JPH0335787B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ring-shaped heater in which a heating wire is embedded in a ring-shaped ceramic body, and a method for manufacturing the same.

[Prior Art] Ceramic heaters that have been widely used in various fields are generally those that have a heating pattern formed by printing methods built into the ceramic body, or those that have a flat plate or cylindrical shape with a heating wire embedded in them. It is true. These flat or pipe-shaped ceramic heaters are relatively large and simple, so it was not difficult to attach the current-carrying lead wires by brazing or other methods. .

On the other hand, due to the excellent characteristics of ceramic heaters, their applications are becoming more widespread. When installed in the swirl chamber of a type diesel engine to improve startability and performance during operation, it should be adapted to the circular shape of the intake pipe and swirl chamber to improve heating efficiency, ease of installation, etc. It is desirable that the shape of the ceramic heater used for heating is ring-shaped. In addition, even when heating water, oil, etc. in a transfer pipe, a ring-shaped heater is extremely convenient because it has low flow resistance and can heat efficiently.

[Problem to be solved by the invention] However, with ring-shaped heaters, there are difficulties in the work of attaching the lead electrodes for energization and the structure of the lead electrodes, so it has been difficult to develop a small-shaped ring heater with high heat generation density with high productivity. Because they cannot be manufactured and are expensive, they have not been widely used despite their high utility value.

[Object of the Invention] In view of the above, it is an object of the present invention to provide a ring-shaped heater that has a simple mounting structure for lead electrodes for energization and is easy to manufacture, and a method for manufacturing the same.

[Means for Solving the Problems] The ring-shaped heater of the present invention has a heating element and electrode wires connected to both ends thereof embedded in a ring-shaped ceramic body, and the electrode wires are connected to both end surfaces of the ring-shaped ceramic body. A metallized layer is exposed on each end face, and a plating film is formed on the metallized layer to form an external lead-out electrode. a step of firing a ring-shaped ceramic body in which an electrode wire is embedded; a step of slicing both ends of the ring-shaped ceramic body into rings to expose a part of the electrode wire on the cut surface; and a step of making the cut surface conductive with the electrode wire. This method is characterized by the step of forming a metallized layer and then applying a plating film.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. 1st
The figure shows the material (semi-finished product) of a ring-shaped heater.
The heating wire 2 is embedded in a coiled wire made of high-melting point metal such as tungsten or molybdenum, and the ceramic body 1 is made of alumina ceramic, silicon nitride with high thermal shock resistance, etc. Sialon or the like is used, but the heat-generating wire 2 is set in advance in a predetermined mold body, and the ceramic raw material powder as described above is filled and molded, which is then obtained by firing in an atmosphere or by hot pressing. It is. In addition, heating wire 2
Both ends of the electrode wire 3 are wound around and electrically connected to one end of an electrode wire 3 made of a tungsten wire having a wire diameter larger than that of the heating wire 2, and the other end of the electrode wire 3 is shown in FIGS. 1A and a. It's wrapped in layers, like this. The ceramic body 1, in which the heating wire 2 and the electrode wire 3 connected thereto are embedded and built in, is cut into circular slices at the positions of the Y-Y line and the Y'-Y' line in FIG. 1a. In the upper and lower cut surfaces 1a and 1b formed as shown in FIGS. 2B and 2B, as is clear from FIG.
It is exposed so as to form the same plane as the lower surface. A metallization paste is applied to the cut surfaces 1a, 1b as shown in FIG. Form layers 4a and 4b. Furthermore, in order to improve the electrical conductivity of the metallized layers 4a and 4b, plating films 5a and 5b of copper, nickel, silver, etc. are applied to the metallized layers 4a and 4b on both end faces within the ceramic body 1. , 4b and a lead electrode made of a plating film attached thereto, a ring-shaped heater H as shown in FIG. 4 is manufactured.

[Effects of the Invention] According to the manufacturing process described above, lead electrodes for energization can be easily and reliably attached to both end faces. In addition, since it is ring-shaped and has lead electrodes on both ends, it is easy to wire the current, and it can be placed in the middle of the pipe, so that the liquid, gas, etc. It is possible to provide a ring-shaped heater that can be used in a wide range of applications and has high utility value, such as being able to heat efficiently without requiring much space.

[Brief explanation of the drawing]

1A, 2B, and 3C are plan views for explaining the manufacturing process of a ring-shaped heater according to the present invention, and FIGS. A, X-X in each of Figure 2B and Figure 3C
FIGS. 4D and 4D are a cross-sectional view showing a plane of the ring-shaped heater according to the present invention, and a cross-sectional view taken along line X--X in FIG. 4D, respectively. 1: ceramic body, 2: heating wire, 3: electrode wire,
4a, 4b: metallized layer, 5a, 5b: plating film, H: ring-shaped heater.

Claims (1)

[Claims] 1. A heating wire and electrode wires connected to both ends of the heating wire are buried in a ring-shaped ceramic body, and a part of the electrode wire is exposed on both end surfaces of the ring-shaped ceramic body. A ring-shaped heater characterized in that a metallized layer is formed on each end face, and a plating film is formed on the metallized layer to serve as an external lead-out electrode. 2. A step of firing a ring-shaped ceramic body in which a heating wire and electrode wires connected to both ends of the heating wire are embedded, and cutting both ends of the ring-shaped ceramic body into rings and inserting the electrode wires on the cut surface. A method for manufacturing a ring-shaped heater comprising the steps of: exposing a portion of each ring-shaped heater; and forming a metallized layer conductive to the electrode wire on the cut surface, and then applying a plating film.