JPH08167468A - Heating device - Google Patents

Abstract

PURPOSE: To provide a heating device which can secure the insulation and can safely stop the power feeding function even in the final period of the service life of an electric wire. CONSTITUTION: This heating device is composed of a heating body 1 to heat a liquid; a water pipe to pass the liquid; and a heat conductive metal part to integrally combine the heating body 1 and the water pipe. The heating body 1 is composed of an electric heating wire 4; an electric insulating member 5 to cover the electric heating wire 4; a tube form metal sheath 6 to cover the insulating member 5; an outer side electric insulating member 7 to cover the metal sheath 6; and an outer side metal sheath 8 to cover the outer side electric insulating member 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for an electric water heater which heats and keeps hot water.

[0002]

2. Description of the Related Art A conventional heating device of this type is shown in FIG.
As shown in an external plan view of a conventional heating device and FIG. 4 which is a partial cross-sectional view of the heating element, a sheathed heater 9 which is a heating element for heating a liquid, a water passage pipe 2 through which the liquid passes, and these sheathed heaters 9 are connected. In a heating device composed of a heat conductive metal part 3 that integrally connects the water pipes 2, the sheathed heater 9 has an electric heating wire 4, an electric insulating material 5 covering the electric heating wire 4, and the electric insulating material. There is one using a general sheathed heater composed of a tubular metal sheath 6 covering 5 (see, for example, JP-A-5-312406).

[0003]

In the above conventional heating device, in the case of an electric water heater using water as the liquid to be heated, the sheath heater 9 deteriorates the insulation performance of the electric insulating material 5 at the end of its life, and the insulation resistance increases. Due to local heat generation when the electric heating wire 4 is broken and the life of the electric heating wire 4 is broken, a short circuit phenomenon occurs between the electric charging part such as the electric heating wire 4 and the metal sheath 6, and the user of the electric water heater connects the water pipe 2 to the water pipe 2. There was a safety problem that there was a fear of electric shock through the water that passed through.

An object of the present invention is to safely stop the energizing function even at the end of life.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a heating element for heating a liquid, a water pipe through which the liquid passes, and a heating element and a water pipe are integrally formed. In a heating device composed of a heat conductive metal part to be coupled, the heating element is an electric heating wire, an electric insulating material covering the electric heating wire, a tubular metal sheath covering the electric insulating material, and the metal sheath. And an outer metal insulating sheath that covers the outer electrical insulating material and a tubular outer metal sheath that covers the outer electrical insulating material.

[0006]

With this structure, the metal portion normally transfers the heat generated by the heating element to the water pipe to efficiently heat the liquid. In addition, at the end of the life of the electric heating wire, the insulation performance of the electrical insulating material deteriorates and the insulation resistance decreases, and when the electric heating wire is disconnected from its life, the electric heating wire locally becomes thin and local heat is generated, resulting in electrical Even if a short circuit occurs between the heating wire and the inner metal sheath, the metal sheath blocks the effect of local heat generation, the outer electrically insulating material maintains a healthy insulating state, and the electric heating wire and the outer electrical sheath In the meantime, it acts to maintain an insulating state between the electric heating line, which is the electric charging unit, and the water pipe, and thus the electric charging unit and the heating liquid.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an external plan view of a heating device showing an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of the heating element.

In FIG. 1, a sheath heater 1 which is a heating element for heating a liquid and a water pipe 2 made of a stainless steel pipe for passing a liquid are integrally connected by a metal portion 3 made of a heat conductive aluminum alloy or the like. A heating device is configured.

In FIG. 2, the sheath heater 1 has a tubular shape made up of an electric heating wire 4, an electric insulating material 5 made of magnesium oxide powder or the like for covering the electric heating wire 4, and a stainless pipe for covering the electric insulating material 5. A metal sheath 6, an outer electrical insulating material 7 made of magnesium oxide powder or the like for covering the metal sheath 6, and a tubular outer metal sheath 8 made of a stainless pipe or the like for covering the outer electrical insulating material 7.
It consists of Therefore, the outer metal sheath 8 and the metal portion 3 are integrally connected.

Next, the operation of the above configuration will be described.

When the electric heating wire 4 is energized, heat is generated, and the heat is generated by the electric insulating material 5, the metal sheath 6, and the outer electric insulating material 7.
Further, heat is transferred to the metal portion 3 via the outer metal sheath 8. Therefore, the liquid flows through the inside of the water pipe 2, and the heat amount necessary for heating the liquid is supplied from the sheath heater 1 to the inside of the water pipe 2 through the metal portion 3.

When the heating device is used for a long time, the insulation performance of the electric insulating material 5 deteriorates at the end of its life, and the insulation resistance decreases,
Furthermore, when the electric heating wire 4 is broken in service life, the electric heating wire 4 is locally thinned, so that local heat is generated in this portion, and a short circuit phenomenon occurs between the electric heating wire 4 and the metal sheath 6. The influence of local heat generation at this time is blocked by the metal sheath 6, and the outer electrical insulating material 7 can be maintained in a healthy state.

Therefore, insulation is maintained between the electric heating wire 4 which is the electric charging portion and the outer metal sheath 8 and between the electric heating wire 4 and the water pipe 2, that is, between the electric charging portion and the heating liquid. In the insulated state, the electric heating wire 4 is broken, and the heating device stops the energizing function in a safe state for the user.

[0014]

As described above, according to the present invention, the heating device is constituted by the heating element for heating the liquid, the water pipe through which the liquid passes, and the heat-conductive metal portion integrally connecting the heating element and the water pipe. Therefore, the metal part normally transfers the heat generated by the heating element well to the water pipe and can efficiently heat the liquid,
The heating element is an electric heating wire and an electric insulating material covering the electric heating wire,
It consists of a tubular metal sheath that covers the electrical insulation material, an outer electrical insulation material that covers the metal sheath, and a tubular outer metal sheath that covers the outer electrical insulation material. The electrical insulation between the parts and the heated liquid is maintained, and it is safe for users even at the end of their life.
There is an effect that it is possible to provide a heating device in which the energized state is stopped.

[Brief description of drawings]

FIG. 1 is an external plan view of a heating device showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a heating element of the same.

FIG. 3 is an external plan view of a conventional heating device.

FIG. 4 is a partial cross-sectional view of the heating element of the same.

[Explanation of symbols]

 1 Heat generating element (sheath heater) 2 Water passage pipe 3 Metal part 4 Electric heating wire 5, 7 Electric insulating material 6, 8 Metal sheath

Claims (1)

[Claims] 1. A heating device comprising a heating element 1 for heating a liquid, a water passage pipe 2 through which the liquid passes, and a heat-conducting metal portion 3 integrally connecting the heating element 1 and the water passage pipe 2 in a heating device. The heating element 1 includes an electric heating wire 4, an electric insulating material 5 covering the electric heating wire 4, a tubular metal sheath 6 covering the electric insulating material 5, and an outer electric insulating material 7 covering the metal sheath 6. And a tubular outer metal sheath 8 that covers the outer electrical insulating material 7, and a heating device.