US1807302A

US1807302A - Control system for burners

Info

Publication number: US1807302A
Application number: US179429A
Authority: US
Inventors: Marshall H Braden
Original assignee: NU WAY CORP
Current assignee: NU WAY CORP
Priority date: 1927-03-30
Filing date: 1927-03-30
Publication date: 1931-05-26
Anticipated expiration: 1948-05-26

Description

May 26, 1931. M. H. BRADEN CONTROL SYSTEM FOR BURNERS Filed March so, 1927 4 Sheets-Sheet l Winess $3 2*! M31 y 26, 1931- 4 M. H. BRADEN 1,807,302

COHTROL SYSTEM FOR BURNERS Filed March 30, 1927 4 Sheets-Sheet 2 May 26, 1931;

M. H. BRADEN CONTROL SYSTEM FOR BURNERS Filed March 50, 1927 4 Sheets-Sheet 3 May 26, 1931. M. H. BRADEN CONTROL SYSTEM FOR BURNERS Filed March 30, 1927 4 Sheets-Sheet 4 Patented May 26, 1931 UNITED STA' IZES" PATENT OFFICE MARSHALL H. BRADEN, OF ROCK ISLAND, ILLINOIS, ASSIGNOR TO THE NIT-WAY COR- PORATION, OF BOOK ISLAND, ILLINOIS, A CORPORATION W018 CONTROL SYSTEM ron BURNERS Application filed. March 30,

The present invention relates to control systems for burners, having particular reference to electrically operated control systems 7 designed for automatically controlling the operation of an oil or gas burner, the exercise of this automatic control being generally in. accordance with the difierent temperature requirements imposed upon the furnace-or upon whatever device is being heated by the 10 burner. The invention has its principal field of utilityin conjunction with oil or gas burners of the class employed for firing domestic heating plants used in homes, buildings, etc., and accordingly in the following description I shall refer to such embodiment of the invention, but it will be understood of course that the broad features of the invention can be employed in conjunction with any type of burner heatedfurnace or like device where automatic regulation is desired. One of the principal objects of the inven- 7 tion is to simplify the circuit connections in these control systems, to the end of reducing the initial and maintenance costs of the burner installation, as well as to assure greater reliability of operation. Heretofore, all of these automatic control systems with which, I am familiar have each involved a complicated network of circuits which are a considerable source of expense and trouble, both in installation and in the maintenance of the burner. In this regard, it is a further ob ject of the invention to provide a control sys t'em wherein there are practically no unguarded intervals i; e. abnormal conditions when the proper cyclical operation of the w v urner might be interrupted "or dangerous conditions allowed to develop.

Another'object ofthe invention is to pro-' .vide a burner control system wherein the entire system is capable of operating on the same voltage. That is to say, the various a control circuits of the system are all capable of operating directly from the line voltage or 0 -from the same voltage that operatesthe elec- 'tric motor of the burner unit. Another object of the invention is to provide an improved ignition control cooperating wlth auxiliary motor means, preferably in the form of a motor operated fuel valve.

1927. Serial No. 179,429.

Another object is to provide an improved construction of circuit-breaker or safety switch and cooperating electrical connections, for opening the main supply circuit should ignition fail or combustion cease.

- Other objects of the invention pertaining todifierent structural features of the apparatus will appear at length in the following description of the invention. In the drawings accompanying this description:

Figure l is a view, mainly diagrammatic, showing the general plan and arrangement of my improved control adapted to an oil burner, including the circuit connections by which the current from a central source is supplied to the apparatus and utilized in its control.

Fig. 2 is a side view, partly in elevation and partly in section, showing the relation between the motor driven fuel shut-0E valve and the control box in which are housed the ignition and the safety cut-oil switches.

Fig. 3 is a vertical sectional view through .the fuel shut-off valve, taken on the plane of the line 3-3 of Fig. 2.

Fig, 4 is a front elevational view of the interior of the control box, showing the ignition.

and safety switches therein.

Fig. 5 is a vertical sectional view through the thermostatic element of the safety switch. ig. 6 is a horizontal sectional view through the c 1 1ntrol box taken just above the ignition switc Fig. 7 is an enlarged detail section taken v on the plane of the line 7-7 of Fi 6.

Fi 8 is a simplified circuit d iagram of the a ove control system, and

Fig. 9 is a view, mainly diagrammatic, slgowing' the general plan and arrangement 0 to gas burning apparatus.

In Figure 1 I have illustrated the present control system as being cising its control functions on anoil burner of the general construction disclosed. in my copentling application, Serial No. 14,151, filed March 9, 1925. It will be understood, however,that this particular burner unit has been chosen merely for illustrating a typical adaptation of the present control system, and

my improved control system when adapted arranged for exer- I 30 into the combustion chamber.

performed by 4 nating gas through the operation of suitable mounted the motor driven burner unit 13 This burner unit comabove referred to. prises an electric motor 14, a fan or blower 15 J and an atomizing fuel pump 16, all axially alined and connected together to form a uni- 15 tary assembly which is mounted on a base 17 supported in front of the furnace. The im-' peller of the blower and the rotor of theretary atomizing pump are both the armature shaft of the motor, or on shafts.

coupled directly to this armature shaft, so

that both of these elements rotate directly with the motor armature. The outlet of the blower discharges through a conduit 18 entering'the combustion chamber of the furnace through the front thereof. The fuel is con-' ducted from the outlet port of the atomizing pump through a discharge pipe 19, which enters the conduit 18 and extends forwardly therein to. a nozzle designed to spray the fuel In the particular construction of atomizing pump shown in my copending. application, provision is'made for admitting air to this pump for mixing with the fuel in the pumping 3 operation, such atomized mixture of fuel and air being discharged through the pipe 19 to the combustion chamber.

The step of i gutin g the fuel is preferably st igniting a jet of illumi? electrical ignition apparatus, and then employing this gas flame to ignite the discharged mixture of fuel and air. The gas supply means consists of a pipe 21 which enters the air conduit 18 and extends forwardly therein.

to a suitable gas nozzle disposed to project its gas flame in proximity to thejet of fuel issuing from the fuel discharge pipe 19. This gas supply is controlled by a shut-ofi valve 22 .5 interposed in the pipe line 21, such shut-off valve being electrically operated through the instrumentality of a solenoid 23 or other B1861 tricallyactuated means. The spark ignition is obtained from a vibrator coil, or transformer, indicated at 24, the secondary winding thereof having one side grounded at 25 and having its other side connected through wire 26 leading out throu h the air conduit 18 to a sparking electrode 2 disposed in position to. ignite the gas dischargedfrom the gas pipe 21.

' The main thermostat to which the entire burner system must respond in meeting the heat requirements imposed upon the furnace h is indicated at 28. the case-of a domestic mounted onheating plant thisthermostat is usually located 1n the living quarters of the dwelling and is generally referred to as the room or house thermostat. .It preferably comprises a mercury tube switch consisting of a glass tube 29 in one end of which are embedded two

contact terminals

31 and 32. The tube contains a globule of mercury and when such tube is tilted in onedirection, this mercury completes the circuit through the

terminals

31 and 32, and when the tube is tilted in the other direction, the mercury flows away from such terminals and thus opens the circuit. This tube is supported in clips on a rotatable member 33, which is connected to a bi-metallic strip or any other suitable thermally respon-f sive element, capable of giving the desired tipping movement to the tube.

Another of such mercury tube switches is indicated at'35 in Fi ure 1. This switch is responsive to'the combustion of the fuel and exercises a supervisory or safety control over the entire system so that .there is "no 'pos-' sibility of the burner continuing to project liquid fuel into the furnace if ignition'should fail or combustion cease. This switch, often referred to as the stack control, preferably has the same arrangement of two contacts 36 and37 embedded in one end of a glass tube containing a globule of mercury. The tube is arranged -to be tipped into circuit opening or closing position through a thermostatic element, such as a twisted bi-metallic ribbon 38. This thermostatic element isarranged to project into the stack or into the furnace at any preferred point where it will respond quickly to combustion temperatures. The

arrangement is such that when the thermo-.

static element 38 is cold, the tube 35 will be tipped to its open circuit position, and that as the thermostatic element responds to the temperatures of combustion in the furnace, the tube will be tipped to its closed circuit position.

- Referring tion thatexists between this fuel control and the control of the ignition system, itwill be observed from Figure 1 that the fuel supply pipe 4:1, communicating with the atomizing pump 16, has connection with a constant level float chamber Any suitable fuel regulating valve 43may be interposed inthe pipe 41 for proportioning the richness of the fuel mixture. The chamber 42' contains any suitable float controlled valve mechanism whereby a substantially constant level of fuel is maintained in such chamber; Com

is a straining chamber 44 housing any suitable straining screen. These two chambers are preferably carried-by or form a part of the base 17. The fuel supply pipe which conducts'the fuel from the supply tank .to th straining chamber is indicated at 45.. Internow to the control of the fuelsupply to the burner unit 13, and to the relabined with the lower portion of this chamber front of such shut-off valve is a control gear housing 52.

vos

tends into the gear housing and carries a pinbox 47 in which are housed the i nition and safety switches, this control box being preferably associated directlywith the motor operated shut-off valve inasmuch'as the electric motor of the latter is arranged to serve as a control unit both for. the operation 'of the. movable valve element and for the-operation fr of the ignition switch. The shut-off valve and-control box are preferably disposed in immediate proximity to the burner unit, such location facilitating the making of the pipe connections between the source of fuel supply and the barrier, but it will be obvious that the shut ofi valveand control box might have suitable mounting on the floor, ceiling, or Wall at any other point, if desired.

' Referring now to the detailsof construction of the shut-off valve, as shown in Figs. 2 and 3, such valve comprises an electric mofor 48 and a lower valve housing 49. Formed integral with the frame casting. of the motor is a lower boss portion 51 and'an upper gear housing portion 52. A front cover plate 53 is remov'ably secured to the motor housing, such cover plate having component parts completing the lower boss 51 and the upper Extending vertically through the s and gear housing is a reciprocable rod or stem 54 which supports the valve head 55 at its lower end and which extends out at its upper end through an opening in the top of the gear housing. This rod is guided in

suitable bearing bosses

56 and 57 carried on the inner side of the removable cover 53. One side of the rod 54 has rack teeth 58 formed therein through which -a drive is transmitted from the armature shaft of the motor 48 to such rod, this drive occurring through speed reduction gearing illustrated in Fig. 3. The armature shaft 59 ex ion 61 which meshes with a large gear 62-suitably journaled in the housing. This large gear carries .a pinion 63 which meshes with a second large gear 64 which is also suitably j ournaled in the housing and which carries a pinion 6 5. The-latter pinion meshes with athird large gear 66 also journaled within the housing and carrying a pinion 67 which meshes with the rack 58. The arrangement 55' is such'that the driving rotation of the armature shaft will transmit a slow speed drive through the aforementioned gearing to the pinion 67, and will rotate the latter in a direction'to drive the rack'upwardly, thereby raising the valve 55 from its seat 68.

V The inlet passageway 69 of the shut-01f valve opens into a chamber 71 above the valve seat 68, and the outlet passageway 72 opens downwardly from below the valve seat, so

7 that whatever pressure is efiective on the fuel will always assist in holding the .valve to its seat. Disposed within the chamber 71 around the valve stem or rod 54 is a sylphon bellows 73. The lower end of the l hon is soldered or otherwise secured by a uid-tight joint to-the head of the valve 55, and the upper end of this sylphon has an outwardl extending flange 74 which is clamped in a uidtight joint between theto ing 49 and the bottom of the boss 51. The

the bellows with the movement of the valve will maintain'a hermetic seal between the oil passageways of the valve casing and the exterior of the casing, thereby preventing any possibility of leakage of the oil. A heavy compression spring 75 extends down into the sylphon, bearing at its lower end on the head of the valve or on a suitable abutment carried thereby, and bearing at its' upper end against the underside of the guide boss 57, this spring normally tending to hold the valve down against its seat 68. A sleeve 76 surrounds the stem 54, inside of the spring 75, the lower end of such sleeve bearing on the head of the valve and the upper end thereof terminating a predetermined distance boss 57. underside of such boss in the upward movement of the valve so as to serveas a stop for limiting the movement of the valve in this direction.

The motor 48 is of a type which can be cc expansiveand contractive movement of I below the guide The sleeve is adapted to strike the' of the valve housheld at a dead stall indefinitely on its circuit the sleeve 76 abuts the underside of the boss 57. When this occurs the motor comes to a dead stall, the sustained torque of-the arma:

ture shaft holding the valve in raised position and permitting a continuous flow of fuel to the burner. When such motor is cut off the line at the end of the burner operating cycle, the spring 7 5 forces the valve 55 down to its seat, the free rotation of the armature in the opposite direction permitting this downward movement of the rack s Fastened to the p'rojectingupper end of the rod 54 by a screw 78 is an arm 79 which extends forwardly over the top of the. switch box 47. A long screw or bolt 7 81 threads through a tapped hole in this arm and passes down through an opening 82 in the top of the box, such bolt or screw having a suitable lock nut 83 for maintaining any desiredvertical adjustment of the screw in the arm'79. The

lower end of this screw is adapted to engage tube in one end ofcwhich are

embeddedtwo contacts

86 and 87 These contacts are 'connected through flexible conductors 108 and to the un erside of the rocking plate 84, and

108 with

connector terminals

109 and 110 mounted on an insulating panel 95, thelatter being suitably supported on the rear wall of the-switch box.- As will be hereinafter described, the ignition circuit has connection with these

terminals

109 and 110. The

' mercury t be is supported in clips 88 fastened such plate has a rearwardly extending arm 89 (Figs. 2 and 6) which is bent downwardly at its end to have bearing support on a pin 91 extending between two spaced

bearing plates

92 and 93. Referring to Fig. 7, these two-plates are spaced by posts 80, and one edge of the rearwardly extending arm 89 is preferably provided with projecting lugs 90 adapted to engage one of these posts tolimit the rocking movement of the switch in each direction. The bearing plates'92 and 93 are suitably supported by spacing posts 94 on the back panel 95. A' weight 96 is secured to. the rocker 84 adjacent the left hand end thereof, such weight thereby tending to rock the ignition switch downwardly to the left to position of the fuel valve 55, .the ignition switch will be tipped downwardly to the right to its circuit closing position, in opposition tothe action of the weight 96 and spring 97. When the motor driven shut-off valve is operated to open the valve this screw 81 moves upwardly with the upward movement of the valve, thereby permitting the ignition switch to, tip downwardly to'the left, to the circuit;

opening position illustrated in dotted lines. The left hand end of the rocker plate 84 has a slot'98 therein through which extends a .rod

' the piston head. It w'illhe' seen from the foregoing that when the motor operated fuel 99- having connection at its lower end with a suitable. motion retarding device, such as the dash-pot 101. This dash-pot comprises a cylinder 102 suitably secured to the back wall of the'control-box, the upper and lower ends of which cylinder are closed by end-heads103 and 104 for confining a body of oil or other damping liquid therein. The rod 99 extends down through the upper end head 104 and has its threaded lower end screwing into the head of a-piston 105. The rod isextended 4 down belowthe piston to'support a valve disk 106'which controls the by-pass poi-ts 107 in valve is actuated, and the screw 81 is caused to niove upwardly, as before described, the

tipping ofjthe ignition switch downwardly to the left under the'action of the weight 96 and s'prinlgl 97 will be retarded by the action of the'das -pot 101. This retarding action is so timed that the ignition switch will not tip to its circuit opening position 'until the ignition apparatus has had ample time to ignite the fuel. The circuit connections through which this timed i itionoperation occurs will be hereinafter escribed in connection with the description of the entire control system. 7

Also mounted in the, control box 47 is a safety or cut-out switch 111, which is arranged to cooperate with the combustion responsive switch 35 to cut off the entire burner apparatus at any time in its operating'interval should ignition fail or combustion cease.

- As previously remarked, the urpose of this the combustion chamber with fuel. The safety control is .to prevent continued operation of the blower and fuel pump in the absence of combustion, which, if not interrupted atsuch time would result in the flooding of the combustion chamber with fuel. The safety cut-out switch 111 is also preferably in the form of a mercury tube switch comprising a glass tube in one end of which are em bedded twoterminals. 112 and 113 with which the contained globule of mercury is adapted to make or break-contact. The tube is supported in'clips 114 secured to a rocking plate.

115 which has a rearwardly and downwardly extendin arm 116 also supported on-a pivot pin 11 between spaced bearing

plates

118 and 119, substantially similarly to the pivotalmounting of the upper rocker plate 84. A weight 121 secured to the left hand end of the rocker plate normally tends to tip the cut-out switch downwardly to the left for opening the circuit through the

terminals

112 and 113. g The tube isnornlally held in its circuit closing position, corresponding to the position shown in Fig. 4, by a thermally responsive latch bar 122. The upper end of 7 this latch bar carries a screw 123 which is adapted to engage over the edge'of a hook 124 dependingifrom the right/hand end of the rocker plate 115. Such latch bar, Fig. 5, consists of afbi-metallic. strip having its lower end anchored to a block of insulation 125, and having its intermediateportion subjected tothe'heating action of a res st ance element 126. This resistance element preferablycornprises a metallic cylinder secured at its rear endto an insulating block 1128 and having diametrically opposite slots 129 out therein, through which passes the bi-metallic strip 122, these? slots being sufficiently large so that in no point ofthe fiexure of the strip 122 will it contact with the shell or cylinder. Disposed withinthis cylinder is a sleeve 131 of insulation which is confined the-.resistance material,

thereto, and the front end of this'stack engages with a metallic compressing disk 133.

-The latter disk has a stem 134 supported in a threaded cap 135 which screws over the threaded end'of the cylinder 126. By screwing this cap inwardly or outwardly on the end of the cylinder, the pressure exerted on the carbon disks, and hence the resistance through such disks, can be varied to secure any desired heat transmission to the thermostatic bar 122. For establishing electrical connection between this thermostatically controlled cut-out switch and the exterior circuits, three

terminals

137, 138 and 139 are mounted on the insulating'panel 95. The first of these terminals 137 is connected through a flexible conductor 141 with the switch contact 112. The second of these ter- .the other contact 113 of the circuit breaking switch '111. It will be observed that current conducted to the terminal' 137 from an outside circuit will pass through conductor 141 to the switch and thence through such switch, assumingit to be tripped downwardly to the right to its circuit closing position, down through wire 146 to the binding post 145. From this point, part. of the current will be conducted up through the.

thermostatic latch bar 122, thence through the carbon disks 132, pressure disk 133, casing 126 and binding post 144 and wire 142 to terminal 138. Part of the current conducted from the switch through conductor 146 to binding post 145 will also pass through wire 143 to the other terminal 139.

The Several control circuits of the. system 'sh0wnin Figs. 1 and 8, I have. for facility u of explanation, shown the motor circuit or main supply circuit, in heavy lines, and the .ignition circuit in light I The current for operating the system is taken from the usual house lighting circuit, the two

wires

151 and 152 representing leads from such a circuit. For facility in describing the circuit connections, the wire 151 may be considered a common or live wire with which the main operating units ofthe system are normally connected. The burner motor 14 has one of its terminals permanently connected to this line, and the fuel valve motor 48 also has one of its terminals permanently connected to this line through wire 153. A wire 154 taps oif this common wire 151 and enters the control box where it has connection with the terminal 109. This terminal connects through flexible conductor 108 with contact 86 of the ignition switch. With the switch in its closed position, corresponding to the normal non-operating condition of the burner, the circuit continues through the switch and through conductor 108 to terminal 110. From this terminal a wire 155 extends to the solenoid winding 23 of the gas valve 22. A wire 156 taps ofl this wire 155 and connects to one side of the primary winding of the ignition coil 24. It will thus be seen that when the burner is not functioning the four main operating units, consisting of the burner motor 14. the fuel valve motor 48, the-gas valve solenoid 23 and the ignition coil 24, are all in direct connection with the live wire 151 of the supply circuit. To facilitate the explanation of the circuit I have shown the room thermostat 28 as being interposed in the wire 152 of this supply circuit, but it will be obvious that such thermostat might be interposed in the wire 151.

Tracing through the other side of the circuit from the room thermostat 28, the wire 152 is extended into the control box 47 where it makes connection with the terminal 137.;

mally latched down in closed position, and

hence the circuit continues from the other s'witch contact 113 through. wire 146 to the binding post 145 at the base end ofthe thermostatic latch. Here the ci-rcuit divides, part of the current flowin through wire 143, and terminal 139 to a wire 157 which connects to the solenoid 23 of the gas valve 22. A v

branch wire 158 taps off this wire 157 and connects to the other side of the primary winding of the coil 24, so that this coil is energized simultaneously with the energize.- tion of the solenoid winding 23. From the binding post 145 the other art of the circuit. continues up through t e thermostatic the other side of the burner motor 14, a

I branch wire 161 tappin off the wire 159 and --whatever current flows to the gas valve so1e-' vment as it ensures asubstantially constant connecting with the ot er side of the fuel valve motor 48 so that both motors are connected in parallel. It will be seen from the foregoing that by virtue of this divided circuit, branching each way from. the binding post 145 at the base end of the latch bar,

noid 23 and to the ignitioncoil 24 does not pass through the resistance disks 132, whereas all of the current flowing tothe burner motor 14 and to the fuel valve motor 48 passes through such disks. As will herein after appear, this is the preferred arrangeflow of current through the resistance" disks whereby the time interval for heating the I thermostatic latch bar to its unlatching temperature can be .closely calculated, but, if

"desired, the current flow to the gas valve solenoid and to the ignition coil can. also be arranged to pass through the resistance disks. The stack or combustion responsive of the com ustion responsiveswitch direct- 1% in shunt across'the resistance disks 132 t r ough the

wires

162 and 163. When the burner is not operating the stack switch 35 normally stands in open position and hence the shunt across the resistance disks is open at this time.

In the operation of the system it seen that with the room thermostatic switch 28 in its open position the supply :circuit to the system will be interrupted, but as soon as this room thermostatic switch is moved to its closed osition, by a predetermined lowering: of t e temperature in the house,

ing' up through the circuit is completed throu h thisside of the line to the terminal 137 o the control box. From here the circuit continues through the safety switch 111.to the binding post 145 where it-divides, as before de-' scribed, part of the currentflowing' through wire 157- to the gas valve solenoid 23. and ignitlon coil 24 and part of the current flow- 138 and wire 159 to the burner motor. '14 and fuel valve moter 48. As previously remarked, with theburner inert, the four op-' crating elements-are all normally connected to the ve or common side 1510f the supply circuit, and hence when the room=thermostaticswitch closes all four of these operfatv ing units are simultaneously energized. Both

motors

14 and 48 instantly begin to operate,

the burner motor 14 projecting fuel and air into thefurnace, and the shut-off valve mothe thermostatic latch bar 122, reslstance. disks; 132, wire -142,terminal toroperating to open the fuel valve and thereby permit the continued supply of .fuel to the .fuelchamber as fuel is drawn therefrom. The solenoid 23 of the gas valve 22 being simultaneously energized, the gas valve is caused to open to discharge gas through pipe 21; and the primary winding of the ignition coil being also energized at this time, thesecondary winding thereof producesa spark at the sparking electrode, thus igniting the. gas jet issuing from the pipe 21.

This preliminary ignition operation actually precedes the delivery of the fuel to the combustion chamber owing -to the inertia of the burner motor and the slight delay incident to the atomizing pump 16'comintg up to operating speed. Hence-the gas ame is ex- 'isting inthe combustion chamber when the fuel is projected into the chamber, whereby ignition of, the fuel can occur instantly without the possibility ofia charge of fuel accumulating in the furnace before ignition occurs.

Simultaneously with the opening. of the fuel valve, the screw 81 is caused to move upwardly away from the rocker 84, whereby the weight 96 and spring 97 become efiective on the ignition switch, tending to move the latter to its open position. This movement ofthe switch is very gradual, being retarded by the dash-pot 101, so that an appreciable time interval elapses after'the raising of the screw 81, before the switch tips to open position i. e. that position where the globule of mercury rolls to the left away from: the

con tacts

86 and 87. Preferably, the apparatus is set for an i nition interval of from 15 to. 25 seconds.

is may be lengthened or shortened as desired by threading thescrew 81 up or down in the arm'7 9 to thereby vary the angular position which the mercury tube normally occupies in its closed position, a greater inclination in this direction requiring a longertiine interval for the switchto move to open position, and a lesser inclination requiring a shorter time interval. It will be evident thatwhen the ignitionswitch moves to open. position the circuit through the wire 155 is broken and hence the gas valve 22 automati cally closes and the ignition .coil 24 ceases producing its spark at the sparking electrode 27. The purpose of definitely interrupting the ignition operation after .a predetermined period of time is'to revent the possibility of" i the furnace accumu ating a large charge of combustible mixture and then being fired by a tardy operation of the ignition apparatus I with the consequent possibility of an explosion. During this initial operation of the burner, all of the current supplied to the burner motor 14 and .to the fuel valve motor 48 is passing through the resistance disks 132,

. inasmuchfasjthe stack switch35 is open at this time Hence these disks are being gradually heated and are transmitting their heat to the thermostatic latch bar 122.' The heat transmitted to the latch bar during the initial operation of the burner is not suflicient, however, to cause such latch bar to flex to its releasing osition, the arrangement being such that eat must be conducted to this to be tipped to closed position. This placessuch switch as a shunt across the resistance disks 132 whereby substantially the entire current supply for the two

electric motors

14 and 48 is diverted through the lower resistance path afforded by the stack .switchQ Thereupon the heating effect of the resistance element is almost entirely eliminated, with the result that the transmissionofheat to the thermostatic latch bar is discontinued and this latch bar hence remains in its latching engagement with the hook 124, thereby holding the safety switch inits normal closed position.

Assume, on the other hand, that through the existence of some abnormal condition the fuel has failed to ignite at the end of the ignition interval and that the burner is still projecting fuel into the combustion chamber, threatening to flood the same'and cause the waste of a large uantity of fuel. At this time the absence 0 any temperature of combustion in thefurnace and stack will result in the stack switch 35 remaining in its open position. Hence all of the current supplied to the two

motors

14 and 48 will continue to pass through the carbon disk resistance ele-.

ment. The heat transmitted to the thermostatic latch 122 will cause this latch gradually to flex outwardly, until, after the lapse of a predetermined time interval the screw 123 will clear the hook 124, allowing the safety switch to rock to open position, thereby breaking the circuit of the entire system through conductor 146. The apparatus is so adjusted that the circuit breaking function of the safety switch will not occur until some time after the ignition apparatus has gone through its igniting operation, thus giving the ignition apparatus full opportunity to ignite the fuel before the safety cut-out will operate. Different adjustments of this cut-out switch for different time intervals of operation can be obtained by screwing the cap 135 inwardly or outwardly along the cylinder 126, and by adjusting the screw 123 in' the lat-ch bar/122.

The safety cut-out will only be caused to ope out' will completely disconnect the system from the supply line untilthe householder manually tips the safety switch back to its closed position to latch the hook 124 under the screw 123 of the thermostatic latch bar. At such time the householder can examine the apparatus to correct the abnormal condition which brought about the operation of the cut-out switch. 1

One such condition which will, of course, result in failure of ignition is the exhaustion of the fuel supply. If this should occur during the normal operation of the burner while the furnace was being heated, it is desirable that the needless rotation of the burner mo tor be stopped. Such will automatically follow at this time through the action of the stack thermostat 38, which will gradually cool off and cause the stack switch to move to open position. This of course opens the shunt across the carbon disk resistance element with the result that the current flow of v and thereby trip the safety switch 111.

Assuming that the burner is operating under normal conditions, when the temperature of the house, room or other point being heated is brought back to the predetermined maximum temperature, the room thermostat will 3 open the main circuit wire 152 and the entire system will then cease operating. With the deenergization of the fuel valve motor 48,

consequent upon the opening of the circuit wire 152, the fuel valve will automatically move to closed position, thereby positively cutting ofl further flow of fuel to the burner and preventing any possibility of leakage, and in such movement to closed position the fuel valve through the arm 7 9 and screw 81 will reset the ignition switch to its closed position, preparatory to the next cycle of operation of the system.

This action of the fuel valve in resetting the ignition switch to closed position every w.

time the control circuit is broken safeguards the burner against various abnormal conditions. For example, if the source of power should fail while the burner is in operation, the ignition switch will be immediately reset to closed position so that as soon as power comes back on the line the ignition operation will recur with the restarting of the burner motor. I

It will be observed that the entire system operates on the voltage of the house li hting circuit, or on the voltage that is supp ied to the burner motor, thus avoiding the expense of a step-down transformer for the control system and the possibility of such a transformer burning out. The use of switches of the mercury tube type in the various control'circuits is one of the features that makes the operation of the control system on thehigher voltages practical, these switches being capable of handling the higher voltages without injurious arcing and without requiring the complicationof quickvto gas burning installations. The burner mobreak mechanism.

In Fig. 9 I have illustrated. this same general arrangement of control system adapted tor 14 is eliminated from the control system, as well as the solenoid-operated gas valve 22-23, otherwise the system is generally similar to the arrangement illustrated in Fig. 8. The gas is discharged into the combustion chamber through any suitable burner nozzle 166, in the arrangementshown this nozzle discharging through an air induction tube 167 entering thefront of the combustion chamber. The flow of gas to this nozzle is controlled by the motor operated shut-' room thermostat 28 closes, with the result that gas is discharged from the burner nozzle 166.

The ignition circuit is energized simultaneously therewith for creating an -igniting spark at the electrode 27, this ignition operation being automatically interrupted after the lapse of a predetermined time period by the gradual tipping of the ignitibn switch under the control of the dash pot 101, as before described. In the event of failure of ignition or cessation of combustion, the stack switch 35 will either remain open or reopen and hence the safety cut-out switch 111 will break the entire control circuit. With the opening of the control circuit, consequent upon the open- 1ng of the room thermostatic switch 28, or of the safety cut-out switch 111 the valve ele 'ment of the motor operated shut-off valve will return to its seat, thereby stopping the flow of gas to the nozzle.

While the construction and arrangement of control system hereinbefore described is in most respects the preferred embodiment of my invention, it will be understood that such embodimentis merelyexemplary and that numerous changes and rearrangements may be made therein without departing from the fundamental features of the invention.

What I-claim as my invention and desire to secure by Letters Patent, j

1.- In a control system for burners, the combination with aburner motor, of a main supply circuit therefor, thermally responsive means controlling said supply circuit, an elec-.

- tric'ally operated control unit adaptedto be energized upon the energization' of said supi ply circuit and comprising a moving element,

' having'movement in two directions, an-ignition circuit, an ignition switch controlling the energization of said ignition circuit from said supply circuit, said ignition switch normally being in closed position during the nonoperating intervals of the burner,-and means for controlling the position of. said 1%11113101] switch, said means being operated y the movable element in one direction only.

2. In a control system for burners, the combination of a rotating armature electric motor, a circuit therefor, ignition apparatus, an ignition switch controlling said' ignltion apparatus, means operatively connecting said motor with said ignition switch whereby when said motor is deenergized said switch is caused to return to and to remain in closed position, and when said motor is energized said switch is permitted to move to open position with a motion independent of the mo tion of said motor, and means for retarding the motion of said switch to open position.

3. In a control system for burners, the com- .bination of a fuel pipe supplying fuel to the e1 pipe, ignition burner, a valve in said apparatus for igniting-the fuel comprising an ignition coil having primary and secondary windings, a circuit for said primary winding, aswitch in said circuit, electrically operated means for opening said valve, cir- V cult connections for mamtammg said electrlcally operated means energized during the operation of the burner, andmeans for transmitting the motion of said valve to said switch for-moving the latter to closed position.

. '4. In a control system for burners, the combination of a fuel pipe supplying fuel to the burner, a .shut-ofl valve in said fuel pipe, ig-

nition apparatus for igniting the fuel com prising a coil having primary and secondary.

windings, a circuit for said primary wlndmg, a switch controlling sa i'd circuit, said switch normally tendilig to move to open position, electrically operated means for opening sa1d valve, spring means for closing said valve,- s'and means responslve to the motlon of said valve and cooperating with said switch for holding the latter in closed position while the system is non-operating. v

i 5. In a control system for burners, the combination of a fuel pipe supplying 'fuel to the burner, a shut-oif valve in said fuel pipe,

ignition apparatus for igniting the fuel comprismg a coil having primary and secondary I windings, a circuit for said primary winding,

a switch controlling said circuit, said switch normally tending to move-to. open posltion,

valve, spring means for closing said valve, means for transmitting the :motion of said valve in one direction to said switch'for moving thelatter to closed position, and means operating independently of said electrically said switch to open position.

6. In a controljsystem for burners, the

combination of a fuel'pipe supplying fuel to electrically operated means for opening said operated means for retarding the motion of the burner, a shut-ofi valve in said fuel pipe, ignition apparatus for i iting the fuel comprising a coil having primary and secondary windmgs, a circuit for said p ary winding, a mercury tube type of switch in said circuit, said switch 'normally tending to move to open position, a rotating armature type of electric motor mechanically connected to open said valve, spring means for closing said valve, means for transmitting the motion of said valve in one direction to said Q switch for moving the latter to closed position, and means operating independently of said motor for retarding the motion of said switch to open position.

7. In a control system for burners, the combination of a fuel pipe supplyin fuel to the burner, a shut-off valve insai fuel pipe, ignition apparatus for igniting the fuel comprising a coil having primary and secondary windings, a circuit for said primary winding, a switch controlling said circuit, said switch normally tending to move to open position, a rotating armature t of electric motor mechanicall conn to move said valve to open position, s ring means for closing said valve, means or transmitting the closing motion of said valve to said switch for moving the latter to closed position, and a dash-pot for retarding the motion of said switch to open position upon the opening of said valve.

8. In a controls stem. for burners, the

combination with a el pipe supplyin fuel to the burner, of a g mam circuit, a thermostatic switch controlling said maincircuit,

-' the temperature of the area said thermostatic switch be' responsive to ing heated, a burner motor connectedto said main circuit, a secondary motor connected to said'main circuit, a valve-interposed in said fuel pipe, means for actuatin said valve by said secondary motor,.sai motor 0 rating to a stalled condition for holding said valve open, an ignition circuit comprising ignition means, an ignition switch controllm tion of one side of said'ignition circuit to one side of said main circuit, and means responding to the-motion of said valve for moving said ignition switch to one position.

9. In burner control apparatus, the combination of a main circult, a thermostatic switch interposed'in one side of. saidmain circuit, said switch being responsive to the temperature of the area being heated, a burner motor connected across said main circuit, a motor operated fuel valve connected across said main circuit, an ignition circuit comprising ignition means, an ignition switch controlling the connection of one side of said the connecsaid fuel valve being adapted to be operate to a stalled condition, an ignition switch having one contact connected with one side of said main circuit, means responding to said motor operated fuel valve for actuating said ignition switch, an ignition circuit leading from the other contact of said igmtion switch and connecting with the other side of said main circuit, and an ignition. coil having its primary winding connected to said i ition circuit;

11. n burner control apparatus, the com bination of a main-circuit, a thermostatic switch interposed in one side of said main circuit, said switch being responsiv to the temperature of the area bein heated, a burner motor connected across sai main circuit, a motor operated fuel valve connected across said main circuit, an ignition switch having one contact connected with one side of said main circuit, means responding to said motor operated fuel valve for actuating said ignition switch, an ignition circuit leading from the other contact of said ignition switch and circuit, an ignition coil having its primary wvindingconnected to said ignition circuit, and an electrically operated gas'valve connected to and opening with the energization of said ignition circuit.

12. In a control system for burners, the

combination of an ignition circuit, an ignition switch controlling said circuit and tending to'move to open position, an electric control motor, and means operatively connected with said. electric motor and with said switchto hold the latter in closed position whenever said motor is deenergized, said motor, when energized, rendering said holdin means nonefiective whereby permit said switch to move to open position.

13. In a control system for burners, th

combination. of an ignition circuit, an ignition switch controlling said circuit, said switch tending to move to open position, an electric control motor, means for maintaining said motor energized during the operation of the burner, independently of the opening of said ignition switch, and a one-way operating connection between said control motor and said switch operative to transmit motion to said switch in only one direction, said operating connection permitting said switch to move in the opposite direction while said motor remains energized during the operation of the burner.

14- In a control system for burners, the

connecting with the other side of said main combination of an ignition circuit, an ignition switch controlling said circuit, said switch tending to move to open position, an electric motor, circuit connections for maintaining said motor energized during the,

operation of the burner, and a one-way operating connection between said motor and said switch operative to transmit motion to said switchonly in a direction to close the same, said operating connection permitting said switch to move to open position while said motor remains energized during the operation of the burner.

I 15. In a control system for burners, the combination of an ignition circuit, an' ignition switch controlling said circuit, said switch tending to move to open position, a spring arranged for holding said switch in closed position when the system is deener gized, and an electric motor operative when the system is energized to overcome said spring for permitting said switch to move to open position.

16. In a control system for burners, the combination of an ignition circuit, an ignition I switch controlling said circuit, said 'switch tending to move to open position, timecontrolled means governing the movement of said switch to open position, an electric motor, and means actuated thereby and effective whenever the motor is deenergized to hold said switch in closed position, but removing its restraint from said switch when the motor is again energized so that the movement of the switch to open position willbe governed solely by said time controlled means.

17. In a control system for burners, the combination of a main circuit, an ignition circuit, anignition switch controlling said latter, circuit, means tending to move saidswitch to open position, time-controlled means governing the movement of .said switch to open position, a spring operatively connected for moving said switch to closed position, and an electric motor operative when energized by said main circuit to overcome said spring for permitting said switch to move to closed position under the control of said time-controlled means.

18. In a control system for burners, the combination of a main circuit, an ignition circuit, an ignition switch controlling said latter circuit, means tending to move said switch to open position, a dash-pot for retarding the movement of said switch to open position, a rotating armature control motor responsive to said main circuit, a rack adapted to be moved in one direction by said motor, a spring for moving said rack in the opposite direction, and means for transmitting the latter movement of said rack to said ignition switch whereby said switch is moved to closed position when said control motor is deenergized.

, 19. In a control system for burners, the

combination with a burner motor, of a. main supply circuit therefor, thermally responsive ment having movement in two directions, an

ignition circuit, an ignition switch controlling the energization of said 1gn1t1on c1rcu1t from said supply circuit, means utilizing the movementof said-movable element in one direction for moving said ignition switch to closed position, said switch being retained thereby in closed position during the non-operating intervalsof the burner, and means operating independently of said electrically operated control unit for retarding the movement of said switch to open positions 20. In a control system or burners, the combination of ignition apparatus comprising an ignition coil having primary and secondary windings, a circuit for said primary winding, a mercury tube type of switch in said circuit, said switch normally tending to tip to open position, a rotating armature type of electric motor adapted to operate to a stalled condition, thermostatic means con-.

trolling said electricmotor, a one-way operating connection between said motor and said switch operative to transmit motion to said switch only in a direction to close the same, said operating connection retaining said switch closed during. the non-operating intervals of the burner, and dash-pot means for delaying the motion of said switch from its closed position to its open position.

21. In a control system for burners, the combination of a main circuit comprising first and second wires, a burner motor, an oil valve, a control motor for actuating said oil valve, both of said motorsbeing connected in parallel across said main circuit, a room thermostat connected directly in said main circuit,.a circuit breaker interposed in said main circuit between said room thermostat and said burner motor, said circuit breaker comprising an electrically heated element operatively connected to release said circuit breaker, said electrically heated element being connected in series in said first main circuit wire to have the motorcurrent pass therethrough, a combustion responsive switch connected to establish a shunt across said electrically heated element, an ignition circuit having one side thereof connected to said first main circuit wire on the line side of said electrically heated element, an ignition switch connecting the other side of said ignition circuit,v to the second main circuit wire, and means actuated by said control motor for operating said ignition switch.

22. In a control system for burners, the combination of a main high voltage circuit, a burner motor, an oil valve, a control motor for actuating said oil valve, both of said circuit, a circuit breaker interposed in said main circuit between said room thermostat and saidtburner motor, said circuit breaker comprising an electrically heated element opbreakei'. said electrically heated element being connected in series with one of said motors to have the motor current pass there through, a combustion responsive switch connected to establish a shunt across said electrically heated element, an ignition circuit having one side thereof connected to said main circuit on the motor side of said circuit breaker, an ignition switch controlling said control motor for 'said ignition circuit, and means actuated by operating said ignition switch. a

23. In a control system for burners, the

' combination of ignition apparatus comprising an ignition coil having primary and secondary' windings, a circuit for said primary winding, an ignition switch in said circuit, said switch normally tending to m ove to open position, a rotating armature type of electric motor mechanically connected to move said switch to closed position, circuit connections for said motor for maintaining the latter energized during the operation of the burnor and after said ignition circuit has been opened, said switch remainingv in closed position during the non-operating intervals of the burner, thermostatic means cooperating with the circuit connections for said motor for controlling the operation of the motor, said motorwhen energized operating to a stalled condition and permitting said switch to continue to move thereafter toward its open position, and means for retarding the motion-of said switch to open position.

. combination of a fuel valve,

24. In a control system for burners, the means biasing said valve to closed position, a rotary electric motor arranged when'energized to move said valve to and maintain it in open positionaga nst said biasing means, a power multiplying gear train connecting tho rotor of said motor with said valve and operable in one direction by said biasing means, means for stalling said m'otorwhile *ener 'zedwith the valve in open position, where y said motor will maintain the valve opened, said biasing means beingsufiicient to overcome theinertia of the motor and gearing train and move the valve to closed position when the motor is deenergized, an ignition circuit, an ignition switch controlling said circuit, and means utilizing the motion of said valve for moving direction through substantially same eratively connected to release said circuit\ number of revolutions, means utilizing the rotation of said motor inthe forward direc- .tion to move said fuel valve to open position, and means utilizing the motion imparted by said spring means in rotating said motor in the backward direction for moving said ignition switch to closed position. v

' 26. In a control system for burners, the combination of an ignition circuit, an ignition switch controlling said circuit, a fuel valve, a rotary electric motor operating when energized to rotate in a forward direction through a substantially predetermined number. of revolutions, spring means functioning when said motor is deenergized to rotate the motor backwardly in the opposite direction through substantially the same number of revolutions, means utilizing the rotation of said motor in one direction to move said fuel valve to one position, and means utilizing the motion imparted by said spring means in rotating said motor in one direction to move said ignition switch to oneposition.

27. In a control system for burners, the combination of an ignition circuit, an ignition switch controlling said circuit, a rotary electric motor operating when energized to rotate in one direction through a substantially predetermined number of revolutions,

s rin means functionin when saidmotor is deenergized to rotate the motor backwardly'in the opposite direction through substantially the same number of revolutions, and

means utilizing the motion imparted by said spring means in rotating the motor in one direction for controlling said ignition switch.

MARSHALL H. BRADEN.