JPH045449B2 - - Google Patents

Description

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

Conventional technology Conventionally, this type of heating element has been developed by, for example,
The one shown in Japanese Patent No. 59-82816 is known. As shown in FIGS. 7 to 9, the central part of the bottom surface of the inner container 1 of the electric pot protrudes upward, and the main heating wire 3 is attached to the back surface of the heat transfer body 2, which has a peripheral edge part 2a formed on the outer periphery. Insulating plates 7 and 8 are laminated on the upper and lower sides of a heat generating plate 6 in which the auxiliary heat generating wire 4 is integrally wound around a substrate 5, and a through hole is provided in the center of the heat generating plate 6. The heat generating plate 6 is built into the lower surface of the heat transfer plate 2 in a compressed state by a heat diffusion plate 9 having good thermal conductivity and a backing material 10 having a through hole in the center and an outer peripheral edge 9a. A heating element portion is formed.

Problems to be Solved by the Invention In such a conventional configuration, since the area of the board 5 is limited, the winding pitch of the main heating wire 3 and the auxiliary heating wire 4 is inevitably small, which causes problems during winding work. If the main heating wire 3 and the auxiliary heating wire 4 are short-circuited due to slack, etc., or if the winding pitch is increased to prevent short-circuiting, the power density per unit area of the main heating element 3 and the auxiliary heating wire 4 will decrease. Not only does this cause a big problem in terms of reliability and durability, but also the various parts that make up the electric pot are not necessarily desirable due to the effects of temperature rise. In addition, especially for the auxiliary heating wire 4 for low power use, a heating wire with a large resistance value, that is, a small cross-sectional area, is used in order to satisfy a predetermined amount of power, and the tension during winding of the auxiliary heating wire 4 is reduced. This caused serious problems in terms of workability, such as breakage.

The present invention solves these problems,
The object of the present invention is to provide an electric heating element that has excellent durability and safety, and improves the workability of winding the heating wire.

Means for Solving the Problem In order to solve this problem, the present invention provides a container having a cylindrical shape with a bottom and a heat exchanger plate protruding from the bottom, and a container having both upper and lower surfaces covered with an insulating material on the back side of the bottom of the container. It consists of a heat generating board 1 and a second heat generating board whose power consumption is lower than that of the first heat generating board and whose upper and lower surfaces are covered with insulating material. It is equipped with a heating element having a heat diffusion plate with good thermal conductivity that is partially in thermal contact with the heat transfer plate.

Effects With this configuration, two types of heating wires are wound on separate heating panels, so there is no short circuit due to sagging unlike when integrally wound, and the winding pitch can be made smaller, allowing the length of the heating wire to be reduced. As a result, the cross-sectional area of the heating wire can be increased, and durability can be significantly improved.
In addition, in order to meet the specified amount of power, especially for small power heating wires, it is necessary to use a heating wire with a high resistance value, that is, a small cross-sectional area, but in this case, the cross-sectional area of the wire can also be increased. This not only improves durability, but also eliminates concerns about wire breakage due to tension during winding work, and improves workability. In addition, when actually heating the liquid in the container, the heat conduction path to the liquid in the container is established by energizing the first and second heat generating panels disposed above and below the heat diffusion plate. Looking at , heat is transferred from the top surface of the upper heating plate to the liquid via the heat conducting plate of the container, and heat is transferred from the bottom surface of the upper heating plate and the top surface of the lower heating plate during this time. When heated, heat is transferred from the heat transfer plate of the container to the liquid through at least the peripheral edge of the provided heat diffusion plate with good thermal conductivity, which is in thermal contact with the heat transfer plate that forms the bottom of the container, and the heat is transferred to the liquid from the heat-generating plate below. Heat is transferred to the liquid from the outer periphery of the bottom surface of the container via the backing material from the bottom surface. Therefore, the heat diffusion plate installed between the upper and lower heating plates effectively guides the heat generated between the upper and lower heating plates to heating the liquid, so there is no heat buildup, and this prevents the temperature of the heating wire from reaching extremes. Since there is no significant rise, the life of the heating wire can be extended. In addition, because of this, there is little temperature difference between the front and back surfaces of the upper and lower heating plates, and there is little difference in the amount of thermal expansion of the heating wires on the front and back surfaces due to temperature rise. Since no unreasonable stress is applied to the bent portion, durability against wire breakage and the like can be significantly improved.

Embodiment Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 to 6.

In the figure, reference numeral 11 denotes a heat transfer plate whose central portion projects upward in a substantially D-shape to form a peripheral edge 11a.
A metal liquid storage container 12 is formed by fixing its outer edge liquid-tightly to the lower end of the cylindrical body by means such as welding.
is formed. 27 is an exterior body (water heater body) that encloses the container 12 with a space therebetween. A heating element portion 14 is attached to the lower surface of the heat transfer plate 11 via a flat heat conduction plate 13 made of, for example, aluminum or surface-treated steel plate with good thermal conductivity. This heating element part 14 has a peripheral edge part 15a on a flat plate-like outer periphery, and this peripheral edge part 15a is made of aluminum or surface-treated steel plate which is in at least thermal contact with the inner wall of the peripheral side edge 11a at the center of the bottom surface of the container 12. A first heat generating plate 1 disposed above and below a flat plate surface of a heat diffusion plate 15 having good thermal conductivity such as
6 and a second heat generating board 17, the first heat generating board 1
6 has a main heating wire 19 wound around a substrate 18 and has insulating plates 20 and 21 on the top and bottom, and a second heating board 17 has an auxiliary heating wire 23 having a smaller power consumption than the main heating element 19 on the substrate 22. It is wound and has insulating plates 24 and 25 on the top and bottom. This heating element portion 14 and the heat conductive plate 1
3 has a through hole in the center, and these are formed by a backing material 26 of good thermal conductivity such as a surface-treated steel plate, which has a central part protruding upward, has an outer peripheral side part 26a, and has a through hole in the center.
Therefore, the heat exchanger plate 11 is mounted with a pressing allowance provided on the lower surface thereof.

With this configuration, the main heating line 1
9 and the auxiliary heating wire 23 are wound on separate boards 18 and 22, so there is no need to worry about short circuits and disconnections due to slack in the wires, unlike when they are wound on one board, and the winding pitch is small. Therefore, the length of the heating wire can be increased even with the same power consumption.
As a result, the cross-sectional area of the heating wire can be increased, and durability can be significantly improved. In addition, the auxiliary heating wire 23, which has a small power consumption, must have a large resistance value, that is, a heating wire with a small cross-sectional area, in order to satisfy a predetermined amount of power. This not only improves durability, but also improves durability.
Eliminates the worry of wire breakage due to tension during winding work,
Workability can be improved. Also, considering the case where the liquid in the container 12 is actually heated and kept warm, first, during heating, the main heating element 19 and the auxiliary heating wire 23 are energized at the same time, and when the liquid temperature reaches a certain temperature, the temperature controller automatically turns on the power. Switch to keep warm. In other words, only the auxiliary heating wire 23 is energized via another temperature controller to keep the liquid temperature constant.

In this structure, the heat conduction paths when heating and keeping the liquid warm are almost the same, so to explain heating as a representative example, by energizing the first and second heating plates 16 and 17, the heat diffusion plate 15 is heated. Heat is transferred from the upper surface of the first heat generating plate 16 disposed on the upper side to the liquid from the heat transfer plate 11 of the container 12 via the insulating plate 20 and the heat conduction plate 13, and is transferred to the lower side of the heat diffusion plate 15. Heat is transferred from the bottom surface of the disposed second heat generating plate 17 to the liquid from the outer periphery of the bottom surface of the container 12 via the insulating plate 25 and the backing material 26, and the heat is transferred to the liquid from the bottom surface of the first heat generating plate 16 and the second heat generating plate. From the top surface of 17, the respective insulating plates 21 and 24
from the container 1 via the peripheral edge 15a of the heat diffusion plate 15.
Heat is transferred to the liquid from the peripheral side edge 11a of the protrusion on the bottom surface. Therefore, due to the action of the heat diffusion plate 15, the first
Since there is no accumulation of heat generated between the lower surface of the heat generating plate 16 and the upper surface of the second heat generating plate 17, there is no extreme temperature rise in the main heat generating line 19 and the auxiliary heat generating line 23. There is little temperature difference between the front and back surfaces of the two heat generating plates 16 and 17, and there is little difference in the amount of thermal expansion between the front and back heat generating wires due to temperature rise. No undue stress is applied to the wire bending portion, and durability against wire breakage and the like can be significantly improved. Furthermore, even when electricity is applied without any liquid in the container 12, that is, in the dry firing state, the heat dissipation plate 15 radiates the heat generated between the two heating plates 16 and 17 to the container 12, so that the heating wire due to heat storage is reducing the negative impact on Furthermore, of the two heating panels 16 and 17, the first
Since the heating plate 16 is placed above the heat diffusion plate 15, it is close to the liquid in the container 12, so the amount of heat transferred to the liquid is larger than when it is placed below. It is possible to reduce the temperature rise of the heating wire 19, and as a result, it is possible to improve the durability life of the main heating wire 19.

Effects of the Invention As described above, according to the present invention, the heating element portion is
and a second heat-generating plate, and between both heat-generating plates, at least a heat diffusion plate with good thermal conductivity that is in thermal contact with the heat transfer plate during heating is arranged, and the bottom of the container is formed into a cylindrical shape with a bottom by the back plate. Since it is attached to the lower surface of the heat exchanger plate, it has excellent durability and has the effect of improving the workability of winding the heating wire.

[Brief explanation of drawings]

1 to 6 show an embodiment of the present invention, in which FIG. 1 is an exploded perspective view of an electric heating element, and FIG.
and b are a sectional view and an enlarged sectional view of a main part of an electric water heater equipped with a heating element, FIG. 3 is a partially cutaway plan view of the heating element, and FIG. 4 is a plan view of the first heating panel.
Fig. 5 is a plan view of the second heating panel, Fig. 6 is an overall sectional view of the electric water heater, Figs. 7 to 9 show conventional examples, and Fig. 7 is an exploded perspective view of the main parts of the electric heating element. 8 is a plan view of the heating panel, and FIG. 9 is a sectional view of the main parts of the electric water heater. 11...Heat transfer plate, 12...Container, 13...Heat conduction plate, 14...Heating element part, 15...Heat diffusion plate, 1
5a... Peripheral portion, 16... First heat generating plate, 17...
...Second heat generating board, 18...Substrate, 19...Main heat generating line, 20, 21...Insulating plate, 22...Substrate, 23
...Auxiliary heating wire, 24, 25...Insulating plate, 26...
...Back material.

Claims (1)

[Scope of Claims] 1. A first heat generating plate whose upper and lower surfaces are covered with an insulating material on the back side of the bottom of a container having a bottomed cylindrical shape and a heat transfer plate protruding from the bottom, and this first heat generating plate. and a second heat generating plate that consumes less power and whose upper and lower surfaces are covered with an insulating material, and a good heat generating plate that is at least partially in thermal contact with the heat transfer plate when heated between the first and second heat generating plates. An electric heating element equipped with a heating element equipped with a thermally conductive heat diffusion plate. 2. The electric heating element according to claim 1, wherein the first heating plate is positioned above the heat diffusion plate and the second heating plate is positioned below.