Rice cooker inner pot and cooking utensils

Abstract

The present invention provides an inner pot for a rice cooker, the inner pot including an inner metal layer, the surface of which is provided with a plurality of grooves, the depth of the grooves being 0.04-0.15 mm, and the inner metal layer is provided with a metal protective film for reducing its surface energy, the thickness of the metal protective film within the grooves being 0.5%-2% of the depth of the grooves. The inner pot of the present invention can be easily cleaned. The present invention also provides a cookware having the above inner pot.

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application filed with the China Patent Office on February 14, 2023, bearing application number CN202310111993.9 and entitled "Rice Cooker Inner Pot and Cooking Utensil," the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the technical field of kitchen appliances, and more particularly to an inner pot and cooking utensil for rice cooking. [Background technology]

[0003] In prior art inner pots, a chemical non-stick coating such as Teflon® is typically applied to the inner surface of the inner pot to achieve non-stick properties. Chemical coatings such as Teflon are widely used in utensils such as woks, grills, rice cooker inner pots, and air fryer baskets. However, a drawback of chemical coatings such as Teflon is that they tend to fall off, especially after prolonged use or when scrubbed with hard materials. Once the coating falls off, the non-stick performance of the pot is severely affected. To extend the service life of the pot, it is generally not recommended to clean pots with chemical non-stick coatings with hard materials such as metal scrubbers. Removing the chemical coating, such as Teflon, significantly reduces the non-stick performance, affecting the user experience and requiring improvement.

[0004] In the prior art, one solution to the problem of chemical coatings such as Teflon peeling off is to create grooves on the surface of the pot and then place a chemical coating such as Teflon inside the grooves, thereby preventing the coating from peeling off. However, this structure still leaves the chemical coating present.

[0005] In the prior art, another solution is to provide multiple protrusions on the surface of the pot to reduce adhesion and achieve non-stick effect, however, with such structure, liquid will flow at the low points, which will affect the non-stick performance and therefore need improvement. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem that the present invention aims to solve is to overcome the deficiencies of the prior art by providing an inner pot for a rice cooker that is easy to clean. [Means for solving the problem]

[0007] In order to solve the above technical problems, the technical solution of the present invention is as follows: An inner pot for a rice cooker includes an inner metal layer, the surface of which is provided with a plurality of grooves that are independent of each other, each groove having a depth of 0.04 to 0.15 mm, and the inner metal layer is provided with a metal protective film, the thickness of which within the grooves is 0.5% to 2% of the depth of the grooves.

[0008] In one embodiment of the present invention, the hardness of the surface of the metal protective film is greater than the hardness of the surface of the inner metal layer.

[0009] In one embodiment of the present invention, the thickness of the metallic protective film is 0.5 μm to 2.5 μm.

[0010] In one embodiment of the present invention, there is a support rib between the grooves, and the width of the support rib is greater than the depth of the grooves.

[0011] In one embodiment of the present invention, the width of the support rib is smaller than the width of the groove. In one embodiment of the present invention, the roughness in the groove is greater than the roughness of the support rib.

[0012] In one embodiment of the present invention, the width of the groove is greater than the depth of the groove. In one embodiment of the present invention, the groove is formed by etching, laser engraving, or press molding.

[0013] In one embodiment of the present invention, the metallic overcoat is coated onto the inner metal layer by physical vapor deposition.

[0014] In one embodiment of the present invention, the area where the plurality of grooves are distributed covers more than two-thirds of the inner surface of the pot.

[0015] The present invention further provides a cooking utensil, which includes a pot body and a pot lid, and an inner pot is provided within the pot body, which is the inner pot of the rice cooking utensil described above. [Effects of the Invention]

[0016] The present invention has the following beneficial effects: 1. The inner pot of the rice cooker proposed by this invention includes an inner metal layer, the surface of which is provided with a plurality of independent grooves. The arrangement of the grooves increases the contact area of ​​the pot and thus the heating area. The depth of the grooves is 0.04-0.15 mm. The shallow depth prevents rice starch particles from remaining and facilitates cleaning. The inner metal layer is provided with a metal protective film, which reduces the metal surface energy, making the inner surface of the inner pot more stable and preventing rice starch particles from remaining and sticking. The thickness of the metal protective film within the grooves is 0.5%-2% of the groove depth. The thickness of the metal protective film is much smaller than the groove depth, preventing the grooves from being filled by the metal protective film and ensuring the existence of the grooves. The relationship between the thickness of the metal protective film and the depth of the grooves, combined with the reduction of the surface energy of the inner pot surface, reduces the contact area of ​​rice starch particles, weakens the force, and makes them more susceptible to water wetting, improving non-stick properties. The metal protective film is not a traditional chemical coating such as Teflon, and is therefore less likely to come off during cleaning. The presence of multiple independent grooves allows steam to condense on the inner pot wall after cooking, and the grooves trap the condensed water, providing a certain degree of isolation between the rice and the inner pot surface, creating a non-stick effect. The grooves trap the condensed water, reducing the chance of it gathering, preventing watery rice and improving the consistency of the rice's texture. Furthermore, the thickness of the metal protective film must be rationally determined to reduce the depth of the grooves; otherwise, the water storage space in the grooves would be reduced, leading to rice sticking.

[0017] 2. The hardness of the metal protective film is greater than that of the inner metal layer. The provision of the metal protective film significantly improves the wear resistance of the pot, allowing the pot to be cleaned with hard materials such as a metal scrubber.

[0018] 3. Between the grooves are support ribs, the width of which is greater than the depth of the grooves. The support ribs are located higher on the inner surface of the pot, while the grooves are located lower. By making the support ribs wider, the probability of rice starch particles remaining in the grooves can be reduced.

[0019] 4. The roughness of the groove is greater than that of the support rib. The rough surface of the hydrophobic material reduces the contact area with contaminants, weakening the force and making the groove less susceptible to contamination.

[0020] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

[0021] The present invention will be further described below in conjunction with the drawings. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram of a cooking utensil according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram of a pot lid and a pot combined according to an embodiment of the present invention. [Figure 3] FIG. 3 is a locally enlarged view of a portion A in FIG. 2. [Figure 4] FIG. 3 is a locally enlarged view of a portion B in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention provides an inner pot for a rice cooker, which includes an inner metal layer having a plurality of grooves on the surface thereof, the grooves having a depth of 0.04 to 0.15 mm, and a metal protective film on the inner metal layer to reduce its surface energy, the thickness of the metal protective film within the grooves being 0.5% to 2% of the depth of the grooves. The present invention also provides a cookware having the above inner pot. The use of the inner pot of the present invention improves the non-stick properties of the inner pot, making it easier to clean.

[0024] The following describes the technical solutions of the embodiments of the present invention in conjunction with the drawings of the embodiments of the present invention, however, the following examples are not all examples of the present invention but only preferred ones. Based on the examples in the embodiments, any other examples obtained by those skilled in the art without exerting any inventive effort are also within the scope of protection of the present invention.

[0025] Example 1 Referring to Figures 1 to 3, this embodiment presents an inner pot for a rice cooker, where the inner pot 3 includes an inner metal layer 32 and a cavity for containing rice. The rice cooker may be a rice cooker or an electric pressure cooker, and includes an inner pot for containing rice. Of course, the inner pot of the present invention may also be called a pot. The technology of this solution may also be applied to other pots, such as woks, pots with handles, and grills, provided that there is no conflict. In this embodiment, the inner pot of a cooker such as a rice cooker or an electric pressure cooker is taken as an example. The inner pot is formed by a composite of multiple metal materials. The inner metal layer in this embodiment is the innermost metal layer of the inner pot. For example, the inner pot in this embodiment is formed by a three-layer composite of steel, aluminum, and steel, with the middle layer made of aluminum to improve thermal conductivity. The innermost steel layer is the inner metal layer in this embodiment. See Figure 3, that is, the inner pot includes an inner metal layer 32, a soaking aluminum layer 33, and an outer stainless steel layer 34. Of course, in other embodiments, the inner pot may be a two-layer structure (aluminum and steel), with the exterior coated with a protective material such as organic silicone, and the aluminum or steel inner layer is the inner metal layer of this embodiment. The inner pot may also be a single layer of aluminum, steel, or other metal, with this single layer being the inner metal layer of this embodiment. Preferably, the inner metal layer 32 of this embodiment is an inner stainless steel layer, with a plurality of independent grooves 5 formed on the surface of the inner metal layer. The grooves 5 increase the contact area of ​​the inner pot and further increase the heating area. The depth of the grooves is 0.04 to 0.15 mm, and their shallow depth prevents dirt accumulation and facilitates cleaning. The independent grooves provide a certain degree of water retention. The inner metal layer is provided with a metal protective film 35, which reduces its surface energy, making the inner surface of the inner pot more stable, preventing rice starch particles from adsorbing and remaining, and making the surface easier to clean. The thickness of the metal protective film 35 within the grooves is 0.5% to 2% of the depth of the grooves. The thickness of the metal protective film 35 is much smaller than the depth of the grooves; specifically, in this embodiment, the thickness of the metal protective film is less than 2% of the depth of the grooves, so the placement of the metal protective film has little effect on the depth of the grooves, avoiding the grooves being filled and ensuring the existence of the grooves.The additional metal protective film reduces the surface energy of the inner surface of the pot. By combining the depth of the grooves with the thickness of the metal protective film and the relationship between the groove depth and the depth, the contact area with contaminants is reduced, the force is weak, and the metal protective film is easily wetted by water. When water droplets roll over the surface, contaminants are easily removed, resulting in a certain degree of self-cleaning properties. The metal protective film in this embodiment is not a conventional chemical coating such as Teflon, so it is difficult to remove even during cleaning. The presence of multiple independent grooves allows a certain amount of moisture to remain in the grooves after cooking as the rice grains absorb water and expand to form rice, providing a certain degree of isolation between the rice and the inner pot surface, improving the non-stick properties of the rice. Assuming the groove depth is consistent, the thickness of the metal protective film should not be too large; otherwise, it will reduce the water storage space in the grooves, causing the rice to stick.

[0026] According to the technical solution of this embodiment, the principle of the rice cooker is mainly as follows: first, the metal layer on the inner surface of the inner pot has a number of grooves 5, the depth of the grooves is 0.04-0.15 mm, and the thickness of the metal protective film is less than 2% of the depth of the grooves. Therefore, the installation of the metal protective film has little effect on the physical function of the grooves. The physical function of the grooves is mainly as follows: the diameter of water droplets is about 0.2-7 mm, and the depth of the grooves is less than 0.2 mm. Due to the action of their own tension, water droplets form spheres and cannot be completely contained in the grooves. Furthermore, a thin metal protective film is installed on the surface to reduce surface energy, so that water molecules enter and remain in the grooves, creating an isolation and anti-stick effect. The water droplet spheres roll along the metal protective film, easily removing contaminants isolated by the water molecules, and have certain self-cleaning properties. During cooking, when rice grains absorb water and expand to form rice, the rice grains are significantly larger than the grooves, forming a certain storage space between the grooves and the rice, and a certain amount of moisture remains, providing a certain isolation effect between the rice and the surface of the inner pot and creating a certain non-stick effect. The hardness of the metal protective film described in this invention is greater than that of the internal metal, and the surface energy is modified to avoid excessive surface energy modification that would reduce the water retention capacity of the grooves. Furthermore, the metal protective film of this invention contains an alloy of calcium, chromium, iron, and nickel, and especially due to the presence of iron, its surface energy is close to that of the internal metal.

[0027] The low surface energy of the metallic protective film 35 and the relationship between its thickness and groove depth are key features of the present invention. The applicant has found through extensive rice testing that, when the metallic protective film material remains constant, different thickness and groove depth ratios affect non-stick performance. Non-stick performance evaluation is based on the national standard GBT 32095.2-2015, entitled "Specifications for Non-Stick Surface Performance and Testing of Metallic Food Cookware for Household Use," Part 2: Non-Stick and Abrasion Resistance Test Standards. The non-stick performance evaluation is quoted in Table 1 below.

[0028] [Table 1]

[0029] In a cooking environment, when other conditions such as the metal protective film material remain unchanged, the thickness of the metal protective film and the depth of the grooves are changed, and the non-stick level evaluation results shown in Table 2 below are obtained according to the above.

[0030] [Table 2]

[0031] As can be seen from the table above, when the groove depth is 0.04~0.15mm and the thickness of the metallic protective film within the groove is 0.5%~2% of the groove depth, the rice meets the national standard of Level II non-stick performance and has good non-stick performance. However, when the thickness / depth is >2%, for example, in Test Examples 6 and 17, the non-stick performance deteriorates significantly, affecting the user experience. Assuming the groove depth is constant, the metallic protective film thickness should not be too large, otherwise it will reduce the water storage space in the groove and deteriorate the non-stick performance.

[0032] In this embodiment, the hardness of the metallic protective film is greater than that of the inner metallic layer, which significantly improves the wear resistance of the inner pot and allows the inner pot to be cleaned with hard materials such as a metal scrubber.

[0033] Referring to Figure 3, in this embodiment, the thickness of the metal protective film is 0.5 μm to 2.5 μm. By making the thickness of the metal protective film much smaller than the depth of the grooves, the grooves can be prevented from being filled by the placement of the metal protective film. The main functions of the metal protective film are to protect the inner metal layer, reduce the surface energy of the inner surface of the inner pot, make the inner surface of the inner pot more stable, reduce the adsorption and retention of rice starch particles, and improve the surface hardness of the inner metal layer, making the inner surface of the pot easier to clean. If the thickness is less than 0.5 μm, processing will be difficult, adhesion will be reduced, and the metal protective film will easily fall off or the coating will be incomplete during processing. If the thickness is more than 2.5 μm, the material of the metal protective film will be wasted and the depth of the grooves will be affected.

[0034] In this embodiment, between the grooves are support ribs 36, the width of which is greater than the depth of the grooves. The support ribs are located higher on the inner surface of the pot, while the grooves 5 are located lower. By making the support ribs wider, the probability of dirt accumulating in the grooves is reduced.

[0035] In this embodiment, the width of the support rib 36 is smaller than the width of the groove, so that the groove is easy to clean due to its large width and small depth.

[0036] Here, in this embodiment, the width of the groove is greater than the depth of the groove, so that processing can be easily performed on grooves of that size level, and deformation due to the support rib having too low strength can be avoided.

[0037] In this embodiment, the roughness of the groove is greater than that of the support rib, and the rough surface of the hydrophobic material reduces the contact area with contaminants, resulting in a weaker force and making the groove less susceptible to contamination.

[0038] In this embodiment, the grooves are formed by etching, laser engraving, or press molding. In the specific process, the plate is processed to form the grooves, and then stretched to form the pot shape.

[0039] In this embodiment, the metal protective film covers the inner metal layer by physical vapor deposition (PVD).

[0040] Physical vapor deposition (PVD) is a method of growing a film on a substrate surface by gasifying a coating material using physical methods (e.g., evaporation, sputtering, etc.). In addition to traditional vacuum evaporation and sputtering growth techniques, PVD also includes various ion beam growth, ion plating, and ion beam assisted growth techniques that have been developed over the past 30 years. Growth types include vacuum evaporation, sputtering plating, and ion plating. Although there are various physical vapor deposition techniques, they all require the realization of three parts of vapor deposition: coating material (target material), gasification, vapor transport, and thin film growth.

[0041] In this embodiment, a physical vapor deposition method is preferably used, in which plasma argon (Ar+) ions and electrons are used to bombard a target material (such as chromium, nickel, or titanium) and sputter the target material in the form of small molecular clusters onto the surface of the pot substrate (internal metal layer). The bond between the substrate surface and the molecular clusters is strong, and the metal bond energy is close to that, so the metal protective layer is difficult to remove. The Vickers hardness of the surface is over 1800, which is much higher than that of the substrate (for stainless steel, the Vickers hardness is about 250), providing good surface density, enhanced non-stick properties, and high wear and scratch resistance. Furthermore, the chemical properties of the metal protective layer are stable, and it does not react or discolor even at high temperatures. Unlike the oxide film formed by chemical reaction in the prior art, the oxide film formed by chemical reaction, when applied to the inner pot of a cookware, is prone to reaction due to cooking various or acidic or alkaline ingredients for a long time, and the oxide film falls off, affecting the service life. In contrast, the metal protective film in this embodiment is formed by physical vapor deposition, which significantly extends the service life.

[0042] In one embodiment of the present invention, the grooves cover more than two-thirds of the inner surface of the pot. The grooves are distributed in the lower regions of the bottom and side walls of the pot, and because they are unlikely to come into contact with food, grooves may also be provided in the upper regions of the side walls, or the grooves may be uniformly distributed on the inner surface of the pot.

[0043] The present invention further provides a cooking utensil, comprising a pot body and a pot lid, wherein an inner pot is provided within the pot body, the inner pot being the inner pot of the rice cooker described above, and a heating device is further provided within the pot body, and the area covered by the plurality of grooves is larger than the area covered by the heating device. Generally, the heating area is the most prone to sticking during cooking, and by arranging a plurality of groove areas larger than the heating area, the non-stick effect can be improved.

[0044] The present invention also provides an air fryer, comprising a pot body and a basket within the pot body, the basket comprising an inner metal layer, the surface of which is provided with a plurality of grooves, each with a depth of 0.04-0.15 mm, and the inner metal layer is provided with a metal protective film to reduce its surface energy, the thickness of the metal protective film within the grooves being 0.5%-2% of the depth of the grooves. The basket incorporating this solution also has a certain degree of non-stick properties, making it easy for users to clean the basket.

[0045] Example 2 This embodiment provides a method for manufacturing a non-stick pot, which can be applied to the inner pot, pot or basket of embodiment 1.

[0046] The manufacturing method of the non-stick pan proposed in this embodiment includes the following steps: Step S1: providing a composite metal plate, the composite metal plate including an outer stainless steel layer, a soaking aluminum layer, and an inner stainless steel layer, and etching, engraving, or pressing the surface of the inner stainless steel layer to form a groove array; Step S2: Pull the composite metal plate provided with the groove array to produce a pot blank, and the groove array is located on the inner surface of the pot blank; Step S3: After polishing and cleaning the inner surface of the pot blank, the cleaned pot blank is subjected to PVD processing to form a metal protective film on the inner surface of the pot blank. The thickness of the metal protective film is 0.5 μm to 2.5 μm, and the thickness of the metal protective film is smaller than the depth of the grooves in the groove array.

[0047] In this embodiment, a nonstick pan is manufactured using a PVD process to form a protective metal layer. The thickness of the protective metal layer is smaller than the depth of the grooves in the groove array, preventing the grooves from being filled by the protective metal layer and ensuring their presence. The additional protective metal layer reduces the surface energy of the inner surface of the pan, reducing the contact area with contaminants and reducing the force of contact. Water droplets easily wet the surface, easily removing contaminants as they roll across it, providing a certain degree of self-cleaning properties. The PVD process strengthens the bond between the substrate surface and molecular clusters, bringing the metal bond energy closer to that of the metal, making the protective metal layer less likely to detach. The Vickers hardness of the resulting surface exceeds 1800, significantly higher than that of the substrate (when the inner metal layer is stainless steel, the Vickers hardness is approximately 250). This provides a dense surface, enhancing nonstick properties and providing high wear and scratch resistance. The pot of this embodiment is formed by a composite of three layers: an outer stainless steel layer, a soaking aluminum layer, and an inner stainless steel layer. The middle aluminum layer provides excellent heat conduction, and the outer or inner stainless steel layer provides magnetic conductivity, realizing electromagnetic heating.

[0048] The method further includes step S4 of laser marking the pot blank with the protective metal film to form scale lines in the groove array, thereby facilitating user use.

[0049] Furthermore, step S3 also includes photoetching or sandblasting the groove array on the inner surface of the pot blank to form a rough surface within the grooves, which improves adhesion and makes it easier for the metal protective film to adhere and less likely to fall off.

[0050] Furthermore, the photoetching or sandblasting treatment may be performed before polishing or before cleaning.

[0051] In this embodiment, the thickness of the protective metal film is 0.8 μm to 1.5 μm. By controlling the thickness within this range, the covering effect of the protective metal film and cost control can be improved.

[0052] In this embodiment, at least some of the grooves in the groove array are circular, oval, or teardrop-shaped, or a combination thereof. The groove array in this embodiment is formed by a plurality of grooves, and the groove shapes may be any of the above-mentioned shapes. Here, the groove shape mainly refers to the cross-sectional shape of the groove. According to the groove shapes of the plurality of shapes, various patterns can be designed to improve the aesthetics of the product.

[0053] In this embodiment, the groove array on the inner surface of the pot blank includes a first array located on the pot bottom and a second array located on the pot wall, and the grooves in the second array are flat. The groove arrays are distributed on both the pot bottom and the pot wall, and the flat grooves in the second array facilitate the flow of liquid on the pot wall and reduce the adsorption effect of the grooves on the liquid.

[0054] This embodiment further presents a non-stick cookware without coating, as shown in Figure 1, which includes a pot body and a non-stick pot installed in the pot body, the non-stick pot is manufactured by the above method, the pot body is equipped with a heating device, and the groove array covers at least the heating device. That is, in this embodiment, the covering area of ​​the groove array is larger than that of the heating device, ensuring that the groove array exists in every heating area. Generally, the heating area is the most prone to sticking during cooking, and the arrangement of the groove array area can improve the non-stick effect.

[0055] 4, the non-stick pot further includes a burring portion 31, and the groove array extends to the burring portion. The groove array is distributed on the bottom and wall of the pot and also extends to the burring portion. Thus, no special positioning process is required for the composite metal sheet during manufacturing. The entire surface of the inner stainless steel layer is etched, engraved, or pressed to form the groove array, and then the pot blank is stretched to form the pot blank. The groove array is distributed on the bottom, wall, and burring portion of the pot.

[0056] The container further includes a seal ring 4, which covers the groove array extending to the burring portion, and the groove array extending to the burring portion forms a plurality of seal ring exhaust grooves. When the pot lid covers the pot body, the seal ring seals the gap between the pot lid and the pot. In this embodiment, the groove array in the burring portion and the seal ring combine to form the exhaust groove, which first opens to the outside when the lid is opened, preventing the seal ring from adhering to the pot.

[0057] The above are only specific embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Those skilled in the art can understand that the present invention includes, but is not limited to, the contents described in the drawings and the above specific embodiments. Any amendments that do not deviate from the functional and structural principles of the present invention fall within the scope of the claims. [Explanation of symbols]

[0058] 1. Pot body; 2...pot lid; 3 ···pot; 31 ···Burring section; 32...inner metal layer; 33 ···Soaking aluminum layer; 34 ···External stainless steel layer; 35...metal protective film; 36 ···ribs; 4 ···Sealing ring; 41 ···Sealing lip; 5 ···Groove; 6...Heating device.

Claims

1. An inner pot for a rice cooker including an internal metal layer, wherein the surface of the internal metal layer is provided with a plurality of mutually independent grooves, each having a depth of 0.04 to 0.15 mm; the internal metal layer is provided with a metal protective film, the thickness of the metal protective film within the grooves being 0.5% to 2% of the depth of the grooves; the metal protective film is coated on the internal metal layer by physical vapor deposition, and the thickness of the metal protective film is 0.5 μm to 2.5 μm.

2. 2. The inner pot of a rice cooker according to claim 1, wherein the thickness of the metal protective film is 0.5 μm to 2.5 μm.

3. 2. The inner pot of a rice cooker according to claim 1, wherein a support rib is provided between the grooves, and the width of the support rib is greater than the depth of the grooves.

4. 4. The inner pot of a rice cooker according to claim 3, wherein the width of the support rib is smaller than the width of the groove.

5. The inner pot of a rice cooker according to claim 3, wherein the roughness of the grooves is greater than the roughness of the support ribs.

6. The inner pot of a rice cooker according to claim 1, wherein the width of the groove is greater than the depth of the groove.

7. 2. The inner pot of a rice cooker according to claim 1, wherein the area in which the plurality of grooves are distributed covers more than two-thirds of the inner surface of the pot.

8. A cooking utensil comprising a pot body provided with an inner pot and a pot lid, wherein the inner pot is the inner pot of a rice cooking utensil described in any one of claims 1 to 7, a heating device is further provided within the pot body, and the area covered by the plurality of grooves is larger than the area covered by the heating device.

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