JP2000121055A - Ceramic heater type glow plug and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure reliable electrical connection without increasing the occupation space or the radial dimensions of an electrode take-out structure on the rear end side of a ceramic heater at the time of elongating a ceramic heater type glow plug while decreasing the diameter. SOLUTION: End part 15b of one lead part 15 from a heating element 13 is connected electrically with one end 18a of an electrode take-out metal 18 in a ceramic heating element (ceramic heater) 11. In order to make the electrical connection, a connector 17 of ceramics molding or sintered ceramics is buried in the rear end part of the ceramic heating element. One end 18a of the electrode take-out metal is inserted into the electrode take-out metal insertion hole 17b of the connector 17 and the other end thereof is extended rearward from the rear end face of the ceramic heating element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature ceramic heater type glow plug used for assisting starting of a diesel engine, and more particularly to a direct-injection multi-valve diesel engine in order to comply with exhaust gas regulations. In addition to improving the structure of taking out the electrodes from the ceramic heating element (ceramic heater), the small-diameter portion on the tip side of the glow plug is extended in the axial direction to form a long length, and the whole including the tip side The present invention relates to a ceramic heater type glow plug having a reduced diameter and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a glow plug used for assisting starting of a diesel engine, in order to comply with recent long-term exhaust gas regulations, the peak temperature reaching time is increased, the peak temperature and the saturation temperature are increased, and the after-glow time is extended. The need is emerging. In order to meet these demands, the heating element needs to be made of a high melting point metal material or an inorganic conductive material, and the small diameter portion has been changed from a metal material to a ceramic which can be used at a high temperature. .

[0003] For example, Japanese Patent Publication No. Sho 62-19034 discloses that a high melting point metal material such as W (tungsten) is resistant to oxidation.
A ceramic heater type glow plug using a ceramic heater embedded in ceramics such as silicon nitride having excellent thermal shock resistance has been proposed.

Further, as part of the response to the exhaust gas regulations described above, the combustion system of a diesel engine has shifted from a type having an auxiliary combustion chamber to a direct injection type, that is, a so-called direct injection type. Is coming. Accordingly, a glow plug for improving the startability of the engine at low temperatures is also attached to the cylinder head together with the fuel injection nozzle. The front end of the heater faces the main combustion chamber, and the interior of the main combustion chamber is preheated to serve as an auxiliary ignition source.

[0005] The glow plug used in such a direct injection type diesel engine passes through the wall of the cylinder head and faces the main combustion chamber, so that the overall length is longer and thinner than the type in which the sub-combustion chamber is preheated. It is necessary to form to the diameter. That is, many supply and exhaust valves are provided on the cylinder head to which such a glow plug is attached,
Also, it is necessary to maximize the area of the valve port.

Further, in order to secure the strength of the cylinder head, it is necessary to increase the thickness of the cylinder head.
For this reason, the insertion opening for mounting the glow plug has become very thin and long, and accordingly, the glow plug also needs to be formed very long.

Therefore, in the above-described ceramic heater type glow plug, measures have been taken to reduce the diameter of the ceramic heater, the metal outer cylinder holding the same, the tubular housing, and the like as much as possible and to increase the overall length. It is being taken.

[0008]

However, when the small diameter portion on the tip side of the glow plug is entirely made of ceramics as described above, the ceramic portion is attached to the glow plug by the force applied when the glow plug is attached to the cylinder head or pulled out. May be damaged, which is a problem in strength. Therefore,
It is practically difficult to form the above-described small-diameter portion long using only a ceramic heater made of ceramics.

That is, in a glow plug using such a ceramic heater, the screw diameter of the glow plug in the tubular housing is actually changed from M10 to M10, for example.
As shown in FIG. 8, the tubular housing has been made as thin as possible.
On the other hand, in the conventional ceramic heater-type glow plug, the ceramic heater serving as the heat generating portion has a problem in strength as described above, and therefore has a diameter dimension larger than that of the current ceramic heater (all are 3.4 mmφ or more). It is difficult to make it thin. This ensures sufficient strength against external forces,
This is unavoidable due to the restriction of maintaining the amount of protrusion into the combustion chamber described above.

For this reason, in the ceramic heater type glow plug, when the diameter of the tubular housing or the metal outer cylinder is reduced as described above, the conventional electrode is not used because of the space on the ceramic heater side and the electrical connection. There was a problem that the take-out structure could not be adopted.

That is, not only the problem that the strength is reduced when the diameter of the tubular housing is reduced, but also the diameter of the ceramic heater does not change, so that the metal wire is exposed at the end of the conventional heater element, and the terminal is connected to the metal wire. In a structure in which a cap is brazed (Japanese Utility Model Publication No. 60-30608) or a structure in which a spirally wound metal wire is fixed by brazing or the like (Japanese Patent Application Laid-Open No. 60-114463), a gap between the tubular housing and the housing is required. However, it was impossible to take out the electrodes both spatially and electrically because of the small size.

Japanese Patent Application Laid-Open No. 62-295382 discloses that the end of a lead portion of a heating element is spirally wound, an insertion hole is formed in the end portion, and an electrode extraction metal fitting is brazed to the insertion hole. Shows a structure electrically connected by the above. However, in such a structure, it is impossible to form a state in which the lead portion is wound in the ceramic if the portion made of the insulating ceramic is as thin as, for example, about 3.5 mmφ. Furthermore, it is very difficult to make a hole for inserting the electrode extraction fitting in the part made of ceramics.
There is also a problem that the manufacturing cost increases.

In Japanese Patent Publication No. 2-28044,
It describes a structure in which a step is provided at the rear end of a ceramic heater and joined to a terminal fitting. However, it is very difficult to process a cylindrical ceramic sintered body so as to provide a step, as described above, and the manufacturing cost is high.

The present invention has been made in view of the above circumstances, and has been made to increase the length and diameter of the entire glow plug.
For example, the thread diameter of the threaded portion of the tubular housing is set to M1.
Even if the ceramic heater is made as thin as 0 to M8 and the diameter of the ceramic heater is further reduced to, for example, about 3.5 mmφ, the ceramic heater-type glow plug and the ceramic heater-type glow plug which can easily be electrically connected to the electrode take-out means and have no manufacturing cost The purpose is to obtain a manufacturing method.

Further, the present invention improves the structure on the ceramic heater side, particularly the structure of the electrode take-out portion from the rear end, which has been a problem in the prior art, in order to increase the length and diameter of the entire glow plug. It is another object of the present invention to provide a ceramic heater type glow plug which has a simple structure, is easy to electrically connect, is inexpensive, and can contribute to a reduction in the diameter of the entire glow plug, and a method for manufacturing the same.

[0016]

In order to meet such a demand, a ceramic heater type glow plug according to the present invention (the invention according to claim 1) includes a heating element made of an inorganic conductive material or a high melting point metal material. In a ceramic heater type glow plug including a ceramic heating element embedded in an insulating ceramic and an electrode extraction metal fitting electrically connected to a lead part at one end of the heating element, the lead part is provided inside the ceramic heating element. Is electrically connected to one end of the electrode extraction metal fitting, and the other end of the electrode extraction metal fitting is extended from a rear end surface of the ceramic heating element.

According to the present invention (the first aspect of the present invention), since the connection between the lead portion and the electrode extraction metal fitting is performed inside the ceramic heating element, the size of the ceramic heating element in the radial direction is large. Instead, the glow plug can be reduced in diameter.

In the ceramic heater type glow plug according to the present invention (the second aspect of the present invention), in the first aspect, the other end of the lead portion and one end of the electrode extraction metal fitting may be connected to the ceramic heating element. And electrically connected inside a connector buried at the rear end.

According to the present invention (the second aspect of the present invention), the connector is embedded in ceramic powder, and a ceramic heating element is formed by firing the connector. Can be connected to

In the ceramic heater type glow plug according to the present invention (the third aspect of the present invention), in the first or second aspect, the other end of the lead portion and one end of the electrode extraction metal fitting may be connected to each other. The ceramic heating element is electrically connected at a rear end side at least five times the diameter of the ceramic heating element in the axial direction from the front end of the ceramic heating element.

According to the present invention (the third aspect of the present invention), the electrical connection between the lead portion of the heating element and the electrode extraction metal fitting is affected by the heat of the tip side heating section in the ceramic heating element. Since this is performed on the rear end side, the strength of the ceramic heating element is improved.

Further, in the ceramic heater type glow plug according to the present invention (invention of claim 4), the connector according to claim 2, wherein the connector has an insertion hole of an electrode extraction metal fitting in which a part of the lead portion is exposed. And one end of the electrode take-out fitting is inserted into the insertion hole to be electrically connected to the other end of the lead portion.

According to the present invention (the fourth aspect of the present invention), the presence of the connector embedded in the ceramic powder for forming the ceramic heating element allows the electrical connection between the lead portion and the electrode extraction metal fitting. Connection is ensured.

Further, in the ceramic heater type glow plug according to the present invention (invention of claim 5), in claim 2, the connector is formed of conductive ceramics or a high melting point metal, and The other end and one end of the electrode extraction fitting are electrically connected via the connector.

According to the present invention (the invention as set forth in claim 5), since the connector is formed of conductive ceramics or a high melting point metal, contact between the lead portion and the electrode extraction metal becomes unnecessary. Regardless, a reliable electrical connection state can be ensured.

The ceramic heater type glow plug according to the present invention (the invention according to claim 6) is the ceramic heater type glow plug according to claim 2, 3 or 4, wherein the other end of the lead portion and the electrode extraction metal fitting are provided. One end is electrically connected by joining the end faces or side faces of these lead portions and the electrode extraction metal fittings.

According to the present invention (the invention described in claim 6), since the connection between the lead portion and the electrode extraction metal fitting is performed inside the connector, the electrical connection can be reliably performed. In particular,
When the side surfaces of the respective connection ends are joined, the connection area increases, electrical connection is ensured, and the mechanical strength increases.

Further, in the ceramic heater type glow plug according to the present invention (the invention according to claim 7), the connector according to claim 2, 3, 4, or 6 is a ceramic molded body. Alternatively, it is characterized by being made of a ceramic sintered body.

According to the present invention (the invention according to claim 7), the electrical connection of the connection end between the lead portion and the electrode extraction metal fitting is made by a ceramic molded body or a ceramic sintered body, so that the electrode extraction metal fitting is provided. Is reliably formed, and the bonding state with the ceramic insulator is also ensured.

Further, the method of manufacturing a ceramic heater type glow plug according to the present invention (the invention according to claim 8) is characterized in that a ceramic heating element in which a heating element made of an inorganic conductive material or a high melting point metal material is embedded in ceramic. A method for manufacturing a ceramic heater type glow plug including an electrode extraction metal fitting electrically connected to one end of a lead portion at one end of the heating element, wherein the heating element and at least a part of the lead portion are embedded. Embedded in the ceramic powder with the connector
The ceramic heating element is formed by firing them.

According to the present invention (the invention as set forth in claim 8), the connector is embedded in the ceramic powder and the ceramic heating element for firing it is molded to form an electrode in the ceramic heating element. Connection with the take-out fitting can be made.

Further, in the method of manufacturing a ceramic heater type glow plug according to the present invention (invention of claim 9), the connector according to claim 8, wherein the connector is provided with a member for forming an insertion hole of an electrode extraction metal fitting. The electrode extraction fitting insertion hole is opened to the outside by removing the member for forming the insertion hole of the electrode extraction fitting after molding the ceramic heating element, and burying the electrode heating fixture. .

The present invention (the invention according to claim 10)
The method for manufacturing a ceramic heater type glow plug according to
10. The connector according to claim 9, wherein the connector is formed of a ceramic molded body or a ceramic sintered body, the insertion hole forming member is formed of a high melting point metal, and the insertion hole forming member is melted with an acid after the molding of the ceramic heating element. By so doing, the electrode extraction fitting insertion hole is formed so as to be opened to the outside.

The present invention (the invention according to claim 11)
The method for manufacturing a ceramic heater type glow plug according to
The ninth aspect is characterized in that the insertion hole forming member insertion hole is formed by removing the insertion hole forming member by machining.

The present invention (Claim 9, Claim 10, Claim 1)
According to the invention described in 1), the insertion hole forming member of the electrode extraction metal fitting is inserted before sintering the connector, and the hole is formed by melting or machining after sintering. The diameter, length and shape of the hole can be made without variation.
Insertion of the electrode extraction metal fitting into this hole can be performed easily and reliably, and connection with the lead portion can be ensured.

The present invention (the invention according to claim 12)
The method for manufacturing a ceramic heater type glow plug according to
In the ninth, tenth or eleventh aspect, the connector is buried in the connector in a state where a lead portion at one end of the heating element and an end face or a side face of the insertion hole forming member are in contact with each other. I do.

According to the present invention (the twelfth aspect of the present invention), since the lead portion is reliably exposed in the insertion hole inside the connector, the connection at the time of inserting the electrode extraction metal fitting is ensured.

[0038]

1 to 6 show one embodiment of a ceramic heater type glow plug and a method of manufacturing the same according to the present invention. In these figures, an outline of a ceramic heater type glow plug indicated generally by reference numeral 10 will be described with reference to FIGS.

In the figure, reference numeral 11 denotes a ceramic heating element as a ceramic heater, and a main body of the ceramic heating element 11 is formed of insulating ceramics described later. Here, the ceramics forming the ceramic insulator constituting the ceramic heating element 11 refers to all inorganic materials. For example, alumina, zirconia,
Including cordierite, silicon nitride, silicon carbide, or a composite thereof. In particular, among these, silicon nitride and silicon carbide which are sintered through a liquid layer, have high strength at high temperatures, and have excellent thermal shock resistance are desirable.

Reference numeral 21 denotes a metal outer cylinder made of a pipe or the like fitted to the outer peripheral portion of the ceramic heating element 11 and joined by brazing or the like. This is a tubular housing that serves as a fitting for attaching the glow plug 10 to a cylinder head of an engine. On the outer peripheral portion on the rear end side of the tubular housing 22, a screw portion 22a serving as a means for screwing into a mounting hole of a cylinder head of the engine is formed.

Reference numeral 24 denotes an external connection terminal held at the rear end of the tubular housing 22 via an insulating bush 25. A connection end 24a is formed at an inner end of the external connection terminal 24 for connecting a connection end 18b of an electrode extraction metal fitting 18 for electrical connection with the ceramic heating element 11. Here, in such a ceramic heater type glow plug 10, the outer peripheral portion of the tubular housing 22 having the screw portion 22a for screwing and fixing the mounting hole provided in the cylinder head becomes a seat surface portion except at least the screw portion 22a. It is preferable to perform induction hardening as a heat treatment on a portion reaching the tip. The structure and function of such a glow plug 10 are as widely known in the related art, and a description thereof will be omitted.

As shown in FIGS. 1, 4, 5, and 6, a heating element 13 made of an inorganic conductive material or a refractory metal material is provided in a ceramic insulator 12 constituting a main body of the ceramic heating element 11. And both ends 13a, 1 of the heating element 13
One end 14a, 15a is connected to 3b, and lead portions 14, 15 for taking out electrodes from the outside of the heater are embedded in the ceramic.

Then, the connection end 14 of the one lead portion 14
b is exposed to the outer peripheral portion near the rear end of the ceramic insulator 12 and is electrically connected to the metal outer cylinder 21 by brazing or the like. This electrical connection generally becomes a negative electrode. Note that a conductive layer (a portion corresponding to the connection portion 14b) around the ceramic insulator 12 is provided on the exposed portion of the lead portion connection end 14b so that electrical connection with the metal outer cylinder 21 can be reliably performed. (Not shown).

The connection end 15b of the other lead 15
Is a connector 1 made of a ceramic molded body or a ceramic sintered body, for example, having a cylindrical shape at a position where the rear end of the ceramic insulator 12 is not exposed to the rearmost end.
7 and is electrically connected to the electrode extraction fitting 18. This electrical connection generally becomes the positive electrode. The electrode extraction metal fitting 18 is extracted from the rear end of the ceramic insulator 12 and extends rearward.

As shown in FIGS. 2A and 2B, the connector 17 made of the ceramic molded body or the ceramic sintered body has a cylindrical shape or a rectangular tube shape, and has an inner hole 17a. The connection end 1 of the lead 15
Hot pressing is performed with the 5b inserted, and then the connection end 18a of the electrode extraction metal fitting 18 is inserted through the insertion hole 17b opened in one of the cylindrical connectors 17 and brazing is performed, so that the whole is integrated. Into a bonded state.

In this embodiment, the holes 17a and 17b are provided in parallel with the connector 17 and partially in communication.
The side surface of the connection end 15b of the lead portion 15 inserted into the hole 17a is configured to be electrically connected by contacting the side surface of the connection end 18a of the electrode extraction fitting 18. With such a configuration, there is an advantage that the connection area between the lead portion 15 and the electrode extraction fitting 18 is increased, electrical connection is ensured, and mechanical strength is increased.

According to the present invention, the electrode extraction portion at the rear end of the ceramic heating element 11 is configured as shown in FIGS. That is, in the ceramic heating element 11, the connection end of the lead 15 is
The rear end of the ceramic insulator 12 is electrically connected to the electrode extraction fitting 18 at a position not exposed to the rearmost end.
2 at the rear end side of at least 5 times (for example, 20 mm or more) the diameter (for example, 3.5 mmφ) of the ceramic insulator 12 from the foremost end of the ceramic insulator 12.
3 so as not to be affected by the heat.

A method of manufacturing the ceramic heating element 11 (ceramic heater) including such an electrode extraction portion will be described below. That is, the heating element 13 and the lead 1
4 and 15 are embedded in a ceramic molded body for forming the ceramic insulator 12. As the embedding method, a conventionally known general method such as an injection molding method, a uniaxial pressing method, a casting method, a gel casting method, or the like can be employed. Among them, the uniaxial pressing method is most preferable from the viewpoint of yield, formability, automation and the like.

In more detail, the ceramic insulator 1
A half amount of the granular powder of 2 is placed in a mold, and a heating element 13, a W filament serving as leads 14, 15 are placed thereon, and a lead 15 extending to its rear end is further placed. A connector (made of a ceramics molded body or a ceramics sintered body) whose connection end 15b is formed in a cylindrical shape 17
, And cover it with the other half of the granular powder.

At this time, the holes 17a and 17b of the cylindrical ceramic connector 17 are so formed that the lead portion 15 is not oxidized.
Of the above, the end of the hole 17b into which the connection end 18a of the electrode extraction metal fitting 18 is inserted may not be exposed to the rearmost end of the ceramic insulator 12. After hot pressing described later, the last end of the ceramic insulator 12 is cut,
It is sufficient that the opening end of the hole 17b can be exposed.

After the molded body to be the ceramic insulator 12 molded as described above is degreased, hot press firing is performed. For example, the molded body is arranged in a graphite mold, and 1700
Perform hot pressing at a temperature between 2000C and 2000C. When hot pressing is performed at a temperature lower than 1700 ° C., the sintering of the ceramics does not proceed sufficiently. In addition, when the ceramics is silicon nitride, the α phase remains in the sintered body, and properties such as strength deteriorate. Further, if hot pressing is performed at a temperature higher than 2000 ° C., silicification of pure W proceeds excessively, and the resistance increases. Therefore, the hot press temperature is 1700 ° C. to 2
Must be in the range of 000 ° C.

Thereafter, the ceramic insulator 12 in which the heating element 13 is embedded is ground into a cylindrical shape, and the top end thereof is ground into a hemispherical shape. Since the cylindrical connector 17 is embedded in the rear end, a hole 17b is opened. Note that, as described above, the cylindrical connector 17 is formed so that the lead 15 is not oxidized.
If the opening of the hole 17b is not exposed to the rear end, the rear end of the insulator 12 is cut off to expose the hole 17b.

The ceramic insulator 1
2, the hole 17b of the cylindrical connector 17 exposed at the rear end.
An electrode extraction bracket 18 made of, for example, a Ni wire resistant to oxidation different from the material of the lead portion 15 is passed through the inside of the hole 1.
By contacting W (lead portion 15) contained in 7b, electrical conduction can be obtained by silver brazing or the like.

Here, the electrical joint portion of the cylindrical molded body 17 is not suitable at a position where the heat generation temperature of the ceramic heating element 11 becomes high. That is, as described above, in the ceramic heating element 11 having a diameter dimension of 3.5 mmφ, the electrical bonding is performed at a distance of about 5 to 12 times as large as the tip of the ceramic heating element 11 (for example, 20 mm to 40 m).
m) You have to be more than a distance away.

The material of the lead portions 14 and 15 is made of an inorganic conductive material or a high melting point metal material, for example, W, like the heating element 13.
Reference numeral 8 is formed of a different material, for example, Ni (nickel). However, according to the present invention, the electrical connection is performed by using the cylindrical connector 17 as described above, and a reliable connection state can be obtained.

The inorganic conductive material for forming the heating element 13 and the like is defined as 4a, 5a in the periodic table.
It refers to a conductive inorganic material containing at least one of nitrides, silicides, carbides, and borides of the a and 6a groups. Further, the high melting point metal material has a melting point of 2000 ° C. or more, such as W (tungsten), Mo (molybdenum), and Hf.
Metals such as (hafnium) and Re (rhenium) and alloys thereof.

The electrode extraction bracket 18 is made of a material different from the above-described lead portions 14 and 15, for example, Ni.
A wire, a Ni-plated Fe wire, a stainless steel wire, or the like can be used, and is preferable because it has excellent oxidation resistance. The metal outer cylinder 21 may be made of known heat-resistant steel such as stainless steel or Inconel, or free-cutting steel or carbon steel.

Here, the ceramic molded body to be the connector 17 is a solidified ceramic powder. It is preferable to employ a general ceramic molding method such as extrusion molding, casting molding, press molding, or CIP molding, and to mold in a shape with a hole. The ceramic sintered body is obtained by firing the above-mentioned ceramic molded body, and includes a semi-fired body. Either a molded body or a sintered body is selected depending on whether or not the perforated ceramic molded body or the ceramic sintered body has a strength that is easy to handle.

The metal wire (lead 15) to be inserted into the hole 17a of the connector 17 made of a ceramic molded body or ceramic sintered body and joined is, for example, a high melting point metal having a melting point of 2000 ° C. or more. It is desirable to use one made of a material. However, the present invention is not limited to this, and may be selected according to various conditions.

The ceramic heating element 11 having the above configuration
In the case of manufacturing a ceramic body, the heating element 13 and the lead portions 14 and 15 are assembled into the ceramic insulator 12 by using a ceramic body 19 as shown in FIG. Both ends 13 of a metal wire to be a heating element 13 inserted into 19a and 19b, respectively.
a, 13b and one ends 14a, 15a of the metal wires to be the lead portions 14, 15 are buried in ceramic powder, and these are sequentially joined by firing.

According to such a structure, the holes 19a, 19
b, a metal wire (heating element 13) is spirally wound around and attached to a ceramic body 19 having an opened b.
Metal wires (14, 15) serving as leads are connected to each of them, and buried in ceramic powder.
By sintering in either an inert atmosphere or a reducing atmosphere, the required end of the joint is pressed by the shrinkage of the ceramic during the sintering step, and a joined body that is satisfactory in terms of strength and electrical properties can be obtained. It is.

In the ceramic heating element 11 described above, the connection of the electrode extraction fitting 18 to the electrode extraction section provided at the rear end of the ceramic insulator 12 is performed as shown in FIGS. 3, 7, and 8. be able to. 3 (a), 3 (b), 7 (a) and 7 (b) show the connector 17 incorporated at the rear end of the ceramic insulator 12 for taking out an electrode. When the connector 17 is made of a ceramic molded body or a ceramic sintered body, the connector 17 is actually made of a ceramic insulator 12 after firing.
It is integrated so that it cannot be distinguished.

In the ceramic insulator 12 to be the ceramic heating element 11 formed as described above, the hole 17b or the hole 17a exposed on the rear end face is
The connection end 18a of the electrode extraction metal fitting 18 is inserted, and the portions exposed from the holes 17b and 17a may be joined by brazing with a brazing material 28.
8a may be inserted into the hole 17a, and a brazing material 28 may be poured into a gap between the hole 17a and the connection end 18a and brazed. In this manner, the electrode extraction fitting 18 can be integrally connected to the rear end face 11a of the ceramic heating element 11.

Here, FIG. 3A shows the case where the inner diameters of the holes 17a and 17b of the connector 17 formed of insulating ceramics are substantially constant, and FIG. 3B shows the holes 17a and 17b.
In this case, the inner diameter of each of the electrodes is made different, and the insertion side of the electrode extraction metal fitting 18 is made thicker to prevent buckling during insertion. The example of FIG. 3 shows a case where the side surfaces of the connection ends 15b and 18a are brought into contact with each other for connection.

In the example shown in FIG. 7, one hole 17a is formed in a connector 17 formed of insulating ceramics, and a connection end 15b of a lead 15 inserted from both ends of the hole 17a and a connection end 18a of an electrode extraction metal fitting 18. Are electrically connected by end-to-end contact. FIG. 7A shows a case where the inner diameter of the hole 17a of the connector 17 is constant.
(B) shows a case where a step is formed in the inner diameter of the hole 17a to make the electrode extraction metal fitting 18 thicker so that buckling does not occur during insertion.

FIGS. 8A and 8B show another embodiment. In this embodiment, the connector 17 is made of a conductive ceramic or a high melting point metal. This is a case where the molded cylindrical ceramic molded body 17 is molded from a ceramic conductive material. When the connector 17 is formed of a conductive material in this way, there is no need to make the connection end 15a of the lead portion 15 and the connection end 18a of the electrode extraction metal fitting 18 contact, so that electrical connection can be performed more reliably.

In FIG. 8A, one hole 1 is formed in the connector 17.
7a, the connection end 15a of the lead portion 15 and the connection end 18a of the electrode extraction metal fitting 18 are inserted from both ends thereof, and electrical connection is made to the connector 17 at a position where the tips are separated from each other by brazing or the like. Is going. FIG.
In (b), holes 17a and 17b are opened in the connector 17 at different positions, and the connection end 15a of the lead portion 15 is formed in each hole.
And the connection end 18a of the electrode extraction bracket 18 are separately inserted,
Each is electrically connected to the connector 17 by brazing or the like.

In this embodiment, since the electrical connection between the lead portion 15 and the electrode extraction metal fitting 18 is made via the connector 17, it is not necessary to directly connect the connection ends of each other. More reliable.

In the above-described embodiment, as shown in FIGS. 4 and 5, the portion of the metal outer cylinder 21 corresponding to the rear end of the ceramic heating element 11 is connected to the tubular housing 22.
3 shows a case where the head is held at the front end of the head. In this structure, reference numerals 11c, 21a, and 22b in FIG. 4 denote a peripheral edge of a rear end portion of the ceramic heating element 11, a peripheral edge of a rear end portion of the metal outer cylinder 21,
The tapered portion is formed on the inner peripheral edge of the distal end portion of the tubular housing 22. By forming such tapered portions 11c, 21a, 22b, the workability at the time of assembling the respective parts is improved, and, for example, the work of joining the metal outer cylinder 21 and the tubular housing 22 by press fitting or the like is easy. become.

The ceramic heating element 11 formed as described above may be incorporated in the tubular housing 22 as shown in FIGS. 9 (a), 9 (b) and 9 (c). That is, in FIG. 9A, a metal outer cylinder 21 provided on the outer periphery of the ceramic heating element 11 is formed to be long, and
1 shows a case where the rear end of the glow plug 10 is held at the front end of the tubular housing 22, so that the front end of the glow plug 10 can be made thinner and longer.

FIG. 9B shows a case where the metal outer cylinder 21 is connected to the longitudinal center of the ceramic heating element 11 and held at the tip of the tubular housing 22. c) shows a case where the above-mentioned metal outer cylinder 21 is omitted and the tubular housing 22 is used in place of the metal outer cylinder, and the ceramic heating element 11 is directly held at the end thereof. Here, the joining of the ceramic heating element 11 and the metal outer cylinder 21 (or the tubular housing 22) may be generally performed by brazing. Further, the joining between the metal outer cylinder 21 and the tubular housing 22 is performed by brazing or press-fitting,
Caulking and other plastic working may be performed.

However, in the above-described embodiment, the ceramic heating element 1 of the ceramic heater type glow plug 10 is used.
As a connection structure between the lead portion 15 and the electrode extraction metal fitting 18, the connection end 15b of the lead portion 15 is inserted into a connector 17 made of a ceramic molded body or a ceramic sintered body, and the rearmost end of the ceramic heating element is formed. The electrode 15 is inserted into a hole formed in the end face of the connector 17 and then the lead 15 and the electrode 18 are connected by brazing. Such a problem may occur.

That is, after the connector 17 is hot-pressed and fired, the hole 17b into which the electrode extraction metal fitting 18 is inserted is formed.
It is quite difficult to provide. This is because, in order to form holes after hot pressing (firing), a method using a laser or a method using a diamond drill requires too much labor and cost.

In the method of forming an organic material together with a ceramic molded body and making a hole by burning out the organic material at the time of firing, the hole diameter, the length of the hole, and the like vary widely, so that the electrode extraction metal fitting 18 is securely inserted. Difficult. Further, if a hole is formed in the ceramic molded body and then firing (hot pressing) is performed as a ceramic heating element, the hole may be deformed or crushed, and the electrode extraction fitting 18 may not be inserted.

Also, the lead 15 and the electrode extraction metal fitting 18
Are connected after brazing. However, since the brazing portion of the lead portion 15 is only a cross section of a thin wire, it is difficult to securely connect, and the strength of the connecting portion may not be secured. . Further, depending on the variation of the holes in the ceramic sintered body, the lead portions 15 are not exposed to the holes,
In some cases, the connection between the lead 15 and the electrode extraction fitting 18 cannot be made.

FIGS. 10 to 12 show another embodiment of the glow plug of the ceramic heater type according to the present invention. This embodiment is intended to more reliably form the insertion hole 17a of the electrode extraction metal fitting 18 in order to solve the above-mentioned problem.
Since the present embodiment relates to the formation of the insertion hole 32 of the electrode take-out fitting 18 which opens to the outside, and other configurations are the same as those of the above-described embodiment, illustration and description thereof will be omitted here.

In this embodiment, the connector 17 described above is used.
Then, a member 30 for forming an insertion hole of an electrode extraction metal fitting 18 made of a high melting point metal is buried so that a part thereof is exposed, and after the ceramic heating element 11 is formed, the electrode extraction metal fitting 18 is formed.
By removing the member 30 for forming an insertion hole, the electrode extraction metal fitting insertion hole 32 is formed to be open to the outside.
Here, the above-described member 3 for forming an insertion hole of the electrode extraction metal fitting is described.
Reference numeral 0 denotes a state in which the connection end 15b of the lead portion 15 is buried in the connector 17 in a state where the side face or the end face is in contact with each other, and the outer end is exposed on the outer end face of the connector 17. And

FIGS. 10 and 11 show the application of this embodiment. In FIGS. 10 and 11, (1) to (6) show the steps.

That is, in (1) of FIG. 10, a cylindrical ceramic molded body (1) having a through hole at the center is provided.
7) Lead 15 (whether connected to or not connected to heating element 13) made of a W wire or the like connected to heating element 13 (resistor) not shown in through hole (31) and electrode extraction fitting A high-melting point metal wire 30 (insertion hole forming member) having a diameter larger than the diameter of 18 is inserted in a state where the side surfaces are in contact with each other, and the ceramic sintered body (1) is hot-pressed (fired).
7) is molded. If there is no problem in handling in the subsequent step, the ceramic molded body may be used as it is.

In FIG. 2B, a connector 17 having a heating element 13 connected to the end of a lead 15 is connected to a ceramic heating element 11.
The molded body of the ceramic heating element 11 is buried in the ceramic powder forming the ceramic powder. In (3) in the figure, the formed body of the ceramic heating element 11 is hot-pressed (fired) to form the ceramic heating element 11 (sintered body). At the time of this hot pressing, the lead portion 15 and the high melting point metal wire 30 are fired in a state in which a strong tightening force is applied and the lead portion 15 and the high melting point metal wire 30 are tightly adhered.

In FIG. 4D, the refractory metal wire 30 is exposed on the rear end face 11a of the ceramic heating element 11 fired in the above-described step. Ceramic insulator 12
It is preferable to perform positioning on the high melting point metal wire 30 so that the rear end of the metal wire is exposed during cutting or firing. Then, the exposed high melting point metal wire 30 is removed by machining or melting by cutting or the like.

Here, in the case of removal by machining, only the portion of the hole into which the connection end 18a of the electrode extraction metal fitting 18 can be inserted may be cut without cutting the high melting point metal wire 30 in its entirety. In the case of removal by melting, for example, the refractory metal wire 30 is a Mo wire, the lead 15 is a W wire, and the connector 17 is a silicon nitride material or a silicon carbide material.

This is immersed in, for example, a mixture of sulfuric acid and sulfuric acid to dissolve the Mo wire 30. In the case of a mixture of aqua regia and sulfuric acid, it has been confirmed that the Mo wire 30 of 0.5 mmφ is completely dissolved by immersion for 24 hours. In a mixture of aqua regia and sulfuric acid (acid for dissolution), the Mo wire 30 dissolves, but W
Line 15 does not dissolve.

In (5), a metallizing process and a pre-process for brazing (first process or Ni plating process) in the hole 32 formed as described above are performed. Thereafter, at (6) in FIG.
Then, the lead wire 15 is inserted, brazing is performed, and the lead portion 15 and the electrode lead-out fitting 18 are connected.

Here, it is preferable to use, for example, a Ni wire, a Ni-plated Fe wire, a stainless steel wire or the like as the electrode take-out fitting 18. If the ceramic sintered body is fired in a state where the lead portions 15 and the end faces of the refractory metal wires 30 are butted against each other in (1) of FIG. 10 and the subsequent processing is performed as described above, the connection by butt joining is achieved. A part can be formed. FIG. 11 illustrates a process of forming the insertion hole by melting the above-described insertion hole forming member 30 and brazing the lead portion 15 and the electrode extraction metal fitting 18.

FIG. 12 shows the principle of making a hole in the connector 17 by melting shown in FIG. That is, as shown by (1) in the figure, a 0.5 mmφ Mo wire 3 is so formed that one surface thereof is exposed in a connector 17 made of a silicon nitride molded body or the like.
0, the compact was sintered by hot pressing as shown in FIG. 2 (2), and then immersed in a mixed solution of aqua regia and sulfuric acid for 24 hours as shown in FIG. Dissolve,
The insertion hole 32 can be opened.

A 0.5 mmφ Mo wire (high melting point metal wire) is placed in the above-mentioned silicon nitride molded body (connector 17).
After embedding 30 and sintering the formed body by hot pressing, the sintered body is cut so that the surface of the Mo wire 30 comes out.
Add it to a mixed solution of aqua regia and sulfuric acid as described above for 24 hours.
The insertion hole 32 may be opened by soaking the Mo wire 30 by immersing it for a time. In addition, if the shape of the insertion hole forming member 30 formed of the Mo material is variously changed, a hole having a complicated shape that cannot be formed by machining or laser processing can be formed.

By drilling holes in the connector 17 in this manner, holes with accurate dimensions can be easily formed in a ceramic sintered body that is difficult to process. That is, the diameter and length of the insertion hole 32 of the electrode extraction fitting 18 of the connector 17,
Further, since the shape can be accurately formed without variation, the connection end 18a of the electrode extraction metal fitting 18 can be reliably inserted, and the connection with the connection end 15b of the lead portion 15 can be ensured.

In the embodiment shown in FIG. 8 as well, when the connector 17 is formed of conductive ceramics, the dimensions of the connector 17 can be accurately adjusted by applying the steps shown in FIGS. 10 and 11 described above. Holes can be easily formed. When the connector 17 is formed of a high melting point metal, the insertion hole may be formed by cutting the ceramic heating element 11 after firing.

Although the insertion hole forming member 30 is made of a high melting point metal, the invention is not limited to this.
Any material can be used as long as it can be removed after firing. In addition, in the case of forming the insertion hole by dissolution, the member 30 for forming the insertion hole is made of Mo wire, but is not limited thereto, and may be any material that can be dissolved by an acid.

In the above embodiment, the connector 1
7 is provided to electrically connect the lead portion 15 and the electrode extraction metal fitting 18, but the lead portion 1 is provided without the connector 17.
5 may be electrically connected to the electrode extraction fitting 18.
For example, the lead 15 and the electrode extraction metal fitting 18 are temporarily fixed using an adhesive or a material that burns out when the ceramic heating element 11 is fired, and a molded body of the ceramic heating element 11 is formed in that state, and then fired ( The ceramic heating element 11 may be formed by hot pressing.

Accordingly, in the ceramic heating element 11 of the ceramic heater type glow plug 10, the connection between the lead 15 and the electrode extraction metal fitting 18 is made by the connection end 15b,
When the connection is performed on the side surface 18a, there is an advantage that the connection area is increased, the electrical connection is ensured, and the mechanical strength is increased. Further, since the connection between the lead portion 15 and the electrode extraction metal fitting 18 is performed inside the ceramic heating element 11, the connection can be reliably performed without increasing the size of the ceramic heating element 11 in the radial direction. Therefore, the function and effect of the above-described embodiment, which can sufficiently cope with the development, can be further exhibited.

The present invention is not limited to the structure described in the above embodiment, and it goes without saying that the shape, structure, etc. of each part can be appropriately modified or changed. For example, in the above-described embodiment, the ceramic heater type glow plug 1
Although an example is shown as the structure of the ceramic heating element 11, the metal outer cylinder 21, the tubular housing 22, etc. of the present invention, the present invention is not limited to this, and an appropriate modification may be freely adopted.

A state in which the heating element 13 is incorporated into the ceramic heating element 11 may be combined with a resistor that also functions as an electrode control function in addition to the heating element 13. Further, as the structure of the tubular housing 22, a structure that has been widely known can be adopted.

In short, in the ceramic heater type glow plug 10 according to the present invention, the glow plug 10 can be attached to the cylinder head of the engine by a screw portion, and a part of the tubular housing 22 can secure airtightness. On the other hand, any structure may be used as long as airtightness can be ensured between the ceramic heating element 11 and the metal heating element 11 via the metal outer cylinder 21 or directly.

In the ceramic heating element 11,
As shown in FIGS. 2A and 2B, the cylindrical ceramic molded body 17 to be incorporated into the rear end side of the ceramic insulator 12 may be a cylindrical one or a rectangular one.

Further, in the above embodiment, in the ceramic heater type glow plug 10, the ceramic heater (ceramic heating element 11) and the electrode extraction metal fitting 1 are provided.
Although the description has been given of the opening of the connector 17 as a connection portion with the connector 8, the present invention is not limited to this, and it goes without saying that the connector 17 may be used for opening a ceramic molded product.

[0098]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a connection between a lead portion 15 and an electrode extraction metal fitting 18 is made in a ceramic heating element 11. Therefore, the connection part is the ceramic heating element 1
Expected to be affected by fever from 1. Therefore, a test sample to which the present invention was applied was prepared, a confirmation test of a superheat cooling cycle test was performed, and a ceramic heating element 1 was connected to the connection portion.
The effect of heat generation from No. 1 was confirmed.

[Confirmation Test 1] 91 wt% of silicon nitride, 5 wt% of yttria, 4 wt% of alumina, a binder and a pole made of silicon nitride were placed in a silicon nitride pot, and mixed and pulverized for 24 hours using isopropyl alcohol as a kneading medium. Thereafter, the slurry produced by mixing was dried with a spray dryer to produce granules of about 100 μm.

0.5 mmφ connected to the heating element 13
The lead portion 15 was passed through a half of a cylindrical ceramic sintered body 17 having an outer diameter of 2.5 mm, an inner diameter of 0.6 mm, and a length of 20 mm, and was embedded as shown in FIG. After that, the sample was
Hot pressing was performed at 00 ° C., and grinding was performed to obtain a 3.5 mmφ glow plug tip (ceramic heating element 11 serving as a heating element).

A hole 17a is opened at the rearmost end because the cylindrical ceramic sintered body 17 is embedded.
There, 0.5mmφ Ni wire (electrode extraction metal fitting 18)
And bonding was performed with silver wax BAg-8. Also,
The metal outer cylinder 21 was also joined by silver brazing BAg-8 after metallizing the ceramic insulator 12. As a result, the part to be the negative electrode can be electrically joined. After that, the length of the mounting screw portion 22a becomes M8, and the length is 200 m.
The m-shaped tubular housing 22 was assembled to produce the ceramic heater type glow plug 10 shown in FIG.

The saturation temperature at a point 2 mm from the tip of the ceramic heater type glow plug 10 is set to 1300 ° C. at 14 V, and the power supply is turned on for 30 seconds each.
Heating / cooling cycle test was performed 50,000 times by heat-generating by N and air cooling for 30 seconds (this test guarantees almost 100,000 km under actual vehicle conditions). As a result of such a test, disconnection of the heat generating portion, disconnection of the lead and the metal fitting, bending of the tubular housing 22 and the metal outer cylinder 21 did not occur, and the test was cleared 50,000 times.

Further, with the whole being supported by the rear end portion (fulcrum position in FIG. 5) of the ceramic heater type glow plug 10, a pin is placed at a point (load point) 3 mm from the foremost end of the ceramic heating element 11. By applying a predetermined load at the points, the anti-deposition strength was investigated. In this confirmation test, the portion of the ceramic heating element 11 described above did not break at all, and was bent at the portion of the metal outer cylinder 21 containing no ceramic insulator 12. This indicates that "re-bending" is possible even if bent at the time of mounting or manufacturing.

[Confirmation Test 2] A ceramic heater type glow plug 10 was manufactured in the same manner as in the confirmation test 1 described above. The joining position of the lead portion 15 and the Ni wire, which is the electrode extraction metal fitting 18, is set at one position from the top of the ceramic heating element 11.
0mm, 15mm, 20mm, 25mm, 30mm, 4
0 mm. Also, the ceramic heating element 11 of Ni wire is used.
Bonding to the rear end was performed with an active silver braze.

Thereafter, when the saturation temperature at a point 2 mm from the tip of the ceramic heater type glow plug 10 is
The heating and cooling cycle test was performed 50,000 times by setting the temperature to 00 ° C., turning on the power for 30 seconds to generate heat, and air cooling for 30 seconds. (This test is equivalent to approximately 100,000 km under actual vehicle conditions, and it is possible to guarantee a durability of 100,000 km).

The results of the above test are shown in Table 1 below, and it has been confirmed that the joint position with the electrode extraction fitting 18 should be 20 mm or more.

[0107]

[Table 1]

[0108]

As described above, according to the ceramic heater type glow plug and the method of manufacturing the same according to the present invention, the connection between the lead portion and the electrode extraction metal fitting is performed inside the ceramic heating element. Does not increase in the radial direction, and it is possible to cope with a reduction in the diameter of the glow plug.

Further, according to the present invention, the connector is buried in the ceramic powder, and the ceramic heating element for firing it is molded, and the connection with the electrode extraction metal fitting can be reliably performed in the ceramic heating element. . Therefore, since the connection is made in the rear end portion of the ceramic heating element, no space is required, especially a space in the radial direction of the ceramic heating element, and the diameter does not increase.

Further, according to the present invention, the joint for extracting the electrode between the other lead portion embedded in the ceramic heating element constituting the ceramic heater and the electrode extraction metal fitting is formed by the influence of the heat of the heating element on the ceramic heating element. The glow plug can be used for a long time without glowing because it is performed on the rear end side that is far enough to receive no damage, and the durability of the glow plug can be greatly improved, for example, it is not necessary to replace it until it is scrapped Can be.

Further, according to the present invention, since the strength of the ceramic heating element can be improved, the diameter and length of the ceramic heating element, the metal outer cylinder and the tubular housing holding the ceramic heating element in the glow plug can be increased. Can be achieved. Further, according to the present invention, the thickness of the tubular housing of the glow plug is reduced so that the so-called mounting screw diameter becomes M10 to M8, and the diameter of the ceramic heating element in the ceramic heater type glow plug is 3.5 mmφ. Even if the degree is small, electrical connection can be easily performed, so that the diameter and length of the entire glow plug can be reduced.

Further, according to the present invention, the lead portion and the electrode extraction metal can be electrically connected by the presence of the connector embedded in the ceramic powder for forming the ceramic heating element. Therefore, the electrode lead-out portion of the other lead portion of the heating element embedded in the ceramic insulator constituting the ceramic heater is connected to a cylindrical connector (ceramic molded body or ceramic sintered body) embedded in the rear end of the ceramic insulator. ) And an electrode extraction metal fitting joined thereto, the diameter of the ceramic insulator serving as the ceramic heater is 3.5 mmφ.
Even if the degree is small, electrical connection can be easily and reliably performed.

Further, in the present invention, when the connector is formed of conductive ceramics or a high melting point metal, a reliable electrical connection state can be ensured even though the contact between the lead portion and the electrode extraction metal becomes unnecessary. .

According to the present invention, the member for forming an insertion hole of the electrode extraction metal fitting is inserted before sintering the connector, and after sintering, the member for forming the insertion hole is removed by cutting or melting. Since the holes are formed, the diameter, length, and shape of the holes can be made without variation. Insertion of the electrode extraction metal fitting into this hole can be performed easily and reliably, and connection with the lead portion can be ensured. Therefore, no cost is required to form an insertion hole for inserting the connection end of the electrode extraction metal fitting into the ceramic connector, and the dimensional accuracy of the insertion hole and an appropriate hole shape can be obtained.

Further, according to the present invention, it is possible to form an insertion hole of an electrode extraction metal fitting in a ceramic sintered body that is difficult to process by a simple method, and to accurately form the diameter and length of the insertion hole without variation. As a result, the electrode extraction fitting can be reliably inserted, and the connection with the lead portion can be ensured. In addition, if the hole forming member is appropriately selected, a hole having a complicated shape that cannot be formed by machining or laser processing can be formed.

Further, in the present invention, it is not necessary to open the insertion hole for inserting the connection end of the electrode extraction fitting into the connector, and it is possible to obtain the dimensional accuracy of the insertion hole and an appropriate hole shape. Even if the tubular housing of the glow plug is made thinner, that is, the diameter of the mounting screw of the tubular housing is made thinner from M10 to M8, and the ceramic heating element has a diameter of 3.5 mmφ or more, electrical connection is easy. Thus, it is possible to provide a ceramic glow plug which does not cost much.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of a ceramic heater-type glow plug and a method for manufacturing the same according to the present invention, and illustrating an outline of a ceramic heater (ceramic heating element).

2A is an end view showing a rear end face of the ceramic heating element of FIG. 1, and FIG. 2B is an end view showing a modification thereof.

FIG. 3 (a) is a view showing a connection between a lead portion and an electrode extraction metal when a connector (ceramic molded body or ceramic sintered body) is formed of insulating ceramic at an electrode extraction portion at a rear end portion of a ceramic heating element. FIG. 7B is an enlarged cross-sectional view of a joint portion, and FIG.

FIG. 4 is a sectional view of an essential part for explaining a structure for assembling the ceramic heating element (ceramic heater) shown in FIG. 1 to a tubular housing side.

FIG. 5 is an overall sectional view showing one embodiment of a ceramic heater type glow plug and a method for manufacturing the same according to the present invention.

FIG. 6 is a sectional view showing an example of a ceramic heater in the ceramic heater type glow plug according to the present invention.

7 (a) and 7 (b) show a case where a connector (ceramic molded body or ceramic sintered body) is formed of insulating ceramic at an electrode extraction portion at a rear end of the ceramic heating element shown in FIG. It is an expanded sectional view explaining the modification of the joint part of the lead part and electrode extraction metal fitting of this.

8A and 8B are modified examples of FIGS. 3 and 7, wherein FIG. 8A shows a lead and an electrode when a connector is formed of conductive ceramics or a high melting point metal at an electrode extraction portion at a rear end of a ceramic heater; Enlarged cross-sectional view of the joint with the take-out bracket,
(B) is an enlarged sectional view showing the modification.

FIGS. 9A, 9B, and 9C are cross-sectional views of a main part of the ceramic heater-type glow plug according to the present invention, illustrating a structure of assembling the ceramic heater to the tubular housing side.

FIG. 10 shows another embodiment of the ceramic heater type glow plug and the method of manufacturing the same according to the present invention, and shows a method of manufacturing an insertion hole of an electrode extraction metal fitting for a connector buried in a ceramic heating element and extraction of an electrode. It is explanatory drawing for demonstrating the connection state of a metal fitting.

FIG. 11 is a view for explaining manufacturing steps corresponding to (1) to (5) of FIG. 10;

12 is an explanatory view for explaining the principle of a manufacturing method for manufacturing an insertion hole of an electrode extraction metal fitting for a connector embedded in a ceramic heating element according to FIGS. 10 and 11 by melting. FIG.

[Explanation of symbols]

10: ceramic heater type glow plug, 11: ceramic heating element (ceramic heater), 11a: rear end face,
12: ceramic insulator, 13: heating element, 13a, 1
3b ... ends, 14, 15 ... leads, 14a, 15a ...
One end, 14b, 15b ... connection end, 17 ... connector (ceramic molded body or ceramic sintered body), 17a, 1
7b: hole, 18: electrode extraction bracket, 18a: connection end, 1
8b: connection end, 21: metal outer cylinder, 22: tubular housing, 22a: screw portion, 24: external connection terminal, 24a: connection end, 25: insulating bush, 28: brazing material, 30: insertion of electrode extraction metal fitting Hole forming member, 31 ... hole, 32 ... electrode extraction metal fitting insertion hole.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Zhao Zhao 2-11-6 Shinmeicho, Higashimatsuyama-shi, Saitama Automobile Equipment Co., Ltd. Matsuyama Plant (72) Inventor Shunji Miura 2--11 Shinmeicho, Higashimatsuyama-shi, Saitama No. 6 Automotive Equipment Co., Ltd. Matsuyama Factory (72) Inventor Takashi Aota 2-11-6 Shinmeicho, Higashi Matsuyama City, Saitama Prefecture Automobile Equipment Co., Ltd. Matsuyama Factory

Claims (12)

[Claims] 1. A ceramic heating element in which a heating element made of an inorganic conductive material or a high melting point metal material is embedded in an insulating ceramic, and an electrode extraction metal fitting electrically connected to a lead portion at one end of the heating element. In the ceramic heater type glow plug, the other end of the lead portion and one end of the electrode extraction metal fitting are electrically connected inside the ceramic heating element, and the other end of the electrode extraction metal fitting is connected to the ceramic heating element. A ceramic heater type glow plug extending from a rear end face. 2. The ceramic heater type glow plug according to claim 1, wherein the other end of the lead portion and one end of the electrode extraction metal fitting are connected to each other.
A ceramic heater type glow plug, wherein the glow plug is electrically connected inside a connector embedded in a rear end of the ceramic heating element. 3. The ceramic glow plug according to claim 1, wherein the other end of the lead portion and one end of the electrode extraction metal fitting are connected to each other.
A ceramic heater-type glow plug, wherein the ceramic heater is electrically connected at a rear end side at least five times a diameter of the ceramic heater in an axial direction from a front end of the ceramic heater. 4. The ceramic heater type glow plug according to claim 2, wherein the connector has an insertion hole for an electrode extraction metal fitting that exposes a part of the lead portion, and the insertion hole includes the electrode extraction metal fitting. A ceramic heater-type glow plug, wherein one end of the glow plug is electrically connected to the other end of the lead portion. 5. The ceramic heater type glow plug according to claim 2, wherein the connector is formed of conductive ceramics or a high melting point metal, and the other end of the lead portion and one end of the electrode extraction metal fitting are connected to each other. A ceramic heater-type glow plug electrically connected via a connector. 6. The ceramic heater-type glow plug according to claim 2, wherein the other end of the lead portion and one end of the electrode extraction metal fitting are connected to each other.
A ceramic heater-type glow plug characterized in that the end portions or side surfaces of these lead portions and the electrode extraction metal fittings are electrically connected to each other by joining them. 7. The ceramic heater type glow plug according to claim 2, 3 or 4, wherein the connector is formed of a ceramic molded body or a ceramic sintered body. Ceramic heater type glow plug. 8. A ceramic heating element in which a heating element made of an inorganic conductive material or a high melting point metal material is embedded in ceramic, and an electrode extraction metal fitting electrically connected to the other end of one end of the heating element. A method for manufacturing a ceramic heater type glow plug, comprising: embedding the heating element and a connector having at least a part of the lead portion embedded in ceramic powder; A method for manufacturing a ceramic heater type glow plug, characterized by molding. 9. The method of manufacturing a ceramic heater type glow plug according to claim 8, wherein a member for forming an insertion hole of an electrode extraction metal fitting is embedded in the connector so that a part thereof is exposed, A method for manufacturing a ceramic heater type glow plug, comprising: removing a member for forming an insertion hole of the electrode extraction metal fitting after forming the body, thereby opening the electrode extraction metal fitting insertion hole to the outside. 10. The method of manufacturing a ceramic heater type glow plug according to claim 9, wherein the connector is formed of a ceramic molded body or a ceramic sintered body, and the insertion hole forming member is formed of a high melting point metal; A method for manufacturing a ceramic heater-type glow plug, comprising: forming an insertion hole for an electrode extraction fitting outside by dissolving the insertion hole forming member with an acid after molding the ceramic heating element. 11. The method for manufacturing a ceramic heater type glow plug according to claim 9, wherein the electrode extraction metal fitting insertion hole is formed by removing the insertion hole forming member by machining. Manufacturing method of ceramic heater type glow plug. 12. The method according to claim 9, 10 or 1.
2. The method for manufacturing a ceramic heater type glow plug according to claim 1, wherein the lead portion at one end of the heating element and the end face or side face of the insertion hole forming member are in contact with each other and embedded in the connector. Of manufacturing a ceramic heater type glow plug.