JP4103237B2 - Electric water heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a water heater for an electric water heater that heats and retains a liquid contained in a container.
[0002]
[Prior art]
  Conventionally, this type of electric water heater is as follows. That is, the bottomed cylindrical container is brought into contact with a heating means for heating and keeping the liquid in the container (consisting of a first heating means for heating and a second heating means for heating and keeping warm). Yes. Further, the temperature detecting means abutted on the container detects the temperature in the container, and the following operation is performed by a value obtained by directly converting the detected temperature into an electric signal. That is, when a temperature below the boundary temperature at which automatic water heating is performed is detected, the heating means is driven to start water heating. Thereafter, the boiling detection means detects that the temperature gradient has become gentler than the predetermined temperature rise gradient by the input of the temperature detection means, and determines that it is boiling, and stops the driving of the heating means.
[0003]
[Problems to be solved by the invention]
  However, with such a conventional configuration, it has become difficult to reliably detect boiling and end the boiling time in a short time.
[0004]
  That is, in recent years, electric water heaters have a large capacity and use high-watt heaters, and thus the swinging of the sensor due to convection in the container has further increased.
[0005]
  FIG. 11 shows this state simply, but the temperature detecting means follows the fluctuation of the water temperature and rises while shaking. In such a situation, the time (T) rising for each predetermined unit temperature (= T) is measured, and when this time becomes longer than a certain reference value, boiling is detected, and the conventional configuration remains as shown in FIG. In some cases, a long time such as T4 is counted, which may cause false detection of boiling.
[0006]
  On the other hand, if it is going to prevent this, since it is necessary to set the reference value for judging this boiling longer (here, T4 or more), the boiling time becomes longer and a large amount of steam is generated. When used nearby, it sometimes causes problems such as damaging walls.
[0007]
[Means for Solving the Problems]
  In order to solve the above problems, the present invention provides a container for storing a liquid, heating means for heating or keeping the temperature of the liquid in the container, and detecting the temperature in the container.And a delay circuit that absorbs sudden temperature changes at the output sectionTemperature detection means and boiling detection means for detecting that the temperature has boiled at the detected temperature of the temperature detection meansAnd a predetermined temperature drop is detected by the input of the temperature detecting means. Then, reset means for resetting the delay circuitIs provided.
[0008]
  Thus, a stable temperature rise gradient is supplied to the boiling detecting means by electrically smoothing the detected temperature of the temperature detecting means shown in FIG.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a container for storing a liquid, a heating means for heating or keeping a temperature of the liquid in the container, and a temperature in the container are detected.And a delay circuit that absorbs sudden temperature changes at the output sectionTemperature detection means and boiling detection means for detecting that the temperature has boiled at the detected temperature of the temperature detection meansAnd reset means for resetting the delay circuit when a predetermined temperature drop is detected by the input of the temperature detecting meansIs provided.
[0010]
  Claims2The described invention is provided with power detection means for driving the reset means when the power is turned off.
[0011]
  And claims3The described invention is configured to prohibit the drive of the boiling detection means for a predetermined time immediately after the power is turned on.
[0012]
  As described above, the present invention can supply a smooth and smoothly stable temperature rise gradient to the boiling detection means by electrically smoothing the detection temperature of the temperature detection means, so that stable boiling detection can be easily performed in a short time. It can be realized with a configuration.
[0013]
  In addition, this delay circuit can detect a stable rising gradient as the temperature rises, but it has a sample-and-hold configuration that is unsuitable for following the temperature once it has reached the temperature. Therefore, when a drop in temperature is detected, the delay circuit is forcibly reset to lower the sample hold level so that even if there is a sudden temperature change, stable boiling detection is performed. be able to.
[0014]
  In addition, when the power is turned on, the boiling detection means is not driven until the stable temperature level of the delay circuit is maintained, so that the boiling can be reliably detected.
[0015]
  From the above, it is possible to provide a high-quality electric water heater that is easy to use.
[0016]
【Example】
  (referenceExample 1)
  Hereinafter, the present inventionFirst referenceExamples are illustrated in the accompanying drawings. FIG. 1 illustrates the present invention.First reference1 is a block diagram of an electric water heater showing an example, 1 is a container for storing liquid, 2 is a first heating means that contacts the container 1 and heats the liquid in the container, and similarly heats and keeps the liquid in the container. The heating means is a generic term for the second heating means having a smaller wattage output than the first heating means.
[0017]
  Reference numeral 3 denotes a temperature detection means, which is a temperature detection element 3a that is brought into contact with the container 1 to detect the temperature of the liquid in the container, a reference resistor 3b for converting the resistance value into an electric signal, and the electric signal can be determined. It is basically composed of an AD converter 3c that performs conversion into a digital signal. Further, the temperature detecting means 3 constitutes a delay (CR) circuit that stabilizes the input of the temperature detecting element 3a through the resistor 3d and the capacitor 3e between the temperature detecting element 3a and the AD converter 3c. ing. This CR absorbs a sudden change of the temperature detecting element 3a. However, the larger the time constant of the CR, the more stable the input of the temperature detecting means, but the temperature rising gradient becomes gentle at the same time as boiling. It will be difficult to become loose at any point.referenceIn the example, this time constant is set to about 6 seconds to realize stable boiling detection).
[0018]
  4 is a boiling detection means, and the input of the temperature detection means 3 isreferenceIn the example, the range of about 30-120 ° C is the unit temperature width (thisreferenceIn the example, the temperature is incremented by about 0.5 ° C., the time every time the unit temperature rises is measured, and the boiling is detected by determining the time.
[0019]
  5 is a control means, 6 is a heating start means for forcibly turning on the heating means 2 by a switch input or the like to start boiling water, and 7 is a display means for displaying the current operation by a sound such as a buzzer and light such as an LED. is there. The control means 5 is configured to control the display means 7 simultaneously with the start of boiling water by the output of the boiling detection means 4, the output of the temperature detection means 3, and the output of the heating start means 6.
[0020]
  FIG. 2 shows a flowchart of a program stored in the microcomputer that specifically realizes the operation of the boiling detection means 4 in the first invention, and the operation will be described.
[0021]
  When the electric water heater is turned on and the water heating is started by some means, the heating means 2 is driven to start the water heating (step S1). Next, the detection temperature at which the temperature detection means 3 starts the boiling detection measurement (thisreferenceIn the example, it is determined whether or not the temperature has reached or exceeded (step S2). Even if this detection start temperature is not particularly limited, it is possible to detect boiling.
[0022]
  When a temperature equal to or higher than the detection start temperature is detected in step S2, timing is started after the value of the counter for measuring the temperature rise is cleared (steps S3 and S4). Then, when the increase in the unit temperature range is detected in step S5, the value of the counter which has been timed until that time is multiplied by N times (this time in step S6).referenceIn the example, a value obtained by doubling the value is stored as a reference value 1, and the value of the counter is cleared in step S7, and the time for the next rise of the unit temperature width is measured (steps S8 and S9). If an increase in the unit temperature width is detected in step S9, it means that a gentle temperature gradient for detecting boiling has not yet been detected. Therefore, in order to detect the next increase in the unit temperature width, the process returns to step S7 to clear the counter value. Measure again from the location.
[0023]
  On the other hand, when an increase in the unit temperature range is not detected in step S9, the current value of the counter is compared with the reference value 1 set in step S6, and if the reference value 1 is larger, the process returns to step S8 to continue timing. (Step S10). If the value of the counter is larger in step S10, it is considered that the temperature rise gradient becomes gentle and boiling is detected, and in step S11, the heating means 2 is stopped, and the heat retaining operation is started.
[0024]
  In this way, since the value of the reference value 1 for detecting boiling with a simple configuration can be set to a time as short as twice the unit temperature rise time, the boiling time can be shortened and stably performed. it can.
[0025]
  BookreferenceIn the example, the heating means is described for boiling water, but the same effect can be obtained not only by the first heating means but also by heating combined with the second heating means. .
[0026]
  Also bookreferenceIn the example, the heating means is stopped simultaneously with the detection of boiling. However, after the boiling detection, the heating means is turned on after extending the boiling state for a certain period of time (2 to 3 minutes) in order to remove chalk. It can also be configured to stop.
[0027]
  Also bookreferenceIn the example, the reference resistor 3b of the temperature detecting means 3 is controlled by one. However, when more accurate temperature detection is required, or in order to simplify the program configuration, a plurality of reference resistors are used. It can also be configured to detect by switching. At this time, the ground side of the reference resistor is separated from the circuit, and only the necessary reference resistor is connected when necessary.
[0028]
  (referenceExample 2)
  The second of the present inventionreferenceAn example will be described with reference to FIGS. 3, 4 and 5. The firstreferenceThe same components as those described in the examples are denoted by the same reference numerals, and the description thereof is omitted.
[0029]
  Figure 3 shows the bookreferenceIt is a block diagram which shows the structure of an example, 1streferenceThe difference from the example is that a disconnecting means 8 for disconnecting the operation of the capacitor 3e of the delay circuit constituting the temperature detecting means 3 is provided and connected only when the boiling detecting means 4 reads the output of the temperature detecting means 3 It is the point which constituted so.
[0030]
  4 and 5BoilThe flowchart of the program memorize | stored in the microcomputer which implement | achieves concretely operation | movement of the detection means 4, the control means 5, and the cutting | disconnection means 8 was shown, FIG. 4 shows whole operation | movement and FIG. Show. This will explain the operation.
[0031]
  When the electric water heater is turned on in FIG. 4, first, the temperature detection process shown in FIG. 5 is performed (step S21). In step S61, the cutting means 8 is turned off and the capacitor 3e is connected.referenceIn the example, about 2 ms). Thereafter, temperature input (temperature input 1) for boiling detection is performed (step S63), and the cutting means 8 is turned on to disconnect the capacitor 3e from the circuit (step S64).
[0032]
  Next, it is determined whether or not the unit temperature has increased (step S65). If a unit temperature rise is detected here, the setting state of the start f (flag) is determined in step S66. This start f is used to determine whether or not the detection start temperature has been reached, and is set and reset during the operation shown in FIG.
[0033]
  If the start f is set, the detection start temperature has been reached. If the unit temperature increase is detected in step S65, the counter value at that time is stored in the comparison value 1 (step S67), and step S68. The counter is cleared and the next unit temperature rise is started (step S69). If the start f is not set, the detection start temperature has not yet been reached, so the counter is cleared without storing the comparison value 1 and the next unit temperature rise is started. On the other hand, when no increase in the unit temperature range is detected in step S65, the counter continues counting (step S69).
[0034]
  Next, in step S70, the value of the comparison value 1 is a predetermined value (thisreferenceIn the example, it is determined whether it is smaller than 0.7 seconds), and if it is smaller, it is determined that there is no water in the container, and the process proceeds to the empty cooking mode (described later). When it is equal to or greater than the predetermined value in step S70, it is a stable time for reading the temperature input (temperature input 2) for determining the operation mode or the like in step S71 (this time)referenceAfter waiting, the temperature input 2 is input and stored in the comparison value 2 (steps S72 and 73).
[0035]
  After the above process is completed, the process returns to the process of FIG. In step S22, the first predetermined temperature (thisreferenceIn the example, it is determined whether the temperature is about 90 ° C. or higher, and the mode is branched. Here, when the temperature is equal to or higher than the first predetermined temperature, the operation in the heat retention mode after step S40 is performed. On the other hand, when the temperature is lower than the first predetermined temperature, the start f is reset (step S23), the display means 7 is displayed as when boiling, and the heating means 2 is driven to start boiling (step S24).
[0036]
  Next, in order to accurately measure the unit temperature width increase time, the temperature input 2 is read until the unit temperature width increases once, and when the increase is detected, the counter is cleared (steps S25 and S26).
[0037]
  In step S28, the temperature detection process is performed, and based on the result, it is determined whether or not the detection start temperature has been reached (step S29). Here, when it is lower than the detection start temperature, it waits until it becomes equal to or higher than the detection start temperature. On the other hand, when a temperature equal to or higher than the detection start temperature is detected in step S29, the value of the comparison value 1 for storing the unit temperature rise measurement time is reset and the start f is set (step S30). Next, the temperature detection process is performed again (step S32), and the temperature detection process is repeated until the comparison value 1 is set (step S34). When the comparison value 1 has a value in step S34, the reference value 1 is set based on the value (step S35).
[0038]
  Further, the temperature detection process is performed in step S37, the value of the counter for measuring the unit temperature width increase is compared with the reference value 1 set in step S35, and if the reference value 1 is larger, the process returns to step S37. Then, the temperature detection process is continued (step S39). If the value of the counter is larger in step S39, it is considered that boiling has been detected, and the process proceeds to the heat retention mode processing in step S40 and subsequent steps.
[0039]
  If it transfers to heat retention mode, the heating means 2 will be turned off and the display at the time of heat retention will be performed (S40, S41). Next, it is determined whether or not the heating start means 6 has been input (step S43). If there is an input, the process returns to step S23 to perform the water heater mode again. If there is no input in step S43, the temperature detection process is performed. If the detected value of the comparison value 2 is lower than the first predetermined temperature, the process returns to step S23 to perform the water heating mode again. On the other hand, if the temperature is equal to or higher than the first predetermined temperature, the second predetermined temperature (thisreferenceIf it is lower than the second predetermined temperature, the second heating means is energized, and if it is higher than the second predetermined temperature, the process returns to step S40 as it is (steps S43 to S47).
[0040]
  The above shows the operation of the basic electric water heater. In addition, when shifting to the above-described empty cooking, the processing after step S53 is performed. That is, the display means 7 is changed to the display in the empty cooking mode, and the heating means 2 is stopped (steps S53 and S54). And it waits for the input of the heating start means 6, and if there is an input, it will transfer to step S23 and it is comprised so that a kettle may be started (step S56).
[0041]
  During these processes, the power source is monitored at regular intervals to check whether the power source has been turned off (steps S27, S31, S36, S42, S55). If it is confirmed that the power is turned off, all the loads are turned off in step S51, and the system is on standby until the power is restored. When the power is restored, the processing from step S21 is performed.
[0042]
  As can be seen from this configuration, the resistor 3d and the capacitor 3e constituting the CR circuit have a large time constant as described above, and the direction in which the voltage is increased (temperature increase) is stable, but the direction in which the voltage is decreased (temperature decrease) is the capacitor. It takes time to discharge the stored charge of 3e and cannot cope with a rapid temperature change. So bookreferenceBy making the configuration as shown in the example, the boiling detection is performed with a configuration in which a delay circuit is connected, so that the boiling time can be shortened and stably performed, and at the same time, the delay circuit is used for temperature detection other than the boiling detection. Since the detection is performed with the configuration separated from the above, the same detection as in the conventional case is possible, so that it is possible to accurately and stably detect a thing that requires a rapid temperature change detection.
[0043]
  BookreferenceIn the example, the capacitor 3e is configured as a control for separating the ground side from the circuit, but the same effect can be obtained by hand in the configuration for separating the positive side of the capacitor.
[0044]
  Also bookreferenceIn the example, the time during which the cutting means 8 is turned on is about 2 mS. However, the longer this time is, the more stable the temperature input is. Therefore, it can be stabilized by making it as long as possible.
[0045]
  Also bookreferenceIn the example, empty cooking detection is performed with the temperature input 1 (when the delay circuit is connected), but it can also be performed based on the temperature input 2.
[0046]
  (Example1)
  First of the present invention1This embodiment will be described with reference to FIGS. 6 and 7. FIG. The secondreferenceThe same components as those described in the examples are denoted by the same reference numerals, and the description thereof is omitted.
[0047]
  FIG. 6 is a block diagram showing the configuration of the present embodiment.referenceThe difference from the example is that a discharge resistor 3f connected in parallel with the capacitor 3e of the delay circuit constituting the temperature detecting means 3 and configured to discharge the charge stored in the capacitor 3e, and the discharge resistor 3f are controlled. The reset means 9 is provided, and the reset means is driven when the control means 5 detects a temperature drop.
[0048]
  FIG. 7 shows the operation of the temperature detection process of the program stored in the microcomputer that specifically realizes the operations of the boiling detection means 4, the control means 5, the cutting means 8 and the reset means 9 in the third invention. This will explain the operation. The overall operation is the same as that shown in FIG.
[0049]
  When the operation shifts to the temperature detection process as shown in the flowchart of FIG. 4, the following operation (FIG. 7) is performed.
[0050]
  That is, the input is stabilized in step S83 with the disconnecting means 8 turned off in steps S81 and S82 and the capacitor 3e connected, and the reset means 9 turned off and the discharge resistor 3f disconnected from the circuit. Wait for a time (about 2 ms in this embodiment). Thereafter, the temperature input 1 is performed (step S84), the cutting means 8 is turned on, and the capacitor 3e is disconnected from the circuit (step S85).
[0051]
  Next, it is determined whether or not the unit temperature has increased (step S86). If a unit temperature increase is detected here, the setting state of the start f is determined in step S87. If the start f is set, the detection start temperature has been reached. If the unit temperature increase is detected in step S86, the counter value at that time is stored in the comparison value 1 (step S88), and step S89. The counter is cleared and the next unit temperature rise is started (step S90). If the start f is not set, the detection start temperature has not yet been reached, so the counter is cleared without storing the comparison value 1 and the next unit temperature rise is started. On the other hand, if no increase in the unit temperature range is detected in step S86, the counter continues counting (step S90).
[0052]
  Next, in step S91, it is determined whether or not the value of the comparison value 1 is smaller than the predetermined value. If it is small, it is determined that there is no water in the container, and the process proceeds to the empty cooking mode. If it is equal to or greater than the predetermined value in step S91, after waiting for a stable time (about 1 ms in this embodiment) to read the temperature input 2 in step S92, the temperature input 2 is input and stored in the comparison value 2 (step S91). S93, 94).
[0053]
  Next, in step S95, the comparison value 2 is compared with a reference value 2 (described later) that has been measured and stored last time, and the comparison value 2 has a predetermined temperature (about 2 degrees in this embodiment) rather than the reference value 2. If it is determined that the value is lower than the above, the counter value being counted is cleared and the start f is reset (steps S96 and S97). Further, the resetting means 9 is turned on to connect the discharge resistor 3f, and at the same time the disconnecting means 8 is turned off to connect the capacitor 3e to discharge the electric charge of the capacitor 3e for a second predetermined time (in this embodiment, about 5 seconds) (steps S98 and S99). When the second predetermined time elapses, the resetting means 9 is turned off and the cutting means 8 is turned on simultaneously to disconnect the discharge resistor 3f and the capacitor 3e from the circuit (step S100). Then, the comparison value 2 is stored as the next reference value 2 (step S101). On the other hand, if a temperature drop is not detected in step S95, the process proceeds directly to step S101. Thus, the temperature detection process is completed, and the whole operation shown in FIG. 4 is resumed.
[0054]
  With the above configuration, even when a temperature drop due to the addition of water is detected as described above, the charge stored in the capacitor 3e is discharged, so that the detected temperature of the temperature detecting element 3a can be accurately set. Since the start f is reset in step S97, the boiling detection operation is performed because the flow returns to step S25 regardless of the position in the boiling water shown in FIG. Since this is done from the beginning, boiling can be reliably detected.
[0055]
  Note that the second predetermined time can be shortened by making the discharge resistance 3f as small as possible.
[0056]
  (Example2)
  First of the present invention2This embodiment will be described with reference to FIGS. The first1The same reference numerals are used for the same components as those described in the embodiment, and the description thereof is omitted.
[0057]
  FIG. 8 is a block diagram showing the configuration of this embodiment.1The difference from this embodiment is that a power source detection means 10 is provided. The power source detection means 10 comprises an AC power source 10a, a DC power source 10b generated from the AC power source, and a capacitor 10c for stabilizing the DC power source. Furthermore, one side of the AC power supply 10a is attenuated by resistors 10d, 10e, and 10f, and the upper and lower limits are clipped by the diodes 10g and 10h, so that the DC power supply + (diode Vf) to ground-(diode Vf) To generate a square wave. On the other hand, when the power supply is turned off, the supply from the AC power supply 10a is lost, but the DC power supply 10b maintains its potential for a while due to the charge stored in the capacitor 10c. At this time, a DC voltage obtained by dividing the voltage of the DC power supply 10b by the resistors 10e and 10f is output. The determination means 10i detects this difference. Then, the determination unit 10i turns on the reset unit 9 and turns off the cutting unit 8 when the power-off is detected.
[0058]
  FIG. 9 shows the operation of the program stored in the microcomputer that specifically realizes the operations of the boiling detection means 4, the control means 5, the cutting means 8, the resetting means 9, and the power supply detection means 10 in the fourth invention. This will explain the operation. The temperature detection processing operation is the same as that in FIG.
[0059]
  When the electric water heater is turned on in FIG. 9, the reset means 9 is turned off in step S111 to inhibit the discharge of the capacitor 3e.
[0060]
  Next, the temperature detection process shown in FIG. 7 is performed (step S112). The operation is an example1As explained in. When this temperature detection process ends, in step S113, it is determined whether the temperature is equal to or higher than the first predetermined temperature based on the value of the comparison value 2, and the mode is branched. Here, when the temperature is equal to or higher than the first predetermined temperature, the operation in the heat retention mode after step S131 is performed. On the other hand, when the temperature is lower than the first predetermined temperature, the start f is reset (step S114), the display means 7 is displayed as when boiling, and the heating means 2 is driven to start boiling (step S115).
[0061]
  Next, in order to accurately measure the unit temperature width rise time, the temperature input 2 is read until the unit temperature width rises once, and when the rise is detected, the counter is cleared (steps S116 and S117).
[0062]
  In step S119, the temperature detection process is performed, and based on the result, it is determined whether or not the temperature is equal to or higher than the detection start temperature (step S120). Here, when it is lower than the detection start temperature, it waits until it becomes equal to or higher than the detection start temperature. On the other hand, when a temperature equal to or higher than the detection start temperature is detected in step S120, the value of comparison value 1 for storing the unit temperature rise measurement time is reset and the start f is set (step S121). Next, the temperature detection process is performed again (step S123), and the temperature detection process is repeated until the comparison value 1 is set (step S125). When the comparison value 1 has a value in step S125, the reference value 1 is set based on the value (step S126).
[0063]
  Further, the temperature detection process is performed in step S128, the counter value during measurement of the unit temperature width increase is compared with the reference value 1 set in step S126, and if the reference value 1 is larger, the process returns to step S128. The temperature detection process is continued (step S130). If the value of the counter is larger in step S130, it is considered that boiling has been detected, and the process proceeds to the heat retention mode processing in step S131 and thereafter.
[0064]
  When shifting to the heat retention mode, the heating means 2 is turned off, and the display operation during the heat retention is performed (S131, S132). Next, it is determined whether or not the heating start means 6 has been input (step S134). If there is an input, the process returns to step S114 to perform the water heating mode again. If there is no input in step S134, the temperature detection process is performed. If the detected value of the comparison value 2 is lower than the first predetermined temperature, the process returns to step S114 and the hot water mode process is performed again. On the other hand, if the temperature is equal to or higher than the first predetermined temperature, the second heating temperature is compared with the second predetermined temperature. If the temperature is lower than the second predetermined temperature, the second heating means is energized. (Steps S135 to S138). The above is the operation of the basic electric water heater. In addition, the processing of the current cooking transition event is the same as described above, and is omitted.
[0065]
  During these processes, the power supply is monitored at regular intervals to check whether the power is turned off (steps S118, S122, S127, and S133). If it is confirmed that the power is turned off by the above method, in step S139, all the loads are turned off, and at the same time, the resetting means 9 is turned on, and the cutting means 8 is turned off to wait until the power is restored. When the power is restored, the processing from step S111 is performed.
[0066]
  By configuring as described above, the electric charge stored in the capacitor 3e is discharged even when the power is turned off, assuming a temperature drop, so water is added when the power is turned off, and the electric charge still stored in the capacitor 3e is naturally Even when the power source is turned on again in a short time that cannot be fully discharged, it is possible to reliably obtain a temperature rise gradient by discharging it reliably.
[0067]
  In this embodiment, the capacitor 3e is discharged at the same time as the power is turned off. However, considering an instantaneous voltage drop (instantaneous power failure) or the like, it is preferable that the capacitor 3e be operated for a while after the power is turned off. It is also possible to increase the capacity to increase the instantaneous power failure tolerance of the microcomputer.
[0068]
  (Example3)
  First of the present invention3This embodiment will be described with reference to FIG. The first2The same reference numerals are used for the same components as those described in the embodiment, and the description thereof is omitted.
[0069]
  FIG. 10 shows the operation of the program stored in the microcomputer that specifically realizes the operations of the boiling detection means 4, the control means 5, the cutting means 8, the resetting means 9, and the power supply detection means 10 in the fifth invention. This will explain the operation. The temperature detection processing operation is the same as that in FIG.
[0070]
  In FIG. 10, when the electric water heater is turned on, the power supply f (flag) is set (step S151). This flag is used to determine whether or not the kettle has been started immediately after the power is turned on, and is configured to be reset once the warming operation is started. Next, in step S152, the reset means 9 is turned off to prohibit the discharge of the capacitor 3e.
[0071]
  Next, the temperature detection process shown in FIG. 7 is performed (step S153). The operation is an example2As explained in. When this temperature detection process ends, in step S154, it is determined whether the temperature is equal to or higher than the first predetermined temperature based on the value of the comparison value 2, and the mode is branched. Here, when the temperature is equal to or higher than the first predetermined temperature, the operation in the heat retention mode after step S176 is performed. On the other hand, when the temperature is lower than the first predetermined temperature, the start f is reset (step S155), the display means 7 is displayed as when boiling, and the heating means 2 is driven to start boiling (step S156).
[0072]
  Next, in step S157, it is determined whether the power source f is set. If the power supply f is set, the disconnecting means 8 is turned off in step S159 to charge the capacitor 3e, and a first predetermined time (about 5 seconds in this embodiment) is waited. On the other hand, if the power supply f is not set, this process is not performed and the process proceeds to the next step.
[0073]
  Next, in order to accurately measure the unit temperature width increase time, the temperature input 2 is read until the unit temperature width increases once, and the counter is cleared when the increase is detected (steps S161 and S162).
[0074]
  In step S164, the temperature detection process is performed, and based on the result, it is determined whether or not the detection start temperature has been reached (step S165). Here, when it is lower than the detection start temperature, it waits until it becomes equal to or higher than the detection start temperature. On the other hand, when the detection start temperature or higher is detected in step S165, the value of the comparison value 1 for storing the unit temperature rise measurement time is reset and the start f is set (step S166). Next, the temperature detection process is performed again (step S168), and the temperature detection process is repeated until the comparison value 1 is set (step S170). When the comparison value 1 has a value in step S170, the reference value 1 is set based on the value (step S171).
[0075]
  Further, the temperature detection process is performed in step S173, the value of the counter that is measuring the unit temperature width increase is compared with the reference value 1 set in step S175, and if the reference value 1 is larger, the process returns to step S173. Then, the temperature detection process is continued (step S175). If the value of the counter is larger in step S175, it is regarded that boiling has been detected, and the process proceeds to the heat retention mode processing in step S176 and subsequent steps.
[0076]
  The processing after shifting to the heat retention mode is the same as the content shown in FIG. Further, the processing at the time of empty cooking and the processing at power-off are the same as in FIG.
[0077]
  With the configuration as described above, since the capacitor 3e when the power is turned on does not store charges up to the partial pressure of the temperature detection element 3a and the reference resistor 3b, an accurate temperature rise gradient cannot be obtained, so the boiling detection process is performed. By configuring so as not to be performed, stable boiling detection can be performed.
[0078]
【The invention's effect】
  As described above, according to the first aspect of the present invention, since the temperature detection means can be electrically leveled to provide a smooth and smoothly stable temperature rise gradient to the boiling detection means, the temperature sensor fluctuates. By removing the influence, stable boiling can be detected in a short time, and it is possible to realize with a simple configuration that the amount of jetted steam can be reduced.
[0079]
  Also waterWhen a temperature drop due to addition is detected, the delay circuit can be reset to stabilize the temperature rise gradient, thereby accurately detecting the boiling.
[0080]
  Claims2The described invention can stabilize the temperature rise gradient even when water is added after the power is turned off and the power is turned on again, so that it is possible to reliably detect boiling with a simple configuration.
[0081]
  And claims3Since the described invention is configured not to drive the boiling detection means until the delay circuit moves stably when the power is turned on, it is possible to reliably detect the boiling.
[0082]
  From the above, it is possible to provide a high-quality electric water heater that is easy to use.
[Brief description of the drawings]
FIG. 1 shows the first of the present invention.referenceBlock diagram of an example electric water heater
FIG. 2 is a flowchart showing the overall operation of the electric water heater.
FIG. 3 shows the second of the present invention.referenceBlock diagram of an example electric water heater
FIG. 4 is a flowchart showing the overall operation of the electric water heater.
FIG. 5 is a flowchart showing the operation of the temperature detection processing unit of the electric water heater.
FIG. 6 shows the first of the present invention.1Block diagram of an electric water heater of the embodiment of
FIG. 7 is a flowchart showing the operation of the temperature detection processing unit of the electric water heater.
FIG. 8 shows the first of the present invention.2Block diagram of an electric water heater of the embodiment of
FIG. 9 is a flowchart showing the overall operation of the electric water heater.
FIG. 10 shows the first of the present invention.3The flowchart which shows the whole electric water heater operation | movement of the Example of this
FIG. 11 is a diagram showing a temperature rise gradient of a conventional electric water heater
[Explanation of symbols]
  1 container
  2 Heating means
  3 Temperature detection means
  4 Boiling detection means
  8 Cutting means
  9 Reset means
  10 Power supply detection means

Claims (3)

A container for storing the liquid, a heating means for heating or keeping the temperature of the liquid in the container, a temperature detection means having a delay circuit for detecting the temperature in the container and absorbing a sudden temperature change in the output section, electric kettle, characterized the boiling detecting means for detecting that boiling by the detection temperature of the temperature sensing means, in that a reset means for resetting said delay circuit and for detecting a predetermined temperature drop by input of said temperature detecting means . Electric kettle according to claim 1 in which the power source is characterized in that a power supply detection means for driving the reset means when it is turned off. The electric water heater according to claim 1 or 2, wherein the driving of the boiling detection means is prohibited for a predetermined time immediately after the power is turned on.

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