JPH11244145A - Electric water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep warmness of water for energy saving by calculating warm- keeping temp. for controlling warm keeping so as to reach a re-boiling state after a set heating time from a warm-keeping state when water inside an inner container is heated by an electric heater and re-boiled from the warm-keeping state after boiling. SOLUTION: When energy saving warm keeping is judged by the ON- operation of warm-keeping key after boiling is ended, the heating time (t) being the time required from the warm-keeping state to the end of re-boiling is set in a microcomputer control part 42. Then, energy saving warm-keeping temp. Th2 being temp. for boiling a quantity W of water after the heating time (t) is decided by the detecting signals of a water quantity sensor 17 and a room temp. sensor 19, etc. Then, hot water temp. Tw is compared with energy saving warm-keeping temp. Th2 , electricity conduction to a boiling heater 8a is stopped at the time of Tw>Th2 and electricity conduction to a warm-keeping heater 8b is started at the time of Tw<Th2 . Warm keeping is executed for energy saving by this conduction control method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric water heater, and more particularly, to an electric water heater capable of keeping a low-temperature heat at a temperature lower than a normal heat-retaining temperature (hereinafter referred to as energy-saving heat). .

[0002]

2. Description of the Related Art A well-known electric water heater uses an electric heater to heat water contained in a container body to boil and keep the temperature.

[0003] In recent years, public opinion regarding prevention of global warming has been increasing, and in order to reduce power consumption as much as possible, it has been required to save energy in electrical products.

[0004] Therefore, in the above-mentioned electric water heater, there has been developed an electric water heater in which the heat retaining temperature is lowered to save energy.
The temperature is set to 60 ° C. or 80 ° C., which is lower than the heat retention, to suppress power consumption.

[0005]

However, as described above, when the heat retention temperature is set low and the amount of hot water in the electric water heater is almost full, it takes too much time before re-boiling. In addition, the power consumption is not saved, and the user does not know the time until the hot water is boiled, which is inconvenient. Conversely, when the amount of hot water in the electric water heater is small, even if the temperature is kept at a lower temperature, there is no inconvenience because the time required for reboiling is short.

[0006] The present invention has been made in view of the above-mentioned point, and when reboiling is performed, reboiling is performed in a predetermined period of time, thereby conserving energy and improving boiling of hot water. It is intended to make the time until the time set by the user a predetermined time.

[0007]

In the basic structure of the present invention (the invention of claim 1), as a means for solving the above-mentioned problems, water contained in an inner container is heated by an electric heater and boiled. In the electric water heater which keeps the temperature at a predetermined temperature after the heating, when the water is reboiled from the temperature after the boiling, the heating time until the reboil is set to a predetermined time in advance. Heating time setting means, and a heat retention temperature calculating means for calculating a heat retention temperature for controlling the heat retention so as to reach a re-boiling state when the heating time preset by the heating time setting means elapses from the heat retention state. I have.

[0008] With the above-mentioned structure, when the heating time until the re-boiling is set to a predetermined time before the re-boiling from the heat retention state after the boiling,
A heat retention temperature for performing heat retention control is calculated so that a re-boiling state is reached when the preset heating time has elapsed. Therefore, the optimal heat retention temperature according to the amount of water is determined so that the hot water can be reboiled for a preset heating time, and the heat retention with energy saving becomes possible.
The time until the hot water is boiled can be set to a time predetermined by the user.

If the heating time setting means selects and sets a plurality of heating times, the heating time can be set as desired by the user.

In the case where the correction means for correcting the heat retention temperature by the heat retention temperature calculating means in accordance with the room temperature is provided as in the invention of claim 3, the room temperature changes (for example, the room temperature greatly varies depending on the season). Is corrected, and the heat retention temperature calculated in accordance with (i) is corrected, so that further energy saving can be achieved.

According to a fourth aspect of the present invention, in the case where display control means for displaying the heating time set by the heating time setting means on an electronic display unit for displaying the amount of water is provided, the heating time until re-boiling is reduced by the amount of water. The information is displayed on the display electronic display unit, and the user can confirm the heating time until re-boiling by the electronic display unit for water amount display.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First Embodiment (Corresponding to Claims 1 to 5) FIGS. 1 to 6 show an electric water heater according to a first embodiment of the present invention.

As shown in FIGS. 1 and 2, this electric water heater has a container body 1 configured to be capable of storing water.
And an openable and closable lid 2 for covering the upper opening of the container body 1.

The container body 1 includes an inner container 3 made of metal (for example, stainless steel) forming an inner peripheral surface, an outer case 4 made of synthetic resin (for example, polypropylene) forming an outer peripheral surface, Synthetic resin (for example, polypropylene) that joins the upper edge of the inner container 3 and the upper edge of the outer case 4
, And a bottom plate 6 made of synthetic resin (for example, made of polypropylene) that covers the lower end opening of the outer case 4. A space 7 is formed. That is, the outer case 4 and the bottom plate 6 are members constituting the outer wall of the container body 1.

The lid 2 is detachably attached to a hinge receiver 13 formed on the rear side of the shoulder member 5 via a hinge pin 14 which is detachable.

On the lower surface of the bottom of the inner container 3, the inner container 3
An electric heater 8 for heating water stored in the inside is provided. The electric heater 8 includes a boiling heater 8a and a warming heater 8b as described later (FIG. 4).
reference). Reference numeral 9 denotes a temperature sensor for detecting the temperature of water (or hot water) contained in the inner container 3 (specifically, the temperature of the inner container 3), and 10 denotes the heat of the electric heater 8 radiated downward. This is a heat shield plate for preventing the occurrence of heat.

At the bottom of the inner container 3, a liquid discharging passage 11 for discharging hot water in the inner container 3 to the outside is connected. A space 7 formed on the front side (that is, the side opposite to the hinge pin) between the outer case 4 and the outer case 4 extends upward, and a spout 1 at the tip thereof.
2 faces a pipe cover 4a formed on the upper part of the outer case 4. Reference numeral 15 denotes the liquid discharge passage 11
This is a water stop valve provided at the upper end of the water tank.

An electric pump 16 for discharging liquid is interposed in a lower portion of the liquid discharging passage 11 (that is, a portion located in the space 7 formed between the bottom of the inner container 3 and the bottom plate 6). (See FIG. 2).

As shown in FIG. 2, the upward straight pipe portion 11a of the liquid discharge passage 11 is
And a capacitance-type electronic water flow sensor 17 is provided in the straight pipe portion 11a. The outer case 4 is provided with an electronic display 18 for displaying the amount of water detected by the water amount sensor 17 at a position slightly closer to the side than immediately below the spout 12.

As shown in FIGS. 5 and 6, the electronic display unit 18 has six display windows 18A to 18F illuminated by display lamps (not shown), and these display lamps 18A to 18F are provided. Is displayed, six levels from the amount of water required to be supplied to the full level are displayed.

As will be described later, the electronic display unit 18 sets the energy-saving warming time ts set by the saving timer key 30 (see FIG. 3) to 6 by blinking these indicator lights 18A to 18F. The time t required for re-boiling after the energy saving and heat keeping set by the energy saving and heat keeping key 32 (see FIG. 3) is displayed in three stages (that is, 5 minutes, 10 minutes, and 15 minutes). Minutes). Here, the energy-saving heat retention is a heat retention (that is, a low-temperature heat retention) at a temperature lower than a normal heat retention temperature (for example, 98 ° C.), and an energy-saving effect can be expected by performing the low-temperature heat retention. Reference numeral 19 denotes a room temperature sensor provided on the bottom plate 6 of the container body 1.

In FIGS. 1 and 2, reference numeral 20 denotes a rotary seat, 21 denotes a steam discharge passage formed in the lid 2, 22 denotes a water stop valve provided in the steam discharge passage 21, and 23 denotes a lid 2
, A lock mechanism for holding a closed state, a carrying handle 24, a microcomputer board 25, and a microcomputer board housing section for housing the microcomputer board 25.

On the front side of the shoulder member 5, there is provided an operation panel 27 on which operation parts of various switches and various indicators are arranged.

As shown in FIG. 3, the operation panel 27 has a hot water supply key 28, a lock key 29, a saving timer key 30, a boiling / descaling key 31, a heat keeping key 32, a lock release indicator light 33, and a saving timer display. Light 34, boiling indicator light 35, descaling indicator light 36, normal warming indicator light 37,
An energy-saving warming indicator light 38 is provided. According to the number of ON operations of the saving timer key 30, six steps (that is, 1
６6 hours) can be set, and the time until re-boiling can be set in three stages (ie, 5 minutes, 10 minutes, 15 minutes) by the number of ON operations of the heat retention key 32. The set times are displayed by blinking the display windows 18A to 18F of the electronic display unit 18 as described above.

Each electric element in the electric water heater is connected as shown in FIG. In FIG. 4, reference numeral 39 denotes an AC power supply, 40 denotes a triac for the heat retaining heater 8b, 41 denotes a power supply circuit, and 42 denotes a microcomputer control unit. The same reference numerals are given to the already described electrical elements, and the description thereof will be omitted.

The microcomputer control unit 42 includes temperature information from the temperature sensor 9 and the room temperature sensor 19, water amount information from the water amount sensor 17, an ON operation signal of the saving timer key 30, an ON operation signal of the heat keeping key 32, a boiling / calcium Various calculation processes are performed based on the ON operation signal of the key 31 and the results are used as control signals as a heater 8a for boiling, a heater 8b for keeping heat, the electronic display unit 18, and various display lamps 33 to 38.
Output to

That is, the microcomputer control unit 25 functions as a heating time setting means for setting the heating time t until the re-boiling to a predetermined time before the re-boiling from the heat retention state after the boiling. And a heat-retaining temperature Th for controlling the heat retention so as to reach a re-boiling state when a heating time t preset by the heating time setting means has elapsed from the heat-retaining state.
And functions as a heat insulation temperature calculating means for calculating a _2, and functions as a correction means for correcting the retained temperature Th ₂ by-holding temperature temperature calculation means so as to correspond to the room temperature Tr, the heating time set by the heating time setting means It has a function as a display control means for displaying t by the electronic display unit 18 for displaying the water amount.

Next, the heat retention control and the reboil control in the electric water heater configured as described above will be described in detail with reference to flowcharts shown in FIGS.

[0030] (I) incubated control the boiling in step S ₁ (flowchart see FIG. 7) is determined to have ended,
Whether energy saving insulation determination is made in step S _2. This determination is made based on the presence or absence of the ON operation of the heat retention key 32. Here, if a negative determination is made, step S
Advances to _3, detecting water temperature Tw is input from the temperature sensor 9, the normal temperature retaining control is performed in step S ₄ ~ Step S _7.

In the normal heat retention control, the hot water temperature Tw is maintained at a normal heat retention temperature Th ₁ (for example, 98 ° C.). That is, made a comparison of the hot water temperature Tw and usually retained temperature Th ₁ in step S ₄ and step S _6, if it is determined that Tw ≧ Th ₁ in step S _4, the in step S ₅ to the hot water boiling heater 8a Power supply is stopped,
If it is determined that Tw <Th ₁ in step S _6, the energization of the thermal insulation heater 8b is started in step S _7,
And then returns to step S _2.

The affirmative determination in step S ₂ (i.e., energy saving insulation and determination) if has been, set the heating time t is performed in step S _8. The heating time t is a time required from the heat retention state to the end of re-boiling. The setting is made by the heating time setting means based on the number of ON operations of the heat retention key 32. For example, t = 5 minutes for one ON operation, t = 10 minutes for two ON operations, and t = 15 minutes for three ON operations.

[0033] Then, the detection amount of water W from the water sensor 17 in step S _9, the detection water temperature Tw from the temperature sensor 9 is inputted detection temperature Tr from the room temperature sensor 19, in step S ₁₀ of energy saving insulation temperature Th ₂ A decision is made. The energy saving heat retention temperature Th ₂ is a temperature at which the water of the water amount W will reach boiling if the heating time t is applied, and fluctuates when the water amount W and the heating time t change. Is corrected according to the room temperature Tr. That is, when the room temperature Tr is high, the energy saving heat-retaining temperature Th ₂ is a value corrected to be lower, and when the room temperature Tr is low, the energy saving heat-retaining temperature Th ₂ is corrected to be higher. The correction is performed by a correction unit. Then, step S ₁₁
In step S <b> ₁₄ , energy-saving heat retention control is performed.

The energy saving heat control is to maintain the hot water temperature Tw at the energy saving heat temperature Th ₂ . That is, the hot water temperature Tw in a step S ₁₁ and step S ₁₃
Is compared with the energy-saving warming temperature Th _2, and step S
If it is determined that Tw ≧ Th ₂ at _11, the step S ₁₂
In the stopped energization to the hot water boiling heater 8a, when it is determined that Tw <Th ₂ in step S _13, the energization of the thermal insulation heater 8b is started in step S _14.

(II) Re-boiling control (Refer to the flowchart of FIG. 8) If it is determined in step S ₁ that energy saving and heat keeping is to be performed, and if it is determined in step S ₂ that the boiling and descaling key 31 has been turned ON, in step S ₃ setting the heating time t is read out, set the heating time in step S ₄ t
There is displayed on the electronic display unit 18, energization of the hot water boiling heater 8a is started further in step S _5. The display of the heating time is performed by the display windows 18A to 1A of the electronic display window 18.
This is performed by blinking 8F.

[0036] Then, the heating time in step S ₆ t
When There is judged to have elapsed, the stopped energization to the hot water boiling heater 8a in step S _7, as well as shifts in the energy-saving heat retention at energy saving retained temperature Th ₂ again, the heating time display stops at the electronic display unit 18 Is done.

The temporal change of the hot water temperature Tw in the above-mentioned heat retention control and re-boiling control is as shown in the time chart of FIG.

As described above, in the present embodiment, when the reheating is performed from the heat retention state after the boiling, the heating time t up to the reboiling is set to a predetermined time in advance. A heat retention temperature T for controlling the heat retention so as to reach a re-boiling state when the preset heating time t has elapsed.
h ₂ is calculated. Therefore, the preset heating time t
In order to perform the re-boiling of the hot water, the optimum heat retaining temperature Th ₂ according to the amount of water is determined, so that the heat can be kept with energy saving and the time until the hot water is boiled by the user is determined in advance. It can be.

Since a plurality of heating times t can be selected and set, the heating time can be set as desired by the user.

Further, the energy saving heat-retaining temperature Th _{2 is changed} to the room temperature T.
r, the energy-saving heat-retaining temperature Th in the heat-retention control corresponding to the change of the room temperature Tr (for example, the room temperature greatly changes depending on the season).
₂ is corrected, and further energy saving can be achieved.

Also, since the heating time t is displayed on the electronic display unit 18 for displaying the amount of water, the heating time t until re-boiling is displayed on the electronic display unit 18 for displaying the amount of water. The user can confirm the heating time t until re-boiling by the electronic display unit for display.

Second Embodiment (Corresponding to Claims 1 to 4) FIG. 10 shows a flowchart of heat retention / reboil control in an electric water heater according to a second embodiment of the present invention. I have.

In this case, the mechanical structure and the electric structure of the electric water heater are the same as those in the first embodiment.

In this embodiment, the energy-saving heat-retention time can be set by turning on the economy timer key 34.

Next, a description will be given of the heat retention and reboil control in the electric water heater according to the present embodiment with reference to the flowchart of FIG.

[0046] confirmed the boiling in step S ₁ is completed, usually kept (for example, in step S _2, 98
℃ heat retention at) is initiated by ON operation count savings timer key 34 in step S ₃ in the normal during incubation, save timer (i.e., energy saving incubation time) ts is set. The saving timer ts is set to one hour for each ON operation of the saving timer key 34, and is set in six stages (that is, 1 to 6 hours).

[0047] When the setting of the save timer ts is made, the remaining time on the electronic display unit 18 (in this case, the set time) in step S ₄ is displayed. This remaining time display
As shown in FIG. 6, a display window 18 of the electronic display unit 18 is provided.
This is performed by blinking any one of A to 18F. Said residue time display is performed up to 10 seconds at step S ₅ is confirmed to have elapsed, remaining time displayed in step S ₆ after lapse of 10 seconds is stopped.

[0048] Then, the heating time in step S ₇ t
Is set. The heating time t is a time required from the heat retention state to the end of re-boiling. The settings are:
This is performed by the heating time setting means based on the number of ON operations of the heat retention key 32. For example, t = 5 by one ON operation
Min, t = 10 min with 2 ON operations, t = 3 min with 3 ON operations
= 15 minutes.

[0049] Then, the detection amount of water W from the water sensor 17 in step S _8, the detection water temperature Tw from the temperature sensor 9, the detection temperature Tr from the room temperature sensor 19 are input, in step S ₉ energy saving retained temperature Th ₂ A decision is made. The energy saving heat retention temperature Th ₂ is a temperature at which the water of the water amount W will reach boiling if the heating time t is applied, and fluctuates when the water amount W and the heating time t change. Is corrected according to the room temperature Tr. That is, when the room temperature Tr is high, the energy saving heat-retaining temperature Th ₂ is a value corrected to be lower, and when the room temperature Tr is low, the energy saving heat-retaining temperature Th ₂ is corrected to be higher. The correction is performed by a correction unit.

[0050] saving timer ts in step S ₁₀
It is determined whether or not has elapsed. Here, if a negative determination (i.e., if it is determined to be in energy saving insulation), the process proceeds to step S _11, where the boiling-without chlorine key 31 is determined not to be turned ON , energy saving heat keeping control is performed in step S ₁₂ ~ step S _14.

In the energy-saving heat keeping control, the hot water temperature Tw is kept at the energy-saving heat keeping temperature Th ₂ . That is, the hot water temperature Tw in a step S ₁₂ and step S ₁₄
Is compared with the energy-saving warming temperature Th _2, and step S
_If it is determined in Step ₁₂ that Tw ≧ Th ₂ , Step S ₁₃
In the stopped energization to the hot water boiling heater 8a, when it is determined that Tw <Th ₂ in step S _14, the energization of the thermal insulation heater 8b is started in step S _15.

[0052] By the way, there is a case where in the middle of saving timer ts has elapsed want to know the remaining time is in how much is, in that case, saving timer key 34 is turned ON in step S _16, step remaining time at that time in S ₁₇ is an electronic display window in the same manner as described above 1
8 is displayed. Said residue time display is performed up to 10 seconds at step S ₁₈ is confirmed to have elapsed in step S ₁₉ after lapse of 10 seconds remaining time display is stopped, then control returns to step S _8.

[0053] On the other hand, if the determination is positive at step S ₁₁ (i.e., if the boiling-without chlorine key 31 is turned ON), the process proceeds to step S _20, the set set heating time in step S ₇ t is read out, set the heating time t in step S ₂₁ is displayed on the electronic display unit 18, further water boiling heater 8a in step S ₂₂
The energization to is started. The display of the heating time is performed by blinking the display windows 18A to 18F in the electronic display window 18.

[0054] Then, the heating time in step S ₂₃ t
There it is determined that the elapsed, in step S ₂₄ is energized stopped to water boiling heater 8a, is then continued energy saving insulation is, the heating time display on the electronic display unit 18 is stopped in step S _25.

[0055] Further, in the case where a negative determination is made in step S ₁₀ (i.e., if the energy saving insulation by saving timer is determined to have finished), the process proceeds to step S _26, the start current is supplied to the hot water boiling heater 8a are, hot water Tw is boiling temperature Th ₀ in step S ₂₇ (i.e., 100 ° C.) when determined as the above, power supply to the hot water boiling heater 8a is stopped in step S _28.

Hot water temperature T in the above-mentioned heat retention / reboil control.
The temporal change of w is as shown in the time chart of FIG.

According to the above-described heat retention / reboil control, energy saving and heat retention can be performed while the saving timer ts has elapsed, so that power consumption can be saved and the remaining time can be displayed, which is convenient for the user. In addition, since the re-boiling is completed after the elapse of the saving timer ts, the usability is improved. Other functions and effects are the same as those in the first embodiment, and a description thereof will be omitted.

Third Embodiment (Corresponding to Claims 1, 2, and 4) FIGS. 12 and 13 show heat retention control and reboil control in an electric water heater according to a third embodiment of the present invention. Is shown.

In this case, the mechanical structure and the electric structure are the same as those of the first embodiment except that the output of the heater 8a is variable.
This is the same as in the embodiment.

In the present embodiment, the heat retention temperature Th ₂ at the time of energy conservation heat retention is set to a constant value (for example, 75 ° C.), and the heater 8 for re-boiling at the time of re-boiling according to the water amount W and the room temperature Tr.
By changing the output of “a”, re-boiling is completed in the set heating time t.

Next, a description will be given of the heat retention control and the reboil control in the electric water heater according to the present embodiment with reference to the flowcharts of FIGS.

[0062] (I) incubated control the boiling in step S ₁ (flowchart see Figure 12) is determined to have ended,
Whether energy saving insulation determination is made in step S _2. This determination is made based on the presence or absence of the ON operation of the heat retention key 32. Here, if a negative determination is made, step S
Advances to _3, the detected coolant temperature Tw input from the temperature sensor 9, the normal temperature retaining control is performed in step S ₄ ~ Step S _7.

In the normal heat retention control, the hot water temperature Tw is maintained at a normal heat retention temperature Th ₁ (for example, 98 ° C.). That is, made a comparison of the hot water temperature Tw and usually retained temperature Th ₁ in step S ₄ and step S _6, if it is determined that Tw ≧ Th ₁ in step S _4, the in step S ₅ to the hot water boiling heater 8a Power supply is stopped,
If it is determined that Tw <Th ₁ in step S _6, the energization of the thermal insulation heater 8b is started in step S _7,
And then returns to step S _2.

If an affirmative determination is made in step S ₂ (that is, it is determined to be energy saving and heat keeping), a heating time t is set in step S ₈ . The heating time t is a time required from the heat retention state to the end of re-boiling. The setting is made by the heating time setting means based on the number of ON operations of the heat retention key 32. For example, t = 5 minutes for one ON operation, t = 10 minutes for two ON operations, and t = 15 minutes for three ON operations.

[0065] Then, the detection amount of water W from the water sensor 17 in step S _9, the detection water temperature Tw from the temperature sensor 9, the detection temperature Tr from the room temperature sensor 19 is inputted, the hot water boiling heater 8a in step S ₁₀ The output H is determined. The output H is an output from which the heating power required for the water of the water amount W to reach the energy-saving warming temperature Th ₂ (for example, 75 ° C.) at the heating time t to the boiling point is obtained, and the water amount W and the heating time t change. However, the output estimated from the amount of water W is corrected according to the room temperature Tr. That is, when the room temperature Tr is high, the output H has a slightly corrected value, and when the room temperature Tr is low, the output H is corrected to be relatively large. The correction is performed by a correction unit.

In step S ₁₁ to step S ₁₄ , the energy-saving heat control is executed. In the energy-saving heat control, the hot water temperature Tw is changed to the energy-saving heat temperature Th ₂ (for example, 7).
5 ° C.). That is, step S
₁₁ and Comparison with hot water temperature Tw and energy retained temperature Th ₂ in step S ₁₃ is performed, Tw in a step S ₁₁
When it is determined that ≧ Th ₂ , the power supply to the water heater 8 a is stopped in step S ₁₂ , and when it is determined that Tw <Th ₂ in step S ₁₃ , the power supply to the heat retaining heater 8 b is performed in step S ₁₄ . Be started.

(II) Re-boiling control (Refer to the flowchart in FIG. 13) If it is determined in step S ₁ that the energy saving and heat-retention is performed, and if it is determined in step S ₂ that the boiling and descaling key 31 has been turned ON, in step S ₃ setting read heating time t and the heater output H is, step S ₄ in the setting heating time t is displayed on the electronic display unit 18, further power output H of the step S ₅ to the hot water boiling heater 8a
Started with The display of the heating time is performed by blinking the display windows 18A to 18F in the electronic display window 18.

[0068] Then, the heating time in step S ₆ t
There it is determined that the elapsed, the energization of the hot water boiling heater 8a is stopped in step S _7, the heating time display on the electronic display unit 18 is blinking.

According to the above, energy-saving heat-retaining control at a constant energy-saving heat-retaining temperature Th (for example, 75 ° C.) is performed, and the output H of the water heater 8a is changed according to the heating time t. The time required for reboil can be determined. In other words, re-boiling can be performed at a time desired by the user while keeping the energy saving and the heat. Other functions and effects are the same as those in the first embodiment, and a description thereof will be omitted.

In each of the above embodiments, the heat retaining key 3
Although the energy-saving heat retention is started by the ON operation of No. 2, it may be shifted to the energy-saving heat retention when a predetermined time has elapsed after boiling.

[0071]

According to the invention of the present application (the invention of claim 1),
Heat the water contained in the inner container with an electric heater,
In an electric water heater that is kept at a predetermined heat retention temperature after boiling, when re-boiling from the heat retention state after boiling, a heating time until the re-boiling is set to a predetermined time in advance. Heating time setting means for performing heating and a heat retaining temperature calculating means for calculating a heat retaining temperature for controlling the heat retention so as to reach a re-boiling state when the heating time preset by the heating time setting means elapses from the heat retaining state. When the heating time up to the re-boiling is set to a predetermined time in advance when re-boiling from the warmed state after the boiling, the re-boiling is performed when the preset heating time has elapsed. Since the heat retention temperature for controlling the heat retention is calculated so as to reach the state, the optimal heat retention temperature according to the water amount will be determined so that the hot water can be reboiled for a preset heating time, Together becomes possible insulation in the energy, there is an effect that the time until water boils user can be made to be a predetermined time.

When the heating time setting means selects and sets a plurality of heating times, the heating time can be set as desired by the user.

In the case where the correction means for correcting the heat retention temperature by the heat retention temperature calculating means in accordance with the room temperature is provided, the room temperature changes (for example, the room temperature greatly varies depending on the season). In this case, the heat-retention temperature in the heat-retention control is corrected in accordance with the above-mentioned condition, and further energy saving can be achieved.

[0074] When the display control means for displaying the heating time set by the heating time setting means on an electronic display unit for displaying the amount of water is provided as in the invention of claim 4, the heating time until re-boiling is reduced by the amount of water. The information is displayed on the display electronic display unit, and the user can confirm the heating time until re-boiling by the electronic display unit for water amount display.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electric water heater according to a first embodiment of the present invention.

FIG. 2 is a front view showing a cross section of a part of the electric water heater according to the first embodiment of the present invention.

FIG. 3 is a plan view of an operation panel in the electric water heater according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a connection state of electric elements in the electric water heater according to the first embodiment of the present invention.

FIG. 5 is an enlarged front view of an electronic display unit in the electric water heater according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating a display state of an electronic display unit in the electric water heater according to the first embodiment of the present invention.

FIG. 7 is a flowchart for explaining heat retention control in the electric water heater according to the first embodiment of the present invention.

FIG. 8 is a flowchart for explaining boiling control in the electric water heater according to the first embodiment of the present invention.

FIG. 9 is a time chart showing a change in water temperature during heat retention / boiling control in the electric water heater according to the first embodiment of the present invention.

FIG. 10 is a flowchart for explaining heat retention / boiling control in the electric water heater according to the second embodiment of the present invention.

FIG. 11 is a time chart showing a change in water temperature during heat retention / boiling control in the electric water heater according to the second embodiment of the present invention.

FIG. 12 is a flowchart for explaining heat retention control in an electric water heater according to a third embodiment of the present invention.

FIG. 13 is a flowchart for explaining boiling control in the electric water heater according to the third embodiment of the present invention.

[Explanation of symbols]

3 is an inner container, 8 is an electric heater, 8a is a heater for boiling water, 8
b is a heater for keeping heat, 9 is a temperature sensor, 17 is a water amount sensor, 18 is an electronic display unit, 19 is a room temperature sensor, 31 is a boiling and descaling key, 32 is a heat keeping key, and 42 is a microcomputer control unit.

Claims (4)

[Claims] 1. An electric water heater in which water contained in an inner container is heated by an electric heater, boiled, and then kept at a predetermined temperature, and kept warm after boiling. When re-boiling, heating time setting means for setting the heating time up to the re-boiling to a predetermined time in advance, and when the heating time set by the heating time setting means from the heat retention state elapses An electric water heater further comprising a heat retaining temperature calculating means for calculating a heat retaining temperature for controlling the heat retention to reach a re-boiling state. 2. The electric water heater according to claim 1, wherein said heating time setting means selects and sets a plurality of heating times. 3. An electric water heater according to claim 1, further comprising correction means for correcting the heat retaining temperature by said heat retaining temperature calculating means in accordance with the room temperature. vessel. 4. The apparatus according to claim 1, further comprising display control means for displaying the heating time set by said heating time setting means on an electronic display unit for displaying the amount of water. An electric water heater according to the item.