JP3678215B2 - Electric water heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric water heater mainly used in a general home or office.
[0002]
[Prior art]
Conventionally, this type of electric water heater will be described with reference to FIGS.
[0003]
In FIG. 5, reference numeral 1 denotes an outer shell that forms a side surface and a bottom surface, and is provided with a handle 2 for carrying. Reference numeral 3 denotes a lid which rotates around the hinge 4. An operation unit 5 performs various operation controls. Reference numeral 6 denotes a power feeding unit.
[0004]
In FIG. 6, reference numeral 7 denotes a water storage container built in the outer shell 1, and the upper part thereof is closed with the lid 3. 8 is a fixed plate fixed to the bottom of the container 7, 9 is a water pump attached to the fixed plate 8 with screws or the like, 10 is a control circuit for performing electrical control, and 11 is a thermal sensor in the center of the bottom of the container 7. Is a temperature detection element provided in the, and detects the hot water temperature and sends a signal to the control circuit 10. Reference numeral 12 denotes a heating device that is provided at the bottom of the container 7 and includes a heater that heats the liquid in the container. The heating device 12 includes a water heater 13 with a power consumption of 1000 W and a heat retaining heater 14 with a power consumption of 100 W, each of which is connected to a common terminal 15. The other ends are connected to a water heater terminal 16 and a heat retaining terminal 17, respectively. The water heater 13 and the heat retaining heater 14 form a heat generating member. Reference numeral 18 denotes a relay terminal. Reference numeral 19 denotes a power supply terminal of the power supply unit 6, one end connected to the control circuit 10 and the other end connected to the thermal fuse 20. The thermal fuse 20 is sandwiched between the fixed plate 8 and the container 7 so as to be in thermal contact with the bottom of the container 7.
[0005]
As shown in FIG. 7, the thermal fuse 20 is generally configured by sandwiching a low-melting-point metal pellet 21 between lead terminals 22, and when the temperature becomes equal to or higher than a set temperature, the pellet 21 melts and interrupts the electric circuit. When the temperature at the bottom of the container 7 rises abnormally, the temperature fuse 20 rises following this temperature rise. When the temperature reaches the abnormal temperature, the built-in pellet 21 melts and the lead terminal 22 is electrically disconnected. The power supply from the power supply unit 6 is stopped. Therefore, the abnormal temperature rise at the bottom of the container 7 stops.
[0006]
In the electric water heater having the above configuration, when water is supplied to the container 7 and the power is supplied from the power supply unit 6, the control circuit 10 controls the power supply to the heating device 12, and the temperature detection element 11 detects the hot water temperature in the container 7. Do a kettle. When hot water is boiled, it automatically keeps warm. When hot water is desired, the operation unit 5 is operated to drive the centrifugal pump 9 to supply hot water.
[0007]
Here, the thermal fuse 20 is activated when the temperature of the heating device 12 exceeds a set temperature during abnormal heat generation. The thermal fuse 20 is connected to the heating device 12 in series. When the thermal fuse 20 is activated, the electric circuit is opened, so that the energization to the heating device 12 is stopped and the abnormal temperature rise is stopped.
[0008]
[Problems to be solved by the invention]
However, in the conventional configuration, the thermal fuse 20 is attached in the vicinity of the heating device 12, but the heat transfer is conducted from the heating device 12 to the bottom of the container 7 and from the bottom of the container 7 to the vicinity of the thermal fuse 20. Then, it is transmitted to the pellet 21 of the thermal fuse 20 through the insulating film on the outer surface of the thermal fuse 20. However, in recent years, the power consumption of the heating device 12 has been increased in order to perform the water heating quickly. Accordingly, there is a problem that the temperature of the heating device 12 reaches a high temperature before the thermal fuse 20 is activated in the event of an abnormality, causing thermal damage to the container 7 and the centrifugal pump 9 and being difficult to reuse.
[0009]
The present invention solves the above-described conventional problems, and an object thereof is to provide an electric water heater that can quickly cut off an electric circuit at an abnormal temperature.
[0010]
[Means for Solving the Problems]
To achieve the above object, an electric water heater of the present invention, the heating device and a terminal member for conducting the heat-generating member, formed of a low-melting metal member to melt the pin member during abnormal temperature, the terminal member The opposite end of the substantially horizontal connecting portion extends substantially vertically, is electrically and thermally connected to the heat generating member, is passed vertically through the guide hole, and the connecting portion abuts on the upper end surface and is locked. It is held by the holding unit and is continuously held even when melted .
[0011]
Thereby, when the heating device becomes abnormally high temperature, the terminal member melts by the heat from the heating device and the energization to the heating device is stopped, so that the power supply can be cut off while the damage to the heating device is small. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The invention described in claim 1 includes a container for storing water and a heating device for heating the liquid in the container, and the heating device has a heating member and a terminal member for energization, and the terminal member is The terminal member is formed of a low melting point metal member that melts at an abnormal temperature. The terminal member extends substantially vertically at the opposite end to the substantially horizontal connection portion, and is electrically and thermally connected to the heating member, and is perpendicular to the guide hole. The electric heater is held by a holding portion that is passed through and is held in contact with the upper end surface, and is continuously held even when melted . The terminal member can be quickly melted to stop the power supply to the heat generating member.
[0013]
Further, when the heat generating member reaches an abnormally high temperature, the heat is quickly conducted to the terminal member of the low melting point metal member, and the terminal member is melted to stop energization to the heat generating member.
[0014]
Further, even when the terminal member is melted, it is held in its original position so as not to come into contact with other members.
[0015]
According to a second aspect of the invention, the terminal member, by an electric water heater according to請Motomeko 1 melted during boil-dry container, the terminal member functions as normal terminal, during boil-dry container terminal A part of the member can be melted to interrupt the electric circuit.
[0016]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
(Example 1)
1 and 2 show an electric water heater in Embodiment 1 of the present invention, and the basic configuration of the electric water heater is the same as that of the conventional example, so the same parts are denoted by the same reference numerals and the description thereof is omitted.
[0018]
As shown in the figure, a convex flat portion 30 having a substantially circular shape and a flat upper surface is formed at the bottom of the container 7, and the heating device 12 is attached to the lower surface of the convex flat portion 30. The configuration of the heating device 12 is such that the upper mica 31 located above, the lower mica 32 located below, the water heater 13 with power consumption of 1000 W, and the heat retaining heater 14 with power consumption of 100 W are wound around the mica 33 in two strips. And a terminal member 36, 38, 39 for energizing the heat generating part 34. The heat generating portion 34 is sandwiched between the upper mica 32 and the lower mica 33, and the water heater 13 and the heat retaining heater 14 constitute a heat generating member to which terminal members 36, 38, 39 are connected. Reference numeral 35 denotes a heat diffusion plate located between the convex flat portion 30 and the heating device 12.
[0019]
The terminal member 36 is a water heater terminal, and is configured such that the substantially horizontal connecting portion 37 is electrically connected to the end of the heater 13 and at the same time the heat of the heater 13 is directly conducted by heat conduction. An end opposite to the connection portion 37 of the terminal member 36 is formed so as to extend downward substantially vertically so that it can be connected to a Faston terminal or the like. The terminal member 36 is formed by pressing an aluminum plate material which is a low melting point metal member.
[0020]
Next, the terminal member 38 is a heat insulation terminal and is connected to the heat insulation heater 14. The terminal member 39 is a common terminal connected to the water heater 13 and the heat retaining heater 14. Both terminal members 38 and 39 have the same shape as the terminal member 36, and are both formed from an aluminum plate material which is a low melting point metal member.
[0021]
Reference numeral 40 denotes a blank mica, which is provided with a through hole 41 through which the extended portions of the terminal members 36, 38, 39 pass. Reference numeral 42 denotes a pressing plate formed of a molten aluminum plated steel plate, which is pressed by pressing the heating device 12 from below through the lower mica 32 and spot welded to the bottom of the container 7 to be fixed. Each terminal member 36, 38, 39 is pressed by the presser plate 42 and pressed by the water heater 13 and the heat retaining heater 14.
[0022]
Reference numeral 43 denotes a holding portion which is a terminal guide. The terminal members 36, 38, and 39 are vertically passed through the guide holes 44, and the connecting portion 37 is brought into contact with and locked to the upper end surface 45. The holding portion 43 is held through a fixing hole 46 provided in the holding plate 42 while the locking portion 47 is locked to a pair of claws 48 of the fixing hole 46. When the claw 48 is deformed with a simple tool, the holding portion 43 can be easily detached from the pressing plate 42, and the terminal members 36, 38, 39 can be replaced. Each terminal member 36, 38, 39 is locked to the upper end surface 45 of the holding portion 43 and does not fall by its own weight.
[0023]
The operation of the electric water heater configured as described above will be described.
[0024]
First, when water is put into the container 7 and the heating device 12 is energized, the liquid in the container will eventually boil. Then, the control circuit 10 described in the conventional example from the rate of change of the hot water temperature detects boiling through the temperature detection element 11 and stops energizing the heating device 12. At this time, the temperature of the connecting portion 37 of each terminal member 36, 38, 39 is about 200 degrees, and there is a margin with respect to the temperature at which aluminum melts 660 degrees.
[0025]
After the boiling detection, the control circuit 10 controls energization to the heating device 12 by a signal from the temperature detection element 11 that detects the temperature in the container 7 and keeps the temperature at a predetermined temperature.
[0026]
Next, the case where the energization control to the heating device 12 becomes impossible and the continuous energization mode is set will be described. If the hot water in the container 7 continues to boil continuously, the hot water in the container 7 will eventually disappear, and the convex flat portion 30 containing the heating device 12 will appear from the water surface. Since the heating device 12 further heats, the inside of the container 7 eventually becomes empty beyond the boiling temperature of 100 degrees, and the temperature of the convex flat portion 30 on the bottom surface of the container 7 rapidly increases. At this time, each of the terminal members 36, 38, 39 receives the heat generated by the water heater 13 and the heat retaining heater 14 by direct heat conduction, and the temperature rises at almost the same speed as the water heater 13 and the heat retaining heater 14. When the temperature of the bottom surface of the container 7 reaches about 660 degrees, each terminal member 36, 38, 39 reaches the melting point almost simultaneously and melts. At this time, for example, if the water heater 13 is at an abnormally high temperature, the terminal member 36 or the terminal member 39 receives the heat as direct conduction heat, and the connecting portion 37 is melted. Further, if the heat retaining heater 14 is at an abnormally high temperature, the terminal member 38 or the terminal member 39 is melted by the conduction heat. Since a metal such as aluminum melts rapidly when it reaches the melting point, it is possible to surely boil the water and open the electric circuit of the heater 13 and the heat retaining heater 14. When each terminal member 36, 38, 39 is melted at the same time, both ends of the heating device 12 are cut off, and energization to the heating device 12 can be cut off reliably.
[0027]
The terminal members 36, 38, and 39 are only partially melted at the connection portion 37, cut off the energization to the heating device 12, and are engaged with the upper end surface 45 of the holding portion 43 to continue after melting. And is held.
[0028]
If any one of the terminal members 36, 38, 39 breaks down due to melting or the like, the holding portion 43 can be removed from the holding plate 42 by deforming the claw 48 with a simple tool such as radio pliers. The member can be replaced.
[0029]
As described above, according to the first embodiment, when the abnormal temperature of the heating device 12 rises, any one of the connection portions 37 of the terminal members 36, 38, 39 is melted to interrupt the electric circuit of the heating device 12. Can do.
[0030]
(Example 2)
Next, FIGS. 3 and 4 show an electric water heater according to the second embodiment of the present invention, and the basic configuration is the same as that of the first embodiment. Therefore, the same parts are denoted by the same reference numerals and the description thereof is omitted.
[0031]
As shown in the figure, the heating device 50 is formed by pressing a stainless steel plate, and includes a water heater 51 and a heat retaining heater 52. These water heater 51 and heat retaining heater 52 form a heat generating member. Other configurations are the same as those of the first embodiment.
[0032]
As described above, according to the second embodiment, when the abnormal temperature of the heating device 50 rises, any one of the connection portions 37 of the terminal members 36, 38, 39 is melted to interrupt the electric circuit of the heating device 50. Can do.
[0033]
In Examples 1 and 2, although the low melting point metal member is aluminum, a low melting point material (between about 200 degrees and 800 degrees) such as zinc, strontium, or cerium may be used.
[0034]
【The invention's effect】
As described above, according to the electric water heater of the present invention, the heating device includes the heat generating member and the terminal member formed of the low melting point metal member, so that the heat of the heat generating member is transferred to the terminal member when the heat generating member is abnormally heated. The terminal member, which is a low melting point metal member, can be quickly conducted and melted to stop power feeding, and abnormal heat generation can be stopped.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a main part of an electric water heater showing Embodiment 1 of the present invention. FIG. 2 is a partial sectional view of the electric water heater. FIG. 3 is a main portion of an electric water heater showing Embodiment 2 of the present invention. FIG. 4 is a partial cross-sectional view of the electric water heater. FIG. 5 is a perspective view of a conventional electric water heater. FIG. 6 is a partial perspective view showing the internal configuration of the electric water heater. FIG. Perspective view with partly broken fuse [Explanation of symbols]
7 Container 12, 50 Heating device 34 Heat generating portion 36, 38, 39 Terminal member 43 Holding portion 50 Heater (heating device)

Claims (2)

A low melting point metal member comprising a container for storing water and a heating device for heating the liquid in the container, the heating device having a heat generating member and a terminal member for energization, and melting the terminal member at an abnormal temperature The terminal member extends substantially vertically at the opposite end to the substantially horizontal connecting portion, is electrically and thermally connected to the heat generating member, and passes vertically through the guide hole. An electric water heater that is held by a holding portion that is brought into contact with and locked to the water heater and that is continuously held even during melting . The electric water heater according to claim 1 , wherein the terminal member is melted when the container is empty.

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