Systems and methods for operating a hydrogen fuelled engine provided with a spark-plug

Abstract

A system and method for operating a spark-ignited combustion engine to combust hydrogen is disclosed. An ignition coil is operatively coupled with a voltage source and a spark plug. The coil is configured to induce an electric field in the spark plug. The electric field generates partial discharges and / or corona discharges from the spark plug to ignite a hydrogen fuel and air mixture in a combustion chamber of the engine.

Description

SYSTEMS AND METHODS FOR OPERATING A HYDROGEN FUELLED ENGINE PROVIDED WITH A SPARK-PLUGCROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to, and the benefit of the filing date of, U.S. Provisional Application Ser. No. 63 / 551,269 filed on February 8, 2024, which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present application relates to systems and methods for ignition systems and / or spark plugs for internal combustion engines that use hydrogen, or a mixture of hydrogen and one or more other gases, and air for combustion.BACKGROUND

[0003] Internal combustion engines employ ignition systems that include an ignition coil and a spark plug to generate a spark to ignite the air and fuel mixture. High in-cylinder pressures at spark timing typically require a high voltage output from the ignition coil in order to generate the spark with the spark plug. Over time, the spark generation erodes the electrode so that the gap between the center electrode and the ground electrode increases. If the gap grows too large, then there is increased potential for no spark and hence misfires, ignition system damage, poor fuel economy, and other performance issues. As a result, spark plugs are changed at regular intervals so that the electrode gap does not exceed a nominal maximum allowable gap growth, ensuring that a spark will be generated at peak in-cylinder pressure of interest.

[0004] Existing approaches suffer from a number of disadvantages and shortcomings relative to internal combustion engines that combust hydrogen fuel, including those relating to serviceability, maintenance, longevity, cost, efficacy, reliability, robustness, and others. There remains a significant need for the unique systems and methods of the present disclosure.DISCLOSURE OF EXAMPLE EMBODIMENTS

[0005] For the purposes of clearly, concisely, and exactly describing example embodiments of the present disclosure, the manner, and process of making and using the same, and to enable the practice, making and use of the same, reference will now be made to certain example embodiments, including those illustrated in the figures, and specific language will be used to describe the same. It shall nevertheless be understood that no limitation of the scope of the invention is thereby created, and that the invention includes and protects such alterations, modifications, and further applications of the example embodiments as would occur to one skilled in the art.SUMMARY

[0006] Some embodiments include unique systems and methods for extending spark plug longevity and / or spark plug change interval for hydrogen combustion engines. Some embodiments include allowing the spark plug gap to exceed a nominal maximum allowable gap growth and thereafter using electrical discharges from the spark plug for ignition of hydrogen fuel in the combustion chamber at higher in-cylinder pressure conditions. Some embodiments include operating the ignition coil under open circuit conditions to generate an electric field and create electrical discharges for corona ignition and / or partial discharge ignition of hydrogen fuel in the combustion chamber. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Fig. 1 is a schematic diagram illustrating certain aspects of an example powertrain system operable with hydrogen fuel.

[0008] Fig. 2 is a flow diagram illustrating certain aspects of an example ignition system for combustion of hydrogen fuel in the system of Fig. 1.

[0009] Figs. 3 A and 3B are schematic diagrams of a triple junction region of example spark plugs for use in the ignition system of Fig. 2.

[0010] Fig. 4 is a graph illustrating voltage demand or gap growth in a spark plug over time and associated spark plug change intervals.

[0011] Fig. 5 is a partial longitudinal section view of an example spark plug for use in the ignition system of Fig. 2.

[0012] Fig. 6 is a longitudinal section view of the spark plug of Fig. 5.

[0013] Fig. 7 is an end view of the spark plug of Fig. 5.

[0014] Fig. 8 is a partial longitudinal section view of another example spark plug for use in the ignition system of Fig. 2.

[0015] Fig. 9 is a partial elevation view of an example combustion prechamber device and spark plug for use in the ignition system of Fig. 2.

[0016] Fig. 10 is a flow diagram of an example method for operating a spark-ignited combustion engine to combust hydrogen.

[0017] Fig. 11 is a flow diagram of an example method for combusting a hydrogen fuel and air mixture in a combustion chamber.

[0018] Fig. 12 is a flow diagram of another example method for operating a spark-ignited combustion engine to combust hydrogen.

[0019] Fig. 13 is a flow diagram of an example method for managing a spark plug change interval for the spark plug and / or ignition systems disclosed herein.DETAILED DESCRIPTION

[0020] With reference to Fig. 1, there is illustrated an example powertrain system 10 (also referred to herein as system 10) comprising a fueling system 14 and an engine 12. Fueling system 14 is adapted and configured to supply gaseous hydrogen for combustion to engine 12. In some embodiments, fueling system 14 may be additionally adapted and configured to supply gaseous hydrocarbon (CxHy) for combustion to engine 12 in combination with gaseous hydrogen. Engine 12 comprises combustion chambers 16a, 16n (also referred to as cylinders) of a reciprocating piston-in-cylinder type which are configured to generate mechanical power from the combustion of gaseous fuel supplied by fuel injectors 20a, 20n. System 10 may be provided in a number of forms including as a prime mover system (or component of a prime mover system) of vehicle, a genset, other power-load system.

[0021] Fuel injectors 20a, 20n are in fluid communication with respective combustion chambers 16a, 16n of the engine 12 and are structured to inject gaseous fuel that is provided to their respective combustion chambers 16a, 16n. In the illustrated embodiment, fuel injectors 20 are configured and provided as port fuel injectors configured to inject fuel directly into respective ports of intake manifold 18 leading to respective combustion chambers 16 of engine 12. Other embodiments may include other types and configurations of injectors such as direct fuel injectors configured to inject fuel directly into respective combustion chambers of engine 12. In the illustrated embodiment, two fuel injectors 20a, 20n and two combustion chambers 16a, 16n are depicted, it being appreciated that engine 12 may include fewer or greater numbers of fuel injectors and combustion chambers arranged and configured in a variety of manners.

[0022] In the illustrated embodiment, fueling system 14 includes a hydrogen fuel supply 22 and a gaseous fuel injection system 24. Injection system 24 may include one or more rails and one or more sets of injectors (e.g, injectors 20a, 20n or other injectors) operatively coupled with and supplied with gaseous fuel from a respective one of the one or more rails. The one or more rails are, in turn, configured to receive pressurized fuel from hydrogen fuel supply 22.

[0023] In some embodiments, fueling system 14 may include a gaseous hydrocarbon (e.g., natural gas, wellhead gas, biogas, or other gaseous hydrocarbons) fuel supply 26 which is configured to supply gaseous hydrocarbon fuel for combustion to engine 12. In the illustrated example gaseous hydrocarbon fuel supply 26 is adapted to introduce hydrogen and gaseous hydrocarbon fuel into the gaseous fuel injection system via a valve and mixer system 28 whichcan selectably vary the relative proportion of hydrogen and gaseous hydrocarbon provided for combustion by engine 12. In other embodiments, gaseous hydrocarbon fuel supply 26 may be provided with separate rails and injectors, which may be adapted to inject gaseous hydrocarbon fuel into respective ports or directly into respective cylinders separately from the rails and injectors that supply hydrogen for combustion by engine 12.

[0024] In some embodiments, fueling system 14 may include additional elements such as a compressor configured to compress gaseous fuel received from the fuel tank supply. Compressed gaseous fuel can be supplied to the one or more rails. An accumulator as well as electronically controllable valves configured to control supply of gaseous fuel to and from the accumulator and / or the one or more rails may also be provided.

[0025] System 10 further includes one or more ignition devices such as spark plugs 110a, 1 lOn associated with respective ones of the combustion chambers 16a, 16n. As discussed further below, spark plugs 110 generate a spark and / or an electric field with partial discharges and / or corona discharges of electrical energy to ignite the hydrogen fuel and air mixture in the associated combustion chamber 16.

[0026] System 10 further includes an electronic control system (ECS) 30 in communication with engine 12 and configured to control one or more aspects of engine 12, including controlling the injection of fuel into engine 12 via the fuel injectors 20 and combustion of the hydrogen fuel air mixture in the combustion chambers 16 with spark plugs 110. Accordingly, ECS 30 may be in communication with the fuel injectors 20 and spark plugs 110 and configured to command each fuel injector 20 on and off at prescribed times to inject fuel into the engine 12 as desired and control the spark / ignition timing of spark plugs 110. ECS 30 include at least one electronic control unit (ECU) 32 configured to execute operations of ECS 30 as described further herein and, in some embodiment, may include additional ECUs configured to execute operations of ECS 30 as described further herein.

[0027] With reference to Fig. 2, there is illustrated an ignition system 100 (also referred to herein as system 100) which may be provided and implemented in a powertrain system such as system 10. In an embodiment, system 100 is configured as an inductive ignition system. It shall be appreciated that other embodiments may utilize other types of ignition systems including, for example, a capacitive discharge ignition system.

[0028] System 100 includes an ignition circuit 102 comprising at least one ignition coil 104 operatively coupled with a voltage supply 106 and a switch 108 controllable to regulate a current in the ignition circuit 102. In the illustrated example, switch 108 is operatively coupled with and adapted to be controlled by controller 32 of ECS 30 to regulate an ignition current in the ignition circuit 102. The switch 108 may be provided in a number of forms including, for example, an insulated gate bipolar transistor (IGBT), a power metal oxide silicon field effect transistor (MOSFET) such as a silicon carbide (SiC) MOSFET, or other types of switching devices as will occur to one of skill in the art with the benefit and insight of the present disclosure.

[0029] Ignition circuit 102 is also operatively coupled with spark plug 110. Ignition circuit 102 may include one or more current protection devices (not shown), for example, one or more diodes. Ignition circuit 102 may also include resistors (not shown) coupled with ignition coil 104 and spark plug 110, with the ignition coil 104 and ground, and with any current protection devices and ground.

[0030] During operation of ignition system 100, controller 32 may close or otherwise operate switch 108 to cause the ignition current to flow to and from ignition coil 104. As a result, an ignition current flows to spark plug 110. In response, when the spark plug 110 becomes sufficient charged, a spark and / or a partial discharge and / or corona discharge 113 of electrical energy is generated in combustion chamber 16 to ignite a hydrogen fuel and air mixture. The hydrogen fuel may be entirely a hydrogen-based fuel such as gaseous hydrogen (H2), or a mixture or combination of H2 and gaseous hydrocarbon (CXHY).

[0031] Controller 32 may be provided in a number of forms including, for example, as a microprocessor-based or other integrated circuit-based electronic controller. Controller 32 may be provided as a component of an electronic control system such as ECS 30 or another electronic control system, and may be provided as a stand-alone or discrete control component or implemented in combination with other control components in a variety of manners as will occur to one of skill in the art with the benefit and insight of the present disclosure.

[0032] As will be appreciated by the description that follows, the techniques described herein relating to spark plug ignition parameters can be implemented in full or part by ECS 30, which may include one or more controllers for controlling different aspects of the system 10. In one form, the ECS 30 comprises one or more electronic control units (ECU) 32 such as an engine control unit or engine control module. The ECS 30 may be comprised of digital circuitry, analogcircuitry, or a hybrid combination of both of these types. Also, the ECS 30 may be programmable, an integrated state machine, or a hybrid combination thereof. The ECS 30 may include one or more Arithmetic Logic Units (ALUs), Central Processing Units (CPUs), memories, limiters, conditioners, filters, format converters, or the like which are not shown to preserve clarity. In one form, the ECS 30 is of a programmable variety that executes algorithms and processes data in accordance with operating logic that is defined by programming instructions (such as software or firmware). Alternatively or additionally, operating logic for the ECS 30 may be at least partially defined by hardwired logic or other hardware.

[0033] Referring to Fig. 3A, an embodiment of a spark plug is shown and designated as spark plug 210. In Fig. 3, one possible triple junction region 212 of spark plug 210 is shown, and further examples of spark plug 210 with one or more triple junction regions are discussed below. It should be understood that the principles associated with triple junction region(s) 212 of spark plug 210 are also applicable to a triple junction region(s) 112 of spark plug 110.

[0034] Spark plug 210 includes a center electrode 214 and an insulator nose 216 around center electrode 214. Center electrode 214 is made from a metal material or alloys thereof such as copper, nickel, chromium, iridium, or platinum, for example. Insulator nose 216 is made from a solid insulating material, such as ceramic.

[0035] In an embodiment, triple junction region 212 is located where insulator nose 216 separates from center electrode 214 to form an air gap 218. Air gap 218 begins at a separation location 220 formed by center electrode 214 and insulator nose 216. Air gap 218 includes a first zone 222 and a distally spaced second zone 224 between center electrode 214 and insulator nose 216. The current applied to spark plug 210 creates an electric field in air gap 218. The electric field is of sufficient intensity to create electric discharges, such as partial discharges and / or corona discharges, to ignite hydrogen gas in the combustion chamber 16. Other embodiments contemplate one or more triple junctions formed at any location near the distal end of the spark plug wherein an air gap is formed between two different types of material.

[0036] In an embodiment, first zone 222 is about 2-3 millimeters from separation location 220, and second zone 224 is more than 5 millimeters from separation location 220. First zone 222 includes an electric field intensity that is greater than second zone 224. In the illustrated embodiment, air gap 218 is triangular, but could also be square or rectangular in shape, such as shown in Fig. 3A, so long as air gap 218 is sufficiently tight for electric field intensification togenerate discharges of electrical energy, such as partial discharges along a surface of insulator nose 216 and / or corona discharges in air gap 218.

[0037] Hydrogen gas fuel does not require as much energy for ignition as other gaseous fuels, such as natural gas and other hydrocarbon fuels. Even under open circuit conditions for ignition coil 104, the electrical discharges generated by the electric field at triple junction region 212 are sufficient to ignite a hydrogen fuel and air mixture in combustion chamber 16. As a result, it is not necessary to generate a spark between the center electrode and the ground electrode of spark plug 210 to ignite the hydrogen fuel and air mixture in combustion chamber 16.

[0038] With reference to Fig. 4, a graph 400 shows spark plug change interval along the x- axis and kV demand or gap growth along the y-axis. Ignition coil 104 and spark plug 110, 210 can operate at maximum voltage 402, i.e. the open circuit voltage, of coil 104, since a spark is not required for ignition at high in-cylinder pressure conditions. Prior ignition coils and spark plugs operate at a maximum allowable voltage 404 that is less than maximum voltage 402 due to variation in ignition systems. When the spark plug gap growth has increased from time tO (new spark plug) to time tl such that more than the maximum allowable voltage 404 is required to generate a spark at high in-cylinder pressure, the prior spark plugs are changed to new spark plugs. The spark plug change interval at tl is thus established to limit the allowable gap growth between the center electrode and ground electrode. This ensures that a spark is always available to be generated for ignition of the fuel and air mixture at all in-cylinder pressures and avoid misfires and other performance issues.

[0039] In contrast, the present disclosure allows the gap growth in spark plug 110, 210 to continue past time tl to time t2 and the maximum voltage 402, after which no spark is able to be generated at high in-cylinder pressure conditions due to spark plug gap growth. The spark plug 110, 210 is continued in use from time t2 to time t3 to operate in a hybrid spark corona ignition mode, using open circuit conditions of ignition coil 104 and spark plug 210. Time t3 depends on the capability of ignition coil 104 to operate at open circuit voltage continuously and reliably generate an electrical field for corona ignition using partial discharges and / or corona discharges.

[0040] The present disclosure contemplates coil diagnostic methods to understand that the ignition system is running in open circuit conditions. Coil diagnostics includes, for example,determining changes in spark voltage, determining secondary currents, measurements of expected electrical disturbances on the secondary circuit reflected on the primary, etc.

[0041] In the hybrid spark corona ignition mode, spark plug 110, 210 continues to create a spark for ignition of the hydrogen fuel and air mixture at lower in-cylinder pressures. At higher cylinder pressures in which the spark plug gap is too great to generate a spark at the maximum coil voltage 402, corona ignition using partial discharges and / or corona discharges to ignite the hydrogen fuel and air mixture is employed for combustion. Time t3 establishes a new spark plug change interval from time tO to time t3 that is at least 50% greater than the spark plug change interval from tO to time tl. It is believed that time t3 may be able to be extended to be two to three times longer than change interval established by time tl. Any suitable technique for determining a spark plug change event at time t3 are contemplated. For example, the change interval at time t3 could be based on a number of observed open circuit events, etc.

[0042] It is contemplated that ignition coil 104 can be operated at its maximum voltage with the maximum primary current in ignition circuit 102. The maximum primary current can be, for example, limited by the maximum allowed IGBT temperature at 105 degrees Celsius open air condition. The open circuit voltage will induce the electric field in triple junction region 112, 212 to provide corona ignition with partial discharges and / or corona discharges. The spark plug dielectric for spark plugs 110, 210 can be, for example, 40 kV and provided with a long insulator length to contain the high voltage, especially when cold, to provide spark plug durability.

[0043] Ignition circuit 102 may also be provided with a high clamping voltage (e.g., 40kV) and high energy to sustain open load dumps under open circuit conditions. The transformer windings / chamber of ignition col 104 can be configured to evenly distribute the secondary voltage. Boot and coil dielectrics are also configured to sustain the high voltage without damage. For example, ignition coil 104 can be configured with a lossy magnetic core to provide a high available voltage and low energies.

[0044] In addition, the tubes or openings in engine 12 to receive the spark plugs 110, 210 can be changed to magnetically impermeable electrically conductive tubes or a dielectric tube. These can reduce parasitic capacitance, increase available voltage, and reduce energy losses in eddy currents in the magnetically impermeable but electrically conductive tube.

[0045] Referring to Figs. 5-7, further details of an example of spark plug 210 are shown. Spark plug 210 includes a ground electrode 230 surrounding insulator nose 216. Groundelectrode 230 includes a flat distal end wall 234 having a plurality of flame holes 232 positioned therearound in communication with one or more triple junction regions 212, 213. In other embodiments, distal end wall may include a single hole, one or more slots, gaps, etc. to provide a flame path.

[0046] Ground electrode 230 forms a gap 236 with center electrode 214.As discussed above, gap 236 grows over time due to erosion created by the sparking between center electrode 214 and ground electrode 230. Electrical discharges, such as corona discharges and partial discharges, created at triple junction region 212 can be used to ignite the hydrogen fuel and air mixture under operating condition in which a spark cannot be generated. Corona discharges may also be created along rough points or microscopic tips along the center electrode 214 and other surfaces or points with high electric fields. Ground electrode 230 also provides at least partial shielding of triple junction region 212, shielding the partially discharges from flow velocities that may quench the ignition kernel of the electrical discharges.

[0047] Referring to Fig. 8, further details of an example of spark plug 110 are shown. Spark plug 110 includes a ground electrode 130 surrounding insulator nose 116. Ground electrode 130 includes a J-shaped extension 132 that extends distally of center electrode 114. Extension 132 of ground electrode 130 forms a gap 136 with center electrode 114. As discussed above, gap 136 grows over time due to erosion created by the sparking between center electrode 114 and ground electrode 130. Electrical discharges, such as corona discharges and partial discharges, created at tr2iple junction region(s) 112, 113 can be used to ignite the hydrogen fuel and air mixture under operating condition in which a spark cannot be generated.

[0048] Referring to Fig. 9, further details of a combustion prechamber device 150 are shown, which can be used with spark plug 110, 210. Combustion prechamber device 150 includes a housing 152 mounted to a distal end of spark plug 110, 210. Housing 152 includes bores 154 in fluid communication with an interior prechamber 156 defined by housing 152. The triple junction region(s) 112, 212 is located within housing 152 and is shielded from high flow velocities in combustion chamber 16, which may inhibit quenching of the ignition kernel of the electrical discharges.

[0049] With reference to Fig. 10, an embodiment of a method 1000 of operating spark- ignited combustion engine 12 to combust hydrogen is shown. Method 1000 includes an operation 1002 to operate ignition system 100, which includes ignition coil 104 operativelycoupled with voltage source 106 and spark plug 110, 210. During the operating, method 1000 includes an operation 1004, which generates electrical discharges, such as corona discharges and partial discharges, from spark plug 110, 210. Method 1000 further includes operation 1006 to ignite the hydrogen fuel and air mixture in combustion chamber 16 of engine 12 with the electrical discharges.

[0050] In an embodiment, ignition coil 104 is an inductive ignition coil or a capacitive discharge ignition coil. In an embodiment, operation 1002 includes operating ignition coil 104 in an open circuit condition to generate the electrical discharges.

[0051] Referring to Fig. 11, an embodiment of a method 1100 of combusting a hydrogen fuel and air mixture in combustion chamber 16 of spark-ignited combustion engine 12 is provided. Method 1100 includes an operation 1102 to operate ignition coil 104 to induce an electric field at a triple junction region(s) 112, 113, 212, 213 of spark plug 110, 210. Method 1100 includes an operation 1104 to ignite the hydrogen fuel and air mixture in combustion chamber 16 with electrical discharges, such as corona discharges and partial discharges, from triple junction region(s) 112, 113, 212, 213 of spark plug 110, 210 caused by the electric field. In an embodiment, operation 1102 includes operating ignition coil 104 in an open circuit condition.

[0052] Referring to Fig. 12, an embodiment of a method 1200 of operating spark-ignited combustion engine 12 to combust hydrogen is provided. Method 1200 includes an operation 1202 to operate ignition system 100 including ignition coil 104 operatively coupled with voltage source 106 and spark plug 110, 210. Method 1200 further includes an operation 1204 to, during the operating of ignition system 100, generate a spark from spark plug 110, 210 with the ignition coil 104 to ignite the hydrogen fuel and air mixture under a first operating condition. Method 1200 includes an operation 1204 to, during the operating of ignition system 100, generate electrical discharges, such as corona discharges and partial discharges, from spark plug 110, 210 with ignition coil 104 to ignite the hydrogen fuel and air mixture under a second operating condition.

[0053] In an embodiment, the first operating condition is an engine speed / load or in-cylinder pressure that is less than the engine speed / load or in-cylinder pressure under the second operating condition. In an embodiment, operation 1202 includes operating ignition coil 104 in an open circuit condition to generate the electrical discharges. .

[0054] Referring to Fig. 13, an embodiment of a method 1300 for managing a spark plug change interval for spark plugs 110, 210 and / or ignition coil 104 of ignition system 100 according to the present disclosure is provided. Method 1300 includes an operation 1302 to record a number of sparks for each spark plug 110, 210. The recorded number of sparks can be stored in ECS 30, ECU 32, or other electronic control system or electronic control unit in operation communication with ignition system 100. In an embodiment, operation 1302 includes recording or counting the number of sparks that occur in each of a number of bins or buckets that are defined by different ranges of engine speeds and an associated range of engine load(s) for each range of engine speed.

[0055] Method 1300 continues at operation 1304 to determine a time at which ignition coil 104 operates with open circuit conditions. In an embodiment, operation 1304 includes receiving ignition coil diagnostics for ignition coil 104 at ECS 30, ECU 32, or other electronic control system or electronic control unit in operation communication with ignition system 100. In an embodiment, operation 1304 includes recording the time at which the open circuit condition occurs for ignition coil 104 at ECS 30, ECU 32, or other electronic control system or electronic control unit in operation communication with ignition system 100.

[0056] Method 1300 continues from operation 1304 at operation 1306 to record a number of sparks for each spark plug 110, 210 that occur after the time at which the open circuit condition is detected. The number of sparks recorded during operation 1306 can also be stored in ECS 30, ECU 32, or other electronic control system or electronic control unit in operation communication with ignition system 100. In an embodiment, operation 1306 includes recording or counting the number of sparks that occur in each of the number of bins or buckets for different ranges of engine speeds and associated ranges of engine loads that are used in operation 1302 and differentiating the number of sparks recorded during operation 1306 from the number sparks recorded during operation 1302.

[0057] Method 1300 continues from operation 1306 at conditional 1308 to determine if the number of sparks that are recorded during operation 1306 are greater than a spark plug threshold number of sparks. If conditional 1308 is NO, method 1300 returns to operation 1306. If conditional 1308 is YES, method 1300 continues at conditional 1310.

[0058] Conditional 1310 determines if the number of sparks that are recorded at operation 1306 are greater than an ignition coil threshold number of sparks. In an embodiment, theallowable number of sparks for the ignition coil threshold is greater than the allowable number of sparks for the spark plug threshold. If conditional 1310 is NO, method 1300 continues at operation 1312 to indicate an alert to change the spark plugs 110, 210. Method 1300 continues from operation 1312 to return to operation 1306 and continues to record the number of sparks that occur after the open circuit condition is detected.

[0059] If conditional 1310 is YES, method 1300 continues at operation 1314 to indicate an alert to change the ignition coil 104. Operation 1314 can also indicate an alert to change the spark plugs 110, 210 in addition to the ignition coil 104. Method 1300 continues from operation 1314 at 1316 to reset the spark count after the ignition coil is changed. After the reset at operation 1314, method 1300 continues at operation 1302 and method 1300 repeats. The alerts at operations 1312, 1314 can be indicated to the driver, fleet management system, or other user or owner via a warning light, a fault code, a diagnostic tool, a prognostics tool, and / or other suitable technique.

[0060] Methods 1000, 1100, 1200, 1300 are exemplary processes of operating systems 10 and / or 100. All or a portion of methods 1000, 1100, 1200, 1300 may be implemented in ECS 30, ECU 32, or another electronic control system or electronic control unit, in operative communication with ignition system 100. Methods 1000, 1100, 1200, 1300 may be implemented in and performed by one or more components of an electronic control system such as one or more electronic control units (e.g., ECU 32 and / or other electronic control units) and / or by other electronic control system componentsA

[0061] Various aspects of the present disclosure are contemplated. According to one aspect, a method of operating a spark-ignited combustion engine to combust hydrogen is disclosed. The method includes operating an ignition system comprising an ignition coil operatively coupled with a voltage source and a spark plug; during the operating generating electrical discharges from the spark plug; and igniting a hydrogen fuel and air mixture in a combustion chamber of the engine with the electrical discharges.

[0062] In an embodiment, the ignition coil is an inductive ignition coil or a capacitive discharge ignition coil.

[0063] In an embodiment, operating the ignition system includes operating the ignition coil in an open circuit condition to generate the electrical discharges.

[0064] According to another aspect, a method of combusting a hydrogen fuel and air mixture in a combustion chamber of a spark-ignited combustion engine is provided. The method includes operating an ignition coil to induce an electric field at a triple junction region of a spark plug; and igniting the hydrogen fuel and air mixture in the combustion chamber with electrical discharges from the triple junction region of the spark plug caused by the electric field.

[0065] In an embodiment, operating the ignition coil includes operating the ignition coil in an open circuit condition.

[0066] In an embodiment, combustion of hydrogen includes combustion of hydrogen mixed with one or more other gaseous fuels.

[0067] According to another aspect, a method of operating a spark-ignited combustion engine to combust hydrogen is provided. The method includes operating an ignition system comprising an ignition coil operatively coupled with a voltage source and a spark plug; during the operating generating a spark from the spark plug with the ignition coil to ignite the hydrogen fuel and air mixture under a first operating condition; and during the operating generating electrical discharges from the spark plug with the ignition coil to ignite the hydrogen fuel and air mixture under a second operating condition.

[0068] In an embodiment, the first operating condition is an engine speed / load or in-cylinder pressure that is less than the engine speed / load or in-cylinder pressure under the second operating condition.

[0069] In an embodiment, operating the ignition system includes operating the ignition coil in an open circuit condition to generate the electrical discharges.

[0070] In an embodiment of the methods, the electrical discharges include corona discharges and / or partial discharges.

[0071] According to another aspect of the disclosure, a system for operating a spark-ignited combustion engine to combust hydrogen is provided. The system includes an ignition coil operatively coupled with a voltage source and a spark plug operatively coupled with the ignition coil. The ignition coil is configured to induce an electric field in the spark plug, the electric field generating electrical discharges from the spark plug to ignite a hydrogen fuel and air mixture in a combustion chamber of the engine.

[0072] In an embodiment, the spark plug includes at least one triple junction region in or adjacent the combustion chamber, and the electrical discharges are generated in the triple junction region.

[0073] In a further embodiment, the spark plug includes a center electrode and an insulator nose around the center electrode, and the triple junction region is formed at a junction formed by an air gap between a distal end of the insulator nose and the center electrode.

[0074] In a further embodiment, the spark plug includes a ground electrode extending around the insulator nose. In a further embodiment, the ground electrode includes a plurality of holes for gas and flame exchange with the combustion chamber.

[0075] In a further embodiment, the electrical discharges are partial discharges that occur on the insulator nose at the triple junction region.

[0076] In a further embodiment, the spark plug includes a J-shaped ground electrode.

[0077] In a further embodiment, the at least one triple junction region is shielded from external flows in the combustion chamber.

[0078] In a further embodiment, the system includes a combustion prechamber device, and the at least one triple junction region is positioned in the combustion prechamber device.

[0079] In an embodiment, the ignition coil is an inductive ignition coil or a capacitive discharge ignition coil.

[0080] In an embodiment of the system, the electrical discharges include corona discharges and / or partial discharges.

[0081] According to another aspect of the disclosure, a method of operating a spark-ignited combustion engine to combust hydrogen is provided. The method includes operating an ignition system comprising an ignition coil operatively coupled with a voltage source and a spark plug; determining a time at which the ignition coil operates in an open circuit condition to generate electrical discharges; recording a number of sparks generated by the spark plug before and after the time of the open circuit condition; indicating a spark plug change alert for the spark plug in response to the number of sparks exceeding a spark plug threshold number of sparks; and indicating an ignition coil change alert for the ignition coil in response to the number of sparks generated by the spark plug after the time of the open circuit condition exceeding an ignition coil threshold number of sparks.

[0082] In an embodiment, the method includes changing the spark plug in response to the spark plug change alert being indicated; and in response to the number of sparks not exceeding the ignition coil threshold number of sparks, continuing to record the number of sparks generated by the spark plug after the time of the open circuit condition.

[0083] In an embodiment, the method includes changing the ignition coil in response to the ignition coil change alert being indicated; and resetting the number of sparks after changing the ignition coil.

[0084] It shall be appreciated that terms such as “a non-transitory memory,” “a non- transitory memory medium,” and “a non-transitory memory device” refer to a number of types of devices and storage mediums which may be configured to store information, such as data or instructions, readable or executable by a processor or other components of a computer system and that such terms include and encompass a single or unitary device or medium storing such information, multiple devices or media across or among which respective portions of such information are stored, and multiple devices or media across or among which multiple copies of such information are stored.

[0085] It shall be appreciated that terms such as “determine,” “determined,” “determining” and the like when utilized in connection with a control method or process, an electronic control system or controller, electronic controls, or components or operations of the foregoing refer inclusively to a number of acts, configurations, devices, operations, and techniques including, without limitation, calculation or computation of a parameter or value, obtaining a parameter or value from a lookup table or using a lookup operation, receiving parameters or values from a datalink or network communication, receiving an electronic signal (e.g., a voltage, frequency, current, or pulse-width modulation (PWM) signal) indicative of the parameter or value, receiving output of a sensor indicative of the parameter or value, receiving other outputs or inputs indicative of the parameter or value, reading the parameter or value from a memory location on a computer-readable medium, receiving the parameter or value as a run-time parameter, and / or by receiving a parameter or value by which the interpreted parameter can be calculated, and / or by referencing a default value that is interpreted to be the parameter value.

[0086] While example embodiments of the disclosure have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only certain example embodiments have beenshown and described and that all changes and modifications that come within the spirit of the claimed inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicates that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and / or “a portion” is used the item can include a portion and / or the entire item unless specifically stated to the contrary.

Claims

WHAT IS CLAIMED IS:

1. A method of operating a spark-ignited combustion engine to combust hydrogen, the method comprising: operating an ignition system comprising an ignition coil operatively coupled with a voltage source and a spark plug; during the operating generating electrical discharges from the spark plug; and igniting a hydrogen fuel and air mixture in a combustion chamber of the engine with the electrical discharges.

2. The method of claim 1, wherein the ignition coil is an inductive ignition coil or a capacitive discharge ignition coil.

3. The method of claim 1, wherein operating the ignition system includes operating the ignition coil in an open circuit condition to generate the electrical discharges.

4. The method of claim 1, wherein the electrical discharges include corona discharges and / or partial discharges.

5. A method of combusting a hydrogen fuel and air mixture in a combustion chamber of a spark-ignited combustion engine, the method comprising: operating an ignition coil to induce an electric field at a triple junction region of a spark plug; and igniting the hydrogen fuel and air mixture in the combustion chamber with electrical discharges from the triple junction region of the spark plug caused by the electric field.

6. The method of claim 5, wherein operating the ignition coil includes operating the ignition coil in an open circuit condition.

7. The method of claim 5, wherein the electrical discharges include corona discharges and / or partial discharges.

8. A method of operating a spark-ignited combustion engine to combust hydrogen, the method comprising: operating an ignition system comprising an ignition coil operatively coupled with a voltage source and a spark plug; during the operating generating a spark from the spark plug with the ignition coil to ignite the hydrogen fuel and air mixture under a first operating condition; and during the operating generating electrical discharges from the spark plug with the ignition coil to ignite the hydrogen fuel and air mixture under a second operating condition.

9. The method of claim 8, wherein the first operating condition is an engine speed / load or in-cylinder pressure that is less than the engine speed / load or in-cylinder pressure under the second operating condition.

10. The method of claim 8, wherein operating the ignition system includes operating the ignition coil in an open circuit condition to generate the electrical discharges.

11. The method of claim 8, wherein the electrical discharges include corona discharges and / or partial discharges.

12. A system for operating a spark-ignited combustion engine to combust hydrogen, the system comprising: an ignition coil operatively coupled with a voltage source; and a spark plug operatively coupled with the ignition coil, wherein the ignition coil is configured to induce an electric field in the spark plug, the electric field generating electrical discharges from the spark plug to ignite a hydrogen fuel and air mixture in a combustion chamber of the engine.

13. The system of claim 12, wherein the spark plug includes at least one triple junction region in or adjacent the combustion chamber, the electrical discharges being generated in the triple junction region.

14. The system of claim 13, wherein the spark plug includes a center electrode and an insulator nose around the center electrode, and the triple junction region is formed at a junction formed by an air gap between a distal end of the insulator nose and the center electrode.

15. The system of claim 14, wherein the spark plug includes a ground electrode extending around the insulator nose.

16. The system of claim 15, wherein the ground electrode includes a plurality of holes for gas and flame exchange with the combustion chamber.

17. The system of claim 16, wherein the electrical discharges are partial discharges that occur on the insulator nose at the triple junction region.

18. The system of claim 14, wherein the spark plug includes a J-shaped ground electrode.

19. The system of claim 13, wherein the at least one triple junction region is shielded from external flows in the combustion chamber.

20. The system of claim 13, further comprising a combustion prechamber device, wherein the at least one triple junction region is positioned in the combustion prechamber device.

21. The system of claim 12, wherein the ignition coil is an inductive ignition coil or a capacitive discharge ignition coil.

22. The system of any of claims 12-21, wherein the electrical discharges include corona discharges and / or partial discharges.

23. A method of operating a spark-ignited combustion engine to combust hydrogen, the method comprising:operating an ignition system comprising an ignition coil operatively coupled with a voltage source and a spark plug; determining a time at which the ignition coil operates in an open circuit condition to generate electrical discharges; recording a number of sparks generated by the spark plug before and after the time of the open circuit condition; indicating a spark plug change alert for the spark plug in response to the number of sparks exceeding a spark plug threshold number of sparks; and indicating an ignition coil change alert for the ignition coil in response to the number of sparks generated by the spark plug after the time of the open circuit condition exceeding an ignition coil threshold number of sparks.

24. The method of claim 23, further comprising: changing the spark plug in response to the spark plug change alert being indicated; and in response to the number of sparks not exceeding the ignition coil threshold number of sparks, continuing to record the number of sparks generated by the spark plug after the time of the open circuit condition.

25. The method of claim 23, further comprising: changing the ignition coil in response to the ignition coil change alert being indicated; and resetting the number of sparks after changing the ignition coil.

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