US3017530A - Igniter plug - Google Patents

Description

- E. W. PIERCE Jan. 16, 1962 IGNITER PLUG 2 Sheets-Sheet 1 Filed Nov. 19, 1956 INVENTOR. faz/d fierae AT'IURNEK E. W. PIERCE IGNITER PLUG Jan. 16, 1962 2 Sheets-Sheet 2 Filed Nov. 19, 1956 INVENTOIR. far/flfiwce A 7' TOANE Y United States Patent 3,017,530 IGNITER PLUG Earl W. Pierce, Flint, Nl'ich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaare Filed Nov. 19, 1956, Ser. No. 623,090 3 Claims. (Cl. 313-115) The present invention relates to ignition devices for fuel burners and more particularly to igniter plugs of the straight or angular type having means for supplying cooling air to the interior thereof, such plugs being generally employed in the ignition of fuel supplied to the combustion chambers of gas turbines. A device of the angular type is illustrated and described in the inventors copending application Serial No. 406,171, filed January 26, 1954, and a device of the straight type i illustrated and described in Patent 2,609,808 to W. A. Bychinsky, issued September 9, 1952.

It has become the practice in the art to provide the steel body of the igniter plug with only a single port for the admission of cooling air to the plug in order to increase the life of the plug by reducing the temperature of the insulator and the electrodes and by minimizing the buildup of carbon deposits on the insulator and on the electrodes. However, this expedient in angle-type plugs has given rise to the problem of interchangeability and the necessity for having available right-hand and lefthand igniter plugs. This problem results from the fact that jet engines are generally provided with at least two igniter plugs, commonly of the angle type, positioned on the surface of the engine shell with their angular portions directed toward each other in order to enable the use of the shortest possible length of ignition cable from the power box to the plugs. It is thus apparent that the single air inlet port would have to be on opposite sides of the shells. Similarly, since but a single air cooling port was used, it was essential to provide means for mounting both the straight and angular type plug in the engine in but a single position so as to locate the plugs with the air cooling port directed in the upstream direction of the air passing through the engine. Thus, not only is it necessary in using the prior art type of construction to fabricate two different models of the same angle-type plug but the necessity for providing all plugs with polarized mounting means to assure proper positioning unduly complicates the assembly procedure of the plug in the engine. A typical construction for assuring proper positioning is that utilizing the polarized mounting flange disclosed and described in the aforesaid patent.

Accordingly, it is an object of the present invention to provide an igniter plug adapted to be positioned in a combustion chamber and so constructed as to provide a cooling stream of air within the plug shell regardless of the installation position on the engine. It is another object of my invention to provide an elbow-type igniter plug so constructed and arranged that air cooling ports are directed upstream to the direction of air flow regardless of the mounting position of the plug on the engine.

These and other objects of my invention are attained by providing an igniter plug having means provided on substantially opposite sides of the shell adapted to direct the flow of air about the insulator and inner surface of the shell and out through the firing end.

A better understanding of my invention may be had by reference to the description which follows and the accompanying drawings in which:

FIGURE 1 is a sectional view through an igniter plug constructed in accordance with my invention;'

FIGURE 2 is a sectional view taken on line 22;

FIGURE 3 is a perspective view of the air deflecting bafile of my invention;

FIGURE 4 is a view with portions broken away and in section showing a further embodiment of my invention;

FIGURE 5 is a view of the igniter plug taken along line 55;

FIGURE 6 is a perspective view of the air deflecting bafile utilized in the embodiment shown in FIGURE 4.

Referring now to FIGURE 1, there is Shown an elbowtype igniter plug of the type more fully described in my aforesaid copending application. The device shown in FIGURE 1 is the preferred embodiment of my invention and comprises a body 1 having a shell portion 3, an angularly connecting shield sleeve portion 5 and a mounting pad 7. As is more clearly shown in FIGURE 5 with respect to the second embodiment of my invention, the mounting pad 7 is provided with a pair of bolt holes 9 the central axes of which lie in the same plane as that of the central axis of the igniter plug thus forming a nonpolarized mounting construction to enable the plug to be mounted in more than a single position in the combustion chamber. As is more fully disclosed in my aforementioned copending application, a center electrode subassembly 11 is positioned within and in spaced relationship to the body 1 and comprises an insulator member 13 having a center electrode 15 positioned concentrically therein, the outer end 17 of the insulator being adapted to receive an electrical cable (not shown) for electrical connection with the upper end of the center electrode.

As has been discussed with reference to the prior art, it has been found necessary to provide the shell 3 with means for introducing cooling air into the space between the insulator 1'3 and the shell. As is clearly shown in FIGURES 1 and 2, the shell 3 is provided with air cooling ports 19 and 21 on substantially opposite sides thereof thus making it possible to mount the igniter plug in either of two positions with the angular shield sleeve portion 5 of the plug directed in either of two positions apart. In this manner, it is no longer necessary to provide the igniter plug with a polarized mounting since either air cooling ports 19 or '21 will be directed upstream of the flow of cooling air through the jet engine.

In order to insure the flow of sufiicient cooling air about the insulator 13 and out through the firing end of the igniter plug, it has been found advisable to provide an air deflecting baffle in the annular space between the insulator and the shell 3 in a position opposite the air cooling ports. As is clearly shown in FIGURES 1 and 2, the air deflecting baffie of my preferred embodiment comprises a tubular member 23 having a plurality of spacer lugs 25 positioned in spaced apart relationship on the outer lower surface thereof, tubular member 23 being adapted for positioning within the shell in spaced apart relationship to both the shell 3 and the insulator 13. As is clearly shown in FIGURES 1 and 3, the tubular deflecting baffie 23 is formed with an upper portion 27 of enlarged diameter which is adapted to be securely positioned upon the enlarged portion 14 of the insulator 13 thus retaining the deflecting baflle 23 in fixed position about the insulator. As is disclosed in detail in my aforesaid patent application, the enlarged upper portion 27 is machined both on its outer cylindrical surface 29 and on its lower end surface 31 to position the center electrode subassembly 11 concentrically within the shell 3 with the center electrode 15 concentric to the lower end 4 of the shell which constitutes the ground electrode of the igniter plug. It should be noted at this point that the air deflecting bafile 23 may be positioned within the shell 3 in any suitable manner other than here described. The provision of the air deflecting baffle precludes the flow of substantial quantities of cooling air entering one set of ports out the oppositely disposed set of ports without contacting the lower end of the insulator with the result that the cooling of the lower end of the igniter plug is made ineffective.

It is thus apparent from the description set forth above that I have provided an igniter plug so constructed as to enable adequate cooling of the plug regardless of whether the plug is mounted in either of two positions in which the elbow portion thereof is directed 180 apart, thus eliminating the need for right and left-hand models of the same plug. Similarly, the need for a polarized mounting is eliminated thus simplifying assembly procedures.

In FIGURES 4, 5 and 6 I have shown a further em bodiment of my invention wherein an air deflecting baflle of a different type than that utilized in my preferred embodiment is positioned in the annular space between the shell 3 and the insulator 13. As is clearly shown in FIGURES 4, 5 and 6 the air deflecting baffle comprises a sleeve-like portion 33 having a pair of oppositely disposed radial flanges 35 extending outwardly from the surface thereof. The sleeve 33 is adapted for relatively close fitting about the lower portion of the insulator 13 with the outer ends of the radial flanges 35 in close fitting contact with the inner Wall surface of the shell 3. The flanges 35 are positioned substantially opposite the air cooling ports 37 and 39 which, as in the embodiment of FIGURE 1, are positioned in the shell 3 in substantially opposie sides thereof.

As is clearly shown in FIGURES 5 and 6, the air deflecting baffle may be formed of a pair of sheet metal stampings which may be secured together by spot welds or any other suitable means to form the sleeve 33 and flanges 35. As shown, the ends of the flanges 35 may be bent over to form circumferentially extending portions 41 which fit against the inner surface of the shell 3. As shown in FIGURE 4, a shoulder 43 may be formed on the inner wall of the shell 3 to support the air deflecting baffle in the annular space between the shell and the insulator 13. A plurality of bypassing ports 45 may be provided in the lower end of the shell 3 in the event it is found that the operation of the plug is being interfered with due to an excess of cooling air being directed into the combustion chamber through the firing end of the plug.

As in the case of the embodiment shown in FIGURE 1, the construction shown in FIGURE 4 enables an igniter plug to be positioned within the combustion chamber in more than a single position while still assuring the availability of cooling air to the plug. Similarly, installation of the plug in the chamber is greatly simplified since there is no longer a need for a polarized mounting means. It should also be recognized that the use of angle-type igniter plugs constructed in accordance with my invention eliminates the necessity for having right-hand and lefthand models of the same plug.

While I have illustrated several embodiments of my 5 invention, it should be understood that other forms of the invention may be adopted, such forms being within the intended scope of my invention as set forth in the claims which follow.

What is claimed is:

1. In an angle-type igniter plug, a body member comprising a shell portion having a sleeve portion extending at an angle from the upper part thereof, a mounting flange provided on the outer surface of said shell portion, at least two continuously open ports provided in said shell portion at positions substantially opposite each other between said flange and the lower end of said shell, a plane through said oppositely disposed ports and the longivtudinal axis of said plug being substantially at right angles to a plane through the longitudinal axis of said sleeve portion and the longitudinal axis of said plug, said mounting flange being non-polarized to enable the igniter plug to be mounted in more than a single position while assuring the availability of cooling air thereto.

2. In an elbow type igniter plug, a body member having a shell portion comprising a ground electrode and a. shield sleeve portion extending at an angle from the upper end thereof and integral therewith, a center electrode subassembly comprising an angle type ceramic insulator and center electrode positioned substantially concentrically within said body in generally spaced apart relationship therewith, a mounting flange provided on the outer surface of said shell portion, at least two continuously open ports provided in said shell portion and each port being on substantially opposite sides thereof between said flange and the lower end of said shell, a plane through said oppositely disposed ports and the longitudinal axis of said center electrode being substantially at right angles to a plane through the longitudinal axis of said shield sleeve portion and said center electrode, said mounting flange being non-polarized to enable the plug to be mounted with said shield sleeve portion extending in one of two opposite directions while assuring the availability of cooling air thereto.

3. An igniter plug as set forth in claim 2, wherein an air deflecting baffle is positioned within said body member between said shell portion and said subassembly to deflect cooling air downwardly and into direct contact with the lower portion of said subassembly.

References Cited in the file of this patent UNITED STATES PATENTS 2,081,503 Nowosielski May 25, 1937 2,493,743 Benson Jan. 10, 1950 2,609,808 Bychinsky Sept. 9, 1952 2,741,716 Arthur et a1. Apr. 10, 1956 2,875,365 Pierce Feb. 24, 1959 FOREIGN PATENTS 112,752 Great Britain Ian. 24, 1918 206,665 Great Britain Nov. 15, 1923

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