JP2007229216A - Electric water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric water heater capable of highly efficiently discharging as much liquid in a container as possible even if elapsing a long time after turning off a commercial power supply. <P>SOLUTION: This electric water heater is so constituted as to change over a voltage to be applied to a discharge means 5 according to the amount of liquid detected by a water amount-detecting means 12, when no commercial power supply is fed thereto. When there is a small amount of liquid left in the container 1, the discharge voltage is kept as usual, however, when there is a large amount of the liquid left in the container 1, the electric water heater lowers the discharge voltage to increase the dischargeable total amount of the liquid in the container 1 so as to efficiently discharge much liquid in the container 1 as possible, even if elapsing a long time after turning off the commercial power supply. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric water heater having a backup power source.

  A conventional electric water heater includes a backup power source that supplies power when commercial power is not supplied, an electric pump drive power source that receives the backup power source, a switching unit that switches an output of the electric pump drive power source, and a control unit. Those are known (for example, see Patent Document 1).

This is because when a hot water is started, a high voltage is supplied to the electric pump drive power source for a predetermined time so that the hot water can be discharged even when the electric pump bubbles, and the voltage is lowered after a predetermined time. Is.
JP 2003-61826 A

  However, in the conventional configuration, after the commercial power supply is turned off, the power of the backup power supply decreases with time in order to maintain the operation of the control means. For this reason, for example, when a long time elapses after the commercial power supply is turned off, there is a fear that the liquid in the container cannot be discharged by the electric pump.

  The present invention solves the above-mentioned conventional problems, and provides an electric water heater that can efficiently discharge as much liquid as possible even after a long time has passed since the commercial power supply was turned off. With the goal.

  In order to solve the above-described conventional problems, the electric water heater of the present invention is configured to switch the voltage applied to the discharge means according to the amount of liquid detected by the water amount detection means when commercial power is not supplied. It is a thing.

  As a result, when the amount of liquid in the container is small, the discharge voltage remains normal, and when the amount of liquid in the container is large, the discharge voltage is lowered to increase the total dischargeable amount of liquid in the container. As a result, even if a long time elapses after the commercial power supply is turned off, the liquid in the container can be discharged as efficiently as possible.

  The electric water heater of the present invention can efficiently discharge as much liquid as possible even after a long time has passed since the commercial power supply was turned off.

  According to a first aspect of the present invention, there is provided a container for storing a liquid, a discharge means for discharging the liquid in the container, a control means for controlling the discharge means, and a backup power supply that forms a power supply when commercial power is not supplied. A water amount detecting means for detecting the amount of liquid in the container and a discharge voltage switching means for switching the voltage applied to the discharging means, and when the commercial power is not supplied to the water amount detecting means When the amount of liquid in the container is small, the discharge voltage is kept normal and the inside of the container is maintained. If the amount of liquid in the container is large, the discharge voltage can be lowered to increase the total amount of liquid that can be discharged in the container. Efficient discharge It is possible. That is, the discharge amount per unit time discharged by the backup power supply when the commercial power supply is not supplied can be optimized according to the liquid amount in the container, and the total discharge amount can be increased.

  In the second invention, in particular, in the first invention, the switching of the voltage applied to the discharging means when the commercial power is not supplied is stored in the liquid amount detected by the water amount detecting means and the backup power source. The discharge voltage is set more accurately so that the amount of liquid in the container can be discharged as much as possible from the power of the backup power supply. The total discharge amount can be increased without reducing the per unit discharge amount as much as possible.

  In particular, according to the third invention, in the first or second invention, the voltage applied to the discharge means is divided into two stages, that is, a starting voltage at the start of discharge and a steady voltage at the time of stable discharge, and the discharge voltage switching means. By switching the start voltage and the steady voltage, applying the start voltage at the start of discharge not only stabilizes the subsequent discharge, but also optimizes the start voltage at the start of discharge. By switching to the voltage, the power loss at the start of discharge can be suppressed, and the total discharge amount can be increased.

  According to a fourth aspect of the invention, in particular, in any one of the first to third aspects of the invention, the switching of the voltage applied to the discharge means when the commercial power is not supplied is the amount of liquid detected by the water amount detection means By increasing the start-up voltage, especially when the internal pressure of the container is high immediately after boiling, it is performed according to both the time elapsed since the detection of the liquid in the container being boiled. At the same time, when a certain amount of time has passed after boiling, by suppressing the start-up voltage, the power loss at the start of discharge can be minimized and the total discharge amount can be increased.

  In the fifth invention, in particular, in any one of the first to fourth inventions, the switching of the voltage applied to the discharge means when the commercial power is not supplied depends on the amount of liquid detected by the water amount detection means. The start-up voltage is increased particularly when the internal pressure is high immediately after stopping the heat insulation operation when the commercial power supply is turned off, by performing the operation according to both the time after the commercial power supply is stopped. At the same time, when a certain amount of time has passed since the commercial power supply is turned off, the power supply loss at the start of discharge can be minimized and the total discharge amount can be increased by suppressing the starting voltage.

  In the sixth aspect of the invention, in particular, in any one of the first to fifth aspects of the invention, the switching of the voltage applied to the discharge means when the commercial power is not supplied is the amount of liquid detected by the water amount detection means. When the temperature of the liquid is lowered to some extent while increasing the starting voltage in a state where the temperature of the liquid is high and the internal pressure is high, etc. By suppressing the starting voltage, it is possible to minimize the power loss at the start of discharge and increase the total discharge amount.

  In a seventh aspect of the invention, in particular, in any one of the first to sixth aspects of the invention, the display unit has a display unit, and the voltage level applied to the discharge unit when the commercial power is not supplied is displayed on the display unit. By adopting the configuration, it is possible to inform the user that the voltage level applied to the discharge means is switched in order to increase the total discharge amount in the container as much as possible, and the usability can be improved.

  In the eighth invention, in particular, in any one of the first to seventh inventions, the user can select the switching by the discharge voltage switching means when the commercial power is not supplied. And whether to give priority to the discharge amount per unit time can be selected, and usability can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
1 to 4 show an electric water heater according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the container 1 for storing the liquid 1a has a bottomed cylindrical shape. The heating means 2 is provided in contact with the bottom surface of the container 1 and heats or keeps the liquid in the container 1, and is usually composed of two or more heaters for heating and keeping warm.

  The temperature detection means 3 is brought into contact with the bottom surface of the container 1 and is composed of a thermistor or the like. The temperature detected by the temperature detection means 3 is transmitted to the control means 6, and when the temperature is lower than about 90 ° C., for example, the control means 6 issues a command to the heating control means 7 for heating the heating means 2. When the liquid 1a is heated by controlling the heater, and the temperature gradient detected by the temperature detection means 3 becomes almost flat, it is considered that the liquid 1a in the container 1 has boiled, and the heating by the heating means 2 is terminated. In response to a command from the means 6, the heating control means 7 starts the heat insulation control by the heater for heat insulation. Then, the heat retention control is performed so that the temperature of the liquid 1a is stabilized at about 98 ° C., for example.

  The discharge control means 4 is constituted by a hot water switch or the like, and when it is turned on, drives the discharge means 5 to discharge the liquid 1a in the container 1 to the outside. The discharge means 5 is constituted by a water conduit 5a for sending liquid from the container 1 to the outside, a pump 5b in the water conduit 5a, and a motor 5c for driving the pump 5b.

  The above-described heating control means 7 performs on / off control of the heating means 2 by controlling energization to the heating means 2 and is generally configured by a relay, a triac, or the like.

  The lock release means 8 locks or unlocks the discharge operation by the discharge means 5. If the lock release means 8 does not release the lock even if the hot water switch is pressed, the discharge means 5 is The formed motor 5c is not driven and the liquid 1a is not discharged.

  The backup power source 9 serves as a power source for driving the discharge means 5 when commercial power is not supplied (during backup), and is composed of an electric double layer capacitor or the like.

  The booster 10 is configured to boost the power stored in the backup power supply 9 and then supply the power for discharging to the discharger 5.

  The charging unit 11 charges the backup power source 9 when commercial power is supplied. Thereafter, when discharging is performed when the supply of commercial power is stopped, the power stored in the backup power source 9 is boosted by the boosting unit 10 and supplied to the discharging unit 5.

  Further, the water amount detecting means 12 detects the amount of liquid in the container 1, and in this embodiment, a pair of a light emitting element and a light receiving element provided facing each other so as to sandwich the water conduit 5a. It is composed of light emitting elements 12a, 12b, 12c and light receiving elements 12d, 12e, 12f. First, when light is detected by the light receiving element 12d when the light emitting element 12a emits light, the light receiving path 5a receives light. This means that the liquid does not reach at the height where the element 12d is attached. Conversely, when the light arrival element 12d does not detect the arrival of light, the light reception element 12d of the water conduit 5a is attached. The liquid reaches the height and blocks the light. That is, when light is detected by the light receiving element when the light emitting element is lit, there is no liquid amount at the height where the light receiving element is disposed, and when light cannot be detected, The amount of liquid in the container 1 is detected because there is a liquid amount up to the height at which the light receiving element is disposed.

  The discharge voltage switching means 13 switches the voltage applied to the discharge means 5 and is applied to the discharge means 5 according to the amount of liquid detected by the water amount detection means 12 when the commercial power is not supplied. The voltage to be switched is configured to be switched. Here, the boosted voltage by the boosting means 10 is switched.

  The display unit 15 is configured by an LCD, an LED, or the like that displays the temperature in the container 1 detected by the temperature detection unit 3, the state of heating by the heating control unit 7, and the setting state of heat insulation. Further, the charging amount derived from the voltage of the backup power supply 9 is also displayed. Furthermore, when discharging is performed by the discharging means 5 when the commercial power is not supplied, the voltage level for discharging is also displayed.

  Although not shown in the figure, there is a selection unit that can select switching by the discharge voltage switching unit 13 when the commercial power is not supplied, and when the commercial power is not supplied, the discharge unit 5 is provided. In the discharge operation according to the above, it is configured to select whether to give priority to increasing the total discharge amount or to give priority to increasing the discharge amount per unit time.

  FIG. 2 shows a circuit diagram of the electric water heater of the present embodiment. The heating means 2 supplied with the commercial power source 21 includes a heating heater 2a for heating the liquid in the container 1 and a heating heater 2a. The heating control means 7 includes relay contacts 7a and 7b connected in series with the heating means 2 and the relay contacts 7a. The relay contacts 7a and 7b are closed by passing a current through the relay coils 7c and 7d.

  The temperature detecting means 3 creates a divided value by a thermistor 3a that converts the temperature into a resistance value and a voltage dividing resistor 3b. Here, in order to absorb fluctuations in the detection of the thermistor 3a caused by convection of the liquid in the container 1 or rupture of bubbles that are likely to occur before the liquid boils, and electrical external noise, the charge / discharge resistor 3d And the electrolytic capacitor 3e, and the output of these ports is changed according to the timing of detecting the temperature by the microcomputer 6a (hereinafter referred to as a microcomputer) constituting the control means 6, so that the change in the detected temperature is stabilized. It can be detected with high accuracy. In this way, the partial pressure value from which electrical external noise and fluctuation of detection of the thermistor 3a are removed as much as possible is converted into a binary code by the AD converter 3c.

  The AD converter 3c sets a range of about 10 ° C. to 130 ° C. in increments of unit temperature width (about 0.5 ° C. in the present embodiment), and outputs the temperature in binary code. Then, the time required for the binary code to change by 1 bit is detected. For example, if it takes more than a predetermined time, the temperature in the container 1 is almost flat because the liquid in the container 1 is in a boiling state. If the heating control means 7 switches from heating control to heat retention control, or if it is continuously detected that the time required for the change is within a predetermined time, for example, the liquid in the container 1 It is determined that the temperature has risen sharply because of the shortage of the amount of heat, and the heating control means 7 stops the heating.

  The discharge means 5 is constituted by a motor 5b in the circuit diagram, and the discharge control means 4 is connected in series to the hot water switch 4a, the first transistor 4b controlled by the microcomputer 6a and the first transistor 4b in the circuit diagram. The resistor 4c is used.

  The unlocking means 8 includes an unlock switch 8a that determines an output to the first transistor 4b of the microcomputer 6a, a resistor 8b, and a resistor 8c. When the lock release switch 8a is turned on, the microcomputer 6a first determines the state of the hot water switch 4a at that time based on the potential of the port of the microcomputer 6a connected to the hot water switch 4a.

  If this potential is "H", the hot water switch 4a is in an on state. Therefore, if the transistor 4b is turned on, it is dangerous because immediate discharge is performed, and the input of the lock release switch 8a is invalidated. When this potential is “L”, the hot water discharge switch 4a is in an off state, and even if the first transistor 4b is turned on, the discharge is not immediately performed. Therefore, the output of the microcomputer 6a is changed from “L” to “H”. The first transistor 4b is turned on (this state is hereinafter referred to as an unlocked state). When the hot water switch 4a is turned on in this unlocked state, a voltage divided by the resistance 4c is applied to the motor 5b, and while the hot water switch 4a is turned on, a current flows through the motor 5b, and the liquid in the container 1 flows. 1a is discharged. Further, in order to prevent the unlocked state from continuing even after the end of discharge, the potential of the hot water switch 4a in the unlocked state is in the “L” state for a third predetermined time (in this embodiment, 10 seconds). When the operation is continued, the output of the microcomputer 6a is set to "L", the first transistor 4b is turned off, and the unlocked state is released (locked state).

  In the circuit diagram, the display unit 15 includes an LCD 15a, an LED 15b, an LED 15c, and an LED 15d, a resistor 15e connected in series to the LED 15b, a resistor 15f connected in series to the LED 15c, and a resistor 15g connected in series to the LED 15d. On the LCD 15a, the temperature detected by the temperature detecting means 3 is always displayed in a digital display in increments of 5 ° C. under the control of the microcomputer 6a.

  For the LED, when the heating means 2 is performing the heating operation, the port of the microcomputer 6a connected to the resistor 15e is set to “L” to turn on the LED 15b and perform the heating operation. Is displayed. When the heating means 2 detects that the temperature rise has almost leveled off during heating, and the operation of the heating means 2 is switched from heating to heat retention, the output of the microcomputer 6a to the resistor 15e. Is switched to “H” (open) to turn off the LED 15b, and at the same time, the output to the resistor 15f is switched from “H” to “L”, and the LED 15c is turned on to indicate that the temperature is maintained. In addition, regarding the LED 15d, in the unlocked state described above, the output of the microcomputer 6a connected to the resistor 15g is switched to “L”, and the LED 15d is lit to indicate that the hot water can be discharged.

  On the circuit diagram, the water amount detection means 12 is composed of light emitting diodes 12a, 12b, and 12c on the light emitting side and phototransistors 12d, 12e, and 12f on the light receiving side, and the target phototransistor when the light emitting diodes are respectively lit. Detects the amount of water depending on whether or not is turned on. For example, when all the phototransistors are turned on, the maximum is four levels out of the four liquid level, and when only the phototransistor 12d is off, the phototransistors 12d and 12e are off. If it is, it is judged that there is almost no liquid in the container 1 at the lowest level.

  In the circuit diagram, the backup power source 9 is composed of an electric double layer capacitor 9a, and when the commercial power source 21 is supplied, the backup power source 9 is charged by the charging means 11 that charges at a constant current, and the ground and the electric double layer capacitor The voltage between the positive terminals of 9a is controlled so as to keep about 2V. When the lock release switch 8a is pushed and the lock release state is entered when the commercial power source 21 is not supplied, the electric power stored in the electric double layer capacitor 9a is boosted by the boosting means 10 and is supplied to the motor 5b. It is configured to supply power.

  Further, the discharge voltage switching means 13 is configured to switch the voltage boosted by the boosting means 10 in accordance with the liquid amount detected by the water amount detecting means 12. Here, regarding the capacity of the electric double layer capacitor 9a, it is considered that at least 1F or more is necessary in consideration of operating the motor 5b, and should preferably be around 50F. The larger the capacity, the larger the commercial power supply 21 The amount of liquid that can be discharged by the discharge means 5 when is not connected increases.

  Next, a series of liquid ejection operations when the commercial power supply 21 is not supplied will be described with reference to FIGS.

  First, in FIG. 3, in the backup state (state where commercial power is not supplied), it is continuously determined in step s1 whether or not the lock release switch 8a is pressed. When it is detected that the lock release switch 8a has been pressed, the state of the hot water switch 4a at that time is determined based on the potential of the port of the microcomputer 6a connected to the hot water switch 4a (step s2).

  If this potential is "H", the hot water switch 4a is in an on state. Therefore, if the transistor 4b is turned on, it is dangerous because immediate discharge is performed, and the input of the lock release switch 8a is invalidated. When this potential is “L”, the lock release switch 8a is received and the transistor 4b is turned on (step s4).

  At this time, the liquid amount is detected by the water amount detecting means 12 (step s5), the voltage is switched by the discharge voltage switching means 13 based on the detected liquid amount (step s6), and the voltage is boosted by the boosting means 10. The voltage of the power source 9 is boosted (step s7), and power is supplied to the motor drive line. When the hot water switch 4a is pressed in this state, the transistor 4b is also turned on, so that the hot water operation is performed.

  Here, for example, when the amount of liquid detected by the water amount detecting means 12 is level 3, the voltage is switched to 6.4 V by the discharge voltage switching means 13 from FIG. The voltage is boosted to a voltage. Then, as a result, as shown in FIG. 4B, when the discharge is continuously performed, it is possible to discharge 4400 ml of liquid when the backup power source 9 is charged to the maximum.

  Returning to FIG. 3, the time since the last hot water switch 4a was pressed is counted, and it is determined whether or not the counted time is within 10 seconds (step s10). The port of the microcomputer 6a connected to 4b and the third transistor 10a is changed from "H" to "L", and the first transistor 4b and the third transistor 10a are turned off to return to the locked state (step s11).

  By the above operation, the discharge amount per unit time is changed according to the liquid amount in the container 1 by switching the discharge voltage applied to the discharge means 5 at the time of backup according to the liquid amount detected by the water amount detection means 12. The total discharge amount can be increased.

  In this embodiment, the capacity of the backup power supply 9 is preferably about 50 F. However, the present invention is not limited to this, and depends on the capacity of the container 1, the driving voltage of the motor 5c, the maximum voltage charged in the backup power supply 9, and the like. It is desirable to optimize the capacity of the backup power source 9 together.

  Needless to say, the display device 15 displays the applied voltage switched by the discharge voltage switching means 13 to improve the usability for the user.

  Further, although the backup power source 9 is the electric double layer capacitor 9a, it is not limited thereto, and may be a rechargeable battery such as a secondary battery.

  Further, in the present embodiment, the liquid level detected by the water amount detecting means 12 is set in four stages. However, this is not particular, and the more the subdivided, the more optimal the amount of hot water discharged per unit time. The total amount can be maximized.

  Further, the backup power supply detection means detects the voltage of the backup power supply 9 when the lock release switch 8a is pressed in the backup state, and the backup power supply and water quantity detection means 12 stored in the backup power supply 9 detects the voltage. By switching the discharge voltage in accordance with both the amount of liquid and the amount of liquid discharged, it is possible to optimize the amount of hot water discharged per unit time and further maximize the total discharge amount.

(Embodiment 2)
Next, an electric water heater according to the second embodiment of the present invention will be described with reference to FIGS. 1, 2, 5, and 6. FIG. Since the overall configuration of the electric water heater is the same as that of Embodiment 1, the description thereof is omitted.

  In FIG. 5, in the backup state (state where commercial power is not supplied), it is continuously determined in step s1 whether or not the lock release switch 8a is pressed. When it is detected that the lock release switch 8a has been pressed, the state of the hot water switch 4a at that time is then determined based on the potential of the port of the microcomputer 6a connected to the hot water switch 4a (step s2).

  If this potential is "H", the hot water switch 4a is in an on state. Therefore, if the transistor 4b is turned on, it is dangerous because immediate discharge is performed, and the input of the lock release switch 8a is invalidated. When this potential is “L”, the lock release switch 8a is received and the transistor 4b is turned on (step s4).

  At this time, the liquid amount is detected by the water amount detecting means 12 (step s5), the voltage is switched by the discharge voltage switching means 13 based on the detected liquid amount (step s6), and the voltage is boosted by the boosting means 10. The voltage of the power source 9 is boosted to the starting voltage (step s7), and the power is supplied to the motor drive line. When the hot water switch 4a is pressed in this state, the transistor 4b is also turned on, so that the hot water operation is performed. When the hot water switch 4a continues to be pressed for 0.3 seconds or longer (step s8), the discharge voltage switching means 13 switches to a steady voltage (step s9). Thus, by applying a high voltage at the start of discharge, the subsequent discharge amount is stabilized.

  Here, referring to FIG. 6, for example, in the case of the liquid level 2 detected by the water detection unit 12, the voltage is switched to 7.4 V by the discharge voltage switching unit 13 at the start-up by the boosting unit 10. The voltage is boosted to reach that voltage, and the voltage is switched to 6.6 V in the steady state.

  Then, returning to FIG. 5, the time since the last tapping switch 4 a was pressed is counted, and it is determined whether or not the counted time is within 10 seconds (step s 10). The port of the microcomputer 6a connected to 4b and the third transistor 10a is changed from "H" to "L", and the first transistor 4b and the third transistor 10a are turned off to return to the locked state (step s11).

  By the above operation, the starting voltage and the steady voltage are provided for the discharge voltage, and the starting voltage and the steady voltage among the discharge voltages applied to the discharging means 5 at the time of backup according to the liquid amount detected by the water amount detecting means 12. By switching both, the discharge amount per unit time can be optimized according to the liquid amount in the container 1, and the total discharge amount can be increased more stably.

  In this embodiment, the time for applying the starting voltage is set to 0.3 seconds. However, the present invention is not limited to this.

(Embodiment 3)
Next, the electric water heater in Embodiment 3 of this invention is demonstrated, referring FIGS. 7-9. Since the overall configuration of the electric water heater is the same as that of the first embodiment, the description thereof will be omitted, and the description will focus on the differences.

  As shown in FIG. 7, a time measuring unit 16 is provided for measuring the time after the temperature detecting unit 3 detects the boiling of the liquid in the container 1. Others are the same as in the first embodiment.

  In FIG. 8, in the backup state (state where commercial power is not supplied), it is continuously determined in step s1 whether or not the lock release switch 8a is pressed. When it is detected that the lock release switch 8a has been pressed, the state of the hot water switch 4a at that time is then determined based on the potential of the port of the microcomputer 6a connected to the hot water switch 4a (step s2).

  If this potential is "H", the hot water switch 4a is in an on state. Therefore, if the transistor 4b is turned on, it is dangerous because immediate discharge is performed, and the input of the lock release switch 8a is invalidated. When this potential is “L”, the lock release switch 8a is received and the transistor 4b is turned on (step s4).

  At this time, the amount of water is detected by the water amount detecting means 12 (step s5), and the elapsed time from the boiling time measured by the time measuring means 16 is detected (step s12). After switching the voltage by the discharge voltage switching means 13 based on the elapsed time (step s6), the voltage of the backup power source 9 is boosted to the starting voltage by the boosting means 10 (step s7), and the power is supplied to the motor drive line. To do. When the hot water switch 4a is pushed in this state, the first transistor 4b is also turned on, so that the hot water operation is performed. When the hot water switch 4a continues to be pressed for 0.3 seconds or longer (step s8), the discharge voltage switching means 13 switches to a steady voltage (step s9). Thus, by applying a high voltage at the start of discharge, the subsequent discharge amount is stabilized.

  Here, referring to FIG. 6, for example, when the elapsed time measured by the time measuring unit 16 at the liquid level 2 detected by the water amount detecting unit 12 is 20 to 40 minutes, The discharge voltage switching means 13 switches the voltage to 7.4V, and the boosting means 10 boosts the voltage so that the voltage becomes the same, and the voltage is switched to 6.6V in the steady state.

  Then, returning to FIG. 8, the time since the last tapping switch 4a was pressed is counted, and it is determined whether or not the counted time is within 10 seconds (step s10). The port of the microcomputer 6a connected to 4b and the third transistor 10a is changed from "H" to "L", and the first transistor 4b and the third transistor 10a are turned off to return to the locked state (step s11).

  By the above operation, the discharge voltage applied to the discharge means 5 at the time of backup is started according to both the elapsed time from the boiling time measured by the time measurement means 16 and the liquid amount detected by the water amount detection means 12. By switching both the voltage and the steady voltage, the discharge volume per unit time is reduced to the liquid volume in the container while avoiding the decrease in discharge volume due to the entrapment of bubbles accumulated in the pump, which is often seen immediately after boiling. Accordingly, the total discharge amount can be increased more stably.

  In this embodiment, the time measured by the time measuring means 16 is the elapsed time after the boiling is detected. However, for example, even after the commercial power supply 21 is turned off and the heating and warming operation is stopped. In addition to providing the above-mentioned effect, two time measuring means are provided, and both the elapsed time since the detection of boiling and the elapsed time after turning off the commercial power supply are used, so that the total discharge amount can be stabilized more stably. Can be more.

  Further, the same effect can be obtained by changing the discharge voltage in accordance with the temperature detected by the temperature detecting means 3 when the lock release switch 8a is received in the backup state, instead of the elapsed time after detecting the boiling. Is obtained. That is, the temperature is high after boiling, and as the time elapses, the temperature is lowered to the temperature to be kept warm, so that the elapsed time can be substituted by temperature detection.

  The configuration of each of the above first to third embodiments can be appropriately combined as necessary, and is not limited to the configuration of the embodiment itself.

  As described above, the electric water heater according to the present invention can efficiently discharge as much liquid as possible even after a long time has passed since the commercial power supply is turned off. It can also be applied to other liquid hot water storage devices.

The block diagram which shows the electric water heater in Embodiment 1, 2 of this invention Circuit diagram of the electric water heater Flow chart showing the operation of the electric water heater (A) The figure which shows the relationship between the water amount level and discharge voltage in the electric water heater (b) The graph which shows the relationship between the discharge voltage and discharge total amount The flowchart which shows operation | movement of the electric water heater in Embodiment 2 of this invention. The figure which shows the relationship between the water amount level and the discharge voltage in the electric water heater The block diagram which shows the electric water heater in Embodiment 3 of this invention Flow chart showing the operation of the electric water heater The figure which shows the relationship between the elapsed time after boiling detection and the discharge voltage in the electric water heater

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container 2 Heating means 3 Temperature detection means 4 Discharge control means 5 Discharge means 6 Control means 7 Heating control means 8 Lock release means 9 Backup power supply 10 Boosting means 11 Charging means 12 Water quantity detection means 13 Discharge voltage switching means 15 Display means 16 Timekeeping Means 21 Commercial power supply

Claims (8)

A container for storing a liquid; a discharge means for discharging the liquid in the container; a control means for controlling the discharge means; a backup power supply for supplying power when commercial power is not supplied; and a liquid in the container Water amount detecting means for detecting the amount of water and a discharge voltage switching means for switching the voltage applied to the discharge means, and when the commercial power is not supplied, the liquid amount detected by the water amount detection means Accordingly, an electric water heater configured to switch the voltage applied to the discharge means. Switching of the voltage applied to the discharge means when the commercial power is not supplied is performed according to both the amount of liquid detected by the water amount detection means and the power of the backup power stored in the backup power. The electric water heater according to claim 1. The voltage applied to the discharge means is composed of two stages, a start voltage at the start of discharge and a steady voltage at the time of stable discharge, and the discharge voltage switching means switches between both the start voltage and the steady voltage. The electric water heater according to 1 or 2. Switching of the voltage applied to the discharge means when the commercial power is not supplied is based on both the amount of liquid detected by the water amount detection means and the elapsed time after detecting that the liquid in the container has boiled. The electric water heater according to any one of claims 1 to 3, wherein the electric water heater is performed accordingly. Switching of the voltage applied to the discharge means when the commercial power is not supplied is performed according to both the amount of liquid detected by the water amount detection means and the time after the supply of the commercial power is stopped. The electric water heater according to any one of claims 1 to 4. The switching of the voltage applied to the discharge means when the commercial power is not supplied is performed according to both the liquid amount detected by the water amount detection means and the temperature of the liquid in the container. The electric water heater according to any one of 5. The electric water heater according to any one of claims 1 to 6, wherein the electric water heater has a display means, and the display means displays a voltage level applied to the discharge means when commercial power is not supplied. The electric water heater according to any one of claims 1 to 7, wherein switching by the discharge voltage switching means when commercial power is not supplied can be selected.