JPH04279111A - Cooker - Google Patents

Abstract

PURPOSE:To effectively transfer heat generated by a heater to a food to be cooked in a cooking-vessel, to quicken a temperature drop, and to surely and safely apply an electric current to the heater, by a method wherein part of the bottoms surface of an outer wall for a heat-pipe type inner cooking-vessel is formed in the protruding shape downward, and thus a liquid-storing part is formed; and a heater, of which the end part is airtightly connected to the outer wall, is located in this liquid-storing part. CONSTITUTION:When a starting switch for rice-cooking is operated, an electric current is applied to a preheater and a heater terminal part is made dry. After that, the electric current is applied to a core wire through electricity-supplying pins 16 and terminals, and a sheath is heated through an insulator. Since the sheath is immersed in a working liquid 6 such as water, a proper amount of which is enclosed in a liquid- storing part 5, the working liquid 6 is quickly raised in temperature, boiled and vaporized. Since the working liquid 6 is actuated at a temperature slightly higher than a temperature of a food to be cooked, the difference between air temperature around a rice-cooker and a temperature in a heated part is small, and hence the loss of radiation is small. After rice-cooking has been finished, the temperature of boiled- rice in an inner cooking-vessel 1 falls through an inner wall 3, an outer wall 2, and an outer cooking-vessel 12, by natural radiation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pipe type cooking device used in rice cookers and the like.

0002

BACKGROUND OF THE INVENTION Various so-called heat pipe type heating cookers have been proposed in order to improve the heating temperature distribution of pots, inner pots, etc. of rice cookers. The container of this heat pipe type heating cooker has a sealed double wall structure, and a working fluid such as water that changes phase from gas to liquid depending on the temperature difference is sealed in the sealed space between the outer wall and the inner wall. It has a similar structure. During cooking, the working fluid at the bottom of the outer wall is evaporated by heat applied from a heat source such as an electric heater, and this vapor is condensed on the inner wall surface to uniformly transmit heat to the entire inner wall, making the heating temperature uniform. This allows you to cook rice with even heating. There are various methods of heating the working fluid of such a heat pipe type heating cooker using an electric heater, but when deciding on a heating method, consider heating efficiency, ease of cleaning the inner pot and outer pot, and
Handling and electrical stability of the inner pot must be considered. The usual heating method is to heat the bottom of a heat pipe-shaped inner pot using a sheathed heater or the like, but this method is inferior in terms of heating efficiency. One method to maximize heating efficiency is to place a sheathed heater in the working fluid and heat it directly. FIG. 7 shows, for example, JP-A-63-117
It is a cross-sectional view showing a conventional heating cooker shown in Publication No. 719. In the figure, 2 is an outer wall press-molded from a stainless steel plate, etc., 3 is an inner wall, and the outer wall 2 and the inner wall 3 are the upper end 4.
The outer wall 2 and the inner wall 3 are hermetically welded to form an evacuated sealed space between the outer wall 2 and the inner wall 3. 5 is a liquid reservoir formed in a downwardly convex shape at the center of the bottom surface of the outer wall 2; 6 is a hydraulic fluid such as water sealed in an appropriate amount in this liquid reservoir 5; and 7 is placed immersed in this hydraulic fluid 6. It is a circular sheathed heater, and both ends thereof penetrate the outer wall 2 and are hermetically welded. 1 is the above inner wall 2
This is an inner pot that is removably inserted into the inner pot for storing the food to be cooked.

[0003] A conventional heating cooker is constructed as described above.
Rice and water placed inside the inner pot 1 are heated by a sheathed heater 7 and cooked. The sheathed heater 7 heats the working fluid 6 by energizing it to raise the temperature and boil and vaporize the working fluid 6. The vapor of the working fluid 6 moves at the speed of sound to the inner wall 3 where the pressure is lower, that is, the temperature is lower, where it is condensed and liquefied, giving latent heat of condensation to the inner wall 3. Since a large amount of the working fluid 6 condenses in the lower temperature area, the temperature of the inner wall 3 becomes uniform as a result, and the inner pot 1 disposed inside the inner wall 3 is heated uniformly. Therefore, the temperature of the rice placed in the inner pot 1 is also uniform. The working fluid 6 condensed in the inner pot 3 falls due to gravity and returns to the fluid reservoir 5, and this cycle is repeated. After the rice cooking is completed and the meal is finished, the inner pot 1 is taken out from the inner wall 3, washed, dried, and returned to the inner wall 3 again.

0004

[Problems to be Solved by the Invention] In the conventional heating cooker as described above, the container composed of the outer wall 2 and the inner wall 3 is fixed to the rice cooker body (not shown), so that the sheathed heater 7 Although the wiring is simple, the food to be cooked receives heat indirectly from the inner wall 3 via the inner pot 1, so the temperature distribution during heating is not necessarily good, and there is a temperature distribution between the inner wall 3 and the inner pot 1. Because of the thermal resistance, the operating temperature of the working fluid 6 had to be raised, which increased heat radiation loss to the outside of the rice cooker and reduced heating efficiency. Now, in a rice cooker, after rice cooking is finished, it automatically shifts to a warming mode at around 70℃, but if the temperature drop rate due to natural heat dissipation from the boiling temperature of water, 100℃, to this 70℃ is slow, the aminocarbonyl reaction will occur during this time. As a result, the yellowing of the rice progresses and the rice ages, which is undesirable. In the conventional example above, since the rice is in the inner pot 1 inside the inner wall 3, the inner pot 1
There was also the problem that heat dissipation was inhibited due to the thermal resistance caused by this, and the temperature drop was delayed.

[0005] The present invention was made in order to solve these problems, and provides efficient heat transfer from the heater to the food to be cooked, a rapid temperature drop rate, and reliable power supply to the heater.・The aim is to obtain a heating cooking device that can be used safely.

[0006]

[Means for Solving the Problems] In the heating cooker according to the present invention, a sealed space is formed between an outer wall and an inner wall, a working fluid is sealed in this sealed space to form a heat pipe, and a portion of the bottom surface of the outer wall is formed. The part is formed in a downwardly convex shape to constitute a liquid reservoir part,
A heater, the end of which is hermetically sealed to the outer wall, is disposed within this liquid reservoir.

Furthermore, the heater is constituted by a sheathed heater in which the core wire is arranged in the shape of a hairpin in a sheath and a terminal is provided on only one side.

[0008] To supply power to the heater, a power supply pin is provided on the side of the cooker body and comes into contact with the heater terminal by vertical movement.

[0009] Also, water-free means such as a water-repellent resin coating or a preheating heater is provided around the terminals of the heater and around the power supply pins.

[0010] Furthermore, the cooking apparatus further includes an earth leakage prevention means for detecting the resistance value of the heater or detecting the state of electrical insulation between the heater and the main body of the cooking device before energizing the heater.

[0011] Furthermore, a temperature detector for detecting the cooking temperature is provided on the inner pot side.

0012

[Operation] When the heater of the cooking device constructed as described above is energized, the heater directly heats the working fluid and efficiently and uniformly heats the inner wall by heat pipe operation.

Furthermore, the power supply pin reliably supplies power to the removable heater of the inner pot.

Furthermore, the anhydrous means generates or evaporates water around the heater terminals and power supply pins to make these areas waterless.

[0015] Furthermore, the leakage prevention means detects leakage in the heater circuit in advance to ensure safety.

Furthermore, the temperature detector attached to the inner pot side accurately detects the cooking temperature.

[0017]

[Example] Example 1. 1 to 4 are diagrams showing the main parts of a rice cooker as an embodiment of the present invention. In the diagram, 1 is an inner pot, which is composed of an outer wall 2 and an inner wall 3, which are press-molded from stainless steel plate or the like. . The outer wall 2 and the inner wall 3 are hermetically welded at the flange portion 4 at the upper end, and an evacuated sealed space is formed between the outer wall 2 and the inner wall 3. Although not shown, rice and water to be cooked are directly put into the inner pot 1. Reference numeral 5 denotes a liquid reservoir formed in a donut-shaped downward convex shape on the outer periphery of the bottom surface of the outer wall 2; 6, a suitable amount of hydraulic fluid such as water is sealed in this liquid reservoir 5; and 7, a hydraulic fluid such as water is contained in the hydraulic fluid 6. This is a sheathed heater as a heating heater that is immersed. The sheathed heater 7 has a sheath 8 made of a stainless steel pipe or the like with one end sealed, and a core wire 9 made of a hairpin-shaped nichrome wire sealed therein, and formed into a circular shape as shown in FIG. 2. One end of the sheathed heater 7 passes through the bottom surface of the outer wall 2 and is hermetically welded, and a terminal plate 10 made of an electrical insulator is attached to this part. A pair of terminals 11 are provided on the terminal board 10, and the core wire 9 is connected thereto. The terminal board 10 itself is made of a water-repellent resin, or its surface is coated with a water-repellent resin. Reference numeral 12 designates an outer pot on the side of the rice cooker main body that removably houses the inner pot 1, and is formed to have substantially the same shape as the outer wall 2. The case and lid of the rice cooker are omitted. Reference numeral 13 denotes a temperature detection tube which is attached to the center of the bottom of the outer hook 12 so as to be movable up and down by a spring 14.
A temperature detector 15 for detecting the temperature of the inner pot 1 is provided inside. Reference numeral 16 designates a pair of power supply pins that can be moved up and down by a pin spring 17 provided at a position facing the terminal 11 of the outer hook 12. The power supply pin 16 is housed in a pair of pin holes 18 equipped with a shutter (not shown) that opens and closes in conjunction with the vertical movement of the temperature detection cylinder 13. The periphery of the pin hole 18 is coated with a water-repellent resin similar to that of the terminal board 10. Reference numeral 19 designates a low-power preheating heater provided near the pin hole 18. This preheating heater 19 and the water-repellent resin constitute a water-free means for the heater terminal portion. Reference numeral 20 denotes a drain hole made in the lowest part of the outer pot 12.

In the heating cooker constructed as described above, rice and water as items to be cooked are placed in the inner pot 1 and set in the outer pot 12. At this time, although not shown, the terminal plate 10 of the inner hook 1 is brought to the position of the power supply pin 16 of the outer hook 12 by a guide. When the inner pot 1 is set, the temperature detection tube 13 is pushed down, and the bottom surface of the outer wall 2 and the top of the temperature detection tube 13 come into contact. Further, in conjunction with the lowering of the temperature detection tube 13, a shutter of the pin hole 18 is opened by a mechanism not shown, and the power supply pin 16 rises and comes into contact with the terminal 11. When a rice cooking start switch (not shown) is operated, the preheating heater 19 is energized prior to energizing the sheathed heater 7 to dry the heater terminal portion. This is because the bottom of the inner pot 1 is wet when the outer pot 12 is removed.
This is to prevent the terminal 11 of the terminal board 10 and the power supply pin 16 of the pin hole 18 from causing leakage or short circuit due to moisture when the terminal 11 of the terminal board 10 and the power supply pin 16 of the pin hole 18 are set in a container. Thereafter, the core wire 9 is energized through the power supply pin 16 and the terminal 11. The temperature of the core wire 9 rises, and the sheath 8 is heated through the insulator. Since the sheath 8 is immersed in the working fluid 6, the working fluid 6 is quickly heated to boil and vaporize. The working fluid 6 uniformly heats the inner wall 3 by the same operation as in the conventional example. Therefore, the food to be cooked in the inner pot 1 is also heated uniformly without temperature unevenness. The temperature of the working fluid 6 is slightly higher than the temperature of the food to be cooked, so the maximum temperature is a little over 100°C. Therefore, the temperature difference between the ambient air temperature of the rice cooker and the heating section is small, and high heating efficiency is obtained with little heat radiation loss. In a heating method using an electric heater in a normal rice cooker, the temperature of the heater reaches several hundred degrees, resulting in large heat radiation loss and low heating efficiency. Furthermore, since the sheathed heater 7 directly heats the working fluid 6, the heating starts quickly. After the rice is cooked, the rice in the inner pot 1 is
The temperature drops through the inner wall 3, outer wall 2, and outer pot 12 due to natural heat radiation.

Example 2. In the first embodiment, the liquid reservoir 5 is provided on the outer periphery of the bottom of the outer wall 2, but if the inner pot 1 is to have sufficient strength as a pressure-resistant container, the liquid reservoir 5 may be provided on other parts of the bottom. Good too.

Example 3. Further, in the first embodiment, the sheathed heater 7 is formed into a single circle shape, but depending on the heat generation density on the surface of the sheath 8, it may be shortened to one circle or less, or conversely, the sheath heater 7 may be formed in a double or triple circle shape. You can make it heavier and longer.

Example 4. Furthermore, in the sheathed heater 7 of Examples 1 and 3, the terminals of the core wire 9 were gathered at one end, and the number of welded points with the outer wall 2 was one. 9
Terminals may be provided and welded to the outer wall 2 at two locations.

Example 5. In each of the above embodiments, the heater is a sheathed heater, but the working fluid 6 is highly electrically insulating.
Further, as long as the structure is such that contact between the heater and the outer wall 2 and inner wall 3 can be avoided, the bare core wire 9 may be placed directly in the working fluid 6.

Example 6. Further, in the first embodiment, as a measure to prevent electric leakage at the heater terminal section, a waterless means consisting of a water-repellent resin coating and a preheater 19 for drying water was provided. may be provided. As a means for this, for example, before energizing the sheathed heater 7, the resistance value of the core wire 9 is detected, and if the resistance value is abnormally smaller than the designed value, an abnormality is displayed and the energization to the sheathed heater 7 is not started. There is a method of detecting the state of electrical insulation between the heater circuit and the rice cooker body, and not starting electricity if the insulation is broken.

Example 7. FIG. 5 shows another embodiment of mounting the temperature sensor,
A temperature sensor 15 is attached directly to the surface of the inner wall 3. With such a configuration, the rice cooking temperature can be detected more accurately. Note that since the temperature of each part of the inner wall 3 is uniform, the temperature detector 15 may be attached anywhere.

Example 8. FIG. 6 shows still another embodiment of mounting the temperature sensor, in which the temperature sensor 15 is mounted on the terminal plate 1 on the outer surface of the outer wall 2.
It is installed inside 0. In this case, as in the seventh embodiment, one of the signal lines of the temperature detector 15 is connected to one of the terminals 11, and the other signal line of the temperature detector 15 is connected to one of the terminals 11.
The other end is connected to the newly provided terminal 21 for the signal line. By providing the temperature sensor 15 near the heater terminal, for example, when the contact between the terminal 11 and the pin 16 is poor, this part will generate heat due to contact resistance. It can be detected without using it.

[0026] In the above description, the present invention was applied to a rice cooker, but it goes without saying that it can also be applied to other heating containers for cooking.

[0027]

[Effects of the Invention] Since the present invention is constructed as described above, it produces the following effects.

[0028] By immersing the heater in the working liquid of the heat pipe type inner pot that houses the food to be cooked and directly heating the working liquid, the heating efficiency is high and the temperature drop due to heat dissipation after cooking is also large. Furthermore, since there is no heater on the outer pot side, the outer pot is easy to clean.

Furthermore, by using a sheathed heater having a hairpin-shaped core as the heater, there is only one welding point between the heater and the outer wall, which simplifies manufacturing.

Furthermore, by providing the pin for power supply to the heater on the outer pot side, there is no protrusion on the bottom surface of the inner pot, and the inner pot is easy to operate and clean.

[0031] Furthermore, by providing a waterless means at the terminal section of the heater, water can be drained from this part better, and residual moisture evaporates, so even if the inner pot is set in the outer pot while wet, electrical leakage etc. will not occur. It's hard.

[0032] Further, by detecting the resistance value of the heater and the insulation state between the heater and the main body of the cooking device by the leakage prevention means, it is possible to safely energize the heater.

Furthermore, by providing a temperature detector on the inner pot side, the cooking temperature can be detected more accurately and quickly.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view of the sheathed heater shown in FIG. 1 of the present invention.

FIG. 3 is a bottom view of the terminal plate portion shown in FIG. 1 of the present invention.

FIG. 4 is an enlarged sectional view of the power supply pin portion shown in FIG. 1 of the present invention.

FIG. 5 is a sectional view of a temperature sensor mounting portion showing a seventh embodiment of the present invention.

FIG. 6 is a bottom view of a temperature sensor mounting portion showing an eighth embodiment of the present invention.

FIG. 7 is a sectional view showing a conventional heating cooker.

[Explanation of symbols]

1 Inner pot 2 External wall 3 Inner wall 5 Liquid reservoir part 6 Hydraulic fluid 7 Heater 8 Sheath 9 Core wire 11 Terminal 15 Temperature detector 16 Power supply pin 19 Preheating heater

Claims (6)

[Claims] Claim 1: An item to be cooked that is placed inside the inner wall by means of a heat pipe, in which a sealed space is formed between an outer wall and an inner wall, and a working fluid whose phase changes as heat is received and radiated is sealed in the sealed space. A heating cooker for cooking food, comprising: a liquid reservoir formed by forming a part of the bottom surface of an outer wall in a downwardly convex shape; and a heater disposed within the liquid reservoir, the end of which is hermetically sealed to the outer wall. A heating cooker characterized by: [Claim 2] A claim characterized in that the heater is a sheathed heater, one end of the core wire is formed into a hairpin shape and folded back in the sheath of the sheathed heater, and the terminals are gathered at the other end of the sheath. The heating cooker according to item 1. 3. The cooking device according to claim 1, further comprising a power supply pin on the cooking device main body side facing the terminal of the heater, which contacts the heater terminal by vertical movement. 4. The cooking device according to claim 3, further comprising an anhydrous means for making the area around the heater terminal and the power supply pin anhydrous by generating or evaporating water. [Claim 5] Detecting the resistance value of the heater prior to energization;
Alternatively, the apparatus further comprises an earth leakage prevention means for detecting the electrical insulation state between the heater and the cooking device body and permitting the heater to be energized when the detection result is equal to or higher than a predetermined value. Heating cooker. 6. The heating cooker according to claim 1, further comprising a temperature detector on the inner pot side.