JPH06100340B2 - Self-regulating ceramic glow plug - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rapid heating type ceramic glow plug which is mounted in a precombustion chamber of a diesel engine and is used for preheating the cylinder or the precombustion chamber at the time of starting.

Problems to be Solved by the Prior Art and Invention: The conventional self-controlled ceramic glow plugs are described in Japanese Utility Model Publication No. 61-13165 and Japanese Patent Publication No. 61-13613, which are illustrated in FIG. Things are known. As shown in the order of FIGS. 6 to 9, the outer cylinder 22 and the lead coil 23 are brazed to the ceramic heating element 2 at the same time, and after that, the outer cylinder end portion is first brazed to the inner cavity of the fitting 1. After removing the excess silver braze 24 in the lead coil 23, the sheath resistor 11 is welded, and the oxide film on the surface of the outer cylinder 22 is removed.
Braze 25 into the bore of the mounting bracket. Therefore, there are problems that the number of parts is large, the structure is complicated, and the manufacturing cost is increased, and the elasticity of the lead coil itself makes the relative positions of the dimensions unstable, which is not suitable for mass production.

Means and Embodiments for Solving Problems: FIG. 1 is a longitudinal sectional view of a self-regulating ceramic glow plug of the present invention, in which 1 is a mounting bracket, 2 is a ceramic heating element, and 11 is a sheath. Resistor, 20 indicates the center axis, seed resistor
11 is the packing of heat-resistant insulator on the end face of the metal tube 12
The packing 14 serves as a packing member for the mounting fitting bore 4 provided with the insulating layer 27 when the packing 14 is held. This packing 14
A lead electrode 13 is attached to this, and communicates with the center shaft 20 by a resistor coil 15, and the other end is exposed and faces the ceramic heating element 2. A heating wire is embedded in the ceramic heating element 2, and the former of the lead wires 5 and 7 has its end portion 6 bare on the side surface of the ceramic heating element 2 and is connected to the mounting member 1 by brazing and the other end The end portion 8 of the lead wire 7 is barely exposed to the head 9 of the ceramic heating element 2 protruding into the inner cavity 4. A conductive sealing material 10 is sealed in an inner space 4 between the packing 14 and the head 9 through an insulating layer 27. As the conductive sealing material 10, a metal powder and a glass powder, or a material obtained by mixing these with conductive ceramic powder is used. The conductive sealing material 10 ensures electrical continuity with the lead electrode 13. Unlike the conventional example in which the metal heating element is brazed to the mounting bracket, the ceramic heating element 2 is directly mounted on the mounting bracket 1.
It is brazed 21 to the small diameter portion 3 of. Therefore, the length of the ceramic heating element 2 protruding from the end surface of the mounting member 1 toward the combustion chamber is always fixed, and a stable dimension and positional relationship can be obtained. As described above, the end portion 6 which is embedded in the ceramic heating element and serves as one electrode of the lead wire is exposed on the side surface and is electrically connected to the fitting 1 by the brazing 21 as shown in FIG. In this state, the conductive seal material 10 is enclosed, and the sheath resistor 11 is inserted from above as shown in FIG. 3, heated in an electric furnace and pressed by a press 26 through an insulating seal material 17. . The powdery conductive sealing material 10 enclosed by the packing 14 is heated and pressurized in the inner cavity 4 provided with the insulating layer 27, and as shown in FIG. 4, the lead electrode 13 and the head portion 9 of the ceramic heating element 2. It is sealed together with.

Actions and effects: The self-controlling ceramic glow plug of the present invention has the above-mentioned configuration, and the lead electrode is exposed by using the conductive sealing material for the conduction between the sheath resistor and the ceramic heating element without using the lead coil. The packing seals the end face of the sheath resistor and the insulating layer seals the internal cavity that prevents short-circuiting to the mounting bracket, while the structure is the first to braze the ceramic heating element and the small diameter part of the mounting bracket. Since the two are directly connected so that a certain length of the two protrudes from the end face of the latter, the dimensional relationship and the positional relationship of the both are surely kept constant, and a stable product suitable for mass production can be obtained. In addition, since a metal outer cylinder is not used, it is not necessary to remove excess silver brazing due to brazing with the lead coil or to remove oxide film on the metal outer cylindrical surface when brazing with the small diameter part of the mounting bracket. Therefore, the manufacturing process is remarkably simplified.
Therefore, it is possible to greatly reduce the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a self-regulating ceramic glow plug of the present invention, and FIG. 2 is a vertical sectional front view showing a brazing connection state of a mounting bracket and a ceramic heating element as a first step of manufacturing, and FIG. As a next stage, a vertical sectional front view of a state immediately before pressurizing the insulating seal member of the mounting bracket accommodating each part,
FIG. 4 is a vertical sectional front view in a pressure-sealed state, FIG. 5 is a vertical sectional front view of a conventional self-controlled ceramic glow plug using a lead coil, and FIGS. FIG. DESCRIPTION OF SYMBOLS 1 ... Mounting bracket, 2 ... Ceramic heating element, 3 ... Small lumen diameter part, 4 ... Lumen, 5,7 ... Lead wire, 6,8 ... Lead wire end part, 9
… Ceramic heating element head, 10… Conductive sealing material, 11… Sheath resistor, 12… Metal tube, 13… Lead electrode, 14…
Packing, 15 ... Resistor coil, 16 ... Filling powder, 17 ... Insulating sealing material, 18 ... Insulator, 19 ... Nut, 20 ... Center rod, 21 ... Brazing, 26 ... Press, 27 ... Insulating layer

Claims (1)

[Claims] 1. A sheathed resistor, in which a resistor coil connected in series with a ceramic heating element is insulated and embedded in a metal tube together with a center electrode of a terminal and a lead electrode for the ceramic heating element, is fitted in an inner cavity of a mounting member. In the self-regulating ceramic glow plug, a heat-resistant insulator closed so that the tip of the lead electrode 13 is exposed is provided on the end surface of the metal tube 12 of the sheath resistor 11, and at the same time, an insulating layer provided in the inner cavity 4 is provided. As a packing 14 for 27, a ceramic heating element and one end 6 of the lead wire 5 exposed on the side surface of the ceramic heating element are joined to the tip small diameter portion 3 of the inner cavity,
A conductive sealing material 10 is sealed in the mounting member inner cavity 4 between the packing 14 and the end portion 8 of the other lead wire 7 and the ceramic heating element head portion 9 exposed on the side surface. Self-regulating ceramic glow plug consisting of.