US3088282A

US3088282A - Ignition apparatus

Info

Publication number: US3088282A
Application number: US609877A
Authority: US
Inventors: James J Logan
Original assignee: Bendix Corp
Current assignee: Bendix Corp; Unison Industries LLC
Priority date: 1956-09-14
Filing date: 1956-09-14
Publication date: 1963-05-07
Anticipated expiration: 1980-05-07

Description

y 7, 1963 J. J. LOGAN 3,088,282

IGNITION APPARATUS Filed Sept. 14, 1956 4 x it 7 44 26 i k1 A 6? M 5g 42 22 Y 39 as 46 A I 48' I 11 INVENTOR. I 67 JAMES J. LOGAN 7/ i 6 i 8 BY 74 77 l '4 5 77 5 MI/ /2 52 ATTORNEYS United States Patent 3,088,282 IGNITION APPARATUS James J. Logan, Unadilia, N.Y., assiguor to The Bendix Corporation, a corporation of Delaware Filed Sept. 14, 1956, 52:. No. 609,877 3 Claims. (Cl. 60-3932) This invention relates to fuel injection and ignition apparatus and more particularly to a combined spark gap and fuel nozzle for torch ignition systems. The apparatus of the invention is useful, for example, in socalled jet or turbine engines.

One of the objects of the present invention is to provide a novel combination of a spark gap and fuel nozzle in closely spaced relationship in a unitary assembly.

Another object of the invention is to provide a simplified combined spark gap and fuel nozzle assembly of light-weight construction, the spark gap and fuel nozzle being readily removable as a unit, and thus easily serviced or replaced.

Still another object is to provide a novel torch ignition system wherein the spark gap and fuel nozzle are disposed in a symmetrical relationship close to each other.

Another object is to provide a combined spark gap and fuel nozzle device characterized by its compactness and the economy of its manufacture and maintenance.

Still another object is to provide a unitary device having a combined spark gap and fuel nozzle, the device being of such construction as readily .to provide an electrically semi-conductive body connected to shunt with the electrodes of the spark gap.

The above and further objects and novel features of the invention will more fully appear from the following description when the same is read in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for the purpose of illustration only and is not intended as a definition of the limits of the invention.

In the drawing wherein like reference characters refer to like parts throughout the several views,

FIG. 1 is a longitudinal axial section through one form of device having a combined spark gap and fuel nozzle in accordance with the invention, certain parts of the device being shown in elevation,

' FIG. 2 is a view in longitudinal axial section through the nozzle assembly of the device of FIG. 1, and

FIG. 3 is a longitudinal section through the insulating body which positions the fuel nozzle at the inner end of the device.

The embodiment of the invention illustrated in the drawing, by Way of example, is in the form of a torch ignition device adapted to be mounted in an opening in the wall of the combustion chamber of a jet or turbine engine. The inner end of the device, shown at the bottom in FIG. 1, is then in communication with the combustion chamber of the engine, the outer end of the device, shown at the top in FIG. 1, extending outwardly beyond the outer wall of the engine. The ignition device may either be operated continuously, by continuously introducing fuel thereto while energizing the spark gap, or may be operated only intermittently as in the starting of certain types of engines in which combustion is selfsustaining.

The device in .the embodiment shown has an elongated shell made of strong electrically conducting material such as alloy steel. The shell has a circular cylindrical upper portion, a downwardly converging, conical intermediate portion adapted to interfit with the passage through the wall of the combustion chamber of .the engine, and an inner circular end of smaller diameter. The shell is retained on the engine by means of a mounting flange 3,088,282 Patented May 7, 1963 11 secured as by welding to the outer end of shell 10. The inner end of the device carries a combined gap and fuel nozzle assembly, generally designated 12, to which electrical current is delivered by means to be described from a lead wire having a connector 14 attached to the device. Fuel for the nozzle is delivered to the device by a conduit (not shown) connected to passage 32 through the wall of shell 10 near the outer end of the shell and outwardly of the combustion chamber.

Coaxially positioned within the central opening in shell 10 is an elongated member 16 which functions as the current lead to the central electrode of the spark gap of the device, and as :a portion of the means conducting fuel to the nozzle. Member 16 is spaced from the inner wall of shell 19 by means of electrically insulating spacer sleeve 17, which may be made, for example, of Teflon. Sleeve 17 has an outwardly thickened upper end 19 which sealingly engages the inner wall of shell 10 and a portion of the outer surface of member 16, the enlarged upper end of the sleeve resting upon internal shoulder 20 on the shell. Member 16 is supported at its outer end by means of a large insulating washer 21 which is seated in counterbore 22 in the outer end of shell 10.

Washer 21, which may be made of a hard molded resin material, retains member 16 in the desired angular position, the washer being keyed to the shell by having radial projection 24 on the former received in a radial recess in the outer end of the shell, and by the reception of the radially outer end of cross pin 26 through the shank 25 of member 16 in the longitudinally extending slot 27 in the wall of the bore through the washer 21. The outer end of shank 25 of member .16 is threaded at 29, the shank carrying an inner nut 30 forcibly engaging washer 21, and an outer nut 31, the electrical connector 14 being gripped between such nuts.

Fuel for the nozzle is led into shell '10 through radial opening 32 through the wall of the shell and thence through openings or ports 35 through the wall 18 of member 16 into the longitudinal central bore in such member. Communication between the pass-age 32 and the ports 35, as well as the electrical insulation of the upper portion of member 16 from shell 10, are provided by an inner electrically insulating sleeve 36 which intimately surrounds member :16 at a zone including ports 35, by an outer grooved spacer and packing member 38 which surrounds and intimately engages sleeve 36 and closely fits within the bore in shell 10, and by upper and lower preformed

annular packing members

39 and 40, which are interposed between the shell 10 and the sleeve 36, and are disposed, respectively, between the upper end of sleeve 38 and the lower end of washer 21, and between the lower end of sleeve 38 and the upper end of sleeve 17. Member 36 may be, for example, a molded laminated phenolic resin material; member 38 may be made, for example, of Teflon. 'Ihe thus formed composite electrically insulating and sealing structure made up of

members

36, 38, 39 and 40 provides an annular chamber surrounding member 16 at ports 35 and communicatingwith passage 32.

The construction of the nozzle assembly, generally designated 41, which is mounted upon the lower end of member :16, will be more fully understood by consideration of FIG. 2. The nozzle assembly has a main tubular body 42, said body having on its outer end external threads 44 which are received in the internal threads 45 on the inner end of wall 18 of member 16. A strainer member 46, having a cylindrical strainer sleeve 4-7, has an inner flange 49 thereon clamped between the end of a counterbore at the lower end of body v16 and the outer end of body 42 of the nozzle. Member 42 has a central cylindrical passage 50 therein, passage 50 terminating at an inner sharply converging conical end wall 5 1 which 3 communicates with a central nozzle orifice 52. Centrally positioned in passage 50 is an elongated nozzle pint-1e 54 having an inner cylindrical flange 55 thereon engaging wall 50 immediately above end 51. The body mem:

ber 54 has a diameter somewhat less than that of bore 50.

through member 42 so that a narrow elongated annular channel is presented between the pintle member and the wall of the bore 50. At the inner end of member 54 there is a shallow centrally located chamber 56 open to orifice 52, said chamber communicating with said narrow annular channel through two oppositely disposed generally tangentially disposed passages 57 (one shown).

Pintle ember 54 is maintained in position bottomed in the bore 50 against end wall 51 by a threaded hollow insert sleeve 60 received in the outer internally threaded portion 61 of member 42 to maintain tight engagement between the pintle member and the insert sleeve, a spring washer 62 being disposed between such members. The outer end of pintle member 54 is diametrically slotted at 59 to afford communication between the annular channel around the pintle member and the central passage formed by the bores through the outer end of member 42 and the insert sleeve 60. When the nozzle member is assembled in the unit as shown in FIG. 1, fuel under pressure flows through passage 32, inwardly through ports 35 in walls 18 of member 16, thence longitudinally of the central passage in member 16, inwardly through the screen 47, through central passage 48 in flange member 49, and thence through the above described passages in member 42 to orifice 52 of the nozzle. Below the orifice 52 the nozzle is provided with an inwardly flared hood 64 to protect the spark gap from contact with the fuel issuing from orifice 52.

The inner end of body 42. of the nozzle assembly is provided with an outwardly directed flange 65, the outer edge 66 of which is of a somewhat enlarged diameter. Such flange portion 66 forms the inner electrode of the spark gap.

A ceramic insulator 67, made, for example, of fused alumina, surrounds and is aflixed to the inner end of body 42 in the assembled device. As shown in FIG. 1 such insulator has internal threads 69 engaged with external threads 70 on body 42 located outwardly of flange 65 thereon. The insulator '67 cooperates with a removable cap .71 which is attached to the inner end of shell so as to hold the nozzle coaxial of the shell. In the construction shown, insulator 67 also serves as a support for an electrical semiconductive layer 80 which is connected in shunt between the inner electrode 66 and the outer electrode of the spark gap, such outer electrode being formed by the radially inwardly projecting flange 76 on the end of cap 71. Insulator 67 is retained in the cap by means of an insert sleeve or ring 75 which has threaded engagement with internal threads on the cap, ring 75 overlying the larger diametered, flanged inner end 74 of the insulator.

Semi-conductive layer 80 may be made of a number of materials known for that purpose, and in a variety of manners. One such layer which has proved to be satisfactory is that disclosed in the patent to Harris, No. 2,953,704, issued September 20, 1960.

The thus described combined spark gap and fuel nozzle device may be assembled as follows:

The parts of the nozzle are first assembled in the manner shown in FIG. 2. Ceramic insulator 67 is then placed in cap 71 and is retained therein by ring 75. The nozzle assembly of FIG. 2 is screwed into ceramic insert 67. Sleeve member 36 is cemented to member 16 to form a seal between them. Screen 47 is placed in member 16 within tubular portion 18, and the above-described nozzle assembly is then screwed into the end of member 16. A wrench is applied to flatted portions 42' on member 42 to allow the nozzle assembly to be tightened into member 16 to form a seal with the flange 49 of the screen.

Insulating sleeve 17 is then inserted in body 10, sealing

members

40, 38, and 39 are inserted in that order into shell 10 above the end 19 of sleeve 17, and the washer 21 is mounted in the counterbore at the outer end of shell 10. The assembly of the nozzle 41, cap 71, and member 16 is then inserted in the inner end of shell 10 and is thrust into the fully assembled position shown in FIG. 1. Nut 30, applied to threaded shank .29 of member 16, pulls the internal assembly axially outwardly of the shell and insures a tight seal between

members

19, 20, 40, 38, 39, and 21. The internal assembly made up of the member 41 and the member 18 are thus held under longitudinal tension between flange 66, which abuts insulator 67, at the bottom and the nut 30 and the washer thereheneath, the latter abutting insulator 21. The housing or tubular shell 10 is thus held under compression between the flange 66, insulator 67, and cap 71 on the bottom end thereof and the insulator 21 on the top end thereof.

Threads 73 at the end of cap 71 are partially ground off on a taper, as shown in FIG. 1. The resulting internal lands on cap 71 forcibly engage the outer surface 72 on shell 10, such outer surface being tapered in the same direction and at least generally the same angle as the taper of threads 73, so as to center the cap on the shell and maintain the cap and shell from relative rotation.

The combined spark gap and fuel nozzle of the invention is of advantage because of its compactness, economy of parts, and ease of installation and substitution, if necessary. The current lead to the central electrode is formed by the conduit which feeds fuel to the nozzle, so that only one part need be provided to perform these two functions. The annular spark gap formed between surface 77 on flange 76 and surface 79 on flange 66 surrounds, and is centrally located with respect to, orifice 52 of the fuel nozzle. Such symmetrical disposition of the spark gap and fuel nozzle, as Well as their location close to each other, promotes efficient and fast ignition of the fuel, which is usually a liquid although it may be gaseous, if desired.

Although one embodiment of the invention is illustrated in the drawing and described in the foregoing specification, it is to be expressly understood that the invention is not limited thereto. For example, although the spark gap shown and described is of the high energy, low voltage shunted gap type, the gap, if desired, may be of the high voltage unshunted type. The device of the invention may be used, tor example, as a starter for the main burner of a turbine or jet engine, or it may be used to carry all the fuel to the engine of a turbine type starter. Various changes may also be made in the design and arrangement of the parts illustrated as well as in the materials thereof herein suggested as suitable without departing from the spirit and scope of the invention as it will now be understood by those skilled in the art.

What is claimed is:

1. Tomb ignition apparatus comprising an elongated metal casing having a central passage longitudinally therethrough, said casing having an inner end adapted to project into a combustion chamber and an opposite, outer end adapted to be positioned outwardly of the combustion chamber, said casing having an annular shoulder projecting inwardly from the wall of the passage intermediate the length of the casing, an elongated metal member centrally disposed within the casing, a first sleeve of electrically insulating material surrounding the elongated member at the shoulder and extending on both sides thereof longitudinally of the casing, said first sleeve snugly engaging the casing and the elongated member and having an outwardly extending flange overlying and engaging the shoulder on the casing, the elongated member at its outer end having a cylindrical portion of reduced diameter overlapping the flange on the first sleeve, a second electrically insulating sleeve snugly engaging the outer reduced diameter portion of the elongated member and having its inner end telescop'ed within the outer end of the first sleeve, a longitudinally extending central bore in the elongated member extending throughout a substantial portion of the length thereof from the inner toward the outer end of the elongated member, a nozzle on the inner end of the elongated member communicating with said bore, means to supply the nozzle with fuel comprising a transverse passage through the Wall of the casing, the second sleeve, and the wall of the elongated member into the bore therein, and an annular spark gap comprising a first, inner annular electrode on the inner end of the elongated member and a second, outer annular electrode on the inner end of the casing.

2. Apparatus as defined in claim 1, wherein the fuel supply means comprises an annular electrically insulating member interposed between the casing and the second sleeve at the location of said transverse passage, a transverse opening through said annular insulating member constituting a portion of said transverse passage, annular sealing means interposed between the casing and the second sleeve at both ends of the annular insulating member, and means to subject the sealing means to substantial axial compression.

3. Torch ignition apparatus comprising an elongated metal casing having a central passage longitudinally therethrough, said casing having an inner end adapted to project into a combustion chamber and an opposite, outer end adapted to be positioned outwardly of the combustion chamber, an elongated metal member centrally disposed within the casing, the inner end of the member carrying a nozzle lying adjacent the inner end of the casing, the nozzle carrying a first electrode of a spark gap located at the inner end of the casing, a second electrode of said spark gap being carried by and making electrical connection with the inner end of the casin g, means for electrically insulating the member from the casing comprising an electrically insulating sleeve surrounding the elongated member Within the casing, the casing having a counterbore in at least a portion thereof confronting said sleeve, a relatively stiff resilient electrically insulating ring-like member snugly interposed between the sleeve and the wall of the counterbore of the casing, annular sealing means interposed between the wall of the counterbore and the sleeve and sealingly engaged therewith and with the ends of the ring-like member, means to place the annular sealing means and the ring-like member in axial compression, and means to supply the nozzle with fuel, said last named means comprising a longitudinally extending passage Within the elongated member leading to the nozzle, and a transverse passage extending through the side wall of the casing, through the ring-like member, and through the side wall of the elongated member into the longitudinal passage therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,210,668 Meyer Jan. 2, 1917 2,255,203 Wiegand Sept. 9, 1941 2,572,209 Smits Oct. 23, 1951 2,574,495 Parker Nov. 13, 1951 2,684,665 Tognola July 27, 1954 2,859,590 Masom Nov. 11, 1958 FOREIGN PATENTS 619,354 Great Britain Mar. 8, 1949 621,789 Great Britain Apr. 20, 1949 738,966 Great Britain Oct. 19, 1955 OTHER REFERENCES Lodge I'gniters for Gas Turbines, published in the Oil Engine and Gas Turbine, March 1955, pp. 435 and 436, copy in Div. 18.

Claims

1. TORCH IGNITION APPARATUS COMPRISING AN ELONGATED METAL CASING HAVING A CENTRAL PASSAGE LONGITUDINALLY THERETHROUGH, SAID CASING HAVING AN INNER END ADAPTED TO PROJECT INTO A COMBUSTION CHAMBER AND AN OPPOSITE, OUTER END ADAPTED TO BE POSITIONED OUTWARDLY OF THE COMBUSTION CHAMBER, SAID CASING HAVING AN ANNULAR SHOULDER PROJECTING INWARDLY FROM THE WALL OF THE PASSAGE INTERMEDIATE THE LENGTH OF THE CASING, AN ELONGATED METAL MEMBER CENTRALLY DISPOSED WITHIN THE CASING, A FIRST SLEEVE OF ELECTRICALLY INSULATING MATERIAL SURROUNDING THE ELONGATED MEMBER AT THE SHOULDER AND EXTENDING ON BOTH SIDES THEREOF LONGITUDINALLY OF THE CASING, SAID FIRST SLEEVE SNUGLY ENGAGING THE CASING AND THE ELONGATED MEMBER AND HAVING AN OUTWARDLY EXTENDING FLANGE OVERLYING AND ENGAGING THE SHOULDER ON THE CASING, THE ELONGATED MEMBER AT ITS OUTER END HAVING A CYLINDRICAL PORTION OF REDUCED DIAMETER OVERLAPPING THE FLANGE ON THE FIRST SLEEVE, A SECOND ELECTRICALLY INSULATING SLEEVE SNUGLY ENGAGING THE OUTER REDUCED DIAMETER PORTION OF THE ELONGATED MEMBER AND HAVING ITS INNER END TLESCOPED WITHIN THE OUTER END OF THE FIRST SLEEVE, A LONGITUDINALLY EXTENDING CENTRAL BORE IN THE ELONGATED MEMBER EXTENDING THROUGHOUT A SUBSTANTIAL PORTION OF THE LENGTH THEREOF FROM THE INNER TOWARD THE OUTER END OF THE ELONGATED MEMBER, A NOZZLE ON THE INNER END OF THE ELONGATED MEMBER COMMUNICATING WITH SAID BORE, MEANS TO SUPPLY THE NOZZLE WITH FUEL COMPRISING A TRANSVERSE PASSAGE THROUGH THE WALL OF THE CASING, THE SECOND SLEEVE, AND THE WALL OF THE ELONGATED MEMBER INTO THE BORE THEREIN, AND AN ANNULAR SPARK GAP COMPRISING A FIRST, INNER ANNULAR ELECTRODE ON THE INNER END OF THE ELONGATED MEMBER AND A SECOND, OUTER ANNULAR ELECTRODE ON THE INNER END OF THE CASING.