JPH0351270B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a boiling control device for an electric stove that detects the temperature at the bottom of the cooker and controls the amount of electricity supplied to a sheathed heater, particularly for controlling the size of the cooker or boiling temperature. This invention relates to controlling the amount of electricity applied to a sheathed heater efficiently regardless of the amount of hot water.

[Prior Art] Fig. 6 is a plan view of a conventional electric stove. In the figure, 1 is a sheathed heater, 2 is a temperature sensor that detects the temperature at the bottom of the cooker placed on the electric stove, and 3 is a sheathed heater. An automatic water boiling setting switch adjusts the amount of heat generated by the heater 1, and 4 is a power switch.

In such an electric stove, energization of the sheathed heater 1 is started by inputting the power switch 4, and water is heated with the amount of heat set by the automatic water boiling setting switch 3. At this time, temperature sensor 2
The temperature at the bottom of the cooker is constantly detected, and the energization of the sheathed heater 1 is controlled so as to output a set amount of heat based on the temperature detection signal from the temperature sensor 2. Water filled in a cooking device such as a cooking device, a kettle, or a pot is heated and controlled by a sheathed heater 1 whose electricity is controlled until it boils.

[Problems to be solved by the invention] By the way, in the boiling control of conventional electric stoves,
After a temperature sensor detects boiling, the power applied to the sheathed heater is reduced, but this has the problem of overboiling due to residual heat from the sheathed heater. Therefore, the cooker itself would heat up more than necessary, causing hot water to spill over, creating a danger and making it impossible to leave the electric stove for long periods of time.

With conventional electric stoves like this, it was unimaginable to automatically boil water after a predetermined time, but it would be convenient if water could be automatically boiled at a predetermined time when you want to start cooking, and you could start cooking right away. This allows you to save wasted time on cooking.

This invention was made in order to solve this problem, and it is possible to automatically boil water after a set time and to perform stable boiling control even when the size of the cooker and the amount of water are different. The purpose is to obtain a boiling control device for electric stoves that can be used.

[Means for solving the problem] The boiling control device for an electric stove according to the present invention includes:
A timer time setting means for starting energization of the sheathed heater at the timer time set by the reservation timer setting switch, and a timer time setting means for starting energization of the sheathed heater at the timer time set by the reservation timer setting switch, and a timer time setting means for detecting the gradient of temperature rise of water between predetermined temperatures and determining the duration of maximum power energization. The maximum power energization means calculates and energizes the maximum power until the end of the duration time, and compares the detected temperature of the bottom of the cooking device with a predetermined temperature, and determines whether the detected temperature is at a higher level than the predetermined temperature. temperature determining means for making a determination; and the temperature determining means determines a slope of temperature rise as a selection point of the control method when the detected temperature is at a lower level than the predetermined temperature and at the end of maximum power application. If the detected temperature is smaller than the predetermined temperature, the first partial energization means performs partial energization until the temperature increase gradient reaches a boiling gradient that is considered to be a boiling state, and the temperature determination means determines that the detected temperature is lower than the predetermined temperature. When the temperature is at a low level and the gradient of temperature rise is greater than the selection gradient after the maximum power is applied,
A second partial energization means performs partial energization for a predetermined adjustment time to reach a boiling state, and the temperature determination means determines that when the detected temperature after the start of energization to the sheathed heater is at a higher level than the predetermined temperature; ,2
The gradient of temperature rise between predetermined temperatures is detected at the location, and the maximum power is applied until the ratio of the two gradients reaches a predetermined ratio that does not exceed the boiling point, and after reaching the predetermined ratio, the boiling state is reached. It is characterized by comprising a third partial energization means that performs partial energization for a predetermined adjustment time.

[Operation] According to the above configuration, energization of the sheathed heater is started after a preset timer time. Then, before the boiling point, the power supplied to the sheathed heater is reduced, and if the temperature rise is small, partial energization control is performed until the temperature rise becomes so gentle that it is considered that the boiling point has been reached. be exposed. In addition, when the temperature rise gradient is large, partial energization is controlled for a relatively short adjustment time to prevent overheating, and regardless of the size of the cooker or the amount of water, the bottom of the cooker is heated to the sheathed heater at almost the boiling point. The power supply is stopped.

According to such boiling control, boiling water is obtained after a set time, and the boiling state is maintained in a stable state without overheating the cooker.

[Example] Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a plan view of an electric stove of the embodiment.
4 is the same as the conventional device.

In the figure, 5 is a heat-sensitive element in the temperature sensor 2;
Reference numeral 6 denotes a microcomputer, which includes timer time setting means, maximum power energization means, first partial energization means, second partial energization means, and third partial energization means, which are characteristic components of the present invention. It is. Then, the detection signal of the temperature sensor 2 and the output signal of the automatic water boiling setting switch 3 are input. 7 is a transistor, and 8 is a photocoupler. By turning on and off the transistor 7 based on a control signal outputted from the microcomputer 6, the photocoupler 8 is activated and the energization of the sheathed heater 1 is controlled. 9 is DC power supply, 10
is a thyristor that performs rectification, 11 is a commercial power supply,
12 is a buzzer that informs you that the water has boiled, 5
0 is a reservation timer setting switch for setting the timer time, and is provided on the operation panel of the electric stove shown in FIG.

The embodiment has the above-mentioned configuration, and its operation will be explained based on the flowchart of FIG.
In addition, Figures 4 and 5 are graphs showing the state of water temperature when boiling control is performed. Figure 4 is for A route control in Figure 3, and Figure 5 is for B route control in Figure 3. In this case, FIG. 7 shows the case of C route control in FIG.

In FIG. 3, first, in step 51, it is determined whether or not the reservation timer is set by the reservation timer setting switch 50. If the reservation timer is not set, the process moves to step (13) and the reservation timer is set. If so, proceed to step (52).
Then, in step (52), it is determined whether or not the timer time has elapsed, and when the timer time has elapsed, the power switch 4 and automatic water boiling setting switch 3 are turned on, and the process moves to step (13). Temperature detection is performed.

Next, in step (14), increase the heating power to maximum.
In other words, the maximum power is applied, and in step (15), when the power switch 4 is turned on, the temperature is detected in step (13), and when the automatic water boiling setting switch 3 is turned on, the temperature is detected in step (14).
The heating power is maximized at , that is, the maximum power is applied.

Next, in step (15), H seconds have passed (for example, 30 seconds) after the automatic water boiling setting switch 3 has been input.
, and the process proceeds to step (16) to determine whether or not the detected temperature T ₁ is greater than a predetermined temperature T ₂ (which is a branch temperature to be described later). In the embodiment, this predetermined temperature T ₂ is approximately 45
℃, and if T ₁ ≧T ₂ , the process moves to step (37), and if T ₁ <T ₂ , the process moves to step (17).

In step (17), the gradient of the water temperature rise between predetermined temperatures is detected to calculate the maximum power supply duration _H2 , and as shown in _FIG . °C) to _T4 (e.g. 77.0
First, find the time H ₁ required to reach ℃). and,
This required time _H1 is a value indicating the gradient of temperature rise, and based on this temperature rise gradient, the sheath heater 1
Calculate the maximum power continuation time H ₂ before reaching the boiling temperature of 100°C, taking into account residual heat, etc.
Then, based on this duration _H2 , the maximum power is continued to be energized.

Next, in step (18) shown in FIG. 3, it is determined whether the gradient of the temperature rise is larger than the selection gradient determined as the selection point of the control method, and the required time H indicating the gradient of the temperature rise is determined. It is determined whether ₁ is greater than a predetermined time _H3 indicating the selection gradient. In other words, if the temperature increase gradient is smaller than the selected gradient (H ₃ <H ₁ YES), the control method (A route) using the first partial energization means is performed, and if it is larger (H ₃ > H ₁ , that is, H ₃ < For H ₁ judgment (NO), control method using second partial energization means (B route)
will be carried out.

Therefore, if H ₃ < H ₁ , the process moves to step (19) where A route control is performed, and if H ₃ ≧ H ₁ , B
Proceed to step (29) for route control. In this step (19), the heating time from the temperature _T4 is measured, and it is determined in step (20) whether or not the heating time _H4 has elapsed for the duration _H2 . That is, in step (20), it is determined whether the heating time _H4 is longer than the duration time _H2 , and if _H2 > _H4 , the process returns to step (19) and it is determined that _H2 ≦ _H4 . If so, proceed to step (21) and perform partial energization to reduce the heating power to A%, for example 70%.

In route A control, since the temperature increase gradient is originally small, it takes time to reach the boiling temperature, so the temperature increase gradient is further detected and partial energization is performed until the boiling gradient is reached, which can be regarded as the boiling temperature. That is, in step (23), the temperature of the cooking bottom is further detected, and then, in step (24), the time _H6 after partial energization is measured.

In step (25), the time after this partial energization is
It is determined whether or not H ₆ is greater than a predetermined time value H _7. If H ₆ < H ₇ , the process returns to step (24), and if H ₆ ≧ H ₇ , the process proceeds to step (26). At that time, temperature T ₆ is detected.

Then, in step (27), it is determined whether the difference between the two detected temperatures, that is, T ₆ - _{T 5} is greater than the temperature T ₇ representing the boiling gradient. and,
If T ₆ −T ₅ ≦T ₇ , the temperature at the bottom of the cooker has reached a temperature corresponding to the boiling temperature, and the buzzer sounds in step (28). On the other hand, if T ₆ −T ₅ > T ₇ ,
Proceeding to step (33), the temperature increase gradient is further detected.

In steps (33) to (36), the boiling gradient detection function described above is performed, and the difference between the newly detected detected temperature _T8 and the detected temperature _T6 is the temperature _T7 indicating the boiling gradient.
If it is smaller, it moves to step 28 and sounds the buzzer. If this temperature difference T ₈ -T ₆ is larger than the temperature T ₇ , the process returns to step (26) and the temperature increase gradient is further detected. This operation is repeated as many times as the temperature rise gradient reaches a boiling gradient, and only when the boiling gradient is reached is a buzzer alerting the user that the water has boiled. Note that after the buzzer notifies the temperature, the current is continued at a small amount of power to maintain the temperature at 100°C, which is 400W in the example.

Next, the second partial energization means (B route control) after maximum power energization will be explained.

In step (18), the temperature rise gradient is divided into cases where it is low and high, but when the temperature rise gradient is larger than a predetermined value, that is, when H ₃ ≧ H ₁ , the process moves to step (29). The maximum power is continued for the duration _H2 determined in step (17).

Then, after the duration _H2 has elapsed, partial energization is performed in step (30) to reduce the heating power to A%, which in the example is 70%. In the case of this B route control,
Since this is a case where the temperature increase gradient is large, the time required to reach the boiling temperature is extremely short and the time can be easily estimated, so a buzzer indicating the end of boiling is sounded after the adjustment time _H7 . Therefore, in step (31), the time _H9 from the start of partial energization is measured, and in step (32) it is determined whether or not this time _H9 has reached the adjustment time _H7 . H After ₇ hours, the buzzer will sound after 30 seconds in the example.

As shown in Figure 5, when the gradient of temperature rise is large, the time to reach boiling temperature is extremely quick, and by ending the partial energization for temperature rise before the boiling point, it is possible to overheat the cooker. It is possible to prevent heating and maintain a good boiling state of hot water.

Next, the third partial energization means (C route control) will be explained with reference to FIG.

In this embodiment, C route control is performed when the starting temperature for boiling water is high, and this C route control draws a temperature rise curve as shown in Figure 7, and the temperature of the water reaches a boiling point. Since the time required to reach the maximum power is short, the heating time at the maximum power is not calculated, and the heating time is controlled by the slope ratio.

In the step (16), it is determined whether the detected temperature T ₁ is higher than the predetermined temperature T ₂ (45°C), and when T ₁ ≧T ₂ , the process moves to step (37) and the temperature T 1 is determined. Measure the required time H ₁₀ from ₉ to T ₁₀ . Then, in step (38), the time _H11 required for the temperature to rise by a predetermined temperature _T11 from temperature _T10 is measured, and in step (39), _aH10 and _H11 are compared.

That is, in step (39), the slope ratio a is multiplied by the time _H10 , and it is determined whether the value of this _aH10 is greater than the time _{H11.If aH10} ≦ _H11 , the step (30) and heating power to 70
Perform partial energization to %. After that, as described above, partial energization is performed for the adjustment time _H7 , and then the buzzer is sounded.

If aH ₁₀ >H ₁₁ , the process moves to step (40) and temperature detection is performed once again in the same manner as described above. Then, for example, from the detected temperature _T12 to a predetermined temperature
The time _H12 required for the temperature to rise by _T11 is measured in step (41).

Next, in step (42), it is determined whether aH ₁₂ is greater than H ₁₁ in the same way as in step (39), and if aH ₁₁ ≦H ₁₂ , the process moves to step (30) and the partial processing is performed. Turn on electricity. Also aH ₁₁ >
If H ₁₂ , the process returns to step (40) and temperature detection is performed again.

In this way, the C route control is such that when the water temperature is high when the electric stove is input, electricity is applied at maximum power until the predetermined temperature increase gradient reaches a predetermined ratio, and after reaching the predetermined ratio, the boiling point is reached. Partial energization is performed only during the adjustment time.

[Effects of the Invention] As explained above, the present invention calculates the duration of maximum power application from the gradient of temperature rise, applies the maximum power during this duration, and after this is finished, the maximum power is applied depending on the magnitude of the gradient of temperature rise. In addition to boiling control that performs different types of partial energization, we also perform timer control that energizes the sheathed heater at a timer time, so water can be boiled automatically after the preset timer time. Since the temperature of this hot water is in an extremely stable boiling state, it is possible to obtain hot water in a satisfactory manner without monitoring the hot water inside the cooking device.

Therefore, it is possible to obtain a convenient electric stove with a reservation timer that can be used with confidence.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the boiling control device according to the present invention, FIG. 2 is a plan view of the electric stove of the present embodiment, and FIG. 3 is a flowchart showing the operation of the control device of the present invention. Figure 4 is a graph showing the rise in water temperature due to route A control, Figure 5 is a graph showing the rise in water temperature due to route B control, and Figure 6 is a graph showing the rise in water temperature due to route B control.
The figure is a plan view of a conventional electric stove, and FIG. 7 is a graph showing the temperature rise of water by C route control. In the figure, 1 is a sheathed heater, 2 is a temperature sensor, 3 is an automatic water boiling setting switch, 4 is a power switch, and 6 is a microcontroller including a timer time setting means, maximum power supply means, and first and second partial power supply means. The computer 50 is a reservation timer setting switch. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a boiling control device for an electric stove that detects the bottom temperature of the cooker and controls the amount of electricity applied to the sheathed heater in order to boil water, a timer time setting means for starting energization of the sheathed heater at a time of 100 seconds; a temperature determination means for comparing the detected temperature at the bottom of the cooker with a predetermined temperature and determining whether or not the detected temperature is at a higher level than the predetermined temperature; By the means, when the detected temperature is at a lower level than the predetermined temperature and the gradient of temperature rise at the end of maximum power application is smaller than the selected gradient determined as the selection point of the control method, the gradient of temperature rise is determined by the means. first partial energization means for partially energizing until the temperature reaches a boiling gradient that is considered to be in a boiling state; Later, when the gradient of temperature rise is larger than the selected gradient, the second partial energization means performs partial energization for a predetermined adjustment time to reach a boiling state, and the temperature determination means starts energizing the sheathed heater. When the subsequent detected temperature is at a higher level than the predetermined temperature, the gradient of temperature rise between the predetermined temperatures is detected at two locations, and the temperature is increased to the maximum until the ratio of the two gradients reaches a predetermined ratio that does not exceed the boiling point. A boiling control device for an electric stove, comprising: third partial energization means that energizes power and, after reaching the predetermined ratio, partially energizes for a predetermined adjustment time to reach a boiling state.