Ignition coil dwell control

Abstract

The invention relates to ignition coil dwell control. A method for controlling dwell time in an ignition system of an internal combustion engine is provided. In one example, a method includes adjusting dwell based on engine operating conditions, and further adjusting dwell in a manner proportional to existing spark plug condition. By continuously evaluating spark plug condition during operation of the internal combustion engine, premature wear of the spark plug can be prevented, resulting in an extended service life of the spark plug and other ignition system components.

Description

TECHNICAL FIELD

[0001] The present specification generally relates to methods and systems for controlling a dwell time in an ignition system of an internal combustion engine proportional to a spark plug life. BACKGROUND

[0002] Engine systems with spark ignition modules can be configured to achieve peak power output to meet engine operating requirements. In an inductive spark ignition engine, an ignition coil can provide the necessary spark energy to cause a spark plug to ignite a homogeneous air-fuel mixture in a combustion chamber, thereby causing engine rotation. The ignition coil includes a primary winding and a secondary winding. One end of the primary winding is connected to a battery (e.g., 12V DC), where a high peak current flows steadily from the battery through the primary winding of the coil to build an electromagnetic field in the ignition coil core, and the other end is connected to a switch mechanism. The tip of the spark plug contains a gap that voltage must jump across to produce a spark. To actuate the spark plug for ignition, the switch mechanism is opened, thereby causing the magnetic field within the primary winding to collapse rapidly and induce a high voltage current in the secondary winding of the ignition coil, which is connected to the spark plug. The high voltage in the ignition coil across the gap between the electrodes of the spark plug produces spark energy (e.g., creates a spark) to ignite the air-fuel mixture for combustion.

[0003] The spark energy provided by the ignition coil is generated by the time current flows through the ignition coil. The time current flows within the ignition coil, or in other words, the period of time the ignition coil is charged, is referred to as the dwell or dwell time. The energy of the ignition spark can directly affect engine performance, where an ignition spark with low energy due to a reduced dwell time can result in unreliable combustion. On the other hand, high spark energy and longer spark duration can effectively prevent engine misfire and can be obtained by longer dwell times. However, while high current supplied to the ignition coil during conditions of high engine speed and load can result in high spark energy with longer spark duration, the high current supply can also cause premature wear of the spark plug gap through the electrode combustion zone, thereby increasing the spark plug gap size and increasing overall wear of the ignition system. Moreover, in conditions of low engine speed and load, longer spark duration can have to be provided to ensure ignition, which can again require high current flow through the ignition coil to obtain higher dwell, resulting in increased wear of the ignition system. SUMMARY

[0004] The inventors herein have recognized potential problems with the above approach and provide a method for controlling an ignition system by which the service life of a spark plug can be increased and ignition system wear can be reduced. As one example, the required dwell (e.g., the required current supplied to the ignition coil) can be a function of the spark plug gap size, where a relatively new spark plug with a smaller gap size can require less current to break down the relatively smaller spark plug gap at a given engine speed / load than a life-terminated spark plug with a relatively larger gap size. If not adjusted to accommodate the changes in spark plug service life and gap size seen over time, selecting the dwell time based on engine operating conditions can have a negative impact on power output and engine performance. In view of these problems, it can be desirable to improve the control of the dwell time in proportion to the spark plug service life and spark plug gap size so that ignition system wear can be reduced.

[0005] In one example, the above problems can be addressed by a method for an internal combustion engine, the method comprising: adjusting a spark plug dwell based on engine operating conditions, and further adjusting the spark plug dwell in proportion to an existing spark plug condition to derive an adjusted spark plug dwell time that controls the supply of current to an ignition coil. In this way, at a given time, the dwell time can be calibrated according to engine operating conditions and can be further calibrated in proportion to the spark plug service life and spark plug gap size. As one example, a scalar factor is applied to a baseline dwell time based on both engine load / speed and spark plug gap size to produce an increased dwell time when the spark plug service life / gap size is high and the engine speed / load is high, or when the spark plug service life / gap size is low and the engine speed / load is low.

[0006] The present disclosure can provide several advantages. By adjusting the dwell time in response to engine speed and load, premature wear of the spark plug can be effectively reduced and the life of the spark plug can be extended. Additionally, by further adjusting the dwell time in proportion to the spark plug service life and spark plug gap size, overall electrical energy consumption can be reduced, thereby reducing the heating and aging of the ignition coil, which in turn reduces component stress, wear rate, and extends the service life of the ignition system components. A worn spark plug typically results in the creation of deposits on the spark electrodes, which is referred to as spark plug fouling. Spark plug fouling can prevent the spark from breaking down the gap between the spark electrodes to occur. By slowing the wear rate of the spark plug through the adjustment of the dwell, spark plug fouling can also be prevented. In this way, overall wear of the ignition system and its components can be prevented.

[0007] It is to be understood that the above overview is provided for purposes of introducing some concepts in a simplified form, which are further described below in the detailed description. This is not intended to identify key or essential features of the claimed subject matter, the scope of which is defined exclusively by the appended claims, alone. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a schematic diagram of an engine.

[0009] Figure 2 shows a detailed diagram of an example ignition system.

[0010] Figure 3 shows a flowchart illustrating a method for adjusting a dwell time.

[0011] Figure 4 shows a waveform illustrating a change in an engine operating parameter over time based on a spark plug condition. DETAILED DESCRIPTION

[0012] The following description relates to systems and methods for controlling a dwell time in an ignition system of an internal combustion engine, such as Figure 1 Optimal engine performance can be achieved by providing high pressure spark energy in an ignition system, such as the one shown in Figure 2 to achieve higher dwell when the engine is operating in high speed and high load conditions, and by increasing the spark duration to provide longer spark duration for engines operating in low speed and low load conditions. The baseline dwell amount provided can be obtained from a basic dwell lookup table included in a control module of the vehicle. The baseline dwell time can be additionally calibrated to be proportional to a spark plug condition, for example, a service life and a gap size between the spark plug electrodes. The spark plug gap size can be calculated based on accumulated mileage information, electrode material, and geometry of the spark plug assembled in the ignition system. Based on the calculated spark plug gap size, an adjusted dwell time can be calculated. To derive the adjusted dwell time for optimal spark plug ignition, a scalar, for example, based on at least the calculated spark plug gap size, can be calculated, which when multiplied by the baseline or current running dwell time will result in the adjusted dwell time.

[0013] The controller can be configured to execute a dwell adjustment procedure, such as Figure 3The example program (showing the example) applies a scalar factor to the baseline residence time based on both engine load / speed and spark plug gap size. A smaller gap size can produce a more reliable spark, but may be more prone to producing a weak spark when using the baseline residence time. Therefore, a smaller gap size can benefit from increased energy (e.g., increased residence time) at low loads when fuel may be more difficult to ignite. However, at high loads, when fuel is easily ignited, energy can be saved by reducing the voltage applied to produce a spark. In contrast, a larger gap size can produce a stronger spark, but may be more difficult to produce (e.g., due to the increased width the spark has to travel). Therefore, a larger gap size can benefit more from increased voltage (e.g., increased residence time) at high loads to ensure a spark, compared to a smaller gap size. However, the intense spark produced by spark plugs with a large gap size allows for a shorter residence time compared to spark plugs with a small gap size, which may require a longer spark duration due to the difficulty in ignition conditions compared to the combustibility requirements of the large gap size. Therefore, for engines equipped with new spark plugs with a relatively small gap size (e.g., compared to older spark plugs with a relatively large gap size), a first, larger scalar factor can be applied to increase residence time during engine idling and / or low-speed and low-load conditions. Then, as the spark plugs age and the spark plug gap increases, a second, smaller scalar factor (e.g., less than the first scalar factor) can be applied to reduce residence time to match the reduced energy demand due to the increased spark plug gap size. In another example, for an engine equipped with new spark plugs that include a relatively small gap size (e.g., compared to older spark plugs with a relatively large gap size), a third, smaller scalar factor can be applied to reduce residence during high engine speeds and load conditions. Then, as the spark plugs age and the spark plug gap increases, a fourth, larger scalar factor (greater than the third scalar factor) can be applied to obtain more residence to match the increased spark energy requirements. In this way, engine power output can be maximized while preventing premature wear of ignition system components.

[0014] Go to Figure 1A schematic diagram of one cylinder of a multi-cylinder internal combustion engine 10 of vehicle system 5 is shown. Engine 10 may also be referred to herein as engine system 10. Engine 10 may be at least partially controlled by a control system including controller 12 and by input from vehicle operator 130 via input device 132. In this example, input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. Cylinder 14 of engine 10 (also referred to herein as combustion chamber 14) may include a piston 138 positioned therein on combustion chamber wall 136. Piston 138 may be coupled to crankshaft 140 such that the reciprocating motion of the piston is converted into rotational motion of the crankshaft. Crankshaft 140 may be coupled to at least one drive wheel of the passenger vehicle via a transmission system (not shown). Additionally, a starter motor (not shown) may be coupled to crankshaft 140 via flywheel (not shown) to enable starting operation of engine 10.

[0015] Cylinder 14 can receive intake air via a series of intake passages 142, 144, and 146. Intake passages 142, 144, and 146 can also communicate with other cylinders of the engine 10 besides cylinder 14. In some examples, one or more of the intake passages may include a booster device (such as a turbocharger or supercharger). For example, Figure 1 An engine 10 equipped with a turbocharger is shown, the turbocharger including a compressor 174 disposed between an intake passage 142 and an intake passage 144, and an exhaust turbine 176 disposed along an exhaust passage 158.

[0016] The intake passage 146 may include a common intake manifold supplying air to all cylinders of the engine 10. Therefore, the intake passage 146 may also be referred to herein as the intake manifold 146. Thus, the engine intake system may include a single common intake passage in the portion of the intake system that includes the intake passage 146. In this way, the intake manifold 146 can supply air to all cylinders of the engine 10. In some examples, the engine 10 may include a separate intake passage for each cylinder of the engine 10, and therefore the number of intake passages included in the engine 10 may be equal to the number of cylinders of the engine 10.

[0017] The exhaust turbine 176 can at least partially power the compressor 174 via shaft 180, wherein the booster is configured as a turbocharger. However, in other examples, such as when the engine 10 is equipped with a supercharger, the exhaust turbine 176 can optionally be omitted, wherein mechanical input from a motor or engine can power the compressor 174. A throttle valve 162, including a throttle plate 164, can be provided along the engine's intake passage to change the flow rate and / or pressure of the intake air supplied to the engine cylinders. For example, as... Figure 1As shown, the throttle valve 162 can be positioned downstream of the compressor 174, or alternatively, it can be positioned upstream of the compressor 174.

[0018] In addition to cylinder 14, exhaust manifold 148 is also capable of receiving exhaust gas from other cylinders of engine 10. Exhaust sensor 128 is shown as an exhaust passage 158 coupled upstream of emission control device 178. For example, sensor 128 can be selected from various suitable sensors for providing exhaust air-fuel ratio indication, such as a linear oxygen sensor or UEGO (universal or wide-range exhaust oxygen sensor), a dual-state oxygen sensor or EGO (as depicted), HEGO (heated EGO), NOx, HC, or CO sensor. Emission control device 178 can be a three-way catalytic converter (TWC), a NOx trap, various other emission control devices, or combinations thereof.

[0019] Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 14 is shown to include at least one intake lift valve 150 and at least one exhaust lift valve 156 located in the upper region of cylinder 14. In some examples, each cylinder of engine 10 (including cylinder 14) may include at least two intake lift valves and at least two exhaust lift valves located in the upper region of that cylinder.

[0020] The controller 12 can control the intake valve 150 via actuator 152. Similarly, the controller 12 can control the exhaust valve 156 via actuator 154. In some cases, the controller 12 can change the signals provided to actuators 152 and 154 to control the opening and closing of the corresponding intake and exhaust valves. The positions of the intake valve 150 and exhaust valve 156 can be determined by the corresponding valve position sensors (not shown). The valve actuators can be electric valve actuated, cam actuated, or a combination thereof. Intake valve timing and exhaust valve timing can be controlled simultaneously, or any of the following possibilities can be used: variable intake cam timing, variable exhaust cam timing, dual independent variable cam timing, or fixed cam timing. Each cam actuation system can include one or more cams and can utilize one or more of a cam profile change (CPS) system, variable cam timing (VCT) system, variable valve timing (VVT) system, and / or variable valve lift (VVL) system operated by the controller 12 to change valve operation. For example, cylinder 14 may alternatively include an intake valve controlled by electric valve actuation and an exhaust valve controlled by cam actuation including CPS and / or VCT. In other examples, the intake and exhaust valves may be controlled by a common valve actuator or actuation system, or a variable valve timing actuator or actuation system.

[0021] In some examples, each cylinder of engine 10 may include a spark plug 192 for initiating combustion. In selected operating mode, ignition system 190 may, in response to a spark advance signal SA from controller 12, deliver an ignition spark to combustion chamber 14 via spark plug 192. (See below for reference...) Figure 2 An example configuration of the ignition system 190 and spark plug 192 is described.

[0022] In some examples, each cylinder of engine 10 may be configured with one or more fuel injectors for supplying fuel thereto. As a non-limiting example, cylinder 14 is shown including fuel injectors 166 and 170. However, in other examples, engine 10 may include only one of fuel injectors 166 and 170 and may not include the other. Fuel injectors 166 and 170 may be configured to deliver fuel received from fuel system 8. Fuel system 8 may include one or more fuel tanks, fuel pumps, and fuel rails. Fuel system 8 may include one or more fuels, such as propane, butane, gasoline, diesel, biofuels, etc.

[0023] Fuel injector 166 is shown directly coupled to cylinder 14 to inject fuel directly into the cylinder in proportion to the pulse width of signal FPW-1 received from controller 12 via electronic actuator 168. In this manner, fuel injector 166 provides so-called direct fuel injection (hereinafter referred to as "DI") into combustion cylinder 14. Therefore, fuel injector 166 may also be referred to herein as DI fuel injector 166. When injecting liquefied petroleum gas (LPG), fuel injector 166 can operate as a low-pressure direct injector (LPDI). Thus, fuel injector 166 can inject LPG into cylinder 14 at a relatively low cylinder pressure compared to, for example, the cylinder pressure when injecting gasoline fuel. Figure 1In one example, injector 166 is shown positioned on top of cylinder 14 and piston 138, between spark plug 192 and intake valve 150. This position can improve mixing and combustion when the engine is operated with alcohol-based fuels due to the lower volatility of some alcohol-based fuels. However, in another example, injector 166 may alternatively be located on the side of cylinder 14. In yet another example, injector 166 may be located on top of the intake valve, closer to the intake valve, to improve mixing. Fuel can be delivered from the fuel tank of fuel system 8 to fuel injector 166 via a fuel pump and fuel rails. Additionally, the fuel tank may have a pressure transducer that provides a signal to controller 12. In some examples, the fuel supplied to DI fuel injector 166 may be pressurized only by a booster pump of fuel system 8 instead of by a higher-pressure direct injection pump. However, in other examples, such as when the fuel system 8 does not supply LPG to the fuel injector 166, the fuel supplied to the injector 166 can be pressurized by both a booster pump and a higher-pressure direct injection pump.

[0024] Fuel injector 170 may be positioned in intake manifold 146, where the engine intake system includes a single common passage supplying airflow to all cylinders of engine 10. In such examples, fuel injector 170 may deliver fuel to common intake manifold 146 in a system commonly referred to as central fuel injection (CFI). Therefore, fuel injector 170 may also be referred to herein as CFI fuel injector 170. Thus, fuel injected by fuel injector 170 may be delivered to any one or more cylinders of engine 10. In some examples, intake manifold 146 may include only one CFI fuel injector 170 to deliver CFI. However, intake manifold 146 may include more than one CFI fuel injector 170. In some examples, engine 10 may include either CFI injectors or port fuel injection (PFI) injectors. Therefore, although both CFI injectors and DI injectors are present... Figure 1 The example shown is for reference only, but it should be recognized that engine 10 may include only one of the two types of injectors.

[0025] Fuel injector 170 can inject fuel received from fuel system 8 or from fuel rail of direct injector 166 via electronic actuator 171 in proportion to the pulse width of signal FPW-2 received from controller 12. Fuel injector 170 can receive LPG that has already evaporated and become gaseous. Therefore, fuel injector 170 can inject gaseous LPG. Note that a single electronic actuator 168 or 171 can be used for all fuel injection systems, or multiple actuators (e.g., each of electronic actuators 168 and 171) can be used to inject fuel. For example, as Figure 1As depicted, electronic actuator 168 can be used in fuel injector 166, and electronic actuator 171 can be used in fuel injector 170.

[0026] In an alternative example, one or more of fuel injectors 166 and 170 may be configured as direct fuel injectors for injecting fuel directly into cylinder 14. In another example, one or more of fuel injectors 166 and 170 may be configured as port fuel injectors for injecting fuel upstream of intake valve 150. In still other examples, cylinder 14 may include only a single fuel injector configured to receive different relative amounts of different fuels as a fuel mixture from the fuel system, and further configured to either inject this fuel mixture directly into the cylinder as a direct fuel injector or inject this fuel mixture upstream of the intake valve as a port fuel injector. Therefore, it should be understood that the fuel system described herein should not be limited to the specific fuel injector configurations described herein by way of example.

[0027] Fuel can be delivered to cylinder 14 via one or more of injectors 166 and 170 during a single cycle of cylinder 14. For example, each injector can deliver a portion of the total fuel injected for combustion in cylinder 14. Furthermore, the distribution and / or relative amount of fuel delivered from each injector can vary with operating conditions such as those described below herein (e.g., engine load, knock, and exhaust temperature). Intake port injected fuel can be delivered during open intake valve events, closed intake valve events (e.g., substantially before the intake stroke), and during both open and closed intake valve operations. Similarly, direct injected fuel can be delivered, for example, during the intake stroke and partly during the preceding exhaust stroke, and during the intake stroke and partly during the compression stroke. Thus, even for a single combustion event, the injected fuel can be injected at different timings from the intake port injectors and the direct injectors. Additionally, for a single combustion event, multiple injections can be performed on the delivered fuel in each cycle. Multiple injections can be performed during the compression stroke, the intake stroke, or any suitable combination thereof.

[0028] In some examples, injectors 166 and 170 may inject only a single type of fuel, such as LPG (e.g., liquid or gaseous). However, in other examples, depending on engine operating conditions, injectors 166 and 170 may inject different types or phases of fuel (e.g., gaseous and / or vaporous). For example, injectors 166 and 170 may alternate between injecting a first fuel type (e.g., gaseous LPG) and injecting a second fuel type (e.g., liquid LPG). In such examples, injectors 166 and 170 may inject only one type of fuel in each injection cycle. However, in other examples, injectors 166 and 170 may inject multiple types of fuel in a given injection cycle. Injector 166 may inject the same type of fuel as injector 170 in a given injection cycle. However, in other examples, injector 166 may inject a different type of fuel than injector 170 in a given injection cycle. For example, injector 166 may inject liquid LPG, while injector 170 may inject gaseous LPG.

[0029] As mentioned above, Figure 1 Only one cylinder of a multi-cylinder engine is shown. Thus, each cylinder can similarly include its own set of intake / exhaust valves, one or more fuel injectors, spark plugs, etc. It should be appreciated that engine 10 can include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Furthermore, each of these cylinders can include a reference cylinder 14. Figure 1 Some or all of the various components described and depicted.

[0030] Fuel injectors 166 and 170 can have different characteristics. These include size differences; for example, one injector may have a larger injection orifice than the other. Other differences include, but are not limited to, different spray angles, different operating temperatures, different target selections, different injection timings, different spray characteristics, and different positions. Furthermore, different effects can be achieved depending on the fuel distribution ratio injected in injectors 166 and 170.

[0031] Controller 12 in Figure 1The controller 12, shown as a microcomputer, includes a microprocessor unit (CPU) 106, input / output ports (I / O) 108, electronic storage media for executable programs and calibration values ​​(shown in this particular example as a non-transitory read-only memory chip (ROM) 110 for storing executable instructions), random access memory (RAM) 112, keep-alive memory (KAM) 114, and a data bus. The controller 12 can receive various signals from sensors coupled to the engine 10, including, in addition to those previously discussed: a measurement of intake mass airflow (MAF) from mass airflow sensor 122; engine coolant temperature (ECT) from temperature sensor 116 coupled to cooling manifold 118; a surface ignition sensing signal (PIP) from Hall effect sensor 120 (or other type) coupled to crankshaft 140; throttle position (TP) from throttle position sensor; and an absolute manifold pressure signal (MAP) from sensor 124. The controller 12 can generate an engine speed signal (RPM) from the PIP signal. The manifold pressure signal MAP from the manifold pressure sensor can be used to provide an indication of vacuum or pressure in the intake manifold. Controller 12 can employ... Figure 1 Various actuators adjust engine operation based on signals received from the aforementioned sensors and instructions stored in the controller's memory (e.g., non-transitory read-only memory chip 110, random access memory 112, and / or keep-alive memory 114).

[0032] In some examples, vehicle 5 may be a hybrid vehicle having multiple torque sources available for one or more wheels 55. In other examples, vehicle 5 may be a conventional vehicle with only an engine, or an electric vehicle with only one or more electric motors. In the example shown, vehicle 5 includes an engine 10 and an electric motor 52. The electric motor 52 may be a motor or a motor / generator. When one or more clutches 56 are engaged, the crankshaft 140 of engine 10 and the electric motor 52 are connected to the wheels 55 via a transmission 54. In the depicted example, a first clutch 56 is disposed between the crankshaft 140 and the electric motor 52, and a second clutch 56 is disposed between the electric motor 52 and the transmission 54. Controller 12 may send signals to the actuators of each clutch 56 to engage or disengage the clutch, thereby connecting or disconnecting the crankshaft 140 from the electric motor 52 and its connected components, and / or connecting or disconnecting the electric motor 52 from the transmission 54 and its connected components. The transmission 54 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain may be configured in various ways, including as a parallel, series, or series-parallel hybrid vehicle.

[0033] Motor 52 receives power from traction battery 58 to provide torque to wheel 55. Motor 52 can also operate as a generator to provide power, for example, during braking operations, to charge battery 58.

[0034] Figure 2 A detailed diagram of an ignition system 200 is shown, which may be... Figure 1 An example of the ignition system 190 and / or otherwise includes it in the engine of a vehicle. Herein, the ignition coil 202 may be a power transformer configured to provide a high-voltage output to a connected spark plug 204 downstream of the ignition coil. The ignition coil 202 may be parked and ignited in response to a coded park command 210 provided by the ECU 211 to the primary winding 216 of the ignition coil. The ECU 211 may be... Figure 1 An example of ECU 12. In one example, when the piston is at top dead center, a coded dwell command can be provided to ignite the ignition coil for each compression stroke of the combustion cylinder. For example, when current flows through the primary winding 216, the ignition coil 202 dwells, thereby generating a magnetic field. Ignition of the ignition coil 202 due to the termination or interruption of the current flowing through the primary winding 216 causes the magnetic field to collapse and a high-voltage pulse across the secondary winding 218 of the ignition coil 202 to provide energy to the spark plug 204.

[0035] The positive input of the primary winding 216 of the ignition coil 202 is connected to the ignition voltage source (in Figure 2 (Indicated as +Vign). In one example, +Vign can be a battery power source, where the full battery voltage can be directed to the ignition coil, or the full battery voltage sent to the ignition coil can be passed through a resistor to gradually reduce the voltage and protect the coil from premature wear. In other examples, +Vign can be another suitable power source. The current through the ignition coil 202 can be controlled using the coded dwell command 210, thereby controlling both the dwell time of the ignition coil and the ignition.

[0036] like Figure 2 As shown, the encoded dwell command 210 and +Vign can be communicatively connected to the decoder 208. The decoder 208 can also be communicatively connected to a solid-state device (such as transistor 206 or other switching mechanism) for conducting and collapsing current into the primary winding of the ignition coil 202 based on the encoded dwell command 210. The decoder 208 and transistor 206 may include a smart driver for controlling the dwell time of the ignition coil and may include interpretive logic for decoding the dwell command provided for controlling the ignition coil.

[0037] Decoder 208 may include processor 212 communicatively connected to memory device 214. The processor may be configured to execute computer- and / or machine-readable non-transitory instructions (e.g., interpreted logic) stored in the decoder's memory. In one example, the instructions may include working operations of the decoder and transistors to perform decoding and control of dwell in the ignition coil as described above. For example, decoder 208 may include instructions for evaluating an encoded dwell command to determine whether to command an adjustment of the current from +Vign to ignition coil 202. Herein, the decoder may be configured to determine a change in the encoded dwell command (e.g., an increase or decrease in dwell from a previously encoded dwell command) in response to an estimated change in engine operating parameters (e.g., engine speed, engine load, and / or other parameters). In response to detecting a change in the encoded dwell command, decoder 208 may wait for a predetermined amount of time after which an adjustment of the dwell may be made.

[0038] Upon the expiration of a predetermined time period or after determining a change in the encoded dwell command, decoder 208 may determine the dwell adjustment to be performed. Specifically, if the encoded dwell command includes an increase in dwell time, decoder 208 may initiate and / or increase the current to the ignition coil by connecting transistor 206 to a high voltage source (+Vign) for an extended dwell time, so as to conduct a higher current to the primary ignition coil relative to the previous current supplied to the primary ignition coil. In one example, the decoder may include a switching element (e.g., a resistor, not shown) that controls the connection between the transistor and the voltage source. Alternatively, if the encoded dwell command includes a decrease in dwell time, decoder 208 may decrease and / or interrupt or terminate the current to the ignition coil by disconnecting transistor 206 from the voltage source +Vign. ​​In some examples, transistor 206 may be an insulated-gate bipolar transistor (IGBT), which exhibits enhanced efficiency and switching compared to other transistor configurations. As described herein, the decoder may include logic units in which instructions and operators for decoding the encoded signal are formed.

[0039] Figure 3 The illustration shows instructions for use with ignition systems (such as...) Figure 2 A flowchart of method 300 for adjusting dwell time in cooperation with the ignition system configuration. This is based on instructions stored in the controller's memory and in conjunction with various sensors from the engine system (such as those mentioned above). Figure 1 The signal received by the sensor described, and the controller (such as) Figure 1 and Figure 2 The controller 12) can execute instructions for performing method 300. The processor (e.g., Figure 2The decoder 208 and the processor 212 Figure 1 ECU 12 and / or Figure 2 The ECU 211 can execute instructions for method 300 to actuate the switching mechanism (e.g., Figure 2 Transistor 206) for use in controlling the ignition coil (e.g., Figure 2 The operation of the ignition coil 202) thereby affects the spark plug (e.g., Figure 2 A spark is generated at the spark plug 204. At 302, method 300 includes estimating engine operating conditions. For example, these engine operating conditions may include engine speed, engine load, boost level, engine temperature, exhaust temperature, atmospheric pressure, fuel composition, particulate filter load, etc. Estimating engine and transmission (final gear ratio) operating conditions may additionally include determining mileage that can accumulate over time and be stored in the memory of controller 12. At 304, the method may include outputting a first dwell time derived from the estimated engine operating conditions from a basic dwell table. In one example, the dwell time may be empirically determined and stored in a predetermined lookup table or function. The controller may determine the first dwell time based on a lookup table (such as a basic dwell table), where the inputs are relative engine load and engine speed, and the output is the dwell time. Furthermore, the table may output the duration for which current can be conducted through the ignition coil to obtain the desired output switching current (e.g., where the switching current is the amount and / or duration of current supplied to the ignition coil). Such a table may be stored in the controller's memory for use in looking up the dwell output when determining engine speed and load. As another example, the controller can make logical determinations based on logical rules (e.g., based on current engine speed and load information obtained from speed and load sensors), said logical rules being a function of estimated engine operating conditions. The controller can then generate control signals based on these logical determinations and send these control signals to mechanisms such as switching mechanisms (e.g., ...). Figure 2 The actuator of transistor 206 is used to control the ignition of the spark plug via the ignition coil.

[0040] At 306, method 300 includes determining whether engine speed and load exceed predetermined thresholds. The thresholds mentioned at 306 may be engine speed and / or load thresholds that, when deviating from said engine speed and / or load thresholds, may cause the engine system to be in a state where it can benefit from adjusting the dwell time in the ignition system 200 based on spark plug age and spark plug gap size (e.g., by reducing spark plug wear and / or increasing the efficiency of spark generation via the spark plugs). The thresholds mentioned at 306 may also be at least one non-zero positive threshold. For example, the thresholds mentioned at 306 may include a non-zero positive speed threshold and a non-zero positive load threshold (e.g., which may be values ​​different from the speed threshold). When the vehicle is operated above either or both of the speed threshold and load threshold, fuel is more difficult to ignite than when it is operated below either or both of the speed threshold and load threshold. In some examples, the load may be evaluated at 306 only relative to the threshold, while in other examples, the speed may be evaluated at 306 only relative to the threshold. In some other examples, at 306 the rotational speed for a given load can be evaluated relative to a threshold, or at 306 the load for a given rotational speed can be evaluated relative to a threshold.

[0041] If it is determined at 306 that the engine speed and / or load are greater than a threshold, the method proceeds to 308 to further determine whether the spark plug age and / or spark plug gap size exceed a threshold. The threshold mentioned at 308 may correspond to an associated threshold for spark plug age and / or spark plug gap size, at which a basic dwell time from the lookup table described at 304 can be used (e.g., where there is no or minimal impact on spark plug aging and / or ignition efficiency due to dwell timing adjustments). The threshold described at 308 can be derived from and / or equal to the spark plug age and / or gap size used to derive the basic dwell time from the table described at 304 (e.g., worst-case scenario) and may be a non-zero positive threshold. In one example, spark plug age may be related to the gap size between spark plug electrodes, where, firstly, a new spark plug may have a relatively smaller gap size than a second older spark plug (e.g., older than the first spark plug). In other words, as spark plugs age with use, their gap size grows wider. Furthermore, any adjustments to the dwell time in the ignition system can be made based on either or both of the spark plug lifespan and the gap size, which can tend together as described above. For example, the threshold described at 308 may include only a spark plug lifespan threshold compared to the current spark plug lifespan, or in some examples, only a spark plug gap size threshold compared to the current spark plug gap size. In other examples, the threshold described at 308 may include either a threshold spark plug lifespan or a threshold spark plug gap size for a given spark plug gap size. In still other examples, the threshold described at 308 may include both a threshold spark plug lifespan and a threshold spark plug gap size, such that in response to determining that either or both of the spark plug lifespan and the spark plug gap size are higher (or lower) than the corresponding relevant threshold, the spark plug lifespan and the gap size are determined to be higher (or lower) than the threshold.

[0042] If, at 308, under engine load and / or speed above a relevant threshold, it is determined that the spark plug age and / or gap size is greater than a relevant threshold, then method 300 moves forward to 310 to apply a scaling factor to the first dwell time (obtained at 304) to increase the dwell time and obtain an adjusted dwell time (e.g., switching current) corresponding to the increased dwell time (relative to the first dwell time). When it is determined that the spark plug age and / or gap size is greater than the relevant threshold, the dwell time can be adjusted proportionally to the spark plug condition (e.g., age and / or gap size between spark plug electrodes). For example, the gap size between spark plug electrodes can be derived based on the obtained mileage information and further based on the actual spark plug electrode material and spark plug geometry used. To enable the ignition system to operate at a selected dwell time for optimal spark plug ignition, a scalar can be calculated, which, when multiplied by the currently operating dwell time (e.g., the first / basic dwell time), will produce the adjusted dwell time as described above. In one example, a series of scalars and adjusted dwell times derived from the first dwell time can be included in a basic dwell time table or another dwell time table, and further stored in the controller's memory. For example, in addition to the basic dwell time table, an additional lookup table including scalars and adjusted dwell times can be used. After determining that the spark plug age and gap size are greater than a threshold (e.g., yes at 308), at 310, a scalar factor can be derived from the aforementioned lookup table and / or calculated, and can be applied (e.g., multiplied) with the first dwell time from 304. The scalar factor can be a large multiplication factor (e.g., greater than 1) such that, when multiplied with the first dwell time, the scalar factor can be used to increase the dwell time from the first dwell time to the adjusted dwell time based on the spark plug condition (e.g., age and / or gap size above the threshold) of the ignition system of an engine operating at speeds and / or loads greater than the threshold. However, if it is determined that the spark plug age and gap size are not greater than a relevant threshold (e.g., no at 308), then method 300 moves to 312 to apply a different scalar factor (different from the scalar factor applied at 310), which may be a smaller multiplication factor (e.g., less than 1 and / or less than the scalar factor applied at 310), such that when applied to the first dwell time, the scalar factor can be used to reduce the dwell time to obtain an adjusted dwell time shorter than the first dwell time. The adjusted dwell time obtained at 312 may be based on the spark plug condition of the engine operating at speeds and loads greater than a threshold.

[0043] Returning to reference 306, if it is determined at 306 that the engine speed and load do not exceed a threshold (e.g., no at 306, thus corresponding to low engine speed and load conditions), the method proceeds to 314 to further determine whether the spark plug age and spark plug gap size exceed the threshold. The threshold mentioned at 314 can be the same as the threshold described at 308. As previously stated, the spark plug gap size can be a function of the spark plug age, where older spark plugs may have a relatively wider gap size, while newer spark plugs may include a relatively smaller gap size than older spark plugs. Furthermore, any adjustments to the dwell time in the ignition system can be made based on both the spark plug age and gap size, which can tend together as described above. If, at 314, under engine loads and / or speeds below a threshold, it is determined that the spark plug age and / or gap size are greater than a threshold (e.g., yes at 314), then method 300 moves forward to 316 to apply a scalar factor to the first dwell time to reduce dwell time and obtain an adjusted dwell time shorter than the first dwell time. After determining that the spark plug age and gap size are greater than the threshold (e.g., yes at 314), at 316, a scalar factor from a lookup table can be applied (e.g., multiplied) to the first dwell time from 304. This scalar factor may differ from the scalar factor applied at 310 and / or 312 and may be a small multiplication factor (e.g., less than 1) such that, when multiplied with the first dwell time, it can be used to reduce the dwell time from the first dwell time to the adjusted dwell time based on the spark plug condition of the ignition system of an engine operating at below-threshold speeds and loads (e.g., above-threshold age and gap size). However, if it is determined at 314 that the spark plug age and gap size are not greater than a threshold (e.g., no at 314), then method 300 moves to 318 to obtain an adjusted dwell time by applying a scalar factor, which can be a large multiplication factor (e.g., greater than the scalar factor applied at 316 and / or greater than 1), such that when applied to the first dwell time, it can be used to increase the dwell time relative to the first / basic dwell time. The adjusted dwell time obtained at 318 can be based on the spark plug condition of the engine operating below a threshold speed and load.

[0044] At 320, method 300 includes operating the ignition system according to the adjusted dwell time (e.g., Figure 2The ignition system 200. It should be understood that, in some examples, for a given operating condition where the engine speed and / or load equals the threshold described at 306 and / or the spark plug age and gap size equals the threshold described at 308, the ignition system can operate according to a first (e.g., basic) dwell time. In some examples, when the engine speed and load and / or spark plug age and gap size are approximately equal to the corresponding relevant thresholds, the scalar factor applied to the first (e.g., basic) dwell time can be substantially 1, so in such cases, operating the ignition system according to the adjusted dwell time is substantially equivalent to operating the ignition system according to the first (e.g., basic) dwell time. Operating the ignition system according to the adjusted dwell time may include providing an encoded dwell signal to the ignition coil to cause the ignition coil to dwell and ignite at the adjusted dwell time.

[0045] At 322, method 300 determines whether a change in engine operating condition from a previously detected condition has been detected. For example, after an adjusted dwell time is output, the system may monitor the operating condition to determine whether a change in engine operating condition has occurred since the adjusted dwell time was output (e.g., an engine operating condition change exceeding an relevant threshold, where different thresholds may be used for different operating conditions). Changes in engine operating condition may include changes in engine speed, engine load, engine temperature, the composition of the fuel supplied for combustion, changes in particulate matter accumulated on the particulate filter, etc. If it is determined at 322 that the engine operating condition has not changed from a previous condition (e.g., the condition estimated at 302), the method moves to 324 to continue maintaining engine operation. Maintaining engine operation includes maintaining spark plug ignition in the ignition system based on an adjusted dwell time obtained at one of 310, 312, 316, or 318 (e.g., maintaining ignition system operation as described at 320). However, if a change in engine operating condition is detected at 322, method 300 returns to 302 to estimate the engine operating condition and adjust the dwell time accordingly.

[0046] In this way, by applying a scalar factor to adjust the dwell time based on engine load and speed, and further based on spark plug condition (such as spark plug age and gap size), a more suitable dwell level can be used for ignition compared to the dwell time derived from a basic dwell table for worst-case conditions. For engines operating at idle or low speed and load conditions, a higher dwell time can be supplied for newer spark plugs, including those with relatively small gap sizes. As time and use progress, as spark plugs age and gap sizes increase, the dwell time can be appropriately reduced, and in one example, the dwell time can be combined with a longer spark duration to ensure ignition. Alternatively, for engines operating at high speed and load conditions, a lower dwell time can be supplied for newer spark plugs, including those with relatively small gap sizes. As time and use progress, as spark plugs age and gap sizes increase, the dwell time can be appropriately increased to ensure ignition. By supplying an appropriate dwell time that is proportional to the actual spark plug gap size and / or service life, the rate of spark plug wear will be reduced, thereby reducing component degradation.

[0047] In one example, the spark plug gap size is estimated based on a predetermined incremental wear rate (gap change / mileage) and from a previously determined actual mileage change. The predetermined wear rate can also be adjusted in response to the average engine load within the mileage change since the last calculation, where the rate increases for higher average engine loads within the mileage change. Further modifications can be made based on the spark plug geometry and the electrode material of the specific spark plug for the engine / vehicle combination to calculate the instantaneous spark gap size, and thus calculate the required residence scalar to adjust the target residence time to meet engine requirements. The target residence time can be based on engine load and / or other instantaneous engine conditions of the primary operating condition. In this way, by combining wear rate-based adjustments with engine condition-based targets, a more accurate residence time can be used to control the coil current.

[0048] Factors contributing to the spark gap wear rate are functions of spark breakdown voltage, anode and cathode temperatures, ignition coil secondary spark current, and spark plug gap size. Examples include the number of spark events due to engine speed or the use of repeated sparks at idle during a combustion event to add supplemental energy beneficial to the combustion process. The increase in total energy delivered to the spark plug gap through multiple or repeated spark events can prove beneficial under light loads such as idling, while the flame core is still growing. Additional factors contributing to spark gap wear include: in one example, spark plug electrode temperature due to corrosion and oxide evaporation (oxidative wear); in another example, spark energy corrosion due to energy stored in the spark plug capacitor and discharged during the spark breakdown event; and in yet another example, spark energy corrosion due to energy induced and stored in the ignition coil during the heating phase of the spark duration.

[0049] For example:

[0050] Spark gap wear rate caused by operating conditions = (material volume loss per spark) × (spark plug electrode temperature scalar) × (spark voltage scalar) × (secondary energy scalar) = total volume loss per spark event

[0051] Several unique operating conditions can be evaluated separately and then combined. Examples may include unique maneuvers observed during rural driving versus urban driving, mountain or highway driving, or even trailer towing.

[0052] Total spark gap wear = (spark plug wear rate for operating conditions 1…n) × (number of spark events for operating conditions 1…n)

[0053] Scalars can be determined based on empirical studies or material properties.

[0054] Figure 4 The description is shown according to Figure 3The method described herein is based on waveforms illustrating the example changes in engine operating parameters over time, assuming spark plug condition. In the waveforms shown, the y-axis corresponds to parameters indicated near the relevant waveform, while each x-axis corresponds to a shared timeline, where times t1, t2, and t3 identify the times at which changes in engine operation are observed / controlled. The first curve (waveform 406) from the top shows vehicle mileage over time, which increases steadily along the timeline. The second curve (waveform 408) represents engine speed and load over time. The dashed line 402 depicts an example threshold engine load and / or speed, with deviations from which the engine can benefit from adjustments to dwell time based on spark plug condition. The third curve (waveform 410) shows spark plug lifespan and spark plug gap size over time. The dashed line 404 in the third curve depicts an example threshold spark plug gap size and / or spark plug lifespan, where dwell time can be adjusted based on the engine speed and / or load in operation, depending on whether the calculated spark plug gap size and / or lifespan is above or below this threshold. The fourth curve (waveform 412) shows the adjusted dwell time relative to a normalized basic dwell time 405 (e.g., normalized to engine speed and / or load at each point along the timeline), wherein dwell time adjustments (such as...) are used based on engine speed and / or load and further based on spark plug gap size and / or service life. Figure 3 The adjusted dwell time is adjusted using the method shown. The basic dwell time 405 can represent the basic dwell time at each time point for a given engine speed and / or load at that time depicted at waveform 408 (e.g., based on a dwell time table, as described above).

[0055] At time t0, engine operation under low speed and / or load is depicted with newer spark plugs having a smaller gap size. Therefore, the adjusted dwell time at t0 is set higher (e.g., a first high level compared to the basic dwell time associated with the corresponding engine speed and / or load) to ensure ignition occurs under engine conditions while the spark plug age and / or gap are below relevant thresholds. During the time period t0-t4, as shown in waveform 406, vehicle mileage steadily increases, which is related to the use and wear of the spark plugs in the ignition system, where waveform 410 shows newer spark plugs with a smaller gap during t0-t2 and older spark plugs with a wider gap during t2-t4. At time t1, as shown in waveform 408, engine condition changes exceeding the threshold are observed. As described above... Figure 3 As described in method 300, the controller (such as...) Figure 1 Controller 12) can be based on data from... Figure 1Communication between various sensors in engine 5 determines changes in engine operation. Specifically, (based on information from speed and load sensors) changes in engine speed and / or load can be estimated, and the controller can determine whether the estimated engine speed and load are greater than a threshold depicted by dashed line 402. If it is determined that the estimated engine speed and / or load is higher than the threshold speed and load, the engine can operate at a high engine speed and / or load, and the dwell time can be adjusted accordingly. The dwell time adjustment to be performed can also depend on the spark plug condition present at time t1. Therefore, at time t1, the controller 12 can further determine whether the spark plug gap size and / or service life in operation is greater than a threshold gap size and / or service life depicted by dashed line 404. As shown in waveform 410 during the time period t1-t2, at higher engine speeds and / or loads (e.g., waveform 408 during t1-t2), spark plug gap size and service life can be below a threshold, allowing the residence time to be adjusted to reduce residence relative to the relevant basic residence (represented by line 405), as shown in waveform 412 during t1-t2. The reduction in residence can be proportional to the spark plug condition determined during that time period.

[0056] During the time period t2-t3, the observed engine operating conditions can continue to exceed the threshold, as shown in waveform 408. As previously mentioned, the controller (such as...) Figure 1 The controller 12) can continue to monitor engine operation based on communications from various sensors of the engine. As vehicle mileage steadily increases, spark plug use and wear cause the spark plugs to become older and the corresponding gap size to become wider, creating a situation where the engine can benefit from a change in dwell time (e.g., to increase spark ignition efficiency and / or improve spark ignition reliability, as described above). As shown in waveform 412 during t2-t3, the dwell time can be adjusted accordingly to increase it relative to the relevant basic dwell time indicated at line 405, in order to match the increased gap size requirements under high engine speed and load conditions (e.g., a larger gap size may require more dwell time for ignition). The dwell time adjustment during the time period t2-t3 is based on spark plug condition, while the engine operating conditions during t2-t3 remain above threshold 402, as previously experienced during the operation period t1-t2.

[0057] At time t3, as shown in waveform 408, another change in engine operating conditions was observed. (As previously stated...) Figure 3 As described in the text, the controller (such as Figure 1 The controller 12) can be based on various sensors of the engine (such as those previously in...) Figure 3This change in engine operation is determined by the parameters described in the diagram. Specifically, a decrease in engine speed and load is observed in waveform 408 during the t3-t4 period, where the engine speed and / or load are observed to be below a threshold 402. As vehicle mileage steadily increases (shown by waveform 406), the use of the ignition system causes spark plug aging and results in a wider gap size, leading to a spark plug condition greater than the threshold gap size and service life. Thus, the dwell time can be adjusted based on the spark plug condition and under engine operating conditions below the threshold present during the t3-t4 period. Therefore, the controller can adjust the dwell time to reduce the dwell time relative to the relevant basic dwell time indicated at 405, as shown in waveform 412 during the t3-t4 period, where the reduction in dwell time can be proportional to the determined spark plug service life and gap size. When the spark plug's service life and / or gap size become closer to the "worst-case" condition that yields basic dwell time, adjustments to dwell time can be made to reduce the degree of dwell time (e.g., where the absolute value of the adjustment for a given speed / load condition during time t2-t3 can be higher than the absolute value of the adjustment for the same speed / load condition after time t4, because the spark plug condition after time t4 can be closer to the condition used to yield basic dwell time compared to time t2-t3).

[0058] In this way, dwell adjustment based on engine load and speed, and further based on spark plug condition (such as spark plug age and gap size), can provide more reliable and horizontally improved dwell control in the ignition system compared to using a base dwell predetermined and / or derived based on worst-case conditions (e.g., end-of-life spark plugs). By supplying a higher dwell to newer spark plugs with relatively small gap sizes at low engine speeds and loads, and proportionally reducing the dwell as spark plugs age and gap sizes increase, the disclosed systems and methods can improve (e.g., reduce) the rate of spark plug wear. Alternatively, by supplying a lower dwell to newer spark plugs with relatively small gap sizes at high engine speeds and loads, and proportionally increasing the dwell as spark plugs age and gap sizes increase, the disclosed systems and methods can reduce the rate of spark plug wear and ignition coil aging due to overheating. Therefore, a calibrated dwell time, adjusted based on engine operating conditions and further proportionally to the actual spark plug gap size and / or service life, can not only extend the life of ignition system components but also improve engine performance.

[0059] The technical effect of performing dwell adjustment in the ignition system in proportion to the spark plug gap size and / or service life is that it can prevent premature wear of the spark plugs and ignition coils. By adjusting the dwell output in proportion to a determined spark plug gap size and spark plug service life, and further based on engine operating conditions (such as engine speed and load), the power output from the ignition system can be improved, and thus the vehicle's power output can be improved.

[0060] A method for an engine includes: adjusting ignition coil dwell time based on engine operating conditions, and further adjusting the ignition coil dwell time proportionally to existing spark plug conditions to derive an adjusted ignition coil dwell time controlling the current supply to the ignition coil. A first example of the method includes the method in which the adjusted ignition coil dwell time is adjusted relative to a basic dwell time derived from a lookup table for the engine operating conditions. A second example of the method optionally includes the first example and further includes the method, wherein the engine operating conditions include one or more of engine speed and load, and the existing spark plug conditions include one or more of spark plug gap size and spark plug service life. A third example of the method optionally includes one or both of the first and second examples and further includes the method, wherein the engine operates at one or more of engine speed and load below an associated first threshold, while the spark plug conditions are above an associated second threshold, and wherein the adjusted ignition coil dwell time is lower than the basic dwell time for the engine operating conditions. A fourth example of the method optionally includes one or more of the first to third examples and further includes the method, wherein the engine operates at one or more of an associated first threshold speed and load, while the spark plug condition is above an associated second threshold, and wherein the adjusted ignition coil dwell time is higher than the basic dwell time for the engine condition. A fifth example of the method optionally includes one or more of the first to fourth examples and further includes the method, wherein the engine operates at one or more of an associated first threshold speed and load, while the spark plug condition is below an associated second threshold, and wherein the adjusted ignition coil dwell time is higher than the basic dwell time for the engine condition. A sixth example of the method optionally includes one or more of the first to fifth examples and further includes the method, wherein the engine operates at one or more of an associated first threshold speed and load, while the spark plug condition is below an associated second threshold, and wherein the adjusted ignition coil dwell time is lower than the basic dwell time for the engine condition.

[0061] An engine operating method includes: adjusting the ignition coil dwell of a spark plug coupled to an engine cylinder based on engine operating conditions and proportionally to a determined spark plug gap size, and applying the adjusted ignition coil dwell by controlling the current supply to the ignition coil based on the adjusted ignition coil dwell. A first example of the method includes the method, wherein the engine operating conditions include engine load. A second example of the method optionally includes the first example and further includes the method, wherein the spark plug gap size is based on vehicle mileage. A third example of the method optionally includes one or both of the first and second examples and further includes the method, wherein the spark plug gap size is also based on a wear rate and the vehicle mileage. A fourth example of the method optionally includes one or more of the first to third examples and further includes the method, wherein the wear rate is also based on an average engine load over a period of time. A fifth example of the method optionally includes one or more of the first to fourth examples and further includes the method, wherein the wear rate is also based on spark plug material. A sixth example of the method optionally includes one or more of the first to fifth examples and also includes the method, wherein the wear rate is further based on one or more of the spark breakdown voltage, anode and cathode temperatures, and ignition coil secondary spark current. A seventh example of the method optionally includes one or more of the first to sixth examples and also includes the method, wherein the wear rate is further based on the number of spark events.

[0062] This disclosure also provides a system comprising: an engine having cylinders, the cylinders having spark plugs positioned therein; and a controller having a memory having instructions stored therein and coupled to a coil of the spark plugs, the instructions including codes for: during engine loads below a threshold load, adjusting the dwell time in response to a gap size determined based on the spark plug's service life, including applying a larger multiplication factor to a base dwell time table, the base table being based on engine load to provide a resulting dwell time for higher primary current and stored energy compared to a smaller gap under a larger gap, wherein the factor decreases as the spark plug ages and grows to match the decrease in energy demand; and during loads above the threshold load, adjusting the dwell time in response to a gap size determined based on the spark plug's service life, including applying a smaller multiplication factor to the base dwell time table to provide a resulting dwell time for lower primary current and reduced stored energy compared to a smaller gap under a larger gap. A first example of the system includes the system in which the gap size is also based on vehicle mileage and the wear rate of the spark plugs. A second example of the system optionally includes the first example and also includes the system, wherein the wear rate is further based on the average engine load over a period of time. A third example of the system optionally includes one or both of the first and second examples and also includes the system, wherein the wear rate is further based on one or more of the spark breakdown voltage, anode and cathode temperatures, and ignition coil secondary spark current. A fourth example of the system optionally includes one or both or each of the first to third examples and also includes the system, wherein the wear rate is further based on the number of spark events over a period of time.

[0063] Note that the example control and estimation programs included herein can be used with various engine and / or vehicle system configurations. The control methods and programs disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by a control system including controllers combined with various sensors, actuators, and other engine hardware. The specific programs described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, etc. Therefore, the various actions, operations, and / or functions described can be executed in the order shown, in parallel, or omitted in some cases. Similarly, the processing order is not required to realize the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. Depending on the specific strategy used, one or more of the shown actions, operations, and / or functions can be repeatedly executed. Furthermore, the described actions, operations, and / or functions can be graphically represented by code encoded in the non-transitory memory of a computer-readable storage medium in an engine control system, wherein the actions are performed by executing instructions in a system including various engine hardware components combined with electronic controllers.

[0064] It should be recognized that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments are not intended to be limiting, as many variations are possible. For example, the above-described techniques can be applied to I-3, I-4, I-5, I-6, V-6, V-8, V-12, opposed 4-cylinder, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and constructions disclosed herein, as well as other features, functions, and / or properties.

[0065] The appended claims specifically point to certain combinations and sub-combinations that are considered novel and non-obvious. These claims may relate to a "one" element or a "first" element or its equivalent. These class claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or characteristics may be claimed by amending existing claims or by filing new claims in this application or related applications. These claims, whether broader, narrower, identical, or different in scope from the original claims, are considered to be included within the subject matter of this disclosure.

Claims

1. A method for an engine, the method comprising: The ignition coil dwell time is adjusted based on engine operating conditions, where the ignition coil dwell time is the period during which the ignition coil is charged; and The ignition coil dwell time is further adjusted proportionally to the existing spark plug condition to derive an adjusted ignition coil dwell time that controls the current supply to the ignition coil. During engine loads above a threshold load, the ignition coil dwell time is adjusted in response to a gap size determined based on the spark plug's service life. This includes applying a smaller multiplication factor to the base dwell time table to provide the resulting ignition coil dwell time for lower primary current and reduced stored energy at a smaller gap size compared to a larger gap size.

2. The method according to claim 1, wherein the multiplication factor decreases as the spark plug ages and the spark plug gap size increases to match the decrease in energy demand.

3. The method according to claim 1, wherein the engine operating condition includes one or more of the engine speed and load, and the existing spark plug condition includes one or more of the spark plug gap size and spark plug service life.

4. The method of claim 3, wherein the engine operates at one or more of an associated first threshold speed and load, while the spark plug condition is above an associated second threshold, and wherein the adjusted ignition coil dwell time is lower than the basic dwell time for the engine operating condition.

5. The method of claim 3, wherein the engine operates at one or more of an associated first threshold speed and load, while the spark plug condition is above an associated second threshold, and wherein the adjusted ignition coil dwell time is above a basic dwell time for the engine operating condition.

6. The method of claim 3, wherein the engine operates at one or more of an associated first threshold speed and load, while the spark plug condition is below an associated second threshold, and wherein the adjusted ignition coil dwell time is higher than the basic dwell time for the engine operating condition.

7. The method of claim 3, wherein the engine operates at one or more of an associated first threshold speed and load, while the spark plug condition is below an associated second threshold, and wherein the adjusted ignition coil dwell time is below the basic dwell time for the engine operating condition.

8. The method of claim 3, wherein the spark plug gap size is based on the wear rate and vehicle mileage.

9. The method of claim 8, wherein the wear rate is based on the spark plug material.

10. The method of claim 8, wherein the wear rate is based on the number of spark events.

11. A system for an engine, comprising: An engine having cylinders, wherein the cylinders have spark plugs positioned therein; as well as A controller having a memory containing instructions stored therein and coupled to the ignition coil of the spark plug, the instructions including codes for: During engine loads below a threshold load, in response to a gap size determined based on spark plug age, the ignition coil dwell time is adjusted by applying a larger multiplication factor to a base dwell time table to provide a resulting ignition coil dwell time for higher primary current and stored energy at smaller gap sizes than at larger gap sizes, wherein the multiplication factor decreases as the spark plugs age and the spark plug gap size increases to match the decrease in energy demand; wherein the ignition coil dwell time is the period during which the ignition coil is charged, and During engine loads above the threshold load, in response to adjusting the ignition coil dwell time based on the gap size determined according to the spark plug service life, this includes applying a smaller multiplication factor to the basic dwell time table to provide the resulting ignition coil dwell time for lower primary current and reduced stored energy at a smaller gap size compared to a larger gap size.

12. The system of claim 11, wherein the gap dimension is further based on vehicle mileage and the wear rate of the spark plug.

13. The system of claim 12, wherein the wear rate is further based on the average engine load over a period of time.

14. The system of claim 12, wherein the wear rate is further based on one or more of the spark breakdown voltage, anode and cathode temperatures, and secondary spark current of the ignition coil.

15. The system of claim 12, wherein the wear rate is further based on the number of spark events over a period of time.

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