JPS61149726A - Ceramic glow plug - Google Patents

Abstract

PURPOSE:To protect an electrode extending part in a ceramic glow plug to be installed in an engine by a method wherein the electrode extending part and a brazing connected part are separated to each other and the electrode extending part is specifically sealed. CONSTITUTION:A connection metallic cyliner 6 is arranged at an outer circumference part near the extremity end of an intermediate part of a ceramic heater body 1 and the ceramic heater body 1 is inserted and fitted to the metallic outer cylinder 7. A cathode fitting 8 is arranged in a clearance between the metallic outer cylinder 7 and the ceramic heater body 1 in such a way as it may be contacted with the exposed part 4a of the cathode extending line 4. The cathode metal 8 and the anode fitting 5 are covered with a seal member 9. The seal member 9 covers integrally the cathode electrode fitting 8 and the anode fitting 5. It is also possible to make a separate sealing of the cathode fitting 8 and the anode fitting 5, respectively. After the ceramic heater body 1, connection metallic cylinder 6, cathode fitting 8 and anode fitting 5 are brazed at 800-950 deg.C, various seals are applied to them. That is, glass seal is applied at a temperature range of 900-1,100 deg.C, heat-resistant epoxy rsin (thermo-setting) is applied at a temperature of 200 deg.C and an alumina heat-resistant adhesive agent or the like is applied at a temperature of 200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention primarily relates to a ceramic glow plug installed in a diesel engine.

"Prior Art" Conventionally, this type of ceramic glow plug, as shown in FIG. 4, has a heating wire 102 embedded in the tip side of a rod-shaped ceramic heating element 101, and positive electrodes are taken out at both ends of the heating wire 102. Connect the wire 103 and the negative electrode lead wire 104, and connect the other end of the positive electrode lead wire 103 to the ceramic heating element 1.
01 and connected to the anode fitting 105, and the other end of the negative electrode lead wire 104 is connected to the exposed portion 106 of the negative electrode lead wire 104 on the outer periphery of the intermediate portion of the ceramic heating element 101.
The ceramic heating element 101 is fitted into the metal outer cylinder 108 with the cathode metal body 107 interposed so as to be in contact with the metal outer cylinder 108.

"Problems to be Solved by the Invention" The cathode metal cylinder 107 of this ceramic glow plug is
Connecting the electrode portion by contacting the exposed portion 106 of the cathode lead wire 104, and connecting the ceramic heating element 101 and the metal outer cylinder 1G.
It functions as a bond with B.

When the cathode metal cylindrical body 107 is made to perform both functions in this way, each time this glow plug is subjected to thermal history, a clearance is generated between the ceramic and the metal due to the difference in thermal expansion coefficient between the ceramic and the metal. The seal of the ceramic glow plug is weakened, and problems are likely to occur in connection with the exposed portion 106 of the negative electrode lead wire 104.

It has been reported that when glass is baked onto a ceramic surface, the surface is foamed, and then silver solder is poured into the ceramic surface, there is little loss in sealing strength and strength even at 300°C.
This is not necessarily sufficient under severe conditions such as engines that undergo frequent thermal cycles.

"Means and Actions for Solving the Problems" The electrode lead-out part and the solder are separated from the joint part, and the electrode lead-out part is specially sealed to protect the electrode lead-out part.

"Example" As shown in Fig. 1, a heating wire 2 is buried in the tip side of a rod-shaped ceramic heating element 1, and a positive electrode lead wire 3 and a negative electrode lead wire 4 are connected to both ends of the heat generating wire 2, respectively. The other end of the positive electrode lead wire 3 is exposed to the base end side of the ceramic heating element 1 and connected to the positive electrode 5, and the other end of the negative electrode lead wire 3 is exposed to the intermediate part of the ceramic heat generating element 1.

On the outer periphery of the intermediate portion of the ceramic heating element 1 near the tip,
A ceramic heating element 1 is fitted into a metal outer cylinder 7 with a connecting metal cylinder 6 interposed therebetween.

The negative electrode is taken out in the gap between the metal outer cylinder 7 and the ceramic heating element 1! ! The cathode metal fitting 8 is arranged so as to contact the exposed portion 4a of I4, and the cathode metal fitting 8 and the anode metal fitting 5 are covered with a sealing material 9. Although an example is shown in which the sealing material 9 integrally covers the cathode metal fitting 8 and the anode metal fitting 5, the cathode metal fitting 8 and the anode metal fitting 5 can also be sealed separately.

After the ceramic heating element 1, the connecting metal cylinder 6, the cathode fitting 8 and the anode fitting 5 were brazed at 800 to -950°C, various seals were applied.

That is, a glass seal was used at 900 to 1100°C, a heat-resistant epoxy resin (thermosetting) was used at 200°C, and an alumina-based ceramic heat-resistant adhesive was used at 200°C.

The results were as follows, and the samples were immersed in a fluorescent flaw detection solution at 85° C. for 24 hours and determined by whether or not the sample had penetrated into the electrode extraction portion.

Number of penetrants/number of samples Conventional (without sticker) 9150 glass 2.4 xlO/ ``c (BO-3iO-CaO system') 01506.4 xlO/ ``C (ZnO-
SiO-BaO system) 2150 heat-resistant epoxy resin (thermosetting) 015G alumina-based ceramic heat-resistant adhesive 3150 silicone resin
0150 silicone rubber 0
150 Tarpitz 0150
The ceramic glow plug shown in FIG. 2 has a cathode metal fitting 12 formed by connecting a disk part 10 and a cylindrical part 11 shown in FIG. The disk portion 10 is brought into contact with the opposing end surface of the connecting metal cylinder 6.
The connecting metal cylinder 6 and the cathode metal fitting 12 are connected to the lead wire 13 by fitting and fixing them onto the ceramic heating element l at a distance of at least 100 cm.
Connect with.

800-1100℃ with glass with linear expansion coefficient 3-7X1G
Seal by baking or curing a heat-resistant sealant such as heat-resistant epoxy resin, ceramic heat-resistant adhesive, silicone rubber, etc.

``Effects of the Invention'' As described above, the present invention has conventionally had the function of not only connecting the ceramic heating element and the metal outer cylinder but also taking out the electrode using the cathode cylinder. Because the connection is made with the connecting metal cylinder, the electrode extraction part is separated, and it is covered with a sealing material to protect it, the seal between the ceramic heating element and the connecting metal cylinder is broken. However, since there is a seal between the cathode metal fitting and the anode metal fitting, the insulation of the electrode extraction part will not be destroyed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a specific embodiment of the present invention, FIG. 2 is a longitudinal sectional view of another embodiment of the invention, FIG. 3 is a perspective view of a cathode fitting, and FIG. 4 is a conventional example. FIG.

Claims (1)

[Claims] (1) A heating wire is embedded in the tip side of a rod-shaped ceramic heating element, a positive electrode lead wire and a negative electrode lead wire are connected to both ends of the heat generating wire, respectively, and the other end of the positive electrode lead wire is connected to the base of the ceramic heating element. The end side is exposed and connected to the anode metal fitting, the other end of the negative electrode lead wire is exposed at the intermediate part of the ceramic heating element, and a connecting metal cylinder is interposed on the outer periphery of the intermediate part of the ceramic heating element near the tip. In a ceramic glow plug in which a ceramic heating element is fitted into a metal outer cylinder, a cathode fitting is arranged in the gap between the metal outer cylinder and the ceramic heating element so as to contact the exposed part of the cathode lead wire, and the cathode fitting and Ceramic glow plug characterized by having an anode fitting covered with a sealing material (2) A heating wire is embedded in the tip side of a rod-shaped ceramic heating element, and a positive electrode lead wire and a negative electrode lead wire are provided at both ends of the heat generating wire, respectively. The other end of the anode lead wire is exposed to the base end side of the ceramic heating element and connected to the anode metal fitting, and the other end of the cathode lead wire is exposed to the middle part of the ceramic heat generating element. In a ceramic glow plug in which a ceramic heating element is fitted into a metal outer cylinder with a connecting metal cylinder interposed on the outer periphery of the middle part of the body near the tip, the cathode lead wire is inserted into the gap between the metal outer cylinder and the ceramic heating element. A ceramic glow plug characterized in that a cathode metal fitting is placed in contact with an exposed portion of the metal tube and separated from the connecting metal cylinder, and the cathode metal fitting and the connecting metal cylinder are connected by a lead wire.