JPS6351002B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a boiling water type electric pot, and more specifically, it is an electric pot that boils water for a predetermined period of time and then maintains it at a predetermined temperature below the boiling point. This invention relates to a boiling water type electric pot equipped with a cooking prevention function.

<Prior art> For example, as shown in FIG. 4, a conventional electric pot has a main heater 96, a thermostat 97, and a temperature fuse 73 connected in series between both terminals of a commercial AC power source 70. It has a configuration in which a series circuit of a heat retention heater 98 and a heat retention thermostat 99 is connected in parallel with the thermostat 97, and the thermostat 97 is turned on until the water temperature inside the electric pot reaches 94 to 96 degrees Celsius. By energizing only the main heater 96, the temperature of the hot water is rapidly increased, and after reaching 94 to 96°C, the temperature of the hot water is prevented from decreasing mainly due to the heat generated by the insulating heater 98.

An electric kettle with such a configuration has the advantage of being able to maintain the water temperature at a predetermined temperature close to the boiling point after a predetermined period of time has elapsed, but the water never reaches the boiling point. It doesn't boil, so
Especially at the beginning of the heat retention state, the smell of limescale,
There are problems such as chlorine odor etc. not being completely removed, and the general public's lifestyle habits leaving them feeling dissatisfied with hot water that does not boil.

Recently, in order to solve such problems, as shown in FIG. 5, a boiling water heater 5 and a timer switch 102,
and a temperature fuse 73 are connected in series, a timer motor 101 that drives a timer switch 102, and a timer motor 101 that detects a temperature close to the boiling point.
The series circuit of the thermostat 100 that turns on is connected in parallel with the boiling water heater 5, and the timer switch 10
It has a configuration in which a heat insulation circuit 74 is connected in parallel with 2,
At the beginning of heating, only the boiling water heater 5 is energized to rapidly raise the water temperature, and after reaching a temperature close to the boiling point,
The thermostat 100 is turned on, energizing the timer motor 101, and continues energizing the boiling water heater 5 until the timer motor 101 is activated for a predetermined period of time. After the timer motor 101 has been activated for a predetermined period of time, the boiling water heater 5 and the heat retaining circuit 74 are energized to maintain the water temperature at a predetermined temperature slightly lower than the boiling point.
With an electric kettle of this kind of configuration, after boiling water for a predetermined period of time, it continues to be maintained at a predetermined temperature slightly lower than the boiling point, making it possible to completely eliminate chlorine odor, chlorine odor, etc., and eliminate any sense of dissatisfaction. However, after the boiling point is reached, heating by the boiling water heater is uniformly continued for a predetermined period of time, so for example, if only a small amount of water is in the electric kettle. Alternatively, if no water is added at all, the temperature of each component of the electric pot may rise abnormally, and in the worst case, the electric pot may be damaged.

Since such problems are likely to occur frequently in home kitchens, they must be resolved in order to put boiling water type electric pots into practical use.

<Purpose> This invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a boiling water type electric pot which has a function of keeping water warm after boiling and also has a function of preventing dry water from heating. .

<Structure> The structure of the boiling water type electric pot of the present invention to achieve the above object is that the electric pot has an inner container inside the outer case and a heater for heating the liquid at a predetermined position. A control means is provided for energizing only the heater to generate heat until the liquid reaches its boiling point and a predetermined time has elapsed thereafter, and a heat retention means is provided for energizing only the heater and maintaining the temperature of the liquid at a predetermined value after the heat generation time has elapsed. The present invention is further characterized in that it is provided with a dry-cooking prevention means that detects that the internal temperature of the inner container has reached a predetermined temperature higher than the boiling point and immediately cuts off the power supply only to the heater.

<Examples> Hereinafter, examples will be described in detail with reference to the accompanying drawings showing examples.

FIG. 1 is a longitudinal sectional view showing a boiling water type electric pot.

1 is an exterior case, 2 is a stainless steel inner container, 3 is a pouring pipe, 4 is a discharge pipe, 5 is a boiling water heater, and 6 is a lid unit. The outer case 1 has a support 11 for supporting the middle container 2 and a socket 13, and further supports a thermistor 82 that is thermally coupled to the middle container 2, a timer 17, and an upper end flange 22 of the middle container 2. It has an inward flange 18. Reference numeral 23 denotes a lid, and the upper end flange 24 is supported by the upper end flange 22 of the inner container 2 with a packing 22a having an appropriate shape such as a U-shape in cross section interposed therebetween. The pouring pipe 3 has a pumping pipe 33 located inside the medium container 2 and a supply pipe 34 located above the lid body 23, and both pipes have a water stop ball 36 inside and penetrate vertically. They are communicated through a connecting pipe 35 having an air passage 37. The discharge pipe 4 is connected to the supply pipe 34 via an auxiliary pipe 44, and the auxiliary pipe 4
The protrusion 45 is attached to the exterior case 1 so as to be movable in the axial direction of the protrusion 4, and has a protrusion 46 that comes into contact with the protrusion 45 to prevent movement in the removal direction. The discharge pipe 4 can be completely removed by pushing the discharge pipe 4 into the hole.

The auxiliary pipe 44 is screwed onto the top plate 19 of the outer case 1.

In addition, the lid unit 6 is a bellows type air pump 6.
2, and has a presser cover 65 for driving the bellows type air pump 62, a spring 66, and a closing member 67,
Furthermore, it has a lock lever 63.

Figure 2 is an electrical circuit diagram, with commercial AC power supply 70
A boiling water heater 5, a relay contact 72 and a temperature fuse 73 are connected in series between both terminals of the relay contact 7.
A heat-retaining circuit 74 as a heat-retaining means is connected in parallel with 2. Then, the commercial AC power source 70 is rectified by a diode 75, smoothed by a capacitor 76 and a voltage regulator diode 77, and made to have a constant voltage to obtain a positive voltage terminal 78 and a ground terminal 79. A cooking prevention means is connected.

The control means includes a comparator 84 to which an inverting input terminal voltage is applied by resistors 80 and 81 and a non-inverting input terminal voltage by a thermistor 82 and a resistor 83 as temperature-sensitive resistance elements, and a resistor 8.
5 and a capacitor 86, and a comparator 89 which receives an inverting input terminal voltage through resistors 87 and 88, and receives an output signal from the comparator 89 as an input. It is composed of a series circuit of a switching transistor 90 for switching and a relay coil 91 for driving the relay contact 72, and the output terminal of the comparator 84 is connected to a connection point 92 between a resistor 85 and a capacitor 86. Note that a negative characteristic thermistor is used as the thermistor 82. Therefore, when the temperature detected by the thermistor 82 is low, the comparator 84 outputs a low level signal, and the comparator 84 outputs a low level signal.
9 outputs a high level signal and energizes the relay coil 91 to turn on the relay contact 72,
By increasing the calorific value of the boiling water heater 5, the temperature of hot water can be raised rapidly. Furthermore, when the temperature of the hot water rises to near the boiling point, the comparator 84 outputs a high level signal, so the capacitor 86 is charged through the resistor 85, and the voltage at the connection point 92 is increased by a time constant determined by the resistor 85 and the capacitor 86. rises at
After a predetermined time delay after the comparator 84 outputs the high level signal, the comparator 89 outputs the low level signal and cuts off the power to the relay coil 91.

In other words, even after the boiling point has been reached, the boiling water heater 5
The heat generated by the water boils the water, and then the temperature of the water is maintained at a predetermined temperature slightly lower than the boiling point by the heat retention circuit 74.

The dry cooking prevention means is provided with an inverted input terminal voltage by the thermistor 82 and the resistor 83,
The output signal of a comparator 95 to which a non-inverting input terminal voltage is applied by resistors 93 and 94 is connected to the base terminal of the switching transistor 90. Therefore, when the temperature detected by the thermistor 82 reaches a predetermined temperature higher than the boiling point, the comparator 95 outputs a low level signal.
By forcibly turning off the switching transistor 90 and turning off the relay contact 72 regardless of the operating state of the control means, it is possible to prevent the dry cooking state. In this case, although not shown, it is preferable to install an indicator such as an LED that lights up in response to the low-level signal output from the comparator 95, so that the empty cooking state can be displayed.

If the boiling water type electric pot with the above configuration is operated with a sufficient amount of water in the inner container, the water will be heated to the boiling point, boiled for a specified time, and then the water temperature will rise. Since the water can be maintained at a predetermined temperature slightly lower than the boiling point, it is possible to reliably remove chlorine odor and chlorine odor, and to give a sense of satisfaction to the user. If the medium container is operated with only a small amount of water or no water at all, the detected temperature will continue to rise even after reaching the boiling point, but it will not rise until the specified temperature. Since it is forcibly switched to the warm state at this point, it is possible to reliably prevent dry cooking and eliminate the inconvenience of component parts being damaged by heat.

FIG. 3 is an electric circuit diagram showing another embodiment,
The difference from the embodiment shown in FIG. 2 is that a positive characteristic thermistor is used as the thermistor 82, and the resistors 87,
8 and comparator 89 are omitted and the connection point 92 is
The only difference is that the output terminal of the comparator 95 is directly connected to the base terminal of the switching transistor 90, and the output terminal of the comparator 95 is connected to the connection point between the switching transistor 90 and the relay coil 91, and the configuration of the other parts is the same. .

Therefore, when the temperature detected by the thermistor 82 is low, the comparator 84 outputs a low level signal, so the base-emitter bias of the switching transistor 90 is large, and the relay coil 91 is energized to rapidly increase the water temperature. can be raised. When the temperature reaches close to the boiling point, the comparator 84 outputs a high-level signal to charge the capacitor 86, so that the base-emitter bias of the switching transistor 90 gradually decreases, and after a predetermined period of time, the relay coil 9
The heat retention operation can be performed by cutting off the power supply to 1.

Further, when a predetermined temperature equal to or higher than the boiling point is reached, the comparator 95 outputs a low level signal, so that the amount of current applied to the relay coil 91 is drastically reduced, and the temperature keeping operation can be forced.

That is, as in the embodiment shown in Fig. 2, if there is a sufficient amount of water in the medium container, it is possible to rapidly raise the temperature to the boiling point, continue boiling water for a predetermined time, and then perform a warming operation. Additionally, when there is only a small amount of water in the medium container or no water at all, dry cooking can be prevented by detecting a predetermined temperature higher than the boiling point and immediately performing a heat-retaining operation.

However, in this case, since the bias of the switching transistor 90 changes continuously, the responsiveness will be somewhat degraded, but this does not seem to be a particular disadvantage.

Note that the present invention is not limited to the above-described embodiments; for example, a circuit that reduces the amount of electricity supplied to the boiling water heater 5 may be used as the heat retention circuit 74, or a circuit that reduces the amount of electricity supplied to the boiling water heater 5 as the heat retention circuit 74 may be used. Heater 5
In addition, it is possible to connect in parallel with the commercial AC power source 70 using a relay contact, and also to provide temperature-sensitive resistance elements in the control means and the heating prevention means separately without sharing them. Install a thermostat that detects abnormal temperature rise in series with the fuse (However, in this case, a relatively large installation space is required and the cost increases.) The amount of water is detected as capacitance, and the It is possible to prevent this, and various other design changes can be made without changing the gist of the present invention.

<Effects> As described above, this invention boils water for a predetermined period of time and then maintains it at a predetermined temperature slightly lower than the boiling point, so it is possible to completely remove chlorine odor, chlorine odor, etc. even in the initial stage of heat retention. It gives you a sense of security and satisfaction knowing that you are keeping the boiling water warm, and if the amount of water in the inner container is small or zero, you can heat it for as long as it should continue boiling. Therefore, it is possible to effectively eliminate the inconvenience of abnormal temperature rise and damage of each component.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing one embodiment of a boiling water type electric pot, Fig. 2 is an electric circuit diagram showing one embodiment of the same, and Fig. 3 is an electric circuit diagram showing another embodiment of the same.
FIG. 4 and FIG. 5 are electrical circuit diagrams showing a conventional example. DESCRIPTION OF SYMBOLS 1...Exterior case, 2...Inner container, 5...Boiling water heater, 74...Heat insulation circuit as heat insulation means, 7
2... Relay contact constituting the control means, 82...
Thermistors 84, 89, which constitute the control means...
Comparator 90 constituting control means...Switching transistor 85 constituting control means
...Resistor forming a delay circuit, 86... Capacitor forming a delay circuit, 95... Comparator forming a heating prevention means.

Claims (1)

[Scope of Claims] 1. In an electric pot that has an inner container inside an outer case and a heater for heating a liquid at a predetermined position, the heater is used only until the temperature of the liquid reaches the boiling point and until a predetermined period of time has elapsed thereafter. In addition to providing a control means for energizing and generating heat, a heat-retaining means is provided for energizing only the heater and maintaining the temperature of the liquid at a predetermined value after the heat generation time has elapsed. A boiling water type electric pot characterized by being provided with a means for preventing dry cooking, which detects this and immediately cuts off the power supply only to the heater. 2. The control means detects a temperature close to the boiling point by a change in the resistance value of the temperature-sensitive resistance element, and delays the boiling point detection signal, which causes only the heater to be energized and stops generating heat, for a predetermined period of time using a delay circuit. A boiling water type electric pot according to claim 1. 3. The boiling water type electric pot according to claim 1, wherein the heat retaining means energizes a heat retaining heater provided separately from a heater for heating the liquid. 4. The boiling water type electric pot according to claim 1, wherein the heat retaining means changes the amount of heat generated by a heater for heating the liquid. 5. The dry heating prevention means detects a predetermined temperature higher than the boiling point by a change in the resistance value of the temperature-sensitive resistance element, and immediately stops energization and heat generation of only the heater. Boiling water type electric pot.