US 2412655 A
Description (OCR text may contain errors)
Dec. 17, 1946. E, H, SHANNON I 2,412,655
IGNITION DEVICE ELE... l..
` BY' Z Y Dec. 17, 194e. E H, SHANNON '2,412,655
IGNITION DEVICE Filed sept. so. 1944 2 sheets-sheet 2 INVENTOR EARL /z SHAA/NUA;
Patented Dec. 17,
TED STATE PATENT orrlca f 2,412,655 rourrrounnvrca Earl E. Shannon, Gary, Ind.
Application September 30, 1944, Serial No. 556,588
This invention relates to ignition devices and more particularly to those whichv are operated electrically and used in connection with fuel burners.
It i's common practice to provide electrical ignition devices for fuel burners so as to maintain a continuous spark whereby temporary failures in the fuel supply system will not cause explosions upon resumption of the fuel supply after such failures. An ignition device for such purpose is shown in the patent to Miess No. 2,318,408. dated May 4, 1943. Such an ignition device as shown therein consists generally of a longitudinally extending burner having a single electrode spark plug arranged in an opening intermediate the length thereof to which current is supplied from a suitable source of power. There is connected to the inner end of the center electrode of the spark plug, an elongated electrode which extends substantially perpendicular thereto and is arranged axially of the burner.y n the other end of the burner there is arranged a grounded electrode at which point the spark is produced fory igniting the gases issuing forth from the outer end of the burner.
A similar ignition device is shown in my co pending application, Serial No. 518,269, led Jan uary 14. 1944, and entitled Spark plug.
- In `oth of the above devices the ground electrode is arranged outside of the burner in the furnace, the elongated electrode extending through the burner to a point adjacent the ground electrode, thus forming a spark gap. Thus the electrodes are exposed to the heat of the furnace and in a relatively short time must be replaced. This is especially true of the ground electrode which has no means for adjustment. The burner also makes considerable noise when operating, which I have found is due to the dis position of the ground electrode in the fuel stream.
It is an object of my'invention to provide an ignition device for burners in which the electrodes are protected from the heat of the furnace.
Another object is to provide an arrangement of electrodes in a tubular burner so that the noise or howl or the burner is mui'ied.
These and other objects will be more apparent after referring to the following specification and attached drawings, in which:
Figure 1 is a sectional view through the burner;
Figure 2 is an end view thereof; and
Figure 3 is a general arrangement of the and tube assembly.
Referring more particularly to the drawings burner 2 Claims. (Cl. 175-115) the numeral 2 designates a metallic fuel feed tube having the usual inlet end 2a and outlet end 2b, the latter of which is adapted to extend Within the`furnace or the radiant tube assembly with which the device of the invention is to operate. At the inlet end '2a of the fuel feed tube 2 there is provided the usual means 3 for' supplying gas together with an air inlet d.
In the side wall of the fuel feed tube 2 there is a screw-threaded aperture 5 which is adapted to receive the externally screw-threaded housing 6 of a conventional spark plug from which the ground electrode has been removed. Within the spark plug housing 6 vthere is disposed in screwthreaded engagement therewith the spark plug sleeve l which is adapted to' hold in rigid rela-l tionship therein the porcelain insulator 8 of the spark plug, the center electrode l B extending therethrough and well'into the center of the fuel The extended end of the center electrode d is screw-threaded and carries thereon an internally screw-threaded sleeve l@ which has a cross-aperture l2 therein. This cross-aperture l2 receives an elongated electrode i3 which projectsvfrom the exit end 2b of the fuel feed tube 2. The exit end 2b of the fuel feed tube 2 is pro-f vided with a refractory cap |41 having a series of apertures it therein, one of which is centrally disposed to receive the extended end of the electrode IB, which does not pass completely through the cap lf3. This refractory cap lil is suitably retained in the end of the fuel feed tube 2 by means of a screw-threaded retainer cap i6 which is threaded to the end of the extension sleeve il, this sleeve being provided with a ground electrode i8 similar to that of'a conventional spark plug. If desired the electrode IB can be fastened directly to the burner -body and the sleeve ll omitted.
Immediately opposite the screw-threaded aperture E in the fuel feed tube 2 is a similar aperture i9 in which there is disposed a screw-threaded plug 20. By. removing the screw-threaded plug 2d and loosening the externally-threaded sleeve l of the spark plug the porcelain insulator may be rotated to rellevethe set-screw eect of the electrode 9 with respect to the electrode i3 whereby the latter may be suitably adjusted. After the desired adjustment the porcelain insulator d may be rotated to again obtain the set-screw effect of the electrode 9 with respect to the electrode i3 and the externally-threaded sleeve 1 drawn tight to maintain the adjustment.
From the foregoing it will be seen there is provided 'a spark gap directly in the pathof the atmetel xuel stream wherein electrodes I3 and I8 defining said spark gap are disposed entirely within the burner in such a manner as to be removed from intimatecontact with the flame and protected from the heat of the furnace tube. By virtue of the described arrangement the electrodes do not deteriorate from use and as a result the required spark gap is constantly unvariably maintained providing efllcient ignition of the combustible gases with minimum adjustment and maintenance.
Referring to Figure 3 which shows a typical burner installation in which a radiant tube as sembly 22 is fastened to and passes through the wall 24 of a furnace, attention is directed to the striking similarity in shape and contour of the tube assembly 22 to a tone chamber of an ordinary musical instrument. In this instance the fuel emitting from the burner produces audible noise which is increased by the myriad minute explosions occurring during combustion.
In prior art practice it is customary to provide a spark gap for ignition purposes on the outside of the burner directly in the exiting fuel stream, and in such arrangements the grounded electrode forms an obstruction which disturbs the equilibrium of the fuel stream and creates additional noise.
The complexity of noises so created, and substantially amplified by the tone chamber, cannot be properly identified with known musical tones and possesses no acoustic characteristic except that of obnoxiousness. The volume of noise as well as its tonal quality is also effected by the pressure applied to the burner, the location of the burner, and other variables too numerous to mention.
By relocating the grounded y electrode I8 as shown in Figure 1 within the burner, it has been found that objectionable noises formerly present have practically disappeared, or at least have been altered in pitch or vibration frequency so as to Ibe no longer audible. This phenomenon may be partially accounted for by the fact that the combustible mixture is already in a turbulent 45 state within the discharge end of tube 2 caused rby the haine effect of refractory cap I4 which obstructs somewhat the flow 'of the mixture. It has been pointed out that the primary audible noises occurring outside of the burner are caused to increase in magnitude by the ground electrode located in the same vicinity, but by relocating the electrode within the yburner and adjacent the refractory cap I4 as shown, there -is no noise creating effect on the fuel stream.
While I have shown and described one specific embodiment of my invention, it will be under.
stood that 'I do not wish to be limited exactly thereto since various modifications may be made within the scope of my invention, as defined by the following claims.
l. In an ignition device for use with a tubular burner having a. perforated refractory cap on itsv discharge end, the combination which includes an electrode disposed within and extending longitudinally of the burner, said electrode being supported by and terminating in said refractory cap, a ground electrode disposed within the l'burner and located within two inches of said reits discharge end, the combination which includes EARL H. SHANNON.