JP3569769B2 - Igniter plug - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an igniter plug mainly used for a gas turbine of a ground generator.
[0002]
[Prior art]
Conventionally, an igniter plug 1 used for a gas turbine engine is provided with a metal shell 3 having a distal end portion 2 having a small diameter in order to reduce a projecting area into the engine as shown in FIG. An insulator 6 having a central electrode 5 protruding and fitted into the shaft hole 4 is fitted into the metal shell 3, and the front end surface of the insulator 6 is slightly retracted from the front end surface 31 of the metal shell 3, and semi-creeping discharge The surface 61 is formed. At substantially the center of the metal shell 3, a mounting screw portion 34 for mounting on the gas turbine engine is formed. A hexagonal bolt-shaped hexagonal portion 35 is provided on the rear end side of the mounting screw portion 34, and a large diameter portion 33 having a larger diameter than the distal end portion 2 is provided between the mounting screw portion 34 and the distal end portion 2. I have. A cooling vent 32 is formed on the rear end side of the distal end portion 2 of the metal shell 3.
[0003]
Then, as shown in FIGS. 4 and 5, the igniter plug 1 is mounted in the combustion chamber 91 of the gas turbine engine 9.
The combustion chamber 91 is provided with an outer wall 912 and an inner wall 911, and secondary air 93 is supplied between the outer wall 912 and the inner wall 911 to supply air necessary for cooling and combustion.
In addition, a plurality of ventilation holes 9111 are formed at various places in the inner wall 911 to promote combustion and cool the inner wall material. The igniter plug 1 is located near the top of the side surface of the inner wall 911. The metal shell 3, the insulator 6, and the center electrode 5 of the igniter plug 1 are cooled by the secondary air 93, thereby increasing electrode consumption and oxidizing corrosion. It has the function of suppressing the increase.
On the other hand, since the secondary air 93 passes through the discharge gap 63 through the ventilation hole 32 provided in the igniter plug, the electric spark generated between the electrodes moves toward the inside of the combustion chamber 91 due to the inflow of the secondary air 93. It also contributes to improving the ignitability of the fuel.
[0004]
A fuel injection nozzle 95 is provided at the top of the inner wall 911, and the fuel injection nozzle 95 injects atomized fuel 951. The ignition of the fuel is performed by igniting a high-energy electric spark 2 to 5 times per second from an ignition power supply having a maximum energy of 20 kV and 1-2 joules in the igniter plug 1 when the gas turbine engine is started. I have. At the time of this ignition, secondary air 93 having a wind speed of 2 to 3 m / s is sent into the vent 32 of the plug. Then, a turbine (not shown) is driven by the high compression combustion gas generated by the ignition.
[0005]
[Problems to be solved by the invention]
In the igniter plug composed of such components, there is a case where electric spark does not occur between the electrodes of the igniter plug and the engine does not start. It was found that the reason why the electric spark did not occur was that foreign matter was mixed in the igniter plug, which was the cause. That is, as a result of the component analysis, such foreign matter is mainly composed of a metal component that is not included in each component constituting the igniter plug, and the foreign matter leaks electric energy sent from the ignition power supply and causes the igniter plug to leak. Of the discharge gap 63 is prevented from being generated. The ignition failure due to such foreign matter has a great effect on various facilities, such as an emergency generator, in which a momentary power outage is not allowed.
[0006]
An object of the present invention is to provide an igniter plug that can easily and inexpensively prevent foreign substances existing in secondary air from entering the inside of the igniter plug.
[0007]
A metallic shell having a cylindrical shape having a protruding portion inward of the distal end portion and provided with a ventilation hole communicating the inside and outside on the side surface,
An insulator with a shaft hole fitted in the metal shell,
A central electrode protruding from the distal end of the shaft hole of the insulator so as to face the inwardly protruding portion of the inner periphery of the distal end of the metallic shell, and
The gist is that a cylindrical protector that covers the ventilation hole is provided with a gap from the tip .
[0008]
The gist of the invention described in claim 2 is that the area formed by the inner diameter of the protector and the outer diameter of the distal end of the metal shell is greater than or equal to the area of the ventilation hole.
[0009]
According to a third aspect of the present invention, in the first aspect of the present invention, a gap formed by the inner diameter of the protector and the outer diameter of the distal end of the metal shell is formed by the inner circumference of the insulator and the distal end of the metal shell. It is characterized in that it is smaller than the minimum gap formed by the inwardly protruding portion.
[0010]
The invention according to claim 4 is a metal shell having a cylindrical shape provided with an inwardly projecting portion on the inner periphery of the distal end portion, and a vent hole communicating with the inside and outside on a side surface of the distal end portion,
An insulator with a shaft hole fitted in the metal shell,
A central electrode protruding from the distal end of the shaft hole of the insulator so as to face the inwardly protruding portion of the inner periphery of the distal end of the metallic shell, and
The gist is that a net in the form of a net or a slit is provided in the vent hole.
[0011]
According to the first aspect of the present invention, the chance that foreign matter that has flown due to the provision of the protector directly enters the ventilation hole is greatly reduced.
[0012]
According to the second aspect of the present invention, since the area formed by the inner diameter of the protector and the outer diameter of the distal end of the metallic shell is larger than the area of the ventilation hole, the flow rate of the secondary air for cooling air passing through the inside of the igniter plug The decrease is slight.
[0013]
According to the third aspect of the present invention, the gap formed by the inner diameter of the protector and the outer diameter of the distal end of the metal shell is smaller than the minimum gap formed by the insulator and the internal diameter of the metal shell. The foreign matter that remains inside the igniter plug does not directly enter the vent hole, and even when it enters, the protrusion protrudes inward from the inner circumference of the distal end of the insulator and the metal shell. Excreted through the minimum gap formed by
[0014]
According to the fourth aspect of the present invention, the cooling performance of the metal shell, the insulator, and the center electrode does not decrease, the life of the igniter plug is not affected, and the foreign matter that has entered directly enters the ventilation hole. Nothing.
In particular, if the mesh size and the slit interval are set to be equal to or less than the minimum gap formed by the insulator and the inwardly protruding portion of the inner periphery of the tip of the metal shell, foreign matter that is caught in the gap will be igniter plug. Do not enter inside. Further, since the foreign matter that has entered is minute, it is excreted without being caught in the minimum gap formed by the insulator and the inwardly projecting portion of the inner periphery of the distal end of the metal shell.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment) FIG. 1 is a sectional view showing a main part of an igniter plug according to a first embodiment of the present invention.
The igniter plug 100 according to the first embodiment of the present invention includes a cylindrical metal shell 300, an insulator 600, a center electrode 500, and the like, and is mounted on a combustion chamber (not shown) of a gas turbine engine.
The metal shell 300 is formed of a heat-resistant metal made of stainless steel, and a front end 302 formed at the front end of the metal shell 300 has a smaller diameter than the middle section 301 via a tapered surface, and a hexagonal section at the rear end. 303 are formed. A screw portion 304 is provided between the middle portion 301 and the hexagonal portion 303, and the screw portion 304 is screwed to the outer wall mounting portion of the combustion chamber.
[0016]
The inner periphery of the distal end of the distal end portion 302 of the metal shell 300 is bent at substantially a right angle and protrudes as an inward protruding surface 3021. Between the protruding surface 3021 and the tip 501 of the center electrode 500, a creeping discharge gap 602 for discharging along the tip 601 of the insulator 600, a circumferential side of the tip 601 of the insulator 600, and the metal shell 300 A semi-creeping discharge gap 604 having an aerial discharge gap 502 between the protruding surface 3021 and the protrusion surface 3021 is formed.
[0017]
Cooling vents 305 are formed at four equally spaced locations on the rear end side surface of the distal end portion 302 of the metallic shell 300. Further, a cylindrical protector 700 having the same outer diameter as the middle section 301 is welded and joined so as to cover the ventilation hole with a slight gap. The gap is set to be equal to or smaller than the minimum gap between the inwardly protruding surface of the metal shell to be described later and the distal end surface of the insulator leg long portion. That inner diameter .phi.d ₂ of the protector 700 so that the relation is established in 2B> (φ ₂ -φ ₁₎ as shown in FIG. 2 are determined.
[0018]
The insulator 600 is made of a sintered body of alumina, has a shaft hole 400 formed at the center, and the center electrode 500 is fitted therein. The front end is a small leg portion 603 and the rear end is a corrugation 604. The distal end surface 601 of the leg portion 603 of the insulator 600 is slightly retracted from the distal end surface 3022 of the metal shell 300 and is provided as a creeping discharge surface. The rear end of the leg portion 603 has a tapered surface and is in contact with the metal shell 300 with a plate packing interposed therebetween. The gap between the outer periphery of the leg portion 603 of the insulator 600 and the inner periphery of the metal shell 300 is formed so as to be wider toward the tip, and the gap between the outer periphery of the tip of the tip 302 of the metal shell 300 and the inner periphery is formed inward. The gap is smallest between the surface protruding as the protruding surface 3021 and the vicinity of the distal end surface of the leg portion 603 of the insulator 600.
[0019]
The center electrode 500 is formed of a nickel alloy, and has a front end portion 501 protruding from the front end surface 3022 of the metal shell 300 and fitted. The rear end is a terminal section 800 connected to a high-voltage power supply.
[0020]
(Second Embodiment) Next, a description will be given below based on a second embodiment.
The area of the gap formed by the inner diameter of the protector and the outer diameter of the distal end of the metallic shell is set to be smaller than the total area of the ventilation holes 305 provided at the distal end 302 of the metallic shell 300. Have been. That is, when the vent hole is provided four, the inside diameter of the protector 700 such When [phi] D the diameter of the vent holes ^{_{305 (φd 2 2 -φd 1 2}} )> 4 × φD 2 relationship is established .phi.d _Two have been determined. The other points are the same as in the first embodiment. This reduces the intrusion of foreign matter remaining inside the igniter plug, and ensures a sufficient cooling capacity.
[0021]
That is, secondary air is flowing at a considerable flow rate even in the combustion chamber where the foreign matter is scattered even at the time of start-up. If there is no protector, a ventilation hole provided at the tip of the metal shell of the igniter plug Although foreign matter may directly enter the protector 32, the foreign matter is repelled by the protector, and the foreign matter repelled by the fast-flowing secondary air passes through another vent hole opened in the inner wall of the combustion chamber. It goes inside and is excreted.
Further, as shown in FIG. 3, a mesh having a mesh width or a slit width smaller than a minimum gap formed by the insulator and the inwardly projecting portion of the inner periphery of the tip of the metal shell in place of the protector. Alternatively, a slit-shaped net C may be used. As a result, there is no foreign substance remaining inside the igniter plug without lowering the cooling capacity.
[0022]
【The invention's effect】
According to the first aspect of the present invention, the chance of foreign matter entering the ventilation hole is greatly reduced, and thus the ignition failure of the igniter plug can be significantly reduced.
[0023]
According to the second aspect of the invention, since the flow rate of the secondary air for cooling air passing through the inside of the igniter plug does not decrease, the cooling capacity of the metal shell, the insulator, and the center electrode does not decrease, and the igniter plug does not fall. Does not affect the life of the device.
[0024]
According to the third aspect of the present invention, the foreign matter which stays inside the igniter plug does not directly enter the ventilation hole, and is excreted even when it enters, so that the foreign matter is prevented. It does not cause ignition failure of the igniter plug due to intrusion.
[0025]
However, although the cooling capacity may be slightly reduced, it does not become an essential problem in consideration of the usage state of the present igniter plug. That is, the igniter plug need only ignite only when the gas turbine engine is started. Accordingly, since the gas turbine engine is not normally ignited in a steady operation state, the exhaustion of the electrodes due to ignition at high temperature does not become large and the life of the igniter plug is shortened like a spark plug for an automobile engine. It is hard to become. Further, in a steady operation state of the engine, the igniter plug itself melts because the combustion gas does not reach a temperature high enough to melt the metal shell, the insulator, and the like, and ignition failure is unlikely to occur.
[0026]
The invention described in claim 4 can prevent ignition failure of the igniter plug without affecting the life of the igniter plug.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a main part of an embodiment of an igniter plug for a gas turbine according to the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part of an igniter plug for a gas turbine according to the present invention.
FIG. 3 shows another embodiment of the igniter plug for a gas turbine according to the present invention.
FIG. 4 shows a conventional igniter plug for a gas turbine.
FIG. 5 is a sectional view showing a state in which a conventional igniter plug for a gas turbine is mounted on a combustion chamber.
[Explanation of symbols]
Reference Signs List 100 igniter plug 300 metal shell 305 vent hole 500 center electrode 600 insulator 700 protector B Minimum gap

Claims (3)

A metallic shell having a cylindrical shape having a protruding portion inward of the distal end portion and provided with a ventilation hole communicating the inside and outside on the side surface,
An insulator with a shaft hole fitted in the metal shell,
A central electrode protruding from the distal end of the shaft hole of the insulator so as to face the inwardly protruding portion of the inner periphery of the distal end of the metallic shell, and
2. The igniter plug according to claim 1, wherein a cylindrical protector that covers the air hole is provided with a gap from the tip . 2. The igniter plug according to claim 1, wherein an area formed by an inner diameter of the protector and an outer diameter of a distal end portion of the metal shell is equal to or larger than an area of the vent hole. 3. The gap formed by the inner diameter of the protector and the outer diameter of the tip of the metal shell is less than or equal to the minimum gap formed by the insulator and the inwardly projecting portion of the inner circumference of the metal shell tip. The igniter plug according to claim 1, wherein:

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