JPS6337651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention forms a heating space around the outer periphery of a pot, and heats the pot using radiant heat from a plurality of heaters disposed within the space and convection of heated air within the space. This invention relates to a rice cooker that uses a heating method, and aims to provide a rice cooker that can reduce uneven cooking when cooking a large amount of rice by setting a time difference in the start of energization of multiple heaters, especially in large-scale rice cookers such as those for commercial use. It is something.

Traditionally, most commercial rice cookers with a rice cooking capacity of about 3.6 to 6 are gas-type, and some electric rice cookers with a rice cooking capacity of about 3.6 are found in small-sized rice cookers for commercial use. It is the extent that it can be done. When cooking a large amount of rice, such as for commercial use, the pot is large and the rice layer is deep, so a high amount of heat is required as a heating source.The best way to cook rice is to heat it from the entire periphery of the pot. However, in the case of a gas type, the gas-fired heated air surrounds the pot, and a large amount of heat is absorbed from the sides of the pot. This is thought to be the reason why gas-type rice cookers are widely used as large-scale rice cookers for commercial use because the temperature starts to rise. However, since the high-temperature gas combustion flame directly heats the bottom of the pot, the parts that are hit by the gas combustion flame heat up rapidly, and because they are constantly exposed to the high-temperature flame during cooking, the rice becomes overheated and becomes sticky. This has the disadvantage that the overall taste is poor. In addition, as a way to alleviate the concentrated heating caused by this combustion flame and reduce the sticky state, it was proposed to make the bottom of the pot very thick, around 10 mm, but this did not solve the sticky state. It is not possible to create a pattern on the pot due to its thick wall.
It is made by casting and has relatively thick walls other than the bottom of the pot.It has a rice cooking capacity of class 6 and the weight of the pot alone exceeds 4 kg, making it extremely heavy, difficult to use, and expensive to process. It is. In addition, in the case of a gas rice cooker, after the rice has been cooked and the fire has been extinguished, there is almost no heat as a so-called re-cooking effect, so the temperature of the cooked rice drops quickly, and there is no advantage in preventing the cooked rice from burning at the bottom of the pot. However, the steaming effect was weak and the rice was watery, and the rice was not delicious and flavorful.

The present invention was invented in view of the above circumstances, taking advantage of the advantage of the electric method that it is easy to control the amount of heat used for cooking rice.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 opening has an edge protruding toward the outer circumference, and metal fittings 4 are installed on the lower outer circumference side of the edge at four locations approximately equally spaced at the same time as spacers 5 are fastened on the inner circumference side of the upper end 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 pressed pot with a wall thickness of 2 mm having a flange portion with the upper end of the opening protruding outward, and the lower end of this flange is placed on a spacer 5 and stored in a suspended state in the inner case 3 in a detachable manner. has been done. 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. A lid 7 has a knob 8 and is placed on the flange of the pot 6 to close the pot 6. Reference numeral 10 denotes a bottom plate having support legs 9, which 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 has a substantially annular rib 11 that is convex on the inner surface.
a, 11b are molded, and a plurality of ventilation holes 12 are formed intermittently on the inner peripheral side of the rib 11b. A reflector 13 for reflecting the heat of the heater toward the pan 6 is mounted on the upper surface of the ribs 11a, 11b, and is fixed to the bottom of the inner case 3 at the same time as the heater stand 14 is fixed. The outer circumferential side of this reflector 13 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 a ventilation hole 15 is formed on the convex upper surface. Multiple pieces are molded intermittently. The heater stand 14 is formed into an L-shape and has four notches 16 at its upper end.
Three sheathed heaters, two inner circumferential heaters 17 and 18 and one outer circumferential heater 19, are placed on 6.
Heater holding fittings 20 and 21 are fixed to prevent the sheathed heater from coming off upward. The heater stand 14 is fixed by molding one of the mounting parts into a crank shape and inserting and locking it into a hole provided on the upper surface of the rib 11a at the bottom of the inner case 3, and attaching the other part to a pot hole on the upper surface of the rib 11b with a screw to attach the reflector 14. It is fixed through. Further, the holes in the reflector 13 on the crank-shaped side of the heater stand 14 and the holes on the upper surface of the rib 11a are made large in diameter to allow for expansion 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 concave inner surface, and the distance between the three heaters and the bottom of the pot 6 is the same as that of the inner circumferential heater formed in a double wrap with respect to the cross-sectional shape of the pot bottom. 17 is the other two heaters 18,1
9, and the distance between the outer circumferential side of the heater 17 and the heater 18 is larger than that of the other heater pitches. The outer peripheral heater 19 is disposed below the lowest part of the pot 6, and since the heaters 18 and 19 are located on the same plane, 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 surrounding it are a heat-sensitive device outer case 23, a heat shield ring 24, and a heat shield ring 24 to avoid heat influence from the heating space. A heat shield cylinder 25 is provided. The heat shielding ring 24 is made by molding a plate of aluminum material into a cylindrical shape with a U-shaped cross section, and is fitted between the bottomed cylindrical outer case 23 of the heat sensitive device and the heat sensitive device sliding plate 26 by fixing them together. It is worn. Further, the heat-sensitive device sliding plate 26 has three claws 27 protruding from the bottom at approximately equal intervals, and the inner case 3
A tab 27 is bent and inserted into a tab through hole formed in a heat sensitive device fixing plate 28 fixed to the center of the bottom. 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 an operation plate 33 fixed to the outer case 1. 36 is a rice cooking button for starting rice cooking. Reference numeral 40 denotes a case for storing electrical components, etc., and a plate 41 for shielding radiant heat from the heater side and water infiltration is fixed with a gap. 4
2 is a circuit board having a timer function for controlling energization of the inner peripheral heaters 17 and 18, and a relay 43 is disposed thereon.

Next, the operation of this embodiment configured as above will be explained. The outer case 1 and the inner case 3 are fastened together with a spacer 5, a metal fitting 4 fixed to the inner case 3, and a metal fitting 2 fixed to the outer case 1 using 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 a 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 formed by the spacer 5 made of heat-resistant plastic.
It is placed on the upper surface of the pot 6 and stored in the inner case 3 in a suspended state, and a space for heating is formed, and the heating space on the outer periphery of the side surface of the pot 6 is formed substantially uniformly. Further, since the spacer 5 protrudes from the upper end surface of the inner case 3, 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. Metals do not come into direct contact with the upper opening edge of the inner case 3, thereby avoiding metal-on-metal contact. 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.
By storing the pot 6 in the inner case 3, the inner case 3
The heat-sensitive device 22 disposed at the center of the bottom of the pan 6 is pushed down as the pan 6 is stored, and is pressed against the bottom of the pan 6.
Coil spring 2 biasing the heat sensitive device 22 upward
Since the coil spring 30 that biases the heat shield ring upward has a stronger spring force than the coil spring 9, the heat shield ring 2
The upper opening edge of 4 is similarly pressed against the bottom of the pot 6 to prevent hot air from the heating space from entering the heat sensitive device 22 side, and at the same time actively directs the heat received by the heat shielding ring 24 to the vicinity of the center of the bottom of the pot 6. It serves the purpose of communicating. pot 6
is stored in the inner case 3, and then turn the lid 7 with the knob 8.
When the rice cooker button 36 is pushed down, the lever 31 is rotated around the bearing 35 of the frame 34 and held by the heat-sensitive device 22, which closes the micro switch 32 and starts the heating process. When the outer peripheral heater 19 is energized, the timer function of the circuit board 42 starts. As the outer peripheral heater 19 is energized, the temperature of the heating space rises and heats the outside of the pot. Since the outer peripheral heater 19 is disposed below the lowest part of the outer periphery of the pot bottom in an arc shape with a small curvature, the temperature of the pot bottom around the sheathed heater 19 does not rise rapidly, and the heated air becomes an upward air current. The outer periphery of the side surface of the pot can be heated from the early stage of the rice cooking process, and the effect of bringing the temperature rise at the top of the rice to be cooked closer to the temperature rise at the bottom of the pot to be cooked can be obtained. Furthermore, when electricity is being supplied only by the outer sheathed heater 19, the temperature around the bottom of the pot near the inner heaters 17 and 18 also rises in the lower part of the heating space, so the temperature rises gradually and promotes moisture absorption in the rice. , the thermal conductivity of the rice can be increased, and the heat received by energization of the inner peripheral heaters 17 and 18 can be efficiently transferred to the upper part. The time for energizing only the outer heater 19 is set by adjusting the constants of the elements of the timer function circuit so that the relay 43 is activated and the inner heaters 17 and 18 are energized during the heating process in which the rice reaches the gelatinization temperature. It is set by In this way, the inner circumferential heaters 17 and 18 are energized from the middle of the heating process of rice cooking, and as the energization progresses, the temperature in the heating space further rises, and the high temperature air around the heaters is disposed at the bottom of the inner case 3. The air around the outside of the inner case 3 flows into the lower part of the heat shielding ring 24, which serves as a heat shield for the heat-sensitive device 22 at the center of the lower part of the heating space, through the vent hole 12 of the reflector that communicates with the vent hole 15 of the reflector. It 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. As a result, the heating of the rice to be cooked from the side of the pot is further promoted, and the upper part of the rice to be cooked is heated by convection between the center of the pot 6 and the periphery of the water 38.
The upper part of the center of the pot 6 is also heated. FIG. 4 graphically shows the effects described above. Figure 4a shows the temperature changes at points A and B when three sheathed heaters 17, 18, and 19 are energized at the same time from the beginning of the heating process.
The temperature difference between point B is large, and as soon as the temperature at point B reaches 100°C, the power is cut off.The upper part of the pot is hard due to insufficient cooking and absorbs little water, while the bottom of the pot is soft and cooks unevenly. On the other hand, in this example, as shown in Fig. 4b, the temperature difference between points A and B is small, and point B can be maintained at 100°C for a long time, and the temperature at the bottom of the pot does not rise rapidly either. As a result, uneven cooking can be minimized overall.

As the cooking progresses, the water in the pot 6 decreases due to water absorption and evaporation of the rice, and the bottom of the pot 6 becomes almost in a so-called dry baking state, and the temperature rises rapidly. The temperature sensing device 22 pressed against the bottom of the pot 6 senses this temperature change, releases the adsorption of the lever 31 at a predetermined temperature, pushes down the lever 31 and opens the micro switch 32, and the sheathed heaters 17, 18, 19 is disconnected.
Even after the power is cut off, convection continues in the heating space due to the high temperature, and the ventilation hole 12 provided at the bottom of the inner case 3
The outside air continues to flow in through the reflector 15 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. Further, by providing the heat shielding ring 24, the heat sensitive device 22 can be operated at a low temperature, which has the advantage of preventing scorching. The reflector 13 reflects the heat of the sheathed heater upward, and the spaces 37 and 38 formed between the reflector 13 and the bottom of the inner case 3 enhance the heat insulation effect and increase the thermal efficiency.
The temperature rise in the space formed by the outer periphery and the outer case 1 can be suppressed.

Further, as shown in FIG. 2, the heater 17 is formed into a double winding, and the other heaters are 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, making it possible to reduce the unbalance rate of power supply equipment when using three-phase power supplies. . In addition, since the number of heaters can be reduced, the cost is also lower, and the heater temperatures can be made similar, reducing uneven cooking and shortening the lifespan of the heaters.

As is clear from the above description, according to the present invention, an outer circumferential heater that is energized from the beginning of the heating process and an inner circumferential heater that is energized from the middle of the heating process are disposed in the heating space. Therefore, the temperature of the upper part of the rice to be cooked in the pot can be brought close to the temperature rise at the bottom of the pot without rapidly heating the bottom of the pot, and uneven cooking can be reduced. In addition, the radiant heat of a sheathed heater has a lower altitude than that of a gas combustion flame, and by appropriately setting the sheathed heater's installation method, power balance, and heat generation control, it is easier to achieve uniform heating of the bottom of the pot. Even in large rice cookers, the thickness of the pot can be reduced to about 1.5 to 2 mm, which has the advantage of reducing the weight of the pot and providing a rice cooker that is easy to use. By making the pot thinner, it is possible to process the pot by press molding, which is advantageous in terms of cost. In addition, since the sheathed heater is a heating source with a large specific heat, it retains a high amount of heat even after the power is cut off when rice cooking is complete, and this amount of heat produces the so-called re-cooking effect, suppressing the temperature drop of the rice to be cooked. This has the advantage that it acts as heat to evaporate excess water, enhances the steaming effect, and provides delicious rice.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a commercial rice cooker showing an embodiment of the present invention, Fig. 2 is a plan view of the main body of the commercial rice cooker with the pot removed, and Fig. 3 is an electric circuit diagram of the same. , FIG. 4 is a diagram showing the temperature rise curve of the rice to be cooked, where a shows the case of the conventional rice cooker and b shows the case of the present example. 1... Outer case, 3... Inner case, 6... Pot,
17, 18, 19... Sheathed heater, 42... Circuit board with timer function, 43... Relay,
44...Temperature fuse.

Claims (1)

[Claims] 1 A heating space is formed between an inner case that houses the pot and the outer periphery of the pot, and an outer peripheral heater that supplies electricity to the heating space from the beginning of the heating process, and a heater that supplies electricity to the heating space from the beginning of the heating process. A rice cooker equipped with an inner heater.