US3813581A

US3813581A - Spark igniter for a plurality of gas burners

Info

Publication number: US3813581A
Application number: US00399368A
Authority: US
Inventors: W Hewitt
Original assignee: CAM STAT Inc
Current assignee: CAM STAT Inc
Priority date: 1973-09-21
Filing date: 1973-09-21
Publication date: 1974-05-28
Anticipated expiration: 1991-05-28

Abstract

A spark ignition system for a plurality of gas burners providing for operation of a plurality of spark ignition circuits from one a.c. source, with each of the ignition circuits having a voltage multiplier feeding a pulsing circuit which in turn provides ignition pulses to the ignition electrodes, with an isolation diode between the voltage multiplier and pulsing circuit of each ignition circuit.

Description

United States.Patent [191 7 Hewitt "1451 May 28,1974

[54] A IGNITER FOR APLURALITY 3,384,440 /19 3 Mayer .1 431/66 v GAS BURNERS 3,529,910 j 9/1970- Potts et al 431/27 J 3,561,900 2/1971 Walbridge 431/256 Inventor: William L yd L- C y, 1 $632,285 1/1972' Foster; 431/264 Calif. v 4 3,716,758 2/1973 Palazzetti 317/96 73 A -t" t v l sslgnee $322 g g L08 Primary Examiner-Velodymyr Y. Mayewsky v Attorney, Agent, or Firm-l-larris, Kern, Wallen & 22 F1led:- Sept. 21,1973 Tinsley [21] Appl. No.: 399,368 H [57] 7 ABSTRACT v [52] US. Cl 317/96, 315/183; 315/206, f park igni on system for a plurality of gas burners v 431/264 providing for operation of a plurality of spark ignition [51] Int. Cl. F23q 3/00 circuits from one as source, with each of h ignition [58] Field of Search 317/79, 96; 315/183, 206, circuits having avoltage multiplier feeding a pulsing 315/241;'431/27, 66, 256, 264, 266 circuit which in turn provides ignitionpulses to the igit 1 p I v 1 nition electrodes, with an isolation diode between the [561' References Qitedvoltage-multiplierand pulsing circuit of each ignition UNITED STATES PATENTS 1 i 3,045,148 7/1962 Mcllultyetal t..1....;.. 315/1811 SCluims, 1 Drawing Figure \1 n1 n1 1 i I 'l I I .gZf/t e .1 9 I 1; m 1.. 10 I I W vvv 1r I 5, #1- ,e1 2 2e 4e r 1 we? t g? ifs/z v, r\ a WM '1 r 'r M 1 1N3; {a V 11 43 4'1v N 1: =1 I t o 1 44% ii/if. 4a 7 1!. J

7 '1' L in I )v I I: 49 t age pulse across a pair of electrodes at the gas burner.

The pulsing circuit generates the pulses which produce sparks between the electrodes causing ignition of the gas at the burner. US. Pat. No. 3,349,284 shows an earlier form of pulsing circuit. US. Pat. No. 3,662,185 shows thepulsing circuit of 1.1.5. Pat. No. 3,377,125 energized by a voltage multiplier in the form of a voltage triplerl v It is preferable to operate the spark igniters from a low voltage ac source, typically by means of a step down transformer with the primary connected to the l l5 volt supply and with the secondary providinga 24 volt output. The 24 volt systems eliminate many wiring DESCRIPTION OF THE PREFERRE EMBODIMENT f Three

spark ignition circuits

10, 11, 12 are connected to power supply terminals 13, 1'4,which typically may be energized from the secondary winding of a transformer. The

circuits

10, 11, 12 are identical and each includes a voltage quadrupler l7 and a pulsing circuit 18, with the output of the pulsing circuit connected to the electrodes of a'spark gap igniter 19.

. The voltage quadrupler 17 includes a capacitor 21 connected between terminal 13 and junction 22, and

another capacitor 23 connected between terminal 13 and junction 24. A diode '25 is connected between

junctions

22 and 26, and another diode 27 is connected between junction 22 and terminal 14. A capacitor 28 is connected between the junction 26 and the terminal 14'. A series combination of a diode 30 and a resistor 31 is connectedbetween the junction 24 and the terminal 14, and another series combination of a diode 32 and a resistor 33 is connected between thejunction 24 and a junction 34 which may be connected to circuit ground. The diodes and are poled for conduction problems which must be handled using higher voltage systems. Also, it is often desirable to operate a plurality of thespark igniters from a'single source, i.'e., from a single step-down transformer. However problems are encountered when a plurality of the spark igniters are connected to a single ac supply. Common feedback paths are created between units and the resulting interaction causes the energygenerated in thevolt age multipliers to be continuously depleted. Accordingly, it is an object of the presentinvention to provide a new and improved spark ignition system particularly suited for operation with a plurality of gas burners from a single ac supply. A further object is to provide such a spark ignition system utilizing the conventional circuitry with a simple yet highlyeffective modificationwhich prevents energy stored in one. voltage multiplier; from being depleted by operation of related pulsing'circuits.

SUMMARY OF THE lNVENTlON" t The spark ignition system of the present invention incorporates a plurality of spark ignition circuits with the BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing illustrates a spark ignition system for three gas burners and incorporating the presently preferred embodiment of the invention.

in the same direction and the diodes 27' and 32 are poled for conduction .in the opposite direction. 1

The output of the quadrupler l7 is,developed.across a capacitor 40 at

junctions

41, 34 diode 42. I

In the pulsing circuit 18, the primary winding 44 of a high voltage step up, transformer 45 is connected in serieswith the anode and cathode ofa controlled recti fier 46 across the

junctions

41, 34. A resistor 47 is' connected in series with a capacitor 48 at junctions 49 across the

junctions

41, 34. A gas discharge device such as aneon lamp 52 is connected in series with

resistors

53, 54 across junctions 49 and34, with the control electrode of the controlled rectifier 46 connected to the junction 55 between

resistors

53, 54. j In operation, the capacitor 40 is charged from the voltagemultiplier, and the capacitor 48 is charged from the voltagemultiplier through the resistor 47. When the charge on thecapacitor 48 builds up to a predetermined value, the lamp'52conducts, discharging the cathrough another pacitor 48 through the

resistors

53, 54 and raising the junction 49 through the secondary 58 to circuit ground and prevents the capacitor 48 from charging to a value sufficient .to fire the lamp 52 while the flame is present. If the flame goes out for some reason, the pulsing circuit automatically produces the sparks at the igniter.

There is interaction between a plurality of the spark V igniters causing continuous depletion of energy from the voltage multipliers. This interaction is a result of the characteristics of the controlled rectifier (SCR) 46. The SCR is a bistable semiconductor which can be switched'from off to on and from on to off. When the voltage between the anode and cathode of the device is below the breakover point, current through the SCR is extremely small and the device is effectively an open switch. I

The SCR is turned on by the application of a current to'the gate or control electrode of the SCR. The gate current has the effect of lowering the SCR breakover point. Once breakover point is exceeded, the SCR switches to its on state, and will remain on with no further application of gate current, until the current from anode to cathode drops below holding current. When current between anode and cathode drops below holding current, the SCR reverts back to its high impedance offstate. 1

if a pluralityof spark igniters are connected to a single step-down transformer, energy stored in

capacitors

28 and 40 will transfer from one unit to another in such a way that a continuous holding current will be maintained on all SCRs. This causes them to remain on continuously. When these SCRs remain on continuously,

.

capacitors

28 and 40 which act as reservoirs when the SCRs are in the off state, will not be permitted to store energy. Diode 42 which permits current to flow in one direction only, will prevent the energy transfer from one spark igniter unit to another, and therefore permit any SCR to turnoff when the energy in capacitor 40 is depleted' i Typical values for the circuit may be:

1. In an electric spark i'ngition system for aplurality of gas burners, the combination of:

a pair of power supply terminals for connection to an ac. power source; and a plurality of spark ignition circuits, each comprising:

a voltage multiplier having input terminals connected to said power supply terminals and having multiplier output'terminals, I

a pulsing circuit having input terminals for connection to a voltage source and providing a pulse output to ignition electrodes of a gas burner, and

electriccircuit means connecting said pulsing unit input terminals to said multiplier output terminals with a unidirectional conducting device in circuit between one multiplier output terminal and the corresponding pulsing circuit input terminal.

2; A system as defined in claim 1 wherein each of said voltage multipliers is a voltage quadrupler.

3. A system as defined in claim 1 including three of said spark ignition circuits. r

4. A system as defined in claim 3 wherein each of said voltage multipliers is a voltage quadrupler.

5. A'system as'defined in claim [wherein each of said voltage multipliers includes:

a first capacitor and a first diode connected in series 'at a first junction between one of said power supply terminals and said one multiplier output terminal,

a second capacitor connected between said one multiplier output terminal and the other of said power supply terminals, a

a second diode connected between said first junction and said other power supply terminal,

a third capacitor and a third diode connected in series at a second junction between said one power supply terminal and the other of said multiplier output terminals, and

a fourthdiode connected between said second junction and said other power supply terminal. with said first and fourth diodes and said unidirectional conducting device poled for conduction in the same direction and with said second and third diodes poled for conduction in the opposite direction.

Claims

1. In an electric spark ingition system for a plurality of gas burners, the combination of: a pair of power supply terminals for connection to an a.c. power source; and a plurality of spark ignition circuits, each comprising: a voltage multiplier having input terminals connected to said power supply terminals and having multiplier output terminals, a pulsing circuit having input terminals for connection to a voltage source and providing a pulse output to ignition electrodes of a gas burner, and electric circuit means connecting said pulsing unit input terminals to said multiplier output terminals with a unidirectional conducting device in circuit between one multiplier output terminal and the corresponding pulsing circuit input terminal.

2. A system as defined in claim 1 wherein each of said voltage multipliers is a voltage quadrupler.

3. A system as defined in claim 1 including three of said spark ignition circuits.

5. A system as defined in claim 1 wherein each of said voltage multipliers includes: a first capacitor and a first diode connected in series at a first junction between one of said power supply terminals and said one multiplier output terminal, a second capacitor connected between said one multiplier output terminal and the other of said power supply terminals, a second diode connected between said first junction and said other power supply terminal, a third capacitor and a third diode connected in series at a second junction between said one power supply terminal and the other of said multiplier output terminals, and a fourth diode connected between said second junction and said other power supply terminal, with said first and fourth diodes and said unidirectional conducting device poled for conduction in the same direction and with said second and third diodes poled for conduction in the opposite direction.