JP3539503B2 - Electric water heater - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an electric water heater that stores hot water boiled by an electric heater in a hot water storage tank.
[0002]
[Prior art]
Some electric water heaters are of an external heating type. The externally heated electric water heater boils hot water in a heating pipe provided separately from the hot water storage tank. FIG. 6 shows an example of such an electric water heater. The electric water heater includes a hot water storage tank 1 for storing the hot water, a heating pipe 50 for boiling the hot water, an upper pipe 2 connecting the upper part of the hot water storage tank 1 and the upper part of the heating pipe 50, and a lower part of the hot water storage tank 1. And a lower tube (3) connecting the lower portion of the heating tube (50).
[0003]
As shown in FIG. 7, a wax valve 51 is provided as a temperature flow control valve at an upper outlet 50A of the heating tube 50, and a U-shaped electric heater 52 for boiling hot water is provided at a lower portion thereof.
[0004]
As shown in FIG. 8A, the wax valve 51 of the heating tube 50 includes a temperature detecting section 51B having a telescopic section 51A at the tip and a valve section 51D which is urged by a spring 51C and is in a fully closed state. . Then, when the temperature of the hot water detected by the temperature detecting section 51B reaches a predetermined temperature, as shown in FIG. 8B, the expansion and contraction section 51A extends due to the urging force of the spring 51C, and the valve section 51D is fully opened.
[0005]
In such an electric water heater, when the wax valve 51 is in the fully closed state, the electric heater 52 boil water in the heating tube 50. When the temperature of the hot water reaches a predetermined temperature, the wax valve 51 detects the temperature of the hot water and enters a fully open state. Thereby, the hot water in the heating pipe 50 moves to the hot water storage tank 1 by natural convection. That is, the hot water in the heating pipe 50 flows into the upper part of the hot water storage tank 1 through the upper pipe 2 as shown by the arrow A. Hot water storage tank 1 stores this hot water in the upper part. At the same time, the water in the lower part of the hot water storage tank 1 flows into the heating pipe 50 through the lower pipe 3 as shown by the arrow B. As a result, the temperature of the hot water in the heating tube 50 decreases, the wax valve 51 is fully closed, and the previous operation is repeated again.
[0006]
Thus, a layer of high-temperature water 101 at a predetermined temperature and a layer of low-temperature water 102 are formed in hot water storage tank 1, and the user uses high-temperature water 101.
[0007]
[Problems to be solved by the invention]
By the way, it has been found that an externally heated electric water heater using a temperature flow control valve such as a wax valve has the following problems.
[0008]
In this electric water heater, the wax valve 51 has a structure that opens when the detected temperature reaches a predetermined temperature, but there is a delay time from when the predetermined temperature is detected to when the valve opens.
[0009]
In the electric water heater that forms a layer of the high-temperature water 101 and a layer of the low-temperature water 102 in the hot-water storage tank 1, heat is transferred from the high-temperature water 101 to the low-temperature water 102. As a result, when the amount of the low-temperature water 102 in the hot water storage tank 1 decreases, the temperature of the low-temperature water 101 increases. When heating starts in the heating pipe 50 into which the low-temperature water 102 whose temperature has risen has flowed, as shown in FIG. 9, within a short time after the energization start time T1, that is, within a delay time of the wax valve 51, The temperature of the hot water may rise to 100 degrees or higher, and the hot water may be too hot.
[0010]
Thereafter, the wax valve 51 is opened, the hot water moves from the heating pipe 50 to the hot water storage tank 1 by natural convection, and the hot water also moves inside the heating pipe 50. Thus, at time T2, the temperature of the hot water in heating tube 50 decreases. Thereafter, the temperature of the wax valve 51 itself increases and the water in the heating tube 50 is boiled by convection, so that the boiling of the hot water does not occur too much. That is, when the hot water temperature rises after time T3, the wax valve 51 is opened, and when the hot water temperature falls after time T4, the wax valve 51 is repeatedly closed.
[0011]
As described above, when the hot water in the heating tube 50 boils, the temperature of the hot water is reduced to 100 degrees or less, which deviates from the provisions of the electric water heater. This causes problems such as inviting and shortening the service life.
[0012]
An object of the present invention is to provide an electric water heater that can prevent the boiling of hot water in a heating pipe from occurring at the start of energization, excluding such disadvantages.
[0013]
[Means for Solving the Problems]
In order to achieve the object, a first invention is a hot water storage tank for storing boiling water, a heating pipe having a temperature flow control valve at an upper outlet, which is opened when the boiling water reaches a predetermined temperature, In an electric water heater including a lower pipe connecting a lower part of a hot water storage tank and a lower part of a heating pipe, and an upper pipe connecting an outlet of the heating pipe and an upper part of the hot water storage tank, the electric water heater is provided in the heating pipe to boil water in the heating pipe. Power to one electric heater and the other electric heater to a non-conductive state only for a predetermined time from the start of energization, and to supply power to the two electric heaters after a predetermined time Control means for performing the operation.
[0014]
Further, the second invention provides a hot water storage tank for storing the hot water, a heating pipe having a temperature flow control valve at an upper outlet which opens when the hot water reaches a predetermined temperature, In an electric water heater comprising a lower pipe connecting the lower pipe and an upper pipe connecting an outlet of the heating pipe and an upper part of the hot water storage tank, an electric heater provided in the heating pipe and boiling hot water by supplying a predetermined electric power And control means for supplying power less than a predetermined power to the electric heater only for a predetermined time from the start of energization and supplying predetermined power to the electric heater after a predetermined time.
[0015]
[Action]
According to the first aspect, at the start of energization to the electric heater of the heating tube, the control unit supplies power to only one electric heater, so that boiling of the hot water in the heating tube at the start of energization is prevented.
[0016]
Further, according to the second aspect, at the start of energization of the electric heater of the heating tube, the control means supplies less electric power to the electric heater than the predetermined electric power, so that the boiling of the hot water of the heating tube generated at the start of energization is prevented. Is done.
[0017]
【Example】
Next, embodiments of the present invention will be described with reference to the drawings.
[0018]
[Example 1]
FIG. 1 is a schematic diagram showing Embodiment 1 of the present invention. The electric water heater according to the first embodiment includes a hot water storage tank 1, an upper pipe 2, a lower pipe 3, a heating pipe 10, and a control unit 20. Further, the control unit 20 includes a power supply unit 21, a control unit 22, and a switching unit 23.
[0019]
The hot water storage tank 1, the upper pipe 2, and the lower pipe 3 of this electric water heater are the same as the conventional electric water heater of FIG.
[0020]
As shown in FIG. 2, a wax valve 11 is provided as a temperature flow control valve at an outlet 10 </ b> A above the heating pipe 10. Further, two U-shaped electric heaters 12 and 13 are provided at a lower portion in the heating tube 10. The electric capacity of the electric heater 12 is substantially equal to the electric capacity of the electric heater 13, and the total electric capacity of the electric heater 12 and the electric heater 13 is equal to the capacity of one conventional electric heater. The electric wires 12A and 13A for supplying electric power to these electric heaters 12 and 13 are connected to the switching unit 23 of the control means 20, respectively.
[0021]
The power supply unit 21 of the control unit 20 supplies power to the electric heaters 12 and 13 to the switching unit 23.
[0022]
The control unit 22 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and controls the switching unit 23 based on settings for boiling hot water. What is set in the control unit 22 includes an energization start time, an energization time, an amount of boiling water, and the like.
[0023]
The switching unit 23 supplies the electric power from the power supply unit 21 to the electric heater 12, supplies the electric power to both the electric heaters 12 and 13, or controls the electric heaters 12 and 13 under the control of the control unit 22. 13 is turned off.
[0024]
Next, the operation of the first embodiment will be described.
[0025]
When it is time to start energizing the electric heaters 12 and 13, the control unit 22 starts energizing one of the electric heaters 12 as shown in FIG. 3 (step S1). Then, the power supply to the electric heater 12 is continued for N minutes (step S2). Here, N minutes is usually between 5 minutes and 10 minutes. When the energization for N minutes is completed in step S2, energization of both electric heaters 12 and 13 is started (step S3). Thereafter, the control unit checks the set amount of hot water, that is, whether or not the set amount of hot water has boiled (step S4), and turns off both electric heaters 12 and 13 when the set amount of hot water has boiled (step S5), The control for boiling hot water ends.
[0026]
In this way, when the power supply start time comes, the control unit 22 supplies power to one of the electric heaters 12 only for the first N minutes, so that the hot water in the heating pipe 10 generated at the start of power supply is generated. Excessive boiling can be prevented.
[0027]
Further, since the boiling of the hot water in the heating pipe 10 is prevented, the characteristic of the wax valve 11 can be prevented from being deteriorated, and the life can be extended.
[0028]
[Example 2]
FIG. 4 is a schematic diagram showing Embodiment 2 of the present invention. The electric water heater according to the second embodiment includes a hot water storage tank 1, an upper pipe 2, a lower pipe 3, a heating pipe 30, and a control means 40. The control means 40 includes a power supply unit 41, a control unit 42, and a power control unit 43.
[0029]
Since the hot water storage tank 1, the upper pipe 2, and the lower pipe 3 of the second embodiment are the same as those of the first embodiment, the description thereof will be omitted. In addition, the power supply unit 41 is the same as the power supply unit 21 of the first embodiment, and a description thereof will be omitted.
[0030]
The heating pipe 30 is provided with a wax valve 31 and, similarly to FIG. 7, one electric heater 32 is provided.
[0031]
The control unit 42 controls the power control unit 43 based on settings for boiling hot water and the like. The control unit 42 sets the power supply start time, power supply time, amount of boiling water, and the like.
[0032]
The power control unit 43 controls the power from the power supply unit 41 under the control of the control unit 42. That is, the power control unit 43 controls whether to supply less power than the rated power to the electric heater 32, supply the rated power to the electric heater 32, or turn off the electric heater 32.
[0033]
Next, the operation of the second embodiment will be described.
[0034]
When the energization start time comes, as shown in FIG. 5, the control unit 42 supplies less power than the rating to the electric heater 32 (step S11), and continues this state for N minutes (step S12). When step S12 ends, power of the rated capacity is supplied to the electric heater 32 (step S13). Thereafter, the control unit checks whether the set amount of hot water has boiled (step S14). When the set amount of hot water has boiled, the control unit turns off the electric heater 32 (step S15), and ends the control for boiling the hot water.
[0035]
In this way, when the power supply start time comes, the control unit 42 supplies less power than the rating to the electric heater 32 for the first N minutes. Can be prevented from boiling too much.
[0036]
【The invention's effect】
As described above, in the first invention, two electric heaters are provided in the heating pipe and power is supplied to only one electric heater at the start of energization, so that excessive boiling of hot water generated at the start of energization is prevented. it can.
[0037]
Further, according to the second invention, the electric power supplied to the electric heater is reduced at the start of energization, so that it is possible to prevent excessive boiling of hot water generated at the start of energization.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view illustrating an example of a heating tube according to the first embodiment.
FIG. 3 is a flowchart illustrating control of a control unit according to the first embodiment.
FIG. 4 is a schematic view showing a second embodiment of the present invention.
FIG. 5 is a flowchart illustrating control of a control unit according to the second embodiment.
FIG. 6 is a view showing a conventional electric water heater.
FIG. 7 is a cross-sectional view of a heating pipe of a conventional electric water heater.
FIG. 8 is a diagram showing an example of a wax valve.
FIG. 9 is a diagram showing excessive boiling of hot water in the heating tube.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hot water storage tank 2 Upper pipe 3 Lower pipe 10 Heating pipe 10A Outlet 20 Control means

Claims (3)

A hot water storage tank for storing the boiling water, a heating pipe provided with an upper flow outlet having a temperature flow control valve that opens when the boiling water reaches a predetermined temperature, and connecting the lower part of the hot water storage tank and the lower part of the heating pipe. In an electric water heater comprising a lower pipe and an upper pipe connecting an outlet of the heating pipe and an upper part of the hot water storage tank,
Two electric heaters provided in the heating tube for boiling hot water in the heating tube;
Control means for supplying electric power to the one electric heater and turning off the other electric heater for a predetermined time from the start of energization and for supplying electric power to the two electric heaters after a predetermined time An electric water heater characterized in that: A hot water storage tank for storing the boiling water, a heating pipe provided with an upper flow outlet having a temperature flow control valve that opens when the boiling water reaches a predetermined temperature, and connecting the lower part of the hot water storage tank and the lower part of the heating pipe. In an electric water heater comprising a lower pipe and an upper pipe connecting an outlet of the heating pipe and an upper part of the hot water storage tank,
An electric heater provided in the heating pipe, for boiling hot water by supplying a predetermined electric power,
Control means for supplying power less than a predetermined power to the electric heater only for a predetermined time from the start of energization, and supplying predetermined power to the electric heater after a predetermined time. . The electric water heater according to claim 1, wherein the temperature flow control valve is a wax valve.

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