CA1306000C - Under the flywheel ignition system - Google Patents

Abstract

AN IMPROVED UNDER THE
FLYWHEEL IGNITION SYSTEM

Abstract Of The Disclosure The present invention is directed to an improved capacitive discharge ignition system for a two cylinder internal combustion engine, such as an outboard marine engine. The system is adapted to be located beneath the flywheel of the engine and has overspeed and overheat protection. The overheat protection is of the type which is automatically deactivated after the overheat condition dissipates, but the deactivation will only occur when the operator slows the engine to a reduced speed before resuming normal operation.

Description

AN IMPROVED UNDER THE
FLYWHEEL IGNITION SYSTEM

1 The present invention generally relates to 2 capacitive discharge ignition systems, and more specif-3 ically relates to an improved capacitive discharge 4 ignition system for a two cylinder engine, such as a marine engine and particularly an outboard marine engine.
6 Ignition systems for two cylinder engines of 7 the type used in outboard marine engines that are 8 typically within the range of about 20 to about 55 9 horsepower, are capacitive discharge ignition systems.
Such systems utilize the engine ~lywheel by using magnets 11 embedded within the flywheel and which pass in magnetic 12 proximity with coils for the purposa o~ generating power 13 for operating the engine and perhaps auxiliary equipment, 14 and for triggering the ignition timing for the engine.
In the past, the various coils were located under the 16 flywheel in position to magnetically interact with the~;
17 magnets, but the ignition circuitry was located in a 18 black box that was generally mounted on the side of the 19 engine and electrical leads extended to the various coils and to the spark plugs. While such an arrangement worked 21 satisfactorily, there was always the possibility that~the 22 black box could be damaged because of its relakive ex-23 posed location, and of course the electrical leads had to 24 be connected to the coils beneath the flywheel and to~the spark plugs, and had to be positioned so that they would 26 not be exposed to damage.
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1 The space beneath the flywheel was not large, 2 and conventional coils have heretofore occupied nearly 3 all of this space. In this regard, the flywheel typical-4 ly has most of its weight located at its outer periphery, has a bridging portion extending from the periphery to 6 the hub and the hub is connected to the crankshaft of the 7 engine. The space that is available for receiving the 8 various coils is located between the periphery and the 9 hub and the interior surface of the outer periphery is generally parallel to the crankshaft and the magnets are 11 embedded in this interior surface and adapted to magneti-12 cally interact with the coils that may be mounted on an 13 armature plate or ignition plate assembly that is mounted 14 on the engine. The ignition plate assembly is capable of limited rotational movement relative to the engine block, 16 for the purpose of providing ignition timing adjustments 17 in the manner that is well known in the art.
18 As previously alluded to, the space beneath the 19 flywheel was not large, and there was generally a rela-tively large charge coil for charging the capacitor of 21 the capacitive discharge ignition system, in addition to 22 two coils for providing auxiliary power for powering 23 lighting for the boat, the charging battery and the like.
24 These coils have generally occupied approximately three quarters of the angular space beneath the flywheel, and 26 the other quarter was occupied by the trigger coil that 27 is used to provide the proper timing for the capacitive 28 discharge ignition system.
29 While this arrangement functioned quite well, it was necessary to provide the black box containing the 31 electrical circuitry for the ignition system at a loca-32 tion elsewhere on the engine and have electrical leads 33 extending from the coils to the black box and then to the 34 spark plugs, as has been described.
~ccordingly, it is an object o~ the present lL3~

1 invention to provide an improved ignition system for a 2 two cylinder engine of the foregoing typs wherein the 3 circuitry of the ignition system is packaged in a single 4 unit that can be mounted beneath the flywheel without sacrificing the desirable Eunctional features that have 6 been otherwise provided.
7 It is another ob,ect of the present invention 8 to provide such an improved ignition system that has cir~
9 cuitry that provides overheat and overspeed protection for the engine, with the vast bulk of the circuitry con-11 tained within the single unit.
12 It is still another object of the present in-13 vention to provide the trigger coil as well as a power 14 supply coil for powering the circuitry of the ignition system within the unit, except for the charging coils, 16 thereby minimizing the number of leads and external con-17 nectors that are needed for the ignition system.
18 A more detailed object of the invention is to 19 provide a uni~ue and improved core and bobbin assembly as well as the trigger and power supply coils which provide 21 the desired power characteristics for both the trigger 22 and power supply signals.
23 These and other objects and advantages will 24 become apparent upon reading the ensuing speci fication, while referring to the attached drawings, in which:
26 FIGURE 1 is a top plan view of an ignition 27 plate as~embly and illustrating the auxiliary power 28 coils, the charging coil and the unit comprising one 29 e~bodiment of the present invention;
FIG. 2 is a perspective view of the unit com-31 prising one embodiment of the present invention;
32 FIG. 3 is a top plan view of one embodiment of 33 the present invention, shown with the protective enclo-34 sure and filling material removed, and shown with a por-tion of the flywheel of the engine;

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l FIG. 4 is a side Vi2W of the structure shown in 2 FIG. 3;
3 FIG. 5 is an end view of the structure shown in 4 FIG. 3;
FIG. 6 is a graph illustrating the waveform of 6 the voltage induced in the trigger coil of the present 7 invention;
8 FIG. 7 is a graph illustrating the waveform of 9 the voltage induced in the power supply coil of the prasent invention;
11 FIG. 8 is an electrical schematic diagram of a 12 portion of the circuitry of the preferred embodiment of 13 the present invention; and, 14 FIG. 9 is an electrical schematic diagram of another portion o~ the circuitry o~ the preferred 16 embodiment of the present invention.

17 Detailed Description 18 Broadly stated, the preferred embodiment of the l9 present invention is directed to an improved capacitive discharge ignition system for a two cylinder internal 21 combustion engine, such as an outboard marine engine.
22 While the preferred embodiment is for a two cylinder 23 engine, it is not limited to a two cylinder engine, and 24 other embodiments that would be useful for engines having more than two cylinders is within the contemplation of 26 the present invention.
27 The ignition system of the present invention 28 provides overspeed and overheat protection to prevent 29 damage to the engine in the event it experiences a run-away speed condition or becomes overheated.
31 The ignition system of the present invention is 32 adapted to be contained in a modular unit that can be 33 located beneath the flywheel of the engine, and the s~s-34 tam includes a printed circuit board to which the vast ~3~

1 bulk of the electrical components are mounted. The igni-2 tion system has a power supply coil for powering the 3 ignition circuitry and a trigger coil for triggering the 4 discharge of the capacitor for producing the sparking of the spark plugs. The power supply coil and trigger coil 6 are positioned adjacent one another and are wound on a 7 common bobbin structure and utilize a single core that is 8 configured to provide the proper characteristics for the 9 respective voltages that are needed for triggering the ignition system and for providing power for operating the 11 circuitry of the ignition system.
12 The charging coil for charging the charge 13 capacitor for the system is not provided in the modular 14 unit, nor is the temperature switch for providing the overheat signal for limiting the speed of the angine if 16 it has become overheated.
17 Turning now to the drawings, an ignition plate 18 assembly, indicated generally at 10, is shown in FI~. 1, 19 and includes the ignition system unit indicated generally at 12, embodying the present invention, a charging coil 21 14 for charging the charge capacitor of the present 22 invention, and two coils 16 for providing auxiliary power 23 for lights, battery charging and the like on a boat on 24 which the ~otor may be used. The ignition system unit 12, as shown in FIGS. 1 and 2, includes a housing having 26 extensions 18 with apertures 20 therein for mounting the 27 unit 12 to the ignition plate assembly 10 with screws 22 28 or the like. The housing is preferably made of a plastic 29 or plastic-like material, such as Rynite~ made by DuPont.
After the circuitry is assembled and placed within the 31 housing, it is then filled with a potting compound, 32 preferably a polyurethane or other suitable material, to 33 seal the circuitry, protecting it from vibration, mois-34 ture and corrosive elements.
As is shown in FIGS. 2 and 3, a magnetically ~3c~

1 conductive core, indicated generally at 24, has its outer 2 end 26 axtending through the outer curved surface 28 of 3 the housing so as to be in close proximity to a flywheel 4 30 which has magnet elements 32 and 34 embedded within the interior face 36 of the flywheel. For the two cylin-6 der engine e~bodiment specifically described herein, the 7 flywheel contains two sets of magnets, one set of which 8 is shown in FIG. 3. The magnet element 32 has its front 9 face comprising a north magnetic pole, while the element 34 has a front face comprising a south magnetic pole.
11 Another set of magnetic elements is provided 12 but is not shown, and is diametrically opposite those 13 shown in FIG. 3. The second set has the poles r~versed, 14 so that during rotation of the flywheel, there is an alternation of magnetic pole transitions as the sets of 16 magnetic elements pass the core 24, so as to induce 17 opposite going voltages in the coils that are wound 18 around the core 24, as will be hereinafter described.
19 Stated in other words, if the rotation of the flywheel is as shown by the arrow 38, the illustrated magnetic 21 elements will provide a north-to-south pole transition, 22 while the other set of magnetic elements will provide a 23 south-to-ncrth pole transition. The distance bPtween the 24 core end 26 and the surface of the magnetic elements as they pass the core end 26 is preferably about 0.015 26 inches.
27 In accordance with an important aspect of the 28 present invention, the ignition system has a printed 29 circuit board 40 on which the electrical components are mounted and electrically connected. A plastic bobbin 42 31 is provided on which a power supply coil 44 for powering 32 the circuitry of the ignition system is wound, as is a 33 trigger coil 46 for triggering the ignition system. Th 34 core 24 i.s shown to comprise five laminations ak the outer end 26 and these five laminations extend to the ~306~0 1 boundary portion 48 separating the two coils 44 and 46.
2 The center lamination 50 is shortened vertically a small 3 amount, as is illustrated in FIG. 5, and extends toward a 4 hub 52 of the flywheel as shown in FIG. 3. The distance between the end of the center lamination and khe hub 52 6 is approximately 0.25 inches, which is sufficiently close 7 to complete the magnetic circuit to the hub and to the 8 crankshaft to which the flywheel is attached. The con-9 figuration of the core and its spacial relationship to the magnets in the periphery of the flywhe 1 and to the 11 hub permit a magnetic circuit to be completed from the 12 magnets, through the core, to the hub of the ~lywheel and 13 to the engine crankshaft. The arrangement is different 14 from prior cores which often completed the magnetic cir-cuit in the core itself. The arrangement disclosed here~
16 in contributes to the efficient utilization of the avail-17 able space inasmuch as the core is generally straight, 18 slender and elongated.
19 The e~fect of having five laminations of the core 24 extending through the power supply coil 44 and 21 only one lamination extending through the trigger coil 46 22 is to provide narrow trigger pulses for triggering the 23 discharge of the charge capacitor 72. This is shown in 24 the waveform of FIG. 6 by the positive pulses 54 which alternate with the negative pulses 56, only one of the 26 latter of which is shown in the drawing~ The single 27 laminate saturates sooner than the multiple laminates, 28 and produces a sharper voltage pulse during pole to pole 29 transitions. The narrow pulses are separated by smallar amplitude positive and negative maverick pulses which are 31 produced when the leading and trailing edges of each 32 magnetic element pass by the core 24. The large ampli-33 tude pulses 54 and 56 occur as a result of a transition 34 between magnetic pole elements. The trigger coil is preferably approximately 650 turns of number 38 gauge ~30t;~

1 wire. The broader width of the five laminations section 2 results in the power supply coil 44 producing broader 3 pulses 60 and 62, which produce more power ~or powering 4 the circuitry o~ the present invention.
The circuitry o~ the preferred embodiment is 6 conveniently separated into two portions, one of which is 7 shown in FIG. 8 and other shown in FIG. 9. The circuitry 8 of FIG. 8 is located on the printed circuit board 40, and 9 the circuitry of FIG. 9 is located on a smaller printed circuit board 64 that is connected to the circuit board 11 40 by 9 connections identified by the numbered (1-9) 12 sguare blocks in FIG. 8 and the numbered circles ~1-9) in 13 FIG. 9.
14 Turning now to the specific schematic circuitry illustrated in FIG. 8, the charging coil 14 has its 16 opposite ends connected across a two terminal bidirec-17 tional switching means or Sidac 64 and across a full wave 18 recti~ying bridge 66, which has its positivs terminal 19 connected to line 68 and its negative terminal connected to ground line 70. The line 68 is connected to charging 21 capacitor 72 for charging the same during operation. A
22 diode 74 is provided for damping purposes and a resistor 23 76 connected to the charging capacitor 72 via line 68 is 24 also connPcted to ground through a stop switch for turn-ing the engine on and off~ When the stop switch is 26 closed, the capacitor 72 is discharged, and the engine 27 will decelerate and stop.
28 As previously mentioned, the embodiment illus-29 trated is a two cylinder engine and has ignition coils #1 and #2~ each of which is connected to a spark plug 78.
31 The capacitor 72 is discharged through either one o~ the 32 ignition coils at the appropriate time by operation of 33 the trigger coil or sensor coil 46 in conjunction with 34 associated triggering circuitry. The trigger coil 46 has one end connected to line 80, which is connected to diode 1 82, the cathode of which is connected via a line 84 to 2 the gate of an SCR 86 and to a capacitor 88. Similarly, 3 the other end of the trigger coil 46 is connected to line 4 81, which is connected to diode 100, the cathode o~ which is connected via a line 102 to the gate of an SCR 104 and 6 to a capacitor 106. Capacitor 88 is connected by a line 7 9o to the cathode of SCR 86 and to diode 120, as well as 8 to the ignition coil ~1, while capacitor 106 is similarly 9 connected by a line 108 to diode 110, the cathode of SCR
104 and to ignition coil ~2.
11 During operation, as one or the other of the 12 magnetic pole transitions occurs during rotation of the 13 flywheel, the trigger coil 46 provides a positive voltage 14 in either line 80 or line 81, and assuming it is line 80 by way of example, current passes through diode 82 to the 16 gate of the SCR 86 to trigger it on. It th~n cond~cts 17 current from the capacitor 72 through line 68, SCR 86 and 18 line 90 to the ignition coil #1, producing a spark in the 19 associated spark plug 78. The subseguently occurring opposite magnetic transition results in a spark being 21 produced in the other spark plug. A biasing network com-22 prised of capacitor 92, resistor 94, and diodes 96 and 98 23 oparate to mask the maverick pulses previously described, 24 so that the spark is produced by either spark plug at the desired point in time.
26 To control the sp~ed of the engine in the e~ent 27 of an overspeed condition, the circuitry of FIG. ~, 28 coupled with the circuitry of FIG. 9 operate to limit the 29 speed to a lower predetermined level. While the sensing of an overspeed condition is performed by the circuitry 31 of FIG. 9, the sensed condition produces an electxical 32 signal that is used by the circuitry of FIG. 8. If an 33 overspeed condition is detected, a high voltage level is 34 applied on line 112 that is connected to a capacitor 114 and to the gate of an SCR 116, the latter of which is ~3~0~

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1 connected in series with a resistor 118 across line 68 2 and line 70. When current is applied to the gate of SCR
3 116, it is switched into conduction, which discharges the 4 charging capacitor 72, thereby inhibiting sparking of either of the spark plugs 78. As soon as the speed is 6 reduced below the critical value, the high voltage on 7 line 112 is switched low, and the SCR 116 is switched 8 open, thereby enabling normal operation~ unless and until 9 it returns to an overspeed condition.
To control the speed of the engine in the event 11 of an overheat condition, the circuitry o~ FIG. 8 and 12 FIG. 9 also cooperate to limit the speed of the engine.
13 This is also accomplished by having a high voltage on 14 line 112, which is produced when a temperature switch 122 is closed as a result of an excessive running temperature 16 for the engine 17 To produce the high voltage on line 112, the 18 circuitry of ~IG. 9 utilizes a frequency to voltage con-19 v~rter circuit, together with comparators that produce a high output voltage on line 112 that extends to the cir-21 cuitry of FIG. 8. Referring to FIG. 8, the power supply 22 coil 44 has its opposite ends connected to lines 124 and 23 126, which extend to (see FIG. 9) an unregulated diode 24 bridge comprised of diodes 128 through 134, producing an output on line 136 that is applied through capacitor 138 26 and resistor 140 to input pin 1 of an integrated circuit 27 142, which is pref~rably a frequency to voltage converter 28 circuit, model No. CS2907-D8, made by the Cherry Semicon-29 ductor Company, although other frequency to ~oltage con-verters can be used. The voltage level on line 136 has a 31 ripple that is a function of the voltage induced in the 32 power supply coil 44 and whose frequency is therefore 33 proportional to the speed of the en~ine. The capacitor 34 138 differentiates this ripple voltage and produces pulses which are applied to pin 1 of the integrated ~3~

1 circuit 142. The frequency of the pulses in the voltage 2 on pin 1 of the integrated circuit 142 is converted to an 3 analog voltage on pin 3, so that output line 144 has a 4 voltage that varies in direct proportion to the speed o~
the engine. A reference voltage is applied to pin 7 o~
6 the integrated circuit 142 by a line 146, and the circuit 7 142 compares the values of pins 3 and 7 and provides a 8 high voltage on pin 4 ancl line 148 when the voltage on 9 pin 3 exceeds that on pin 7. ~ine 148 is connected to diode 150 which is connected to line 112, and a high 11 voltage on line 112 operates to disable the ignition as 12 previously described with respect to the circuitry of 13 FIG. 8.
14 The power for the circuitry of FIG. 9 is pro-vided by the diode bridge and line 136 has a voltaye 16 level of approximately 10 volts. Line 136 is connected 17 to resistor 152 which is connected to line 154, which in 18 turn is connected to ground line 70 through the Zener 164 19 and to pin 7 of the integrated circuit 142 through resis-tor 156 and line 148. The voltage level on line 154 is 21 preferably approximately 5.6 volts. The voltage level on 22 line 146 determines the speed at which the speed limiting 23 operation occurs, and the speed at which the ignition is 24 cut out is determined, in the absence of an overheat con-dition, by the value of one of the resistors 158, 160 or 26 162 one of which is selected by use of jumpers (not 27 shown). The values of these resistors is determined to 28 provide different maximum speed conditions for different 29 sized engines that the ignition system may be installed in. Resistors 158, 160 and 162 are preferably chosen to 31 provide ignition cutout speeds of 5200 r.p.m., 5~00 32 r.p.m. and 6100 r.p.m., respectively 33 The cutout of the ignition is also provided in 34 the event of an overheat condition, and the circuitry indicatecl generally at 166 accorplishes this. 'his .

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1 circuit operates to cutout the ignition when the tempera-2 ture switch 122 (FIG. 8) closes, which pulls line 168 3 low. Line 168 is connected to the base of a transistor 4 170 via a resistor 171 and diode 173, and a low on line 168 switches transistor 170 into conduction, which then 6 switches a transistor 172 into conduction. This has the 7 effect of placing a resistor 174 in parallel with one of 8 the resistors 158, 160 or 162, which changes the refer-9 ence voltage on pin 7 of t:he integrated circuit 142 to a lower value. This resultc; in the ignition being cut out 11 at a lower speed, and is pre~erably at approximately 2500 12 r.p.m.
13 The overheat circuit 166 remains latched, in 14 the sense that transistor 172 remains in conduction, un-til the overheat switch opens and the motor is slowed to 16 a low spead of preferably approximately 700 to 900 r.p.m.
17 This occurs as a result of the operator slowing the en-18 gine speed to this lower speed and the inability of khe 19 power supply coil 44 to supply sufficient power to power the circuitry of FIG. 9. When that happens, the transis-21 tors 172 and 170 unlatch, and the engine can then be 22 controlled to increase its speed and it can exceed the 23 ~500 r.p.mO operating speed if the overheat switch 122 is 24 open. The 700 to 900 r.p.m. value for causing the cir-cuitry of FIG. 9 to cease operating is primarily a func-26 tion of the size and number of turns of the power supply 27 coil 44, which is preferably about 300 turns of number 36 28 gauge wire. Removing turns of the wire would increase 29 the speed at which the circuit would cease operating~
The 700 ko 900 r.p.m. value is above ~he 31 typical idling speed of the engine of approximately 60Q
32 r.p~m., so that the engine will still operate, and will 33 not have to be restarted. A safety benefit is also 74 obtained by khe operation of the circuit. The circuikry 3 166 remains latched and controls the speed of the engine '~ , "
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1 at not greater than 2500 r.p.m. speed even if the tem-2 perature switch 122 opens, which would occur when the 3 overheat condition has dissipated. However, if the 4 operator still has the throttle at a high speed setting, the engine will not automatically return to the high 6 speed operation. The operator must return the speed to 7 below the 700 to 900 r.p.m. speed to unlatch the circuit, 8 at which time the operator can then adjust the speed to 9 that which is desired without any "surprise".
From the ~oregoing, it should be appreciated 11 that an improved ignition system has been described which 1~ provides desireable overspeed and overheat operating 13 limits for the engine that protects the same from damage.
14 The overheat protection has the desireable feature of automatically unlatching without shutting off the engine, 16 but only when the operating speed is manually reduced to 17 a low value. The entire ignition system is comprised of 18 a relatively few number of components and is housed in a 19 small self-contained unit that is placed under the fly-wheel of the engine. This has the efPect of reducing the 21 number of electrical leads and connectors and also pro-22 vides a protected environment for the circuitry.
23 Although various embodiments of the invention 24 have been shown and described in ~ull herein, there is no intention to limit the invention to the details of such 26 embodiments. On the contrary, it is the intention that 27 the invention cover all of the various modifications, 28 alternatives, substitutions and equivalents that may fall 29 within the spirit and scope of the invention as set forth in the appended claims.
31 Various features of the present invention are 32 set forth in the following claims.

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Claims (25)

1. Claim 1. An ignition system for an internal combustion engine, such as an outboard engine for a powering a watercraft, the engine being of the type which has a rotating flywheel located above and attached to the crankshaft of the engine, the flywheel containing two magnetic means, each having opposite magnetic pole interior surfaces adjacent one another in the direction of rotation, said two magnetic means together generating at least one magnetic north-to-south transition and at least one magnetic south-to-north transition relative to a reference location during each rotation of the fly-wheel, the system comprising:
   an ignition capacitor means;
   a printed circuit board being mounted to said engine beneath and adjacent the flywheel, said printed circuit board having nearly all of said means of the system mounted and electrically connected thereto;
   means for charging said ignition capacitor means;
   an ignition capacitor discharge means connected to discharge said ignition capacitor means in response to receiving a trigger pulse applied thereto;
   trigger pulse generating means for producing trigger pulses in synchronism with the engine speed, said trigger pulse generating means being adapted to provide pulses that define a timing characteristic for discharg-ing said ignition capacitor means;
   said trigger pulse generating means comprising at least one detecting means adapted to produce trigger pulses in response to magnetic pole-to-pole transitions passing in close proximity to said detecting means during rotation of the flywheel;
   means for producing an engine operating speed signal indicative of the speed of the engine;
   
   means for disabling the ignition capacitor charging means in response to an ignition capacitor disabling signal being received: and, means for producing an ignition capacitor disabling signal in response to an engine temperature signal being produced in response to the engine tempera-ture exceeding an upper predetermined sensed level and also in response to an engine speed signal indicating an operating speed exceeding an upper predetermined level being produced.
2. Claim 2. A system as defined in claim wherein each of said detecting means comprises a sensing coil adapted to sense magnetic pole-to-pole transitions during rotation of the flywheel.
3. Claim 3. A system as defined in claim 2 further including a power supply coil located adjacent the sensing coil for generating power in response to magnetic pole-to-pole transitions during rotation of the flywheel, said power supply coil being connected to transmit the power to the system for operating the same.
4. Claim 4. A system as defined in claim 3 wherein said sensing and power supply coils are located adjacent one another and have a magnetically conductive core that extends through both of said coils.
5. Claim 5. A system as defined in claim 3 further including a bobbin means upon which each of said sensing and power supply coils are wound, said system including a magnetic core extending through both of said coils and providing a magnetic conducting path from the magnetic means to the crankshaft of the engine.
6. Claim 6. A system as defined in claim 5 wherein said power supply coil is located adjacent said sensing coil and said power supply coil is nearer said magnetic means, said core having a larger cross sectional area within said power supply coil and having a reduced cross sectional area within said sensing coil and extending from said sensing coil to a point near the crankshaft of the engine.
7. Claim 7. A system as defined in claim 6 wherein the spacing between said core and the magnetic means is approximately 0.015 inches.
8. Claim 8. A system as defined in claim 7 wherein said core comprises multiple laminations within said power supply coil and a fewer number of laminations within said sensing coil.
9. Claim 9. A system as defined in claim 8 wherein only one of the multiple laminations extends through said sensing coil.
10. Claim 10. An ignition system for an internal combustion engine, such as an outboard engine for a powering a watercraft, the engine being of the type which has a rotating flywheel located above and attached to the crankshaft of the engine, the flywheel containing at least two magnetic means, each having opposite magnetic pole interior surfaces adjacent one another in the direction of rotation, said two magnetic means together generating at least one magnetic north-to-south transi-tion and at least one magnetic south-to-north transition relative to a reference location during each rotation of the flywheel, the system comprising:
    first circuit means, comprising (a) an ignition capacitor means:
    (b) an ignition capacitor discharge means connected to discharge said ignition capacitor means in response to receiving a trigger pulse applied thereto;
    (c) trigger pulse generating means for producing trigger pulses in synchronism with the engine speed, said trigger pulse generating means being adapted to provide pulses that define a timing characteristic for discharging said ignition capacitor means;
    (d) said trigger pulse generating means comprising at least one detecting means adapted to produce trigger pulses in response to magnetic pole to pole transitions passing in close proximity to said detecting means during rotation of the flywheel;
    (e) means for producing an engine operating speed signal indicative of the speed of the engine;
    second circuit means, comprising:
    (a) means for disabling the ignition capacitor charging means in response to an, ignition capacitor disabling signal being received;
    (b) means for intermittently producing an ignition capacitor disabling signal to maintain the operating speed below a predetermined speed in response to an engine temperature signal being produced in response to the engine temperature exceeding an upper predetermined sensed level and also in response to an engine speed signal indicating an operating speed exceeding an upper predetermined level being produced;
    (c) power pulse generating means for producing pulses in response to magnetic pole to pole transitions passing in close proximity thereto during rotation of the flywheel, said power generating means providing power for operating said second circuit means;
    and, means connected to said first circuit means for charging said ignition capacitor means.
11. Claim 11. A system as defined in claim 10 further including a printed circuit board operatively connected to said engine beneath and adjacent the flywheel, said printed circuit board having said first and second circuit means mounted thereon.
12. Claim 12. A system as defined in claim 11 wherein said trigger pulse generating means and said power pulse generating means each comprising at least one coil means mounted to said printed circuit board.
13. Claim 13. A system as defined in claim 12 wherein said trigger pulse coil means and said power pulse coil means are mounted adjacent one another on said printed circuit board, the system further including a ferromagnetic core element that extends from a location closely adjacent the magnet means, through both of said coil means to a location adjacent the flywheel, said magnet means core, flywheel and crankshaft defining a magnetic circuit.
14. Claim 14. A system as defined in claim 13 wherein said power pulse coil means is located closer to said magnet means than said trigger coil means, and said core has an increased cross-sectional area from its end adjacent said magnet means through the power pulse coil means, and a reduced cross-sectional area through the trigger pulse coil means.
15. Claim 15. A system as defined in claim 13 wherein the portion of said core that extends through the power generating coil means has a cross-sectional area that is approximately five times greater than the portion of said core that extends through the trigger coil means.
16. Claim 16. A system as defined in claim 10 wherein said predetermined speed is about 2500 r.p.m.
17. Claim 17. A system as defined in claim 10 wherein said upper level is within the range of about 5200 to about 6100 r.p.m.
18. Claim 18. An ignition system for an internal combustion engine, such as an outboard engine for a powering a watercraft, the engine being of the type which has a rotating flywheel located above and attached to the crankshaft of the engine, the engine having an ignition plate assembly beneath the flywheel and containing various coil means for interacting with magnets for producing pulses for use by the ignition system, the flywheel containing at least two magnet means, each having opposite magnetic pole interior surfaces adjacent one another in the direction of rotation, said two magnet means together generating at least one magnetic north-to-south transition and at least one magnetic south-to-north transition relative to a reference location during each rotation of the flywheel, the system comprising:
    circuit means, comprising:
    (a) a printed circuit board means mounted on the ignition plate assembly of the engine;
    (b) an ignition capacitor means;
    (c) an ignition capacitor discharge means connected to discharge said ignition capacitor means in response to receiving a trigger pulse applied thereto:
    (d) trigger pulse generating means for producing trigger pulses in synchronism with the engine speed, and comprising at least one coil means adapted to produce trigger pulses in response to magnetic pole to pole transitions passing in close proximity thereto during rotation of the flywheel;
    (e) power pulse generating means for producing pulses, and comprising at least one coil means adapted to produce power pulses in response to magnetic pole to pole transitions passing in close proximity thereto during rotation of the flywheel, said power generating means providing power for operating said circuit means;
    f) said trigger pulse coil means and said power pulse coil means being mounted adjacent one another on said printed circuit board, the system further including a ferromagnetic core element that extends from a location closely adjacent the magnet means, through both of said coil means to a location adjacent the center of the flywheel; and, means connected to said circuit means for charging said ignition capacitor means.
19. Claim 19. A system as defined in claim 18 wherein said circuit means further includes supplemental circuit means, comprising:
    means for producing an engine operating speed signal indicative of the speed of the engine;
    means for disabling the ignition capacitor charging means in response to an ignition capacitor disabling signal being received: and, means for intermittently producing an ignition capacitor disabling signal for maintaining the engine within a safe operating speed level in response to an engine temperature signal being produced in response to the engine temperature exceeding an upper predetermined sensed level and also in response to an engine speed signal indicating an operating speed exceeding an upper predetermined level being produced.
20. Claim 20. A system as defined in claim 18 wherein said trigger pulse and power pulse coil means are wound on a common bobbin means adjacent one another, said bobbin means being attached to said circuit board means;
    said core being secured to said bobbin means so as to extend through both of said coil means, said core having a generally rectangular side profile and an increased cross-sectional area in the vicinity of said power coil means and a smaller cross-sectional area in the vicinity of said trigger coil means.
21. Claim 21. A system as defined in claim 19 wherein said power pulse generating means is configured to provide power for operating said supplemental circuit means when the engine is operating above a predetermined above-idle speed, and is incapable of providing suffi-cient power for operating said supplemental circuit means below said predetermined above idle-speed, thereby incapacitating said circuit means below said supplemental predetermined above-idle speed.
22. Claim 22. A system as defined in claim 21 wherein said predetermined above-idle speed is in excess of the nominal idling speed of the engine.
23. Claim 23. A system as defined in claim 22 wherein said predetermined above-idle speed is within the range of about 700 to about 900 r.p.m.
24. Claim 24. An ignition system for an internal combustion engine, such as an outboard engine for a powering a watercraft, the engine being of the type which has a rotating flywheel located above and attached to the crankshaft of the engine, the flywheel containing at least two magnetic means, each having opposite magnetic pole interior surfaces adjacent one another in the direction of rotation, said two magnetic means together generating at least one magnetic north-to-south transi-tion and at least one magnetic south-to-north transition relative to a reference location during each rotation of the flywheel, the system comprising:
    circuit means, said circuit means including:
    (a) an ignition capacitor means;
    (b) an ignition capacitor discharge means connected to discharge said ignition capacitor means in response to receiving a trigger pulse applied thereto;
    (c) trigger pulse generating means for producing trigger pulses in synchronism with the engine speed, said trigger pulse generating means being adapted to provide pulses that define a timing characteristic for discharging said ignition capacitor means (d) said trigger pulse generating means comprising at least one detecting means adapted to produce trigger pulses in response to magnetic pole to pole transitions passing in close proximity to said detecting means during rotation of the flywheel;
    (e) means for producing an engine operating speed signal indicative of the speed of the engine;
    (f) means for disabling the ignition capacitor charging means in response to an ignition capacitor disabling signal being received;
    (g) means for intermittently producing an ignition capacitor disabling signal to maintain the operating speed below a first predetermined speed in response to an engine temperature signal being produced in response to the engine temperature exceeding an upper predetermined sensed level, and also in response to an engine speed signal indicating an operating speed exceeding a second predetermined speed being produced, said disabling signal producing means remaining operative to intermittently produce said signal even subsequently of the engine temperature being reduced below said upper predetermined sensed level, until the engine is slowed below a third predetermined speed;
    (h) power pulse generating means for producing pulses in response to magnetic pole-to-pole transitions passing in close proximity thereto during rotation of the flywheel, said power pulse generating means being configured to provide power for operating said disabling signal producing means of said circuit means when the engine is operating above said third predetermined speed, and is incapable of providing sufficient power for operating said disabling signal producing means below said third predetermined speed, thereby incapacitating the same below said third predetermined speed: and, means connected to said circuit means for charging said ignition capacitor means.
25. Claim 25. A system as defined in claim 24 wherein said first predetermined speed is about 2500 r.p.m., said second predetermined speed is within the range of about 5200 to about 6100 r.p.m., and said third predetermined speed is within the range of about 700 to about 900 r.p.m.