JPS6086325A - Self-control type ceramic glow plug - Google Patents

Abstract

PURPOSE:To improve durability and facilitate assembling by a method wherein the rear end opening of a mounting fitment is fixed to and integrated with the mounting fitment shielding it perfectly from atmosphere by glass seal. CONSTITUTION:A connection constituting section, including the coil 7 of resistance body, a center shaft 8 and a part of a lead electrode shaft 6, is covered by a metallic tube 12 and buried into heat insulating member 13 such as the powder of magnesia or the like for example filling the cavity of the metallic tube to secure it to the member 13. The sleeve 14 of a metal or ceramic is inserted into the rear end of the metallic tube 12, a part 14a of the sleeve 14 is projected from the rear end face of the metallic tube 12 and is arranged so as to cover the center shaft 8 while the rear end of the metallic tube 12 and the center shaft 8 are sealed with glass seal 15 and integrated in the cavity of the sleeve 8 to form them as a center shaft assembly 16. According to this method, the ceramic glow plug, excellent in durability and easy in assembling, may be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a self-control type glow plug that is installed in a diesel engine and preheats an auxiliary combustion chamber and the like during startup.

In general, diesel engines have poor starting performance at low temperatures, so a method is to install a glow plug in the auxiliary combustion chamber, turn it on, make it red hot, and burn part of the fuel injected into the room to preheat it. In addition to being required to have a rapid temperature rise characteristic at the time of starting, there is a recent trend of using 77 Targlow for a long time to stabilize combustion even after starting. There is an increasing need for improved durability.

As a rapid heating type glow plug suitable for this purpose, a ceramic heater made by embedding a heating wire of a high melting point metal in ceramic powder and sintering it is used as the heating element, and the heating wire is fused when the temperature rises rapidly. Alternatively, in order to prevent ceramic cracking due to thermal shock, a resistor using a wire material with a positive temperature coefficient of resistance greater than 1 heating wire is connected in series to the heating element to control the heating current of the heating element. A self-regulating ceramic glow plug with a similar structure is known.

Fig. 1 shows a conventional example of this type of glow plug.
is embedded in a ceramic sintered body and soldered to the inner cavity of the formed metal outer cylinder 3, and one end 2a of the heating wire 2 is electrically connected. The e-side electrode is formed by soldering to the electrode. On the other hand, the other end 2b of the heating wire 2 is soldered to a metal cap 5 fitted to the rear end of the ceramic heater 1, and electrically connected to the resistor coil 7 via a lead electrode shaft 6 welded to the cap 5. The other end of the resistor coil 7 is connected to the tip of the center shaft 8.

The connection component between the ceramic heater 1, the resistor coil T, and the center shaft 8 in the inner cavity of the mounting bracket 4 is sealed by heating by filling the inner cavity with glass powder 9. This has a structure in which the rear end of the mounting bracket 4 is tightened and fixed with a round nut 11 with an insulator 10 interposed therebetween, and serves as a terminal electrode on the ■ side.

In the conventional self-regulating ceramic globe 2, which has such a structure, the temperature of the resistor increases due to the difference in temperature coefficient of resistance between the wire of the resistor and the wire of the heat-generating wire when electricity is applied and the temperature rises. The line increases rapidly.

Along with this, the resistance value increases, which reduces the heating current of the heating wire and prevents the heating element from overheating. 7, the center shaft 8, and the ceramic heater 1 are sealed in the inner cavity of the mounting bracket 4 with glass. ) There was a problem in that the glass broke and the sealing properties were impaired, and outside air entered through the broken part, promoting oxidation of the resistor coil T and reducing its durability.

The present invention aims to provide a self-regulating ceramic glow plug that solves the above-mentioned problems, has improved durability, and is easy to assemble.

The present invention will be explained in detail below with reference to the drawings.

FIG. 2 is a longitudinal cross-sectional view of an embodiment showing the main structure of a self-regulating ceramic globe 2 according to the present invention, and the same parts as in FIG. 1 are designated by the same reference numerals.

In the figure, 7 is a resistor coil made of nickel or iron (F), which has a large temperature coefficient of resistance, and one end of which protrudes from the rear end of the mounting bracket 4 to become the ■ side terminal electrode. It is connected to the tip 8a of the center shaft 8, and the other end is connected to a ceramic heater using a wire having a smaller temperature coefficient of resistance than the wire of the resistor coil, for example, a W alloy made of tungsten (W) and rhenium (R). (connected to the lead electrode shaft 6 which is connected to the heating wire (omitted and not shown in FIG. 2)), the resistor coil 7, the center shaft 8 and the lead electrode shaft 6.
The connection component including a part of the metal tube 12 is covered with a metal tube 12, and is embedded and fixed in a heat-resistant insulating material 13, such as magnesia powder, filled in the inner cavity of the metal tube 12. A metal or ceramic sleeve 14 is inserted into the metal tube 1, and a portion 14a of the metal or ceramic sleeve 14 is inserted into the metal tube 1.
2 is arranged so as to protrude from the rear end surface of the central shaft 8 and cover the central shaft 8,
A center shaft assembly 1 in which the rear end of the metal chip 12 and the center shaft 8 are integrated with a glass seal 15 within the inner cavity of the sleeve 14.
The center shaft assembly 16 is inserted into the bore of the fitting A4 from the rear end opening of the sleeve 14.
The distal end surface of the crotch seat 4a in the inner cavity is held in contact with the crotch seat 4a, and its free end curve is crimped with the rear end opening edge 4b of the mounting bracket 4, and the center shaft assembly 16 is inserted into the inner cavity of the mounting bracket 4. It has a fixed structure.

As shown in FIG. 5 (the same parts as in FIG. 2 are denoted by the same reference numerals), the center shaft assembly 16 described above is made by injecting magnesia or the like into the internal space of the resistor coil 7 connected to the center shaft 8 and the lead electrode shaft 6. Six bodies 13-1 preformed with heat-resistant insulating powder are inserted, and a preformed tube 131 made of the same material as the six bodies 13-1 is inserted outside the connection component including a part of the center shaft 8 and lead electrode shaft 6. Insert this into the metal tube 17.
The resistor coil 7 and the center shaft 8 are assembled as shown in FIG.
After forming a molded body by embedding and fixing the connection components including a part of the lead electrode shaft 6 in the heat-resistant insulating material 13 in the metal tube 12, the metal tube 12 of the molded body is assembled as shown in FIG. A metal or ceramic sleeve 14 is inserted on the outside of the rear end, and a part 14a of the sleeve 14 is arranged so as to protrude from the rear end surface of the metal tube 12, so that there is a gap between the inner surface of the sleeve 14 and the metal tube 12. Insert the glass pipe 15-1 into the metal tube 12, fill the gap between the glass pipe 15-1 and the center shaft 8 with glass powder 15-8, heat it in a N atmosphere, and insert the glass powder 15-8 into the rear end of the metal tube 12 and the center shaft 8. is glass-sealed within the lumen of the sleeve 14.

It is obtained as an integrated structure.

In the glass sealing process, the glass pipe inserted between the inner surface of the sleeve 14 and the outer part of the metal tube 12 is omitted, and after the metal tube 12 is directly ultrasonically press-fitted or soldered to the sleeve 14, the sleeve 14 is The glass powder 15-1 may be filled into the inner cavity and heated to form the glass seal 15.

The rest of the structure of the self-control type plug in this embodiment is the same as that of the conventional example shown in FIG. 1, so a description thereof will be omitted.

As can be understood from the above description, in the self-regulating glow plug of the present invention, the resistor coil in the lumen of the mounting bracket is connected to the center shaft and the heating element in the heat-resistant insulating material filled in the lumen of the metal tube. It has a sheathed heater structure that is buried and covered, including the connection part, and the opening side of the rear end of the mounting bracket is completely isolated from the outside air by a glass cooler and is integrated into a structure that is fixed to the mounting bracket. As a result, it is extremely strong, has excellent durability, and has a self-control function to prevent the heating element from overheating, and can be provided as a ceramic glow plug that solves the problems of conventional products.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing a conventional example of a self-controlling ceramic glow plug, FIG. 2 is a longitudinal cross-sectional view of an embodiment showing main parts of the self-controlling ceramic glow plug of the present invention, and FIG.
Embodiment of the present invention (This is an explanatory diagram of the manufacturing procedure of the center shaft assembly in 2. 1: Ceramic heater, 2: Heat generating wire, 3: Metal outer fl
N, 4: Mounting bracket, 4a: JR seat, 4b: rA opening periphery, 5: Cap, 6: Lead electrode shaft, 7: Resistor coil, 8: Center shaft, 9.13: Heat-resistant insulation material, 10: Insulation body, 1
1: Round nut, 12: Metal chip, 14 Ni sleeve,
15 Nigarasu seal, 16: Central shaft assembly. Agent Patent Attorney Mamoru Takeuchi 1E Figure 3 (A) (B) (C)

Claims (1)

[Claims] A self-control glow plug, in which a current control resistor is connected in series within the inner cavity of the fitting to a heating element provided at the tip of the fitting in order to control the temperature of the heating element when energized and the temperature rises. Odor 'C1 As a heating element provided at the tip of the mounting bracket, a ceramic heater made by embedding a heating wire in ceramic powder and sintering the ceramic heater is used.
A resistor coil connected to the metal tube is arranged in a metal tube with both ends open, one end of which is connected to a center shaft that protrudes from the rear end of the metal tube and serves as a terminal electrode, and the other end is connected to a heater. 9. The connection component within the metal tube is embedded and fixed in a heat-resistant insulating material filled in the inner cavity. Furthermore, a sleeve is inserted into the rear end of the metal tube, and a part of the sleeve protrudes from the rear end surface of the metal tube to cover a part of the center shaft, and the inner surface of the sleeve and the metal tube and the outer periphery of the center shaft are filled with glass powder and heat-sealed to form an integrated center shaft assembly, and the assembly is inserted into the inner cavity of the mounting bracket from the rear end opening, and A self-controlling ceramic hip plug characterized by having a structure in which the distal end surface of the sleeve abuts and locks against the crotch seat in the inner cavity, and the free end of the sleeve is crimped and fixed around the rear end of the mounting bracket. .