JPH04266722A - Boiling control device - Google Patents

Abstract

PURPOSE:To provide a boiling control device which can check continuous wasteful boiling, use electric power effectively and enables a user to always use hot water boiled to the very limit. CONSTITUTION:Expansion of a piezoelectric vibrating plate 1 caused by steam at the start of boiling is quickly detected by an expansion detecting portion 3 and a main control portion 10 stops the application of an electric current to a heater 21 for boiling water. At the time of warming, the expansion of the piezoelectric vibrating plate 1 caused by the steam at the start of boiling is quickly detected by the expansion detecting portion 3, and the main control portion 10 stops the application of an electric current to a heater 23 for warming, and when the steam stops, the contraction of the piezoelectric vibrating plate 1 is detected quickly by a contraction detecting portion 6, and the main control portion 10 starts the application of an electric current to the heater 23. Thus, when the water is boiled, the steam hardly leaks out so that there is no possibility that the materials in the periphery thereof are damaged by moisture. Furthermore, as boiling is not continued wastefully, electric power can be used effectively, and when water is once boiled, the boiled water is quickly turned into the warm condition so that hot water boiled to the very limit can be used.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling control device for electric jar pots, etc., which is effective in quickly detecting boiling and maintaining heat at a high temperature just above the boiling point.

0002

2. Description of the Related Art In recent years, a boiling detection method has become mainstream, in which temperature rise is detected using a thermistor and boiling is determined when the temperature rise gradient becomes almost zero. For heat retention, the temperature is similarly detected using a thermistor, and a temperature sufficiently lower than the boiling point is set as a threshold value to control the energization of the heat retention heater.

Conventionally, boiling control devices for electric jar pots and the like of this type generally have a circuit configuration as shown in FIG. A control unit 1 consisting of a microcomputer outputs a control signal to an energization control unit 2, and outputs a control signal to a contact point of a relay 4 connected in series to a first heater 3 for boiling water, or a first heater 3 for keeping water warm after boiling. The circuit of the AC power source 7 is opened and closed by turning on and off the contacts of a relay 6 connected in series to the second heater 5. The thermistor 8 is attached to a part that can detect the water temperature in the tank, and outputs a resistance value corresponding to this water temperature to the AD converter 9. The AD converter 9 converts this resistance value into a digital signal and inputs it to the control section 1. Upon receiving this information, the control unit 1 recognizes the current water temperature in the tank using an internal calculation function, determines whether subsequent control is for keeping warm or boiling, and controls the energization control unit 2. Further, the operation section 10 is operated by the user to input an instruction to the control section 1 when the user wants to boil the water that is being kept warm again.

When the electric jar pot with the above configuration is operated, the control section 1 starts a boiling operation and issues a control signal to the energization control section 2 to energize the first heater 3. That is, the energization control section 2 closes the contacts of the relay 4 and heating is started. This situation is shown in FIG. first heater 3
When the water is energized, the water temperature rises, but the temperature rise stops when it reaches the boiling point. The control unit 1 constantly monitors the water temperature picked up by the thermistor 8, assumes that the water has boiled when the temperature no longer increases, and controls the energization control unit 2 to turn on the first heater 3.
Switch the control signal to stop energizing. This opens the contacts of the relay 4, and the supply of electricity to the first heater 3 is stopped. After this, the control section 1 shifts to a heat-retaining operation. That is, the data of the AD converter 9 is continuously monitored, and the water temperature is T[
℃], a control signal is output to the energization control section 2 so as to energize the second heater 5. The energization control unit 2 closes the contacts of the relay 6 and starts energizing the second heater 5 . Further, when the water temperature rises above T [°C], the energization control unit 2 stops the energization to the second heater 5.
Outputs a control signal to. In this case, the energization control unit 2 opens the contacts of the relay 6 to stop energizing the second heater 5 . As shown in FIG. 4, the water temperature during this heat-retaining operation changes upward and downward around the heat-retaining temperature T [° C.]. This heat retention temperature T [° C.] is set lower than the boiling point. The reason for this is that if the heat retention temperature is higher than the boiling point, the above-mentioned heat retention control cannot be performed and the product will always boil. Furthermore, when the atmospheric pressure is low, the boiling point also decreases, so the heat retention temperature T [° C.] is not set to a very high temperature. Therefore, when the user needs hot water, he/she can use the control unit 10 using the operation unit 10.
It was necessary to switch to boiling operation again.

[0005]

[Problems to be Solved by the Invention] Conventional boiling control devices for electric jar pots and the like monitor the rise in water temperature and detect boiling when the temperature rise stops, as described above. In this case, the temperature rises at a slow rate during heating, and as a practical matter, it is difficult to determine in a short period of time whether the temperature is rising or stable. For this reason, a certain amount of time is required to reliably detect that the temperature rise has stopped. In other words, the time from when the water boils until the device detects boiling is long, and even though the water is actually boiling, it continues to heat and releases a large amount of water vapor. If a large amount of water vapor is released indoors, the humidity will increase, which will impair indoor comfort and cause condensation on surrounding furniture, walls, etc. Moreover, power consumption increases unnecessarily and resources are wasted.

[0006] Furthermore, as mentioned above, in the conventional boiling control device for electric jar pots, a heat retention temperature considerably lower than the boiling point is predetermined as a fixed value. This was because it would be a problem if the atmospheric pressure dropped and the boiling point became lower than the set heat retention temperature. Therefore, when the user needed hot water, it was necessary to perform operations such as boiling it again.

[0007] The present invention solves the above-mentioned problems with the conventional configuration, and when boiling of the liquid is detected, the power supply to the heater is immediately stopped to reduce the amount of steam released to the outside. The primary objective is to provide a boiling control device that can.

A second object of the present invention is to provide a boiling control device that can set the boiling point and the heat retention point to almost the same temperature and keep the temperature at the boiling point at all times.

[0009] A third object of the present invention is to provide a boiling control device that switches the power supply from the main heater to the sub-heater when boiling is detected, thereby reducing the amount of steam released to the outside and at the same time keeping the temperature at the boiling point at all times. The purpose is

0010

[Means for Solving the Problems] A first means of the present invention to achieve the first object is to provide a piezoelectric diaphragm attached to an exhaust port or an exhaust passage for discharging steam, and a piezoelectric diaphragm attached to an exhaust port or an exhaust passage for discharging steam. A boiling control system consisting of a signal amplification section that amplifies a signal, an expansion detection section that receives the output of the signal amplification section and detects an electrical signal, and a heater energization control section that controls energization to the heater based on the output of the expansion detection section. It is intended to be used as a device.

A second means of the present invention for achieving the second object is a piezoelectric diaphragm attached to an exhaust port or an exhaust passage for discharging steam, and a signal amplification device for amplifying the signal of the piezoelectric diaphragm. an expansion detection section that receives the output of the signal amplification section and detects a positive polarity electrical signal; a contraction detection section that receives the output of the signal amplification section and detects a negative polarity electrical signal; The boiling control device is comprised of a main control section that receives the output of the expansion detection section and the output of the expansion detection section, and a heater energization control section that controls energization of the heater based on a signal from the main control section.

[0012] A third means of the present invention for achieving the third object further includes a first heater for boiling water, a second heater for keeping the water warm after boiling, and an exhaust for discharging steam. a piezoelectric diaphragm attached to the mouth or the exhaust passage; a signal amplification section that amplifies the signal of the piezoelectric diaphragm; an expansion detection section that receives the output of the signal amplification section and detects a positive electric signal; a contraction detection section that receives the output of the signal amplification section and detects an electric signal of negative polarity; an operation mode storage section that stores whether the boiling operation is in progress or the heat retention operation; and an operation mode storage section that detects the outputs of the expansion detection section and the contraction detection section. A main control section that reads and writes the memory contents of the operation mode storage section, and a heater energization control section that controls energization of the first heater or the second heater based on a control signal output from the main control section. This is a boiling control device.

[0013]

[Operation] The first means of the present invention is to detect boiling by detecting the voltage generated when the piezoelectric diaphragm expands, and the boiling detection time is extremely short compared to the method that measures the temperature gradient. The amount released to the outside is very small.
It also prevents wasted power.

The second means of the present invention utilizes a piezoelectric diaphragm, similar to the second means of the present invention, and controls the on/off of the heater using both the voltage due to expansion and the voltage due to contraction. It is something that does. In other words, the liquid that has reached its boiling point is then kept at a temperature extremely close to its boiling point.

Further, in the third means of the present invention, the first means and the second means are used in combination, and when boiling is detected, the heat retention operation is immediately started, and the amount of steam released to the outside is small. Moreover, it can be kept at a temperature extremely close to the boiling point at all times.

[0016]

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, numeral 1 denotes a piezoelectric diaphragm, which is a composite structure in which an extremely thin piezoelectric ceramic plate having different expansion coefficients and a metal substrate are bonded together. This piezoelectric diaphragm 1 has conventionally been used as a piezoelectric buzzer by applying an audible frequency alternating current signal. The piezoelectric diaphragm 1 has the property that it generates a high voltage upon impact, and when a mechanical force is applied to the piezoelectric diaphragm to cause a warp, it generates a voltage corresponding to the direction of the warp. In this embodiment, the piezoelectric diaphragm 1 is attached to an exhaust port or an exhaust passage A through which steam is discharged, so that the piezoelectric diaphragm 1 receives steam heat due to boiling of liquid.

In this way, this steam heat causes the piezoelectric diaphragm 1 to
When the material expands, mechanical strain occurs due to the difference in expansion coefficients. Distortion due to this expansion appears as a positive voltage. Also, when the vapor runs out after expansion, it returns to its original room temperature, causing distortion due to contraction, which appears as a negative polarity voltage.

Reference numeral 2 denotes a signal amplifying section for amplifying the electrical signal of the piezoelectric diaphragm 1. 3 is an expansion detection unit that detects expansion of the piezoelectric diaphragm 1 from the output signal of the signal amplification unit 2;
It consists of a comparator 4 and a reference voltage source 5. Similarly, reference numeral 6 denotes a contraction detection unit that detects contraction of the piezoelectric diaphragm 1 from the output signal of the signal amplification unit 2, and includes a comparator 7 and a reference voltage source 8.
It consists of Here, the voltage value Vref of the reference voltage source 5
1 is higher than the voltage value Vref2 of the reference voltage source 8. Reference numeral 9 denotes a microcomputer that receives signals from the expansion detection section 3 and contraction detection section 6 and controls the heater circuit. The microcomputer 9 has a main control section 10 and an operation mode storage section 11.

The main control section 10 receives signals from the output 4a of the expansion detection section 3 and the output 7a of the contraction detection section 6 and operates as follows. That is, when the power is turned on, first, the boiling mode is written in the operation mode storage section 11. When a signal is received from the expansion detection section 3 for the first time in this way, this information is transmitted to the operation mode storage section 11 and acts on the heater energization control section 12 to turn off the energization of the first heater 21 for boiling water. . When the signal from the contraction detection section 6 is received after this state, it is confirmed that the operation mode storage section 11 contains information that the signal from the expansion detection section 3 has already been received, and the heater energization control section 12 is activated. and turn on the second heater 23 for keeping warm. In this case, if the operation mode storage section 11 does not have the above information, the signal from the contraction detection section 6 is ignored.

The heater energization control section 12 controlled by the signal from the main control section 10 includes two sets of relays 13 and 17.
It consists of a drive unit and its drive unit. One end of the coil 13 of the first relay that turns on and off the circuit of the first heater 21 is connected to the collector of the transistor 15. Further, the other end of the coil 13 of the relay is connected to the positive electrode of a power source 16 for driving the relay. The negative electrode of the relay driving power source 16 is at ground potential. Further, the emitter of the transistor 15 is also grounded, and the base is connected to the main control section via the resistor 14.

The coil 17 of the second relay, which turns on and off the second heater 23, has one end connected to the collector of the transistor 19, and the other end connected to the positive terminal of the relay driving power source 16. The emitter of the transistor 19 is grounded, and the base is connected to the main control section via the resistor 18. 20 is a contact point of a relay controlled by the coil 13, which turns on and off the first heater 21 for boiling water. That is, when the contact 20 is turned on, the first heater 21 is supplied with power from the commercial power supply 24. Similarly, 22 is a relay contact controlled by the coil 17 that turns on and off the second heater 23 for keeping warm. When the contact 22 is turned on, the second heater 23 is supplied with power from the commercial power supply 24 .

The operation of this embodiment will be explained below. When the circuit is turned on, the main control section 10 stores the operation mode storage section 1.
1, write information indicating that it is in boiling mode. That is, the operation mode storage section 11 is initialized. When the first heater 21 is energized and the temperature of the liquid rises, steam is generated. The piezoelectric diaphragm 1 is attached to an exhaust port or an exhaust passage A for discharging this steam so as to reliably receive the heat of this steam. Therefore, it expands upon receiving the heat of this steam and generates a positive electrical signal. This signal is amplified by the signal amplifier 2, and a signal having a waveform as shown in FIG. 2 is output. When the piezoelectric diaphragm 1 is not outputting a signal, the signal amplification unit 2 outputs a voltage value Vref1 of the reference voltage source 5 and a reference voltage source 8.
It is designed to output a value exactly in the middle of the voltage value Vref2.

The comparator 4 receives the reference voltage Vre of the reference voltage source 5.
f1 is compared with the output 2a of the amplifier 2, and normally a high level signal is output to the output 4a, but the reference voltage Vref1
When the output 2a of the amplifier 2 becomes a higher voltage than the output 2a, a low level signal is output to the output 4a. In other words, when the liquid reaches its boiling point and steam is vigorously jetted out, and the piezoelectric diaphragm 1 expands due to the heat of this steam, the output 4a becomes low level. When the main control section 10 receives this signal, it rewrites the information in the operation mode storage section to the warming mode, and at the same time sends a signal to turn off the coil 13 of the first relay of the heater energization control section 12. In this way, the first heater 21 is turned off.

When the temperature of the liquid decreases and the vapor no longer hits the piezoelectric diaphragm 1, the piezoelectric diaphragm 1 releases heat and contracts. In this way, the piezoelectric diaphragm 1 generates an electric signal of negative polarity. This signal is sent to the signal amplification section 2, and a negative polarity signal as shown in FIG. 2 is generated at the output 2a. Shrinkage detection section 6
The comparator 7 constituting the reference voltage V of the reference voltage source 8
ref2 and the output 2a of the signal amplification section 2 are compared, and when the output 2a of the signal amplification section 2 becomes a lower voltage than the reference voltage Vref2, a low level signal is output to the output 7a. When the main control section 10 receives this signal, the operation mode storage section 11
After confirming that the information indicates the heat retention mode, the second coil 17 of the heater energization control section 12 is operated to turn on the second heater 23. In this way, the second heater 2
3 is turned on. If you are exposed to liquid vapor again,
The main controller 10 operates to turn off the second heater 23.

As described above, according to the boiling control device of this embodiment, the expansion detection section 3 quickly detects the expansion of the piezoelectric diaphragm 1 due to the steam starting to boil, and the main control section 10 controls the first heater 21. Because the electricity is turned off, almost no steam is produced, and electricity is not wasted. Also, during heat retention, the expansion detection unit 3 quickly detects that the piezoelectric diaphragm 1 expands due to the steam that is starting to boil, and the main control unit 10 stops energizing the second heater 23, so that when steam no longer comes out. Since the contraction detection section 6 quickly detects the contraction of the piezoelectric diaphragm 1 and the main control section 10 starts energizing the second heater 23, the hot water is kept warm at a high temperature near the boiling point.

[0026]

Effects of the Invention As is clear from the above embodiments, according to the first means of the present invention, almost no steam leaks outside even when water is boiled, and there is no fear that surrounding objects will be affected by moisture.
Since boiling does not continue unnecessarily, it is possible to provide a boiling control device that can use electric power effectively.

According to the second means of the present invention, it is possible to provide a boiling control device in which almost no steam leaks to the outside, there is no fear that surrounding objects will be affected by moisture, and water that is just barely boiling can be used at any time. .

According to the third means of the present invention, almost no steam leaks to the outside, so there is no fear that surrounding objects will be affected by moisture, and moreover, electric power can be used effectively because boiling does not continue unnecessarily. It is possible to provide a boiling control device that, after once boiling, quickly shifts to heat retention and allows hot water just below the boiling point to be used at any time.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram of a boiling control device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of a control circuit of a boiling control device according to an embodiment of the present invention.

[Figure 3] Control circuit diagram of conventional boiling control device

[Fig. 4] Operation explanatory diagram of a control circuit of a conventional boiling control device

[Explanation of symbols]

1 Piezoelectric diaphragm 2 Signal amplification section 3 Expansion detection part 6 Shrinkage detection part 21 First heater 23 Second heater

Claims (3)

[Claims] Claim 1: A piezoelectric diaphragm attached to an exhaust port or an exhaust passage for discharging steam, a signal amplification section for amplifying the signal of the piezoelectric diaphragm, and an electric signal detected by receiving the output of the signal amplification section. A boiling control device comprising an expansion detection section and a heater energization control section that controls energization to the heater based on the output of the expansion detection section. 2. A piezoelectric diaphragm attached to an exhaust port or an exhaust passage for discharging steam, a signal amplification section for amplifying the signal of the piezoelectric diaphragm, and a positive electric signal in response to the output of the signal amplification section. an expansion detection section that detects an electric signal of negative polarity in response to the output of the signal amplification section; a main control section that receives the output of the contraction detection section and the output of the expansion detection section; The boiling control device includes a heater energization control section that controls energization to the heater based on a signal from the main control section. 3. A first heater for boiling water, a second heater for keeping the water warm after boiling, a piezoelectric diaphragm attached to an exhaust port or an exhaust passage for discharging steam, and the piezoelectric diaphragm. an expansion detection section that receives the output of the signal amplification section and detects a positive polarity electrical signal; and a contraction detection section that receives the output of the signal amplification section and detects a negative polarity electrical signal. a detection unit, an operation mode storage unit that stores whether the boiling operation is in progress or a heat retention operation, and a main control unit that receives outputs from the expansion detection unit and the contraction detection unit and reads and writes the contents of the operation mode storage unit; A boiling control device comprising a heater energization control section that controls energization of the first heater or the second heater based on a control signal output from the main control section.