the air outlet gap being partially enlarged at the hinge, forming a certain flare, so that it is more convenient for the cooling air to be discharged from here. Because the cooling air needs to be discharged from the air outlet gap when it is within the pot body, and the gap of the flared portion is significantly larger than the air outlet gaps in other areas, more cooling air will be discharged from the flared portion. Specifically, the gap at the flared portion is more than five times the air outlet gap in other areas. For example, the air outlet gap is about 0.5 mm, and the height of the flared portion is more than 2.5 mm.

[0133] In this embodiment, because the lid 3 is closed on the pot body 2 and is prevented from separating from the pot body by a snap fastener, a closing gap is formed between the lid 3 and the pot body 2. Due to the action of the torsion spring, the lid 3 has a tendency to open, causing the closing gap at the front (i.e., the air outlet gap in this application) to be larger. However, this application provides a flared portion 4 at the hinge, and the gap of the flared portion 4 is larger than the closing gap, so that the cooling air generated in the pot body 2 is discharged from the flared portion 4. During operation, when the cooling fan 5 generates cooling air to cool the inner pot 1, part of the cooling air will flow upward and be discharged from the bottom of the inner pot flange, and then discharged from the air outlet gap between the pot body 2 and the lid 3. Since the flared portion has a larger flare, the cooling air will be discharged from this point to the outside of the machine. Since the flared portion is located at the hinge, that is, on the side away from the user, it will not affect the user's use of the rice cooker.

[0134] In this embodiment, as shown in Figures 16 and 17 , the inner pot is provided with a flange, and the pot body 2 is provided with a plurality of protrusions 6 that support the flange, with an air passage formed between adjacent protrusions. After cooling the inner pot, the cooling air generated by the cooling fan 5 flows through the air passage to the joint between the pot lid 3 and the pot body 2, that is, to the air outlet gap, and then flows out through the air outlet gap. The flared portion 4 is located at the hinged portion at the rear of the pot body, and more cooling air flows out through the flared portion 4. The provision of the air passage ensures that the cooling air flows upward from the inner pot as much as possible, while the heating device is generally located below the inner pot, thereby avoiding energy loss to a certain extent.

[0135] The operating principle of cooling fan 5 is that during the later stages of rice cooking, specifically during the simmering or warming stages, cooling fan 5 cools the inner pot. Due to the sudden drop in the inner pot temperature, condensation forms between the inner pot and the rice, preventing the rice from sticking. The continuous operation of cooling fan 5 continuously injects cooling air, which flows along the outer wall of the inner pot, passes through the air passage, and is ultimately discharged through the air outlet gap, particularly from flared portion 4.

[0136] In this embodiment, the inner pot 1 comprises a metal layer for contacting the rice, and the surface of this metal layer is provided with hydrophobic concave and convex features. Since the metal layer of the inner pot 1 directly contacts the rice, the inner pot 1 does not require a chemical coating, unlike existing coated inner pots. Preferably, the metal layer of this embodiment is provided with randomly distributed hydrophobic concave and convex features. This arrangement imparts a certain degree of hydrophobicity to the inner surface of the inner pot, achieving a physical non-stick effect. More specifically, the concave and convex features are randomly distributed, unlike many prior art designs that are regularly distributed, significantly reducing the process requirements and enabling distributed manufacturing. The concave and convex features can be formed by a plurality of protrusions distributed on the inner pot surface, with the corresponding other areas being considered concave, or by a plurality of grooves distributed on the inner pot surface, with the corresponding other areas being considered convex. It is understood that the inner pot 1 can be composed of multiple layers of metal sheet material, with the metal layer that contacts the rice being the innermost layer, and can be made of stainless steel, eliminating the need for a chemical coating such as Teflon.

[0137] In the present embodiment, random distribution has at least the following understandings: first, the position of the protrusions or grooves on the surface of the metal layer is randomly distributed. The spacing between adjacent protrusions (or grooves) can be random, some are close together, and some are far apart. It is also possible that the size of the protrusions or grooves on the surface of the metal layer is randomly distributed, some are too large, and some are too small. It is also possible that their shape is random, and can be a regular circle, square, oval, or an irregular shape. The second is that the depth of the grooves or the height of the protrusions in the hydrophobic concave-convex portion are randomly distributed, and some grooves are too deep, and some grooves are too shallow, and some protrusions are too high, and some protrusions are too short. Of course, it is also possible to have both random position distribution and random depth or height distribution, both of which are available. Due to the randomness of random distribution, the process difficulty is reduced.

[0138] In this embodiment, the surface roughness of the metal layer is 0.4-2.5 μm. Within this range, excellent non-stick and hygienic properties can be achieved. If the roughness is less than 0.4 μm, the air in the grooves will be too small, which will easily reduce the final rice support effect. If the roughness is greater than 2.5 μm, food residue or rice starch particles will easily remain in the grooves, which is not conducive to cleaning the inner surface of the stainless steel metal layer.

[0139] In this embodiment, the height difference of the hydrophobic concave and convex portions is smaller than the height of the flared portion. The height difference of the hydrophobic concave and convex portions affects the rice's non-stick properties, while the height of the flared portion determines the speed at which cooling air is discharged, which also affects the formation of a moist film and the rice's non-stick properties. By integrating these two factors, an excellent non-stick effect can be achieved. In other words, a smaller height difference of the hydrophobic concave and convex portions, combined with a larger height of the flared portion, results in better non-stick properties on the inner pot surface and allows for smooth and timely discharge of cooling air.

[0140] In this embodiment, the height difference of the hydrophobic concave and convex portions is on the micron scale. That is, the difference between the highest and lowest points of the concave and convex portions is on the micron scale. Specifically, the micron scale should be understood as 1-999 microns. A micron-scale height difference can meet the non-stick performance requirements of rice and is also easy to manufacture and shape. In contrast, conventional concave and convex portions are often on the millimeter scale, which can easily lead to rice starch residue, making cleaning inconvenient and affecting the user experience.

[0141] In this embodiment, referring to Figure 18 , the lid has upwardly sloping surfaces or air guides on either side of the hinge. These surfaces cooperate with the pot body to form a flared portion 4, which serves as an air outlet. Specifically, the lid has the sloping surfaces or air guides at the hinge, while the pot body is essentially horizontal. When the lid is closed, the flared portions 4 are formed on the sloping surfaces or air guides. The provision of flared portions 4 not only facilitates the orderly discharge of cooling air but also facilitates the rotation of the lid, ensuring that it does not interfere with the pot body.

[0142] In some other embodiments of this embodiment, the pot body is provided with downwardly sloping slopes or air guides on both sides of the hinge. These slopes or air guides cooperate with the pot lid to form a flared portion for the air outlet. Specifically, the pot body has the slopes or air guides at the hinge, while the pot lid is substantially horizontal. When the pot lid is closed over the pot body, the slopes or air guides form flared portions. The provision of the flared portion not only facilitates the orderly discharge of cooling air but also facilitates the rotation of the pot lid, ensuring that it does not interfere with the pot body during rotation.

[0143] In some other embodiments of this embodiment, the lid is provided with upwardly inclined slopes or air guides on both sides of the hinge, and the body is provided with downwardly inclined slopes or air guides on both sides of the hinge. The slopes or air guides on the lid cooperate with the slopes or air guides on the body to form a flared portion for the air outlet. In other words, both the lid and the body have a certain inclination, forming a more pronounced flared portion, which facilitates the orderly discharge of cooling air and also facilitates the rotation of the lid, ensuring that it does not interfere with the body during rotation.

[0144] Anything not described in this application can be achieved by adopting or drawing on existing technologies.

[0145] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0146] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A non-stick liner without coating, comprising a stainless steel liner formed by stretching a sheet material, characterized in that: The inner stainless steel substrate surface of the stainless steel liner is laser-impacted to form a micron-scale textured pattern, wherein the micron-scale textured pattern includes ridges and grooves, and the ridges and grooves are randomly distributed on the substrate surface, and the height difference between the ridges and grooves is randomly fluctuated within 20 μm.

2. The uncoated non-stick liner according to claim 1, characterized in that: The substrate surface includes an inner wall surface and a bottom surface, and the height difference between ridges and grooves on the inner wall surface is randomly fluctuated within 15 μm.

3. The uncoated non-stick liner according to claim 1, characterized in that: The substrate surface includes an inner wall surface and a bottom surface, and the maximum height difference between the ridges and the grooves on the bottom surface is greater than the maximum height difference between the ridges and the grooves on the inner wall surface.

4. The uncoated non-stick liner according to claim 1, characterized in that: The ridge includes a ridge body and a peak portion, the peak portion is located on the top side of the ridge body, the surface of the ridge body and the surface of the peak portion form an edge facet, the edge facet extends from the peak portion to one side of the gully, the gully is bounded by the edge facet, and the directions of different ridge bodies on the surface of the substrate are different.

5. The uncoated non-stick liner according to claim 1, characterized in that: The biting patterns are distributed at different potential energy positions of the inner liner, the potential energy positions include high potential energy positions and low potential energy positions, and the bottom of the inner liner includes at least a low potential energy position.

6. The uncoated non-stick liner according to claim 1, characterized in that: The ridges include first-level ridges and second-level ridges, and the grooves include first-level grooves and second-level grooves. The maximum height of the first-level ridges is greater than the maximum height of the second-level ridges, and the maximum depth of the first-level grooves is greater than the maximum depth of the second-level grooves.

7. The uncoated non-stick liner according to claim 6, characterized in that: A portion of the second-level ridges and a portion of the second-level grooves are provided on the first-level ridges; Another portion of the second-level ridges and another portion of the second-level grooves are arranged in the first-level grooves.

8. The uncoated non-stick liner according to claim 7, characterized in that: Along the first extension direction of the first-level ridges, the length of at least part of the first-level ridges is within 500 microns, and the height fluctuation range between the second-level ridges and the second-level grooves provided on the first-level ridges is within 3 microns; and / or, Along the first extension direction of the first-level grooves, the length of at least part of the first-level grooves is within 500 microns, and the height fluctuation range between the second-level ridges provided on the first-level grooves and the second-level grooves is within 3 microns.

9. The uncoated non-stick liner according to claim 1, wherein: At least part of the gullies forms a basin-like topography, and at least part of the basin-like topography has a width exceeding 150 microns and a depth exceeding 7 microns.

10. A non-coating rice cooker, comprising a rice cooker body, characterized in that: The pot body is provided with a cooling fan and a receiving cavity for accommodating the uncoated non-stick inner pot according to any one of claims 1 to 9. The pot body is provided with a pot cover. The cooling fan is used to introduce cooling airflow into the receiving cavity. An airflow outlet is provided between the pot cover and the pot body, wherein the airflow outlet located on the rear side of the pot body is larger than the airflow outlet on the front side.

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