JPS5940481A - Ignitor plug - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an igniter plug used in gas turbine engines for aircraft, etc., and its purpose is to introduce air into the plug to remove the porcelain insulator and the rapidly wearable center electrode tip. By cooling, overheating is prevented and wear resistance is improved.

Conventionally, as an igniter plug employing this type of air introduction method, the one described in USP No. 3,330,911 shown in FIG. 1 is known. In this igniter plug, the porcelain insulator is divided into three parts, an upper part L and a lower part λ, which are disposed in the inner cavity of the mounting bracket T so as to be partially overlapped in the axial direction, and the above-mentioned upper insulator There is a first outer annular space j along the longitudinal direction between the body l and the inner wall surface of the mounting bracket.
is formed, and an upper inlet port ≠a is opened there.

Since the lower insulator λ is fixed to the step part /-2 of the mounting bracket inner cavity via the airtight packing /3, the upper inlet port < za
The downward flow of the airflow from the porcelain insulator is interrupted here, and therefore the airflow passes through the upper porcelain insulator/lower end l≠ and ascends through the intermediate annular space formed by the upper and lower porcelain insulators overlapping each other, and further airflow continues. is inverted from the top /J- of the lower porcelain insulator and faces downward into the inner annular space 7 between the center electrode 3 and the lower porcelain insulator, and connects the outer periphery of the ignition tip 3a at the tip of the center electrode 3 and the lower porcelain insulator. It flows out toward the space of the spark gap l from the open lower a formed by the inner end surface 2a of the insulator. On the other hand, another lower inlet +b is provided at the bottom of the mounting bracket, which opens into the second outer annular spacer between the mounting bracket ≠ inner wall surface and the lower porcelain insulator, and passes through the annular spacer to the tip of the mounting bracket. Opening ll around the formed outer electrode IO
form an air flow path leading to the first circular space j
As described above, air circulation between the spacer and the second outer annular spacer is blocked by the airtight packing /3.

Therefore, it was essential to provide the air inlets at mutually independent upper and lower λ locations. For this reason, if the tip of the mounting bracket protrudes deeply into the combustion chamber of the gas turbine, the lower inlet installed in the secondary air chamber must be located on the upper side, making the overall length of the igniter plug significantly longer. Furthermore, the secondary air chamber on the engine side had to be expanded, which was uneconomical. Furthermore, providing a through hole in the radial direction of the lower porcelain insulator from the second outer annular spacer to the inner annular space 7 is not practical because cracks are likely to occur due to uneven stress and firing distortion occurs. Understood.

The present invention is a proposal to solve such problems, and the present invention is to provide the air inlet of the mounting bracket at one place in the part inserted into the secondary air chamber of the gas turbine engine, and to install the air inlet of the mounting bracket at one place in the part inserted into the secondary air chamber of the gas turbine engine. To fix the lower insulator to the upper and lower annular spaces, a hollow metal sleeve with multiple cut grooves arranged in parallel in the axial direction of the outer peripheral wall is used instead of the airtight packing. , the air taken in through the one inlet is divided into two systems: the second outer annular space and the first outer annular space j→intermediate annular space t→inner annular space 7, without interrupting the flow between the two. This is achieved by distributing it to

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

FIG. 2 is a longitudinal cross-sectional view of the main parts of the igniter plug of the present invention, and the same structural parts are given the same reference numerals as in the conventional example and will be explained. FIG.
FIG. V is a partially cutaway front view of the metal sleeve, and FIG. 5 is a plan view. Figure 5 is a longitudinal sectional view showing another embodiment.

As shown in FIG. 3, the larger inner diameter portion of the mounting bracket ≠ and the smaller portion containing the outer electrode are separated by a step 2, and the hollow metal sleeve 6 as shown in FIG. It is fixed to the inner cavity of the mounting bracket≠ by the part/, 2.

The metal sleeve /6 is located on the outer side of the center electrode 3 and the lower porcelain insulator, and the outer peripheral wall 23 has a plurality of cut grooves /g arranged in parallel with the axis. An axial air flow path is formed between /l and the inner circumferential surface of the mounting bracket, and the first outer annular space and the second outer annular spacer communicate with each other. The metal sleeve /& is filled with a sealing material such as talc powder between the tubular body /7 and the outer circumferential surface of the lower porcelain insulator 2, and has gaskets 20. ．． 2/, the tip of the tubular body 17, 2.2, is crimped inward. Introduction 0.2 opening into the second outer annular spacer
drill a hole.

In another embodiment shown in FIG. 6, the air inlet 0.2j opens into the first outer annular space above the metal sleeve, but is not provided below the metal sleeve.

The igniter plug of the present invention has the above configuration, and has the seventh
of the tip of the igniter plug when installed in a gas turbine engine as shown in the figure.

The ignition part A is inserted into a combustion chamber 2r equipped with a compressor 26 and a fuel nozzle 27, and the ignition part A is inserted into a combustion chamber 2r equipped with a compressor 26 and a fuel nozzle 27.
Since the part of the mounting bracket having t is located within the secondary air chamber λ, in the embodiments shown in FIGS. It descends inside the outer annular spacer and ejects from the opening /l around the outer electrode IO, exerting a cooling effect on the outer electrode 10 and the tip of the lower ceramic insulator, and the other part is emitted from the second outer spacer. Rising inside the annular spacer and cutting groove ll of metal sleeve/6
r through 9 and from the intermediate annular space t to the lower porcelain insulator 20
Top l! enters the inner annular space 7 through the center electrode 3
, and ejects from the open lower a formed by the outer periphery of the tip ignition tip 3a and the inner end surface λa of the lower porcelain insulator toward the spark gap ♂, and at the same time the tip ignition tip 3a of the center electrode and the porcelain Cool the tip of the insulator. Further, in the embodiment shown in Fig. 1, the air inlet 2j opens into the first outer annular space j above the metal sleeve, so that a part of the incoming air passes through the cut groove /I of the metal sleeve /& and enters the second outer annular space. It descends inside the spacer and is ejected from the opening ii of the outer electrode IQ. The other part ascends the intermediate annular space t,
Top l! The spark ignition tip 3a reverses itself and moves downward in the inner annular space 7, and is ejected from the open lower a of the periphery υ of the ignition tip 3a toward the spark gap t. Similarly, it exhibits a cooling effect when ejected.

Conventionally, tungsten or tungsten alloys, which are strong against sparks and wear-resistant, have been used for the center electrode of high-energy igniter plugs in order to increase spark durability, but because of their poor heat resistance, the heat receiving temperature is SOO℃. Oxide scale is formed on the surface of tungsten, and if the heat-receiving condition at high temperatures continues, the oxide scale formed on the surface of tungsten will enlarge into a layer and peel off.To prevent this phenomenon, is extreme.

The problem was how to lower the heat receiving temperature of the force center electrode.

In the igniter plug of the present invention, the metal sleeve is fixed to the stepped part of the inner cavity of the mounting bracket, and the upper and lower annular spaces are communicated with each other. Cooling air can be circulated through both the inner annular space around the electrode as well as the outer annular space, without the disadvantage of increasing the length of the mounting bracket. This makes it extremely easy to connect the air inlet.

By lowering the heat receiving temperature of the center electrode, the use of tungsten in the ignition part is stabilized and the lack of heat resistance is alleviated. Therefore, it helps prevent the formation of oxide scale on the center electrode and alleviates the wear and tear of the center electrode, and also has the effect of elongating the beam of the spark by ejecting cooling air toward the ignition part, which has a positive effect on the ignitability of the combustion gas. be.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a conventional igniter plug, Fig. 2 is a partially cutaway longitudinal cross-sectional view of the main part of the igniter plug of the present invention, Fig. 3 is a longitudinal cross-sectional view of the main part, and Fig. A partially cutaway front view of a metal sleeve used in the igniter plug of the invention, FIG. 5 is a plan view of one half, FIG. 6 is a vertical cross-sectional view of a main part of another embodiment, and FIG. 7 is a metal sleeve installed in a gas turbine engine. FIG. 3 is a state diagram of the igniter plug.

Claims (1)

[Claims] A hollow porcelain insulator is installed in the inner cavity of the mounting bracket, in which the large-diameter part and the small-diameter part are interconnected by a stepped part, and the hollow porcelain insulator is divided into at least the upper and lower parts in the same manner as the center electrode, and an annular space is formed along both the inner and outer sides of the hollow porcelain insulator. and a narrow annular air flow path communicating with the inner annular space between the ignition tip of the center electrode and the inner annular space and supported by the outer electrode. A hollow metal sleeve having a plurality of cut grooves arranged in parallel along the axial direction is attached to the center electrode and fixed to the stepped portion, and a lower porcelain insulator is bonded to the inside of the sleeve. An igniter plug comprising an air inlet that communicates with the outer annular space in the upper or lower peripheral wall of the mounting bracket.