JPH0372286B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pot heater and an electric pot equipped with the same.

(Prior art) Conventionally, electric pots have a structure in which a hole is made through the vacuum layer of a double vacuum container made of metal, and a heater is watertightly inserted into this hole from the outside, or a hole is inserted into the bottom of the double vacuum container. A structure in which the heater is attached from the outside with a part of the inner layer being single-layered, or a structure in which the heater is brazed directly to the bottom of the inner container of a vacuum double container, and an airtight terminal is provided on the outer container to draw out the lead wire. something is known.

(Problem to be solved by the invention) However, the former two have the problem of poor insulation and high power consumption during heat retention, while the latter has good insulation but has poor productivity and is expensive. There were flaws. Further, heaters used in this type of electric pot include mica heaters and sheathed heaters, but these require coating with a metal material due to their structure, and have had problems in corrosion resistance.

Moreover, in order to detect the amount of contents or the water level in these electric pots, a hole is formed at the bottom of the container to communicate with the liquid level display tube.
In addition, an independent water level detection electrode must be installed on the container wall or hung from the opening of the container, which complicates pot manufacturing and assembly. There was a risk that the heater would be energized at a lower temperature than the actual temperature, causing damage to the heater and container due to dry heating.

The present invention was made in view of these problems, and can be installed without drilling or other processing on the container, has excellent corrosion resistance, can be heated efficiently, and can also prevent dry heating and detect water level. The object of the present invention is to provide a heater for a pot.

Another object of the present invention is to provide an electric pot that uses the heater described above to efficiently heat contents, prevents dry heating, and is simple in structure and easy to manufacture.

(Means for Solving the Problems) As a means for solving the problems described above, the present invention provides a heater for pots that includes a plate-shaped, rod-shaped, or tubular ceramic base, and a predetermined length embedded in one end of the base. a resistor, at least a pair of water level detection electrodes installed externally on the base, and connected to the resistor and the water level detection electrode through conductors embedded in the base along the longitudinal direction thereof, respectively. , and a plurality of external connection terminals provided externally on the other end side of the base body.

In one embodiment of the present invention, a resistor embedded in one end of a ceramic base is divided into two parts, a low heat generation resistor and a high heat generation resistor, starting from the one end. In this embodiment, the ends of the first and second resistors are connected to external connection terminals via independent conductors, or
Alternatively, one end of the low heat generation resistor and one end of the high heat generation resistor are internally connected, and the connecting portion is connected to one external connection terminal via a single conductor.

In another embodiment, the water level detection electrode includes two water level detection electrodes arranged externally as a pair at a predetermined distance from one end of the base body,
It is used to detect whether the amount of contents in the pot or the water level has reached the lowest level that will prevent the pot from boiling dry. Further, as the water level detection electrode, a water level detection electrode serving as a reference electrode is provided externally on one end side of the base, and a plurality of water level detection electrodes are arranged at predetermined intervals from the reference electrode in the longitudinal direction of the base to form a pair with the reference electrode. The water level detection electrode may be provided externally, or another water level detection electrode may be provided externally at the same level as the reference electrode.

As a means for achieving the above-mentioned other objects, the present invention provides a plate-shaped, rod-shaped, or tubular ceramic base, a resistor of a predetermined length embedded in one end of the base, and a resistor of a predetermined length buried at the other end of the base than the resistor. at least one pair of water level detection electrodes provided externally at positions closer to the sides; each connected to the resistor and the water level detection electrode via a conductor buried in the base along the longitudinal direction; Using a heater consisting of a plurality of external connection terminals provided externally on the other end side, the heater is suspended into the container from the upper opening of the container,
Further, the container is attached to the upper opening of the container with the other end facing upward. in this case,
The control device that controls the heater includes a heater control unit that is connected to an external connection terminal of the heat generating part of the heater and controls energization of the heat generating part, and a heater control unit that is connected to the water level detection electrode and detects the water level in the container. and a water level detection section that outputs a signal corresponding to the water level to the heater control section, and when the water level detection section detects that the water level is below a predetermined level, it prohibits energization to the heat generating section. It is preferable to output a signal.

Further, the control device includes a display element that displays a water level, and an LED drive unit that drives the display element according to a signal from the water level detection section, and the water level is displayed on the display element according to the signal from the water level detection section. may be displayed. In this case, a plurality of water level detection electrodes are installed externally on one end of the ceramic base at a predetermined interval from each other, and each electrode is externally installed on the other end of the base via a conductor buried in the base. It is preferable to connect to the external connection terminal provided. Therefore, in the present invention, the water level detection electrode is used as an electrode for detecting the amount of liquid in the pot and operating the liquid level display device, and at the same time drives the dry cooking prevention device to control the amount of water in the pot. It is also used as an electrode to prevent dry cooking. Further, as electrodes for preventing dry cooking, only a pair of water level detection electrodes may be formed at a predetermined distance from one end of the ceramic base.

(Function) In the pot heater having the above structure, the heater is suspended from the upper opening of a container containing a liquid, and the other end side of the heater with external connection terminals is placed upward. Easily installed. Therefore, in the electric pot of the present invention, since the heater is in direct contact with the contents, such as water, it contributes to reducing heat loss and improving heating efficiency. In addition, the water level detection electrode provided on the heater is arranged so that it can come into contact with the contents inside the container, such as water, so when the water level is below a predetermined level, it stops energizing the heater and prevents dry heating. Contribute to prevention.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1 showing a pot heater according to the present invention, 1 is a ceramic base, 2 is a low heat generation resistor, 3 is a high heat generation resistor, 4 is an external connection terminal, and 5 is a ceramic base.
are conductors connecting both ends of each resistor and each external connection terminal 4; 11a to 11e are water level detection electrodes provided externally on the base 1; heating resistors 2, 3 and conductor 5 are connected to the ceramic base 1; It is buried in the surface layer to prevent it from coming into contact with water during use. In addition, even if the amount of water in the container decreases, the heating resistors 2 and 3 are buried in one end that will be on the bottom side when installed in the pot, in order to generate convection in the water and heat it evenly above and below. . The external connection terminal 4 is provided externally on the other end side of the base 1.

The pot heater having the above structure can be manufactured, for example, as follows. First, as shown in Figure 2, ceramic material powder is slurried,
A cylindrical main body part 1a is formed using the slurry, while a ceramic sheet 1b is formed, and an ink made of a resistance material is printed on this to form a low heat generation resistor 2.
and a resistive film 2' forming the high heat generating resistor 3,
3' and several conductive films 5' forming conductors as lead wires are formed. Next, the ceramic sheet 1b is wound around the main body part 1a with the surface on which the resistive film is formed facing inside, and the ceramic sheet 1b is baked to integrate them, thereby easily manufacturing the ceramic sheet 1b. The external connection terminals are formed by forming a conductive film 5' on the back surface by drilling a through hole 7 in the ceramic sheet in advance at the position where the external connection terminal is to be formed and applying a conductive paste onto the through hole 7 from the front surface. It is formed by firing and baking this. In addition, water level detection electrodes 11a to 11
In order to form e, a through hole 8 is made in the position where an electrode is to be formed in the ceramic sheet, and a conductive paste is applied from the front surface onto the through hole 8 to make it conductive with the conductive film formed on the back surface. After firing, the conductive film on the through hole 8 is plated with nickel, silver, or other material.

Note that the width of the resistive film 2' is made narrow so as to have a high resistance, and the width of the resistive film 3' is made wide so that it has a low resistance. As the material for forming the resistive films 2', 3' and the conductive film 5', a known conductive paste containing silver, nickel, or tungsten may be used.
In addition, the water level detection electrodes 11b to 11e are used to detect water continuity with the reference electrode and display the amount of water using the level meter 50, and are also used to determine the boiling time depending on the amount of water. ,Also,
Between the electrodes 11a and 11c, a heat-retaining heater 2 is connected between the electrodes 11a and 11b to prevent the main heater 3 from running dry.
Used to prevent dry cooking.

In the above embodiment, the main body part 1a is formed into a cylindrical shape, but it may also be formed into a rod shape.Alternatively, the main part 1a of the base body is formed into a plate shape, and a resistive film and a conductive film are formed on this. After laminating the ceramic sheets 1b, they may be fired. Furthermore, the patterns of the resistive films 2' and 3' may be formed independently as shown in FIG. 5 instead of the pattern shown in FIG.

When using a heater with a water level detection electrode formed in this way, there is no need to form a hole in the bottom of the container to communicate with the liquid level display tube as in the past, and the water level detection electrode can be installed independently on the container wall. There is no need to hang the pot or hang it from the opening of the container, making the pot easy to manufacture and assemble.

FIG. 3 shows an embodiment of an electric pot using the heater 10 having the structure shown in FIG.
12 is a water level detection electrode provided externally to the heater 10;
1 is a metal vacuum double container, consisting of an inner container 12a, an outer container 12b, and an exhaust tip tube 12c, and a vacuum is created between the inner container 12a and the outer container 12b. 13 is a metal inner lid brazed or welded to the upper open end of the vacuum double container 12, and the opening 14
have. The heater 10 has a mounting fitting 15 attached to its upper end, and a bottom 18 that closes the hollow portion of the heater 10 to its lower end.
Further, a temperature sensor 16 is provided in the hollow part of the heater 10.
(see Figure 4), and this sensor is located at the bottom 18.
is fixed. 17 is a micro switch, 1
9 is a supporting metal fitting, 20 is an exterior body, 21 is an exterior bottom, 22 is an exterior shoulder body, 23 is an outer lid, and 20 is an exterior body.
A level meter 50, which will be described later, is attached to the pouring port side of No. 0. The shoulder body 22 has an opening 1 of the inner lid 13.
4, the inner plug 25 is removably inserted.

The inner stopper 25 has a water lift pipe 26 and a water injection pipe 27, and a safety valve 28 is disposed in a flow path that communicates them. Inside the outer lid 23, a bellows 30,
Spring 31, steam cylinder 32, bellows upper plate 33
A bellows pump consisting of a bellows pump is installed inside, and a valve body 35 for opening and closing the exhaust port 34 of the bellows pump is installed outside at 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 of the bellows exhaust pipe 39 may also be used as the valve seat.
Since the upper end of the steam cylinder 32 is fixed to an intake cylinder 40 formed on the bellows upper plate 33, the valve body 35 is brought into close contact with the valve seat 38 by the action of the spring 31. A gasket 41 is fitted to the intake cylinder 40 of the bellows upper plate 33, and the gasket 41 and the cap 42 open and close the intake hole 43. is biased upward by. 45 is a steam hole, and 46 is a pusher body.

The electric pot according to the present invention includes a heater control circuit,
It is equipped with a control device 51 consisting of a liquid level display device and an empty cooking prevention device. As shown in FIG. 4, this control device includes a pulse generator 53, a water level detector 54, a heater controller, a display element 61 that displays the water level, and an LED driver 60 that drives the display element. It mainly consists of

The pulse generator 53 generates a pulse voltage, for example, a pulse voltage having a pulse output period of 1 ms and a rest period of 4 seconds, and applies the pulse voltage to the water level detection electrode 11a serving as a reference electrode and other water level detection electrodes. 1
1b to 11e, and the water level detection unit 54
Other electrodes 11 each pair with the reference electrode 11a
The water level is detected by the conduction or non-conduction between b to 11e, and a signal corresponding to the detected water level is output.

The heater control section includes a temperature sensor 16 attached to the bottom of the heater 10, a temperature detection section 59 that detects the temperature based on a signal from the temperature sensor 16, and a triact trigger section 57 that controls energization to the low heat generation resistor 2. It consists of a first control circuit and a second control circuit including a triact trigger section 58 that controls energization to the high heat generation resistor 3. Controls energization to the heat generating resistor 3. The first control circuit includes a triax 55 connected in series to the low heat generation resistor 2,
The second control circuit includes a triax 56 connected in series to the high heat generating resistor 3.

The LED driving section 60 drives each element 61 of the level meter 50, which functions as a display element, according to the output signal from the water level detection section 54. In addition, in order to prevent electric shock in case the heater is damaged, etc., there is a voltage detection section 62 that detects the voltage of the container 12, and a power supply intermittent section 63 that turns off all circuits based on the output signal from the voltage detection section 62.
is included. Additionally, a microswitch 17 is provided at the bottom of the pot to turn off the power if the pot is lifted or tipped over.

When using the electric pot configured as described above, after filling the container 12 with cold water, inserting the plug 70 and turning on the electricity, the high heat generating resistor 3 or together with the low heat generating resistor 2 will boil water. , When boiling is performed after a predetermined period of time, a signal from the temperature sensor 16 energizes the high heat generation resistor 3 (if the low heat generation resistor 2 is used together, the low heat generation resistor 2 and the high heat generation resistor 3 are energized). After that, only the low heat generation resistor 2 is activated by the output signal from the temperature sensor 16 to maintain the temperature. In addition, when conventional electric pots are boiled, steam enters the bellows and deforms the bellows, making it unusable, so the maximum temperature is 95°C.
In the illustrated example, a steam cylinder 32 is provided that passes through the bellows 30, and a valve body 35 prevents steam from entering the bellows 30. The problem is solved by discharging it to the outside through the hole 45.

Further, the water level detection section 54 includes the water level detection electrode 11
A signal is output depending on whether there is conduction or non-conduction due to water between b to 11e and the reference electrode, and the output signal causes the water level display level meter 50 to display the amount of water, and also determines the boiling time according to the amount of water. Also, between the electrodes 11a and 11c, the electrode 11a is used to prevent the high heat generation resistor 3 from drying out.
The space between and 11b is used to prevent the low heat generation resistor 2 from running dry. That is, when the water level decreases to a level below the electrode 11c, the water level detection section 54 outputs a trigger prohibition signal to the triact trigger section 58 to stop energizing the high heat generation resistor 3, and the water level further decreases. When the level becomes lower than the electrode 11b, a trigger prohibition signal is also output to the triat trigger section 57 to stop energizing the low heat generation resistor 2 as well. Therefore, dry firing will not occur.

(Effects of the Invention) According to the present invention, since the heat generating part of the heater is embedded in the ceramic base, the heater can be suspended from the upper opening of the container containing the liquid and connected to the outside. The heater with external terminals can be installed with the other end facing up.
Because the heater is in direct contact with the contents, e.g. water,
Heat loss is small and thermal efficiency can be significantly increased. Moreover, since there is no need to perform hole drilling or other processing on the container for attaching the heater, the number of manufacturing steps for the container can be reduced, the pot assembly is easy, and the container can be manufactured at low cost. Furthermore,
By using not only a metal vacuum double container but also a glass vacuum double bottle as the container, the heat retention property is significantly improved, and the power consumption required for heat retention can be extremely reduced. In addition, since a water level detection electrode is formed on the heater, it is possible to detect the water level inside the container, and when the water level is below a predetermined level, the power to the heat generating part of the heater can be stopped. , therefore, there is no fear of dry heating, and other excellent effects are achieved.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway view of a pot heater according to the present invention, FIG. 2 is a perspective view of the manufacturing process, FIG. 3 is a cross-sectional view showing an example of the electric pot according to the present invention, and FIG. The block diagram of the circuit, FIG. 5, is a developed view showing a modification of the resistor forming portion of the heater. DESCRIPTION OF SYMBOLS 1...Ceramic base, 2...Resistor for low heat generation, 3...Resistor for high heat generation, 4...External connection terminal, 5...Conductor, 7, 8...Through hole, 10...
Heater, 11a to 11e... Water level detection electrode, 1
2... Container, 13... Inner lid.

Claims (1)

[Scope of Claims] 1. A plate-shaped, rod-shaped, or tubular ceramic substrate; a resistor of a predetermined length embedded in one end of the substrate; and at least a pair of water level detection electrodes provided externally on the substrate; A plurality of external connection terminals are connected to the resistor and the water level detection electrode through conductors embedded in the base along the longitudinal direction thereof, and externally provided on the other end of the base. A pot heater featuring: 2. The resistor is divided into two parts, a low heat generation resistor and a high heat generation resistor, and the low heat generation resistor and the high heat generation resistor are formed in this order from one end of the base to the other end. A pot heater according to claim 1. 3 One end of the low heat generation resistor and one end of the high heat generation resistor are connected inside the base, and the connection part is 1
3. The pot heater according to claim 2, wherein the pot heater is connected to one of the external connection terminals via a strip of conductor. 4. The pot according to claim 1, 2, or 3, wherein the water level detection electrode is two water level detection electrodes installed at a predetermined distance from one end of the base. heater. 5. The water level detection electrodes include a water level detection electrode that serves as a reference electrode provided externally on one end side of the base, and a plurality of water level detection electrodes provided externally at predetermined intervals in the longitudinal direction of the base from the reference electrode, and the reference electrode and the reference electrode. A pot heater according to any one of claims 1 to 4, comprising a plurality of water level detection electrodes each forming a pair. 6. An electric pot consisting of a container containing a liquid, a heater that heats the liquid in the container, and a control device that controls energization of the heater, in which the heater is formed of a plate-shaped, rod-shaped or tubular ceramic substrate. ,
a resistor of a predetermined length embedded in one end side of the base;
The resistor and water level are detected through at least one pair of water level detection electrodes externally provided at a position closer to the other end of the base than the resistor, and a conductor embedded in the base along its longitudinal direction. and a plurality of external connection terminals externally provided on the other end of the base, the heater being suspended into the container from the upper opening of the container, and connected to the other end of the container. An electric pot, characterized in that it is attached to the upper opening of the container with the pot facing upward.