US2924270A - Control apparatus - Google Patents

Description

Feb. 9, 1960 F. T. DEZIEL CONTROL APPARATUS Filed Nov. 27, 1957 N "8 In N LINE SWITCH com 3 Sheets-Sheet 1 INVENTOR.

FRED T. DEZIEL j Md/Jw A TTOR/VE Y Feb. 9, 1960 F. T. DEZJEL CONTROL APPARATUS 3 Sheets-Sheet 2 Filed NOV. 27, 1957 INVENTOR,

I FRED T DEZIEL ATTORNEY Feb. 9, 1960 F. 'r. DEZlEL 2,924,270

CONTROL APPARATUS Filed Nov. 27, 1957 3 Sheets-Sheet 3 LINE SWITCH CONTROLLER 18 GEIGER TUBE 'INVENTOR. FRED I DEZIEL ATTORNEY tection portion thereof.

United States Patent CONTROL APPARATUS Fred T. Deziel, Bloomington, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application November 27, 1957 Serial No. 699,235

Claims. (Cl. 158-125) This invention is concerned with an improved control apparatus and particularly with a control apparatus utilizing a Geiger tube type condition sensor in conjunction with a quenching circuit and a safe-start relay.

As is well known, a Geiger tube may be used to sense the presence of various conditions. For example, flame at a fuel burner unit. The Geiger tube may be either of the self-quenching type or of the non-selfquenching type. If of the non-selfquenching type, it is necessary to provide a quenching circuit, with the Geiger tube and the quenching circuit interconnected in mutual controlling relationship such that upon the Geiger tube being ionized, a signal is fed to the quenching circuit, and the quenching circuit in turn quenches, or dionizes, the Geiger tube.

This quenching circuit utilizes a hot cathode type discharge device and upon the initial application of voltage to the apparatus it is desirable to provide a means to delay the application of operating voltage to the Geiger tube until the hot cathode discharge device becomes heated to its operating temperature, to thereby be in a condition to quench the Geiger tube. Such a construction prevents sustained discharge through the Geiger tube during the Warmup period of the quenching circuit and thereby prevents a period of instability of the Geiger tube. This feature of providing means to delay the application of operating voltage to the Geiger tube is shown in the copending application of Robert O. Engh, Serial No. 646,- 125, filed March 14, 1957.

Such a Geiger tube and associated circuitry can be utilized with a burner control apparatus as the flame de- It then becomes desirable, on initial call for operation of the burner, to check the operation of the flame detector before allowing the fuel to be admitted to the fire box. This is accomplished by providing a safe-start relay which initially simulates the presence of flame, with the apparatus including interlocking circuit means which insures that the main burner control relay is not energized unless the flame detector responds to the simulated presence of flame.

Such a construction is particularly advisable in the case of an electronic flame detector which utilizes hot cathode type discharge devices. this construction can be seen by assuming that a power failure should occur. The discharge devices of the electric flame detector then cool and the flame detector assumes a non-flame condition. Upon the subsequent restoration of power to the apparatus, the flame detector remains in the non-flame condition since the discharge devices have not as yet heated to operating temperature. There is no assurance, however, that a fault does not exist in the flame detector which will subsequently cause the flame detector to assume a flame condition, independent of the actual presence of flame, once the discharge devices are heated. If such a fault does in fact exist, the flame detector assumes a flame condition when the discharge devices are heated, thus indicating the pilot flame has again been reestablished at the fuel burner The advisability of 2,924,270 Patented Feb. 9, 1960 2 unit. The main valve then opens and if the pilot flame has not been established, unburned fuel floods the fire box.

By providing the safe start relay, which relayfirst simulates a flame and upon the flame detector responding to the simulated presence of flame then removes the simulated flame to cause the flame detector to assume a flame and then no-flame condition, and furthermore providing means to insure that the apparatus must go through this sequence before the main valve can be energized, the proper operation of the flame detector is checked and if such a fault does exist, the main valve is not energized.

The present invention is directed to an arrangement whereby the safe start relay, as above mentioned, not only checks the operation. of the flame detector but also prevents application of operating voltage to the Geiger tube until the quenching circuit is in a condition to quench the Geiger tube. As above mentioned, this prevents a sustained discharge to the Geiger tube during a warmup period of the quenching circuit and thereby eliminates a period of instability of the Geiger tube.

While the modifications of this invention are shown in conjunction with the flame sensor, it will be readily understood that the present invention can be equally applied to the sensing of any condition towhich a Geiger tube is sensitive.

It is therefore an object of the present invention to provide an improved condition responsive control apparatus utilizing a Geiger tube and a quenching circuit therefor and utilizing a safe start relay, with the Geiger tube, quenching circuit and safe start relay interconnected to provide for a delay of the application of operating voltage to the Geiger tubeand to first provide for a simulated presence of a condition to cause the safe start relay to be operated, and second to cause an operating voltage to be applied to the Geiger tube and remove the simulated presence of the condition.

Other objects of the present invention will be apparent to those skilled in the art upon reference to the following speciflcation, claims and drawings, of which Figure 1 is a schematic showing of the present invention associated with a fuel burner unit, disclosing a burner control apparatus utilizing the present invention,

Figure 2 is a modification of a portion of the apparatus, wherein only the Geiger tube, the quenching circuit and the safe start relay have been shown for purposes of simplicity, and

Figure 3 is a showing of a further modification of the present invention.

Referring specifically to Figure 1, the reference numeral 1t designates a fuel burner unit having a main burner 11, a pilot burner 12, a main valve 13, a pilot valve 14, and ignition means 15.

Reference numeral 16 designates a Geiger tube having a cathode .17 and an anode 18. This Geiger tube is positioned to be subjected to the flame at the fuel burner unit and upon being subjected to a flame, the Geiger tube ionizes to pass a current to an electronic network including electron discharge devices 19 and 25. The discharge device 19 is a gas filled type of discharge device and includes an anode 20, a control electrode 21, a cathode 22 and a further electrode 23. This discharge device is a portion of the quenching circuit for the Geiger tube 16 and the cathode of this discharge device must filed June 21, 1956. This interconnection issuch that the signal voltage applied to the control electrode 29is applied directly from the quenching'circuit whereasthe signal voltage applied to the control electrode 30 is integrated by means of the network including capacitor 31 and resistor 32.

The discharge devices 19 and 25, as well as the Geiger tube 16, receive their operating voltage from a transformer 33 having a primary winding 34'and secondary windings 35 and 36. The output of the flame detector includes a flame relay 37 having an actuating winding 38 and switches 39, 40 and 41. The switches 39 and 40 are normally open switches and the switch 41 is a normally closed switch. Upon energization of the winding38, switches 39 and 40 close whereas switch 41 opens. l

The flame relay 37 cooperates with a further relay 42, which can be designated the safe start relay. This relay includes an actuating winding 43 and normally open switches 44 and 45 as well as the normally closed switch 46. Upon energization of the winding 43, the switches 44 and 45 assume a closed condition whereas the switch 46 assumes an open condition. a

The reference numeral 47 designates a main burner control relay having an actuating winding 48 and normally open switches 49 and 50 as well as the normally closed switch 51. Upon energization of the winding 48, the switches 49 and 50 assume a closed position and the switch 51 assumes an open position.

The reference numeral 52' designates a safety cutout means in the form of a bimetal operated safety switch. This safety switch is provided with an actuating heater 53 which heats bimetal 54. Bimetal 54, when hot, warps to the left and causes the switch 55 to open, as shown by the arrow labeled H. Upon subsequent cooling of the bimetal, the reset button 56 may be depressed toreset the safety switch 52 to the condition shown in Figure l.

The control apparatus shown in Figure '1 includes power input terminals 57 and 58 which are'adapted to be connected to a source of alternating voltage, not shown. This source of voltage supplies energizing voltage to the components of the control apparatus as well as to the fuel burner unit and is controlled by a line switch 59 and a controller 60. This controller 60 may be a manual controller or an automatic controller responsive to a condition such as temperature which is in turn. controlled by operation of the fuel burner unit 10. Referring now specifically to the operation of the flame detector including Geiger tube 16 and discharge devices 19 and 25. As above mentioned, operating voltage is derived from transformer 33, and specifically the secondary windings 35 and 36 thereof. Winding 35 is provided with a rectifier 61 and a capacitor 62 which consists of a source of direct current voltage having the polarity indicated on capacitor 62. This winding is'provided with a tap which is connected to a further capacitor 63 and a further rectifier '64 and then to the lower end terminal of the secondary winding 35. This circuit provides a source of biasing voltage, of the polarity shown on capacitor 63, which tends, to bias discharge device 25 substantially to cutoff. The cathode 27 of this discharge device isconnected to the positive plate of capacitor 63 and the negative plate of this capacitor is connected through resistor 65 to control electrode29 and through resistor 66 to control electrode 30. The

anode of this discharge device 25 isconnected through the winding 38 of the flame relay 37 to the positive terminal of capacitor 62, thereby applying apositiveoperating voltage to the anodeof this discharge device,

tor 62 and the cathode of this discharge device is connected through a network including resistors 68, 66, 65, and 32 and capacitor 31, and further through rectifier 64 to the negative plate of this capacitor 62, thereby applying an operating voltage, to the anode and cathode of discharge device 19.

Upon discharge device 19 being rendered conductive, capacitor 72 discharges through resistor 67 and the anode and .cathode of discharge device 19 and back to the negative plate of capacitor 72. Upon discharge of capacitor 72, capacitor 62 begins to recharge capacitor 72,

with current flowing from the positive plate of capacitor 62 to capacitor 72. At this point the current divides into two paths. The first path consists of the series connected resistors 68 and 65. The second path consists,

of resistor 32 connected in series with the parallel connected resistor 66 and capacitor 31., The, current flow circuit is then completed tive plate of capacitor 62. p v

It willbe recognizedthat in the above traced circuit the first branch consistingof resistor 68 and resistor 65 applies a positive voltage to the control electrode 29 of discharge 25, this voltage being directly applied to this control electrode. However, the positive voltage applied to the control electrode 30 is integrated by means of the network including capacitor 31 and therefore this voltage is delayed or integrated with respect to the voltage applied to control electrode 29. As explained in the above mentioned co-pending Fred T. Deziel application,

this discriminates against or eliminates the efi'ect of the inherent background count of the Geiger 'tube 16.

Geiger tube 16 and discharge device 19 are connected 1 in mutual controlling relationship, this relationship being through a resistor 67 to the positive plate of the capacii Assume for the moment that safe the energized position to thereby open the switch 46 and 1 controlled by the switchmeans of safe start relay 42. The cathode 17 of Geiger tube 16 isconnected directly to the control electrode 21 of discharge device 119. The 1 anode 18 of this Geigertnbe is connected to the normally open switch 45 of safe start relay 42. Therefore, with relay 42 de-energized the Geiger tube 16 is not connected in controlling relation to discharge device '19 nor is an Operating voltage applied to the Geiger tube. With relay 42 de-energized, the control electrode 21 of discharge device 19 is connectedto theanode 20 through a resistor 69 and through the normally closed switch 46 of relay 42. This connection simulates the presence of flame at the fuel burner unit 10 and causesdischargedevice 19" to be conductive, for -the reasons to be described.

A biasing means for dischargedevice 19 is provided from-the secondary Winding 36 of'transformer 33 in combination with a rectifier 70 and a capacitor 71. This circuit provides for biasing discharge device 19 substantially to cutoif. Winding 36 also energizes heater 24 of, discharge devic 19. 9 l

start relay 42 is in toclose-the switch 45. Further assume that there is no flame present at the fuel burner, unit 10. In this condition the discharge devices-19 and 25 are non-conductive due to the cutoif bias supplied to the control electrodes thereof. The Geiger tube 16 has an operating voltage applied thereto and is in a condition to sense ,a flame at the burner unit 10. Ha flame is now established at the burner unit 10, the Geiger tube 16 ionizes to pass currentthrough a circuit which can be traced from, the t positive plate of capacitor 172 through resistor.67,. conductor 72, switch 45, conductor 73, Geiger tube116, conductor 7 4,"resistor 75, rectifier 70, transformer winding 36 and conductors 76 and 77, back to the negative plate of capacitor 172. At this point the current path splits into two branches; The first branch includesthe series connected resistors 68 and 65. The second branch includes resistor32 connected in serieswiththe parallel connected resistor 66 and capacitor 31. The charging 1 current flow circuit then continues through rectifier 64 to the lower plate of capacitor 62. It can be seen from 1 through rectifier 64 to the negaw this current flow path that a voltage is developed across resistor 75 which opposes the cutofi voltage developed across capacitor 71 and thereby causes discharge device 19 to become conductive. Discharge device 19 is a high current conducting device, relative to the current which is conductive by Geiger tube 16, this device now becomes conductive and discharges capacitor 172 which is effective to substantially drop the voltage across the electrodes of Geiger tube 16 and to thereby quench this tube. This discharge circuit for capacitor 172 has been previously traced and it can be seen from this circuit that a voltage is also developed across the resistors 65 and 68 as well as the resistors 32 and 66, resistor 66 being shunted by capacitor 31.

The Geiger tube 16 has now been quenched as above described and the voltage developed across resistor 75 which initiated discharge of device 19 is now no longer present.

A short time period must elapse to recharge capacitor 172 before this operating voltage is applied to the Geiger tube and to discharge device 19. This recharging circuit, as has been described, can be traced from the positive plate of capacitor 62 through capacitor 172. At this point the current branches into two circuits. The first circuit includes series connected resistors 68 and 65. The second circuit includes resistor 32 connected in series with parallel connected resistor 66 and capacitor 31; The recharging time of capacitor 172 determines the frequency or repetition rate at which the Geiger tube 16 is allowed to sense a flame at the fuel burner unit 10.

Upon capacitor 172 once being charged such that an operating voltage is applied through the Geiger tube, the Geiger tube again ionizes, due to the presence of fire at the fuel burner unit 10, and the above sequence of operation again takes place to once again apply a signal voltage to the network including resistors 32, 65, 66 and 68 and capacitor 31. After a suflicient number of these signal voltages pulses have been applied to the integrating capacitor 31, this capacitor charges such that a voltage appears on both of the control electrodes 29 and 30 at the same time and at this time the discharge device 25 becomes conductive to energize the winding 38 of the flame relay 37.

Turning now to the explanation of the complete control apparatus, the apparatus in Figure 1 is shown in a condition wherein alternating voltage is not applied to the power input terminals 57 and 58. If it is assumed that a voltage is now applied to these terminals and that line switch 59 is closed, the primary winding 34 of transformer 33 is energized through a circuit which can be traced from terminal 57 through line switch 59, conductors 78, 79 and 80, transformer primary winding 34, conductor 81, safety switch 52, and conductor 82 to the terminal 58. This connection energizes secondary windings 35 and 36 and operating voltages are applied to the .dis-

charge devices 19 and 25. Due to the fact that the safe start relay 42 is de-energized at this time, an operating voltage is not applied to the Geiger tube 16. As above explained, with relay 42 deenergized the control electrode 21 of discharge device 19 is connected through resistor 69 and through the switch 46 to the anode of this discharge device. After an initial time delay during which the cathode of discharge device 19 is heating, discharge device 19 becomes conductive and a voltage is developed on control electrodes 29 and 30 of discharge device 25 to cause this discharge device to in turn become conductive. This energizes the winding 38 of flame relay 37 to cause the switch 40 of this relay to close.

When this switch 48 closes, an energizing circuit is completed for the winding 43 of the safe start relay 42. This energizing circuit can be traced from the terminal 57 through line switch 59, conductors 78, 79 and 83, winding 43, conductor 84, heater 53, conductors 85 and 86, switch 51 of the main burner control 'relay' 47, conductor 87, switch 48 of flame relay 37, conductors 88 6 and 81, safety switch 52, and conductor 82 to the terminal 58. g

This above traced circuit energizing the. winding of safe start relay 43. It will be noted from the above traced circuit that in order for the winding of safe start relay 42 to be energized at this time it is necessary that main burner control relay 47 to be de-energized and that the flame relay 37 be energized. In this manner, the operation of the flame detector is checked since the flame is simulated and the flame detector has responded to this simulated presence of flame to energize the flame relay 37. Furthermore, in order for the flame detector to respondto this simulated presence of flame it is necessary that the discharge device 19 be operative. Therefore, the energization of flame relay 37 is indicative of the fact that the quenching circuit, including discharge device 19, is now in an operating condition. Therefore, although operating voltage is not at this time applied to the Geiger tube 16, the apparatus has checked to insure that the quenching circuit is operative before allowing the safe start relay 42 to be energized. Furthermore, it is impossible at this time for the controller to energize the main burner control relay 47 since the energizing circuit for this relay is broken at the switch 41 of the flame relay 37. This insures that the main burner control relay 47 may not be energized during the checking period 'of the apparatus.

Energization of the safe start relay 42 ends simulated presence of flame by the opening of switch 46. The closing of switch 45 places the Geiger tube 16 in controlling relationship to the discharge device 19 and places an operating voltage on the Geiger tube. It will be remembered that there is no flame present at the fuel burner unit at this time and therefore the Geiger tube 16 normally will not become energized.

However, the Geiger tube does have an inherent background count which is caused by ionizing events passing through the Geiger tube from random sources of radiation. In the event that Geiger tube 16 does become ionized by one of these random ionizing events, the quenching circuit including the discharge device 19 is now effective to quench the Geiger tube. Furthermore, the means by which the voltage applied to the control electrode 30 of discharge device 25 is integrated with respect to the voltage applied to the control electrode 29 insures that the flame relay 37 will not respond to this random ionizing event.

Energization of the safe start relay 42 likewise causes the switch 44 to assume a closed condition to thereby complete a holding energizing circuit for the winding 43 of this relay. This holding energizing circuit can be traced from the terminal 57 through the line switch 59, conductors 78, 79 and 83, winding 43, conductor 89, switch 44,

conductor 90, the lower portion of the primary winding 34, conductor 81, safety switch 52 and conductor 82 to the terminal'58. This above traced circuit insures that the winding 43 of the safe start relay will remain energized so long as voltage is continuously supplied to, the terminals 57 and 58. However, in the case of a power failure, the winding 43 will be de-e'nergi'zed as well as the other components of the control apparatus. Upon the re-establishment of voltage at the terminals 57 and 58,

it is necessary for the control apparatus to again go through a checking sequence where flame is simulated and the flame relay 37 is energized in response to this simulated flame, as above described.

As above described, when the safe start relay 42 is energized, switch 46 opens to thereby end the simulation of flame. The flame detector must now respond to the absence of flame at the burner unit 10 to 'de-energize the flame relay 37. When the flame detector does so respond, switch 40 of time relay 37 again opens to thereby break the initial energizing circuit of the safe start relay 42 and to close switch 41 which is in the initial energizing circuit of the main burner control relay 48. The appa- 7 ratus is now in the standby condition wherein controller 60 is in the condition to control ,the operation, of the fuel burner unit 10. i i

Assume now that the controller 60 closes, an energizing circuit is now completed for the winding 48 of the main burner control relay 47.. This energizingcircuit canbe traced from terminal 57 through line switch 59, controller 60, winding 48, conductor 91, switch 41 of flame relayf37, conductor 85, heater 53, conductors 84 and 89, switch 44 of safe start relay 42, conductor 90, the lower portion of transformer primary winding 34, conductor 81, safety switch 52, and conductor 82 to the terminal 58. It can be seen from this above tracedcircuit that the winding 48 of the, main burner 'control relay is not energized unless the flame relay 37 is in its de-energized condition indicating the absence of flame and the safe start relay 42 is inthe energized condition indicating that the electronic flame detector has'responded to the simulated presence of flame. and the subsequent absence of flame, thereby indicating that the flame detector is operating properly.

Energization of winding 48 of the main burner control relay causes the switch 49 of this relay to close. This completes a holding energizing circuit for the winding 48 of this relay and this circuit can be traced from the terminal 57 through line switch 59, controller 60, winding 48, switch 49, conductor 92, safety switch 52, and

conductor 82 to the terminal 58.

Energizing of relay 47 also causes the switchSl to open. It will be remembered that this switch is in the initial energizing circuit of the safe start relay 42 and therefore the opening of this switch maintains the initial energizing circuit of this relay open even though the flame relay 37 may subsequently be energized, as it will be when the flame is detected in the fuel burner unit. 10. Energizing of the main burner control relay. 47 also causes the switch 50 to close and thereby completes an energizing circuit for the ignition means 15 and the pilot valve 14 of the fuel burner unit .10. This energizing circuit can be traced from the power line terminal 57 through line switch 59, conductor-78, switch50, and conductor 93 to the ignition means 15 and the pilotvalve 14. The circuit is completed through conductors 94 and 95, safety switch 52 and conductor 82 to the power line terminal 58. Y

A flame is normally now established at the pilot burner 12 and this flame is sensed by the Geiger tube 16. As above described, Geiger tube 16 becomes ionized and causes discharge device 19 to become conductive. The conduction of discharge device 19 subsequently quenches the Geiger tube and as a result the Geiger tube' 16 and the discharge device 19 cycle'between states of conduction and non-conduction to produce a signal voltage on the control electrodes 29 and 30 of the discharge device 81 and 92, switch 49 of relay 47, conductor 91, switch 41 of relay 37, conductor 85, heater 53, conductors 84and 89, switch 44 of relay 42, and conductor 90 to the tap provided on the primary winding of transformer33 This above traced circuit provides for a pilot flame pr oving period which may extend anywhere from 15 to 90seconds' depending upon the construction of the safety switch 52. In the event that a pilot flame is not established within this time period, the bimetal 54 warps to the left and opens the switch 55 to thereby disconnect the. apparatus from .thepower line terminal 58. Normally however a flame is established within this period, to energize flame relay 37.

. Energization of flame relay .37 opens the switch pleted through switch 39, conductors 96 and; 95, safety switch 52, and conductor 82 to the power line terminal I The apparatusiof Figure l is now in its running condition wherein a flame is present at the burners 11 and 12 and the Geiger tube 16 continuously senses the flame. In the event that there is a subsequent flame failure, the Geiger tube senses the absence of flame and the flame relay 37 becomes de-energized. This causes switch39 to'open to thereby de-energize the main fuel valve 13 and furthermore closes the switchn41 to again energize the heater 53 of safety switch 52. After a given time period, for example 15 to seconds, the safety switch 52 is operative to open and to de-energize the entir apparatus. e

Normally however a flame continues at the burners 11 and 12 until the controller. 60 opens. Upon opening of this controller, themain-burner control relay 47 is de-energized to open the switch 50 and thereby deenergize all the components of the fuel burner unit 10. Furthermore, the switch 51 closes to complete a component checking circuit which once again energizes the heater 53 ofthe safety switch. This circuit can betraccd from the lower terminal of the primary winding 34 through conductor 88, switch 40, conductor 87, switch 51, conductors 86 and'85, heater 53, conductors 84 and 89, and switch 44 and conductor 90 to the tap of primary winding 34. This circuit checks the flame detector since the safety switch 52 is effective to'allow the electronicflame detector, including the Geiger tube 16, from 15 to 90 seconds to sense the absence of flameat the 42 functions to not only check the proper operation I of the flame detector but also prevents the application of operating voltage to the Geiger tube 16 until the quenching circuitincluding the discharge device 19 is in a condition where itis operative to quench the Geiger tube.

Figure 2 shows a modificationof a portionof Figure 1, the modification specifically consisting of modifying the manner in which the safe start relay 42 controls the inter-relationship of Geiger tube 16 and discharge device 19. In the modification of Figure 2 the safe start relay 42 is provided with a pair of normally open switches,

97 and 98, the switch 98 is identical in its function to the switch 44 of Figure l. Thecapacitor 71 and recti-z fler 70 again supply a source of biasingvoltage for the discharge device 19 and in the modification of Figure 2 the negative plate of capacitor 71 is connected to the control electrode 21 of discharge device 19 through a circuit which includes conductor. 99,: switch 97, conduc: tor 100 and resistor 101. 1

The anode. 18 ofGeiger tube 16 is connected by means i of conductor 102 to the anode 20 of dischargedevice 19 and also through resistor 67 to the upperpositive plate of capacitor 62, as is shown in Figure 1. The cathode, 17 of Geiger tube 16'is connected directly to the control electrode 21 of discharge device 19. Upon.

the safe start relay 42 being energized, cathode 17 of the Geiger tube is connected to a source of operating voltage on capacitor 62 through resistor :101, conductor 100, switch 97, conductor 99 and capacitor 71. The connection to the negative plate of capacitor 62 is completed by means of conductors 76 and 77 as shown in Figure 2'and by means of the network including resistors 68, 66, 65 and 32 as well as capacitor 31 and rectifier 64, as is shown in Figure 1. v

In this modification, with the safe start relay de-energized as shown, the control electrode 21 of discharge device 19 is floating since Geiger tube 161is in an unionized condition and in fact operating voltage is not applied to the Geiger tube. In this condition, discharge device 19 becomes conductive, much as'the discharge device 19 of Figure I became conductive due to the switch 46 of the safe start relay 42 being closed. This checks the flame detector, as above described with regard to Figure 1. Upon flame relay 37 being energized to cause energization of safe start relay 42, the switch 97 of Figure 2 is closed and the bias voltage is then applied to the discharge device 19. An operating voltage is also applied to the Geiger tube 16. The discharge device 19 therefore ceases conduction and the flame relay 37 is de-e'nergized to place the apparatus in the standby condition wherein the flame relay is de-energized, the safe start relay is energized, and operating voltage is applied to the Geiger tube.

Figure 3 shows a further modification of the present invention and here again the manner in which the safe start relay 42, the Geiger tube 16 and the discharge device 19 are inter-related has been modified. Furthermore, the discharge device 105 is a tetrode and the input circuit to the control electrodes 106 and 107 of this discharge device has also been modified from that shown in Figure 1.

Specifically, the input circuits to the discharge device 105 of Figure 3 both involve integration. Considering control electrode 106, this control electrode is connected to a resistor 108 which is connected in series with a parallel connected resistor 109 and capacitor 110. The control electrode 107 is connected to a resistor 111 which is connected in series with a parallel connected resistor 112 and capacitor 113. It is advisable in the case of the apparatus of Figure 3 to provide integration to each of the control electrodes. However, one of the signals is integrated more than the other. In other words, one of the signals is delayed or integrated with respect to the other. The discharge device 105 is rendered conductive only upon a coincidence of signals at the electrodes 106 and 107, in a similar manner to the functioning of the discharge device 25 in Figure 1. In this manner the apparatus of Figure 3 discriminates against the background count in the Geiger tube 16 in the same manner as the apparatus of Figure 1.

In the apparatus of Figure 3, resistor 114 is connected in circuit with the source of direct current voltage including rectifier 61 and capacitor 62. The voltage developed across this resistor 114 is of the polarity shown in Figure 3 and when the switch 104 of the safe start relay 42 is closed, this voltage biases the discharge device 19 substantially to cut off. This can be seen by tracing the circuit from the cathode 22 of this discharge device through resistor 114, conductor 115, switch 104, conductor 116, and resistor 117 to the control electrode 21 of discharge device 19. The anode 18 of the Geiger tube 16 is connected directly to the anode 20 of discharge device 19, as in Figure 2, and is further connected through the resistor 67 to the positive plate of the capacitor 62. The cathode 17 of Geiger tube 16 is connected to the negative terminal of this capacitor 62 through a circuit including resistor 117, conductor 116, switch 104, conductor 115, the input circuit of discharge device 105 and capacitor 118 to the lower plate of capacitor 62.

It can be seen that, as was the case in Figures 1 and 2, with the safe start re lay 42 de-energized operating voltage is not applied to the Geiger tube 16 and the presence of flame is simulated. The simulation of the presence of flame is accomplished in Figure 3 by breaking the bias connection from resistor 114 to the control electrode 210i discharge device 19. s

Discharge device 19 is then rendered conductive and the current flowing through this discharge device develops a signal voltage which is integrated and applied to' both of the electrodes 106 and 107 of the discharge device 105, thereby causing flame relay 37 to be energized In a the manner described in detail in connection with Figure 1, the energization of flame relay 37 causes the safe start relay 42 to be energized and this in turn causes the flame relay 37 to become de-energized. In this manner the operation of the electroniccomponents of the flame detector are checked, first to insure that the apparatus is capable of sensing a simulated presence of flame and then to insure that the apparatus senses the actual absence of flame at the fuel burner unit.

The controller 60 is then effective to cause energization of the main burner control relay 47 to thereby energize the components of the fuel burner unit 10, as previously described in connection with Figure 1.

It can be seen from the above description that I have provided an improved control apparatus having a safe start relay which not only checks proper operation of the flame detector but likewiseprevents application of operating voltages toa Geiger tube until the quenching circuit' is operative thereby providing an improved control apparatus which achievesrreliable and safe control of the fuel burner unit 10. Other modifications of the present invention will be apparent to those skilled in the artand it is intended that the scope of the present invention be limited solely by the scope of the appended claims.

I claim as my invention:

1. Condition sensing apparatus comprising; Geiger tube condition sensing means arranged to be subjected to an ionizing" condition, said Geiger tube being of the non-selfquenching type; a quenching circuit, circuit means connecting said Geiger tube in controlling relation to said quenching circuitto thereby cause'said quenching circuit to operate and to quench said Geiger tube upon said Geiger tube being subjected to the ionizing condition; a

source of voltage, a safe start relay having an actuator and a pair of normally open switches; circuit means con trolled by the first switch of said safe start relay in said open position to modify the connection of said Geiger tube to said quenching circuit such that an operating voltage is not supplied to said Geiger tube and an ionizing condition is simulated to thereby cause said quenching circuit to be operative, further means controlled by said quenching circuit when operative, means controlled by said last named means arranged to energize said safe start relay actuator upon said quenching circuit being rendered operative, and circuitmeans controlled by the second switch of said safe start relay arranged to main tain said safe start relay actuator continuously energized, said first switch of said safe start relay when in energized position being arranged to supply an energizing voltage to said Geiger tube.

2. A flame detector for use with a fuel burner unit comprising; a Geiger tube flame sensor arranged to be positioned to sense the flame at the fuel burner unit, said Geiger .tube' being of the non-selfquenching type; a quenching circuit including an electron discharge device, circuit means interconnecting said Geiger tube and said electron discharge device in mutual control of each other such that ionization of said Geiger tube causes said discharge device to be conductive and said discharge device when conductive causes said Geiger tube to be quenched; a normally de-energized safe start relay having an actu ator and a pair of switches, terminals adapted to be con;- nected to a source of operating voltage,-circuit means controlled by the first switch of said safe start relay arranged to modify the inter-connection of said Geiger tube and said quenching circuit toprevent the application of an operating voltage to said Geiger tube and to cause said discharge device to become conductive to thereby simulate the presence of flame upon the initial application of voltage to said terminals; means controlled by said discharge device when conductive, means controlled by said last-named means arranged to energize the actuator of said safe start relay upon said discharge device be coming conductive; circuit means controlled by the second switch of said safe start relay to maintain said safe start relay actuator energized, and further circuit means controlled by the first switch of said safe start relay to apply an operating voltage to said Geiger tube and to cause said discharge device to become non-conductive in the absence of flame at thefuel burner unit, said safe start relay thereby functioning to check the ability of said discharge device to sense the simulated presence of flame and also to prevent the application of operating voltage to said Geiger tube until said quenching circuit is operative to quench said Geiger tube.

3. Condition sensing apparatus comprising; Gelger tube condition sensing means of the non-selfquenching type, a quenching circuit including an electron discharge device, circuit means interconnecting said Geiger tube and said quenching circuit in mutual controlling relationship such that upon said Geiger tube experiencing an ionizing condition, said discharge device is rendered conductive to subsequently de-ionize said Geiger tube; a safe start relay having an actuator and switch means controlled thereby; a source of voltage, circuit means interconnecting said quenching circuit and said Geiger tube to said source of voltage; said circuit means being controlled by said switch means such that upon the apparatus bei ng initially connected to-the source of voltage, said relay actuator remains de-energized and said Geiger tube is rendered inoperative to sensean ionizing condition and an ionizing condition is simulated to cause energization of said discharge device; means controlled by said discharge device connected in circuit with the actuator of 'said relay to thereby cause energization of said actuator upon said discharge device responding to the simulated condition, and further circuit means controlled by said relay switch means to maintain said relay actuator energized once it is energized and render said Geiger tube operative while removingthesimulated; con dition. t a

4. Control apparatus comprising; Geiger tube condition sensing means of the non-selfquenching type, a quenching circuit, means interconnecting said Geiger tube and said quenching circuit in mutual controlling relationship such that upon said Geiger tubebeing subjected to an ionizing condition said quenching circuit is rendered effective to subsequently quench the Geiger tube; a source of voltage, a safe start relay having an actuator and switch means controlled thereby, circuit means controlled by said relay switch means connected in controlling relationship to said Geiger tube and said quenching circuit to prevent the application of operating voltage to said Geiger tube and to simulate the ionizing condition and thereby render said quenching circuit efiective so long as the actuator of said safe start relay remains de-energized; means controlled bysaid quenching circuit when effective arranged to connect the actuator of said safe start relay to said source of voltage to thereby energize said actuator; said relay switch means in energized condition removing the simulated ionizing condition to thereby cause said quenching circuit to become ineffective, and also applying operative voltage to said Geiger-tube; a main control relay having an actuator; and energizingcircuit means for the actuator of said main control relay :controlled by said relay switch means in energized condition and by said means controlled by said quenching circuit when said quenching circuit is ineffective.

5. Burner control apparatus for use with a fuel burner unitcomprising; Geiger tube flame sensing means arranged to beqsubjected toa flame at the fuel burner unit, said Geiger tube beingofithe non-selfquenching type; a quenching circuit, circuit means interconnecting said Geiger tube andsaid quenching circuit in mutually controlling relationship such that upon said Geiger tube being subjected to a flame, said quenching circuit is rendered operative to thereby quench said Geiger tube; a pair of voltage input terminals arranged to be con nected to a source of operating voltage, a safe start relay having an actuator and switch means controlledthereby, circuit means controlled by theswitch means of said safe start relay connected to said Geiger tube and said quenching circuit to disconnect said Geiger tube from said, input terminalsand ,to simulate the presence of flame so long as the actuator of said safe start relay 'is de-energized, said circuit means thereby causing said quenching circuit to become operative; means controlled by said quenching circuit, further circuit means controlled by said last named means and arranged to ener-,

gize the actuator of said safe start relay upon said quenching circuit becoming operative; circuit means controlled by the switch means of said safe start relay to maintain said safe start relay actuator energized, said safe startrelay switch means when said actuator is energized functioning to connect said Geiger tube to 1 said input terminals and thereby apply an operating, voltage to said Geiger tube and to also remove the simulation of flame whereby said Geiger tube senses the actual absence of flame at thefuel burner unit and said quenching circuit in turn becomes inoperative; a burner control relay having an actuator and switch means controlled thereby, energizing circuit means for the actuator of saidburner control relay arranged to, energize the actuator thereof upon said safe start relay actuator being energized and upon said quenching circuit assuming its inoperative condition; and further circuit means adapted to be connected to said fuel burner unit and controlled by the switch means of said burner 1 control relay.

6. Burnercontrol apparatus for use with a fuel burner unit comprising; a Geiger tube flame sensor oflthe nonselfquenching type arranged to be positioned toview the flame at the fuel burner, a quenching circuit including an electron discharge device, a source of voltage; circuit means interconnecting said Geiger tube, said discharge device and said source of voltage so that upon said Gelger tubebeing subjected to a flame said discharge device becomes conductive and said discharge device in the conducting state functions to quench said Geiger tube; a flame relay having switch means and an actuator which is connected to be controlled by said discharge device and to be energized upon said dischargedevice becoming conductive, a safe start relay having switch means and an actuator, circuit means controlled by the switch means of said safe start relay when in a de-energized position arranged to modify said first named circuit means to simulate aflarne and to disconnect said Geiger tube from said source of voltage to thereby render said Geiger tube insensitiveto a random ionizing event, said;las t .named circuit means thereby rendering said discharge device conductive to cause energization of said flame relay actuator; circuit means controlledby the switch means of saidflame relay arranged to energize the actu-j said energized position being arranged to apply an oper-I ating voltage to sald Geiger tube and to cease the simu-,

lation of flame to thereby cause said discharge device to become moperatlve-and said flame relay actuator to be de-energized; a main burner control relay having an actuator and switch means controlled thereby, energizing cir-; cult means for the actuator of said main burner control 13 relay including the switch means of said flame relay when de-energized, and the switch means of said safe start relay when energized, and further circuit means adapted to be connected to the fuel burner unit and controlled by the switch means of said main burner control relay, the apparatus thereby functioning to check the proper operation of said quenching circuit and to prevent the application of an operating voltage to said Geiger tube until said quenching circuit is operative.

7. Condition sensing apparatus comprising; Geiger tube condition sensing means of the non-selfquenching type, quenching means including an electron discharge device having an anode, a cathode and a control electrode, a source of operating voltage for said Geiger tube and said discharge device, a safe start relay having an actuating winding and a first normally closed switch and second and third normally open switches controlled thereby, circuit means connecting the anode and cathode of said discharge device to said source of operating voltage, biasing means connected to said cathode and said control electrode to bias said discharge device substantially to cutoff, circuit means controlled by said first normally closed switch of said safe start relay connecting said control electrode to said anode to thereby render said discharge device conductive so long as saidsafe start relay remains tie-energized, means controlled by said discharge device and arranged to energize the actuating winding of said safe start relay upon said discharge device becoming conductive, circuit means controlled by the second normally open switch of said safe start relay maintaining said safe start relay actuator energized, and further circuit means controlled by the third normally open switch of said safe start relay connecting said Geiger tube from the anode to the control electrode of said discharge device, said safe start relay thereby functioning to simulate the presence of a condition and to prevent the application of an operating voltage to said Geiger tube until said discharge device is in a conducting condition.

8. Condition sensing apparatus. comprising; Geiger tube condition sensing means of the non-selfquenching type, quenching means including an electron discharge device having an anode, a cathode, a control electrode, circuit means connecting the anode of said Geiger tube to the anode of said discharge device and the cathode of said Geiger tube to the control electrode of said discharge device, a source of operating voltage connected to the anode and cathode of said discharge device, biasing means for said discharge device, a safe start relay having an actuator and first and second normally open switches controlled thereby, circuit means connecting said biasing means from said cathode to said control electrode in series with the first of said normally open switches, said first normally open switch when in an open condition maintaining said biasing means disconnected from said discharge device and maintaining said Geiger tube disconnected from said source of operating voltage to thereby cause said discharge device to become conductive, means controlled by said discharge device when conductive arranged to energize the actuator of said safe start relay, said safe start relay thereby causing said first and second normally open switches to close, to apply said biasing potential to said control electrode and to apply said operating voltage to said Geiger tube, and further circuit means controlled by the second normally open switch of said safe start relay arranged to maintain the actuator thereof energized.

9. Condition sensing apparatus comprising; Geiger tube condition sensing means of a non-selfquenching type,

14 quenching means including an electron discharge device having an anode, a cathode and a control electrode, circuit means connecting the anode of said Geiger tube to a charge device to the junction of said first and second.

resistors to thereby apply an operating voltage to said discharge device, a safe start relay having an actuator and a pair of normally open switches, circuit means connecting said control electrode through a first of said normally open switches to the end therminal of said second resistor to thereby apply a bias to said discharge device to substantially cut oil? said discharge device and to further apply an operating voltage to said Geiger tube when said first switch is closed, said safe start relay in de-energized position functioning to prevent the application of operating voltage to said Geiger tube and to render said discharge device conductive, means controlled by said discharge device when conductive arranged to energize the actuator of said safe start relay, and further means controlled by the second normally open switch of said safe start relay to maintain the actuator thereof energized.

10. Burner control apparatus for use with a fuel burner unit comprising; Geiger tube flame sensing means of the non-selfquenching type, quenching means for said Geiger tube, circuit means interconnecting said Geiger tube and said quenching means in mutual controlling relationship such that ionization of said Geiger tube due to the presence of flame controls said quenching means to cause subsequent quenching of said Geiger tube; a flamerelay having an actuating winding and switch means controlled thereby, circuit means connecting said flame relay winding to be energized by said quenching means upon said quenching means being rendered operative to quench said Geiger tube; a safe start relay having an actuating winding and switch means controlled thereby, circuit means connecting said safe start relay switch means in controlling relationship to said quenching means and said Geiger tube to prevent the application of operating voltage to said Geiger tube and to simulate the presence of flame so long as said safe start relay winding is de-energized, energizing circuit means for the winding of said safe start relay controlled by the switch means of said flame relay to energize said safe start relay winding upon said flame relay winding being energized, holding energizing circuit means for said safe start relay winding controlled by the switch means of said safe start relay, a main burner control relay including a winding and switch means adapted to be connected to a fuel burner unit, initial energizing circuit means for said main control relay winding controlled by the switch means of said flame relay and the switch means of said state start relay to provide energization of said control relay winding upon said flame relay winding being de-energized and upon said safe start relay winding being energized, and holding circuit means for said main control relay winding controlled by the switch means of said main control relay.

References Cited in the file of this patent UNITED STATES PATENTS

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