Patent Publication Number: US-2022213859-A1

Title: Engine ignition system with multiple ignition events

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 62/842,871 filed on May 3, 2019 the entire contents of which are incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to ignition systems for light-duty internal combustion engines. 
     BACKGROUND 
     It can sometimes be difficult to start a light-duty internal combustion engine. In the first engine revolutions, a microcontroller that controls spark ignition events might not have sufficient information to know the angular position of the engine crankshaft and therefore might not provide a spark event or might not accurately provide a spark event when needed to cause combustion and starting of the engine. Further, during the initial engine revolutions, the air-fuel mixture in the engine can be more stratified than homogeneous in nature, so it may be difficult to ignite the mixture with a single spark event during each of the initial engine cycles. To provide information about the crankshaft/piston position, additional components, like a multi-tooth input for crankshaft position sensing, camshaft position sensor(s) or other components could be used but this increases the cost and complexity of the system. 
     SUMMARY 
     In at least some implementations, a method of controlling spark events in a combustion engine, includes determining a change in voltage at an input of a sensor during an engine revolution, and providing at least two spark event signals to attempt to provide at least two spark events in the engine during the engine revolution. In at least some implementations, the engine revolution is within a first threshold number of engine revolutions from attempted starting of the engine. In at least some implementations, the first threshold may include the first and up to ten engine revolutions from attempted starting of the engine. In at least some implementations, after the first threshold of engine revolutions a single spark is provided during the subsequent engine revolution. 
     In at least some implementations, a voltage induced at the input of the sensor is either positive or negative more than once per engine revolution and the spark event signals are provided on at least two occasions when the voltage becomes positive or at least two times the voltage becomes negative in a given engine revolution. The spark event signals may be provided each time the voltage becomes positive or each time the voltage becomes negative in a given engine revolution. 
     In at least some implementations, the number of spark event signals provided during an engine revolution is determined as a function of the magnitude of the voltage at the input. 
     In at least some implementations, the change in voltage is a transition from zero volts or a negative voltage to a positive value, or a transition from zero volts or a positive voltage to a negative voltage, or a transition from an increasing voltage to a decreasing voltage. 
     In at least some implementations, the sensor is a VR sensor and the change in voltage is caused by movement of a magnet relative to the VR sensor. The VR sensor may include a wire coil. The magnet may include a leading edge, a trailing edge and a third feature between the leading edge and the trailing edge, and wherein the leading edge, trailing edge and third feature produce changes in a voltage waveform at the VR sensor. The third feature may include a connector that couples the magnet to a flywheel. The leading edge may provide a voltage signal at the VR sensor when an engine piston is between 50 degrees and 10 degrees before top dead center. One of the leading edge, trailing edge and third feature may provide a voltage pulse when an engine piston is between 25 degrees and 0 degrees before top dead center. 
     In at least some implementations, the method includes determining an engine acceleration or deceleration event, and the engine revolution is at least one revolution within the acceleration or deceleration event. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of certain embodiments and best mode will be set forth with reference to the accompanying drawings, in which: 
         FIG. 1  shows an example of a capacitor discharge ignition (CDI) system for a light-duty combustion engine; 
         FIG. 2  is a schematic diagram of a circuit that may be used with the CDI system of  FIG. 1 ; and 
         FIG. 3  is a plot of certain engine operational parameters including magnetic pulses from a speed sensor and ignition pulses over four engine revolutions. 
     
    
    
     DETAILED DESCRIPTION 
     The methods and systems described herein generally relate to combustion engines that include ignition systems with microcontroller circuitry, including but not limited to light-duty combustion engines. Typically, the light-duty combustion engine is a single cylinder two-stroke or four-stroke gasoline powered internal combustion engine. A piston is slidably received for reciprocation in an engine cylinder and is connected to a crank shaft that, in turn, is attached to a fly wheel. Such engines are often paired with a capacitive discharge ignition (CDI) system that utilizes a microcontroller to supply a high voltage ignition pulse to a spark plug for igniting an air-fuel mixture in the engine combustion chamber. The term “light-duty combustion engine” broadly includes all types of non-automotive combustion engines, including two and four-stroke engines typically used to power devices such as gasoline-powered hand-held power tools, lawn and garden equipment, lawnmowers, weed trimmers, edgers, chain saws, snowblowers, personal watercraft, boats, snowmobiles, motorcycles, all-terrain-vehicles, etc. It should be appreciated that while the following description is in the context of a capacitive discharge ignition (CDI) system, the control circuit and/or the power supply sub-circuit described herein may be used with any number of different ignition systems and are not limited to the particular one shown here. In particular, the ignition system may include an inductive discharge ignition (IDI) system, the details of which may be generally known in the art. 
     With reference to  FIG. 1 , there is shown a cut-away view of an exemplary capacitive discharge ignition (CDI) system  10  that interacts with a flywheel  12  and generally includes an ignition module  14 , an ignition lead  16  for electrically coupling the ignition module to a spark plug SP (shown in  FIG. 2 ), and electrical connections  5 ,  21  for coupling the ignition module to one or more auxiliary loads, such as a carburetor solenoid valve. The flywheel  12  shown here includes a pair of magnetic poles or elements  22  located towards an outer periphery of the flywheel. Once flywheel  12  is rotating, magnetic elements  22  spin past and electromagnetically interact with the different coils or windings in ignition module  14  as the crankshaft  20  rotates. 
     Ignition module  14  can generate, store, and utilize the electrical energy that is induced by the rotating magnetic elements  22  in order to perform a variety of functions. According to one embodiment, ignition module  14  includes a lamstack  30 , a charge winding  32 , a primary winding  34  and a secondary winding  36  that together constitute a step-up transformer, a first auxiliary winding  38 , a second auxiliary winding  39 , a trigger winding  40 , an ignition module housing  42 , and a control circuit  50 . Lamstack  30  is preferably a ferromagnetic part that is comprised of a stack of flat, magnetically-permeable, laminate pieces typically made of steel or iron. The lamstack can assist in concentrating or focusing the changing magnetic flux created by the rotating magnetic elements  22  on the flywheel. According to the embodiment shown here, lamstack  30  has a generally U-shaped configuration that includes a pair of legs  60  and  62 . Leg  60  is aligned along the central axis of charge winding  32 , and leg  62  is aligned along the central axes of trigger winding  40  and the step-up transformer. The first auxiliary winding  38 , second auxiliary winding  39  and trigger winding  40  are shown on leg  60 , however, these windings or coils could be located elsewhere on the lamstack  30 . Magnetic elements  22  can be implemented as part of the same magnet or as separate magnetic components coupled together to provide a single flux path through flywheel  12 , to cite two of many possibilities. Additional magnetic elements can be added to flywheel  12  at other locations around its periphery to provide additional electromagnetic interaction with ignition module  14 . 
     Charge winding  32  generates electrical energy that can be used by ignition module  14  for a number of different purposes, including charging an ignition capacitor and powering an electronic processing device, to cite two of many examples. Charge winding  32  includes a bobbin  64  and a winding  66  and, according to one embodiment, is designed to have a relatively low inductance and a relatively low resistance, but this is not necessary. 
     Trigger winding  40  provides ignition module  14  with an engine input signal that is generally representative of the position and/or speed of the engine. According to the particular embodiment shown here, trigger winding  40  is located towards the end of lamstack leg  62  and is adjacent to the step-up transformer. It could, however, be arranged at a different location on the lamstack. For example, it is possible to arrange both the trigger and charge windings on a single leg of the lamstack, as opposed to arrangement shown here. It is also possible for trigger winding  40  to be omitted and for ignition module  14  to receive an engine input signal from charge winding  32  or some other device. 
     Step-up transformer uses a pair of closely-coupled windings  34 ,  36  to create high voltage ignition pulses that are sent to a spark plug SP via ignition lead  16 . Like the charge and trigger windings described above, the primary and secondary windings  34 ,  36  surround one of the legs of lamstack  30 , in this case leg  62 . The primary winding  34  has fewer turns of wire than the secondary winding  36 , which has more turns of finer gauge wire. The turn ratio between the primary and secondary windings, as well as other characteristics of the transformer, affect the voltage and are typically selected based on the particular application in which it is used. 
     Ignition module housing  42  is preferably made from a plastic, metal, or some other material, and is designed to surround and protect the components of ignition module  14 . The ignition module housing has several openings to allow lamstack legs  60  and  62 , ignition lead  16 , and electrical connections  5 ,  21  to protrude, and preferably are sealed so that moisture and other contaminants are prevented from damaging the ignition module. It should be appreciated that ignition system  10  is just one example of a capacitive discharge ignition (CDI) system that can utilize ignition module  14 , and that numerous other ignition systems and components, in addition to those shown here, could also be used as well. 
     Control circuit  50  may be carried within the housing  42  or within a housing remote from the flywheel and lamstack and communicated with the ignition module  14  to receive energy from the module  14  and to control, at least in part, operation of the module. For example, a control module may be located on or adjacent to a throttle body, such as is shown and described in PCT Patent Application Serial No. PCT/US2017/028913 filed Apr. 21, 2017 the disclosure of which is incorporated herein by reference in its entirety. Such a module may be responsive to a throttle valve position and/or other variables to control ignition timing, a fuel/air mixture content (such as by varying the amount of fuel or air with a valve), whether to cause an ignition event in a given engine cycle, engine speed control, among other things. The module could be located remotely from the engine and any throttle body, carburetor or other component associated with the engine, for example, in a handle, housing, cowling or other component of a vehicle or device that includes the engine. The control module may be coupled to portions of the ignition module  14  so that it can control, if desired, the energy that is induced, stored and discharged by the ignition system  10 . The term “coupled” broadly encompasses all ways in which two or more electrical components, devices, circuits, etc. can be in electrical communication with one another; this includes but is certainly not limited to, a direct electrical connection and a connection via intermediate components, devices, circuits, etc. The control circuit  50  may be provided according to the exemplary embodiment shown in  FIG. 2  where the control circuit is coupled to and interacts with charge winding  32 , primary ignition winding  34 , first auxiliary winding  38 , second auxiliary winding  39 , and trigger winding  40 . According to this particular example, the control circuit  50  includes an ignition discharge capacitor  52 , an ignition discharge switch  54 , a microcontroller  56 , a power supply sub-circuit  58 , as well as any number of other electrical elements, components, devices and/or sub-circuits that may be used with the control circuit and are known in the art (e.g., kill switches and kill switch circuitry). 
     The ignition discharge capacitor  52  acts as a main energy storage device for the ignition system  10 . According to the embodiment shown in  FIG. 2 , the ignition discharge capacitor  52  is coupled to the charge winding  32  and the ignition discharge switch  54  at a first terminal, and is coupled to the primary winding  34  at a second terminal. The ignition discharge capacitor  52  is configured to receive and store electrical energy from the charge winding  32  via diode  70  and to discharge the stored electrical energy through a path that includes the ignition discharge switch  54  and the primary winding  34 . Discharge of the electrical energy stored on the ignition discharge capacitor  52  is controlled by the state of the ignition discharge switch  54 , as is widely understood in the art. As these components are coupled to one or more coils in the ignition module  14 , these components may, if desired, be located within the ignition module on a circuit board  19  or otherwise arranged. 
     The ignition discharge switch  54  acts as a main switching device for the ignition system  10 . The ignition discharge switch  54  is coupled to the ignition discharge capacitor  52  at a first current carrying terminal, to ground at a second current carrying terminal, and to an output of the microcontroller  56  at its gate. As noted herein, the microcontroller  56  may be located remotely, if desired, which is to say not within the ignition module  14 . The ignition discharge switch  54  can be provided as a thyristor, for example, a silicon controller rectifier (SCR). An ignition trigger signal from an output of the microcontroller  56  activates the ignition discharge switch  54  so that the ignition discharge capacitor  52  can discharge its stored energy through the switch and thereby create a corresponding ignition pulse in the ignition coil. 
     The microcontroller  56  is an electronic processing device that executes electronic instructions in order to carry out functions pertaining to the operation of the light-duty combustion engine. This may include, for example, electronic instructions used to implement the methods described herein. In one example, the microcontroller  56  includes the 8-pin processor illustrated in  FIG. 2 , however, any other suitable controller, microcontroller, microprocessor and/or other electronic processing device may be used instead. Pins  1  and  8  are coupled to the power supply sub-circuit  58 , which provides the microcontroller with power that is somewhat regulated; pins  2  and  7  are coupled to trigger winding  40  and provide the microcontroller with an engine signal that is representative of the speed and/or position of the engine (e.g., position relative to top-dead-center); pins  3  and  5  are shown as being connected to a timing sub-circuit which will be described in more detail below; pin  4  is coupled to ground; and pin  6  is coupled to the gate of ignition discharge switch  54  so that the microcontroller can provide an ignition trigger signal, sometimes called a timing signal, for activating the switch. Some non-limiting examples of how microcontrollers can be implemented with ignition systems are provided in U.S. Pat. Nos. 7,546,836 and 7,448,358, the entire contents of which are hereby incorporated by reference. 
     The power supply sub-circuit  58  receives electrical energy from the charge winding  32 , stores the electrical energy, and provides the microcontroller  56  with regulated, or at least somewhat regulated, electrical power. The power supply sub-circuit  58  is coupled to the charge winding  32  at an input terminal  80  and to the microcontroller  56  at an output terminal  82  and, according to the example shown in  FIG. 2 , includes a first power supply switch  90 , a power supply capacitor  92 , a power supply zener  94 , a second power supply switch  96 , and one or more power supply resistors  98 . The power supply sub-circuit  58  is designed and configured to reduce the portion of the charge winding load that is attributable to powering the microcontroller  56 , or other electrically powered devices, like a solenoid or the like. The components of the power supply sub-circuit  58  may be located in the ignition module, the control module that is separate from the ignition module, or a combination of the two, as desired. 
     During a charging cycle, electrical energy induced in the charge winding  32  may be used to charge, drive and/or otherwise power one or more devices around the engine. For example, as the flywheel  12  rotates past the ignition module  14 , the magnetic elements  22  carried by the flywheel induce an AC voltage in the charge winding  32 . A positive component of the AC voltage may be used to charge the ignition discharge capacitor  52 , while a negative component of the AC voltage may be provided to the power supply sub-circuit  58  which then powers the microcontroller  56  with regulated DC power. The power supply sub-circuit  58  may be designed to limit or reduce the amount of electrical energy taken from the negative component of the AC voltage to a level that is still able to sufficiently power the microcontroller  56 , yet saves energy for use elsewhere in the system, for example to drive a fuel injector in an electronic fuel injection system. Another example of a device that may benefit from this energy savings is a solenoid that is coupled to the windings  38  and  39  and is used to control the air/fuel ratio being provided to the combustion chamber. The power supply sub-circuit may be constructed and arranged as shown in  FIG. 2  and as described in PCT Application Publication WO2017/015420. 
     Beginning with the positive portion of the AC voltage that is induced in the charge winding  32 , current flows through diode  70  and charges ignition discharge capacitor  52 . So long as the microcontroller  56  holds the ignition discharge switch  54  in an ‘off’ state, the current from the charge winding  32  is directed to the ignition discharge capacitor  52 . It is possible for the ignition discharge capacitor  52  to be charged throughout the entire positive portion of the AC voltage waveform, or at least for most of it. When it is time for the ignition system  10  to fire the spark plug SP (i.e., the ignition timing), the microcontroller  56  sends an ignition trigger signal to the ignition discharge switch  54  that turns the switch ‘on’ and creates a current path that includes the ignition discharge capacitor  52  and the primary ignition winding  34 . The electrical energy stored on the ignition discharge capacitor  52  rapidly discharges via the current path, which causes a surge in current through the primary ignition winding  34  and creates a fast-rising electro-magnetic field in the ignition coil. The fast-rising electro-magnetic field induces a high voltage ignition pulse in the secondary ignition winding  36  that travels to the spark plug SP and provides a combustion-initiating spark. Other sparking techniques, including flyback techniques, may be used instead. 
     Turning now to the negative component or portion of the AC voltage that is induced in the charge winding  32 , current initially flows through the first power supply switch  90  and charges power supply capacitor  92 . So long as second power supply switch  96  is turned ‘off’, there is current flow through power supply resistor  98  so that the voltage at the base of the first power supply switch  90  biases the switch in an ‘on’ state. Charging of the power supply capacitor  92  continues until a certain charge threshold is met; that is, until the accumulated charge on capacitor  92  exceeds the breakdown voltage of the power supply zener  94 . As mentioned above, zener diode  94  is preferably selected to have a certain breakdown voltage that corresponds to a desired charge level for the power supply sub-circuit  58 . Some initial testing has indicated that a breakdown voltage of approximately 6 V may be suitable in some light-duty engine applications, although other values may be used. The power supply capacitor  92  uses the accumulated charge to provide the microcontroller  56  with regulated DC power. Of course, additional circuitry like the secondary stage circuitry  86  may be employed for reducing ripples and/or further filtering, smoothing and/or otherwise regulating the DC power. 
     Once the stored charge on the power supply capacitor  92  exceeds the breakdown voltage of the power supply zener  94 , the zener diode becomes conductive in the reverse bias direction so that the voltage seen at the gate of the second power supply switch  96  increases. This turns the second power supply switch  96  ‘on’, which creates a low current path  84  that flows through resistor  98  and switch  96  and lowers the voltage at the base of the first power supply switch  90  to a point where it turns that switch ‘off’. With first power supply switch  90  deactivated or in an ‘off’ state, additional charging of the power supply capacitor  92  is prevented. Accordingly, instead of charging the power supply capacitor  92  during the entire negative portion of the AC voltage waveform, the power supply sub-circuit  58  only charges capacitor  92  for a first segment of the negative portion of the AC voltage waveform; during a second segment, the capacitor  92  is not being charged. 
     As mentioned above, the electrical energy that is saved or not used by power supply sub-circuit  58  may be applied to any number of different devices around the engine. One example of such a device is a solenoid that controls the air/fuel ratio of the gas mixture supplied from a carburetor to a combustion chamber. Referring back to  FIG. 2 , the first auxiliary winding  38  and the second auxiliary winding  39  could be coupled to a device  88 , such as a solenoid, an additional microcontroller or any other device requiring electrical energy. The first and second auxiliary windings  38  and  39  may be connected in parallel with each other and may each have one terminal coupled to the solenoid via intervening diodes  100  and  102 , respectively and their other terminals coupled to ground. A zener diode  104  may be connected in parallel between the solenoid and coils  38  and  39  to protect the solenoid from a voltage greater than the zener diode breakdown voltage (excess current flows through the zener diode to ground). 
     Because the magnet(s)  22  are fixed to the flywheel  12 , the position of the magnet(s) relative to one or more coils of the ignition circuit may be used to determine the position of the flywheel and thus, the position of the crankshaft and piston. This information may also be used to determine the engine speed (e.g. the time from a certain engine position in one revolution to the same engine position in the next revolution may be used to determine the engine speed during that revolution). Use of multiple magnets spaced about the periphery of the flywheel can enhance the resolution of this determination by providing more data points in a revolution. Engine speed may also be determined by a sensor that is responsive to the position of the flywheel. Representative sensors including magnetically responsive sensors like hall-effect sensors or variable reluctance sensors. The flywheel may have teeth and the sensors may be responsive to the passing by of one or more teeth to determine flywheel position and hence, crankshaft position. The trigger coil  40  or a different coil in the ignition module may be used as a VR sensor as noted above. 
     As shown in  FIG. 3 , when the magnet  22  passes by a VR sensor, the voltage at an input of the VR sensor is not simply a single sine wave, and instead a resulting waveform  108  includes multiple positive and negative pulses. In at least some implementations, the pulses include: 1) at least one major positive pulse  110  having a first positive magnitude; 2) at least one minor positive pulse  112  having a second positive magnitude less than the first positive magnitude; 3) at least one major negative pulse  114  having a first negative magnitude; and 4) at least one minor negative pulse  116  having a second negative magnitude less than the first negative magnitude. In the example shown, the pulse includes two minor positive pulses  112  and two minor negative pulses  116 . Thus, there are three positive pulses and three negative pulses when a magnet passes by the VR sensor. 
     In at least some implementations, and in at least some IDI systems more than one of the pulses  110 - 116  may be used to cause a spark event, or to at least attempt to generate a spark at the spark plug SP. For example, two or more of the positive pulses may be used to generate a like number of spark events, and in at least some implementations, each positive pulse may be used to provide a signal to the microcontroller  56  which in turn may initiate a spark event at the spark plug SP at least when sufficient energy may be provided by the ignition circuit. At least in the first engine revolution upon an attempted engine start, there may be sufficient energy in an IDI system while such energy might not be available until a second or third revolution in a CDI system. The microcontroller  56  may recognize or determine when the pulse moves from zero (or other base value) to a positive value (or value greater than the base), and upon such determination the microcontroller  56  may initiate a spark event. Of course, other portions of the pulse may be used by the microcontroller  56  to cause desired spark events, such as a transition from zero/base to a negative/lower voltage, or a transition from an increasing voltage to a decreasing voltage, etc., and different numbers of spark events may be provided in different engine revolutions or cycles. In at least some implementations, a voltage induced at the input of the sensor is either positive or negative more than once per engine revolution and the spark event signals are provided on at least two occasions when the voltage becomes positive or at least two times the voltage becomes negative in a given engine revolution, and spark event signals may be provided each time the voltage becomes positive or negative, if desired. 
     With multiple spark triggering points in a pulse, multiple spark events may be generated, for example, during the first one or more engine revolutions in/during an attempt to start the engine. In the first engine revolutions, the microcontroller  56  might not have sufficient information to know the angular position of the engine crankshaft  20  and therefore might not provide a spark event or might not accurately provide a spark event when needed to cause combustion and starting of the engine. Further, during the initial engine revolutions, the air-fuel mixture in the engine typically is more stratified than homogeneous in nature, so it may be beneficial to provide the several spark events during each compression portion of the initial engine cycles to optimize the potential to combust the air-fuel mixture. Thus, the likelihood of combustion in the initial engine revolutions during starting of an internal combustion engine may be improved by providing a spark multiple times during the compression portion of the engine cycle in a two or four stroke engine. Further, this may be done with existing components in the ignition system and engine and without adding cost by using an existing magnet on the flywheel and an existing coil or VR sensor. That is, the system and method of controlling the ignition does not need a multi-tooth input for crankshaft position sensing, camshaft position sensing or other methods of accurately determining crankshaft angular displacement all of which would increase the cost and complexity of the system. 
     A waveform  108  including the multiple pulses  110 - 116  over four engine cycles is shown in  FIG. 3 . The waveform may be caused by different features passing by the VR sensor (or other component that may sense the voltage or in which a voltage may be induced, for example, a wire coil as noted above) each rotation of the crankshaft  20 . For example, as shown in  FIG. 1 , the magnet  22  may include a leading edge  120  at a north or south end of the magnet, a trailing edge  122  at the other end of the magnet (i.e. if the leading edge  120  is at the north end of the magnet, then the trailing edge  122  is at the south end, or vice versa) and a third feature such as the transition between north and south poles of the magnet and/or a connector  124  that retains the magnet  22  on the flywheel  12 , like a clip or screw located between the ends of the magnet and a hole or other feature formed in the magnet for the connector. These features  120 ,  122 ,  124  may cause a waveform  108  as shown in  FIG. 3  each time the magnet  22  is moved past the VR sensor as the flywheel  12  is rotated. 
     In at least some implementations, the magnet  22  is located on the flywheel  12  in a position that enables the VR sensor signal to occur within or correspond to a range of acceptable spark timing during engine starting. For example, the leading edge  120  of the magnet  22  may provide a signal at the VR sensor when the engine piston is in the compression phase of engine operation such as between 50 degrees and 10 degrees before top dead center (BTDC), and may nominally be at approximately 30 degrees in at least some implementations. In at least some implementations, the third feature (e.g. the connector  124  between the ends  120 ,  122  of the magnet  22 ) generates a pulse between the two ends  120 ,  122  of the magnet  22 , and this middle pulse-generating feature may be located so that the pulse occurs at approximately 20 degrees BTDC, and the trailing edge  122  of the magnet  22  may be located so that the pulse associated with the trailing edge  122  occurs at approximately 10 degrees BTDC, and in at least some implementations may be between 25 degrees and −15 degrees BTDC. In at least some implementation, it may be required that one or more of the above features  120 ,  122 ,  124  be located so that the corresponding pulse occurs between 25 degrees and 0 degrees BTDC, for suitable ignition timing to start the engine. 
     The ignition system may use the voltage at an input of the VR sensor to determine crankshaft position. During the first engine revolutions, the crankshaft position might be indeterminate or inaccurate due to the following: on the first passing of the magnet  22  by the sensor, the microcontroller  56  has no previous event to use to determine the angular displacement as a function of time as the time period is infinity; and on the second passing of the magnet  22 , the calculated time unit per angular displacement unit (typically degrees Crank Angle (CA)) is often not be very accurate for the next revolution, as the engine is rapidly changing speed. Thus, in a threshold number of the initial engine revolutions upon attempted starting of the engine, the ignition events can be controlled as a function of the waveform  108  (i.e. the voltage) at the VR sensor or other magneto-voltage responsive component(s). 
     After the threshold number of engine revolutions, the microcontroller  56  can be used to provide spark events according to a normal operation program or method. A simple engine revolution counter may be used to control the hand-off between the two control methods after the threshold number of revolutions have occurred, a hardware component like a switch may be used to cause a change upon sufficient energy being developed in the system (e.g. due to increased engine speed), or the transition between method may occur in any other desired way (e.g. lapse of actual time rather than revolutions, as a function of temperature, as a function of two or more of time, revolutions and temperature, etc). 
     In line  126  in  FIG. 3 , it can be seen that during the first engine revolution, the spark control method provided two signals  128  to cause two spark events. The signals  128  may be a voltage provided from the microcontroller  56  to change the state of the ignition switch, or other voltage, as desired. The signals  128  were provided when the waveform became positive the first two times, although as noted above, other triggering events may be used. In the second engine revolution, two spark event signals  128  were provided again as the waveform became positive the first two times. In the third engine revolution, three spark event signals  128  were provided, with each signal provided each time that the waveform  108  became positive. The number of spark event signals provided during a revolution may be pre-programmed in the microcontroller&#39;s instructions or in data used by the microcontroller, or it may be determined as a function of one or more factors determined during operation, such as the magnitude of the major positive pulse  110  or a different portion of the waveform  108  (which is a function of rotational speed of the engine crankshaft  20  and attached flywheel  12 ), engine temperature, air temperature, or the like. In the example shown in  FIG. 3 , the microcontroller  56  switched to the normal spark event control method and provided a single spark event signal  128  at a time determined in the instructions of the microcontroller  56 . In at least some implementations, the first threshold is 10 engine revolutions or fewer. That is, the method may include providing multiple spark events for the first 10 engine revolutions or fewer, as desired for a particular application. After the first threshold number of engine revolutions, the system may change to a different spark event control method. 
     While described with regard to the initial engine revolutions associated with starting an engine, the system could use the multiple spark event control method during normal operation, if desired. And the system could switch to the multiple spark event control method during times when the angular displacement/position as determined by the microcontroller may be inaccurate or less accurate than desired, such as during rapid acceleration or deceleration events. The microcontroller  56  could determine the occurrence of an acceleration or deceleration event, which may be beyond a threshold (e.g. a certain RPM (revolutions per minute) change threshold), and the microcontroller  56  may switch from the normal control method to the multiple spark event control method, resulting in accurate yet fixed (e.g. tied to the waveform at the VR sensor) spark events. The spark control method to be used at any given time could be programmed or otherwise instructions stored in memory of the microcontroller, and a decision as to which control method to use may be based on rate of acceleration or deceleration, engine speed at beginning of an event, engine load, engine temperature, air temperature, etc. 
     The forms of the invention herein disclosed constitute presently preferred embodiments and many other forms and embodiments are possible. For example, while the method is described above with regard to discrete points or portions of the waveform being used as a signal that starts the process to cause a spark event, the method/system could cause or attempt to cause a spark event at any of the various points of the waveform. Or, upon initial detection of a voltage from the magnet, or a voltage beyond a threshold, or some other portion of the waveform, the method/system may provide two or more ignition events at a predetermined interval(s) after initial detection. In other words, the ignition events may occur at regular intervals after initial detection of some signal and not as a function of different portions of the waveform. Further, the circuit diagram shown in  FIG. 2  and the coil arrangement shown in  FIG. 1  are merely examples and are not intended to limit the innovations set forth herein, other circuits and coils may be used, as desired. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention. 
     As used in this specification and claims, the terms “for example,” “for instance,” “e.g.,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.