JPS5951292B2 - rice cooker - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rice cooker with an improved heating method.

Conventionally, an electric rice cooker is a type in which, for example, a pot is removably placed on top of a hot plate having an electric heater, and the heat of the electric heater is transferred from the hot plate to the bottom of the pot to cook rice.

However, when rice is cooked in a rice cooker with such a conventional structure, the upper part becomes fluffy with less water, and the lower part becomes sticky with a lot of water, resulting in uneven cooking and a deterioration in overall taste. There was.

In addition, conventional structures require strict dimensional accuracy to ensure that the hot plate and pot are in close contact with each other, resulting in high costs.If the contact surfaces between the two become deformed or corroded during use, heat transfer may be impaired. The disadvantage is that the cooking becomes even and the cooking becomes even more uneven.

The present invention has been made in view of the above circumstances, and includes storing a pot in a pot storage section, disposing a heater in a space within the pot storage section at a predetermined distance from the pot, and disposing a heater on a side surface of the pot. By making the rice cooker and the side surface of the pot storage part come into contact with each other, it is possible to cook rice evenly, and the taste of the cooked rice can be greatly improved.Moreover, the cost is low and it is easy to handle. The purpose is to provide a rice cooker with a high quality rice cooker.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Reference numeral 1 denotes a substantially bottomed cylindrical outer case with an open upper surface, and a bottom frame 3 having support legs 2 is fitted and fixed to the lower end of the outer case.

Reference numeral 4 denotes an inner case serving as a bottomed cylindrical pot storage section with an open top surface, which is disposed inside the outer case 1 via a heat insulating material 5; It is fixed with screws to an annular decorative frame 6 made of heat-resistant plastic, for example.

The inner case 4 is a press-molded aluminum product, and at least the inner surface is mirror-finished by chemical polishing or electrolytic polishing, and the side surface 4a has a tapered shape that becomes slightly larger in diameter toward the top. It is formed.

7 is an annularly bent sheathed heater with a capacity of 600 W, for example, which is connected to the inner case 4 via a support member 8 and an insulator 9.
is supported at a predetermined distance from the bottom surface 4b of the
Terminal portions 7a provided at both ends are removably plug-connected to plug-in terminals 10 provided at the bottom of the inner case 4.

Reference numeral 11 denotes a bottomed cylindrical pot with an annular flange portion 11a formed at the upper end, and the bottom portion 11b is substantially planar.
In addition, the side surface portion 11C is formed in an inclined taper shape similarly to the side surface portion 4a of the inner case 4, and a smooth circular arc surface lid is formed between the bottom surface portion 11b and the side surface portion 11C.

The pot 11 is arranged in the inner case 4 so that the flange portion 11a is located above the decorative frame 6 over its entire circumference and the side portions 11C and 4a are in close contact with each other. However, the height dimension H is set smaller than that of the inner case 4, so that the bottom surface portion 11b is spaced apart from the sheathed heater 7 by a certain amount.

That is, a heating space K is formed by the inner case 4 at the outer bottom of the pot 11, and the sheathed heater 7 described above is located inside this space.

By the way, the diameter d of the aforementioned sheathed heater 7 is set to be slightly smaller than the diameter of the lower part of the pot 11, and the sheathed heater 7 is located below the arcuate surface lid.

The pot 11 is, for example, a press-molded product made of aluminum, and the outer surface is alumite-treated, and the inner surface is alumite-treated or coated with fluororesin.

Reference numeral 12 denotes a bottomed cylindrical protective case with an open bottom, which is supported in a vertically movable manner by a guide tube 13 erected at the inner bottom of the inner case 4, and is provided at the lower end of the protective case 12. The upper surface of the protective case 12 is pressed against the bottom surface 11b of the pot 11 by being constantly urged upward by a compression coil spring 14 disposed between the flange 12a and the inner case 4.

An inwardly curved flange 13a is formed at the upper end of the guide tube 13, and when the pot 11 is removed from the inner case 4, the flange 12a of the protective case 12 is attached to the guide tube 1.
It engages with the flange 13a of No. 3 to prevent it from coming off.

Reference numeral 15 denotes a magnetic body made of a magnetic shunt material stuck to the inner bottom surface of the protective case 12.

Reference numeral 16 denotes a lever with a knob 17 attached to one end by integral molding or the like, and the middle part of this lever is rotatably supported by a support arm 18 protruding from the lower surface of the inner case 4 via a pin 19. , and insert the rising portion 16a provided at the other end into the guide tube 13 through the hole 4C provided in the bottom surface 4b of the inner case 4, and attach the permanent magnet 20 to the upper end of the rising portion 16a. It's stuck.

A knob 17 attached to the lever 16 projects outward from a hole 21a of an operation panel 21 provided on the side surface of the outer case 1, and the lever 16 is attached to a torsion coil spring 2.
2, it is always urged in the direction of arrow a.

Although not shown, a microswitch is provided at the bottom of the inner case 4 and closes when the lever 16 is pressed down, and the permanent magnet 20 is attracted to the magnetic material 5 by pressing down on the lever 16. When this happens, the microswitch is closed and the sheathed heater 7 is energized.

23 is a hinge member 24 fixed to the upper end of the outer case 1
The outer lid is made of, for example, plastic and is rotatably supported via a pin 24a, and a handle portion 25 for carrying is integrally formed on the upper surface.

26 is an inner cover, which is connected to the outer cover 23 via a heat insulating material 27.
is fixed to the inner surface of the

Reference numeral 28 denotes an engaging member located on the opposite side of the hinge member 24 and fixed to the upper end of the outer case 1, which engages with an engaging portion (not shown) provided on the handle portion 25 when the outer lid 23 is closed. together to hold the outer lid 23 in a closed state,
The engagement can be released by a push button 29.

Reference numeral 30 denotes an inner lid that is engaged and supported by an engaging portion 26a provided on the lower surface of the inner cover 26 via a supporting convex portion 31, and this is in pressure contact with the flange portion 11a of the pot 11 when the outer lid 23 is closed. It has become.

Reference numeral 32 denotes a steam vent provided in the inner lid 30, which is inserted into an insertion hole 33 provided in the outer lid 23, and a spherical body 34 is disposed therein as a valve body.

Next, the operation of this embodiment configured as above will be explained.

Washed rice 35 and water 36 necessary for cooking the rice 35 are stored in the pot 11, the pot 11 is housed in the inner case 4, the outer cover 23 is closed, and the inner cover 30 is closed as a pot. The pot 11 is closed by pressing against the upper surface of the pot 11.

Next, by pressing down the knob 17, the lever 16 is rotated in the opposite direction of arrow a, so that the permanent magnet 20 is attracted to the magnetic body 15.

Then, based on the push-down operation of the knob 17, a microswitch (not shown) is closed, and the sheathed heater 7 is energized and generates heat.

By the way, since the sheathed heater 7 is disposed so as to face the arcuate surface 11d of the pot 11, the radiant heat from the sheathed heater 7 is most efficiently transmitted to the arcuate surface 11d via the space K. Water 3 in pot 11 that contacts 11d
6 is heated to a high temperature, causing local convection as shown by arrow b in FIG.

That is, the water 36 in contact with the inner wall of the pot 11 is more likely to undergo convection than the water 36 in the center of the pot 11, and rises along the inner wall of the pot 11 and goes to the top.

Also, at the same time as this action, the bottom surface 4b of the inner case 4 is also heated by the heater 7.
At this time, the inner surface of the inner case 4 is mirror-treated to reflect the heat.
Since each plate is thin, approximately 1 mm thick, it also has a heat conduction effect.
Due to this heat conduction, heat is evenly transmitted to the side surface 4a of the inner case 4, and is transmitted to the side surface 11C that is in close contact with the side surface 4a, and is also transmitted to the circular arc surface 11d via the space K by the aforementioned radiation. The heat given to the side part 11
Since the heat is transmitted to C, the synergistic effect of the heat of these FLs also heats the water that comes into contact with the side surface portion 11C well, thereby promoting the convection of the water 36 shown by the arrows described above.

Therefore, the temperature of the upper part, middle part, and lower part (indicated by A, B, and C in FIG. 1) of the rice 35 stored in the pot 11 is such that the temperature of the upper part A is higher than the temperature of the middle part B and the lower part C. tends to rise.

The heat from the sheathed heater 7 is transferred to the pot 11 by heat transfer.
However, as mentioned above, the heat is most efficiently transmitted to the water 36 that is in contact with the arcuate surface 11d closest to the sheathed heater 7, and the heat is transmitted to the pot 11 itself and the inner case 4.
Since the side part 11C is well heated by the heat transfer from the bottom part C, the heat of the sheathed heater is hardly supplied to the bottom part 11b of the pot 11 in the early and middle stages of rice cooking, and the heat is supplied to the bottom part C.
temperature rise becomes slower.

Then, as the rice 35 in the upper part A absorbs more water as the rice cooking time progresses, the water level decreases, and the water level in the upper part A decreases until now.
The heat conduction is worse than if there had been a hole (the rice acts as a kind of thermal insulator), and the heat transfer is gradually from upper part A to lower part C.
In the final stage of rice cooking, sufficient heat is conducted to the bottom surface 11b of the pot 11, and heat is given to the water 36 from the bottom surface 11b of the pot 11.

Now, the water absorption rate of the rice 35 is most remarkable when the temperature is in the range of 60°C to 70°C, and the temperature of the upper part A of the pot 11 is lower than 60°C to 60°C for the reason mentioned above than the middle part B and the lower part C. When the temperature reaches the range of 70° C., the rice 35 located in the upper part A starts to absorb water.

Then, as the rice cooking time elapses, the water 36 in the pot 11
The water level drops as water is absorbed by rice 35,
The rice 35 located in the upper part A is automatically prevented from absorbing more water than necessary, and the middle part B, whose temperature rises later than the upper part A, gradually reaches the range of 60°C to 70°C, and the middle part B The water absorption effect of rice 36 located at 36 is increased.

Further, as time passes and the water absorption action of the rice 36 located in the middle part B progresses, the water level in the pot 11 further decreases as described above, and the rice 36 located in the middle part B is also prevented from absorbing water more than necessary. , the rice 36 located in the lower part C, where the temperature rises later than the middle part B, absorbs more water.

When all of the water 36 in the pot 11 is absorbed by the rice 35 and disappears, the temperature of the bottom portion 11b of the pot 11 rises rapidly due to the so-called dry cooking state.
2, the temperature of the magnetic body 15 also rises, and the magnetic permeability of the magnetic body 15 decreases rapidly.

Then, the attraction force acting between the magnetic body 15 and the permanent magnet 20 decreases, and when the attraction force becomes less than a predetermined value, the spring 2
2, the rotational force acting on the lever 16 in the direction of arrow a exceeds the attraction force, and the permanent magnet 20 is moved downward away from the magnetic body 15, and the knob 17 is returned upward together with the lever 16. Then, a microswitch (not shown) is opened and the sheathed heater 7 is cut off.

By the way, in order to eliminate the drawbacks of the conventional rice cooker, the present applicant has recently installed a pot accommodating section 51 around the outer periphery of the pot 50, as shown in the schematic diagram shown in FIG. A heating space 52 facing continuously on the side surface is provided, and a sheathed heater 53 is disposed within this space 52 at a predetermined distance from the pot 50, so that the rice is cooked uniformly. However, this rice cooker tends to have relatively low thermal efficiency because the heat from the heater 53 is transferred to the pot 50 using air convection generated within the space 52. , and continued research and development to improve thermal efficiency.

Now, FIG. 2 shows the experimental results when 35 rice was cooked for 1.41 minutes using the rice cooker according to the embodiment of the present invention shown in FIG. 1 and the rice cooker shown in FIG. Temperature T('
C) and time t (minutes) is plotted on the horizontal axis.

In addition, in Figures 1 and 3, the diameter of the lower part of the pot 11.50 = 190 mm, the height H = 140 mm, and the interval h =
10mm, diameter d of sheathed heater 7.53 = 150mm
When cooking 1.41 rice 35, the water + rice capacity is about 2300 cc and the water level line W is about 85 mm.

Further, the cross-sectional diameter of the sheathed heater 7.53 is 8 mm, so the distance between the outer bottom surface of the pot 11 and the upper surface of the sheathed heater 7 is 6 mm.

Further, the capacity of each of the sheathed heaters 7 and 53 is 600W.

In Fig. 2, A and A' are the upper part of rice 35 (pan 11.
(center point 10 mm below the water surface of pot 11.50), c, c' are the lower part of rice 35 (center point 10 mm above the inner bottom surface of pot 11.50), B, B' are the middle part of rice 35 (A, A' and B, B'
1 and 2), and each measuring point is indicated by the same reference numeral in FIGS. 1 and 3.

That is, during rice cooking, the temperature of the upper parts A and A' rises first, and the temperature of the lower parts C and C' tends to rise later than the upper parts A and A' and the outer parts B and B'. is the lower part c,
This is the time required for c' to reach 100° C., and the rice cooker of this embodiment shown in FIG. 1 completes cooking in 25 minutes, while the rice cooker shown in FIG. 3 takes 27 minutes to complete cooking.

Therefore, with the rice cooker of this example, the rice cooking time can be reduced by 2 minutes compared to the rice cooker shown in Fig. 3, and the electric power is 600 (W) x
="-"--120 (W) by 60 (minutes), and an improvement in thermal efficiency equivalent to this 20W was achieved.

As described above, according to this embodiment, the temperature distribution inside the pot 11 is as follows:
The temperature in the upper part A tends to be high and decreases towards the middle part B and lower part C. Therefore, the temperature of the pot 1 based on the progress of rice cooking
Pot 1 that runs out of water the quickest due to a drop in the water level in pot 1
The rice 35 in the upper part A of 1 is at the optimum temperature for water absorption (60
℃ to 70℃) and contains water 36 up to 11.
The rice 35 in the lower part C reaches the optimum water absorption temperature at the end of cooking.

That is, the upper part of the pot 11 quickly reaches the optimum temperature for water absorption, but the water 36 also runs out quickly, and the lower part C of the pot 11 quickly reaches the optimum temperature for water absorption.
There is water generation 36 near the end of rice cooking, but it is slow to reach the optimum water absorption temperature, so the rice 35 in the pot 11 absorbs water no matter where it is located in the upper part A, the middle part B, or the lower part C. The cooking time is approximately constant, and the rice can be cooked with a uniform water absorption rate as a whole.Moreover, at the end of cooking, the rice 35 located in the upper part A and the middle part B acts as a heat insulating layer, so the rice 35 in the lower part C The temperature of rice 35 can rise rapidly, and the cooking time will not be unnecessarily prolonged.

By the way, the conventional structure uses a heater to heat the entire bottom of the pot, so the temperature at the bottom of the pot near the heater tends to rise before the temperature at the top, and as rice cooking progresses, the temperature rises the most. The temperature rise at the top of the pot, where water runs out quickly, is delayed, resulting in the rice being cooked in a fluffy state with low water absorption, and conversely, the temperature rises fastest at the bottom of the pot, where water is lost at the end of cooking, and the rice remains at a high temperature for a long time. Because of this, the rice absorbs more water than necessary and ends up cooking in a sticky state, resulting in uneven cooking and bad taste.

However, in this embodiment, since the rice 35 in the pot 11 is cooked in a substantially uniform water absorption state, there is no uneven cooking and the taste can be greatly improved.

In addition, in the above embodiment, the pot 11 is housed in the inner case 3 with a predetermined distance from the sheathed heater 7, so strict dimensional accuracy is required as in the case of a pot that is closely attached to a conventional heating plate. Since it does not require any heat transfer or heating plates, processing is very simple and costs can be significantly reduced, and heat conduction does not change significantly due to deformation, corrosion, etc. It also becomes easier to handle.

In addition, in this embodiment, the side surface 11C of the pot 11 and the side surface 4a of the inner case 4 are brought into contact to minimize the volume of the space, as is clear from the experimental results shown in FIG. Thermal efficiency can be improved more than the method shown in FIG. 3 in which a large space 52 is provided on the outer surface of the pot 50 and the pot 50 is heated using air convection within the space 52.

In the above embodiment, the side surface 11C of the pot 11 and the inner case 4
Although the side surface portion 4a of the pan 11 is formed into a linearly tapered shape,
The side surface portion 11C of the inner case 4 and the side surface portion 4a of the inner case 4 may be formed into a generally tapered shape in which the inner and outer diameters of the upper part are larger than the inner and outer diameters of the lower part, and the whole is gently spherical, so that the two contact each other. .

Furthermore, in the above embodiment, the surface of the inner case 40 is mirror-finished to improve heat reflection, and the outer surface of the pot 11 is alumite-treated to improve heat absorption, resulting in even better thermal efficiency. However, these treatments may be provided as necessary.

As explained above, the present invention provides a rice cooker that can cook rice evenly and greatly improve the taste of the finished rice, is inexpensive, is easy to handle, and has excellent thermal efficiency. can.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the present invention; Figure 1 is a cross-sectional view, Figure 2 is a temperature characteristic diagram showing experimental results, and Figure 3 is a schematic diagram showing a conventional structure. It is a configuration diagram. In the drawing, 1 is an outer case, 4 is an inner case (pot storage part), and 4 is an outer case.
a is a side part, 7 is a sheathed heater, 11 is a pot, 11C is a side part, 15 is a magnetic body, 20 is a permanent magnet, 23 is an outer lid, 2
6 is the inner cover, 30 is the inner lid, 35 is rice, 36 is water, 50
51 is a pot storage section, and 53 is a sheathed heater.

Claims (1)

[Scope of Claims] 1. A pot for storing food to be cooked, an outer case having a pot storage part for storing the pot, and a heating space provided on the outside of the pot by the pot storage part. , a heater provided in the space at a predetermined distance from the pot and heating the pot through the space, the side surface of the pot being connected to the side surface of the pot storage section. A rice cooker characterized by contact. 2. A patent characterized in that the side part of the pot storage part is formed in a substantially tapered shape that widens upward, and the side part of the pot is formed in a substantially tapered shape that slopes like the pot storage part. A rice cooker according to claim 1.