JPH06168783A - Electrothermal converter and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an electrode structure for an outer cylindrical member and a method for the manufacture thereof, ensuring stable discharge state, particularly a less abrasion rate for a tungsten alloy cathode at the outer cylindrical member and allowing long service life to be expected, regarding an electrothermal converter for heating water on DC arc plasma discharge. CONSTITUTION:A tungsten alloy ring member W is buried in a peripheral groove 2a recessed along the internal surface of an outer cylindrical member 2 of copper in such a way as having the upper surface thereof exposed, thereby constituting a cathode. Also, a manufacturing method is applied, using upper and lower separate molds M1 and M2 for integrally casting the member W.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrothermal converter, and more particularly to a structure of a discharge cathode part of an electrothermal converter which utilizes generated heat of arc plasma and a method for manufacturing the same.

[0002]

2. Description of the Related Art Most electrothermal converters used in, for example, conventional electric instant water heaters utilize heat generated by an electric resistor, but for use in ordinary household use, for example. Since it is extremely large, it was common to use hot water storage type. On the other hand, Japanese Patent Laid-Open No. 1-988
Japanese Patent Laid-Open No. 54-54 discloses a novel electric heating instantaneous water heater that utilizes the heat generated by an arc plasma, which has the characteristic that this type of instantaneous water heater can be greatly miniaturized. FIG. 3 shows an axial center sectional view of a schematic configuration showing the principle of the electrothermal converting portion.

This electrothermal converting portion is composed of double cylindrical members 1 and 2 and a outer container 3 which are arranged concentrically with each other, and each space 9 of the first, second and third layers is arranged from the inside. 4,10
To form an inner cylindrical member, 2
Indicates an outer cylindrical member, and 3 indicates an outer peripheral container. The inner and outer cylindrical members 1 and 2 are made of a material having high thermal conductivity such as Cu, and the second space 4 having an annular cross section formed between them is used as a discharge space. At the outer longitudinal center of the cylindrical member 1 and the inner longitudinal center of the outer cylindrical member 2, annular discharge electrode portions 5 and 6 made of a Cu material are provided so as to be convexly opposed to each other. Both ends of each of the cylindrical members 1 and 2 are hermetically fixed to each other by a lid member 7 made of an annular insulating material, and air or an inert gas, or a mixture of an inert gas and another gas, such as Ar, is provided in the internal space. It is filled with Ne gas or the like. It should be noted that one end of the outer peripheral container 3 is closed by a disk 8 and the inner space (first space) of the inner cylindrical member 1 is a water channel 9.
Is supplied with cold water 12 as a medium to be heated in the direction of the arrow in the figure, and flows out in the direction of the arrow in the figure through a water channel 10 of an annular cross-sectional space (third space) formed between the outer and inner cylindrical members 3/2. Is configured to.

When a DC high voltage is applied to each of the discharge electrodes 5, 6 from the external power source 13, an arc plasma 11 is formed between these electrodes 5, 6. This arc plasma 11
Is a magnetic field 1 generated by, for example, a ring-shaped permanent magnet (not shown) arranged at the outer peripheral positions corresponding to the electrodes 2 and 3 of the outer peripheral container 3.
4, the magnetic field 14 and the arc plasma 11 interact with each other to continuously move in the circumferential direction.

With the above structure, the inner cylindrical member 1
Heated water 12 such as city water introduced into the water channel 9
Is configured so that the heat generated by the arc plasma 11 is absorbed from the respective surfaces of the cylindrical members 1 and 2 to instantly become hot water and can be supplied to the outside through the water channel 10 in the arrow direction.

When the discharge electrodes 5 and 6 are made of the same copper material as the cylindrical members 1 and 2 in the above-described structure, the electrode 6 on the cathode side is particularly worn out, resulting in a short service life. Since the gas pressure in the space 4 tends to increase and a short circuit or the like due to the generation of metal powder or the like tends to occur, it has been attempted to make the cathode 6 made of an alloy containing tungsten as a main component as a countermeasure.

[0007]

An outer cylindrical member 2 made of copper.
In order to fix a ring-shaped member W of, for example, a tungsten alloy manufactured by the powder metallurgy method as the cathode 6 on the inner surface of the ring-shaped member, a ring-shaped member manufactured in advance is shown in FIG. A method has been adopted in which the (cathode) W is inserted into the inner diameter portion of the outer cylindrical member 2 made of copper, and the brazing material B is piled up for brazing.

However, in the fixing method as described above, the work is difficult because the inner side of the cylindrical portion is brazed, a gap is easily formed, and electrical contact tends to be insufficient. In addition, the clearance / bonding of dissimilar materials deteriorates thermal conductivity, which adversely affects performance / life. The present invention has been made in view of the above problems of the structure / method of the conventional example, and provides a structure / manufacturing method of an outer cylindrical member of this kind which is excellent in electric and heat conduction characteristics and is easy to manufacture. It is an object.

[0009]

Therefore, according to the present invention, the inner, outer double cylindrical member and the outer peripheral container arranged concentrically are arranged in order from the inside to the first, second and third spaces, respectively. And heating the fluid to be heated in the first and third spaces, applying a DC voltage to the second space to form arc plasma, and raising the temperature of the fluid to be heated by the generated heat. In the electrothermal converter described above, the outer cylindrical member is used as a discharge cathode side, the inner cylindrical member is used as a discharge anode side, and for the cathode, the circumference of the inner surface of the outer cylindrical member made of copper is recessed. As a method of manufacturing the outer cylindrical member having a tungsten alloy ring-shaped member buried so that its surface is exposed in the groove and having a discharge cathode of this electrothermal converter, the inner circumference thereof is A ring-shaped tungsten alloy as the cathode, which is produced in advance, by using a vertically divided mold for casting, which has a cavity corresponding to the outer shape of the outer cylindrical member in a state where a ring-shaped cathode member having a rectangular cross section is convexly provided After closing the two molds by interposing the members between the upper and lower split molds so that the outer periphery of the mold projects from the inner surface of the cylindrical portion of the cavity, molten copper is injected from an injection hole formed at the top of the cavity. It is intended to achieve the above-mentioned object by being configured to be cast by pouring.

[0010]

With the above-described structure / manufacturing method of the present invention, the work is easy, and due to the heat shrinkage of the copper during the cooling of the integral casting, the fitting / contact between the copper and the tungsten-based electrode is completely completed. Since it is carried out, it has excellent electrical / thermal conductivity characteristics and improved performance / life.

[0011]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is an explanatory view of an embodiment of a method of manufacturing an outer cylindrical member with a cathode according to the present invention, and FIG. 2 is a vertical half sectional view of an outer cylindrical member manufactured by this method. Figure 1 (a)
Shows a tungsten alloy ring-shaped member W for a cathode, which is manufactured in advance by powder metallurgy or the like. (B) The figure shows an upper mold M in which this ring-shaped member W is divided into upper and lower molds.
FIG. ₁ is a vertical half-sectional view of a state in which it is placed in a cavity C inside ₁ and a lower mold M ₂ and closed, and shows a state before pouring molten copper from a gate Ma provided on an upper mold M ₁ . .
(C) In the figure, after the copper is solidified by performing this injection, the upper / lower molds M ₁ / M ₂ (showing a sectional view) are separated and the outer cylindrical member 2 (showing a perspective view) as a cast product is shown. Shows the state of being taken out. The upper / lower molds M ₁ / M ₂ are provided with respective cavities C ₁ / C ₂ forming a cavity C corresponding to the outer shape of the outer cylindrical member 2 including the cathode when both sides are closed,
Further, the cathode portion of the lower mold M ₂ is configured such that the outer peripheral portion of the ring-shaped member W projects by a small dimension 1 from the inner surface of the cylindrical portion of the cavity C ₂ .

The product integrally cast in the state shown in FIG.
As shown in FIG. 2, during cooling, the cathode ring W is integrally cast into the inner circumferential groove 2a of the outer cylindrical member 2, and due to the large thermal contraction of Cu, the cathode ring W mainly composed of tungsten is It fits very tightly, and good electrical and thermal conductivity can be expected. During operation, the temperature of the tip of the cathode drops and the generation of powder reduces wear, resulting in long life.

[0013]

As described above, according to the structure and manufacturing method of the present invention, the outer cylindrical member of this type of electrothermal converter and the cathode electrode of the tungsten alloy have extremely good electrical and thermal conductivity. As a result, a stable discharge state can be obtained, and a long-life cathode with very little wear can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a method of manufacturing an outer cylindrical member with a cathode.

FIG. 2 is a vertical half sectional view of an outer cylindrical member manufactured by this method.

[Fig. 3] Schematic configuration diagram of an electrothermal converter

FIG. 4 is a diagram corresponding to FIG. 2 according to the conventional method.

[Explanation of symbols]

1/2 in / outer cylindrical member 2a circumferential grooves 3 periphery container 9/4/10 first / second / third space 5/6 +/- discharge electrodes C, C _1, C ₂ cavity M ₁ / M ₂ Upper / Lower type W Tungsten alloy ring-shaped member

Claims (2)

[Claims] 1. A first, a second and a third space are sequentially formed from the inside by the inner and outer double cylindrical members and the outer peripheral container arranged concentrically, and the first and the third spaces are formed. In an electrothermal converter configured to flow a fluid to be heated, apply a DC voltage to the second space to form arc plasma, and generate heat to heat the fluid to be heated, the outer cylindrical member is discharged. The cathode side and the inner cylindrical member are used as the discharge anode side, and for the cathode, the outer cylindrical member made of copper is buried so as to be exposed in a circumferential groove formed on the inner surface of the outer cylindrical member. An electrothermal converter having a ring-shaped member made of tungsten alloy. 2. The inner, outer double cylindrical member and its outer peripheral container arranged concentrically form first, second and third spaces in order from the inside, respectively. A discharge cathode of an electrothermal converter configured to flow a fluid to be heated and apply a DC voltage to the second space to form arc plasma, and heat the fluid to be heated by the generated heat. As a method for manufacturing the outer cylindrical member, using a vertical split mold for casting having a cavity corresponding to the outer shape of the outer cylindrical member in a state where a rectangular cross-section ring-shaped cathode member is provided on the inner circumferential surface thereof, A ring-shaped member made of tungsten alloy as the produced cathode,
Inserting molten copper through the injection hole formed at the top of the cavity after interposing the outer peripheral portion between the upper and lower divided molds so as to project from the inner surface of the cylindrical portion of the cavity to close both molds. A method for manufacturing an electrothermal converter, characterized in that it is configured to be cast by.