US 3629651 A
Description (OCR text may contain errors)
United States Patent 3,191,093 6/1965 Morrison et al. 315/209 3,450,942 6/1969 Segall et al 317/227 X 3,450,972 6/1969 Linkroum 315/227 X Primary Examiner-Roy Lake Assistant Examiner-Lawrence J Dahl Attorneys-Raymond J. Hitler and Plante, Hartz, Smith and Thompson ABSTRACT: A condenser discharge-type electrical pulsegenerating circuit, such as for a combustion engine ignition system, wherein two storage capacitors are charged in parallel and partially discharged in series through two control gaps and the primary winding of a high-frequency transformer, the secondary winding of which is connected in series with a highvoltage igniter gap and one of the condensers through one of said control gaps.
A a; I I2 w 7 I9 \U H 22 PATENTED U502! [97! INVENTOR.
IRVING E, LlNKROUM ATTOR EYS PULSE-GENERATING APPARATUS This invention relates to electrical apparatus and more particularly to means for controlling the operation of electrical pulse or spark-generating apparatus having an intermittently discharged storage condenser.
An object of the present invention is to provide novel control means for an electrical pulse or spark generating apparatus of the type indicated.
Another object is to provide a novel control means for an electrical pulse or spark-generating apparatus incorporating a storage condenser which is intermittently discharged through a control gap.
A further objectis toprovide meansfor controlling breakdown of the control gap, such meansbeing subjected to only a small part of the energy which is discharged through the control gap.
A still further object of the invention is to provide acontrol means for electrical pulse-generating apparatus which is simple, rugged,'and long lived, and which .provides maximum power output for a given input voltage.
The above and further objects and novels features of the invention will more fully appear from the following description when the same is read in connection withthe accompanying drawing. It is to be expressly understood, however, that the drawing is for the purpose of illustration only, and is not intended as a definition of the limits of the invention.
The single FIGURE of the drawing is a wiring diagram of one embodiment of an electrical pulse or spark generating circuit in accordance with the invention.
The circuit shown in the drawing is adapted for use asan untimed ignition circuit for jet and gas turbine type engines. The invention is not, however, limited to such uses or systems.
The ignition circuit shown is of the condenser dischargetype which is energized by a suitable source 13 of alternating electrical current or a source of interrupted direct current connected to input terminals A and -B of the ignition circuit. The current source is connected to the primary winding .10 of a power input transformer 11 having a secondary winding 12. The circuit includes a radiofrequency-filtering means 14 which is preferably, although not necessarily .employed, the means 14 being interposed between the power source and the transformer 11 to attenuate high-frequency noise generated within the ignition circuit and thus preventing interference from being transmitted to other circuits connected to the current source. I
A voltage-doubling type of energy storage means is con- Such storage means is incrementally charged by the energy source through transformer 11; the energy storage means is periodically discharged to a pulse-absorbing load, which in this instance is an ignition spark gap 29. The storage means comprises a small condenser 15 which is connected across the secondary winding 12 through a diode or half-wave rectifier 16, a second small condenser 17 connected across winding 12 through a reversely polarized diode or half-wave rectifier 19, and a main relatively large tank condenser connected across condensers 15 and 17 in series. It will be apparent that with the diodes 16 and 19 connected as shown, when the condensers are being charged the lower terminals of condensers 15, 17 and 20 are negative whereas the lower terminal of a condenser 31, to be described, is positive. Thediodes 16 and 19 may be protected against damage, the operating life thereof may be enhanced, and the required rating thereof may be minimized by providing current-limiting resistors 21 and 22 in the circuit, as shown. One side of the above-described'energy storage means is shown as being connected to a common ground 23, and the high potential side thereof is connected through a control or trigger gap to the ungrounded electrode of an ignition spark gap 29. It will be understood that, if desired, all of the points in the circuit designated 23'may be connected by a common ungrounded conductor.
The input electrode 24 of the trigger gap 25 is connected to the high potential side of the ignition circuit beyond the main tank condenser20. The output electrode 26 of the trigger gap 25 is connected to one terminal of the secondary winding 27 of a step-up transformer 28, the other terminal of the secondary winding 27 being connected to the ungrounded electrode of the ignition spark gap 29.
Connected across the electrodes 24, 26 of the trigger gap 25 is a circuit having a large resistance 30 and a small condenser 31 in series. Connected to the high potential side of the ignition circuit between the point of connection of the condenser 31 and the input terminal of the secondary winding 27 of transformer 28 is one terminal of a small resistance 33, the other terminal of which is connected to ground. One terminal of the primary winding 35 of the step-up transformer 28 is connected between the resistance 30 and the condenser 31 through a control gap 36 having an input electrode 34 and a discharge electrode 37, the other tenninal of the primary winding 35 being connected to ground. The ionizing or breakdown voltage of the trigger gap 25 is substantially less than that of the control gap 36 and much less than that of igniter gap 29.
In one successful embodiment the power transfonner 11 steps up the supply voltage, which in this instance is assumed to be 400 cycle, ll5 volt, to a level in excess of 1,600 volts peak. Each half-cycle of this voltage is rectified by one of the diodes 16, 19 to charge one of the doubler condensers 15, 17. The voltage across condensers 15, 17 is additive and therefore the voltage charging the main storage condenser 20 and trigger condenser 31 is in excess of 3,000 volts peak and of gap 25 breakdown voltage.
While the storage condenser 20 is being charged, condenser 31, which is then connected in parallel therewith, is charged through resistance 30, the charging circuit for condenser 31 being completed to ground through resistance 33. As above explained, with the diodes 16, 19 disposed as shown, the input electrode 24 of the trigger tap 25 is positive with respect to the output electrode 26 thereof. When the voltage of the charge on condensers 20 and 31 exceeds the ionizing voltage of trigger gap 25, the trigger gap breaks down, the positive end of condenser 20, that is, that connected to electrode 24 of the trigger gap 25 is momentarily connected through gap 25 to the negative terminal of condenser 31, whereby the condensers 20, 3,1 are momentarily connected in series across gap 36 and their voltages are additive. Such added voltages, which are impressed on electrode 34 of control gap 36, exceed the ionizing potential of the control gap 36. Gap 36 now begins to discharge the charge of the storage condenser 20, 31 through the primary winding 35 of the step-up transformer 28 to ionize the igniter gap 29. While this is taking place, the trigger gap 25 remains conductive, and the main part of the charge on condenser 20 is discharged to the ignition gap 29 through the secondary 27 of transformer 28.
The discharge of condensers 20 and 31 through the control gap 36, through the primary winding 35 of the transformer 28, and thence to ground results in a stepped-up voltage across the secondary 27 of transformer 28. This high voltage, on the order of 15-20 kilovolts, is also impressed across the output cable and the igniter plug 29. Once the initial arc has formed across the igniter plug 29, the energy contained in the storage condenser 20 is channeled through the control gap 25, the secondary winding 27 of transformer 28 and through the prefonned arc of the igniter gap 29 to ground.
This energy is tenned the follow-through". After the voltage across the two condensers 20, 31 decreases to low values,
their associated gaps 25, 36 deionize and the cycle repeats itself.
The circuit of the invention allows fewer turns to be employed in the secondary 27 of the high-frequency transformer 28. Hence a higher peak discharge current can be obtained through the secondary 27. These results follow from the relationships:
Surge impedance and The reduction of the number of turns in the secondary winding 27 reduces the value of L, and thus increases l and hence the peak power output for a given E. It should be noted that with this type of circuit the trigger gap 25 controls the ionization of the control gap 36. The normal ionization voltage of the gap 36 is much higher than the level at which gap 25 and hence at which the system is triggered.
Typical values of component parts which make up a satisfactory system as above described are as follows:
Condensers 20 3.5-3.6 mi. 31 0.050.065 pf.
Resistances Ohms 2i and 22 2,000
Control Gaps Ionizing Potential 25 3,000 volts 36 3,500- 4,000 volts Although only a single embodiment of the invention has been illustrated and described in the foregoing specification, it is to be expressly understood that the invention is not limited thereto but may be embodied in specifically different circuits. For example, the main tank or storage condenser 20 may be incrementally charged through other known voltage-doubling systems or through a half-wave rectifier. Transformer 11 may also be powered by an interrupted direct current source or solid state oscillator. Various other changes may also be made, such as in the electrical values suggested herein by way of example, and in the types of rectifiers illustrated without departing from the spirit and scope of the invention, as will now be apparent to those skilled in the art.
What is claimed is:
1. Electrical apparatus having a source of electrical energy, a multisection storage condenser means connected to said source so as to be incrementally charged thereby with the sections of the condenser means connected in parallel, a load circuit connected to be energized by the discharge of the storage condenser means, a first control gap interposed between one section of the storage condenser means and the load circuit, a second control gap having a breakdown potential greater than that of the first control gap and less than the sum of the voltages of the charges attainable by the parallel connected sections of the storage condenser means, first circuit means connecting the first gap to the storage condenser means so that the first gap is ionized and rendered conductive when the charge on the parallel connected sections of the storage condenser means reaches a predetermined voltage, and second circuit means for thereupon connecting said sections of the storage condenser means in series, voltage-adding relation and subjecting said gaps to the full voltage of the series connected storage condenser sections so as to ionize the second control gap and render it conductive to the discharge of the storage condenser means.
2. Electrical apparatus according to claim 1, wherein the storage condenser means has two sections, and said second circuit means includes the second gap interposed between the junction between said sections and a common conductor to which the load circuit is connected.
3. Electrical apparatus according to claim 1, wherein another section of the storage condenser means is connected in shunt with the first control gap.
4. Electrical apparatus according to claim 3, wherein said last-named section of the storage condenser means has a capacity which is but a small fraction of that of said one condenser section.
5. Electrical apparatus according to claim 1, wherein the load circuit includes an ignition spark gap.
6. Electrical apparatus according to claim 1, wherein the load circuit includes a transformer winding, the first gap has entering and discharge electrodes, and the discharge electrode is connected to the said winding of the transformer.
7. Electrical apparatus according to claim 1, comprising a transformer having primary and secondary windings, and wherein the discharge electrode of the first gap is connected to one terminal of the secondary winding.
8. Electrical apparatus according to claim 7, comprising an ignition spark gap having one electrode connected to the other terminal of the secondary winding, and wherein the second gap has an electrode connected to the primary windmg.
9. Electrical pulse-generating apparatus comprising a source of electrical energy, first and second condenser means connected in parallel across said source to be simultaneously charged thereby, a condenser discharge circuit connected across said second condenser means and comprising normally open circuit-closing means responsive to a predetennined charge on said second condenser means for closing said circuit, and a second condenser discharge circuit comprising other normally open circuit-closing means and said first and second condenser means connected in series across said firstnamed circuit-closing means, said other circuit-closing means being responsive to the sum of the charges on said first and second condenser means to close said second discharge circuit while said first-named circuit-closing means is operative.
10. Electrical pulse-generating apparatus comprising a source of electrical energy, first and second condensers connected to be charged in parallel by said source, a first spark gap connected between the positive polarity terminal of one of said condensers and the negative polarity terminal of the other of said condensers, a second spark gap connected between the other terminals of said condensers, and condenser discharge circuit means including said second spark gap connected across and adapted to be rendered conductive by the charge on said second condenser, whereby said condensers and said second spark gap become connected in series across said first spark gap while the second spark gap is conductive.
11. Electrical pulse-generating apparatus comprising a source of electrical energy, first and second storage condensers connected in parallel across said source to be simultaneously charged thereby, a first discharge circuit comprising said first condenser and a first spark gap adapted to be rendered conductive by a predetermined charge on said first condenser, and a second discharge circuit comprising said first gap and said first and second condensers connected in series across a second spark gap having a spark-over voltage less than the sum of the charges on said condensers when said first gap is rendered conductive.
12. Electrical pulse-generating apparatus comprising a source of electrical energy, first and second storage condensers connected in parallel across said source to be simultane-- ously charged thereby, first and second normally conductive spark gaps, a first discharge circuit comprising said condensers and said spark gaps connected in series, and a second discharge circuit comprising said second condenser in series with said second spark gap, the latter being adapted to be rendered conductive when said second condenser attains a predetermined charge, and said first spark gap being adapted to be rendered conductive in response to the sum of the charges on said condensers when said second spark gap is rendered conductive. 1
13. Apparatus as defined in claim 12 comprising a transformer having primary and secondary windings, said primary winding being series connected in said first discharge circuit, a third spark gap connected across said secondary winding, and a third discharge circuit comprising said second spark gap, said secondary winding and said third spark gap connected in series across said first condenser.