JPH0440591Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) The present invention relates to an electric pot, in particular, a steam temperature sensor that detects steam temperature, a liquid temperature sensor that detects liquid temperature, and a temperature sensor that detects the temperature detected by both sensors. The present invention relates to an electric pot equipped with a control device comprising control means for controlling a heater drive circuit to perform a boiling operation and a warming operation.

(Prior Art) In recent years, an electric pot with a built-in microcomputer that controls everything from boiling water to keeping warm has been proposed and put into practical use, for example, in Japanese Patent Application No. 16407/1983. ing. The electric pot described in the same specification basically includes a steam temperature sensor that detects the steam temperature, a liquid temperature sensor that detects the liquid temperature, and a heater that detects the boiling temperature when the temperature detected by the steam temperature sensor reaches the boiling reference temperature. A control device includes a comparison means for outputting a signal to stop the drive circuit, and a control means for controlling the heater drive circuit to perform a boiling operation and a heat-retaining operation according to the detected temperature detected by both of the sensors. .

In this electric kettle, the boiling operation is normally performed after cold water is placed in a container and then heated by a water heater and an insulating heater to start the boiling operation, and the temperature detected by the water temperature sensor that detects the liquid temperature is This is done by stopping the power supply to the heat retention heater when the heat retention reference temperature is reached, and stopping the power supply to the water boiling heater when the temperature detected by the steam temperature sensor that detects the steam temperature reaches the boiling reference temperature. On the other hand, if the boiling operation is performed with the lid open or if the steam temperature sensor is abnormal, even if the water boils, the temperature detected by the steam temperature sensor will never reach the boiling reference temperature. A timer is provided to forcibly stop the energization to both heaters if boiling is not completed even after a certain period of time has elapsed after the start of the boiling operation, that is, after the start of energization to both heaters.

(Problem to be solved by the invention) However, since the timer is originally set for the time required to boil water at an extremely low temperature (usually room temperature), if the water temperature is high, for example, When boiling or re-boiling water by adding water, even though it boils in a short time, the time from starting the boiling operation to stopping power to the heater is too long in the event of an abnormality, resulting in high power consumption. Not only would the amount increase, but there was also the risk of hot water scattering when the lid was opened and dry heating caused by water evaporation.

(Means for solving the problem) As a means for solving the problem, the present invention, as shown in FIG. The liquid temperature sensor 5 and the heater drive circuit 3 are controlled according to the temperature detected by the liquid temperature sensor 5 to perform boiling operation and heat retention operation, and when boiling is detected by the temperature detected by the vapor temperature sensor 4, the boiling is performed. In an electric pot equipped with a control device consisting of control means 10 for switching from operation to heat retention operation, the temperature detected by the liquid temperature sensor 5 is compared with a preset reference temperature, and when the detected temperature reaches the reference temperature, a signal is generated. and a safety timer 9 which is activated by a signal from the comparison means 8 and outputs a signal after a predetermined time has elapsed. When boiling is not detected based on the detected temperature, the heater drive circuit 3 is forcibly stopped by a signal from the safety timer 9.

This second safety timer 9 operates independently or simultaneously with the start of the boiling operation for a predetermined period of time (hereinafter referred to as
After the first set time) has elapsed, the heater drive circuit 3
It may also be provided together with a timer 11 (hereinafter referred to as the first safety timer) that stops the safety timer.

(Function) When a conventional electric pot starts a boiling operation, electricity is started to be supplied to the water boiling heater 2a and the warming heater 2b, and the cold water is heated. When the water temperature detected by the liquid temperature sensor 5 during the boiling operation reaches the reference temperature (for example, 85° C. which is the heat retention reference temperature), the control means 10 receives a signal from the comparison means 8.
energization to the heat-retaining heater 2b is stopped, but the water heater 2a is kept energized until the water boils.

In normal operation, when the water boils, the temperature detected by the steam temperature sensor 4 reaches the boiling reference temperature, and in response to that signal, the power to the water heater 2a is stopped and the water is kept warm, but the water does not boil. If there is an abnormality such as the lid remaining open, the boiling operation will not be completed because the temperature detected by the steam temperature sensor 4 will not reach the boiling reference temperature no matter how long it takes. In the electric pot according to the present invention,
The first set time (for example, 50 minutes) is set by the first safety timer after starting the boiling operation, or the first set time is set by the safety timer 9 after the temperature detected by the liquid temperature sensor 5 reaches the reference temperature. If the temperature detected by the steam temperature sensor 4 reaches the boiling reference temperature before the set time (for example, 10 minutes) has elapsed, the power supply to the water heater 2a is stopped and the water heater 2a enters the warming operation, but the set time does not elapse. If the temperature detected by the steam temperature sensor 4 does not reach the boiling reference temperature, the first safety timer 11 or the second safety timer 9 times up, and in response to that signal, the control means 10 stops the heater drive circuits 3a and 3b. Then, the power supply to the water boiling heater 2a and the warming heater 2b is stopped.

Also, if the re-boiling switch SW1 is pressed while keeping warm, the boiling operation will start, but in this case as well,
In the same manner as in the previous case, the first safety timer 11
Then, the safety timer 9 starts operating in sequence. In this case, since the initial temperature of the water is high, the time from the start of the boiling operation until it reaches boiling is short, and the heating time in the event of an abnormality is limited by the set time of the safety timer 9, but normal operation In this case, the temperature detected by the steam temperature sensor 4 reaches the boiling standard temperature before the set time and the boiling operation shifts to the keep-warm operation, or if the lid is open or an abnormality occurs in the steam temperature sensor 4. In this case, after the time set by the safety timer 9 has elapsed, the control means 10 receives a signal from the safety timer 9 and starts the heater drive circuit 3.
The operations of a and 3b are stopped, and power supply to the heater is stopped.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 shows a control device for an electric pot according to the present invention, which includes a drive circuit 3a for driving a water heater 2a, a drive circuit 3b for driving a heat-retaining heater 2b, and a steam temperature control device for detecting steam temperature. A sensor 4, a liquid temperature sensor 5 that detects the liquid temperature, and a water level detection electrode 6 that detects the water level in the container.
, reboiling switch SW1, and timer switch
It is composed of a SW 2, an alarm buzzer 12, and a microcomputer 10 equipped with light emitting diodes _LED1 to _LED5 for displaying operating conditions.

The microcomputer 10 is composed of a central processing unit (CPU), a memory (ROM, RAM), a timer, and an input/output port (I/O port).
A safety timer 11 and a safety timer 9 are configured. The memory also stores a water injection reference temperature T ₁ , a heat retention reference temperature T ₂ , an empty firing reference temperature T ₃ , a boiling steam temperature T ₄ , and various timer setting times.

In addition, in the figure, 13 is a relay, 14 is a photo try-out coupler, 15 is a try-out, Q ₁ ,
Q ₂ is a transistor and R is a resistor.

Below, the operation of the electric pot with the above configuration is shown in Figures 3 to 3.
This will be explained according to the flowchart shown in FIG.

When it is determined that the water level is present in the power-on mode (step 1) and the second detection temperature t ₂ detected by the liquid temperature sensor 5 is determined to be below the water injection reference temperature (T ₁ , for example, 79°C). (Step 2), enter boiling mode. If it is determined in step 1 that the water level is insufficient, the system will shift to water supply notification mode, and if it is determined in step 2 that the water level is equal to or higher than the water injection reference temperature (T ₁ ), it will shift to heat retention mode. .

When entering boiling mode, first, water boiler heater 2 is turned on.
a and the heat retention heater 2b are turned off (step 3), and the boiling mode display light emitting diode LED _{1 is} turned off.
lights up (step 4) and issues a warning with the buzzer 12 (step 5). Next, the short-time timer starts counting (step 6), and during a short period of time (for example, 3 seconds), it is determined whether or not the steam temperature sensor 4 and liquid temperature sensor 5 are disconnected, and the second detected temperature _t2 is determined to be the dry-burning standard. It is determined whether the temperature is above (T ₃ , e.g. 107°C) and whether the timer switch SW ₂ is on or not (steps 7 to 10). If each condition is not met, the abnormality notification mode, Shifts to empty firing notification mode and timer mode.

When each condition is satisfied and the process moves to step 11, and it is determined that the detected temperature t ₁ detected by the steam temperature sensor 4 is below the boiling reference temperature (T ₄ ), the first safety timer 11 is activated for the first set time ( For example, 50
(step 12), the water heater 2a and the heat-retaining heater 2b are energized (step 13), and water boiling is started. After energization starts, the steam temperature sensor 4 and liquid temperature sensor 5 are checked for disconnection (step 14), whether the first set time has elapsed (step 15), and the second detected temperature t ₂ is determined to be the dry-firing reference temperature (T _{3 )} . ) or more (step 16),
Determining whether the water level is present (step 17), determining whether timer switch SW2 is on or not (step 18),
It is determined whether the first detected temperature t ₁ is equal to or higher than the boiling reference temperature (T ₄ ) (step 19), and the second detected temperature t ₂ is determined to be higher than the boiling reference temperature (T 4 ).
The heat retention reference temperature (T ₂ , e.g.
Repeat steps 14 to 20 until the temperature reaches 85℃. If it is determined in step 19 that the temperature detected by the steam temperature sensor 4 is equal to or higher than the boiling reference temperature (T ₄ ), the mode is set to keep-warm mode or dry-heat notification mode depending on the temperature detected by the liquid temperature sensor 5. Migrate (step 100).

In the process of repeating the above steps, when it is determined that the first set time (50 minutes) has elapsed, the mode shifts to the abnormality alarm mode, and after stopping electricity to both heaters (step 101), the light emitting diode LED ₂ is turned off. is turned on (step 102), and the buzzer 12 continues to notify abnormalities. Also, if it is determined that there is a disconnection in the steam temperature sensor 4 and liquid temperature sensor 5 (step
In step 14), as in the case described above, the system shifts to the abnormality notification mode and uses the buzzer 12 to notify the abnormality.

When the second detected temperature t ₂ reaches the heat retention reference temperature (T ₂ ) within the first set time, the process continues from step 20.
21, the safety timer 9 that sets a relatively short time (for example, 10 minutes) starts counting, and keeps the water heater 2a on and turns off the warming heater 2b (step 22). To prevent problems such as splashing of hot water due to abnormal boiling by heating only with a water heater 2a. This state is maintained until the first detected temperature _t1 reaches the boiling reference temperature, but during this time the step
In addition to making the same judgments as those made from step 14 to step 18 (steps 23, 24, 26, 27, 28, etc.), it is also judged whether or not the second set time has elapsed (step 25).

If it is determined in step 25 that the second set time has passed before the first detected temperature t ₁ reaches the boiling reference temperature (T ₄ ), the system shifts to the abnormality notification mode and stops energizing both heaters. (Step 101), the light emitting diode LED ₂ is turned on (Step 102), and the buzzer 12 continues to notify the abnormality.

In the process of repeating the flow from step 22 to step 30, when the first detected temperature t ₁ reaches the boiling reference temperature (T ₄ ) before the first set time and the second set time have elapsed, the mode shifts to the heat retention mode. Note that if cold water is added and the water temperature drops, the step
At step 29, it is determined that the second detected temperature t ₂ is less than the heat retention reference temperature (T ₃ ), and the process moves to step 13, where both heaters are used to heat again.

In the keep-warm mode (steps 31 to 46), first, the water heater 2a is turned off to turn off both heaters (step 31), and the light-emitting diode LED ₂ is turned on to indicate that the water is being kept warm (step 32). . Next, it is determined whether or not the boiling mode has shifted to the warming mode (step 33), and if so, the buzzer 12 notifies that boiling has been completed (step 34), and the process moves to step 35, where the boiling mode is started. If it is not in the mode, the process moves to step 35 without sounding the buzzer 12.

In this step 35, the third safety timer starts counting, but this third safety timer does not shift to the keep warm mode and then to other modes, and only the keep warm mode lasts for a predetermined period of time, for example, 24 hours. (Step 38)
The mode shifts to the dry firing mode, where the control means 10 receiving the signal from the third safety timer stops the heater drive circuits 3a and 3b.

Even during the heat retention mode, it is determined whether or not the steam temperature sensor 4 and the liquid temperature sensor 5 are disconnected (step 36).
The second detected temperature t ₂ is the dry firing reference temperature (for example, 107
) (step 37), whether the water level is present or not (step 39), and whether the timer switch SW is turned on (step 41)
In addition to determining whether the second detected temperature _t2 is below the water injection reference temperature (step 40), and determining whether the first detected temperature _t1 is above the boiling reference temperature (step 40),
42), it is determined whether the reboiling switch SW1 is turned on (step 43) and whether or not the second detected temperature _t2 is equal to or higher than the heat retention reference temperature ( _T2 ) (step 44).

If it is determined in step 44 that the second detected temperature _t2 is equal to or higher than the heat retention reference temperature, the flow from step 36 to step 45 is repeated while keeping both heaters in the off state, and the second detected temperature _t2 is kept warm. When the temperature becomes lower than the reference temperature (T ₂ ), the water heater 2a is turned off and only the heat retention heater 2b is turned on (step 46), and the flow from step 36 to step 46 is continued until the temperature reaches the heat retention reference temperature (T ₂ ) or higher. repeat.

When cold water is added during the heat retention operation and the temperature of the hot water falls below the water injection reference temperature, the mode shifts to the boiling mode from step 40, and the flow from step 3 is repeated. In this case as well, the first safety timer 11 starts counting, and then, when the second detected temperature reaches the heat retention reference temperature (T ₂ ), the safety timer 9 starts counting, just as when changing to the boiling mode after pouring cold water. The safety timer 9 starts counting, but because the initial water temperature shifts to boiling mode when it is relatively high, the safety timer 9 starts operating after the second detected temperature t ₂ reaches the heat retention reference temperature (T ₂ ). Since the time-up occurs first, even if the heaters are operated with the lid open, the power supply to both heaters will be stopped in a short time.

(Effect of the invention) As is clear from the above explanation, in the electric pot according to the invention, after the liquid temperature reaches the heat retention temperature, specifically, the detected temperature detected by the liquid temperature sensor reaches the heat retention reference temperature. We have installed a safety timer that outputs a signal to stop power to the heater after a predetermined period of time has passed. Even if an abnormality occurs, such as a disconnection of the water line or boiling water with the lid open, boiling will not continue unnecessarily, resulting in superior effects such as improved safety and the prevention of unnecessary power consumption. Moreover, when the second safety timer is installed together with the first safety timer, it can be set to a shorter time regardless of the first safety timer.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electric pot according to the present invention, FIG. 2 is a circuit diagram of its control device, and FIGS. 3 to 5 are flowcharts of its operation. 1... Container, 2... Heater, 2a... Water boiler heater, 2b... Heat retention heater, 3, 3a, 3b...
...Heater drive circuit, 4...Steam temperature sensor, 5
...Liquid temperature sensor, 6...Water level detection electrode, 7...
Reference temperature setting means, 8... Comparison means, 9... Safety timer (second safety timer), 10... Control means, 10, 11... First safety timer.

Claims (1)

[Scope of utility model registration request] A steam temperature sensor that detects steam temperature, a liquid temperature sensor that detects liquid temperature, and a heater drive circuit that controls a heater drive circuit to perform a boiling operation and a heat-retaining operation according to the temperature detected by the liquid temperature sensor, and the vapor temperature sensor In an electric pot, the temperature detected by the liquid temperature sensor is compared with a preset reference temperature in an electric pot equipped with a control device comprising a control means for shifting from a boiling operation to a warming operation when boiling is detected by the temperature detected by the liquid temperature sensor. A comparison means that outputs a signal when the detected temperature reaches a reference temperature, and a safety timer that is activated by the signal from the comparison means and outputs the signal after a predetermined period of time have elapsed, and a predetermined period of time set by the safety timer is provided. When boiling is not detected by the temperature detected by the steam temperature sensor before the boiling point has elapsed,
An electric pot characterized in that a heater drive circuit is forcibly stopped by a signal from the safety timer.