JPH0318445B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electric water heater for heating and keeping a stored liquid warm.

Conventional technology Conventional electric water heaters of this type are, for example,
As shown in Japanese Patent No. 59-37037, it had a configuration as shown in FIG. That is, a band-shaped heating element 2 is wrapped around the outer surface of a cylindrical container 1 with a bottom, and a temperature-sensitive reed switch 3 is wrapped around one end of a heat transfer fan 4 made of a non-magnetic and highly thermally conductive material. At the same time, a temperature control body 7 in which a temperature fuse 6 covered with an insulating material 5 is integrally wound around the other end of the heat transfer fan 4 is attached to a presser spring 1 having a pressing part 8 and a locking part 9.
0, the temperature control body 7 was held in close contact with the bottom surface of the container 1.

Problems to be Solved by the Invention In such a conventional configuration, a band-shaped heating element 2 is wrapped around the outer surface of the container 1, and a temperature-sensitive reed switch 3 and an insulating material 5 are attached to the bottom surface of the container 1. Since the heat receiving part of the temperature control body 7, which is wrapped around the temperature fuse 6 coated with a heat transfer fan 4 made of a non-magnetic material with good thermal conductivity, is held in close contact with the entire surface by a pressing spring 10, the temperature sensing If a temperature controller such as the reed switch 3 is short-circuited, the temperature fuse 6 will not operate (melt) until the liquid stored in the container 1 evaporates and the temperature reaches a dry state, causing each part of the electric water heater to malfunction prematurely. There was a problem of deterioration. Furthermore, even if the heating element 2 loosens or deteriorates due to repeated thermal expansion/contraction differences, the temperature of the temperature fuse 6 is controlled by thermal conduction, which is not necessarily desirable from a safety standpoint. Ta. That is, there is also a problem in that the temperature fuse 6 does not operate even if the heating element 2 has deteriorated to the point where it falls off.

The present invention solves these problems,
The purpose of the present invention is to provide an electric water heater that is excellent in terms of the correlation between a heating element and a temperature control device, safety, and durability.

Means for Solving the Problems In order to solve the above problems, the present invention has a cylindrical shape with a bottom and a heat transfer surface projecting in a substantially D shape, and a heating element is attached to the bottom back side of the container. A heat-receiving part is formed by integrally wrapping a temperature-sensitive reed switch at one end of a good heat-conducting member made of a magnetic material and a temperature fuse covered with an insulating material at the other end. The heat receiving part on the temperature sensitive reed switch side is brought into contact with the temperature detection surface cut into a shape, and the heat receiving part on the temperature fuse side is inserted through a cutout hole provided in a heat shield plate covering the lower surface of the heating element. It is installed so as to face below the heating element.

Function According to this configuration, the temperature fuse receives the heat of the heating element from the temperature sensor at the bottom of the container through the heat-sensitive part and the radiant heat radiated downward by the heating element, resulting in a synergistic effect of the heat of both. So, even if the temperature-sensitive reed switch or temperature controller is short-circuited, it will be affected by the radiant heat from the heating element, and the temperature fuse will operate sooner than the liquid stored in the container will evaporate and become dry. Therefore, rapid temperature rise in each part can be prevented. Further, even if the heating element deteriorates, the same effect as the former can be obtained.

Examples Examples of the present invention will be described below in Figures 1 to 3.
This will be explained with reference to the figures. In the figure, reference numeral 11 indicates an outer peripheral side edge 11 with a central portion protruding upward in a substantially D-shape.
This heat transfer surface 11 has a temperature detection surface 11c on the surface of the D-cut peripheral edge 11b.
A metal container 12 is formed by having an outer edge portion liquid-tightly fixed to the lower end of the cylindrical body by means such as welding. Reference numeral 13 denotes an exterior body that encloses the container 12 with a space therebetween. A heating element 14 is attached to the lower surface of the heat transfer surface 11, and the heating element 14 is formed by integrally wrapping a first heating wire and a low-power second heating wire, and sandwiching the upper and lower parts with an insulating material. ing. Further, the heating element 14 has a through hole in the center, and a presser foot is provided on the lower surface of the heat transfer surface 11 by a heat diffusion plate 15 and a back plate 16 made of a material with good thermal conductivity and having an outer peripheral side part 15a. It is fixedly built-in by spot welding or the like to form a heating element.

Note that the back plate 16 is provided with a notch 16a of an appropriate size on the D-cut outer peripheral side. Further, a substantially Z-shaped container fitting 18 for fixing a heat shield plate 17 that substantially covers the bottom surface of the container 12 is fixed to this back plate 16 .

The heat shield plate 17 has a notch 16 in the back plate 16.
A U-shaped notch hole of an appropriate size is provided corresponding to a. Further, a temperature controller 19 is attached to the center of this heat shield plate 17 by a mounting spring 20, a temperature sensitive reed switch 22 is provided at one end of a good heat conductive member 21 made of a non-magnetic material, and an insulated switch is provided at the other end. A temperature fuse 23 covered with a material is wound together to form a heat receiving part, and a temperature sensing surface 11a cut into a substantially D shape of the protruding part 12 of the container 12 is connected to the temperature sensing reed switch 22 side. The heat receiving part of the temperature fuse 23 is placed in contact with the heat receiving part by placing both ends of the insulating material for covering the temperature fuse on both edges of the notch hole provided in the heat shield plate 17. It is attached by a pressing spring 24 so as to face below the heating element 14 through the heating element 14 . The heat shield plate 17 is attached to the bottom surface of the container 12 through the container fitting 18 so that the temperature controller 19 and the heat receiving parts of the integrated temperature-sensitive reed switch 22 and temperature fuse 23 are in close contact with each other. It is fixed by a metal fitting 25. A wiring board 26 is attached to the heat shield plate 17. 27 is a water level gauge equipped on the cylindrical outer wall of the container 12. The lead wires 28, 29, and 30 of the heating element 14 are located at a portion facing a substantially D-shaped D-cut portion of the bottom protrusion of the container 12.

The first heating wire is electrically connected to the temperature controller 19, and the second heating wire is electrically connected to the temperature-sensitive reed switch 22 to form a parallel circuit, and a temperature fuse 23 is connected in series. It constitutes an electric water heater.

In the above configuration, a liquid is stored in the container 12,
When electricity starts, the heating element 14 is heated and heat is transferred to the liquid via the heat transfer surface 11. At the same time, heat is also diffused toward the outer peripheral side through the heat diffusion plate 15. The heat transferred to the back plate 16 by the heat diffusion plate 15 is transferred to the outer peripheral side and is used to heat the liquid. When the liquid reaches a certain temperature, the heat transfer surface 11
a temperature controller 19 coupled to the central part of the
The first heating wire is turned off, and only the low-power second heating wire is energized. When the liquid reaches a certain temperature by further slow temperature rise, the temperature-sensitive reed switch 22 is activated and turns off. When the liquid temperature drops, the temperature-sensitive reed switch 22, which is turned on before the temperature controller 19, is activated and turned on, and thereafter the on-off cycle is repeated to ensure a low-power heat retention state. Furthermore, if the temperature controller 19 remains on due to a failure, the electrical circuit of the temperature fuse 23 will melt due to heat conduction from the temperature sensing surface 11c on the bottom of the container 12 and radiant heat from the back plate 16, causing the electrical circuit to melt. The power to the entire water heater is turned off to ensure safety.

As described above, the heating element 14 is attached to the back side of the bottom of the container 12 which is cylindrical with a bottom and has the heat transfer surface 11 projected in a substantially D shape, and the temperature-sensitive reed switch 22 is attached to one end of the good heat conduction member 21. A temperature fuse 23 coated with an insulating material is integrally wound around the other end to form a heat receiving part, and the temperature sensing lead is attached to the temperature sensing surface 11c cut into a substantially D shape of the container 12. The heat receiving part on the switch 22 side is brought into contact with the heat receiving part on the temperature fuse 23 side, and the heat receiving part on the temperature fuse 23 side is inserted into the heat generating element 14 through a notch provided in the heat shield plate 17 covering the lower surface of the heat generating element 14.
Since the temperature fuse 23 is mounted facing downward, the temperature fuse 23 receives heat conduction and radiant heat from the heating element 14, and due to the mutual effect of the two, the temperature-sensitive reed switch 22 and the temperature controller 19 may be short-circuited. However, container 12
The temperature fuse 23 operates (melts down) sooner than the liquid stored in the electric water heater evaporates and the electric water heater becomes dry, thereby preventing a rapid temperature rise in each part of the electric water heater. Also, if the heating element 14 thermally expands,
Even if loosening and deterioration occur due to repeated thermal contraction differences, the same effect as the former can be obtained.

In the embodiment, the temperature sensitive reed switch 22 and the temperature fuse 23 are wrapped together with the good heat conductive member 21, but only the temperature fuse 23 is wrapped with the good heat conductive member 21, and the heat receiving part Container 12
Needless to say, the same effect can be obtained by attaching the temperature fuse 23, which is wrapped tightly to the bottom of the heating element 14, so as to face below the heating element 14.

Effects of the Invention As described above, according to the present invention, the bottomed cylindrical shape is approximately D
In the heat-receiving part of a temperature-sensitive reed switch and a temperature fuse, a heat-generating element is attached to the back side of the bottom of a container that has a heat-transfer surface projected in a shape, and is integrally wrapped around a good heat-conducting member made of a non-magnetic material. The temperature-sensitive reed switch side is in contact with the temperature sensing surface cut into a roughly D-shape on the protruding part of the container, and the temperature fuse side is installed so as to face below the heating element. It is possible to improve the correlation with safety, safety, and durability.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of the main parts of an electric water heater showing an embodiment of the present invention, FIG. 2 is a plan view of the main parts of the water heater, FIG. 3 is a vertical cross-sectional view of the water heater, and FIG. 1 is a perspective view of a main part of a container in a conventional water heater. 11...Heat transfer surface, 11c...Temperature detection surface, 12
... Container, 14 ... Heating element, 19 ... Temperature controller, 21 ... Good heat conduction member, 22 ... Temperature-sensitive reed switch, 23 ... Temperature fuse, 24 ... Pressing spring.

Claims (1)

[Scope of Claims] 1. A heating element is attached to the back side of the bottom of a container having a cylindrical shape with a bottom and a heat transfer surface projected in a substantially D shape, a temperature controller is attached to the center of the bottom of the container, and a non-magnetic A heat-receiving part is formed by integrally wrapping a temperature-sensitive reed switch at one end of a good heat-conducting member consisting of a body and a temperature fuse covered with an insulating material at the other end. The heat receiving part on the temperature sensitive reed switch side is brought into contact with the temperature sensing surface cut into a shape, and the heat receiving part on the temperature fuse side is inserted through the cutout hole provided in the heat shield plate covering the lower surface of the heating element. An electric water heater characterized by being installed facing downward from a heating element. 2. The electric water heater according to claim 1, wherein the temperature fuse is wound solely around one end of a good heat conductive member.