JPH0710244B2 - Electric pot - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric pot, and more particularly, to an electric pot which keeps a temperature within a predetermined range after water is completely boiled.

[0002]

2. Description of the Related Art Conventionally, an electric pot has a structure in which a hole is formed through a vacuum layer of a metal vacuum double container, and a heater is watertightly inserted into this portion from the outside, or a lower part of the vacuum double container. Of the structure in which the heater is attached from the outside, or a structure in which the heater is directly brazed to the bottom of the middle container of the vacuum double container and the airtight terminal is provided in the outer container to draw out the lead wire. Things are known. In this kind of electric pot, when boiling water, heating is first started by the main heater and the heat retention heater, and the water temperature or the temperature of the container corresponding thereto is higher than the temperature (lower limit temperature) at which the main heater is turned on and the main heater is turned off. When it reaches a predetermined temperature lower than the temperature (upper limit temperature), the heat retention heater is turned off, while heating is continued only by the main heater to boil water, and when the water temperature reaches the upper limit temperature, the main heater is turned off. In general, the warming heater is turned on and off to maintain the hot water at a temperature within a predetermined range between the upper limit temperature and the lower limit temperature (that is, the upper limit temperature and the lower limit temperature). In addition, many electric pots of this type are equipped with a bellows pump for sending air into the container in order to facilitate pouring.

[0003]

However, in the conventional electric pot, the heat-retaining heater is turned off at a heat-retaining temperature lower than the upper limit temperature, and therefore, only the main heater is heated up to the upper-limit temperature after reaching the heat-retaining temperature. As a result, the rate of rise of the water temperature is inevitably slower than before, and as a result, there is a problem that the time from the boiling state to the heat retention state, and thus the boiling time, becomes longer.

An object of the present invention is to shorten the boiling time of an electric pot.

[0005]

As a means for solving the above-mentioned problems, the present invention turns off a resistor for high heat generation when the temperature of water in a container reaches a complete boiling temperature, that is, a boiling point, A first control unit for turning on at a boiling water operation lower limit temperature or less, and the low heat generation resistor together with the high heat generation resistor are turned off, and after the high heat generation resistor is turned off, the boiling water operation lower limit temperature and the complete boiling A second control unit for turning on and off within a predetermined temperature range between the temperature and the temperature is provided.

[0006]

[Function] The high heating resistor and the low heating resistor are used for boiling water until the water temperature reaches the complete boiling temperature, and when the boiling temperature is reached and the boiling is completed, the high heating resistor and the low heating resistor are heated. After that, stop the energization to and keep the heat by turning on and off only the low heat-generating resistor.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of an electric pot according to the present invention, 10 is a heater having a water level detecting electrode, and 11a.
11e is a water level detection electrode, 12 is a metal vacuum double container, an inner container 12a, an outer container 12b, and an exhaust tip tube 12
It is composed of c, and a vacuum is provided between the middle container 12a and the outer container 12b. A metal inner lid 13 is brazed or welded to the upper open end of the vacuum double container 12 and has an opening 14. The heater 10 has a mounting bracket 15 on its upper end side.
However, bottoms 18 for closing the hollow portions are attached to the lower ends thereof, and are fastened to the inner lid 13 by screws with a metal fitting 15 via packing. A temperature sensor 16 (see FIG. 5) is placed in the hollow portion of the heater 10, and this sensor is fixed to the bottom 18. Reference numeral 17 is a micro switch, 19 is a support metal fitting, 20 is an exterior body portion, 21 is an exterior bottom portion, 22 is an exterior shoulder body, 23 is an outer lid, and a level as a display element to be described later is provided on the pouring port side of the exterior body portion 20. A meter 50 is attached. The shoulder body 22 has an opening 14 in the inner lid 13.
The inner plug 25 is detachably inserted into the.

The heater 10 is, as shown in FIG.
A low heat generating resistor 2 and a high heat generating resistor 3 are embedded in the surface layer of the ceramic substrate 1 so as not to come into contact with water, and these are connected to the external connection terminal 4 by the conductor 5 embedded in the ceramic substrate 1. It is connected to the. The low heat-generating resistor 2 functions as a heat-retaining heater, and the high heat-generating resistor 3 functions as a main heater. However, even if the amount of water in the container decreases, these generate convection in the water and heat it evenly up and down. Therefore, when the heater 10 is attached to the pot, it is embedded in one end side of the ceramic base 1 which is the lower side, and the external connection terminal 4 is externally provided in the other end side of the ceramic base 1.

The pot heater having the above structure can be manufactured, for example, as follows. First, as shown in FIG. 3, a rod-shaped substrate main portion 1a is prepared by a ceramic material powder slurry, while a ceramic sheet 1b is prepared, and an ink made of a resistance material is printed on the ceramic sheet 1b to produce a low heat-generating resistor 2. Then, the resistance films 2'and 3'which form the high heat generating resistor 3 and several conductive films 5'which form the conductor as the lead wire are formed. Next, the ceramic sheet 1b is placed with the surface on which the resistance film is formed inside, and the main body portion 1 of the base body 1
It can be easily manufactured by winding it on a and firing it to integrate them. As for the external connection terminal, a through hole 7 is previously formed in the ceramic sheet at a position where the external connection terminal is to be formed, and a conductive paste is applied from the front surface to the through hole 7 to form a conductive film 5'formed on the back surface. Are conducted, and they are formed by firing and baking. Further, in order to form the water level detection electrode, the through hole 8 is opened at the position where the electrode of the ceramic sheet is to be formed, the conductive paste is applied from the front surface onto the through hole 8, and the conductive film formed on the back surface. And conduct. After firing, the conductive film on the through holes 8 is formed by plating nickel, silver, or the like. The resistance film 2'has a narrow width so as to have a high resistance, and the resistance film 3'has a wide width so as to have a low resistance. In addition, the water level detection electrode 11
b to 11e are used to detect water conduction with the reference electrode and to display the water amount by the water level display level meter 50, and also to determine the boiling time according to the water amount. A portion between 11a and 11c is used to prevent the high heating resistor 3 from being cooked in the air, and a portion between the electrodes 11a and 11b is used to prevent the low heating resistor 2 from being cooked in the air.

In the above embodiment, the main body portion 1a is formed in a rod shape, but it may be formed in a cylindrical shape. Alternatively, the main body portion 1a is formed in a plate shape, and the resistive film and the conductive film are formed on the main body portion 1a. After laminating the ceramic sheets 1b having the above-mentioned structure, it may be fired. Further, the pattern of the resistance film may be formed independently as shown in FIG. 4 instead of the pattern shown in FIG. As the material for forming the resistance films 2'and 3'and the conductive film 5 ', a known conductive paste containing silver, nickel or tungsten may be used.

The inner plug 25 has a pumping pipe 26 and a water injection pipe 27, and a safety valve 28 is arranged in a flow path connecting them. A bellows pump including a bellows 30, a spring 31, and a bellows upper plate 33 is provided inside the outer lid 23. In addition, a problem with the conventional electric kettle equipped with a bellows pump, that is, when water is boiled, that is, completely boiled, the generated steam enters the bellows and deforms the bellows 30, so that the maximum temperature of hot water, In order to solve the problem that the upper limit temperature is suppressed to 95 ° C. and complete boiling cannot be achieved, in this embodiment, the steam cylinder 32 that penetrates the bellows 30 and connects the inside and the outside of the container.
A valve element 35 for opening and closing the exhaust port 34 of the bellows pump is externally provided on the lower end side of the steam cylinder 32.
In the illustrated example, the seal packing 36 attached to the bottom plate 37 of the outer lid 23 is used as the valve seat 38, but the lower end portion of the exhaust pipe 39 of the bellows may be used as the valve seat. Since the upper end of the steam cylinder 32 is fixed to the intake cylinder 40 formed on the bellows upper plate 33, the valve body 3 is operated by the action of the spring 31.
5 is brought into close contact with the valve seat 38. A packing 41 is fitted to the intake cylinder 40 of the bellows upper plate 33, and the intake hole 43 is opened and closed by the packing 41 and the cap 42. The cap is closed by a spring 44 mounted on the intake cylinder 40. It is biased upward. Reference numeral 45 is a steam hole, and 46 is a pusher.

The electric pot is provided with a control device 51, which constitutes a heater control circuit, a liquid amount display device, and an empty cooking prevention device. As shown in FIG. 5, this control device includes a pulse generator 53, a water level detector 54, and a heater control circuit 6
5, 66, a temperature detecting section 59, and an LED driving section 60. The pulse generator 53 generates a pulse voltage having a pulse output period of 1 ms and a rest period of 4 seconds, for example, and applies the pulse voltage between the reference electrode 11a and the other water level detection electrodes 11b to 11e, Receiving the pulse voltage, the water level detection unit 54 detects conduction / non-conduction between the reference electrode 11a and other electrodes. The temperature detector 59
The temperature is detected by the signal from the temperature sensor 16 attached to the bottom of the heater 10, and the triac trigger units 57, 5 are connected.
Signals are output to 8 respectively.

The heater control circuit includes a temperature detector 59 and a first controller 66 for controlling the high heat generating resistor 3,
The first control unit 66 includes a triac trigger unit 58 and a triac 56 connected in series to the high heat generation resistor 3, and a temperature detection unit. Upon receiving a signal from 59, the high heat generating resistor 3 is turned off when the water temperature reaches the complete boiling upper limit temperature, and the high heat generating resistor 3 is turned on when the water temperature is lower than the heat retention temperature and below the operation lower limit temperature. . In addition, the second control unit 6
Reference numeral 5 includes a triac trigger unit 57 and a triac 55 connected in series with the low heat-generating resistor 2, and at the same time as the high heat-generating resistor 3 when receiving a signal from the temperature detecting unit 59, that is, completely. The low heat-generating resistor 2 is turned off at the boiling temperature, and the low heat-generating resistor 2 is turned on / off at a predetermined temperature between the complete boiling temperature and the boiling lower limit temperature during heat retention. In addition, the first and second control units include the water level detection unit 5
4, an air heating prevention device is configured to stop the energization of the low heat generation resistor 2 and the high heat generation resistor 3 in response to a trigger inhibition signal from the water level detection unit 54. The LED drive unit 60 displays a display element, for example, each display element 6 of the level meter 50 according to the output signal from the water level detection section 54.
Drive 1 Further, in order to prevent electric shock when the heater is damaged, etc., a voltage detection unit 62 for detecting the voltage of the container 12 and a power supply disconnection unit 63 for turning off all circuits by an output signal from the voltage detection unit 62 are incorporated. Further, a micro switch 17 is provided at the bottom of the pot to turn off the power when the pot is lifted or when it falls.

When the electric kettle having the above-mentioned structure is used, when the container 12 is filled with cold water and the plug 70 is inserted to energize the electric kettle, the high-heat-generating resistor 3 and the low-heat-generating resistor 2 are used to boil water to a predetermined temperature. When the water has boiled after a lapse of time, it is determined that the water temperature has reached the complete boiling temperature by the signal from the temperature detection unit 59 connected to the temperature sensor 16, and the first control unit 6
6 and the second control unit 65 stop energizing the high heat generation resistor 3 and the low heat generation resistor 2 and thereafter, the second control unit 6
5 turns on / off the low heat-generating resistor 2 in response to the output signal from the temperature detecting unit 59, and sets the heat retention lower limit temperature higher than the boiling water operation lower limit temperature at which the high heat generating resistor turns on but lower than the complete boiling temperature. Insulation is performed within the temperature range of the complete boiling temperature.

Further, in the conventional electric pot, when it is completely boiled, steam enters the bellows and the bellows is deformed and cannot be used. Therefore, the upper limit temperature (maximum temperature) is suppressed to 95 ° C. In the illustrated example, a steam cylinder 32 penetrating the bellows 30 is provided, and steam is prevented from entering the bellows 30 by the valve body 35, and at the same time, discharged from the steam cylinder 32 to the outside through the intake hole 43 and the steam hole 45. Therefore, the deformation of the bellows can be prevented, and therefore, the upper limit temperature can be set to the complete boiling temperature.

Further, in the above embodiment, the heater is brought into direct contact with the contents, for example, water in order to reduce the heat loss and improve the thermal efficiency. A structure may be adopted. However, if the heater is brought into direct contact with the contents, there is no need to perform emptying or other processing for mounting the heater on the container, so the manufacturing process of the container is small, pot assembly is easy, and the cost is low. It can be manufactured. Moreover, if not only the metal vacuum double container but also the glass vacuum double container is used as the container, there is an advantage that the heat retaining property is remarkably improved and the power consumption required for the heat retaining can be extremely reduced. Also, as in the example,
When a heater with a water level detection electrode is used, it is not necessary to form a hole for communicating with the liquid volume display tube at the bottom of the container as in the conventional case, and an independent water level detection electrode is provided on the container wall or the container is used. No need to hang from the opening of
There is also an advantage that the pot can be easily manufactured and assembled.

[0017]

As described above, according to the present invention, the heating temperature is raised to the upper limit temperature, that is, the complete boiling temperature by the high heat resistance resistor and the low heat generation resistor, so that the boiling time can be shortened.

[Brief description of drawings]

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

FIG. 2 is a partial cutaway view of a heater.

FIG. 3 is a developed perspective view of a heater.

FIG. 4 is a development view showing a modified example of a heater pattern.

FIG. 5 is a block diagram of an electric circuit of an electric pot.

[Explanation of symbols]

1: Ceramic substrate, 2: Low heat generation resistor, 3: High heat generation resistor, 4: External connection terminal, 5: Conductor, 7, 8: Through hole, 10: Ceramic heater, 11a to 11e: Water level detection Electrodes, 12: container, 13: inner lid, 65: second control unit, 66: first control unit.

Claims (1)

[Claims] 1. A container for containing water, a low heat generation resistor and a high heat generation resistor for heating the water in the container, the temperature detection unit for detecting the water temperature, and the water in the container When the temperature reaches a complete boiling temperature, the high-heat generating resistor is turned off by a signal output from the temperature detecting unit, and the first control unit is turned on when the water temperature is boiling and is below the operation lower limit temperature, and the water in the container is When the temperature reaches the complete boiling temperature, the low heat generating resistor is turned off at the same time as the high heat generating resistor by the signal output from the temperature detecting unit, and after the high heat generating resistor is turned off, the boiling water operation lower limit temperature An electric pot, comprising: a second controller for turning on and off the low heat-generating resistor within a predetermined temperature range between the temperature and the complete boiling temperature.