JPH03110777A - Built-in photo-sensor type spark plug - Google Patents

Abstract

PURPOSE:To measure the temperature in a combustion chamber and the combustion light signal stably and to obtain an excellent durability by providing an ignition electrode with flange made by fixing a flange to a taper at the igniter side and baking integrally. CONSTITUTION:A flange is fixed to a taper 21 at the igniter side, and an ignition electrode 31 with flange is baked integrally. As a result, no clearance is generated between the ignition electrode 31 with flange or an insulator 2, and an axial hole, no combustion gas invades into the axial hole, and the top end surface of a photo-waveguide body 4 is never contaminated with carbon and the like. Consequently, the temperature in a combustion chamber and the combustion light signal can be measured stably, the ignition electrode 31 is never removed, and the durability of the built-in photo-sensor type spark plug A is made excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spark plug that measures the temperature of a combustion chamber of an internal combustion engine and a combustion light signal.

[Prior Art] An internal combustion engine in which an optical waveguide is provided in the shaft hole of an insulator of a spark plug so as to be exposed to the combustion chamber, and a heat-resistant metal coating that does not transmit light is provided on the tip surface of the optical waveguide. A spark plug that measures the temperature and combustion waveform of a combustion chamber is known (Japanese Patent Laid-Open Publication No. Sho B7-163841).

[Problems to be Solved by the Invention] However, in conventional spark plugs, when the heat-resistant metal coating is repeatedly exposed to the high temperature and high pressure combustion gas of an internal combustion engine, the bonding strength between the coating and the optical waveguide is low, so and peel it off.

An object of the present invention is to provide a spark plug with a built-in optical sensor that can stably measure the temperature of a combustion chamber and a combustion light signal, and has excellent durability.

[Means for Solving the Problems] In order to achieve the above object, a spark plug with a built-in photosensor of the present invention has the following configuration.

a cylindrical metal shell having an outer electrode formed at its tip; an insulator having a tapered shaft hole on the ignition part side and a base side; and an insulator that is fitted and fixed in the cylindrical metal shell; and the ignition part side. a flange firing electrode which is integrally fired with a flange locked to the taper; a conductor whose tip is electrically connected to the flange firing electrode and whose rear end is located behind the base taper; and a conductor located behind the shaft hole. a tubular terminal electrode inserted from the end; a center conductor made of conductive glass that seals the terminal electrode and the conductor in the shaft hole; and an optical waveguide that is inserted through the center conductor and transmits infrared rays.

[Actions and Effects of the Invention] The spark plug with a built-in photosensor of the present invention has the following actions and effects.

(1) The flange is fixed to the taper on the ignition part side, and the flange-attached ignition electrode is integrally fired. Therefore, there is no gap between the flanged firing electrode and the shaft hole of the insulator, and combustion gas does not enter into the shaft hole.Therefore, the tip surface of the optical waveguide is not contaminated with carbon, etc. The temperature of the combustion chamber and the combustion light signal can be measured stably.

(2) There is no deterioration of the optical waveguide due to contamination.Also, the flanged ignition electrode is integrally fired with the flange locked to the taper on the ignition part side, so the adhesion strength is high and the flanged ignition electrode does not fall off. There is no need to worry. Therefore, the spark plug with a built-in optical sensor has excellent durability.

[Example] An example of a spark plug with a built-in photosensor according to the present invention will be described with reference to FIGS. 1 to 3.

The spark plug A' with a built-in optical sensor has a cylindrical metal shell 1 with an outer electrode 11 welded to the tip thereof, and a shaft hole 23 with a taper 21, 22, and is fitted into the cylindrical metal shell 1 and fixed. The insulator 2 has a flange attached to the taper 21 and is integrally fired with a flange firing electrode 31, the tip of which is the flange ignition type 8i! 31 and whose rear end is located behind the taper 22, a tubular terminal electrode 33 inserted from the rear end of the shaft hole 23, and the terminal electrode 33 and the conductor 32.
A central conductor 3 made of conductive glass 34 is sealed in the shaft hole 23, and an optical fiber 4 is inserted into the central conductor 3 with its tip abutting the firing electrode 31.

The cylindrical metal shell 1 (made of carbon steel) has mounting screws 12 on the outer periphery.
, a tip part with a packing surface 13 formed on the inner periphery, a rear end part which is caulked inward and has a wire packing 14 and an insulating powder 15 arranged thereon, and a center part where a gasket 16 is arranged and a hexagonal part 17 is formed. It consists of a department. The outer electrode 11 (made of heat-resistant metal) protrudes to cover the tip of the insulator 2.

The insulator 2 (fired alumina body) has a small diameter leg portion 24,
The zero leg length section 24, which is made up of a corrugation section 25 at the rear end and a body section 26 at the center, is fixed to the packing surface 13 via a packing 18. Tapers 21,22 are conical surfaces. A plug cap 100 is fitted onto the corrugation portion 25 .

The flanged firing electrode 31 is made of a Pt--Ir alloy, and includes a conical flange portion with a flat end surface, and a rod-shaped portion slightly protruding from the tip surface of the insulator 2.

The conductor 32 has a cylindrical shape and is a low expansion metal tube made of Ni-Fe alloy, Kovar, molybdenum, or the like.

The terminal electrode 33 is made of steel and has a tubular shape. The tip of the terminal electrode 33 is located at the center of the cylindrical metal shell 1, and the outer periphery of the tip is threaded. Terminal type 8i33
A high voltage is applied from the terminal 35 to.

Conductive glass 34 (mainly composed of borosilicate glass powder and copper powder) is heat-sealed between the tip of the terminal electrode 33 and the rear end of the conductor 32 in a gas-tight manner within the shaft hole 23. ,
And an electrical connection between the two is being established. Furthermore, the optical fiber 4 is held within the shaft hole 23.

Optical fiber 4 (fluorine-containing quartz glass, outer diameter 1 m)
In m), a core with a high refractive index is surrounded by a cladding with a low refractive index. The tip end surface of this optical fiber 4 is attached to a firing electrode 3 with a flange.
It is brought into contact with the end face of the conical flange of No. 1. Note that the area between the plug cap 100 and the connector 300 is covered with four layers: a silicon layer, a Teflon layer, an aramid fiber, and a Teflon layer.

Next, we will explain the manufacturing process of spark plug A with a built-in optical sensor (
Main parts) will be explained.

(1) Flammed firing electrode 3 from the rear end side of the shaft hole of the unfired insulator
1 and fix it at the tip of the shaft hole.

(2) Co-fire these. The firing electrode 31 is tightly fixed in the shaft hole 23 by shrinkage of the unfired insulator during firing.

(3) Next, insert the current-carrying body 32 made of a low expansion metal tube such as Ni-Fe alloy or Kovar from the rear end side of the shaft hole 23 of the insulator 2, and connect it to the ignition electrode 31 by electric resistance welding or high-temperature welding. It is soldered using a brazing material.

(4) Insert the optical fiber 4 into the conductor 32 through the shaft hole 23.

(5) Inject and press conductive glass powder from the rear end side of the shaft hole 23, and then insert the terminal electrode 33.

(6) The terminal electrode 33 is heated (around 950°C) while pressurizing (around 40 kg) to melt the conductive glass powder,
The tip of the terminal electrode 33, the rear end of the conductor 32, and the optical fiber 4 are sealed together in the shaft hole 23 in the center of the insulator.

Next, a temperature measurement test of Spark 1 Lug A with a built-in optical sensor will be described.

As shown in Figure 3, spark plug A with built-in optical sensor
The metal shell 1 is attached to the cylinder head 201 of a gasoline engine.
It is screwed through the mounting screw 12 of.

In this engine, 202 is a cylinder, 203 is a piston, 204 is an exhaust boat, 205 is an intake boat, 206
207 is an exhaust valve, and 207 is an intake valve.

In addition, the connector 300 of the optical fiber 4 is made of lead sulfide PbS.
, a detector 301 as a detector consisting of CdS, CdSc, CaAsP, GaP, and Si, and an emissivity compensation circuit 302
, an analog-to-digital converter 303, and a linearizer 304 in this order to a digital display device 305.

Furthermore, the linearizer 304 is connected to a pen recorder 307 via a digital-to-analog converter 306.

When the engine is in operation, fuel burns in the combustion chamber 208 and the temperature of the plug tip increases to a temperature close to that of the combustion chamber 208. As the temperature of the tip of the plug increases, thermal radiation with a relatively long wavelength, that is, infrared rays, is generated from the flanged firing electrode 31 of the center conductor 3, and this infrared rays are received by the optical fiber 4 and transmitted to the detector 301 through the optical fiber 4. . This detector 301 converts infrared radiation into an electrical signal, which is compensated by an emissivity compensation circuit 302. The thus compensated electrical signal is then transferred to an analog-to-digital converter 30.
3 and the display device 305 via the linearizer 304
The temperature inside the combustion chamber 208 is digitally displayed. At the same time, the temperature inside the combustion chamber 208 is continuously recorded by the pen recorder 307 via the digital-to-analog converter 306.

The optical sensor built-in spark plug A of this embodiment has the following functions and effects.

(1) Flammed firing electrode 31, insulator 2, and conductor 32
Since the conductor 32 and the insulator 2 are fired at the same time, there is no gap between them, and the conductor 32 and the firing electrode 31 are joined during firing. Therefore, the combustion gas is
The carbon does not enter the tip surface of the detector 301, and no carbon contamination occurs. In other words, the output of the detector 301 does not fluctuate due to contamination, and the temperature of the combustion chamber and the combustion light signal can be stably measured. Further, since the ignition type 4f131 does not fall off, the durability of the optical sensor built-in spark plug A is high.

(2) Insert the optical fiber 4 into the shaft hole 23 from the rear end side, fill it with conductive glass powder, then insert the terminal electrode 33, and connect the tip of the terminal electrode 33 and the rear end of the conductor 32, and then the optical fiber 4. are heat-sealed together to form the center conductor 3. As a result, the bonding strength between the center conductor 3 and the insulator 2 becomes strong, electrical continuity between the conductor 32 and the terminal electrode 33 is achieved, and the optical fiber 4 is held in the shaft hole 23.

The present invention has the following embodiments in addition to the above embodiments.

The material of the a2 flanged ignition electrode may be PT, Ir alone, or cermet.The cermet may be TiO2, TiC.
, TiN and other titanium compounds, Pt, Pd, or these and noble metals such as Au, Ru, Ag, and Rh are dispersed and fired. Furthermore, Fe as an additive
, Ni, Cr, Co, one or more kinds of rod metals such as Fe-Ni-Cr alloy and/or All 20s, Cr
Oxides such as 2O,, Y, O,, ZrO3, 5i02, La2O3, oxides such as Mo2C5'T''aC, SiC, B, C, and nitrides such as AjN, BN, ZrN, and M.

One or more types of non-oxides such as S12 may be mixed.

b. The conductor may be made of a metal powder, an optical waveguide coated with a metal film, a ceramic powder exhibiting conductivity, etc., which may be made of the following materials, such as a metal powder, an optical waveguide coated with a metal film, or a ceramic powder exhibiting conductivity. The firing electrode 31 is electrically connected to the firing electrode 31 .

The distance between the tip surface of the C0 optical fiber 4 and the end surface of the conical flange portion of the flanged firing electrode 31 is preferably 0 mm to 2 mm. 2
If it exceeds mm, the sensitivity will deteriorate. In addition, optical fiber 4
When the tip end face of the ignition electrode 31 is separated from the firing electrode 31, heat is not directly transmitted to the optical fiber 4, so that deterioration of the optical fiber 4 is less likely to occur.

d. The conductive glass may be a resistor.

e. A configuration may be adopted in which a photoelectric element (photodiode) is arranged inside the connector 300 of the optical fiber 4.

f. An optical fiber made of sapphire glass may be used as the optical waveguide.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a main part of a spark plug with a built-in photosensor showing one embodiment of the present invention, FIG. FIG. 2 is an explanatory diagram showing a temperature measurement system using a plug. In the diagram: 1... Cylindrical metal shell 2... Insulator 3...
・Center conductor 4...Optical fiber (light waveguide) 11・
...Outer electrode 21.22...Taper 23...Shaft hole 31...Flammed firing electrode 32...Conductor 33
... Tubular terminal electrode 34 ... Conductive glass A...
- Spark plug with built-in optical sensor... Cylindrical metal shell 2... Insulator 3... Center conductor 4... Optical fiber (leading wave body) 11... Outer electrode 21.22... Taper 23 ... Shaft hole 31 ... Flammed ignition electrode 32 ... Conductor 33 ... Tubular terminal electrode 34 ... Conductive glass A ... Spark plug with built-in optical sensor Fig. 1

Claims (1)

[Scope of Claims] 1) A cylindrical metal shell with an outer electrode formed at the tip, and a shaft hole tapered on the firing part side and the base side, and is fitted and fixed into the cylindrical metal shell. an insulator, a flanged firing electrode which is integrally fired with a collar locked to the taper on the firing section side, a tip end electrically connected to the flanged firing electrode, and a rear end located rearward from the base side taper; a conductor, a tubular terminal electrode inserted from the rear end of the shaft hole, a center conductor made of conductive glass that seals the terminal electrode and the conductor in the shaft hole, and a tip end of the firing electrode. and an optical waveguide that is inserted into the center conductor in contact with or in close proximity to the center conductor and transmits infrared rays.