US2859590A - Piston type igniter - Google Patents

Description

United States Patent PISTON IGNITER Richard J. -Masom, Lyndhnrst, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware This invention concernsigniters for fuel-air type combustion chambers. It is particularly concerned with a novel and useful piston type igniter that is of advantage in facilitating ignition, particularly cold temperature ignition.

The device is characterized by a piston which is adapted, under pressure of air applied to it, to drive fuel from a chamber of the device through a nozzle to sparking electrodes provided at an end of the device.

This igniter finds particular use in association with the combustion chamber of hot gas turbine type engine starters in effecting eflicient ignition in the latter under adverse temperature conditions.

A general object of the invention is, therefore, to provide an improved fuel air combustion chamber igniter to facilitate ignition, particularly cold temperature ignition.

A further object of the invention is to provide a novel and useful piston type igniter wherein volatile fuel is driven from a chamber of the igniter to sparking electrodes by a piston.

The invention further lies in the particular construction thereof and in the general organization and cooperative association of its various elements.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawing wherein an embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for illustration purposes only and is not to be construed as defining the limits of the invention.

The drawing is a longitudinal section through a piston type igniter embodying the invention.

Reference is directed to the drawing, wherein there is disclosed a piston type igniter plug embodying the invention, and comprising an outer shell 1 and an inner shell 2, both of electric conductive material and insulated from one another by a suitable non-conductive material, such as a nylon shell 3. Shell 2 is closed over at its left end by a conductive plug 4 which is sealed against leakage by a suitable sealing ring 5 in a peripheral channel thereof. A stud 6, extending from the left face of the plug to the outside through a neck 7 of the nylon shell 3, serves as an electrode on which is connectable the terminal 8 of a conductor 9. The latter is in connection with a suitable igniiton box, not shown. Terminal Sis secured between a conductive lock nut 10 and an insulator washer member .11.

The inner shell 2 provides a chamber 12 in which is slidable a piston 14. The chamber is elongated and is intended to hold at the right of the piston a supply of combustion fuel admitted through a port 15 connected to a conduit 31 controlled by a valve. This fuel is subject to being driven out of the chamber by pressure air admitted through a port 16 connected to a conduit 32 controlled by a valve to the chamber at the left of the piston. The fuel is driven in a fine relatively flat conical spray out of a proper nozzle 17 having a suitably slotted 2,859,590 Patented Nov. 11, 1958 2 ball 33. Nozzle 17 is threaded into ashort open neck portion 18 at the right end of inner shell 2. Intermediately of the nozzle and the fuel end of the chamber is properly fitted a check valve 19, which is retained in position by a shoulder 20 at the right and a snap ring '21 at the left. A conventional check valve spring 22 nor-; mally holds the conical valve member 34 shut, prevent ing fuel from passing through; the slotted ball 33 and nozzle 17 until suchtime as pressure air is applied to the left face of the piston.

The outer shell 1 ofthe deviceis electrically grounded. A surface gap spark plug to ignite fuel sprayed out of the nozzle is providedby the relation of an end face 23 ofa peripheral end flange 24. of;.the nozzle and an end face 25 of a radial inwardly extending flange 26 at the right end of the outer shell 1. Nozzle flange 24 is short and overlaps the end wall of the neck 18 of shell 2, and its periphery is spaced bya .gap' from the opposed-inner diameter of the outer shell flange 26. The gap isfilled by a short neck end of a porcelain insulator 27 which surrounds the neck 18 of shell 2 and is retained in position by a shoulder of shell 2 on its left and the inner face of flange 26 at the right. The outer periphery of the insulator contacts the inner wall of shell 1. The end face 23 of the nozzle is flush with the end face 25 of the outer shell and with the exposed end of the porcelain insulator 27. The spaced coaxial faces 23 and 25 provide a pair of sparking electrodes for the device. When a surge of current from the ignition system, which is preferably a low tension system, is passed through the device by way of the conductor 9 to the inner shell 2 and the nozzle 17, high energy sparking occurs across the gap as the current sparks over the latter to the grounded shell 1.

Sparking occurs about the gap in a whirling or random fashion. This construction provides a high energy spark for igniting a flat highly volatile fuel spray passing over the sparking electrodes as the spray issues conically from the nozzle of the device.

The device serves as a flame igniter for combustion chambers operating on fuel and air, and it has particular advantage in facilitating cold temperature ignition through the use of volatile fuels.

In the drawing, the wall 28 represents the shell of a combustion chamber, which may be that of a hot gas turbine starter, or other device. The sparking. end of the device is inserted through the combustion chamber shell 28 of the combustion chamber. It is secured in this position by a peripheral flange 29 that is mounted to the outer surface of shell 28. To facilitate assembly of the various elements of the device, the outer shell 1 is preferably formed of two separable parts united to one another by opposed mating flanges 29 and 30. The flange 29 serves to secure the position of the device to the associated combustion chamber, and the location of the flange may be utilized to serve as a stop to predetermine the proper distance that the sparking end of the device is to be inserted into the particular combustion chamber with which the device is to be associated.

Although an embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes may also be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art, and it is my intent, therefore, to claim the invention not only as shown and described, but also in all such forms and modifications as may reasonably be construed to be within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. The combination comprising an outer conductive shell having an annular end face providing one member I of a pair of sparking electrodes, an inner electrical .conductive shell insulated from said outer shell and having an annular end face providing the second member of the electrodes, said annular end faces being spaced to provide a sparking gap separating the electrodes, a piston slidable in a chamber provided by the inner shell, means connected to said chamber for admitting volatile ;fuel to the chamber to the inner side of the piston, a nozzle having an exitsurrounded by the electrodes, and means connected to said chamber for=admitting pressure air to the chamber at the opposite other side of the piston to effect movement of the latter to drive the fuel-through he nozzle exit.

2-. In the combination set forth inclaim 1, wherein the nozzle is a continuation of an end of the inner shell and provides the second member of the electrodes.

3. In the combination set forth in claim 1, wherein the sparking gap is filled by a porcelain insulator.

4. In the combination as in claim 1, wherein the electrodes have and faces flush with one another and flush with an end face of an insulator filling the gap between them. i

5. In the combination as in claim 1, wherein the fuel spray issued by the nozzle is conical and passes angularly over the surrounding electrodes due to the construction of the nozzle and the arrangement of the nozzle exit and the electrodes.

6. A piston type igniter comprising a conductive housing, an insulator liner, an inner conductive liner separated by the insulator from the housing, an annular electrode at one end of the inner liner, an annular insulator separating the electrodes, a volatile fuel chamber provided by the inner liner and having means to admit fuel, a nozzle providing an exit from said chamber coaxial with the electrodes and a piston movable in the chamber for forcing the fuel .from the chamber through the exit.

References Cited in the file of this patent UNITED STATES PATENTS 2,279,546 Ziegler Apr. 14, 1942 2,574,495 Parker Nov. 13, 1951 2,731,079 ,Smits Jan. 17, 1956

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