JPH0380486B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a liquid heating container, and more specifically, to a liquid heating container having an empty cooking prevention function.

<Prior art> Conventionally, an inner container was provided inside the outer case, and a heating element was further provided at the bottom of the inner container so that the water inside the inner container could be boiled or kept at a high temperature. A so-called electric pot is known as a liquid heating container.

In such electric pots, since the heating element is provided while being immersed in water or hot water, the watertight structure becomes complicated in consideration of electrical insulation, and there is a tendency for the pot to become large. It is also known that a heating element is attached to the outside of the inner container, but because of indirect heating, there are some problems in terms of thermal efficiency compared to direct heating.

Taking these points into consideration, the patent applicant in question:
We have filed a patent application for a liquid heating container that has a ceramic heater integrated with the pouring pipe, but if the internal temperature rises above the optimal water temperature setting or if the internal temperature rises abnormally ( (dry cooking)
However, there was a problem in that the ceramic heater was directly energized.

<Purpose> The present invention improves heating efficiency by providing an inner container of a ceramic heater inside, and by providing a temperature sensor near the ceramic heater to accurately and quickly detect temperature changes and effectively prevent dry cooking. Alternatively, the purpose is to effectively control the temperature of the water, and to further improve safety by locating the ceramic heater below the level of the water that can be pumped up to prevent dry cooking.

<Structure> In order to achieve the above object, the liquid heating container of the present invention has an inner container inside an outer case and a spouting pipe inside the inner container. A temperature sensor is provided at the lower end of the pouring pipe, and a ceramic heater for heating the liquid is placed above the temperature sensor in the pouring pipe. It is characterized by being located below the water level that can be pumped up by the pouring pipe.

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

FIG. 1 is a longitudinal sectional side view showing an embodiment of an electric pot as a liquid heating container.

1 is the outer case of the electric pot, 2 is the middle container made up of a double vacuum bottle, 3 is the pouring pipe inserted into the middle container 2, and 4 is connected to the pouring pipe 3. 5 is a ceramic heater, and 6 is a lid unit provided on the upper part of the outer case 1 so as to be openable and closable.

To explain in more detail, the outer case 1 is formed into a cylindrical shape with a predetermined diameter, and a support 11 for supporting the inner container 2 is fitted into the lower end opening in a locking manner, and the support 11 is attached to a seat. It is rotatably supported on 12. In addition, 13 is a socket for connecting to a power line, 14 is a magnetic plug, and 15 is fitted into the upper end opening of the cylindrical body to immovably support the upper end opening of the inner container 2. It is a lower mouth member. Further, 16 is a means for maintaining the switching element in a state where the ceramic heater is cut off.

The discharge pipe 4 passes through a predetermined position of the lower mouth member 15, and has one end facing the central opening of the lower mouth member 15 and the other end facing the outside of the lower mouth member 15. However, for the part facing the central opening, a downwardly curved pipe 41 is provided, and a connecting pipe 43 is provided that communicates the discharge pipe 4 and the downwardly curved pipe 41, so that the pouring pipe 3 can be easily attached. I have to.

The pouring pipe 3 is a cylindrical body made of ceramic, and its upper end is fitted into the downwardly curved pipe 41, and the lower end is positioned slightly above the inner bottom surface of the medium container 2.

Then, as shown in FIG. 2, a temperature sensing element 53 as a temperature sensor is formed by integrally sintering a temperature sensing resistor 52 between a ceramic layer 51 at the lower end of the pouring pipe 3. A ceramic heater 5 is formed by integrally sintering a resistor 54 between ceramic layers 51 above the element 53, and a pumping hole 3 penetrating the side wall of the spouting pipe 3 is formed slightly above the ceramic heater 5.
2 are provided. Further, a bottom wall is provided at the lower end of the pouring pipe 3, and a drain hole 38 is provided in this bottom wall.

Note that 56 and 57 are lead wires buried in the side wall of the pouring pipe 3. The lead wire 56 electrically connects the socket 13 and the ceramic heater 5, and the lead wire 57 connects the temperature sensing element 53. and a control circuit to be described later.

However, although the lead wires 56 and 57 are buried in the pouring pipe 3 at equal intervals, the lead wires 56 and 5
The lead wires 56 and 57 are brought close to each other at the portion where the lead wires 56 and 57 are pulled out from the spouting pipe 3, and furthermore, at the portion where the lead wires 56 and 57 are pulled out, the lead wires 56 and 57 are connected to the spouting pipe 3. Waterproof band 39 made of rubber etc. that is held integrally
has been established. Furthermore, the lead wires 56 and 57 are covered with silicone rubber.

The lid unit 6 includes a stopper 61 that closes the upper end opening of the medium container 2, a bellows type air pump 62,
The lock lever 63 is connected to the lower mouth member 15 at the rear end (right side in FIG. 1) so as to be vertically movable.

Note that 64 and 65 are presser lids, the presser lid 64 is located at the center opening of the presser lid 65, and the spring 66
The upper end opening of the bellows type air pump 62 is opened by being pushed up by the inner container 2.
This is to prevent abnormal pressure rise inside the tank.

FIG. 3 is an electrical circuit diagram of an electric pot, in which the output terminal of a comparator 74 is supplied with a reference voltage by fixed resistors 71 and 72, and a comparison voltage is supplied by a fixed resistor 73 and a temperature sensing element 53. A reset switch 75 and a relay coil 77 are connected in series. Then, a normally closed terminal 78 driven by the relay coil 77 is connected in series with the temperature sensing element 53,
Another normally closed terminal 79 is connected in series with the ceramic heater 5, and a normally open terminal 80, an alarm element 81 such as a buzzer, and a reset switch 76 are connected in series.
The temperature sensing element 53 has a positive resistance-temperature characteristic, and the reset switches 75 and 76 are normally closed switches that operate in conjunction with each other.

The operation of the electric pot having the above configuration is as follows.

Open the lid unit 6 and pour water into the inner container 2, then insert the magnetic plug 14 into the socket 13.
When inserted, the ceramic heater 5 can be energized to heat and raise the temperature of water. Therefore,
After energizing the ceramic heater 5 for a predetermined time, the lid 6 is closed.
By pushing down the presser lid 64 with the 5, the bellows type air pump 62 is activated, and thereby the hot water in the inner container 2 can be taken out to the outside through the pouring pipe 3 and the discharge pipe 4, making it extremely easy to use. It's a good electric pot.

In addition, if hot water is taken out, the amount of hot water inside the middle container 2 will decrease, but if the pumping hole 32 of the spout pipe 3 is exposed above the hot water level, the bellows-type air pump 62 will Since the internal pressure increase inside 2 is released into the atmosphere from the pumping hole 32 through the pouring pipe 3 and the discharge pipe 4, the hot water level does not drop any further and the ceramic heater 5 is kept immersed in the hot water. , the pouring pipe 3, the downwardly curved pipe 41, the stopper 61, etc. can be prevented from abnormally rising in temperature.

The above is normal operation, and empty cooking can be reliably prevented.

If the ceramic heater 5 is energized without any water being placed inside the inner container 2, the container will be in an empty state, and the temperature detected by the thermosensor 53 will be 100° C. or higher.

Therefore, the comparator 74 energizes the relay coil 77 to cut off the energization to the ceramic heater 5, and energizes the alarm element 81 to notify the abnormal state.

However, in this case, since the normally closed terminal 78 is turned OFF by energizing the relay coil 77,
Even if the temperature detected by the temperature sensing element 53 decreases, the relay coil 77 is energized intermittently, and the ceramic heater 5 is maintained in the energized state.

Further, in order to release the current cut-off state of the ceramic heater 5, the reset switch 75 may be temporarily turned OFF by manual operation. In this case, if you forget to add water, turn on the reset switch 7.
If 5 is operated, the dry cooking state will occur again, so that the power to the ceramic heater 5 can be cut off and the alarm element 81 can be activated in the same way as described above.

According to the embodiment described above, the temperature sensing element 53 as a temperature sensor is provided at the lower end position of the pouring pipe 3 whose lower end faces near the bottom of the medium container 2, and the temperature sensing element 53 of the pouring pipe 3 is provided at the lower end position. Since the ceramic heater 5 is provided above the heating element 53 and below the pumping hole 32 of the pouring pipe 3, the inner container 2
It is possible to reliably detect the temperature of the hot water remaining at the bottom of the boiler to ensure that it does not overcook. Furthermore, even in a state where the pumping hole 32 is above the hot water level and the hot water cannot be taken out, the ceramic heater 5
It is possible to effectively prevent dry cooking by keeping the food immersed in hot water. Furthermore, once the dry heating condition is detected, the ceramic heater 5 can be kept in the energized state unless the reset switch is operated, so safety is extremely high.

Furthermore, since the ceramic heater 5 is provided directly above the temperature sensing element 53, and the ceramic heater 5 directly heats and the temperature sensing element 53 performs direct sensing, it is possible to maintain high heating efficiency and improve temperature change detection performance. It is possible to accurately and quickly sense temperature changes and reliably control the liquid temperature.

In addition, since the ceramic pipe itself that constitutes the pouring pipe 3 also serves as a mounting means for the temperature sensing element 53 and the ceramic heater 5, there is no need to provide a special mounting means, and the installation is easy. play.

Further, in the above embodiments, no mention is made of the size relationship between the pumping hole 32 and the drain hole 38. However, if the drain hole 38 is larger than the pumping hole 32, when the bellows type air pump 62 is driven to increase the internal pressure of the medium container 2, a considerable amount of hot water will flow from the drain hole 38 to the spout pipe 3 and It will be taken out through the discharge pipe 4. Then, there is a risk that the ceramic heater 5 may take out hot water to the point where it is located above the water surface, causing a dry cooking condition.

Therefore, the above problem can be solved by closing the lower end of the spouting pipe 3, but when the spouting pipe 3 is removed, the hot water inside the spouting pipe 3 must be removed. This makes it difficult or almost impossible to remove water from the drain hole 38.
It is preferable that the size of the hole is smaller than the pumping hole 32 and has a predetermined diameter that is not so small as to interfere with the draining operation.

FIG. 4 is an electric circuit diagram showing another embodiment,
Zero volt switch 83 by resistors 71 and 72
A reference voltage is applied to the non-inverting input terminal 4 of the (Kyocera Corporation μPC1701C), and a comparison voltage is applied to the inverting input terminal 3 of the zero-volt switch 83 through the temperature sensing element 53 and the resistor 73, and the pulse output terminal of the zero-volt switch 83 is applied. The pulse signal from 6 is applied to the gate terminal of triac 82, and ceramic heater 5 is connected in series with triac 82. Then, connect the comparator output terminal 2 to the resistor 7
It is connected to 1,72 connection points.

Therefore, according to this embodiment as well, it is possible to detect the dry cooking state, prevent the dry cooking state, and maintain the state in which the power supply to the ceramic heater 5 is cut off after the dry cooking state is detected.

FIG. 5 is a central vertical cross-sectional view showing the relationship between the spouting pipe 3 and the temperature sensor 53. The difference from the embodiment shown in FIG. These are only the points provided and the configuration of the temperature sensor 53.

That is, in this embodiment, the temperature sensor 53 is
It is composed of a thermal reed switch that switches at a predetermined temperature as a critical value, a thermally responsive displacement switch, a shape memory alloy switch, etc., and the sealed box 53a
It is supported on the bottom wall of the pouring pipe 3 provided with a drain hole 38 while being built into the ceramic heater 5, and also serves as a switching element for controlling the supply of electricity to the ceramic heater 5. Then, the lead wire 57 drawn out from the sealed box 53a is covered with silicone rubber or the like, and a waterproof band 53b made of rubber or the like is provided to integrally hold the lead wire 57 and the sealed box 53a, thereby performing waterproof treatment. , the lead wire 57 is passed through an insertion hole (not shown) formed at the upper end of the spouting pipe 3 or at a predetermined position of the connecting pipe 43.
is pulled out to the outside of the middle container 2.

Here, a packing (not shown) is interposed in the insertion hole to prevent leakage of water or hot water. Furthermore, legs 53c are formed on the lower surface of the sealed box 53a to prevent the drain hole 38 from being blocked. However, it goes without saying that a switching element for controlling energization to the ceramic heater can be provided separately.

Therefore, similarly to the above-mentioned embodiments, it is possible to detect the dry cooking state, prevent dry cooking, and maintain the state in which the power supply to the ceramic heater 5 is cut off after the dry cooking state is detected.

FIG. 6 is an electrical circuit diagram of an embodiment using a microcomputer, with fixed resistors 7 connected in series.
3 and the temperature sensing element 53, the connection point voltage V2 of the variable capacitor 85, which is composed of a series-connected capacitor 84, and a pair of electrodes (not shown) sandwiched between the side walls of the inner container 2. of,
input to the CPU 87 through the I/O port 86,
Furthermore, a gate terminal of a triax 82 which controls the energization to the ceramic heater 5 and a switching transistor 88 which controls the energization to the alarm element 81 are provided.
The output signal of the CPU 87 is applied through the I/O port 86 to the base terminal of the LED array 89 and the control terminal of the drive circuit 90 that drives the LED array 89. In addition, the CPU87 has ROM, RAM,
Built-in CLOCK etc.

The operation in this case is as shown in the flowchart in FIG. Determine whether or not. If the amount can be pumped up, it is determined in step whether the temperature of the water or hot water has reached the set temperature, and if it has reached the set temperature, the power to the ceramic heater 5 is cut off in step, If the step has not been reached, the operations below the step are repeated again.

Further, in the step, if it is determined that the amount of water or hot water is not the amount that can be pumped up, the power to the ceramic heater 5 is cut off in the step, and the alarm element 8 is activated in the step.
By driving 1, it is possible to reliably prevent dry cooking, and to notify that the amount of water or hot water has decreased. After that, in the step, it is determined again whether the amount of water or hot water inside the inner container 2 has reached the amount that can be pumped up, and if it has not reached the amount, the power supply to the ceramic heater 5 is interrupted and the alarm element 81 is activated continue. When you hear the alarm and pour water or hot water into the middle container 2, it is determined in step that the amount of water or hot water in the middle container 2 has reached the amount that can be pumped up, so the driving of the alarm element 81 is stopped in step. Then, repeat the operations below step again.

That is, when there is sufficient water or hot water in the middle container 2, the ceramic heater 5 is energized or de-energized in accordance with the temperature detected by the temperature sensor 53, so that the hot water is always set. It can continue to maintain the temperature. However, if there is only a small amount of water or hot water in the middle container 2, the alarm element 81 is activated to call attention to it, and the power to the ceramic heater 5 is cut off to ensure that dry cooking is prevented. be able to.

Therefore, when resetting the current cut-off state to the ceramic heater 5, it is sufficient to simply pour water or hot water into the inner container 2, and unlike when resetting manually, it is possible to reset the state with a small amount of water or hot water. The inconvenience of doing so can be completely eliminated.

FIG. 8 is an electric circuit diagram showing still another embodiment, which differs in that a current relay 91 is connected in series with the temperature sensor 53.

More specifically, the normally open terminal 92 of the current relay 91 is connected in series with the ceramic heater 5,
Another normally open terminal 93 is connected in series with the current relay 91, a normally closed terminal 94 is connected in series with the alarm element 81, and a manually operated normally open reset switch 75 is connected in parallel with the normally open terminal 93. A normally closed reset switch 76 is connected in series with a normally closed terminal 94. Note that the reset switch 76 is configured to operate in conjunction with the reset switch 75.

Therefore, when the reset switch 75 is turned on, the current relay 91 is self-held by the normally open terminal 93, and the ceramic heater 5 is energized through the normally open terminal 92 to heat the water inside the inner container 2. The temperature can be raised.

Also, the water level in the middle container 2 is lower than the ceramic heater 5.
If the temperature becomes lower, the temperature detected by the temperature sensor 53 becomes 100°C or more, the resistance value of the temperature sensor 53 increases, and the current value flowing to the current relay 91 becomes less than the critical value, so the normally open terminal 92 turns OFF. At the same time, the power to the ceramic heater 5 is cut off, and the normally closed terminal 94 is turned on to activate the alarm element 81.

Since the normally open terminal 93 is turned OFF at the same time, the ceramic heater 5 is maintained in a state where the current is cut off, and even if the temperature detected by the temperature sensor 53 decreases, the ceramic heater 5 is not energized. In order to release the current cutoff state to the ceramic heater 5, it is sufficient to turn on the reset switch 75.
Heating and temperature raising can be performed in the same manner as above.

Incidentally, the liquid heating container of the present invention is not limited to the above-mentioned embodiment at all, and a dry cooking prevention sensor and/or a temperature control sensor can be used as the temperature sensor. When a ceramic heater is installed, it is possible to make the spout pipe removable together with the discharge pipe, and it is also possible to use a metal medium container instead of the vacuum double bottle, and even to remove the top of the spout pipe. It is also possible to use a stainless steel pipe and the remaining part to be a ceramic pipe. Further, the liquid heating container is not limited to the electric pot described in the above embodiment, but may be a dispensing pipe made by integrally sintering a ceramic heater and a temperature sensor into a dispensing pipe of a conventionally known thermos flask, or other types. Of course, various design changes can be made without changing the gist of the invention.

<Effects> As described above, the liquid heating container of the present invention is provided with a temperature sensor at the lower end position of the spouting pipe whose lower end faces near the bottom of the medium container, and a temperature sensor of the spouting pipe. A ceramic heater for heating the liquid is installed above and below the level of the water that can be pumped up by the pouring pipe, so it reliably senses the temperature of the liquid remaining at the bottom of the inner container and prevents dry cooking. In addition, even when the liquid cannot be removed, the ceramic heater can be kept immersed in the liquid, effectively preventing dry cooking, and is highly safe.
Furthermore, since the ceramic heater is provided near the upper part of the temperature sensor, temperature changes can be sensed accurately and quickly to ensure liquid temperature control.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of the liquid heating container of the present invention, FIG. 2 is a partially cutaway perspective view of the pouring pipe 3, and FIG. 3 is an electric circuit diagram of the liquid heating container.
FIG. 4 is an electric circuit diagram showing another embodiment, FIG. 5 is a vertical cross-sectional view of a main part of the pouring pipe 3 supporting the temperature sensing element 53, and FIG. 6 is a diagram showing another embodiment of the liquid heating container. FIG. 7 is a flowchart, and FIG. 8 is an electric circuit diagram showing another embodiment. DESCRIPTION OF SYMBOLS 1...Exterior case, 2...Inner container, 3...Output pipe, 5...Ceramic heater, 32...Sumping hole, 53...Temperature sensing element as a temperature sensor, 77
... Normally closed terminal as a holding means, 79 ... Normally closed terminal as a switching element.

Claims (1)

[Claims] 1. In a liquid heating container that has an inner container inside an outer case and a dispensing pipe inside the inner container, the lower end of the dispensing pipe faces near the bottom of the inner container, and the temperature sensor is installed as described above. A ceramic heater for heating the liquid is provided at the lower end of the outlet pipe and is located above the temperature sensor of the outlet pipe and below the pumpable water surface of the outlet pipe. Liquid heating container.