# US 5,347,422 A · Apparatus and method for an ignition system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,347,422 A - Document ID: US5347422A - Status: Granted - Kind: A - Application number: 07/942,654 - Filed: 1992-09-09 - Granted: 1994-09-13 - Earliest claimed: 1992-09-09 - Assignees: Unison Industries Limited Partnership - Inventors: Kenneth W. Smith; Bruce E. Dolmovich; John R. Frus - Web page: https://patentgrep.com/patent/US5347422A ## CPC - F02P 17/12: Testing characteristics of the spark, ignition voltage or current (testing of sparking plugs H01T13/60) - F02P 3/0892: {using digital techniques} - F02P 15/003: {Layout of ignition circuits for gas turbine plants (ignition of gas turbine plants per se F02C7/26)} - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - H03K 3/53: by the use of an energy-accumulating element discharged through the load by a switching device controlled by an external signal and not incorporating positive feedback (H03K3/335 takes precedence) - H02M 1/0032: {Control circuits allowing low power mode operation, e.g. in standby mode} - Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes - F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00) - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract An ignition system is provided that marries a free-running discharge circuit with a fast-charging, high voltage converter without resulting in an excessive rate of discharge. To this end, the free-running discharge circuit employs a passive switch embodied either as a spark-gap device or a passive network of semiconductor elements. A feedback circuit detects discharge events at the discharge circuit and, in response thereto, selectively enables and disables the fast-charging converter. A spark rate clock is integrated into the feedback circuit for the purpose of setting the average discharge rate to a predetermined value. ## Claims ### Claim 1 An ignition system responsive to a power source for igniting fuel in a turbine engine, the system comprising: an energy storage device; means for pumping energy from the power source into the energy storage device; an output circuit including an igniter plug; a passive device for conducting energy from the energy storage device into the output circuit in order to create a spark event when the energy held in the energy storage device reaches a level that breaks down a high impedance in the passive device, which otherwise prevents the flow of energy from the energy storage to the output circuit; a sensor for sensing when the spark event occurs and providing a signal indicative thereof; and means responsive to the signal from the sensor for selectively enabling and disabling the pumping means so as to control the rate at which successive spark events occur. ### Claim 2 (depends on 1) An ignition system as set forth in claim 1 wherein the means for selectively enabling and disabling the pumping means includes a bistable output voltage for enabling and disabling the pumping means. ### Claim 3 (depends on 2) An ignition system as set forth in claim 2 wherein the means for selectively enabling and disabling the pumping means includes a spark rate clock and a means for synchronizing clock pulses from the spark rate clock with transitions of the bistable output voltage, which transitions are in response to the signal from the sensor; thereby providing an average spark rate proportional to the frequency of the clock pulses. ### Claim 4 (depends on 1) An ignition system as set forth in claim 1 wherein the passive device is a spark gap device. ### Claim 5 (depends on 1) An ignition system as set forth in claim 1 wherein the passive device is a network of semiconductor elements. ### Claim 6 (depends on 1) An ignition system as set forth in claim 1 wherein the sensor is a voltage divider network and an isolation transformer. ### Claim 7 (depends on 1) An ignition system as set forth in claim 1 including a diagnostic means responsive to the signal from the sensor for detecting an unhealthy spark event. ### Claim 8 In an ignition system responsive to a power source for igniting fuel in a turbine engine, wherein the ignition system includes an energy storage device and a passive device coupling the energy storage device to an igniter plug, a method for generating successive spark events at a spark gap of the igniter plug comprising the following sequential steps: (a) enabling the pumping of energy into the energy storage device; (b) breaking down a high impedance barrier in the passive device in order to transform the barrier to a low impedance path connecting the energy storage device and the igniter plug; (c) transferring the energy stored in the energy storage device into the igniter plug by way of the low impedance path in the passive device and thereby creating a spark event at the spark gap of the igniter plug; (d) sensing the occurrence of the spark event; (e) disabling the pumping of energy into the energy storage device in response to the sensing of the occurrence of the spark event; and (f) repeating the foregoing steps (a) through (e) so as to establish a controlled rate of successive spark events at the spark gap. ### Claim 9 (depends on 8) A method as set forth in claim 8 wherein the initiation of each repeated step (a) is in synchronization with a reference frequency, thereby providing the ignition system with a constant average spark rate even though the time period between steps (a) through (e) vary as the steps are repeated.