JPS598644Y2 - rice cooker - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a rice cooker that ensures the detection of cooked rice.

In a conventional electric rice cooker, 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 dry with less water and the lower part becomes sticky with a lot of water, resulting in uneven cooking and a loss of flavor. Recently, a heating space is provided around the outside of the pot, and a heater is placed within 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. A rice cooker using heating method 1 is being considered.

This type of rice cooker can cook rice evenly and evenly, but the thermostat, which detects the temperature of the outside bottom of the pot to determine when the rice is cooked, is heated by the radiant heat from the heater and malfunctions. If the heater turns off prematurely, the rice near the bottom of the pot may not be sufficiently cooked.

This invention was created in view of the above circumstances, and by installing a heat shield plate that covers a temperature sensing device to detect the temperature at the bottom of the pot, it is possible to cook rice evenly and to improve the cooking quality. To provide a rice cooker which can reliably detect the rise of rice, can uniformly cook the whole rice, and can greatly improve the taste of the cooked rice.

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

Reference numeral 1 denotes a substantially cylindrical outer case with an open top and bottom, and a substantially cylindrical inner case 3 serving as a pot storage section is disposed inside this with a heat insulating material 2 interposed therebetween. The upper end portion is fixed by screws or the like to an annular decorative frame 4 made of heat-resistant plastic, for example, which is fitted around the inner periphery of the upper end portion of the outer case 1 .

Reference numeral 5 denotes a bottom plate having support legs 6, which are fitted and fixed to the lower end of the outer case 1.

Reference numeral 7 denotes a pot having an outwardly directed flange 8 formed on the upper opening edge thereof, and is disposed within the inner case 3 by placing the flange 8 on the upper surface of the decorative frame 4.

The height and outer diameter of the pot 7 are each set to be smaller than the inner case 3. Therefore, a space 9 sealed by the inner case 3 is formed around the outer periphery of the pot 7, and this space 9 are continuously opposed to the outer bottom surface and outer surface of the pot 7.

Reference numeral 10 denotes an annularly curved sheathed heater with a capacity of, for example, 600 W, which is located in the space 9 at a predetermined distance from the pot 7, and whose middle portion is fixed to the inner bottom of the inner case 3 via a stone 12. Terminal portions 10a provided at both ends are removably connected to plug terminals 10b via support tubes 3a protruding from the bottom of the inner case 3.

13 is a magnetic thermostat which is a temperature sensing device disposed at the inner bottom of the inner case 3;
is a bottomed cylindrical heat transfer case with an open bottom, which is supported so as to be movable up and down by a guide cylinder 15 which is bulged in a substantially cylindrical shape at the substantially center of the inner case 3, and A compression coil spring 17 disposed between a flange 14a provided at the lower end of the case 14 and a cover plate 16 fixed to the inner case 3 so as to close the lower surface of the guide tube 15 always urges the guide tube upward. The upper surface of the heat transfer case 14 is pressed against the outer bottom surface of the pot 7.

The upper end of the guide tube 15 is formed with a flange 15a that is bent inward, so that when the pot 7 is removed from the inner case 3, the flange 14a of the heat transfer case 14 It engages with the flange 15a of the guide tube 15 to prevent it from coming off.

A magnetic body 18 is made of a magnetic shunt material and is attached to the inner bottom surface of the heat transfer case 14 with a heat transfer plate 19 interposed therebetween.

Reference numeral 20 denotes a lever with a knob 21 attached to one end by integral molding or the like, and the middle part of this lever is rotatably supported via a pin 23 by a support arm 22 protruding from the lower surface of the inner case 3. , and a rising portion 20a provided at the other end is inserted into the guide cylinder 15 through a hole 16a provided in the cover plate 16, and a permanent magnet 24 is fixed to the upper end of the rising portion 20a. ing.

The knob 21 attached to the lever 20 is attached to the outer case 1.
The lever 20 is protruded from a hole 25a of the operation panel 25 provided on the side surface of the lever 20.
6, it is always urged in the direction of arrow a.

Although not shown, a microswitch is provided at the bottom of the inner case 3 that closes when the lever 20 is pressed down, and when the lever 20 is pressed down, the permanent magnet 24 is attracted to the magnetic body 18. When this occurs, the microswitch is closed and the sheathed heater 10 is energized.

27 is a heat shield plate as a cylindrical heat shield disposed below the pot 7 so as to cover the thermostat 13, and this is disposed below the sheathed heater 10 at a predetermined interval. It is integrally provided in a protruding manner approximately at the center of the reflector plate 28, which serves as a short cylindrical reflector with a bottom.

The reflection plate 28 has insertion holes 28 a and 28 through which both ends of the sheathed heater 10 and the support member 11 are inserted.
b, and is detachably attached together with the sheathed heater 10.

As is clear from FIG. 1, the position of the sheathed heater 10 is such that its center is located slightly below a plane extending outward from the outer bottom surface of the pot 7, and the position of the thermostat 13, which is a temperature sensing device, is is located approximately at the center of the outer bottom surface of the pot 7, and therefore, at least a portion of the sheathed heater 10 is positioned so as to directly face the thermostat 13 without being obstructed by the pot 7. The heat shield plate 27 as a heating body is located between the sheathed heater 10 and the thermostat 13 having the above-described positional relationship, and covers the thermostat 13.

Reference numeral 29 denotes a hinge member 30 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 31, and a handle portion 32 for carrying is integrally formed on the upper surface.

33 is an inner cover, which is connected to the outer cover 29 via a heat insulating material 34.
is fixed to the inner surface of the

Reference numeral 35 denotes an engaging member located on the opposite side of the hinge member 30 and fixed to the upper end of the outer case 1, which engages with a retaining portion (not shown) provided on the handle portion 32 when the outer lid 29 is closed. together to hold the outer lid 29 in a closed state,
The engagement can be released by a push button 36.

Reference numeral 37 denotes an inner lid that engages and supports a retaining portion 33a provided on the lower surface of the inner cover 33 via a supporting convex portion 38, and this is in pressure contact with the flange 8 of the pot 7 when the outer lid 29 is closed. It has become.

38' is a steam vent provided on the inner lid 37, and a spherical body 39 is disposed therein as a valve body.

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

Washed rice 40 and water 41 necessary for cooking the rice 40 are stored in the pot 7, the flange 8 is placed on the decorative frame 4, the pot 7 is housed in the inner case 3, and the outer lid 29 is placed. Then, the inner lid 37 is brought into pressure contact with the upper surface of the pot 7 to close the pot 7.

Next, by pressing down the knob 21, the lever 20 is rotated in the direction opposite to the arrow a, so that the permanent magnet 24 is attracted to the magnetic body 18.

Then, based on the push-down operation of the knob 21, a microswitch (not shown) is closed, and the sheathed heater 10 is energized.

When the sheathed heater 10 generates heat, the air in the sealed space 9 is heated, causing convection as shown by arrow b in FIG. is heated, and the rice 40 in the pot 7 is cooked.

When all of the water 41 in the pot 7 is no longer absorbed by the rice 40, the bottom of the pot 7 enters a so-called dry cooking state and the temperature rises rapidly, causing the thermostat 13 to be heated via the heat transfer case 14. As the temperature of the magnetic body 18 also increases,
The magnetic permeability of the magnetic body 18 decreases rapidly.

Then, the attraction force acting between the magnetic body 18 and the permanent magnet 24 decreases, and when the attraction force becomes less than a predetermined value, the rotating force acting on the lever 20 in the direction of arrow a by the recoil spring 26 increases the attraction force. The permanent magnet 24 is separated from the magnetic body 18 and moved downward, the knob 21 is returned upward together with the lever 20, and a microswitch (not shown) is opened to close the sheathed heater 10.
is cut off.

Now, when 1 liter of rice 40 is cooked using the rice cooker of this embodiment, the upper, middle, and lower parts (A and B in Fig. 1) of rice 40 are shown.
The temperature (denoted by and C) has a characteristic as shown in FIG. 2, where the vertical axis represents the temperature t (° C.) and the horizontal axis represents the time T (minutes).

That is, in this embodiment, the space 9 is shaped so as to continuously face the outer bottom surface and the outer surface of the pot 7, and the sheathed heater 10 is arranged in the space 9 at a predetermined distance from the pot 7. Because of this, the convection shown by arrow b is performed extremely well, and the temperature above the space 10 tends to rise first.
Therefore, the temperature of the upper part A of the rice 40 tends to rise earlier than the temperature of the middle part B and the lower part C.

Now, the water absorption rate of rice 40 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 rice 40 is higher than that of the middle part B and lower part C of 60°C to 70°C. By reaching the range of , first, rice 4 located in upper A
0 will perform the water absorption action.

As the water level in the pot 7 decreases as the rice cooking progresses, the rice 40 in the upper part A, where the water 41 disappears the fastest, reaches the optimum water absorption temperature (60°C to 70°C) at the beginning of rice cooking, and the rice 40 in the lower part where the water 41 remains until the end. The rice 40 in C reaches the optimum temperature for water absorption at the end of cooking and the temperature rises rapidly.

That is, the upper part of the pot 7 reaches the optimum water absorption temperature quickly, but the water 41 disappears quickly, and the lower part of the pot 7 retains water 41 until near the end of rice cooking, but does not reach the optimum water absorption temperature. Because of this, the rice 40 in the pot 7 absorbs water for a substantially constant time no matter where it is located in the upper part A, the middle part B, or the lower part C, and has a uniform water absorption rate as a whole. It can be cooked.

Furthermore, in this embodiment, since the thermostat 13 is covered with the heat shield plate 27, the radiant heat from the sheathed heater 10 does not directly reach the thermostat 13. It is operated only by temperature, and it is possible to reliably prevent rice 40 near the bottom of pot 7 from not being sufficiently cooked due to premature cutting due to radiant heat from sheathed heater 10.

Furthermore, in this embodiment, since the heat shield plate 27 and the reflection plate 28 are integrally formed, the radiation from the surface of the sheathed heater 10 that does not face the pot 7 can be reflected in the direction of the pot 7 by the radiant plate 28. In addition to the convection shown by arrow b, the pot 7 is heated by both radiant heat directly directed from the sheathed heater 10 toward the pot 7 and radiant heat reflected by the reflector 28 and directed toward the pot 7.
Thermal efficiency is improved, making it possible to shorten rice cooking time and reduce power consumption.

Incidentally, the position of the sheathed heater 10 is not necessarily limited to the position of the above-described embodiment, and the position can be changed as appropriate as long as the above-mentioned effect can be obtained, and the thermostat 13 can also be placed outside the pot 7. It may be brought into contact with any position on the bottom surface. Therefore, if the heat shield plate 7 is provided when at least a part of the sheathed heater tube is in a positional relationship directly facing the thermostat 13, the thermostat 13 can be brought into contact with the sheathed heater 7. Direct radiant heat can prevent premature breakage.

Further, in the above embodiment, the heat shield plate 27 is integrally formed with the reflector plate 28, but the reflector plate 28 may be provided as necessary, and as shown in FIG. The heat shield plate 42 as a body may be fixed to the bottom surface of the inner case 3 by, for example, welding.

As explained above, the present invention not only allows rice to be cooked evenly, but also allows reliable detection of cooked rice to ensure uniform cooking of the entire rice, and greatly improves the taste of cooked rice. We can provide equipment.

[Brief explanation of drawings]

Figures 1 and 2 show one embodiment of the present invention; Figure 1 is a longitudinal sectional view, Figure 2 is a temperature characteristic diagram, and Figure 3 is a schematic diagram showing another embodiment of the present invention. FIG. In the drawing, 1 is an outer case, 3 is an inner case, 7 is a pot, 9 is a space, 10 is a heated heater, 13 is a thermostat (temperature sensing device), 18 is a magnetic material, 24 is a permanent magnet, and 27 is a heat shield plate (heat shield), 28 is a reflector (reflector), 30 is an outer cover,
40 is rice, 41 is water, and 42 is a heat shield plate.

Claims (2)

[Scope of utility model registration request] 1. a sealed heating space formed by covering the outer bottom surface and the outer surface of the pot with an inner case at predetermined intervals, and a temperature sensing device in contact with the outer bottom surface of the pot; The rice cooker is disposed in the space at a predetermined distance from the pot and is at least partially obstructed by the pot so that the optimum water absorption temperature in the pot shifts from the top to the bottom of the rice as cooking progresses. A rice cooker comprising: a heater directly facing the temperature sensing device; and a heat shield provided between the heater and the temperature sensing device and covering the temperature sensing device. 2. 2. The rice cooker according to claim 1, wherein the heat shield integrally has a reflecting part that reflects heat from the heater toward the pot.