US2591626A - Automatic gas igniter tube for burners - Google Patents

Description

April 1, 1952 s. A. SLOAN 2,591,626

AUTOMATIC GAS IGNITER TUBE FOR BURNERS Filed Dec. 17, 1948 s Sheets-Sheet 1 attorneg April 1, 1952 s. A. SLOAN 2,591,626

AUTOMATIC GAS IGNITER TUBE FOR BURNERS Filed Dec. 17, 1948 3 Sheets-Sheet 2 (Ittorneg Patented Apr. 1, 1952 UNITED STATES PATENT oFFrcE Annmarie; GAS IGNITER TUBE. FOR BURNERS StephemAi Sloan; Metuchen, N. 1., assignor to Peabody Engineering Corporation, New York, N. Y., acorporation of New York Application-Decemberfl'i, 1948, Serial'No. 655800 This invention relates to gas igniters" andmore particularly to an ignition-system having. auto-:' matic control means to supply purge air and gas: in correct sequence through the igniter 'tub'e and" to energize an ignition spark in proper timed" relationship to the passage of the gas.

The invention also providesa novel' an'd improved tip for an igniter which wil1=ignite" and retain its flame even with the blast of air through a burner tube.

An object of the invention is to provide an ignition system of the above type which operates.

automatically in proper timed sequence.

Another object is to provide a gas igniter of connected to an external line by. low tension" leads.

Various other objects and advantages will be apparent as the natureof the invention is-more fully disclosed.

Although the novel features which are'characteristic of this invention are pointed'out more particularly hereinafter, the nature of the invention will be better understood by referring to the following description, taken in connection with the accompanying drawings, in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawings:

Fig. 1 is a longitudinal section through atypical burner showing the igniter in oneposition for ignition;

Fig. la is a diagrammatic end elevation of the burner of Fig. 1 showing a representative orientation of the igniter tip in the burner air stream;

Fig. 2 is a side elevation of the igniter'on a larger scale with parts broken away to show the construction thereof;

Fig. 3 is a fragmentary elevational view of the igniter tip shown in Fig. 2;

Fig. 4 is a transverse section of the igniter tiptaken on the line 4-4 of Fig. 3;

Fig. 5 is a transverse sectional view taken on T the line 5-5 of Fig. 6 showing the arrangement 2 of the gas and air control valves and'th'eigniter switch;

Fig. 6 is alongitudinal section taken'onxthe line (i -13 :of Fig. 5;

Fig. 7 is acdetail view showing the position of the detent for locking thehandlein gas'supply' position; and

Fig.8 is a transverse section taken onlthe. line Referringv to the drawings moreiindetailpthel invention is shown as appliedto .a conventional fuel burner including a; burner: tub'e I ll through which the-combustion air'pass'es in :the form of a rotating mass: an air'register II? having; air' doors l2 through which.this:air is admitted-to the burner tube; a; front plate I3. at." the front ofth'e. wind box, a furnace wall'ltrhaving aithroat' I5: registering with the burne'rtube, a'fuel admission ring: lfi'located around the 'burnerftube l0;adjacentthe throat I5 andafuelato'mizer I1 which supplies: other fuel: for. combustion? The burnermay also beadapted to?burni pow-- dered" fuel? suspended; in' carrier air as is'iwell' known-:in the art.:

The-igniter; according tothe presentinvention;. comprises ar'body.2ll1(F.ig; 2) having an" axial passage'Z I and provided: at; one. end with-flanges 22-which1are secured-by bolts" 23? to a caStingPZA' (Figs; 2 and 8) carrying thei-controlelements to be described. At its other end the igniter body;

20*.carries aLpair' of 'ignitionielectro'des 25fon'e of which may be grounded to .the'body 2 0 by a' 'cap 26, and the other of whichmay be 'insulated by and;sup'ported in a spark. plug 2'l'which' is-"connected by a cable 28itothe high tension sidel of a transformer 29 which 'is mounted in al'housi ing ll'attached to the casting! or formed integral therewith; A sight glass 42: is shown as mounted in the bodyr2lJ'v over the: electrodes :25.

The electrodes; sightglass, cables, casting, transformerand associated parts are sealed"aga'inst the pressure in the wind box.

The, body; Zll, islalSoprovided with a coupling flange 30 in which'a tube "3 [of any desired' length is secured. The tube 3| is slidablezinaan outer.

tube -433which= extends through the front plate l3; asindicatedinl ig. 1, and projects atitszinnerend through the burner-tube Ill: .The: tube 3| extends through a stuffing box: l l': 'whichiis' secured tothe front plate l3 by bolts'45r and supports the outer tube 43; The tube 3| carries a tip 3 2 which is positionedwithin the-burner; tube. III. in the 'path, of the air-stream therein and adjacent the fuel streamstowbe' ignited.

The tip 32 is shown in the form of'a; flared 3 U-shaped housing 33 (Fig. 4) which is coaxial with the tube 3! and is closed at the two ends by plates 39. The flared side of the U-shaped member 33 is closed by a front plate 35 which is inclined to the axis of the U-shaped member 33 and of the igniter tube 3! and is provided with a central opening 36 through which the gas for combustion passes. The plate 35 is recessed from the extremities of the U-shaped member 33 and of the end plates 34 to form upstanding peripheral flanges 49 which extend entirely around the periphery of the plate 35 to shield the same from the blast of secondary air in the burner tube and to form eddy currents which serve to hold the igniter flame against the plate 35. The plate 35 is inclined in the direction of air flow towards the burner throat I so that the flame passing from the aperture 36 therein is directed towards the ignition zone of the burner. A lateral flange 48 extends outwardly from the side of the member 33 exposed to the rotating air stream and an end flange 4'! having an upstanding lip 49 is mounted on the end plate 39 towards the air register II. The U-shaped member 33 is preferably placed at such an angle with respect to the direction of air flow through the burner tube I9 that the air passes over the curved surface of the U-shaped member 33 so as to flow in a general direction from its closed end toward the open end thereof whereby the member 33 serves to deflect the air blast away from the igniter flame projecting from the aperture 36 and the flanges 49, 99 and 9! producing eddy currents to hold the "flame to the plate 35 and preventing its being blown out by the force of the air blast.

The casting 2 carries an air valve 59 and a gas valve 5!. The air valve 59 is shown as comprising a housing 52 which is secured in a transverse bore 53 in the casting 24. The valve housing 52 has a valve seat 55 and ports 56 to communicate with the transverse bore 53 of the casting 29. A valve plunger 5 registers with the seat 55 and is held in pressure engagement therewith by means of a spring 58 seated in a valve cap 9!. The valve plunger 5'! carries a pin 59 which is actuated by a cam disc 69 mounted in the transverse bore 53. The valve housing 52 is also provided with a passage 62 which registers with an air pipe 93 leading to a suitable source of purge air.

The gas valve 5! comprises a housing 68 having a Valve seat 79 and passages 'Il communicating with the transverse bore 53 of the casting 29. A valve plunger 12 registers with the valve seat '69 and is held in pressure engagement therewith by a spring I3 seated in a cap I5 threaded into the housing 68. The valve plunger 12 also carries a pin 19 which is actuated by the cam disc 69. The valve housing 98 is also provided with a passage FB communicating with a gas supply pipe I! through which combustible gas is supplied. The casting 24 also contains a passage 89 communicating with the igniter body 29 for the passage of air or gas thereto from the respective pipes 63 and TI.

The cam disc 69 is mounted on a shaft 8! which, as shown in Fig. 6, bears against a thrust bearing in the form of a ball 82, the thrust of which is taken up by a spring 84 seated in a boss 83 and formed in the casting 24. The casting 29 is also provided with a top flange 88' on which is mounted a switch housing 81. The shaft 8! extends through a bore in the switch housing 8? and is sealed by means of packing 89. A flange 99 attached to the shaft BI bears against the packing 89 and is held in sealing contact there with by the spring 84.

The cam disc 69 is provided around a portion of its periphery with an arcuate surface 93 which, in the position shown in Fig. 8, has a running clearance with the pins 59 and I4 so that the valve plungers 5'! and 12 remain seated. The disc 69 also carries a raised position 94 which is adapted to engage the pin 59 and raise the valve plunger 51 from the seat 55 at the beginning of the arc of movement of the disc 69 in a clockwise direction from the position shown in Fig. 8. It is to be noted that the raised portion 94 is of a shape to open and reclose the valve 59 during the first portion of the arc of movement of the disc 69.

The arcuate portion 93 of the disc merges into a raised portion which is positioned to engage the pin 14 for opening the valve 5! shortly after the valve 59 has been closed. The are of movement of the disc 69 starts at the position shown in Fig. 8 and extends to a position such that the raised portion 95 engages the pin 19 to hold the valve plunger I2 in full open position. Hence during the movement of the cam disc 69 from the position first shown, the valve 59 is first opened and then closed and the valve 5| is then opened and held in open position until the disc 69 is restored to its original position.

A microswitch I99 is mounted in the switch housing 8"! and is provided with an actuating arm I9! which engages a cam I92 mounted on the shaft 9i. portions !93 and I94 which are adapted to release the switch arm !9! for allowing the switch I99 to remain in open position when the cam I92 is at both ends of its normal arc of travel. The cam I92 is provided with a raised arcuate portion I95 between the recesses I93 and I99 which is adapted to shift the arm I 9! to a position to close the switch I99. The arrangement is such that the switch will be closed shortly after the shaft 9! begins to turn and remains closed until the shaft reaches practically the end of its arc of travel. Thereafter the switch I99 is opened.

The switch housing 3"! carries a cover I!!! on which an index plate H! is mounted. A spring H2 is disposed in the switch housing 9'! having one end secured by a screw II3 to the shaft 8! and the other end attached to a fixed pin H4. The spring I I2 is designed to hold the shaft 8! in its initial position and to restore the shaft to that position after it has been actuated and released.

A lead I8 connects the primary of the transformer 29 to the switch I99 and a low tension lead I9 extends from the switch I99 to a suitable source of current such as the usual volt supply.

A yoke H5 is attached to the projecting end of the shaft 3! by a pin H9. The yoke H5 carries a pointer II! registering with an index carried by the index plate Hi. The yoke also carries an operating handle E29 which is pivoted thereto by a pin I2! and is provided with an arm I22 which is held downwardly by a spring I23 seated in a recess I24 in the yoke I I5. The arm I22 carries a pin I25 which is held against the index plate I!!! by the spring I23 and when the handle I29 has been shifted to its extreme position enters a hole E2? in the index plate I I I. The index plate is shown in Fig. '7 as provided with an upstanding flange I28 adjacent the hole I2! to prevent the pin I29 from overriding the hole and passing the same. The arrangement is such that when the handle is shifted to its extreme posi-v The cam I92 is provided with recessed 5 tion, the pin I25 enters the hole I21 and locks the handle in that position. The handle may be released, however, by pressing downwardly, thereby compressing the spring I23 and withdrawing the pin I25 from the hole I21 whereupon the spring I I2 restores the handle and the shaft BI to its initial position.

Operation In order to start the ignition, the handle I20 is shifted gradually in a clockwise direction from the position shown in Fig. 2 to the extreme limit of its movement. As indicated by the index, the initial position of the handle I20 corresponds to the off position wherein both valves 50 and SI are closed and the switch I is open. During the first part of the movement of the handle I20, the valve 50 is opened to supply purge air from the pipe 63 to the igniter tube. At about the same time the switch I00 is closed to start the ignition spark at the electrode 25. Upon further movement of the handle I20, the valve 50 is closed to cut of? the supply of purge air and the valve I is opened to supply gas from the pipe 11, the ignition switch remaining closed. The ignition then takes place at the interface between the purge air and the gas where there is sufiicient air to initiate combustion regardless of variations in the B. t. u. content of the gas. The flame passes downwardly through the tube 3| with the gas and thence through the opening 36 in the plate 35 to burn adjacent the face of the plate 35 which,

as pointed out'above, is located in the air stream of the burner tube I0 where there is sufficient air present to complete the combustion. As the handle I26 is further advanced to its extreme position, the ignition switch I00 is opened to cut off the ignition spark so as to prevent carbonization at the electrodes due to long continued sparking, and the gas valve 5| remains in open position. The flame then continues to burn at the tip. The handle I20 is latched in this position by the pin I26, as above described, and may remain in this position until the burner I0 has become ignited. The handle I 20 may then be depressed to release the pin I26 and permit the spring II2 to restore the handle and the cams 50 and I02 to their initial positions thereby cutting off the ignition flame.

Since the flame is initiated at the electrodes and passes downwardly through the tube 3|, the tube may be of any desired length to carry the flame to the zone of combustion. Hence the body 20 and electrodes may be located in front of the front plate I3 and the tip may be located at a remote point in the burner tube as shown. Long electrodes and high tension insulators are thus eliminated. The tube 3| and tip 32 may be retracted into the outer tube 43 for protection when the igniter is not in use by sliding the body 20 in the stuffing box 44. If the tube 3I is to be entirely withdrawn from the tube 43, a check valve should be provided to prevent escape of the air from the wind box. The entire assembly may be removed by loosening the bolts 45 and withdrawing the inner and outer tubes from the front'plate I 3.

It is to be understood that the tip may be 7 located axially of the burner or may pass through the air register if desired. A specific location has been shown for purposes of illustration only.

In the construction above described, a stable flame is produced at the tip 32 which is not blown out by the blast of air through the burner tube I0. While the angular position of the tip in the burner tube I0 may be varied somewhat, the

best results are obtained when the closed end of the member 33 is pointed in the direction of air flow so that the air passes around the outside of the member 33. The flanges 40, 46 and 41 provide turbulence which retains the flame on the surface of the plate 35. Due to the difference in depth of the flange 40 around the different portions of the periphery of the plate 35, a proper degree of turbulence is maintained over at least one portion of the plate 35 to support combustion under the different conditions of use. In certain instances it may be desirable to mount the plate 35 in a plane parallel to the axis of the tube 3I or to form the flanges 40 of the same depth around the entire plate. The construction shown, however, has been found to operate satisfactorily over a wide range of burner conditions and to maintain a stable ignition flame even when the combustion air within the burner tube I0 is turned on suddenly. Due to the automatic control of the sequence of operation of the air and gas valves and of the ignition switch, a proper timing is always maintained for securing the best results without the variations which would be inherent in separate manual controls for the different elements.

The invention is particularly adapted for use with large size industrial burners although its application is not to be restricted thereto. The shaft 8| may be power-operated by a remote control if desired. The igniter is not to be restricted to use with a burner, but may be used in various instances where the initial ignition at the electrodes takes place under conditions to cause incomplete combustion and the air to complete the combustion is present at the tip. Hence the device is not dependent upon the heat content of the fuel supplied as sufiicient air for complete combustion is supplied at the remote tip.

Various changes and adaptations may be made in the various details of construction without departing from the scope of the invention.

What is claimed is:

1. A gas igniter comprising an igniter tube having a tip, a source of purge air and a source of combustible gas for ignition, ignition electrodes disposed in said igniter tube, a switch connected to control the supply of current to said electrodes. valves connected to control the passage of purge air and combustible gas from the respective sources to said igniter tube, and a timed control having means operable in timed sequence for actuating the purge air valve, the combustible gas valve, and the igniter switch so as to first purge the igniter tube with air, then supply combustible gas thereto and energize said ignition electrodes.

2. An igniter comprising a housingcarrying an igniter tube having a tip, a chamber in said housing communicating with said igniter tube, an air supply duct and a gas supply duct, a pair of valves oppositely disposed in said chamber, and adapted to control the communication between said ducts and said chamber, valve actuating pins operatively associated with each valve and projecting into said chamber, a rotary cam positioned in said chamber and having a cam surface positioned to engage said pins for the actuation of the respective valves, a shaft carrying said cam, and means rotating said shaft to actuate said valves, said cam being shaped to first open and close the air control valve and then to open the gas control valve.

3. An igniter comprising a housing carrying an igniter tube having a tip, a chamber in said housing communicating with said igniter tube, an air supply ductand' a gas supply duct communicat ing with said chamber, a pair of valves oppositely disposed in: said chamber and adapted to control the communication between said ducts and said chamber, valve actuating pins operatively associated with each valve and projecting into said chamber, a rotary cam positioned in said chamber and having a cam surface positioned to engage said pins for the actuation of the respective valves, a shaft carrying said cam, means rotating said shaft to actuate said valves, said cam being shaped to first open and close the air control valve and then to open the gas control valve, electrical ignition means operatively associated with said igniter tube, a switch to control said ignition means and a switch cam mounted on said shaft having means to actuate said. switch, said switch cam being shaped to close said switch during a period which overlaps the open periods of said air valve and of said gas valve and to open said switch in the other positions of said cam.

4'. An igniter comprising a housing carrying an igniter tube having a tip, a chamber in said housing communicating with said igniter tube, an air supply duct and a gas supply duct communicating with said chamber, a pair of valves oppositely disposed in said chamber and adapted to control the communication between said ducts and said chamber, valve actuating vpins operatively associated with each valve and projecting into said chamber, a rotary cam positioned in said chamber and having a cam surface positioned to engage said pins for the actuation of the respective valves, a shaft carrying said cam, means rotating said shaft toactuate saidvalves, said cam being shaped to firstopen and close said air control valve and then to open said gas con-- trol valve, electrical ignition means operatively associated with said igniter tube, a switch to control said ignition means, a switch cam mounted on said shaft having means to actuate said switch, said switch cam being shaped to close said switch during a period which overlaps the open periods of. said air valve and of said gas valve and to open said switch inthe other posie tions of said cam, spring means operativel-y associated with said shaft tending to restore said shaft to its initial position when released, and latching means positioned to latch said. shaft in its fully advanced position.

5. An igniter comprising a housing having a chamber therein, an unobstructed tube com municating with said chamber and having: a burnr tip at its end, an air ductand a gassupplyduct communicating with said chamber, control valves in the respective ducts, ignition electrodes in said tube at a point remote from said tip, a transformer mounted in said housing. having a secondary connected to said electrodes and having a primary connected to a low tension lead, a switch in said lead and means to actuate said switch and said valves in timed sequence for actuating the purge air valve, thecombustible of combustible gas for ignition, ignition electrodes disposed in said igniter tube, a switch; connected to control the supply of current to said electrodes, valves connected to control the passage of purge air and combustible gas from the respective sources to said igniter tube, and a timed control having means operable in sequence for actuating the purge air valve, the combustible gas valve, and the igniter switch for first purging, then supplying combustible gas and ignition, saidtip being remotely located with respect to said electrodes.

7. An igniter comprising a housing, anigniter tube having a tip, said tube being carried by said housing, a chamber in said housing communicating with said igniter tube, an air supply duct and a gas supply duct communicating" with said.

chamber, a shaft extending through said cham-. ber, a cam on said shaft rotating in said chamber,

- a pair of valves disposed on opposite sides of said cam adapted to control the communication be'-. tween said ducts and said chamber and having actuating pins positioned to engage said cam at diametrically opposite points, a switch housing attached to said first housing, saidshaft extending through said switch housing and carrying a cam to rotate in said switch housing, and switch means in said last housing actuated by said last cam.

8. In an igniter, as set forth in claim '7, packing means around said shaft sealing said chamber from said last housing, a collar on said shaft to engage said packing means and spring means holding said collar in sealing engagement with said packing means.

9. In an igniter, as set forth in claim 7, an actuating handle on said shaft and spring means to restore said shaft to its initial position after actuation by said handle.

10. An igniter comprising a housing having a chamber therein, an unobstructed tube communicating with said chamber and having a burner tipat its end, an air duct and a gas supply duct communicating with said chamber, control valves in the respective ducts, ignition electrodes in said tube at a point remote from said tip, a switch connected to control the supply of current to said electrodes, and means to actuate, said switch and said valves in timed sequence for" actuating' the purge air valve, the combustible gas valve, and the igniter switch so as" to first purge the igniter tube with air, then supply combustible gas thereto and energize said ignition electrodes for thereby starting ignition at the zone of said electrodes and causing the flame totravel to said tip.

STEPHEN A. SLOAN.

REFERENCES CITED The following. references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,810,957 Fraser June 23, 1931 2,152,531 Browning a-.. Mar. 28,' 1939 2,212,375 Camp ..e Aug. 27, 1940 2,276,751 Weber Mar. 17,1942 2,332,210 Frank Oct. 19, 1943 2,460,016 Kuhn Jan. 25, 1949 2,510,482 Sch'arbau et al June 6, 1950

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