JPH0847454A - Electric pot - Google Patents

Abstract

PURPOSE:To carry out heating according to a specified heating-up characteristic by a method wherein heating is weakened or stopped when detected temperature of a container reaches a specified temperature zone prior to boiling, heating state is restored after the detected temperature drops to a specified temperature and the heating-up characteristic of liquid contained is judged to set subsequent heating conditions. CONSTITUTION:A heating controller 24 performs controls based on temperatures detected by a temperature sensor 15 so that liquid contained is heated up to a specified temperature. When rite temperature detected by the temperature sensor 15 reaches a specified temperature zone prior to boiling, heating us weakened or stopped by a first heating regulator 25, and when the temperatures detected by the temperature sensor 15 drop below a specified temperature, not-mal heating is restored again. When the temperatures detected by the temperature sensor 15 return to the specified temperature after the first heating regulator 25 operates, a second heating regulator 26 judges a heating-up characteristic of liquid contained according to changes in temperature detected by tire temperature sensor 15, and subsequent heating conditions are set corresponding to the judged results.

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 for heating a content liquid in a container made of a heat-defective conductor by a heater outside the container.

[0002]

2. Description of the Related Art Such an electric pot is, for example, a so-called milk preparation pot which is boiled once and then kept at a temperature of about 40.degree. Has been applied to.

This product uses a transparent single glass container, and has the advantages that the state and amount of the content liquid can be seen and that it can be easily kept clean. The container made of heat-resistant glass is relatively thick especially at the bottom in order to make it robust and easy to handle.

[0004]

However, if the glass container is a poor heat conductor and the bottom is thick, the heat conduction characteristics are large when the temperature of the container itself is low and when it is high. There is a difference. Therefore, if the heating by the heater is controlled only by the temperature information from the temperature sensor that abuts on the glass container and detects the temperature of the glass container as in the conventional case, the control based on the actual content liquid temperature cannot be performed, and the setting cannot be performed. The control failure such as falling below or exceeding the heating characteristics caused by insufficient heating does not allow sufficient sterilization and descaling due to boiling of the content liquid, or excessive heating causes a risk of overheating. Or

Further, even if the temperature sensor detects the temperature of the bottom made of glass, the temperature of the content liquid heated through the bottom of the glass container in which the heat conduction state is not uniform due to the difference in the temperature range as described above. In addition to not responding correctly to the temperature, the temperature-sensitive characteristics of the temperature sensor are not linear with respect to temperature rise, and if heating by the heater is continued until the content liquid reaches a boiling state, the temperature sensor In some cases, the temperature of the bottom portion of the glass container, which increases in temperature early, may cause an overshoot, which may result in incorrect heating control based on the temperature detected by the temperature sensor.

An object of the present invention is to solve the above problems, and to provide an electric pot capable of heating the content liquid in accordance with a predetermined temperature rising characteristic based on the temperature detected by the temperature sensor. It is the main purpose.

[0007]

The electric pot of the present invention comprises:
In order to achieve the above object, an electric pot for heating the content liquid in a container made of a poorly heat-conductive conductor by a heater outside the container, and a temperature sensor for detecting the temperature of the container and a detection by this temperature sensor. Heating control means for heating and controlling the content liquid to a predetermined temperature based on the temperature, and when the temperature detected by the temperature sensor reaches a predetermined temperature range before boiling, heating is temporarily weakened or stopped, and the temperature sensor is used. A first heating adjusting means for returning to a normal heating state again after the detected temperature is lowered to a certain temperature below the predetermined temperature;
When the temperature detected by the temperature sensor returns to the predetermined temperature after the first heating adjustment means has worked, the temperature rise characteristic of the content liquid is determined from the change in temperature detected by the temperature sensor, and the temperature rise characteristic determination result The main feature of the present invention is to include a second heating adjusting means for setting the subsequent heating conditions according to the above.

The second heating adjusting means can set the time period during which the heating control means maintains the normal heating state, and the change in the temperature detected by the temperature sensor is a predetermined value near the boiling point of the content liquid. It is also possible to set the subsequent heating duration when the temperature rising characteristic of No. 1 is reached.

[0009]

According to the above-mentioned constitution which is the main feature of the electric pot of the present invention, basically, by the function of the heating control means, the content liquid in the container made of the heat-defective conductor is heated by the heater outside the container. Based on the temperature of the container detected by the temperature sensor, heating control is performed so that the content liquid reaches a predetermined temperature. However, in this basic heating control, when the temperature detected by the temperature sensor reaches a predetermined temperature range before boiling, the first heating adjusting means operates to weaken or stop heating once, and the temperature detected by the temperature sensor is After cooling down to a certain temperature below a predetermined temperature, it is returned to the normal heating state again to suppress the overshoot of the temperature-resistance characteristics due to the temperature rise of the container of the temperature sensor by cooling during this period, and it is composed of a heat-defective conductor. While keeping the correlation between the heat conduction characteristic and the content liquid temperature accompanying the temperature rise of the container, the temperature detected by the temperature sensor by the temperature sensor returned to the predetermined temperature after the first heating adjusting means worked. At this time, the second heating adjustment means operates to determine the temperature rising characteristic of the content liquid from the change in the temperature detected by the temperature sensor. The temperature rise-resistance characteristic of the sensor and the content liquid temperature are properly matched, and the second heating adjusting means sets the subsequent heating conditions according to the determination result of the temperature rise characteristic. , The content liquid is adapted to the preset heating state without being affected by the fact that the heat conduction characteristic differs depending on the temperature range of the container which is a poor heat conductor and the temperature-resistance characteristic of the temperature sensor is not stable. be able to.

Even if the second heating adjusting means sets the time for which the normal heating state is maintained by the heating control means, or the change in the temperature detected by the temperature sensor is a predetermined temperature rise near the boiling point. Even if the heating duration is set after that, the final adjustment to the predetermined heating state is started from the proper heating state detection state, so the predetermined heating state can be obtained without error. To be

[0011]

EXAMPLES The electric pot of the present invention will be specifically described below with reference to some examples.

1 to 4 show a first embodiment in which the present invention is applied to an electric pot for formulating milk.

As shown in the overall structure of the electric pot of this embodiment, a heat-resistant glass container 3 is detachably placed on a base 2 having a heater 1 built therein, and the container 3 The content liquid in the inside can be heated by the heater 1. This heating is a sanitary condition that can be used anytime for preparing milk after it has been boiled surely and sufficiently to achieve sterilization and descaling, and then kept warm at, for example, about 40 ° C, which is optimum for infant preparation. Make it possible to supply the content liquid at an appropriate temperature.

The base 2 is composed of a resin bottom member 2a and a resin frame member 2b covering the bottom member 2a from above. The bottom member 2a and the frame member 2b may be appropriately fixed by force fitting or screwing, but it is convenient for repair if they can be disassembled. In this embodiment, the central opening 2 of the frame member 2b
An aluminum heating plate 4 having a built-in heater 1 is arranged in c, and a stainless steel heat shield plate 5 is applied from below so as to extend along the lower surface of the heating plate 4 and the periphery thereof, and the heating plate 4 and the screws. The heat-shielding plate 5 is integrated by a stopper or the like, and the downward flange 5a formed on the outer peripheral portion of the heat-shielding plate 5 is attached to the central opening 2
Both of them, or the heat shield plate 5, the frame member, are positioned by fitting them into the recessed groove 2d formed on the upper surface of the mouth edge of c and screwing them together, or by screwing the heat shield plate 5 and the bottom member 2a. 2b and the bottom member 2a are integrated.

The bottom member 2a is formed with a control circuit housing space 7 in which the central portion is bulged upward, and the control circuit housing space 7 houses a circuit box 9 in which a control circuit board 8 is internally fixed. Circuit box 9 fixed with a stopper
The operation panel portion 9a provided integrally with the control circuit storage space 7
A part of the front surface of the bottom member 2a, and a seal film 11 forming an operation surface is attached to the front surface of the bottom member 2a, and the peripheral edge portion of the seal film 11 protruding from the operation panel portion 9a to the periphery of the bottom member 2a. Concave surface 2
By adhering to e, a flat operation surface is formed on the front surface of the bottom member 2a, and the operation panel portion 9a and the bottom member 2a are formed.
It covers and seals the boundary part of fitting with.

In the central opening 4a of the heating plate 4, a sensor holder 12 fixed to the central portion of the heat shield plate 5 is held so as to be movable up and down, and a sensor holder 14 biased upward by a spring 13 is provided. It faces the upper surface of the heating plate 4 to face it.

The temperature sensor 1 is provided on the upper end of the sensor holder 14.
5 is held, and when the container 3 is placed on the hot platen 4, the sensor holder 14 is pushed down by the spring 13 by the container 3, and the temperature sensor 15 at the upper end abuts on the container 3, The temperature can be detected by heat conduction from the container 3.

In the sensor box 12, the container 3 is placed on the heating plate 4 because of the difference in height of the sensor holder 14 when the container 3 is placed on the heating plate 4 and when it is not placed. A photo sensor 16 is provided to detect whether or not

The container 3 has a flat and fluffy body and a slightly narrowed mouth. A handle attachment member 17 made of metal is wound around the constricted portion of the mouth of the container 3, and a handle 18 made of resin is sandwiched between both ends 17a of the attachment member 17 and fastened with screws 19, thereby attaching the handle. The both ends 17a of the member 17 are drawn close to each other and fastened to the constricted part of the container 3, and the handle 18 is integrated between the both ends 17a of the handle mounting member 17 and firmly fixed to the outer surface of the container 3.

A lid 41 made of resin is put on the mouth of the container 3 so as to be removable from above. A steam port 42 is provided at a part of the rear portion of the lid 41 so that steam generated in the container 3 can escape to the outside.

The control circuit board 8 is equipped with a control circuit 22 shown in FIG. 2 using a microcomputer 21 shown in FIG. 2, and a heater drive circuit 23 shown in FIG.
Is controlled. The control circuit 22 controls the heating control means 24 utilizing the internal function of the microcomputer 21 so that the content liquid reaches a predetermined temperature based on the temperature detected by the temperature sensor 15 which detects the temperature of the container 3 which is a poor heat conductor. Control heating.

By the way, since the container 3 made of heat-resistant glass is a poor heat conductor and has a thick bottom portion in view of necessary strength and easiness of handling, when the temperature of the container 3 itself is low. There is a large difference in the heat conduction characteristics between the high and high cases. Therefore, if the heating by the heater 1 is controlled only by the temperature information from the temperature sensor 15 that abuts on the container 3 and detects the temperature of the container 3 as in the conventional case, the control according to the actual content liquid temperature cannot be performed. , A control disorder that is lower or higher than the set heating characteristics occurs, insufficient sterilization and descaling due to boiling of the content liquid due to insufficient heating, or excessive heating may cause overheating. Or

Further, the temperature sensor 15 is a glass container 3
Even if the temperature of the bottom of the container is detected, it does not correctly correspond to the temperature of the content liquid heated through the bottom of the glass container 3 whose heat conduction state is not uniform due to the difference in the temperature range as described above. The temperature-sensitive characteristic of the temperature sensor 15 is not linear with respect to the temperature rise, and the heater 1 is kept until the content liquid reaches a boiling state.
When the heating is continued by the temperature sensor 15, the temperature sensor 15 is affected by the temperature of the bottom of the glass container 3 which is heated earlier than the content liquid, and the temperature sensor 15 overshoots early and the temperature sensor 15 detects the temperature. The temperature-based heating control may not be performed correctly.

In order to solve this, in the present embodiment, the internal function of the microcomputer 21 is utilized to detect the temperature detected by the temperature sensor 15 in a predetermined temperature range T1 before boiling.
When (Fig. 3) is reached, the heating is temporarily weakened or stopped, and the temperature detected by the temperature sensor 15 is lowered to a certain temperature T2 (Fig. 3) below the predetermined temperature T1, and then the normal heating state is restored again. When the temperature detected by the temperature sensor 15 returns to the predetermined temperature T1 after the first heating adjustment unit 25 and the first heating adjustment unit 25 have worked, the temperature of the content liquid is increased from the change in the temperature detected by the temperature sensor 15. Second heating adjusting means 26 for determining the characteristics and setting subsequent heating conditions according to the determination result of the temperature rising characteristics is provided.

In the basic heating operation for controlling the heating of the content liquid to a predetermined temperature based on the temperature of the container 3 detected by the temperature sensor 15 by the operation of the heating control means 24, in this embodiment, FIG. As shown in, the content liquid has a boiling temperature of 1
After reaching 00 ° C., this boiling temperature is maintained for a predetermined time t3.

In addition, in such a basic heating control, when the temperature detected by the temperature sensor 15 reaches a predetermined temperature T1 before boiling, for example, 90 ° C. range, the first heating adjusting means 25 operates to operate the heater 1. The heating by the temperature sensor 15 is once weakened or stopped, the temperature detected by the temperature sensor 15 is lowered to a certain temperature T2 lower than the predetermined temperature T1, for example, 88 ° C., and then the normal heating state is restored again, and the container 3 of the temperature sensor 15 is returned. In addition to suppressing the overshoot of the temperature-resistance characteristic due to the temperature rise of the above by the temperature decrease during this period, while keeping the correlation with the heat conduction characteristic and the content liquid temperature with the temperature rise of the container made of a poorly heat-conductive conductor, 1 heating adjusting means 25
When the temperature detected by the temperature sensor 15 of the container 3 is returned to the predetermined temperature T1 after the operation of, the second heating adjustment means 26 operates to increase the temperature of the content liquid from the change in the temperature detected by the temperature sensor 15. Since the characteristic S1 is determined, this determination is appropriately performed in a state where the heat conduction characteristics associated with the temperature rise of the container 3, the temperature sensor temperature rise-resistance characteristics, and the content liquid temperature correlation are the same. Since the second heating adjusting means 26 sets the subsequent heating conditions in accordance with the determination result of the temperature rising characteristic S1, the heat conduction characteristics differ depending on the temperature range of the container 3 which is the poor heat conductor and the temperature of the temperature sensor 15 The content liquid can be adapted to a preset heating condition without the influence of the resistance characteristic being not stable.

For such control, the microcomputer 21 is supplied with a current obtained by converting the AC power supply 31 of the heater drive circuit 23 into a DC current by the transformer 32 and the rectifier 33, and the AC power supply 31.
The frequency synchronization signal input signal is generated by the frequency synchronization signal input circuit 34 by power supply from the microcomputer 2
It is input to 1 and used for various operation control. On the input side of the microcomputer 21, a temperature sensor 15, various operation keys 35 provided on the operation panel section 9a, various display elements 36, and an alarm for acoustically notifying various states in various operation modes. 37 and the like are connected, a triac drive circuit 38 is connected to the output side, and the energization of the heater 1 of the heater drive circuit 23 is controlled via the triac 39 to obtain a heating state required at each time. .

The second heating adjusting means 26 of this embodiment is used.
Is for setting the time t2 shown in FIG. 3 for maintaining the normal heating state by the heating control means 24, and the final adjustment to the predetermined heating state shown in FIG. Since it is started from, the predetermined heating state can be obtained without error. For example, t2 is about 4 to 5 minutes,
Although t3 is set to about 1 to 3 minutes, it is not limited to this.

FIG. 4 is a flow chart of a boiling operation program showing a specific example of such heating control, which will be described.

As shown in the figure, first, the heater 1 is turned on, and the temperature detected by the temperature sensor 15 is T1 (for example, 90 ° C.).
When it reaches, the timer t1 (for example, 40 seconds) is started and the heater 1 is turned off.

Then, it waits for the timer t1 to expire.
This is for turning off the heater 1 for 40 seconds to lower the temperature of the content liquid to a certain temperature T2 below the predetermined temperature T1. Therefore, it is the same as waiting for the temperature detected by the temperature sensor 15 to reach T2 instead of such timer control, and either may be used.

When the timer t1 expires, the heater 1 is turned on again, and after waiting for the temperature detected by the temperature sensor 15 to return to T1, the temperature rise characteristic of the content liquid is determined by the change in the temperature detected by the temperature sensor 15. Is determined, the required time t2 for the final heating control by the heating control means 24 is calculated based on the determination result of the temperature rise characteristic, the timer t2 corresponding to the set time is started, and the heater 1 is operated until the timer t2 ends. When the timer is turned on and the timer t2 ends, the heater 1 is turned off, the end of boiling is notified, and the heat retention control is performed.

In the heat retention control, the boiled liquid content is kept at a temperature of about 40 ° C., which is most suitable for infant preparation.

FIG. 5 and FIG. 6 show a second embodiment of the present invention, which is different from the first embodiment only in the heat adjustment by the second heat adjusting means 26, and the others are the same as those in the first embodiment. Same as the case. Therefore, only the points different from the first embodiment will be described, and redundant description will be omitted.

As shown in FIGS. 5 and 6, the second heating adjusting means 26 adjusts the heating state after returning to T1 after the content liquid temperature once reaches T2, but returns to the temperature T1. At this time, in the present embodiment, a predetermined boiling state of the content liquid is detected from the change of the temperature rising characteristic of the content liquid detected by the temperature sensor 15 from S1 to S2, and when this is detected, the heater 1 is turned off and the boiling state is achieved. Is notified, and the heat retention control is performed.

However, the boiling state in the present embodiment means that even if the heater 1 is turned off at this time, the boiling state of the content liquid continues for a predetermined time t3, for example, about 1 to 3 minutes, during which descaling is performed. It is in a boiling state where it will be carried out. But,
It goes without saying that the heating control for removing the descaling may be performed by controlling the heater 1 separately.

Also in the first embodiment, descaling can be performed before shifting to the heat retention control.

[0038]

According to the main features of the electric pot of the present invention, in order to heat the content liquid in the container made of a heat-defective conductor by the heater outside the container, the temperature is basically controlled by the heating control means. Based on the temperature of the container detected by the sensor, heating control is performed so that the content liquid reaches a predetermined temperature. However, in this basic heating control, when the temperature detected by the temperature sensor reaches a predetermined temperature range before boiling, the first heating adjusting means operates to weaken or stop heating once, and the temperature detected by the temperature sensor is After cooling down to a certain temperature below a predetermined temperature, it is returned to the normal heating state again to suppress the overshoot of the temperature-resistance characteristics due to the temperature rise of the container of the temperature sensor by cooling during this period, and it is composed of a heat-defective conductor. While keeping the correlation between the heat conduction characteristic and the content liquid temperature accompanying the temperature rise of the container, the temperature detected by the temperature sensor by the temperature sensor returned to the predetermined temperature after the first heating adjusting means worked. At this time, the second heating adjustment means operates to determine the temperature rising characteristic of the content liquid from the change in the temperature detected by the temperature sensor. The temperature rise-resistance characteristic of the sensor and the content liquid temperature are properly matched, and the second heating adjusting means sets the subsequent heating conditions according to the determination result of the temperature rise characteristic. , The content liquid is adapted to the preset heating state without being affected by the fact that the heat conduction characteristic differs depending on the temperature range of the container which is a poor heat conductor and the temperature-resistance characteristic of the temperature sensor is not stable. be able to.

Even if the second heating adjusting means sets the time period during which the normal heating state is maintained by the heating control means, or the temperature detected by the temperature sensor changes by a predetermined temperature rise near the boiling point. Even if the heating duration is set after that, the final adjustment to the predetermined heating state is started from the proper heating state detection state, so the predetermined heating state can be obtained without error. To be

[Brief description of drawings]

FIG. 1 is a sectional view showing an electric pot as a first embodiment of the present invention.

FIG. 2 is a block diagram of a control circuit of the electric pot of FIG.

FIG. 3 is a graph showing a temperature change state of the content liquid corresponding to the heating control state of the electric pot of FIG.

FIG. 4 is a flowchart showing a boiling program for the electric pot of FIG.

FIG. 5 is a graph showing the temperature change of the content liquid corresponding to the heating control state showing the second embodiment of the present invention.

FIG. 6 is a flowchart showing a boiling program for the electric pot of FIG.

[Explanation of symbols]

 1 Heater 2 Base 3 Container 15 Temperature Sensor 22 Control Circuit 23 Heater Drive Circuit 24 Heating Control Means 25 First Heating Adjusting Means 26 Second Heating Adjusting Means T1 Predetermined Temperature T2 Certain Temperature S1 Temperature Rising Characteristics

Claims (3)

[Claims] 1. An electric pot for heating a content liquid in a container made of a poorly heat-conductive conductor by a heater outside the container, the temperature sensor detecting the temperature of the container, and the content liquid based on the temperature detected by the temperature sensor. When the temperature detected by the temperature sensor reaches a predetermined temperature range before boiling, the heating is temporarily weakened or stopped, and the temperature detected by the temperature sensor is the predetermined temperature. A first heating adjusting means for returning to a normal heating state after lowering to a certain temperature below the temperature, and a temperature when the temperature detected by the temperature sensor returns to the predetermined temperature after the first heating adjusting means operates. It is characterized by further comprising: second heating adjusting means for judging the temperature rising characteristic of the content liquid from the change in the temperature detected by the sensor, and setting the subsequent heating conditions according to the judgment result of the temperature rising characteristic. An electric kettle. 2. The electric pot according to claim 1, wherein the second heating adjusting means sets a time period during which the heating control means maintains the normal heating state. 3. The second heating adjusting means sets the subsequent heating duration when the change in temperature detected by the temperature sensor has a predetermined temperature rising characteristic near the boiling point of the content liquid. The electric pot according to claim 1.