US2261458A - Control system - Google Patents

Description

Nov. 4, 1941. E, G. BAILEY ETAL 2,

common SYSTEM I Filed Nov. 7, 1939 4 Sheets-Sheet l 3iwentor5 and ERVIN .G. BAILEY PAUL S; DICKEY' I Nov. 4, 1941. E. .G. BAILEY EIAL 2,261,458

CONTROL SYSTEM Filed Nov. '7, 1939 4 Sheets-Sheet} 52 FIG. '6

F| G 4 3nnentors ERVIN s. BAILEY By PAUL s. DIQKEY Nov. 4-, 1941. E. cs. BAILEY EI'AL CONTROL SYSTEM Filed Nov. 7, 1939 4 Sheets-Sheet 4 FIG. IO

3maentors FIG; 9

and ERVIN G: BAILEY PAUL S DICKEY Gttorneg Patented Nov. 4, "1941 CONTROL SYSTEM Ervin G. Bailey, Easton, Pa., and Paul S. Dickey, Shaker Heights, Ohio, assignors to Bailey Meter Company, a corporation of Delaware Application November 7, 1939, Serial No. 303,334

' 2 Claims.

mined number of attempts by the igniting system, then the system including fuel supply means becomes inoperative until again placed in operative condition by manual means. The invention furthermore provides that during normal operation when the fire is going should there be a failure of the flame there will automatically be an attempt to relight the fire, and if it cannot be automatically relit then the furnace will be shut down.

We thus provide not only an improved igniting means but also the necessary system whereby hazardous and explosive conditions are avoided. Such conditions would be present, and are fact many times present in past operation and systems, where fuel is continued in supply to an incandescent furnace after the flame from the burner has for some reason been extinguished.

Our invention has for one purpose a rapidly igniting means such that the time taken to initiate ignition after the fuel supply has become effective is extremely short, thus avoiding waste of fuel and the inherent danger of unburned fuel being fed to a furnace to provide explosive or hazardous conditions in the combustion chamber.

Specifically the improved igniter which we disclose herein may be used in many forms and combinations of furnaces and burners. Igniters is made to the accompanying drawings illustrating preferred embodiments of our invention.

Fig. 1 is a diagrammatic view of the ignition control system in combination with a fuel burner.

Fig. 2 is a sectional elevation of an igniter and its actuating mechanism.

Fig. 3 is a side elevation of a part of Fig. 2.

Fig. '4 is a longitudinal cross section of an igniter. s

Fig. 5 is .a perspective of another form of igniter.

Figs. 6, '7 and 8 are details of Fig. 5.

Fig. 9 illustrates a further arrangement of an igniter in a furnace.

Fig. 10 is a plan view of Fig. 9 with a portion of the top of the furnace broken away" to expose one of the two igniters employed in this form of the present invention.

Generally our invention covers the problem of starting a cold furnace and to continue the attempts at ignition until the fuel is lighted, or for a predetermined number of times. The ignition means we provide are moved into the path of the fuel leaving a burner and when ignition is accomplished is then automatically retracted.

The 'igniter of this retractible system is of such 30 After ignition is effected, other means automatically are employed to make the operation of the retractible igniter ineffective and keep it from the path of the flame until it is again needed. Should ignition fail to occur thenthe system will cycle and attempt to effect ignition a predetermined number of times and then shut off the fuel supply. By deenergizing. and retracting, re-energizing and repositioningv the igniter, any possibility of combustion occurring during the scavenging, between tries, is eliminated. Such aretractible ignition system has many additional in the past have been proposed which protrude a substantial distance into the combustion chamber in line of fuel feed from a burner or burners and remain subjected to the flame after combustion is initiated; An igniter .in such position readily becomes clogged, and thus eventually useless, this being especially true where pulverized coal is the fuel. It is therefore one object of our invention to provide a retractible igniter which is automatically removed from the path of the flame and substantially from the. combustion chamber when flame is issuing from the burner or burners.

slightly therefrom. The igniter 3 is essentially Y an electrical resistance element connected in a manner to avoid grounding of the system. We prefer to use a carborundum base material, such as Globar, normally heated to about 2800 E,

which temperature is reached under different conditions in from one to five seconds. In certain With these and other objects in view reference embodiments a single heater element is' used with a return of the circuit carried through the metallic holding casing, while in other embodiments we use two or more igniter elements connected in series. In certain arrangements and under certain conditions it may be desirable to maintain a small current flow continuously through the igniter element to heat it somewhat lated against the heat, connect the terminals 6 and 1 of the igniter element with exterior circuit terminals 8, 9.

The igniter 3 is attached through a link Ill and bell crank II to the connecting rod 12 of a piston l3 adapted to reciprocate in a cylinder M. The fluid pressure in the pipe 15 will cause the piston l3 to move downwardly, thus forcing the igniter 3 into the path of the fuel ejected from the burner I; to be later retracted by the compression pring l6 upon release of pressure in the cylinder H. The arrangement is more particulaly shown in Figs. 2 and 3 which are to larger scale and less diagrammatic. The bell crank II at one end pivots about a pin l9 fixed in an arm rigidly fastened to the lower end of cylinder M. In its downward travel the bell crank ll through pin 2|, link l0, and pin 22 causes the igniter element 3 to be forced into the fuel path and assume the position indicated by the dot-dash line. As the piston is forced downwardly it compresses the spring l6 and while the element 3 is in its effective position the spring 16 is held. compressed. Whenfiuid pressure is released from the cylinder I4 the compression spring [8 immediately retracts the element 3 to a position, as shown in' Fig. 2, substantially removed not only from the path of the fuel and flame issuing from the burner l but also from the combustion space as a whole. A certain amount of air from the burner chamber entersthe furnace past the igniter element, thus keeping the igniter element relatively cool when it occupies its retracted position. Normally such air is at around 200 F. and thus serves to maintain the electric resistance element at a temperature such that neither the element itself nor its retaining metal parts are subjected to temperatures sufficient to warp or damage them.

The housing 2 in which the igniter element 3 is positioned and moved is rigidly fixed in the furnace wall or windbox in some such manner 'as is shown in Fig. 2. It may be of some metal,

such as nickel, capable (of resisting the temperaturesand service to which it is subjected. The

. igniter element assembly 3 isloosely slidable in the housing 2, which is oppositely slotted for a the igniter guides 29 to move freely therein and allow expansion and retraction of the igniter element without cramping or binding of in the metallic conductor housing 3 and is pressed downwardly by a metallic conductor rod 24, which in turn abuts a compression spring 25 at its head.

The cylinder 3 is oppositely cut away adjacent substantially the full length of the resistance element 23 to expose the heated element 23, when in extended position, to the fuel supplied through the burner I. The upper portion of the assembly comprises several insulator parts which may be of ceramic or other heat resisting material. For example, the body 26 forms a recess for containing the compression spring 25 and furthermore insulates the conductor rod 24 from the tube casing 3. An outer metallic cylinder 21 retains the various parts and provides extensions 29 which act as guides in the slotted portions of the member 2. The assembly is provided with a terminal post 3 connected to the conductor tube 3 and with a terminal post 1 connected with the conductor rod 24. A loose sleeve 28 on the pin 22 provides a bearing for the link [0. I

We have found it desirable to confine the maximum temperature of the resistance element 23 to the central portion thereof longitudinally to prevent deterioration at the ends of the element 23 where it rests in depressions of the unit 3 and of the rod 24. A portion therefore of each end of the resistance element 23 is composed of a low resistance heat resisting material which may be of Durhi or similar composition. Another possibility is to plate the element 23 for an inch or so of its length at each end with copper or similar metallic conductor. This in effect grades the temperature from a maximum at the longitudinal center of the element 23 toward each end thereof, and while providing a sufficient length of highly heated material at the same time prolongs the life of the element 23. It will be appreciated that other means of accomplishing this object may be used than those which we disclose herein.

. The igniter of Fig. 5 is of slightly diiferent construction than that of Fig. 4. Herein we utilize two similar resistance rods 23 connected in series. A metallic outer cylinder 3 is then merely a holder for the rods. The upper portions of the two rods/ are insulated from each other and from the metallic cylinder 3, as are the terminal posts}, I. The lower ends of the resistance rods 23 rest in a conductor base 3| shown in Fig. 6. This base in turn fits into a holder 32 shown in Fig. 7, and which is of insulating material. The holder 32 in turn rests in the base of the cylinder 3 in a manner such that it may not turn or allow the resistance rods 23 to contact each other or themetallic casing 3.

In Figs. 9 and 10 we show a further arrangement and specifically in connection with a pluconsiderabe portion of its length'so as to permit rality of pulverized coal burner nozzles. The arrangement i is shown somewhat diagrammatically in elevation in Fig. 9 and in top plan in Fig. 10. It will be observed that wehav illustrated a total of eight burner nozzles la and in connection therewith two igniter elements 3' clearly shown in Fig. 10, across a horizontal tion of one of the burner nozzles.

of the centrally-positioned guiding tube 52. In this embodiment the system is so arranged that the two igniters 3 are simultaneously moved into extended position and made effective together as a safety precaution, so that one at least of the fuel supplie will be ignited.

In the particular construction illustrated in 7 Figs. 9 and 10 the housing 2 is rigidly fastened by means of a plate 53 in desiredrelation to the nozzle la. Normally the igniter housing 2 and the igniter 3 (in retracted position) are out of the path of fuel or flame issuing from the nozzle la and are located in the relatively protected burner box surrounding the nozzles a. The one end of the bell crank furthest removed from the igniter element-3 is pivoted as at 19 to a support 20 which is rigidly fastened to one of the burners la. In this arrangement the spring I6 explained.

As previously mentioned, when it is desired to" effect ignition from the burner and light the,

furnace it is first necessary to close the power switch 54a and thus provide the possibility of energization to the part illustrated. Desirably the igniter 3 is first heated and positioned in front of the burner I in the path of fuel. which -will subsequently issue from the burner.- After the igniter 3 has been moved'forward to desired position, and has been given sufiicient time-to reach ignition temperature, the fuel supply is automatically initiated to the burner I. These functions are automatically accomplished by the mechanism disclosed through the rotation of the shaft 34 in one complete cycle thereof.

is of the tension type and supported between pins 55 and 56. The pin 55 is supported, as

in front of a fuel burner, or retracting it from i said position, is included. in a control system shown diagrammatically in Fig. 1 to which reference now should be made. While the arrangement illustrates a single igniter assembly, it is quite feasible to connect a plurality of assemblies into the circuit arrangement of Fig. 1. For instance, if in connection with a burner arrangement such as-is illustrated in Figs. 9 and 10 we had two, or even more, igniters, these are connected for parallel operation and only the single cycling mechanism of Fig. 1 would be necessary. It would, however, be possible if desirable to duplicate the circuit and arrangement of Fig. 1 so that. each igniter would be entirely independent in its operation from any other igniter.

In general, in Fig. 1 we provide the necessary electric circuits and mechanism for performing certain functions in desired sequence as has been brieflymentioned heretofore. The arrangement of Fig. 1 is illustrated in the condition pertaining to a cold furnace with no flame therein and with no fuel issuing from the burner I. The electric power supply switch 54a-is shown in an open circuit position, and thus all parts of the electrical circuit and mechanism are in deenergized condition. We will now describe the sequence of operation that occurs when it is desired to effect ignition and light a fire within the furnace. It is first necessary to close the power supply switch 54a, whereupon a circuit is 9 the agencyof cam 36.

through suflicient angular travel to move the completed through the switch bar 44 to energize the synchronous motor 33. This motor is provided with the necessary gear reduction to slowly has been labeled Fuel, the cam 36 Igniter, and

revolve a shaft 34 upon which are located cams 35, 33 and 31 and a cog wheel 38. The cam 35' with it a roller actuated switch arm designated respectively 4|, 4!, and 43. The wheel 38 carries near-its periphery'a roller 39 adapted to engage As the shaft 34 begins its rotation the timer cam 31 first comes into play, closing the switch 43 and completing a holding circuit forthe motor 33 to permit the motor 33 to continue operation even though the initiation of rotation of wheel 38 has caused wheel 40 to move switch arm 44 upwardly and break circuit with the contact 44b. Were it not for the holding circuit of the motor 33 completed through the switch arm 43, the motor 33 would have stopped as soon as the switch arm 44 moved away from the contact 44b. However with control of the motor 33 now in the hands of timer cam 31 the shaft 34 will make one complete revolution before the arm 43 open circuits and stops the motor 33 (assuming that the arm 44 is still out of engagement with the contact 44b).

On the premise that the timer cam 37 is going allow the shaft 34 to make only one complete revolution, the igniter cam 36 begins to close the switch arm 42, completing circuit through a signal light 4'! through a relay 45. Thus through a substantial portion of one revolution V of the shaft 34the relay-45 is closed, completing circuit to the solenoid actuated valve 46,,which opens "the valve and allows full pneumatic or other fluid pressure to be effective upon the piston l3 for moving the igniter element 3 into an extended position below the burner Simultaneously closing of the relay 45 energizes or passes current through the electric resistance element 3 for heating the same. Thus the igniter cam 35 controls the forward positioning, and the heating, of the igniter 3 into a position below the burner preparatory for lighting fuel therefrom when .the fuel supply is available.

In order to give the igniter time to become heated to ignition temperature, and to be positioned into the proper location, the contour of the cam 35 (which controls the fuel supply) provides that the switch arm 4| controlled there .by is'not actuated until some'portion of a second or seconds after closure of the relay 45 through When, cam 35 turns switch arm 4| into closed position, thence relay '48 is energized, completing a circuit through the solenoid valve 49, which initiates a supply of fuel, such as oil, to the burner I to be ignited. During the remainder of the single revolution of shaft 34, as controlled by the timer cam 31, the igniter 3 is in its extended position in the path of the fuel, the igniter is heated to' ignition temperature; and the fuel supply is available and discharged from the burner p a If ignition occurs and flame extends from out the burner I, then the presence of this flame is efiective through a guiding tube 52 upon an electhe teeth of a wheel 40, whose function willbe energized condition so that the supply of fuel to the burner I will be continued so long as flame exists.

In the meantime the toothed wheel 40 has been moved by the roller 39 a distance of one tooth, so that normally the roller of the switch bar 44 would have dropped into the next notch, but does not do so because the energization of the relay 54 holds the switch bar 44 into engagement with the contact 44a.

In the meantime the timer cam 31 has completed one complete revolution and drops out the contact arm 43, thus deenergizing the motor 33 and stopping further revolution of the shaft 34. Inasmuch as the contact bar 44 is not now in engagement with the contact 44b, the electrical path for the motor 33 cannot be completed through that path either. The return of the igniter cam 36 to. its position as shown in Fig. 1 (upon the accomplishment of one complete revolutionof shaft 34) opens the switch 42, which deenergizes the signal light 41, deenergizes the relay 45, and closes the solenoid valve 46. Closure of this solenoid valve releases air pressure within the cylinder l4 and thereafter the spring I6 is effective in automatically retracting the igniter element 3 fromthe path of the flame. At the same time deenergization of relay 45 discontinues heating of the resistance element 3.

Normal operation then is that ignition has been effected and flame is extending below the burner I to which the electric eye 5| is respon sive in maintaining the supply of fuel to the burner. The igniter 3 has been returned to its retracted position in a cooler location. The entire system and mechanism is in condition for functioning to attempt to effect reignition should the flame for any reason be extinguished.

We will now describe two further sequences of operation, namely, what would have happened had the flame failed to ignite; and what will happen if the ignited flame fails.

If for some reason upon the completion of one revolution of the shaft 34 there is no flame below the burner I to which the electric eye 5| may be responsive, either from a failure of fuel to be supplied through the open solenoid valve 49, or through some failure of the fuel to be ignited, then in general the system will cycle a predetermined number of times to attempt to ignite the flame. If at the end of these successive attempts the flame is still non-existent the system will shut down and can only be started by manual means.

Following the previous explanation of the functioning of the various parts, it will be assumed that the igniter element 3 is in proper position below the burner and is at an igniting temperature. The fuel valve 49 is open, but for some reason no flame exists below the burner. Thus there 5 no energization of the electric eye 5| and no energization of the relay 53. Thus the relay 54 is not holding the switcharm 44 against the contact 44a, but the switch arm 44 is laying by gravity against the contact 44b, its

roller having dropped into the next notch of the wheel 40. As the timer cam completes its revolution and the entire cam system assumes the position shown in Fig. 1, the igniter automatically retracts and is deenergized and the fuel valve 49 is closed. The electric supply switch 54a being closed, the complete cycle is then repeated in an attempt to light the flame. This continues as many times as there are teeth on the wheel 40, and obviously this may be arranged for three cycles, five cycles, or as desired.

Assuming that even after the predetermined number of tries the igniter has been unable to light the fuel issuing from the burner I, then the raised portion 40a of the wheel 40 (in counterclockwise rotation) has been placed beneath the roller of the switch member 44, which results in said switch member being held intermediate thecontacts 441: and 44b in a position so that neither of the contacts closes circuit with the power source. In the meantime the timer cam 31 opens the switch 43 and the motor 33 is deenergized without being ableto restart through the circuit of contact 441). The result is that the igniter is retracted, it is deenergized and cooled, and

the fuel supply valve 49 is closed, until such time as an operator manually resets the cam train to a position wherein the roller of the switch bar 44 is off from the land 40a and proper cycling may be had. Obviously this manual resetting of the mechanism would not be made until investigation was had as to the reason for failure to ignite on the predetermined number of cycles.

The next condition to be described is one wherein normal ignition has been effected and after some period of time the flame for some reason fails. Stopping of the light which is effective upon the electric eye 5| deenergizes the relay 53 and closes the fuel supply valve 49. Immediately thereafter the mechanism cycles to attempt to reignite the flame and, if after the predetermined number of attempts, it is impossible to ignite the flame, then the system (as has just been described) shuts down the fuel supply and becomes ineffective until manually reset.

While we have illustrated and described certain preferred embodiments of our invention, it is to be understood that we are not to be limited thereto but only as to the claims in view of prior art.

What we claim as new, and desire to secure by Letters Patent of the,United States, is:

1. In a control system for fuel burners, in combination, a burner for discharging fuel to be burned in suspension, an igniter for the fuel, cyclic means for energizing the igniter and positioning it in the path of the fuel, said cyclic means then initiating a flow of fuel to said burner, and next deenergizing and retracting the igniter from the path of the fuel; and flame sensitive apparatus which operates upon initiation of flame by the igniter to render the cyclic means ineffective after" the igniter has been retracted but if ignition is not initiated and flame is not present at the burner to permit said cyclic means to repeat thelighting cycle a predetermined number oftimes.

2. In a control system'for fuel burners, in combination, a burner for discharging fuel to be burned in suspension; an igniter m the fuel; means for energizing and deenergizing said igniter; a fluid pressure power means" for positioning the igniter in'the path of the fuel and for retracting it therefrom; a solenoid valve contract the igniter from the path of the fuel; and 10 flame-sensitive apparatus which operates upon initiation of flame by the-igniter to render the cyclic means ineffective after the igniter has been retracted but if ignition is not initiated and 'fiame is not present at the burner to permit said cyclic means to repeat the lighting cycle a predetermined number of times.

ERV'IN G. BAILEY. PAUL S. DICKEY.

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