US3476492A - Electrical ignition system - Google Patents

Description

ELECTRICAL IGNITION SYSTEM Filed Nov. 13, 1967 2 Sheets-Sheet 1 44 4 Lazy? 7 (61 r 7 9 1,? J0 J0 United States Patent Ofi ice 3,476,492 Patented Nov. 4, 1969 3,476,492 ELECTRICAL IGNITION SYSTEM Harold G. Roberts, Medinah, Ill., assignor to Chicago Dryer Company, Chicago, Ill., a corporation of Illinois Filed Nov. 13, 1967, Ser. No. 682,116 Int. Cl. F2311 /20 US. Cl. 431-71 2 Claims ABSTRACT OF THE DISCLOSURE A spark is discharged adjacent the first burner tip of a gas burner tube disposed in the main ironing cylinder of a gas-heated ironer or the like. Simultaneously, a combustible gas-air mixture is passed into the tube and the mixture is ignited at one end of the tube having a plurality of spaced burner tips disposed along the length thereof. A time delay relay is also energized simultaneously. A flame rod disposed over the terminal burner tip completes a circuit as flame surges from such tip, thereby stopping the sparking and placing the system in automatic operation. If flame does not reach the flame rod within the time set by the relay, the fuel input into the burner is terminated by the relay, and a safety switch terminates the sparking action shortly thereafter.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to improvements in controls for gas-fired burners such as are employed in commercial ironers and the like.

Prior Art The prior art although cognizant of the necessity of safety controls for burners of combustible mixtures as in US. Patent Nos. 2,503,260 and 2,563,230, fails to provide the flexibility of control and complete protection which present day commercial machinery demands for safety and convenience of operation. The prior art devices of the type hereinafter disclosed generally comprise a fixed arrangement of components which cannot be altered, or altered only with difficulty, to meet varying conditions of operation. In addition, normally a single safety device adapted to interrupt the supply of nonignited fuel is employed rendering safety of operation dependent upon the proper functioning of a single element.

SUMMARY OF THE INVENTION It is an object of this invention to provide a control for a gas burner such as may be incorporated in a commercial ironer or the like in which the passage of a combustible gaseous mixture into a burner is automatically and precisely controlled whereby the possibility of dangerous accumulation thereof without ignition is eliminated by the action of a plurality of safety circuits, which avoid dangerous gas accumulation and ignition of that gas which has accumulated.

It is another object of the provided control to provide a flexibility of operation whereby the control may be readily set to provide optimum safety in burners of varying design and capacity.

It is yet another object of this invention to provide a burner control composed of a minimum number of readily available parts which provide automatic ignition and continuous operation in complete safety without the necessity of constant surveillance.

In one illustrative embodiment indicating the manner in which the provided invention functions, a heated roll of an ironer employs a burner tube extending along the length of the interior thereof with a plurality of burner tips arranged at intervals along the length of the tube. A control comprising this invention, including a sparking electrode spaced from a ground strip disposed adjacent the first burner tip, is adapted to ignite the gaseous fuel of the burner in complete safety.

Subsequent to the closing of a starter switch, an ignition transformer is energized to form a spark between the electrode and ground strip. A fuel valve is opened, passing a combustible air-gas mixture into the burner tube. The spark ignites the gas emerging from the first burner tip, and flame passes from tip to tip until the gas emerging from the terminal tip is ignited.

Also energized simultaneously is a time delay relay which is adapted to close the fuel control valve unless the gas emerging from the burner terminal tip is ignited within a pre-set time interval.

A flame rod disposed above the terminal burner tip electrically communicates with the time delay relay upon impingement thereagainst of flame heat. If all of the burner tips are ignited within the safe time interval prescribed by the relay, the sparking is terminated and the fuel control valve allowed to remain open. Subsequent operation is then controlled by a thermostat.

If for any reason flame from the terminal burner tip does not engage the flame rod within the time dictated by the relay, the fuel valve will close and shortly thereafter a seperate safety switch will warp out breaking the circuit energizing the electrode transformer. The latter safety switch will operate soon after the time delay relay and thus comprise a second safety device preventing ignition after the gas feed has terminated.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a gas heated flatwork ironer adapted to utilize the safety control of this invention;

FIG. 2 is a view similar to FIG. 1 depicting the opposite side of the ironer illustrated in FIG. 1;

FIG. 3 is a fragmentary sectional view partly broken away of the heated ironing roll utilized in the ironer of FIGS. 1 and 2; I

FIG. 4 is a left end view of the roll of FIG. 3;

FIG. 5 is a right end view of the roll of FIG. 3; and

FIG. 6 is a schematic wiring diagram relating to the safety control utilized in conjunction with the ironer of FIGS. 1 and 2.

Referring now more particularly to FIGS. 1 and 2, a gas heated flatwork ironer 10 is illustrated which is sold by the Chicago Dryer Company of Chicago, 111., and identified by Model No. GA16. The sheets or other linens to be ironed are placed on feed ribbons 12 schematically illustrated, which carry the items under a finger roll 14, see FIG. 2, and two padded compression rolls 16 which, being driven at a higher speed of rotation than main ironing roll 18, tend to smooth the item being ironed, eliminating all wrinkles as the sheet is driven between the padded rolls 16 and the larger heated ironing roll 18. The ironed item may be discharged onto a table 20 disclosed at the feed end of the machine or it may be discharged by means of a lower conveyor 22 onto a receiving platform 24 disposed at the rear of the machine.

FIG. 1 illustrates basic elements utilized in the Chicago .Dryer Ironer Model GA16, including a main drive motor 26 which drives a main drive gear 28 through an intermediate gear box 30. The drive gear meshes with large gear 32 connected to the main heated ironer roll 18. Gear 32 rotatably drives in opposite directions of rotation, gears 34 connected to the padded compression rolls 16 whereby the main ironer roll 18 rotates in a direction opposite that of rolls 16, also gears 32 and 34 may be driven by a chain also engaging drive gear 28.

FIG. 2 illustrates a blower motor 36 which forces a predetermined mixture of gas and air into a burner tube 38 more clearly seen in FIG. 3 Also illustrated in FIG. 2 is an overlying exhaust hood 40 which, in conjunction with a blower motor 42 and ductwork 44, is adapted to exhaust products of combustion which are produced by the burner tube 38 from the vicinity of the ironer. The heated ironer roll 18 is open at opposed ends as is more clearly seen from FIGS. 4 and 5 and therefore the products of combustion resulting from the burning of gases forced into burner tube 38 are not retained within the roll 18. Accordingly in the normal course of ironer operation both blower motor 36 which feeds the fuel into the burner tube 38 and blower motor 42 which exhausts the products of combustion from the vicinity of the ironer must be operating.

It has been common practice, utilizing gas heated ironers such as that depicted in FIGS. 1 and 2 of the drawing, to employ a constantly burning pilot light for purposes of igniting the fuel which is forced into the burner tube 38 as by means of the illustrated blower motor 36. However, this practice has proved unsatisfactory from a safety standpoint inasmuch as on occasion one or more of the discharge openings or burner tips, such as openings 46 illustrated in FIG. 3, become clogged, resulting in an accumulation of non-ignited gas in a specific location within the roll 18.

Assuming that a constantly lit pilot light was disposed adjacent the left hand end of the burner tube 38 of FIG. 3, in the event that one or more of the discharge openings 46 were clogged, preventing a uniform jumping of the flame from left to right as the gas is discharged from the unclogged openings 46, a rather large volume of gas may accumulate in the right hand end of the roll before contact is made with such flame, resulting in an explosion. Inasmuch as some of the rolls 18 may be 8 feet in length, or greater, the hazard inherent in the use of a constantly burning pilot light for igniting the gas emerging uncontrolled from the burner tips 46 such as those illustrated on tube 38 is apparent.

In accordance with this invention, an electrical ignition system has been provided which assures the safe ignition of the gas which is being fed into the burner tube of an ironer roll within a desired time limit such as five seconds or the like. If ignition has not commenced at the end of such prescribed safety period, the supply of fuel gas into the burner tube is automatically cut off preventing any dangerous accumulation of gas which could lead to an explosion in the manner above described. An additional safety element will de-energize the igniting means shortly after the supplying of gas has terminated.

In FIG. 3 there is illustrated an electrode 50 maintained at a desired interval from a ground strip 52. The latter strip extends over the initial discharge tip 46i of the burner tube 38 in the manner more clearly seen in FIG. 4, comprising a left end view of the apparatus illus trated in FIG. 3. In the normal course of operation, a high voltage spark will be discharged between the tip of the electrode 50 and the ground strip 52 at the same instant that gas and air are being forced into the burner tube 38 by means of the blower motor 36. Assuming that there is no obstruction in any of the burner tips 46, the spark created between the electrodes 50 and 52 will ignite the gas emerging from burner tip 461 and flame will jump from left to right until gas emerging from a terminal tip 46: is ignited. A heat sensitive element or flame detector 48, see FIG. 5, is disposed over discharge tip 46t, and upon having a flame impinge thereagainst, will send a signal to a relay terminating sparking between the electrode 50 and strip 52.

Simultaneously with the initiation of the sparking over the burner tip 46i, a time delay relay is energized which is set for a predetermined period of time within which the flame must reach the flame detector 48. If the flame does not reach the detector within the prescribed period of time, a solenoid of a fuel valve such as valve 54 illustrated in FIG. 2 is de-energized to close the valve and immediately terminate the feeding of fuel into the burner tube 38. The fuel which has passed into the burner tube during this interval is inadequate to create a damaging explosion. A safety switch will subsequently terminate sparking shortly after closing of the valve 54, and the attendant in the vicinity of the ironer will than have an opportunity to immediately examine the burner tube in complete safety for purposes of determining the cause of the failure of the flame to reach the flame detector 48 within the time period dictated by the time delay relay.

For a fuller understanding of this invention reference will now be made to the schematic wiring diagram of FIG. 6 which is illustrative of circuitry which maybe employed in effecting the desired control of the electrical ignition system of this invention. The following steps are carried out in utilizing the ignition system of this invention. A starter button 60 conveniently disposed on the ironer frame is pushed closing the contacts of relay 61 and starting blower motor 36, the hood or canopy motor 42 and the main drive motor 26. Safety switch or finger guard 63 must be in the closed condition to enable the ironer to operate and is opened when an attendant feed ing items into the ironer inadvertently allows her fingers to approach the heated roll 18 thereby tripping a safety bar which opens switch 63.

Disposed in the conduit 55 suppling the air to the burner tube 38 is a fuel pressure switch 64; disposed in the ductwork in which the gases of combustion are exhausted by the canopy motor 42 is a canopy pressure switch 66. These two switches are closed only when there is a gaseous flow, thereby assuring proper functioning of the blower motor 36 which feeds the fuel into the ironing roll 18 and the exhaust motor 42 assuring efficient discharge of the gases of combustion from the hood 48 to the exterior of the building in which the ironer is disposed.

Simultaneously with the starting of three motors, power is applied to transformer 68 comprising a component in a protection relay 70 which is commercially available under Model No. RA 890E from the Honeywell Company of Minneapolis, Minn. The energized transformer 68 causes a vacuum tube in electronic net-work 72 of the relay 70 to heat up energizing a flame relay 74 comprising coil 1 and normally closed contacts F1 and F2 and normally open contacts F3 and F4 controlled thereby. The flame relay closes a check relay comprising coil C and normally open contacts C1. When the check relay is energized a signal is applied to the electronic network 72 which de-energizes the flame relay. A check current may then pass through the normally closed contacts F1, and assure the closed condition of the above mentioned switches 64 and 66 in addition to the closed condition of gas control switch 73 which assures that the gas feed line is open, thermostat 76 and temperature limit switch 78, all five of said switches being in series as depicted.

If all five switches are closed, then the relay 84, comprising coil L and normally open contacts L1 and L2, is energized allowing current to energize the solenoid of gas valve 54, thereby opening the same. Current is allowed to pass to the valve 54 through the closed contacts L1 of relay 84, closed contacts of time delay relay 86 and the closed contacts K1 of relay 96. Thus, simultaneously with the opening of the gas valve 54, time delay relay 86 is energized making it necessary for the flame to reach flame detector 48 within the time period prescribed by the relay 86 or the closed contacts thereof will be opened, breaking the circuit to valve 54, closing the same.

Current also passes to the ignition transformer 90 through contacts L1 and F2 thereby initiating sparking between electrode 58 and strip 52 as the gas valve 54 is opened and the time delay relay 86 is energized. The time delay relay is commercially available under Model No. 10337H192-E and is sold by the Cutler Hammer Company of Milwaukee, Wis.

Assuming that the flame, initiated by the spark gap between electrode 50 and strip 52 progresses along the length of the burner tube 38 so as to reach the burner tip 46t and engage flame detector 48 within the time period necessary to open the contacts of the time delay relay 86, a signal is sent by the flame detector 48 to the electronic network 72 again energizing the flame relay 74. With this energization, relay 84 drops out and the current to the ignition transformer 90 which had previously passed through normally closed contacts F3 is terminated stopping sparking between the electrode 50 and ground strip 52.

As contacts F2 are opened, contacts F3 are closed and current passage through contacts K1 of relay 96 permits energization of coil K of relay 96 which is commercially available under Model No. 488G from the Honeywell Company of Minneapolis, Minn. The latter relay permits continued energization of the coil of the solenoid in the gas valve 54 by current flow through contacts K2 inasmuch as the time delay relay 86 has now dropped out as a result of contacts L1 opening upon energization of the flame relay 74 and the subsequent de-energization of the coil L of relay 84. When relay 84 becomes de-energized, energization of relay 96 through contacts L1 is prevented, but energization of the latter relay is accomplished through contacts F4.

The gas valve 54 will remain open and combustion will continue until the temperature within the ironer roll 18 attains the maximum temperature allowed by thermostat 76. When this occurs, the switch of thermostat 76 will open and the gas valve 54 will close and remain closed until the lower temperature for which the thermostat is set is reached and switch 76 again closes. Inasmuch as the five switches 64, 66, 74, 76 and 78 will once more be closed in series, a repetition of the sparking operation will take place resulting in reignition, assuming the same occurs within the time period prescribed by the time delay relay 86 in the manner above described. The temperature limit switch 78 comprises an auxiliary safety device disposed adjacent the surface of ironing roll 18 which assures closing of the gas valve in the event of any malfunction of the thermostat 76 which is adapted to ride on the ironer roll surface. Such malfunction may prevent breaking of the circuit by the thermostat while maintaining the gas valve 54 in the open position at an elevated temperature.

In the event that the flame detector 48 does not transmit a signal to the electronic network 72 within the time limit dictated by the time delay relay 86, the time delay relay contacts will open breaking the circuit energizing the solenoid which maintains the gas valve 54 in the open position. Inasmuch as the flame relay 74 will not then become energized as a result of any signal emitted by the flame detector 48, the operation of the ignition transformer 90 will then be terminated by heating element 95 which will continuously heat safety switch 97 until the latter switch comprising a bimetallic element warps, breaking the circuit through the switches in series, and de-energizing the relay 84 and thereby closing contacts L1 and terminating energization of the ignition transformer. The contacts of switch 97 must be manually closed after element 95 and switch have cooled.

It is seen therefore that a novel system has been provided for igniting a gas heated ironer in complete safety without any danger of a fuel accumulation which could perhaps result in an explosion which could be damaging. The provided system allows flexibility in operation, inasmuch as a specific time delay relay 86 may be inserted into the system to provide the desired safety time for the specific burner which is being ignited. As is apparent from the foregoing description, the provided system not only assures ready shut-down or closing of the fuel valve but in addition assures cessation of the sparking transformer Within a short, safe time period. Although the foregoing description has been specific with respect to a gas heated ironer, it is obvious that the provided ignition system will function to advantage in any system employing fuel in a manner similar to that above described.

While particular embodiments of this invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. Therefore, it is contemplated by the appended claims to cover any such modifications as incorporate those features which may be said to constitute the essential features of these improvements, within the true spirit and scope of the invention.

I claim:

1. In a gas burner control assembly, an elongate burner having a plurality of burner tips spaced along the length of-said burner, means for supplying a combustible gaseous mixture along the length of said burner for discharge through said tips, electrical ignition means for igniting the gaseous mixture discharging from the burner tip disposed adjacent one end of said burner, valve means for controlling the passage of gaseous mixture to said burner, adjustable timer means connected to said valve means and adapted to close said valve means after the expiration of a preselected period of time; heat sensitive means disposed adjacent a burner tip at a second end of said burner opposite to said one end and adapted to de-energize said timer means upon sensing heat at said second end whereby said valve means will remain open after the expiration of said preselected period of time; means for exhausting products of combustion from the vicinity of said elongate burner, and means responsive to both a desired pressure in said means for supplying a gaseous mixture and to proper operation of the exhausting means for substantially simultaneously opening said valve means, energizing said ignition means and energizing said timer means.

2. The assembly of claim 1 in combination with thermostat means sensitive to the heat generated by said burner; said valve means being responsive to the condition of said thermostat means whereby said valve means is closed when a predetermined temperature is sensed by said thermostat means.

References Cited UNITED STATES PATENTS 2,302,456 11/ 1942 McCollum 43171 X 2,335,471 ll/1943 Ashcraft 431- X 2,399,673 5/1946 Hall 43166 X 2,503,260 4/1950 Hall 431-74 3,056,398 10/ 1962 Kirk 431-31 X 3,064,719 11/ 1962 Graves 43 l26 3,162,429 12/ 1964 La Pointe 43 l46 X 3,343,585 9/1967 Eckelberry 43 131 3,393,037 7/ 1968 Giuifrida et al 431-31 X EDWARD G. FAVORS, Primary Examiner

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