US3662185A

US3662185A - Spark generator and components therefor

Info

Publication number: US3662185A
Authority: US
Inventors: Said Sapir
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1970-10-01
Filing date: 1970-10-01
Publication date: 1972-05-09
Anticipated expiration: 1989-05-09
Also published as: FR2109942A5; DE2148429A1

Abstract

A spark igniter for gas fired devices wherein the isolated capacitor of a diode-capacitor voltage tripler is used to store electrical charge for firing the igniter. A timer is used to fire the igniter, whereby peak line current is kept very small. A special circuit is employed to disable the timer when the gas is lit.

Description

D United States Patent 7 [151 3,662,185 Sapir [4 1 May 9, 19 72 [54] SPARK GENERATOR AND [56] References Cited COMPONENTS THEREFOR UNITED STATES PATENTS lnvenwfl Said p Wesflake Village, Calif- 3,441,356 4/1969 Walbridge .43 1/66 l h [73] Asslgnee' ggs fi ggz zfl sgrg v Te egrap Primary Examiner-Herman J. Hohauser p0 Au0rne vC. Cornell Remsen, Jr., Walter J. Baum, Paul W. [22] Filed: Oct. 1, 1970 Hemminger, Charles L. Johnson, Jr. and Thomas E. Kristof- 21 Appl. No.: 77,070

[57] ABSTRACT [52] U.S.Cl ..307/l06, 321/ l5,34037l//l6666, A Spark igniter for g fired devices erein the isolated 51 I t I I "03k 3/00 capacitor of a diode-capacitor voltage tripler is used to store S l 17 1 8 electrical charge for firing the igniter. A timer is used to fire 307/l 19, 106, I08; 431/61, 62, 63, 64, 65, 66 X the igniter, whereby peak line current is kept very small. A special circuit is employed to disable the timer when the gas is lit.

6 Claims, 2 Drawing Figures PATENTEDMM 9 1972 SHEEI 1 0F 2 INVENTOR Y 59/0 SAP/R HTTORNE V F'A'TENTEBMM 91972 SHEET 2 [1F 2 INVENTOR.

SAID SAP/R BY 3 I ATTORNEY l SPARK GENERATOR AND COMPONENTS THEREFOR BACKGROUND OF THE INVENTION This invention relates to sources of potential, and more particularly, to a spark generator and a voltage tripler therefor.

Although the system and voltage tripler of the present invention and certain circuit portions thereof may be used in arts wholly unrelated to fuel ignition, the invention has been found to be especially useful in automatically igniting natural gas emanating from a pilot burner used in a device such as a furnace or water heater in rooftop or other installations in which the device is not easily accessible. Due to the wide range of application of the invention, its use is not limited to either those described hereinbefore or hereinafter.

In the. past, spark generators for fuel ignition have frequently caused heavy current surges in the line. Such devices are disclosed in U. S. Pat. Nos. 3,349,284 and 3,377,125. Brief but frequent and heavy current demands can cause the line voltage to drop, to increase the average power consumption and to increase line losses. All of these results are undesirable.

The cost and size of prior art spark generators have also been large.

SUMMARY OF THE INVENTION In accordance with the device of the present invention, the

above-described and other disadvantages of the prior art are capacitor. The isolation of this capacitor reduces any current drain on the source which might otherwise occur when the capacitor is discharged during arcing.

Another feature of the invention resides in the use of two auxiliary capacitors smaller than the storage capacitor. The auxiliary capacitors thus are charged by line current at a low rate and one dumps its charge into the storage capacitor a little at a time. Peak line current is thus kept small. A series resistor reduces charging current and peak line current at the source frequency.

Another feature of the invention is the use of a timer to fire the igniter at a frequency less than the line frequency. Peak line'current and average power are thus both reduced. The lower timerfrequency permits the charging of the storage capacitor to a conveniently higher voltage with a low peak line current.

It is a feature of the invention that all three capacitors are combined into a voltage tripler to substantially reduce the size and cost of the igniter transformer. Note that the size and cost of the transformer is proportional to its turns or turns ratio, and the latter number is very large because an open circuit voltage of about 20 KV must be employed to reliably produce an arc across a representative 3/ 16-inch gap. The spark, however, does appear at a lower voltage since the open circuit voltage is measured with the transformer secondary leads much further apart than three-sixteenths inch. A large secondary voltage is required so that the igniter will have a small output rise time, will not be sensitive to normal gap tolerances, and can break down any deposits that may accumulate on the pilot or on the electrode.

The storage capacitor thus has a dual function. It stores electrical-charge for spark ignition. It also actually increaes 1 the output voltage of the multiplier from 2E to 3E.

A further feature of the invention resides in the fact that the capacitors of the tripler actually reduce the peak line current while they effect the voltage boost advantage of the tripler at the same time.

It is an advantage of the invention that the supply voltage may come from a transformer. Prior art devices would not operate in this case because of the damping effect of transformer inductance on rapid changes in current. The present invention is operative in such a case because the storage capacitor is isolated from the source and does not discharge therethrough.

It is a feature of the invention that peak line current is reduced. Note that instantaneous power is proportional to iR where i is current and R is resistance. The control of peak cur rent is thus exceptionally important because instantaneous power is not merely a linear function of current, but a squared function thereof.

Another advantage of reduced peak line current is concurrent reduction in radio frequency interference (RFI) and television interference (TVI). Conductive RF] and TW are reduced because the storage capacitor and its discharge igniter circuit are isolated from the line. The high frequencies generated on discharge and ignition are thus not conductively coupled to the line.

The above-described and other advantages of the invention will be better understood from the following description when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 in the drawing is a schematic diagram of a spark igniter for a gas fired device.

FIG. 2 is a schematic diagram of an alternative embodiment of a voltage tripler constructed in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing the igniter of the present invention is indicated at 10 having input terminals 11 and 12 for connection of an ac supply.

Various points in the circuit include junctions. For example, junctions are indicated at 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 and 26. An input lead wire 27 is connected from terminal 11 to junction 13. A capacitor C1 is connected between junctions l3 and 14. A diode D1 is connected between junctions 14 and 18. A diode D2 is connected between

junctions

14 and 15. A capacitor C2 is connected between junctions 15 and 18. A lead wire 28 is connected between terminal, 12 and junction 18. A capacitor C3 is connected between junctions 16 and 19.

A series circuit 29 is connected between junctions l3 and 19. Series circuit 29 includes a resistor R1 connected from junction 19 to the anode 30 of diode D3. The cathode 31 of diode D3 is connected to junction 13.

Capacitor C3 is connected between junctions 16 and 19.

A pilot burner is indicated at 32. Pilot burner 32 may burn, for example, natural gas. Pilot burner 32 includes a conduit 33 for the natural gas having an opening 34 through which the gas emanates. The gas thus burns above opening 34.

Burner 32 also includes a shield 35 having a horizontally projecting tip 36. Shield 35 may be employed as a wind guard for the frame. At the same time, projection 36 is employed as a spark electrode.

As described, conduit 33 and guard 35 both may be conductive and may be conductively fixed together. Guard 35 may be grounded in any desired manner, for example, at 26. Normally, guard 35 would be grounded simply by the way in which it is conventionally fixed in position. That is, in most cases, it will not be necessary to take any additional steps to ground guard 35.

A lead 37 connects junctions l5 and 16. A lead 38 connects junctions l6 and 17. A resistor R2 is connected between junctions 17 and 20, A lead 39 is connected between junctions 20 and 21. A conventional neon lamp N1 is connected between junctions 21 and 22. A capacitor C4 is connected between junctions 21 and 22. A resistor R4 is connected between junctions 23 and 24. A lead 40 connects

junctions

19 and 22. Lead 41 connects

junctions

22 and 24.

A transformer is indicated at T1. Transformer T1 has a primary winding 42 and a secondary winding 43. A second series circuit is indicated at 44 connected between junctions l7 and 24. Series circuit 44 includes transformer primary 42 and a silicon-controlled rectifier (SCR), wherein the primary 42 is connected from junction 17 to the anode 45 of SCR CR1, the cathode 46 of the SCR CR1 being connected to junction 24. SCR CR1 has a gate 47 connected to junction 23 by a lead 48.

One side of secondary 43 is connected to junction 21 by a lead 49. The other side of secondary 43 is connected to the other spark electrode 50 at junction 25 over a lead 51. insulation, which is broken away, is indicated at 52.

Spark electrode 50 may be supported in a fixed position, as shown, by any conventional means 53.

Each component part of the igniter may have the following values:

Capacitor C1 .1 microfarad, 250 volts Capacitor C2 .1 microfarad, 250 volts Capacitor C3 2.2 microfarads, 250 volts Capacitor C4 .1 microfarad, 200 volts Diode D4 IN 914 Diode D2 IN 914 Diode D3 IN 9l4 SCR CR1 IR l06A Neon Lamp N1 Type A0 79 Resistor R1 L000 ohms Resistor R2 33 megohms Resistor R4 1,000 ohms AC Supply 24 volts, 50/60 hertz From the foregoing, it will be appreciated that the capacitance of capacitor C1 is equal to that of capacitor C2. Similarly, the capacitance of capacitor C4 is equal to that of capacitor C1. [t is not necessary to use these relative values for capacitors C1, C2 and C4. However, values close to these relative values are preferred. In particular, capacitors Cl and C2 each have to capacitance substantially .less than capacitor C3. it is the capacitor C3 which discharges through transformer primary 42 to create the are between spark electrodes 36-and 50.

If terminal 12 first goes positive and there is no charge on capacitor C2, capacitor C2 will not charge in a direction opposite to that shown because the electrodes of capacitor C2 are clamped together by diodes D1 and D2. Only capacitors Cl and C3 would charge with the polarities shown.

The transient response of capacitors C1 and C2 to charge from zero charge if terminal 11 first goes positive is for capacitor C3 not to charge, for capacitor C2 to charge with the polarity shown, and for capacitor C1 to charge with the opposite polarity. However, on the immediately succeeding half cycle of the supply voltage, capacitor C1 would discharge extremely rapidly into a low supply impedance and begin to charge with the polarity shown for the following reasons.

The normal charging operation of capacitor C3 begins when terminal 12 first becomes positive with respect to terminal 11. In this case, capacitor C1 charges rapidly through the source impedance to the peak potential reached between terminals 11 and 12 through diode D1. When the ac. supply voltage across terminals 11 and 12 reverses the terminal 11 becomes positive with respect to terminal 12, capacitor C1 discharges into capacitor C2 through diode D2. Capacitor C3 receives additional charging while terminal 11 is positive as capacitors discharge thereinto. Charging thus continues until the peak dc. voltage across capacitor C2 is approximately equal to twice the peak of the supply voltage. Capacitors C1 and C2 with diodes D1 and D2 form an entirely conventional voltage doubler should circuit 29 be disconnected from junctions 13 and 19, and lead 37 be disconnected from junctions 15 and 16.

Although the charging of capacitor C2 has been described as being independent of capacitor C3, it is, in fact, not independent. For example, each time terminal 12 becomes positive with respect to terminal 11, capacitor C3 is directly placed across the line as follows. The circuit from terminal 12 is made through lead 28, capacitor C2, capacitor C3, series circuit 29, and lead 27 to terminal 11. Thus, when terminal 12 is positive with respect to terminal 11, capacitor C2, if it is charged with the polarity shown, will discharge into capacitor C3. Since the voltage at terminal 12 is at E peak, and the voltage across capacitor C2 is actually 2E, the peak d.c. voltage reached across capacitor C3 is thus 3E.

The resistor R1 is optional. Thus anode 30 of diode D3 may be connected directly to junction 19. For this reason, the said voltage doubler combined with capacitor C3 and diode D3 is a voltage tripler. Resistor R1 merely limits the charging current of capacitor C3 and therefore reduces the line current, but resistor R1 is primarily employed to limit the discharge of capacitor C3 when it is charged with the reverse polarity. It is so charged after spark ignition because C3 with transformer T1 acts as a tuned circuit which rings.

In accordance with the present invention, placement of spark electrodes 36 and 50 in a position such that the resistance therebetween is substantially reduced when the gas is ignited makes it possible to prevent spark ignition in that case.

When the gas is not ignited, the resistance between junction 20 and current is extremely high. Capacitor C4 then charges through resistor R2. The potential of junction 21 thus rises above ground as capacitor C4 charges. When the potential of junction 21 is sufficiently high, neon lamp N1 fires. When neon lamp N1 fires, SCR CR1 is gated on, and capacitor C3 discharges. The discharge path of capacitor C3 is through lead 38, series circuit 44, lead 41, and lead 40 to ground. The discharge of capacitor C3 causes an arc to be produced between electrodes 36 and 50. Electrode 36 is maintained at or is at ground potential. Note junction 26 is grounded. Current to sustain the arc which passes through electrode 50 and through secondary 43 to ground also flows through lead 39 and through capacitor C4. This is true because the secondary current is somewhat triangular as a function of time, ie a spike. The peak current may be 1,200 milliamperes and may exist for about 1 microsecond. Thus a Fourier analysis of the spike would reveal a fundamental of about 1 megahertz. At 1 megahertz, the impedance of capacitor C4 is less than 2 ohms.

When the gas is ignited, the resistance between spark electrodes 36 and 50 may be reduced to about 30 megohms. This 30-megohm resistance in combination with the 33-megohm resistance of resistor R2 acts as a voltage divider between junction 17 and ground. The dc. resistance of secondary 43 is negligible in comparison to the 33-megohm resistance of resistor R2. Thus, the potential of junctions 20 and 21 are dept sufficiently low so that neon lamp N1 cannot fire.

Resistors are V2 W, 10%.

SUMMARY OF OPERATION The voltage triplet develops a dc. voltage across capacitor C3 with the polarity indicated, which is about three times the peak voltage of the supply. Capacitor C3 is charged a little bit at a time by first charging capacitor C1, then charging capacitor C2, and finally charging capacitor C3.

As capacitor C3 charges, the potential of junction 17 rises. As the potential of junction 17 rises, capacitor C4 charges at a greater rate, but at a rate which is also a function of the resistance of resistor R2 and its own capacitance Capacitor C3 charges slowly. The charging potential of capacitor at junction 17 thus rises slowly. The rise in the potential of junction 20 is even slower because it is inherent in the operation of capacitor that it cannot change its voltage instantaneously. The firing frequency of the SCR CR1 thus is reduced substantially below the ac. supply frequency by the charging of capacitor C4. Note also that the charging rate of capacitor C4 is determined by the magnitude of the resistance of resistor R2 which is very large, Le. 33 megohms, For the foregoing reasons, neon lamp N1 may not fire except at 3- second intervals when the supply frequency is 60 hertz.

When the potential at junction 21 rises sufficiently, neon lamp N1 fires discharging capacitor C4 through resistor R4 and raising the potential of gate 47 until SCR CR1 fires.

When SCR CR1 fires, capacitor C3 discharges through transformer primary 42, and the secondary output voltage causes an arc to be sustained for a brief time between spark electrodes 36 and 50, the ground return for transformer secondary 43 over lead 49 being through capacitor C4.

Once the gas is ignited, the resistance between electrodes 36 and 50 reduces because the gas therebetween ionizes and creates a lower resistance path. This, therefore, keeps the potential of junction 21 below the firing potential of neon lamp N1.

In accordance with the foregoing, it will be appreciated that line peak current is kept small because capacitors C1 and C2 together pump in a small charge each cycle of the line frequency into capacitor C3. Further, note that the discharge path capacitor C3 is effectively isolated from the a.c. supply. That is, discharge path extends through lead 36, circuit 44, lead 41, and lead 40 to ground and is wholly disconnected from the a.c. supply. Note that the path just described does not include the a.c. supply.

The invention has a timer which includes, for example, capacitor C4. Due to the fact that the firing rate is substantially smaller than the line frequency, additional time is provided to charge capacitor C3 to a higher voltage with a low peak line current as well as a low average current, i.e. low power. The power consumption is directly proportional to are frequency.

Note will be taken that the voltage tripler of the invention provides duel advantages. For example, the increase in line voltage makes it possible to use a smaller capacitor and to use a transformer of a substantially smaller size and of a substantially lower cost. For example, assume that the transformer turns ratio is to 2,000. In order to triple the output voltage, the transformer turns ratio would have to be increased to 10 to 6,000. Moreover, a nominal open circuit voltage of 20,000 volts must be created between electrodes 36 and 50 to create an are over a distance of about three-sixteenths inch.

Note that capacitor C3 performs a dual function. It performs a voltage tripling function in the tripler, and it performs a capacitor discharge function in the igniter.

The combination of resistor R2 and capacitor C4 makes an extremely inexpensive timer. Moreover, nothing need be added to bias junction toward ground to disable the timer except the connections of the electrodes 36 and 50 and their placement in the flame.

Should a transformer be connected to terminals 11 and 12, the embodiment of the present invention will operate without difficulty. This is true because the discharge path of capacitor C3 is not through the a.c. supply. Such a transformer cannot be used in the device disclosed in the aforementioned patent. This is true because the capacitor discharge in the device of said patent is through the a.c. supply. In such a case, an input transformer would present an extremely high impedance to the are generating current and would prevent the are from being produced at any time.

It is a special feature of the invention that peak current in the line is reduced because instantaneous power is directly proportional to the square of current. A reduction in peak current thus provides a marked reduction in power.

As stated previously, the discharge of capacitor C3 through primary 42 and not through a.c. supply provides the reduction of RF] and TVI peak into the line. Note will be taken that there are several features of the invention disclosed herein that may be used in this and other arts. Each feature of the invention may be used in any combination with any of the other features or by itself.

As stated previously, resistor R1 may be omitted. The voltage tripler may be used by itself. The timer may be used by itself. If no automatic timer shutdown is desired or required, lead 49 may be disconnected from junction 20 and connected directly to ground. The location of spark electrodes 36 and 50 is thus less important.

Any voltage breakdown device may be used for neon lamp N. If, for example, a trigger diode replaced neon lamp N1, an additional resistor might be connected between

junctions

20 and 22.

THE ALTERNATIVE EMBODIMENT OF FIG. 2

An alternative embodiment of the voltage tripler of the present invention is indicated at 54 in FIG. 2.

As before, tripler 54 has

various junctions

55, 56, 57, 58, 59, 60, 61 and 62. Tripler 54 has input leads 63 and 64, and output leads 65 and 66.

Tripler 54 may replace the voltage tripler of FIG. 1. For example, leads 38 and 40 may be disconnected from junctions l7 and 22, respectively, and leads 65 and 66 connected thereto, respectively.

In the circuit of FIG. 2, three terminals 67, 68 and 69 are provided. A resistor 70 is connected from terminal 67 to junction 55. Terminal 68 is also connected to junction 55. Terminal 69 is connected to junction 56. A resistor 71 is connected between

junctions

55 and 56.

If leads 63 and 64 are broken so that they do not touch

junctions

55 and 56, only the right-hand portion of the circuit comprises the tripler 54, all of the structure on the left side thereof being simply input apparatus which may or may not be used, as desired. Specifically, resistors 70 and 71 form a voltage divider so that alternatively l20 volts may be applied between

terminals

67 and 69, or 24 volts may be applied between terminals 68 and 69.

A resistor 72 is connected between junctions 55 and 57. A diode 73 is connected between junctions 57 and 58. A diode 74 is connected between

junctions

58 and 59. A capacitor 75 is connected between junctions 57 and 59. A diode 76 is connected between junctions 59 and 61. A capacitor 77 is connected between junctions 61 and 62, junction 62 being grounded in the manner that junction 19 in FIG. 1 is also grounded. A lead wire 78 is connected between junctions 60 v and 62. A capacitor 79 is connected between

junctions

58 and 60.

Tripler 54 may appear to be strikingly different from the tripler shown in FIG. 1, however, tripler 54 is in fact very similar to the tripler in FIG. 1, and the operation of the tripler 54 is substantially identical to that of the tripler shown in FIG. 1. For example, all of the common circuit elements may have identical values. What is meant by common" are those analogous circuit elements. For example, capacitor 79 may be identical to capacitor C1 in size and in all other respects. That is, the capacitance of capacitor 79 may be identical to the capacitance of capacitor C1. Similarly, capacitor 75 may be identical to capacitor C2 and capacitor 77 may be identical to capacitor C3.

One change in tripler 54, it will be noted, is that lead 27 of FIG. 1 has been replaced with lead 64 and placed on the bottom of the figure and grounded at junction 62. However, with this and two other exceptions, the tripler of FIG. 2 is identical to the tripler of FIG. I.

One of the two other exceptions is that resistor 72 may be identical to resistor R] but is located in a different position. Diode 76 may also be identical to diode D3, but it too is located in a different position. Thus, the location of diode 76 is the other one of the said two exceptions.

When the word identicaP is used herein, this word is hereby defined for such use as meaning at least that the resistance of resistor 72 is identical to the resistance of resistor R1, and that the capacitances of

capacitors

79, 75 and 77 are identical to the capacitance of capacitors C1, C2 and C3, respectively.

The tripler of FIG. 2 is advantageous in one respect over the tripler in FIG. 1 in that by placing resistor 72 and diode 76 in the ungrounded side, a short existing between leads 63 and 64 or any extension thereof to the left, as shown in FIG. 2, will not cause resistor 72 and diode 76 to burn out.

The phrase means to supply an alternating input voltage and the phrase a circuit to supply an alternating input voltage" are hereby defined for use herein and in the claims to mean an a.c. source of potential or only input lead wires without an a.c. source of potential connected thereto or otherwise.

For use herein, the symbol T is hereby defined as the period of time which is required to store a predetermined maximum amount of energy in capacitor C3 or in capacitor 77. The maximum amount of energy stored may be equal to or less than 1% CH where C is the capacitance of capacitor C3 or the capacitance of capacitor 77, and E is the maximum voltage across capacitor C3 or the maximum voltage across capacitor 77 when the lamp N1 is never fired.

The maximum amount of energy'stored will depend upon the resistance-capacitance time constant of resistor R2 and capacitor C4.

For use herein, the symbol T is hereby defined as T= l/f, where f is the frequency of the input voltage.

According to the foregoing, it is one outstanding advantage of the present invention that capacitors C3 and 77 charge slowly because they are charged by the smaller capacitors C1, C2, 75 and 79. This causes a low even current drain on the source of the potential. This is made possible because the resistor R2 and the capacitor C4 provide a timing mechanism to fire the SCR CR1 at a frequency force less than line frequenm"- Restated, capacitors C3 and 77 charge slowly to reduce the line current load, and resistor R2 and capacitor C4 act to allow the slow charging. Thus, although T is larger than T, the firing frequency produced by resistor R2 and capacitor C4 is always less than the line frequency and accommodates the lower charging period for capacitors C3 and 77.

It may be of some help in understanding this invention to know of some prior art which is different from this invention. For example, voltage triplers broadly, not of the kind of the present invention, are well-known in the art. However, such voltage triplers have never been combined with a spark igniter circuit. One such voltage tripler may be described in connection with FIG. 1 herein. Thus, assuming all the structure to the right of junctions 19 is removed in FIG. 1, the prior art voltage tripler would be arrived at by disconnecting the upper electrode of capacitor C3 from junction 16, and then connecting it to junction 18, and replacing resistor R1 with a conductive lead. In addition to the U. S. patents previously cited, U. 8. Pat. Nos. 2,799,809; 3,045,l48; and 3,004,184 may be considered of interest even though different from the circuits and other structures disclosed herein.

Either embodiment of the voltage tripler of the present invention or any other embodiment thereof may be employed in a voltage quadrupler or other voltage multiplier for producing a dc. output voltage larger than three times the peak input voltage.

What is claimed is:

l. A voltage multiplier comprising: first and second input leads; a first capacitor having one electrode connected to said first input lead; first and second diodes, each of said first and second diodes having an anode and a cathode, the anode of said first diode being connected from said second input lead, the other electrode of said first capacitor being connected to the cathode of said first diode, the anode of said second diode being connected to said first diode cathode; a second capacitor connected from said first diode anode to said second diode cathode; and a series circuit connected from said second diode cathode to said first input lead, said series circuit including a third diode and a third capacitor connected in series, said diode being poled to be conductive in a direction toward said first input lead.

2. The invention as defined in claim 1, wherein said third diode has an anode and a cathode, said third diode anode being connected to one electrode of said third capacitor, said third diode cathode being connected to said first input lead, the other electrode of said third capacitor being connected to said second diode cathode.

3. The invention as defined in claim I, wherein said third diode has an anode and a cathode, said third diode anode being connected to said second diode cathode, said third capacitor having one electrode connected to said third diode cathode, and another electrode connected to said first lead.

4. A pulse generator comprising: first means to supply an alternating input voltage; second means connected from said first means, said second means including an electrical energy storage device, said second means being actuable to store a predetermined maximum amount of energy in said device but only at a rate such that said maximum amount is stored over a period of time, T,,, such that T, is larger than T, where T= l/f, and f is the frequency of said input voltage; third means connected to said device, said third means being actuable to discharge said device rapidly and repeatedly over time intervals small in comparison to T, said third means being actuable to discharge said device at a frequency which is less than f, said third means including a spark igniter for the pilot light of a gas-fired appliance; said second means being a voltage multiplier, said device being a first capacitor, said third means being connected in parallel with said capacitor, said multiplier including a second capacitor actuable charge said first capacitor only on alternate half cycles of said input voltage, said second capacitor being connected to be recharged periodically, said first capacitor having a capacitance large in comparison to that of said second capacitor.

5. A pulse generator comprising: first means to supply an alternating input voltage; second means connected from said first means, said second means including an electrical energy storage device, said second means being actuable to store a predetermined maximum amount of energy in said device but only at a rate such that said maximum amount is stored over a period of time, T,,, such that T is larger than T, where T= l/f, and f is the frequency of said input voltage; third means connected to said device, said third means being actuable to discharge said device rapidly and repeatedly over time internals small in comparison to T, said third means being actuable to discharge said device at a frequency which is less than f; said first means including first and second input leads, said second means including a first resistor, first and second capacitors and first, second and third diodes, each of said diodes having an anode and a cathode, said electrical energy storage device being a third capacitor, said first resistor being connected from said second input lead to said first diode anode, said second diode anode being connected to said first diode cathode, said third diode and anode being connected to said second diode cathode, said third capacitor being connected from said third diode cathode to said first input lead, said second capacitor being connected from said first diode anode to said third diode anode, said first capacitor being connected from said first input lead to said second diode anode, said third means including a transformer having a primary winding and a secondary winding, a silicon-controlled rectifier having an anode, a cathode and a gate, said primary winding having one end connected to said third diode cathode, and its other end connected to said silicon-controlled rectifier anode, said silicon-controlled rectifier cathode being connected to said first input lead, a second resistor having one end connected to said third diode cathode, a fourth capacitor having one electrode connected to the other end of said second resistor, and its other electrode connected to said first input lead, a neon lamp connected from said other end of said second resistor to said gate, a third resistor connected from said gate to said first input lead, a pilot burner having an orifice to allow the emission of a combustible gas, two spaced spark electrodes located in a position relative to said orifice to lie approximately within any flame created by the combustion of gas emanating from said orifice, said transformer secondary winding having one end connected to one of said spark electrodes, and its other end connected to said other end of said second resistor, the other spark electrode being connected to said first input lead, said third capacitor having a capacitance in excess of twenty times that of said first capacitor, said third capacitor having a capacitance in excess of twenty times that of said second capacitor.

6. A pulse generator comprising: first means to supply an alternating input voltage; second means connected from said first means, said second means including an electrical energy storage device, said second means being actuable to store a predetermined maximum amount of energy in said device but being a first capacitor, said third means being connected in parallel with said capacitor, said multiplier including a second capacitor actuable charge said first capacitor only on alternate half cycles of said input voltage, said second capacitor being connected to be recharged periodically, said first capacitor having a capacitance large in comparison to that of said second capacitor.

Claims

1. A voltage multiplier comprising: first and second input leads; a first capacitor having one electrode connected to said first input lead; first and second diodes, each of said first and second diodes having an anode and a cathode, the anode of said first diode being connected from said second input lead, the other electrode of said first capacitor being connected to the cathode of said first diode, the anode of said second diode being connected to said first diode cathode; a second capacitor connected from said first diode anode to said second diode cathode; and a series circuit connected from said second diode cathode to said first input lead, said series circuit including a third diode and a third capacitor connected in series, said diode being poled to be conductive in a direction toward said first input lead.

3. The invention as defined in claim 1, wherein said third diode has an anode and a cathode, said third diode anode being connected to said second diode cathode, said third capacitor having one electrode connected to said third diode cathode, and another electrode connected to said first lead.

4. A pulse generator comprising: first means to supply an alternating input voltage; second means connected from said first means, said second means including an electrical energy storage device, said second means being actuable to store a predetermined maximum amount of energy in said device but only at a rate such that said maximum amount is stored over a period of time, To, such that To is larger than T, where T 1/f, and f is the frequency of said input voltage; third means connected to said device, said third means being actuable to discharge said device rapidly and repeatedly over time intervals small in comparison to T, said third means being actuable to discharge said device at a frequency which is less than f, said third means including a spark igniter for the pilot light of a gas-fired appliance; said second means being a voltage multiplier, said device being a first capacitor, said third means being connected in parallel with said capacitor, said multiplier including a second capacitor actuable charge said first capacitor only on alternate half cycles of said input voltage, said second capacitor being connected to be recharged periodically, said first capacitor having a capacitance large in comparison to that of said second capacitor.

5. A pulse generator comprising: first means to supply an alternating input voltage; second means connected from said first means, said second means including an electrical energy storage device, said second means being actuable to store a predetermined maximum amount of energy in said device but only at a rate such that said maximum amount is stored over a period of time, To, such that T0 is larger than T, where T 1/f, and f is the frequency of said input voltage; third means connected to said device, said third means being actuable to discharge said device rapidly and repeatedly over time internals small in comparison to T, said third means being actuable to discharge said device at a frequency which is less than f; said first means including first and second input leads, said second means including a first resistor, first and second capacitors and first, second and third diodes, each of said diodes having an anode and a cathode, said electrical energy storage device being a third capacitor, said first resistor being connected from said second input lead to said first diode anode, said second diode anode being connected to said first diode cathode, said third diode and anode being connected to said second diode cathode, said third capacitor being connected from said third diode cathode to said first input lead, said second capacitor being connected from said first diode anode to said third diode anode, said first capacitor being connected from said first input lead to said second diode anode, said third means including a transformer having a primary winding and a secondary winding, a silicon-controlled rectifier having an anode, a cathode and a gate, said primary winding having one end connected to said third diode cathode, and its other end connected to said silicon-controlled rectifier anode, said silicon-controlled rectifier cathode being connected to said first input lead, a second resistor having one end connected to said third diode cathode, a fourth capacitor having one electrode connected to the other end of said second resistor, and its other electrode connected to said first input lead, a neon lamp connected from said other end of said second resistor to said gate, a third resistor connected from said gate to said first input lead, a pilot burner having an orifice to allow the emission of a combustible gas, two spaced spark electrodes located in a position relative to said orifice to lie approximately within any flame created by the combustion of gas emanating from said orifice, said transformer secondary winding having one end connected to one of said spark electrodes, and its other end connected to said other end of said second resistor, the other spark electrode being connected to said first input lead, said third capacitor having a capacitance in excess of twenty times that of said first capacitor, said third capacitor having a capacitance in excess of twenty times that of said second capacitor.

6. A pulse generator comprising: first means to supply an alternating input voltage; second means connected from said first means, said second means including an electrical energy storage device, said second means being actuable to store a predetermined maximum amount of energy in said device but only at a rate such that said maximum amount is stored over a period of time, To, such that To is larger than T, where T 1/f, and f is the frequency of said input voltage; third means connected to said device, said third means being actuable to discharge said device rapidly and repeatedly over time intervals small in comparison to T, said third means being actuable to discharge said device at a frequency which is less than f; said second means being a voltage multiplier, said device being a first capacitor, said third means being connected in parallel with said capacitor, said multiplier including a second capacitor actuable charge said first capacitor only on alternate half cycles of said input voltage, said second capacitor being connected to be recharged periodically, said first capacitor having a capacitance large in comparison to that of said second capacitor.