JPS6314968B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention forms a heating space around the outside of a pot, and heats the pot using radiant heat from a heater placed in this space and convection of heated air within the space. The present invention relates to a rice cooker of this type, and aims to improve the relationship between the pot bottom shape and heater arrangement in a large-scale rice cooker for commercial use, and to provide a rice cooker with less uneven cooking and good usability.

Traditionally, most large rice cookers for commercial use are gas-powered, and some of the 3.6-inch rice cookers are electric. An electric rice cooker has two methods: a pot is removably placed directly on top of a hot plate with an electric heater, and the heat from the electric heater is conducted from the hot plate to the bottom of the pot to cook rice; A method in which a space for heating is provided, a heater is placed in this space at a predetermined distance from the pot, and the pot is heated by radiant heat from the heater and convection of air within the space to cook rice. There is. In the former method, during the rice cooking process, the temperature difference between the top and bottom of the rice to be cooked tends to become large, resulting in the top being undercooked and loose with little moisture, and the bottom being heated too quickly, resulting in overcooking.
The disadvantage is that the rice is often cooked in a sticky state, and the cooking is uneven and the overall taste is poor.
Moreover, this tendency becomes stronger as the contact between the hot plate and the pot becomes more uneven, and as a large amount of rice is cooked for commercial purposes. When cooking a large amount of rice, the pot needs to be large, making it difficult to make uniform contact between the heating plate and the bottom of the pot, increasing production costs due to the need to strictly control dimensional accuracy, and requiring careful handling to prevent the pot from deforming. You need to be careful. The latter method has the advantage of being able to heat the pot from around the outside of the side of the pot, making it easier to achieve a relatively uniform cooked state, but the heat efficiency is lower than the former method, so it is necessary to increase the heater power. Because heat loss increases the temperature of the vessel,
Measures against the heat will become necessary. Furthermore, when using the latter method to cook a large amount of rice for commercial purposes, it is necessary to increase the heater power, so it is necessary to take sufficient heat countermeasures as described above. Gas rice cookers are often used as commercial rice cookers because they are easy to obtain a high amount of heat from the heat source, and because they are similar to the latter rice cooking method mentioned above, they have the advantage of making it easier to cook rice uniformly. is possible.

When the power of the heater is increased, the temperature of the heater rises, so in order to improve the durability of the heater, it is necessary to use a heater with a larger diameter and longer length to increase the effective heat generating area of the heater and lower the heater temperature. Furthermore, in order to cook a large amount of rice for commercial use, it is necessary to increase the electric power, and the pot also has a large shape and diameter, so it is necessary to consider the arrangement of the heater to suppress uneven cooking. In addition, since the pot tends to be handled roughly, it is necessary to have a structure that is particularly resistant to scratches, abrasion, and deformation, especially at the part that senses the pot temperature.

Due to the above reasons, gas rice cookers are the mainstream in the market as commercial rice cookers, but in the case of gas rice cookers, there is almost no heat for so-called re-cooking immediately after the rice is cooked, so Although it has the advantage that the temperature of the rice drops quickly after cooking and is difficult to burn, the rice did not have a delicious flavor, so there was a strong demand for deliciousness. In terms of usability, gas has a strong firepower, so the bottom of the pot is particularly thick to prevent uneven cooking, and in order to make the bottom of the pot thick, it is made of cast metal, making it heavy and difficult to handle. On the other hand, in recent years, the use of gas in some underground malls has been legally regulated in order to prevent disasters caused by gas leaks.
There is a growing demand for electric rice cookers for commercial use.

The present invention has been made in view of the above circumstances.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a cylindrical outer case, and metal fittings 2 are fixed to the upper inner surface of the case at two opposing locations.
Reference numeral 3 denotes an inner case, and the upper end opening has an edge protruding toward the outer circumference, and metal fittings 4 are provided on the lower outer circumferential side of the edge at four locations approximately equally spaced at the same time as spacers 5 are fastened on the inner circumferential side of the upper edge of the edge. It is fixed. The other outer end of the metal fitting 4 is locked to the upper end of the outer case 1, and the lower part is fastened to the metal fitting 2 at two opposing locations with screws. The spacer 5 has a slightly convex shape upwardly from the upper edge of the inner case 3, and the fastening part is formed in a concave shape so that the head of the fastening part does not protrude, and is made of a heat-resistant plastic material. 4 at intervals
are arranged. Reference numeral 6 denotes a pot having a flange portion with an opening upper end projecting outward, and the lower end of this flange is placed on a spacer 5 and is detachably housed in the inner case 3 in a suspended state. As a result, a heating space is formed continuously between the outer periphery of the side surface of the pot 6 and the lower part of the bottom. 7 is a pot 6 with a lid that has a knob 8
It is placed on the flange of the pot 6 to close the pot 6. 10
1 is a bottom plate having support legs 9, and has ventilation holes 39 formed in a plurality of places, and is fitted and fixed to the lower end of the outer case 1. The bottom of the inner case 3 is formed with substantially annular ribs 11a and 11b that are convex toward the inner surface, and a plurality of ventilation holes 12 are formed intermittently on the inner peripheral side of the ribs 11b. Said ribs 11a, 11b
A reflector 13 that reflects the heat of the heater toward the pan 6 is placed on the top surface, and is fixed to the bottom of the inner case 3 at the same time as the heater stand 14 is fixed. This reflector 1
The outer circumferential side of the case 3 extends upward in a substantially arc shape, and the outer circumferential diameter has a slight gap with the inner diameter of the inner case 3. The inner circumferential side is formed into a convex shape, and ventilation holes 15 are intermittent on the convex upper surface. Molded in multiple pieces. Heater stand 14 is L
It is formed into a letter shape and has four notches 16 at the upper end, and three sheathed heaters 1 are inserted into these notches 16.
7, 18, and 19 are placed, and heater press fittings 20, 21 are fixed to prevent the sheathed heater from coming off upward. To fix this heater stand 14, one of the mounting parts is formed into a crank shape, and the rib 1 at the bottom of the inner case 3 is
The rib 1a is inserted through and locked into a hole provided on the upper surface, and the other end is fixed to a pot hole on the upper surface of the rib 11b with a screw through a reflector 13. Further, the holes in the reflector 13 on the crank-shaped molded side of the heater stand 14 and the holes on the upper surface of the rib 11a are made large in diameter in anticipation of an expansion margin in order to release thermal expansion of the heater stand 14 due to heater energization.
The cross-sectional shape of the bottom of the pot 6 is a substantially spherical cross-section with a convex inner surface, and the distance between the three heaters and the bottom of the pot 6 is about the same as that of the sheathed heater 17 with respect to the cross-sectional shape of the pot bottom.
is located above the other two heaters 18 and 19, and the distance between the outer circumferential side of the heater 17 and the heater 18 is larger than the other heater pitches. The outermost heater 19 is disposed below the lowest part of the pot 6, and the heaters 18 and 19 are located on the same plane, so the distance between the heater 18 and the bottom of the pot is larger than that of the heater 19. A heat-sensitive device 22 that senses the pot temperature and controls rice cooking is disposed at the center of the bottom of the pot 6, and around it is a heat-sensitive device outer case 23 and a heat shield ring 2 to avoid heat influence from the heating space.
4. A heat shield cylinder 25 is provided. Heat shield ring 2
4 is a plate made of aluminum fabric formed into a cylindrical shape with a concave cross section.
3 and the heat-sensitive device sliding plate 26, the heat-sensitive device sliding plate 26 is fitted between the two. In addition, the heat-sensitive device sliding plate 26 has three tabs 27 protruding downward at approximately equal intervals, and the tabs 2 are inserted into the tab through-holes formed in the heat-sensitive device fixing plate 28 fixed to the center of the bottom of the inner case 3.
It is inserted and locked by bending 7. A tab also protrudes downward from the bottom of the heat sensitive device 22, and is inserted and locked into a tab through hole formed in the heat sensitive device sliding plate by bending the tab. 29 is a coil spring that always biases the heat sensitive device upward; 30 is a coil spring that always biases the heat shield ring 24, the heat sensitive device outer case 23, and the heat sensitive device sliding plate 26 upward; It has great power. A lever 31 transmits the rice cooking control operation of the heat sensitive device 22 to the micro switch 32, and is rotatably mounted on a bearing 35 of a frame 34 attached to a mounting plate 33 fixed to the outer case 1. . 36 is a rice cooking button for starting rice cooking.

Next, the operation of this embodiment configured as above will be explained. The outer case 1 and the inner case 3 are fastened and fixed together with the spacer 5 through a metal fitting 4 fixed to the inner case 3 and a metal fitting 2 fixed to the outer case 1 with screws. Washed rice 37 and water 38 necessary for cooking the rice 37 are stored in a pot 6, and the pot 6 is stored in an inner case 3. At this time, the pot 6 is guided by the spacer 5 fixed to the upper part of the inner case 3 and positioned approximately at the center of the inner case 3, and the flange of the pot 6 is placed on the upper surface of the spacer 5 formed of heat-resistant plastic. The pot 6 is housed in the inner case 3 in a suspended state to form a space for heating, and the heating space around the outer periphery of the side surface of the pot 6 is formed substantially uniformly. Also spacer 5
protrudes from the upper end surface of the inner case 3, so a gap is formed between the flange portion of the pot 6 and the upper end surface of the inner case 3, and the heating space is communicated with the outside, and the flange portion of the pot 6 is connected to the inner case 3. 3. Metal-to-metal contact is avoided because the upper opening edge is not directly contacted. Further, since the fastening parts of the spacer 5 are also housed within the spacer 5, the side surface of the pot 6 will not be damaged. When the pot 6 is stored in the inner case 3, the heat-sensitive device 22 disposed at the center of the bottom of the inner case 3 is pushed down and pressed against the bottom of the pot 6.
Since the coil spring 30 that biases the heat shield ring upward has a stronger spring force than the coil spring 29 that biases the At the same time, it prevents hot air in the heated space from entering into the heat sensitive device 22 side.
It plays a role of actively transmitting the heat received by the heat shield ring 24 to the vicinity of the bottom center of the pot 6. Pot 6 is inside case 3
While it is stored in the pan, hold the lid 7 by the knob 8 and open the pot 6.
When the rice cooker button 36 is pressed down, the lever 31 is rotated around the bearing 35 of the frame 34 and held by the heat sensitive device 22, and the micro switch 32 is closed and the sheathed heaters 17, 18, 1 are closed.
9 is energized and generates heat. Due to the heat generated by the heater, the diameter of the heater increases due to thermal expansion, and the heater moves outward from the notch 16 of the heater stand 14. The heater stand 14 also expands due to thermal expansion, but it can expand without any problem due to the relief of the crank-shaped locking portion formed on the outside.
As the electricity passes, the heating space is heated and the pot 6
The contents are heated and cooking progresses. At this time, air flows in from the outside into the lower center of the heating space through the ventilation hole 12 provided at the bottom of the inner case 3 and the ventilation hole 15 of the reflector that communicates with the ventilation hole 12, and this inflow air is heated by the heater and becomes a high-temperature airflow. The liquid then flows out from the gap between the flange portion of the pot 6 and the upper opening edge of the inner case 3 via the outer periphery of the side surface of the pot 6. At this time, the sides of the pot 6 are efficiently heated and the upper part of the contents also begins to cook, and the temperature begins to rise relatively early.The center of the pot 6 also has a high heat reflectivity pressed against the bottom of the pot, and has a high thermal conductivity. By arranging the high heat shielding ring 24, the inner circumferential side of the sheathed heater 17 is curved to a small diameter, so that the heat transfer to the center of the pot 6 can be increased, and the spacing between the heaters is the same as that between the outer circumferential side of the heater 17 and the heater 18. Since the gap between the heater 18 and the bottom of the pot is larger than the others, and the distance between the heater 18 and the bottom of the pot is also larger than the others, uneven cooking is suppressed around the outer periphery of the heater 17 and around the heater 18, where the temperature of the heating space is most likely to become high. ing. As the rice cooking progresses, the air around the outside of the inner case 3 is also heated, and this heated air becomes an upward airflow and flows out through the gap between the upper opening edge of the inner case 3 and the upper opening of the outer case 1. As the cooking progresses, the water in the pot 6 decreases, and the bottom of the pot 6 becomes in a state close to a so-called dry baking state, and the temperature rises rapidly. The temperature at this time is pot 6
The temperature sensing device 22 pressed against the bottom senses the temperature, releases the adsorption of the lever 31 at a predetermined temperature, pushes down the lever 31, closes the micro switch 32, and cuts off the power to the sheathed heaters 17, 18, 19. Even after the cross-section, convection continues in the heating space due to the high temperature, and outside air continues to flow in through the vent hole 12 provided at the bottom of the inner case 3 and the reflector 15. This inflow of outside air serves to suppress the progress of the so-called dry baking state at the bottom of the pot 6 and prevent it from burning. Also, heat shield ring 24
This arrangement allows the heat-sensitive device 22 to operate at a low temperature, which has the advantage of preventing scorching. Reflector 13
The purpose of this is to reflect the heat of the sheathed heater upward.The spaces 37 and 38 formed between the bottom of the inner case 3 of the reflector 13 enhance the heat insulation effect and increase the thermal efficiency, and at the same time, the outer periphery of the inner case 3 and the outer The temperature rise in the space formed by the case 1 can be suppressed.

As shown in FIG.
is formed into a double winding, and the other heater is formed into a substantially annular single winding. This allows the development lengths of the three heaters to be made close to each other, and most commercial applications use 200V class power supplies, reducing the unbalance rate of the power supply equipment when using three-phase power supplies. In addition to being able to reduce the number of heaters, it is also cheaper in terms of cost and the heater temperature can be brought closer.
You can reduce uneven cooking and shorten the lifespan of the heater.

As is clear from the above description, according to the structure of the present invention, the cross-sectional shape of the pot bottom is made convex toward the inside of the pot, thereby increasing the rigidity of the pot bottom, thereby making the pot thinner and lighter in weight. When taking the pot out of the inner case and placing it on another table, the bottom of the pot is stable because the outer periphery touches it, and the center part where the heat-sensitive device is pressed is separated from the table on which it is placed, so there is no chance of scratches. This has the advantage of having a structure that is resistant to wear. In addition, the heaters are arranged in a step-like manner along the cross-sectional shape of the bottom of the pot, and the spacing between the heaters is such that the space around the heaters tends to reach the highest temperature in the middle of multiple heaters in parallel, and the outermost heaters are arranged in a stepped manner. By locating it below the lowest part of the pot bottom, the outer periphery of the pot can be efficiently heated, and the bottom surface of the pot can be easily heated evenly, which has the advantage of providing a rice cooker with less uneven cooking.

[Brief explanation of the drawing]

FIG. 1 is a front longitudinal sectional view of a commercial rice cooker showing one embodiment of the present invention, FIG. 2 is a plan view of the main body with the pot removed, and FIG. 3 is a sectional view of the main parts. 1... Outer case, 3... Inner case, 6... Pot,
17, 18, 19... Sheathed heater.

Claims (1)

[Scope of Claims] 1. An inner case having a bottomed cylindrical shape with an open upper surface and an edge in the outer circumferential direction inside the outer case, and a flange portion whose upper end protrudes toward the outer circumferential direction. a pot that is placed on the upper edge of the inner case so as to be removably housed with its bottom floating above the bottom of the inner case, forming a predetermined space between the pot and the inner case; This pot has a cross-sectional shape with an upwardly convex pot bottom, and heaters are arranged at predetermined intervals to correspond to the pot bottom shape. 2. The rice cooker according to claim 1, wherein the heater is ring-shaped and one or more heaters are arranged in a stepped manner corresponding to the cross-sectional shape of the bottom of the pot. 3. The rice cooker according to claim 1, wherein the outermost heater is located below the lowest part of the pot bottom. 4. The rice cooker according to claim 1, wherein the distance between the parallel heaters is larger than the distance between the heaters on the outer circumferential side and the distance between the heaters on the center side.