JP3620516B2 - Cooking pot and method of manufacturing the pot - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooking pan that prevents the occurrence of an unsafe state such as overburning or ignition of a cooked food by providing a self-temperature control function in a non-metallic pan, and a method for manufacturing the same. In particular, the present invention relates to a cooking pan suitable for induction heating.
[0002]
[Prior art]
As heat sources for cooking these days, gas, electric heaters, microwave heating, induction heating, etc. have been diversified, but in recent years, induction heating cookers understand their excellent features such as safety, ease of use, and high thermal efficiency. It has been widely spread to general households. 200V compatible models have also been developed and are generally understood in terms of high thermal power.
[0003]
As shown in FIG. 3, the induction heating cooker is an object to be heated placed on the top plate (high-frequency magnetic flux generated by applying a high-frequency current to the heating coil 12 disposed below the top plate 11 ( An eddy current is generated in the pan), and the pan is controlled by the control device 14 so that the pan itself generates heat directly.
[0004]
In addition, a temperature sensor 15 for detecting the temperature of the pan is also standardly provided at the lower part of the top plate of the induction heating cooker, so that an “overtemperature prevention function” for controlling the heating state according to the detected temperature can be provided. It can be used safely.
[0005]
However, recent induction cookers have high thermal power, so the food is likely to burn, or when cooking with a small amount of oil, it may be heated to near the ignition temperature of the oil, and further safety is required. Has been.
[0006]
Therefore, in recent years, as disclosed in Japanese Patent No. 2917526 and Japanese Patent No. 3079573, a metal having a Curie point near the temperature used for actual cooking (hereinafter referred to as “temperature-sensitive metal”) is used as a metal for a pan. It has been proposed to use. Since metal loses its magnetism above the Curie point, it is characterized by not being heated by induction heating. Taking advantage of this feature, pans where the temperature of the pan itself is not heated above the Curie point are also being investigated.
[0007]
Although it is the induction heating cooking appliance which has the outstanding characteristic in this way, the subject that the cooking appliance made from ceramics, such as a clay pot and a glass pot, cannot be used on the characteristic of the heating method. In order to deal with such problems, for example, a pan capable of induction heating has been proposed by forming a silver thin film 17 on the bottom surface of a clay pan 16 as shown in FIG. However, when the base material of the pan is ceramic, heat conduction is poor compared to metal, so that the heat induced by the thin film is not easily transmitted to the entire pan, so that the temperature of the heat generating part tends to rise. It was. This problem was prominent when the pan was baked, and the phenomenon of disconnection and peeling of the heat generation layer was likely to occur.
[0008]
Further, in such a configuration, the heat of the heat generating part is radiated and conducted to the induction heating cooker main body, particularly the top plate 11, the temperature sensor 15, the heating coil 12, the control device 14, etc., and the temperature of each part rises. There was also a problem that it was easy.
[0009]
In some cases, even in the normal cooking state, the temperature rise of the temperature sensor 15 becomes large, and the over-rise prevention function (OHP function) may operate. Therefore, as an actual product, the shape of the back surface is uneven so that only the heat generating part is separated from the top plate, and there is a problem in workability and careability.
[0010]
In addition, in the thermal shock test that assumes a state in which abnormal heating is performed in such a configuration and water is added, it is necessary to set the temperature difference large, so that the temperature difference can be endured. For example, in the case of clay pots, raw materials that have a very small thermal expansion are used, which increases the cost.
[0011]
[Problems to be solved by the invention]
The present invention solves such a conventional problem. When heating a non-metallic pot such as an earthen pot or a glass pot, the heating plate has a self-temperature control function in the case of abnormal heating. The object is to provide a cooking pan that ensures safety by preventing the temperature from rising above the temperature.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the present invention forms a nonmagnetic metal layer on a lower surface of a cooking vessel made of a nonmetallic material by spraying so as to have a thickness of 2 mm or more. A magnetic metal layer having a Curie temperature of not less than 0.3 mm and a thickness of 0.3 to 2.5 mm, which is not less than the penetration depth of the eddy current below the Curie temperature and not more than the penetration depth above the Curie temperature. By forming by thermal spraying, even a non-metallic pan has a self-temperature control function, which prevents the temperature from rising during baking and the exfoliation / disconnection of the heating element.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, a nonmagnetic metal layer is formed on the lower surface of a cooking vessel made of a nonmetallic material by thermal spraying so as to have a thickness of 2 mm or more , and further, a predetermined Curie temperature is formed on the lower surface. A magnetic metal layer having a thickness of 0.3 to 2.5 mm is formed by thermal spraying so as to have a thickness in the range of 0.3 to 2.5 mm, which is not less than the penetration depth of eddy current below the Curie temperature and below the penetration depth above the Curie temperature. By doing so, since the self-temperature control function can be provided, it is possible to prevent the occurrence of an unsafe state such as overburning or ignition of the food.
[0014]
As a means for providing the self-temperature control function, there is a method of detecting the magnetic change of the pan on the heating cooker side and controlling the heating power accordingly. For example, a magnet type switch is placed in contact with the bottom of the pan, and if the pan is below the Curie temperature, the magnet is attracted to the pan bottom. . By controlling the heating power and power supply to the cooking device in conjunction with the movement, self-temperature control at the Curie temperature can be realized.
[0015]
Heating the pan directly by induction heating is simpler. When the pan temperature rises to the Curie temperature, the temperature-sensitive metal layer loses magnetism, and the magnetic field lines flow to the nonmagnetic metal layer above it. Since the layer has a low skin resistance, it does not generate heat, and as a result, it cannot be raised above that temperature. In this case, since no means for detecting the temperature of the pan is necessary, a very simple configuration can be achieved as a cooking device.
[0016]
Furthermore, since the bottom surface does not rise above a certain temperature, for example, in the case of a pan for an induction heating cooker, the temperature rise of the induction heating cooker body, especially the top plate, temperature sensor, heating coil, and control device, facing the heat generating part Can be held down, and the level of the cooling structure that has been necessary in the past can also be held down. In addition, since the malfunction of the over-temperature prevention function (OHP function), which has been a problem in the past, can be suppressed, the adverse effects on actual cooking due to malfunction are reduced, and the shape of the back surface is made as flat as possible to improve workability. Care can be improved.
[0017]
In addition, a metal used as a temperature-sensitive metal such as an Fe—Ni alloy has a very small coefficient of thermal expansion as compared with silver or the like conventionally used as a heating element, so that heat with ceramics or the like as a base material can be reduced. The expansion difference is also reduced, and warping and deformation of the bottom surface can be reduced. Accordingly, exfoliation and disconnection of the heat generation layer can be reduced.
[0018]
Furthermore, since the temperature rise of the pan itself can be set to a predetermined temperature, the temperature difference becomes small even for a thermal shock that is poured into water from the maximum temperature during heating. Therefore, as a material of the cooking container body, for example, in the case of an earthenware pot, a general raw material can be used as an earthenware pot that has a larger coefficient of thermal expansion than the conventional example but is inexpensive in terms of cost.
[0019]
According to the second aspect of the present invention, a nonmagnetic metal layer or a temperature sensitive metal layer whose corrosion resistance is reduced by thermal spraying can be protected from corrosion by providing a protective layer made of a magnetically permeable material on the lower surface of the magnetic metal layer. Therefore, even if it is used in a kitchen where a highly corrosive seasoning such as salt, soy sauce or vinegar adheres, it can be used satisfactorily without causing corrosion or the like. In general, such a protective layer is often formed by painting, and for example, a silicone-based heat-resistant paint is used.
[0020]
The invention according to claim 3, the magnetic metal having a plurality of different Curie temperature, each adjusted spraying amount so that any ratio by spraying simultaneously sprayed layer in a predetermined self-system A temperature control function can be provided. In particular, the composition of the temperature-sensitive metal layer formed as the sprayed layer can be arbitrarily adjusted by adjusting the spraying amount of each temperature-sensitive metal during spraying, so that the self-control temperature of the temperature-sensitive metal layer is also arbitrarily set. It is a pan that can be set in detail. On the other hand, it is not necessary to have many kinds of raw materials for the thermosensitive metal, which is very advantageous in terms of mass productivity and cost.
[0021]
According to a fourth aspect of the present invention, a nonmagnetic metal layer is formed on a lower surface of a pan made of a nonmetallic material by thermal spraying so as to have a thickness of 2 mm or more, and a plurality of different curie are formed on the lower surface. The amount of spraying of the magnetic metal having a temperature is adjusted so that it becomes an arbitrary ratio in the sprayed layer, and the penetration depth is not less than the penetration depth of the eddy current below the Curie temperature and below the penetration depth above the Curie temperature. Since the self-temperature control function can be imparted by spraying simultaneously so as to have a thickness in the range of 0.3 to 2.5 mm, it is possible to prevent the occurrence of unsafe conditions such as overburning of the food and ignition. Furthermore, the self-control temperature of the temperature-sensitive metal layer can be set arbitrarily finely.
[0022]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking as an example a clay pot that can also perform induction heating.
[0023]
(Example 1)
1 is a cross-sectional view of a main part of a cooking pan and an induction heating cooker showing Embodiment 1 of the present invention. 1 is a ceramic cooking vessel, and this time, a clay pot made of a base material mixed with 35% of petalite (Li2O.Al2O3.8SiO2) was used. Provided a non-magnetic metal layer 2 on the entire rear surface of the cooking container 1 made of a thermal good-conductive aluminum by arc spraying method, a temperature-sensitive metal made further from the lower surface 36% Ni-Fe alloy, use of nitrogen gas A temperature-sensitive metal layer was formed on the entire back surface in the same manner as aluminum by arc spraying in an inert atmosphere. Here, the thickness of the aluminum sprayed layer was 2.5 mm, and the thickness of the temperature-sensitive metal sprayed layer was 0.5 mm. In addition, the shape of the bottom surface was flat.
[0024]
The cooking pan thus prepared was heated by an induction heating cooker having the top plate 4, the temperature sensor 5, the heating coil 6 and the control device 7 as main components.
[0025]
Although it was first heated in an baked state, the temperature at the bottom did not rise above about 250 ° C., and there was no particular abnormality in the exfoliation / disconnection of the heating part and the appearance of the pan, and it could be used safely thereafter.
[0026]
Moreover, although water cooking was performed as actual cooking, even in this, cooking was possible without practical problems such as malfunction of the OHP function. In particular, in conventional earthenware pans for induction heating cookers, carbohydrate-based ingredients such as rice cakes and udon were easy to scorch on the bottom surface, but such a phenomenon did not occur.
[0027]
In addition, as a material for clay pots, a material based on petalite, which has low thermal expansion, was used as a main component. However, the material is not limited to this, and a material composed of general ceramic materials such as materials based on clay or kaolin. May be used.
[0028]
Moreover, although aluminum was used as the nonmagnetic metal, copper or other nonmagnetic metals may be used. In addition, although the thickness of aluminum which is a nonmagnetic metal layer is 2.5 mm, in order to have a self-temperature control function, it may be 0.1 mm or more which is a thickness that does not generate heat due to eddy current in aluminum. However, from the standpoint of heat uniformity, if it is 1 mm or more, there is no practical problem, and if it is 2 mm or more, it is very good. On the other hand, the thickness of the temperature-sensitive metal layer is set to 0.5 mm, but it may be greater than the penetration depth of eddy current below the Curie temperature and below the penetration depth above the Curie temperature, specifically about 0. .3 mm to 2.5 mm is preferable.
[0029]
In addition, although a 36% Ni-Fe alloy was used as the temperature sensitive metal, it is not limited to this, and the Curie temperature of the sprayed layer is 100 ° C. or higher which is the boiling point of water, and 370 ° C. or lower which is the ignition point of oil. If it is the composition which becomes, it acts effectively. Practically, a range of 120 ° C. to 350 ° C. with a margin for these temperatures is desirable. Moreover, for the main application of stewed cooking like a pot, if it sets to 120 to 200 degreeC, a cooked product will not burn too much and a product with much higher added value can be provided.
[0030]
The thermal spraying is performed in an inert atmosphere, but the present invention is not limited to this, and thermal spraying may be performed in a normal atmosphere. However, in that case, since the sprayed material is oxidized, the Curie temperature of the sprayed layer tends to be higher than the Curie temperature of the material. For this reason, it is preferable to perform thermal spraying in the above-described inert atmosphere or to blend a material that is more easily oxidized than a constituent of the thermal spray material to be used, for example, a so-called oxygen scavenger such as silicon or manganese. Moreover, you may use the temperature-sensitive metal raw material which has a Curie point higher than desired temperature.
[0031]
(Example 2)
FIG. 2 is a cross-sectional view of the main part of the cooking pan and the induction heating cooker showing Embodiment 2 of the present invention. The basic configuration is the same as in Example 1, but a protective layer 8 made of a silicone-based inorganic heat-resistant paint is provided on the lower surface of the magnetic metal layer.
[0032]
An experiment was conducted in which the cooking pan A thus prepared and the cooking pan B having the same configuration and without a protective layer were immersed in a washing bowl containing miso soup for a long time. Cooking pan B was immersed overnight, and red rust was generated on the bottom of the pan, and practical problems were observed. However, even with cooking pan A 3 Hitachi, no noticeable red rust occurred. It was a level where there was no problem in practical use.
[0033]
(Example 3)
In producing the cooking pan in Example 1, when forming the temperature-sensitive metal layer, the same 36% Ni—Fe alloy and 30% Ni—Fe alloy as in Example 1 (Curie temperature: about 100 ° C.) Were simultaneously sprayed at a ratio of 1: 2.
[0034]
A test similar to Example 1 was conducted using the cooking pan thus prepared. The bottom surface temperature during baking was about 150 ° C., and exhibited a desired self-temperature control function according to the Curie temperature of the temperature-sensitive metal used for thermal spraying and its blending ratio. In addition, in the water cooking test, rice cakes and udon were cooked well without sticking to the bottom.
[0035]
As is apparent from this example, a cooking pan having a self-temperature control function at various temperatures can be obtained by spraying a temperature-sensitive metal having a predetermined Curie temperature at an arbitrary ratio.
[0036]
In any of the embodiments, a more practical pot can be provided by forming a coating layer for rust prevention on the outermost layer surface on the bottom surface of the pot bottom.
[0037]
In any of the embodiments, the induction heating cooker is used as a heating device. However, the present invention is not limited to this, and the heating cooker using a gas or an electric heater as a heat source includes a means for detecting the magnetic change in the pan. If it is, the same effect can be acquired.
[0038]
Moreover, although the earthenware pot was demonstrated as an example of the raw material of a cooking container, the same effect can be acquired if it is non-metallic materials, such as general ceramics including glass etc., resin, and water-resistant paper.
[0039]
【The invention's effect】
As described above, according to the inventions described in claims 1 to 4 , it is possible to provide a cooking pan that has safety by ensuring that it has a self-temperature control function and does not rise to a predetermined temperature abnormality even when it is abnormal. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a cooking pot and induction heating cooker showing first and third embodiments of the present invention. FIG. 2 is a cooking pot and induction heating cooking showing a second embodiment of the present invention. Cross-sectional view of the main part of the vessel [Figure 3] Cross-sectional view of the main part of the induction heating cooker body and the conventional earthenware pot for induction heating cooker
DESCRIPTION OF SYMBOLS 1 Cooking container 2 Nonmagnetic metal layer 3 Magnetic metal layer 6 Heating coil 7 Protective layer

Claims (4)

The lower surface of the cooking container made of a non-metallic material, sprayed by forming a non-magnetic metal layer to a thickness of more than 2 mm, further the Curie magnetic metal layer having a predetermined Curie temperature on its lower surface A cooking pan formed by thermal spraying so as to have a thickness in the range of 0.3 to 2.5 mm, which is not less than the penetration depth of eddy current below the temperature and not more than the penetration depth above the Curie temperature . The cooking pan according to claim 1, wherein a protective layer made of a magnetically permeable material is provided outside the magnetic metal layer. A plurality of magnetic metal having a different Curie temperatures, each by spraying simultaneously by adjusting the spraying amount so that the arbitrary ratio in the sprayed layer, according to claim 1 or with a self-temperature control function of a predetermined temperature 2. The cooking pot according to 2. A non-magnetic metal layer is formed on the lower surface of a pan made of a non-metallic material by thermal spraying so as to have a thickness of 2 mm or more , and a magnetic metal having a plurality of different Curie temperatures is further sprayed on the lower surface. The spraying amount is adjusted to an arbitrary ratio in the layer , and the range is 0.3 to 2.5 mm which is not less than the penetration depth of the eddy current below the Curie temperature and below the penetration depth above the Curie temperature. The manufacturing method of the pan which sprays each simultaneously so that it may become the thickness of .

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