CA1099777A - Ignition system - Google Patents
Ignition systemInfo
- Publication number
- CA1099777A CA1099777A CA268,205A CA268205A CA1099777A CA 1099777 A CA1099777 A CA 1099777A CA 268205 A CA268205 A CA 268205A CA 1099777 A CA1099777 A CA 1099777A
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- CA
- Canada
- Prior art keywords
- charging
- winding
- capacitor
- primary
- polarity
- Prior art date
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- Ignition Installations For Internal Combustion Engines (AREA)
- Electrical Control Of Ignition Timing (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A means for readily changing the ignition system of an existing internal combustion engine to a solid state capacitive discharge ignition system which comprises an auxiliary coil, a primary ignition coil and a secondary ignition coil wound on a single leg of a stator. The stator is designed with one or more additional legs which complete a conductive path for the time varying flux, and adapt the stator for mounting on the existing structure of the engine.
In addition, two legs of the stator which define a flux path may each be divided into two segments at their outer extremity, one of each pair being slightly longer than the other so as to create two different size air gaps for each leg. A washer-like element may be used in cooperation with the above structure to change the position of the rotor relative to the crankshaft so as to alter the timing of the ignition system.
A means for readily changing the ignition system of an existing internal combustion engine to a solid state capacitive discharge ignition system which comprises an auxiliary coil, a primary ignition coil and a secondary ignition coil wound on a single leg of a stator. The stator is designed with one or more additional legs which complete a conductive path for the time varying flux, and adapt the stator for mounting on the existing structure of the engine.
In addition, two legs of the stator which define a flux path may each be divided into two segments at their outer extremity, one of each pair being slightly longer than the other so as to create two different size air gaps for each leg. A washer-like element may be used in cooperation with the above structure to change the position of the rotor relative to the crankshaft so as to alter the timing of the ignition system.
Description
~ ~95~ 7 This invention relates generally to ignition systems for internal combustion engines and in particular to means by which an existing combustion engine having a conventional ignition system may be provided with a capacitor discharge ignition system with minimal time and effort. This ignition system is generally of the type disclosed in applicant's Canadian Patent No.
1,~34,1~8, issued July 4, 1978.
Previously, the complex nature oP capacitive discharge ignition systems made them prohibitively expensive for application to smaller internal combustion engines presently utilizing simple magneto ignition systems. With the development of the improved system disclosed in the above referenced copending applications, the number of components, package size, complexity and cost have been reduced sufficiently to allow the incorporation of such systems into these smaller sized engines such as are used in lawnmowers, chain saws, outboard motors, and the like. The ignition system of the aforementioned patent is generally applicable for incorporation during original e~uipment~manufacture of the associated engines. The present invention provides an inexpensive ignition replacement package whereby existing conventional magneto ignition systems may be easily converted to this improved capacitive discharge system ~ by the owner of the engine subsequent to its initial purchase.; The substantial achievement of this invention can be appreciated when the nature of existing engines and their J
associated ignltion systems is considered. In order for mb~
~9~77 a conversion kit to be commercially practical, it must be adaptable for use with a variety of engine configurations.
Conventional magneto systems may have a rotor rotating either clockwise or counterclockwise. Also, the Leading magnetic pole may be either north or south seekin8 ; Further, the ignition timing of the existing ignition system may not be appropriate due to the differing response characteristics. Additionally, varying existing space limitations must be considered since a conversion would not be commercially practical if significant engine structure modifications were required. The present invention as described herein bridges wide variations in engine and existing ignition systems so as to provide a conversion kit in which a minimum of component structure variations will accommodate a large variety of engine and ignition system configurations without structural modifications.
Specifically, the present invention relates to a capacitor discharge system for an internal combustion engine comprising a permanent magnet means rotated about a circular path in synchronism with the operation of the engine, a core of ferromagnetic material mounted adjacent the circular path and having one portion providing a path for the varying flux generated by the movement of the magnet means past the core, a charging winding and a transformer core portion. The charging winding is offset from the primary and secondary windings with respect to the circular path, the charging winding and primary winding being wound on the one core portion such that the voltages mb/!, - 2 -,.. -~ .. , . . ,,.,. . . "
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induced therein by the varying flux each inclLIdes half wave voltages of opposite polarity. A charging circuit is provided including a capacitor connected across the charging winding and a diode poled to pass half wave voltages of one polarity for charging the capacitor and maintaining the capacitor charged when the voltage generated in the charging winding is opposite the one polarity. Circuit means connect the capacitor with the primary winding for discharging the capacitor through the primary winding and include an electronic switch means having anode, cathode and control electrodes, the anodecathode junction of the switch means interconnecting the ends of the charging winding and the primary winding which are simultaneously at the same polarity. The control electrode is connected to the other end of the primary winding, the polarity of which is opposite this same polarity. The switch means is nonconductive during the charging of the capacitor by this one polarity of the voltage generated in the charging coil and is rendered conductive by voltage generated in the primary winding opposite this same polarity whereby the capacitor is charged during one complete half cycle of voltage generated in the charging coil and discharged during the next half wa~e voltage generated in the charging winding.
~dditional advantages and features of the present J
invention will become apparent from the following detailed ~ description taken in conjunc~ion with the attached drawings ; and appended claims.
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BRIEF ~ESCRIPTION OF THE DRAWI~GS
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Figure 1 is a perspective view of a coil wound upon a stator having ~.wo legs with mounti.ng provisions contained thereon all in accordance with the present invention;
Figure 2 is a second embodiment of the present invention showing a stator structurs with a third leg for accommodating an existing mounting structure;
Figure 3 is a third embodiment of the present invention showlng a stator structure employing yet another mounting arrangement;
Figure 4 is a fourth embodiment of the present invention similar to that of Figure 3 but employing a different mounting structure;
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Fi~ure 5 is a sectional ~idc ~icW o~ thc c~il assembly utilized in conjunction with the co~e structurcs o~
the present invention;
Figure 6 is an edge view o a keywa~ shi~tex ~ox use ln altering the axisting timing se~uence;
Figure 7 is another view o~ the ke~w~ shi~ter of Figure 6 as viewed ~rom the direction of arrow A of ~igure 6;
Figure 8 is a sectional perspectiye view of a portion o~ a crankshaft o~ an internal combust.ion engine having a rotor mounted thereon and sho~ing a ke~ywa~ shifter installed in operatiye relation thereto;
Fi~ure 9 is a schematic dia~ram o~ the capacitiye ignition system in accordance with the present invention;
Figure 10 is a graphical plot of volta~e Vs. time showing the operating waveforms for a capacitive discharge ignitio~ system of the present inyention;
Figure 11 is yet another embodiment of the present ~nvention similar to that of Figure 2 but having split leg sections;
Figure 12 is another embodiment of the present i~Vention similar to that o~ Figure 1 but also havin~ split leg sections~thereon;
Figure 13 is yet another embodiment o~ the present inVention similar to that of ~lgure 3 but haying s~lit le~ J
6ections incorporated thexeon;
Figu~es 14 through 16 ~re o~ ~ t~piaal existing lawnmower engine with the sheet metal cowlin~ xe~oved and ~howing, in sequence,` a convention~l ignition system inst~lled , ~, :' .
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ther~on, the cngine with thc conventional ignition s~ste~ co$e ~nd coil assembl~ remov~d and the engine with ~ core ~nd coil assembly of the pres~nt invention installcd ther~on; and Pigur~s 17 through 19 are o~ a typic~l existing chain saw engine with the sheet metal cowling ~cmoved and also showing, in se~uence, the existing engine ignition ~yste~, the removal thereoE, and a core and coil of the present invention installed thereon.
DESCRIPTION OF THE PRE:FERRED EMBODIMENT
Re~erring now to Figure l, a stator 10 is shown containing a coil assembly 12 on one leq thereo~. Stator 10 has a generally rectangular cross section and is ~enerally nu" shaped having a pair o~ spaced apart substantially parallel legs 14 and 16 and an interconnecting por~ion 18 extending between and connecting one end of each of legs 14 and 16. Leg 14 has a protrusion 15 extending outward there-from and disposed approximately midway along its length.
Leg 14 also has an elongated aperture 2a adjacent pxotrusion 15 and extending along the longitudinal axis thereo~.
Interconnecting portion 18 has one side 22 which is per-pendicular to the longitudinal axis of legs 14 and 16 and a second side 24 which is bowed outward Crom side 22 so as t~ have a maximum width portion 26 at a point slightly offset toward leg 16 from its ~idpoint. Also, inte~-connecting portion 18 similarly has an elongated aperture 28 disposed adjacent portion 26 and extendin~ between sides 22 and 24 and parallel to aperture 20. ~pertures 2~ and 2B ar~ located on stator 10 so a~ to coincide with existing : ~ :: , ,: :
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mounting pads provided on an internal combustion enqine and are substantially e~ually elonyated, thus p~ovidin~ mcans by which the air gap ~etween the stator and a rot~ting magnetic fleld may be adjustea, as is described in greater detail ~elow. Legs 14 and 16 axe substantially equal in length and have respective convex end surfaces ~0 ~nd 32 thereon.
' Conventionally, the cores o~ magneto ignition systems are constructed o$ cold rolled steel. Cold rolled steel cores are used since the cold rolled steel is an excellent collector of ~lux emanatlng fro~ the permanent magnets of the rotor~ Althou~h the core material of the i,gnition systems disclosed herein c~n be' cold rolled steel, it has been discovered that electric~l steel, i.e.~ steel containing a silicone alloy as is used in transformer core constructions, provides a substantial increase ln the output voltage of the ignition system. For example/ output voltage increases of 40~ have been obtained using electrical steel.
It is believed that this substantial increase in output voltage is due to the ~act that cold rolled steel is not a desirable core material for the ignition coil so that the voltage rise upon discharging of the capacito into the primary winding of the ignition coil is hampered. The electrical s,teel is a more effective core for the ignition coil than cold xolled steel, and yet has a good capability of collecting the 1ux emanating from the permanent ma~nets o the rotor. The usual core matarials for i~nition coils are errite materials. These materials would not be satis-iactory as a core material or the ignition system since they would not be good collectors o~ the flux eman~ting ~rom the , 6- , ~
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permanont magnets o~ thc roto~ Accordinql~, stato~ 10 is preerably constructed of multiple la~inations o~ elect~ic~1 st~el secured by two rivets 34 and 36 as shown in Figure 1 or other like ~astening devices.
Leg 16 o~ stator 10 has coil assembl~ 12 surroundin~
its longitudinal midportion. Coil ~ssembly 12 com~rises auxiliary coil 38 located adj~cent convex sur~ace 32 and ignition coils 40 disposed i~mediately behind auxiliary coil 38. Coil assembly 12 will be described in greater detail belo~
Stator 10 is particularly suited ~o~ use with the Rope~ 2.5 chain saw engine i~nition syste~. In such an application, convex sur~aces 30 and 32 haye a curyature radius o~ between 1.760 and 1.764 inches and are s~metric~l about a longitudinal axis extending approximately equ~distant between legs 14 and 16. Further, in such an application, the stator structure is constructed of 13 la~inations secured to~ether by two rivets and having a total thickness of from .305 to .322 inches.
Stator 10 is thus designed to be mounted on existing mounting pads of an engine with convex surfaces 30 and 32 o~ legs 14 and 16, respectively, immediate adiacent the outer peripheral surface o~ a rotor o~ an existin~ conventienal internal combustion engine. The rotor has a pair o~ magnets disposed on its outer peripheral sur~ace which create a ti~ing var~ing magnetic flux in statox lQ, as the magnets rotate past stator lOo Thus, legs 14 ~nd 16 and inte~connec~ing poxtion 18 de~ine a conductive path for the ~lux created by thi;s rotating magnetic ~ield. As the ~lux ~s necessarily , . . . .
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tlme Varying with respec~ to st~tox 10, a ~olt~c will ther~by bc generated in coil asse~bly 12. The natu~e and effect of this voltage will be described in gxeatex detail below.
Figur~ 2 is a second embodiment of the in~ention ~howi~g a stator structure 42 ha~ing three le~s 44, 46 and ~8, spaced apart and extending substantiall~ parallel fxom an interconnecting portion 50. Le~ 44 has a longitudinally elongated aperture 52'located near its end opposite that of interconnecting portion 50. Similarl~, leg 4~ has a longi-tudinally elongated aperture 54 located near its end opposite that of interconnecting portion 5Q. Legs 44 and 46 each have respective conVe~ end surfaces 56 and 58, which have a radius of curvature similar to that of a rotor ~or which stator 42 is designed to be used. Also,,apertures 52 and 54 are located on respective leys 44 and 48, so as to coincide with existing mounting pads on an existing engine which is desired to be converted to a capacitive discharge ignition system. Stator 42 is constructed similarly to that of stator 10, having a plurality of. identical shaped laminations ~f electrical steel or other suitable magnetic material, secured by rivets 60 and 62 disposed on legs 4~ ~nd 48. Leg 48 is disposed at one end.of interconnectiny me~ber 5~ and preferably has a rounded end portion'64. Leg 48 is spaced ap~rt:from leg 46 a slightly greate~ distance than the distance bet~een leg 46 and leg 44. Stato~ 42 is a,dapted to be mounted on existing mounting pads o~ an existin~
conventional internal combustion engine ~ith conVex suxfaces 56 and S8 im~ediately ~djacent a rotox si~ilaxl~ to that .
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o~ ~tator 10. Thus, legs 44 ~nd 46 ~nd th~t portlon o~
inte~connecting portlon 50 extcndincl thcrebetween, de~ine conductive path for the ~a~netic ~lux induced by the enJine rotor. A coil assembly simil~r to that shown ~t 12 in ~gure 1 is mounted on leg 46 of st~tor 42 ~o~ ~ener~ting the ignition voltages. As leg 48 is spaced apart ~rom the r~tating magnetic field, it is effectively removed ~om the magnetic circuit and se~ves to pro~ide means to mount the stator 42 to the existing engine mountin~ pads while allowin~
the ignition timing Oæ the en~ine to be ~odiied by the angular displacement of the coil structure.
Stator ~2 is pa~ticulaxly suited ~or use in the xetxo~it of certain Briggs and Stratton en~ines. Xn suc~ an application, the radius of curvature ~ox con~ex sur~aces 56 and 58 will be of the order of. 2.885 to 2.890 inches and the stator will have a thickness on the order of .305 to .322 inches.
~ eferring now to Figure 3, another embodiment of a stator 64 is shown. Stator 64 has substantially parallel and spaced apart legs 66 and 68 extending rom interconnecting portion 70. Interconnecting portion 70 has a slightly wider portion 72 extending from leg 68 to a poin~ a~proximately midway between legs 66 and 68. Legs 66 and 68 also have convex end surfaces 74 and 76 similar to those previo~sl~
aescribed. Leg 68 has a ~ember 78 extending outward ~xo~
stator 64, perpendiculax to the longitudinal axis o~ leg 68 and disposed near convex end surface 76. Leg 68 ~lso has member 80 extending outward and subst~ntially pa~llel to mcmbe~ 78 ~ro~ the point of merc~ex between lecl 68 and ~9~7i77 .
lnterconnccting portion 70. Mcmbcr 80 is sli~htly sh~tcr than mcmber 78. A third membcr 82 extends between the ends o~ members 7~ and 80 and prot~udes a short distance be~ond member 78. Member 32 has lon~itudinall~ elongated ~pertures 84 and a6 adjacent opposite ends thereo~. Me~bers 78, 80, and 82 form a support arm and, with le~ 64~ enclose a genexally rectangular shaped aperture 88 therebetween~
Skator 64 is similarly constructed as those o~ Figures l and 2 having multiple laminations secured by rivets 9~
and 92 or the like. A coil assembly si~ilar to that at 12 of Figure 1 is disposed on leg 66. In this embodiment, legs 66 and 68 and interconnectin~ portion 70 define a magnetic Elux conducting path. As members 78, 80 and 82 do not extend from the same leg on which the cail assembly is disposed, any flux conducted by these members must also flow through leg 66, thereby contributing to the induction of voltage in the coil assembly. Thus, while members 78, 80 and 82 form an alternative flux path, it will not affect the voltage induced in coil 12.
Stator 64, described above, is particularly suited for adapting Beaird Poulan chain saw engine ignition systems to the capacitive discharge system of the present invention.
In such an application, convex surfaces 74 and 76 have a curVature radius on the order of 1.229 to 2.239 inches and are sym~etrical about an axis extending longitudinally approximately midway between legs 74 and 76.
~ i~ur~ 4 shows another embodiment of a stator 94 ~hich is similar to that of Fi~ure 3 and thus like portions are ~ndicated by like numerals. ~he only exception is th~t ~10-?
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~g~99777 member 96 does not extcnd beyond member 7a ~ut ~athex ~a~cs smoothly into member 78.
Th~ embodimcnt o~ Figure 4 is particul~rly suited for conversion of Roper 3.7 chain s~w engine ignition syste~s to the capacitive discharge syste~ of the preSent invcntion.
In such an applici~tion, convex surfaces 74 and 76 will have a radius of curvature on the order of 2.010 to 2.016 inches with leg 66 being slightly shorter than leg 68.
~ he coil assembly 12 shown generally in position o~ a stator structure lD in Figure 1 is illustrated in isolation and sectionali~ed in ~gure 5~ The coils are arranged as best seen in Figure 5 with a secondary coil 116 wound over the ~rimary ignition coil 118 and the auxiliary c~il 38 located forward o~ t~e ignition coils. Primary iqnition coil 118 and secondary ignition coil 116 comprise the ignition coils indicated at 40 in Figure 1. It is important to the operational sequence of the capacitive . discharge system that neither the primary nor secondary ignition coil windings be concentric with the auxiliary coil windings. ~urther, experimentation has shown that optimum results are obtained when a minimum 3/8" spacing between the ignition coils and the aux.iliary coil is maintained and the auxiliary coil is loc~ted forward of the ignition CQils. T~
order to facilitate assembly, the coils are wound on a for~
120 having a rectangular ox s~uaxe opening 121 xunning longitudinally therethrough and hayins xadially outwaxdly extending ~langes 122, 124 and 126 serving to aid in secuxin~
the coils in position. Form 120 may be ~abricated fxo~ any 6ult~b1e material such as pl~c~ic ~ox example.
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7~7 i Experimentation and reseaxch h~s shown th~t, bec~use o v~riation of dir~ction o;~ xotor xut~tion ~nd polarity of the leadin~ ma~netic pole, two dlffcrent windin~
configu~ations are required.
; In the ~irst of these coi:L configurations, the auxiliary, prima~y, ~nd secondary ignition coil windings ~re wound counterclockwise and all haye their finished ends connected to ground. This coil configuration is desi~ned to be used in all applica~ions in which the leading magnetic pole of the rotor is south see~ing, such as the Roper ~nd Beaird-Poulan engine previously xeferred to. Further, J
optimum results were achieved when the coil assembly ~as `
mounted on the first or leadin~ pole o~ the stator structure.
In the second configuration, both the auxiliary and primary ignition coils are wound counterclockwise and have the starting end connected to ground whereas the secondary ignition coil is wound clockwise and has its ` finished end connected to ground. This coil configuration is designed to ~e used in all applications in which the leading magnetic pole of the rotor is north seeking, such as the Briggs and Stratton engines previously re~erred to.
Furtherl op-timum results we~e achieved when the coil assembly was mounted on the second or trailing pole of the stator assembl~.
Experimentation has ~urther shown th~t the ~ollowing number of coil turns hnd wire gauges have given optimu~
performances:
~uxiliary Coil:
~wo ~ycle engine: 2,000 turns number 3~ wire.
Pour cyclc enqine; 4,000 turns number 40 wire.
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Pxim~ry Ignition Coil:
96 turns o~ numbcr 22 wire for both 2 ~nd ~ cycle engines.
Secondary Ignition Coil:
9,630 turns of number 44 wi~e ~or both 2 and 4 cycle engines.
~ he completed coil asse~bly will pre~erab:ly have an outer covering such as ~n e~oxy compound or the like to seal it against moisture or other potentially damaging - -elements. Also, the coil will have pxoVisions èxtexnally o~ this coVexing for the connection o~ the high voltage leaa, a ground connection, and primar~ ~nd auxiliary coil connection to the ignition module described below. ~lternati~el~, the coil may be constructed with the ignition module integral thereto assuming space limitations per~it. This will further simplify the conversion in that the only electrical connection required will be the high volta~e leacl.
In converting some engine ignition systems to the capacitive discharge ignition system, greater timing adjustment may be required than can be accomplished through the design of the stator structure alone. ~lternatively, space limitations of the engine structure may preclude the use of a modified st~tor structure embodyin~ isnitic.. timin~
corr~ction. Generally, in conventional m~gne~o i~nition ~ystems, the rotor is retained in position relati~e to its 6haft rotation by a woodruff keyway. Substitution o~
replace~ent rotor with a relocated keyway would ~reatly inC~ase the cost o~ any c~pacitive disch~r~e ignition ~onversion system thus m~king a conversion kit p~ohibitively ., ' , .
-~3-, ~U9~'777 expensive. Accoxdingly, a kcyway shiftcr, as ~hown ~t 98 ln ~iguxe 6, is pro~ided. ~he kcyway shi~tex includes ~Wo slmilarly shaped disc~ e portions 100 and 102, both generally round in shape. Section 102 has an aperture 103 therein of a dia~eter equal to o~ slightly larger than the diameter of a crankshaft to which the keyway shifter iS to - be fitted so as to allow it to be slipped over the shaft. A J
protrusion 104 extends axially outward from the edge of aperture 103 and is of cross sectional size appro~imatin~
that of a keyway slot 106 on ~ rotor 107 as shown in Figure 8. Section 100 also has an aperture 109 therein o~ ~
diameter approximatel~ the same as shaft 108 of an engine and aperture 103. A protrusion 110 extends axially out~ard -from the ed~e of the aperture and has a transyerse cross sectional size approximately that of a keyway slot 112 on shaft 108. The two sections 100 and 102 are welded to~ether with the angle between the protrustions 110 and 104 bein~
adjusted to accomplish a predetermined timing change of the rotor. This angular displacement is best seen by reference to Figure 7 showing a keyway shi~ter of Figure 6 as viewed along a line indicated ~enerally by arrow ~ of Figure 6.
The installation and operative relationship of keyway shifter 98 is best seen with reference to Figure 8 in Which a rotor 107 is illustrated partially broken away but ~therwise in operatiVe relationship to a crankshaft 108 of a~ internal combustion engine. Crankshaft 108 is disposed in a cylindrical bore 113 extending thxough Xo-tor 107.
Rotor 107 has a keyway slot 106 disposed on the periphe~al - ~urface of bore 113 and crankshaft 108 has a similar keyway ~lq~
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~9~1~7~7 slot 112 disposcd on its p~ripher~l sur~t~ca, As ~x~inally manufactured with the conventional ignition s~stem keyway ~lots 112 and 10~ are aligned and retain a wood~uP~ key to prevent relative rotation. In oxder to install .the keyway 8hifter o~ the present invention, the woodru~f key is ~irst removed thus allowing rotor 107 to he rotated relative to shaft 108. ~rotrusion 110 of keywa~ shifter 98 is first inserted in keyway slot 112, rotor 107 is then rota~cd wi~h xespect to shaft 1~8 to brin~ keyway 106 into alignment with protrustion 104 of keyway shifter 98 thus allowing section 102 of keyway shifter 98 to engage the upper surface 114 of : :~
rotor 107. A jam nut.115 is then tigh.tened down over keyway shifter 98 and rotor 107 thus securing th.em to sh.~t lQ8.
It is possible in certain applications that the key~tay slot on the rotor may not extend completely through to the top surface thereof or the keyway slot on the crankshaft may not extend to the upper end of the shaft. This situation usually occurs whe~ the keyway slots have been formed by a milling machine. In either case, in order to install the keyway shifter of the present inventio~,.it will be necessary to extend the keyway slot so as to provide openings for ~he keyway shifter to seat in. This ~ay easily be done hy filing of the rotor or crankshaft.
Refcrring now to Figures 9 and 10, the operation of the present invention will be described in detail. A
coil assembly is shown schematically at 128 o~ Fl~u~e 9. In operative positionl the coil and appropriate st~tor structuxe described above would be securely mounted to the en~lne adjacent ~he rotor oarrying the magnetic ~ieId ~eneratln~ ~:
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~ b9~77 - mcans. An ignition module, ~s shown schem~tically ~t 130 o~
Figure 9 is mounted on the engine in an~ conVenient loca~ion and ls eleckrically coupled to the c:oil asseJnbl~ b~ conductors 132 and 134. Both the coil assembl~ and i~nition modulc J
have means 136 and 138, xespectivel~, for cre~tin~ ~n electrical eonnection to ground which, in this case, may be the engine ~tself. Additionally, coil assembly 128 has a hiyh volt~ge conductor 140 for conducting the ;ignition volta~e to the spark plug.
~- As the rotating m~gnetic field, carried by the rotor, passes in close proximity to the stator co~e, it induces therein a time varYing magnetic ~lux, ~s this ~lux inereases in magnitude, it induces a voltage in the auxiliary eoil which causes a current to ~low fxom the coil assembly along conductor 132 through diode 142 and conductor 144 to eapacitor 146 creating a positive charge thereon. Diode 148 is eonnected between conductor 132 and ground 138 and serves to dampen negative spikes induced in the auxiliary coil.
The voltage~ induced in the auxiliary coil, as this ti~e varying magnetie field increases in intensity, is plotted against time in gr~ph 150 of Figure 10 with maximum intensity being achieved at point 152. Graph 154 shows the voltage vs. time plot o~ the charging of capacitor 196 in response to the induced voltage on the auxiliary coil. As shown graphieally, capacitor 146 achieves a maximum charge ~t point 156 which corresponds in ti~e to the ~aximum rate of ~hange of flux intensity passing through the st~to~ coil.
hs diode 142 only conducts in one direction, the chaxge on capacltor 146 wlll be maintained.
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A switch moans 158, such ~s a silicone contxollcd rectiier ~SCR), is pxovided between capacito~ 146 and pxima~y conductor 13~ connected to the prima~y coil winding.
A xesistor 160 ~nd a diode 162 axe c:onnected in p~rallel between the cathod~ 164 and gate 166 o~ SCR 158. Diode 162 serves to protect SCR 158 from positiVe t~ansients lnduced in the primary coil winding during the chargin~ o~ capacitor 146.
As the rotating ma~netic ~ield begins to moye out . . .
of alignment with the statox, the ~agnetic flux followin~
thexethrough begins to drop. This then causes a negatiye voltage to be induced in the primar~ coil, thus c~using a ~urrellt to ~low throu~h conductor 134. This will then cause gate 166 of SCR 158 to be positively biased with respect tQ
cathode 164, thus causing SCR 158 to become conductive.
This is shown pictorially on graph 168 of Figure 10, which pIots voltage vs. time as measured across the primary winding.
When SCR 158 becomes conductive, capacitor 146 will dis-charge through SCR 158 and through primary coil 170. As ;~ the primary and secondary ignition coils are magnetically coupled, the discharge through primary coil 170 cooperatively with the time varying magnetic flux induces the ignition spark generating vo'tage in secondari~ coil 172.
In order to maintain maximum operating e~ficiency o~ the engine~ it is important to insure capacitor 146 will repetitiYely fire at precisel~ the same time rel~tive to the an~ular position o~ the cr~nkshat with as little ~ariation as possible over the entire b~oad speed r~nge o~
the en~ine. It has been ~ound through experiment~tion that ; ' ' .. ~, , -I
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the ignition modul~ circuit o~ ~igure 9 in coope~Atlon wlth the degxee o~ magnetic~couplincJ of the l~nition ~nd auxiliary coils and thei~ polarity ~elationships plus the lack of frequency sensitivit~ in the SCR gate network produc~
gxeater timing stability than found in conventional ignition s~stems.
In certain applications,.it is desixable to have ,the sp~rk timing retarded during starting of the engine : ~ut,,when the engine is at operatiny speed, it becomes necessary to advance the ignition timing in order to obtain m~ximum engine efficiency, Accordingly, it is desira,ble to pxovide means which would automatically ~ccomplish this with-out increasing the costs of the conVersion contemplated herein.
'Fagure 11 shows a stator structure 174 s.imila~
to,that shown in Figure 2 but incorporating a further ,modification which automatically advances.the ignition ' timing'as engine speed increases. Stator 174 is identical . to stator 42 with the exception of lower leg portions 176 and 178 respectively. Leg portion 176 is divided into two spaced apart segments 180 and 182. Segment 180 extends ' laterally and lorgitudinally ~rom the main portion of leg 46 and is slightly longer th~n segment 182 so as to provid~
a smaller air gap betwcen the stator and.rotor when installed on an engine. Both segments h~ve convex end surfaces 184 and 186 as previously described or stator 4 2 of Figu~e 2.
Similarly, leg portion 178 is diyided into twa se~ments 188 and 190. Se~ment 188 extends later~ nd lon~itudinally . ~om the main portion of leg 44 in the s~me direction a5 ~egment 180 and is also slightly.longs~ tha,n seg~ent 190.
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- : . . :~: : ;:: .. :: . :........ .. :
:: . : . . :. ~ . . . .: i :;
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Both segments 188 ~nd 190 have convex end surf~ces 192 and 194 similar to those previously described. There is thus provided a slow speed flux path co~prising se~ment lB8, leg 44, interconnecting portion 50, le~ 46, ~nd segment 180, and a high speed flux path comprising segment 190, leg 44, interconnecting portion 50, leg 46 and seg~ent 182.
At low speed operation, the trailing segments 180 and 188 provide a significantl~ greater operating flux.for inducing the ignition voltage in the coil due to -the relatively smaller air gap relative to that created b~ segments 182 and 190. As these sections are shifted slightly in the dlrection of rotor rotation relative to the ~ain leg of the stator, the ignition timing during high speed operation is advanced relative to the ign~tion timing during low speed operation. As the operational speed increases, the magnetic flux provided by the leading pair of stator leg segments 182 and 190 will induce an increasing].y greater voltage in the coil due to the increased r~te of change of the magnetic field. This ignition voltage will necessarily be advanced relati~e to that induced from the flux provided by the traiIing ssgments 180 and 188 due to the relative position o~ the sections. Thus,.at a suf~iciently hlgh operating speed, the time varying ~agnetic flux provided by the leading pair o stator le~ seg~ents 18~ and 190 will induce a voltage in the ignition coil sufficiently large to .
cause the associated capacitiVe discharge ignition circuitry, ~.
as described above and in the two prev~ousl~.re~exenced applications, to operate. There ls thexeby created means r Which will automat~cally cause.the ignition timing to advance .
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7i9~
ln r~sponse to increased engine speed. The positi~ning o~
the leg secti~s relativc to e~oh othc~ ~nd xel~tive to the angle of rotation of the rotor will contxal the de~ee o~
timing advance or retardation.
Figuxe 12 shows a st~tor stxuctu~e 196 similar to that of Figure 1 but having a further modi~ication si~il~x to that previously described fo~ stator 174 o~ Fi~ure 11 incorporated thereon.- Stator 196 h~s lower leg po~tions 1~8 and 200, e~ch of which is divided into two segments 2Q2, 204, 206 and 208 t respectively. As pre~iously de,sc~ibed with reference to ~igure 11, segment 202 is slightly longer than segment 204 and segment 206 is slightl~,'longe~ th~n se~ment 208 and all segments haye conVex end surfaces thereon., The operation of this modlfication is identical to tha~ des~
cribed with reference to stator 17~ ~f Figure 11.
Figure 13 in like manner sho~s a stator structure 210 similar to that of Figure 3 but incorpor~ting thereon the modi~ication similar to that previously described for stators 174 and 196 of Figures 11 and 12, respectively. Stator 210 has lower leg portions 212 and 214, each of which is divided into two segments 216, 218, 220 and 222, respectively, all of which have convex end surfaces. Segment 216 is slightly shorter than segment 218 and se~ment 220 ls slightly shorter than segment 222. The operation of this m~dification is identical to that previously described ~ith ~e~erence ~o ~tator 174 of Fi~ure 11, a,low speed ~lu~ p~th bein~ defined by segment 218, leg 6~, interconnecting po~tion 70, le~ 68, ~nd segm~nt 222 and a high s~eed flux path bein~ de~lned b~
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~egmcnt 216~ le~ 66, inte~conncctin~ po~tion 70~ leg 68, and segm~nt 220, It should also be noted th4t this ~odiica-: k~on may bc incorporated into the deslgn o~ st~tor 94 o~
Figure 4 in like ~anner as descxibed with re~exence to stator 210.
Reference is now made to Figures 14 throu~h 16 in which-is illustrated the sequence of operations by which : . an owner of an existing machïne ha~in~ an iternal combustion engine with a convent.ional i~nition syste~ may ayail himself of the advantages of the capacitive discharge ignition system o~ the present invention. In Figure 14,.there is illustrated an internal combustion en~ine 224 which was manufactured with a conventional i~nition system. The i~nition system comprises a rotor 226 havin~ a north. ma~netic pole 228 and a south ma~netic pole 230 spaced a short dis-tance apart and disposed on the peripheral.surface of rotor 226. The original stator 232 and coil assembly 234 is mounted on engine housing 236 i~mediately adjacent rotor 226 through the agency of bolts 238 and 240.
In order to convert this ignition system to that . of the present invention, the existing stator 232 and coil assembly 234 is removed. As shown in Figure 15, there is then exposed two mounting pads 242 and 244, which cooperate with bolts 238 and 240 to secure the stator and coil assembly.
A stator 248 havin~ a coil assembly 246 mounted thereon, both in accordance with the p~esient inyention, is the~ securcd to the mounting pads 242 and 244 through the agency o~ bolts 238 and 240 p~ssing through e}ongated g `
"', .', ~99~7~77 .
apcrtures 239 and ~41. These olon~at~d apcrtures ~ll.ow ~tator 2~6 to then be positioned to a~ d the px~determined air gap between it and rotor 226, wld bolts 2~8 and 240 are then tightened thus securing stator 298 in position. The ignition module previousl~ described may be mounted in any convenient location on the machine and is electrically connected to coil assembly 246 b~ means of conductors 250, 252 and 254. ~ltexnatively, the stator and coil assembly ~ay be fabricated with the ignition module bein~ integral thereto thus further simpli~ying the conversion.p~ocess throu~h the elimination o~ the electrical connections. High voltage conductor 256 is connected to the spark plug thus completing the installation of the ignition s~stem of the present.invention. It should be noted that the ignition timing has been adjusted by means of the construction of the new stator 248, as may be readily seen in a comparison of Figures 14 and 16.
A similar conversion of an internal combustion engine of a chain saw is illustrated in Figures 17 thro~gh 19. Figure 17 shows the en~ine.258 having a conventional ignition system comprising a stator 260 secured to engine 258 by volts 262 ~nd 264, a coil assembly 266 mounted on stator 260, and a rotor 268. Rotor 268 has ~ north ma~netic pole and a south magnetic pole spaced sli~h.tl~ apart ~nd disposed on its outer periphery ~o~ ~eneratin~ the time varying magnetic ~lux in stator 260.
.
In installing the stator and coil assembly o~ the . present invention, the existing stator 260 ~nd cQil ~ssembly 26~ are removed from engine 258 by removal o~ bolts 262 and ~ ' ' .
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264. Thus thcrc is exposed mounting pads 270 ~nd 272 disposed on enyine 258 as best 5een in Figure lB. The new stato~ 274 and coil assembly 276 o~ the p~esent inyention are then mounted on engine mountin~ pads 270 and 272 through the ayency of bolts 262 and 264, St~tor 274 is then positioned to afford the proper air gap between it and.rotor 268 and ~olts 262 and 264 a~e tightened, thus securing statcr 274 in operative position~ The iynition module previously described is then mounted in any convenient.location and electrica}ly connected to coil assembly 276 or alternatively may be integral with the stator and coil assembly as pre-~iously described. It will be noted b~ a comparison of Pigures 17 and 19 that the ignition timing has been shi~ted approximately 18 through the use of the stator structure of the present invention, thus eliminating the need for any structural modification of the engine itself.
~here is thus disclosed herein means by which . .
. . any individual having a very few basic tools may easily convert the existing ignition system of his lawnmower or the like to the capacitive discharge ignition system of the present invention. As is apparent from the above description r there is provided means by which the difference in ignition timing of the capacitive aischarge ignition system relative to the conventional ignition system may be compensated for so as to maintain the ignition timing o~ the en~ine.
The absence of any necessity to pexfor~ delicate machinin~
operations or the need for any complex engine ~odific~tions makes it possible to completely elimin~te the need for any knowledge whatsoever o~ machinery operations o~ engine .
. -23-..
~ , . -,, . ~ - ~
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: , ~ ~ 9 9!7 ~ 7 ignitlon system theory by the owncr. Fu~thcr~ ag the re-placemcnt of parts ls minimized, the individual ~a~ achieve the advantages inherent in a capacitive dischar~e ic~nition system at a relatively small investment of money and time.
It is to be undcrstood that the forec~oing des-cription is that of preferred embodiments of the in~ention.
V~rious changes and modifications ~a~ be made without departing from the spirit and scope of the inventiQn as de~ined by the appended claims.
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1,~34,1~8, issued July 4, 1978.
Previously, the complex nature oP capacitive discharge ignition systems made them prohibitively expensive for application to smaller internal combustion engines presently utilizing simple magneto ignition systems. With the development of the improved system disclosed in the above referenced copending applications, the number of components, package size, complexity and cost have been reduced sufficiently to allow the incorporation of such systems into these smaller sized engines such as are used in lawnmowers, chain saws, outboard motors, and the like. The ignition system of the aforementioned patent is generally applicable for incorporation during original e~uipment~manufacture of the associated engines. The present invention provides an inexpensive ignition replacement package whereby existing conventional magneto ignition systems may be easily converted to this improved capacitive discharge system ~ by the owner of the engine subsequent to its initial purchase.; The substantial achievement of this invention can be appreciated when the nature of existing engines and their J
associated ignltion systems is considered. In order for mb~
~9~77 a conversion kit to be commercially practical, it must be adaptable for use with a variety of engine configurations.
Conventional magneto systems may have a rotor rotating either clockwise or counterclockwise. Also, the Leading magnetic pole may be either north or south seekin8 ; Further, the ignition timing of the existing ignition system may not be appropriate due to the differing response characteristics. Additionally, varying existing space limitations must be considered since a conversion would not be commercially practical if significant engine structure modifications were required. The present invention as described herein bridges wide variations in engine and existing ignition systems so as to provide a conversion kit in which a minimum of component structure variations will accommodate a large variety of engine and ignition system configurations without structural modifications.
Specifically, the present invention relates to a capacitor discharge system for an internal combustion engine comprising a permanent magnet means rotated about a circular path in synchronism with the operation of the engine, a core of ferromagnetic material mounted adjacent the circular path and having one portion providing a path for the varying flux generated by the movement of the magnet means past the core, a charging winding and a transformer core portion. The charging winding is offset from the primary and secondary windings with respect to the circular path, the charging winding and primary winding being wound on the one core portion such that the voltages mb/!, - 2 -,.. -~ .. , . . ,,.,. . . "
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~977~
induced therein by the varying flux each inclLIdes half wave voltages of opposite polarity. A charging circuit is provided including a capacitor connected across the charging winding and a diode poled to pass half wave voltages of one polarity for charging the capacitor and maintaining the capacitor charged when the voltage generated in the charging winding is opposite the one polarity. Circuit means connect the capacitor with the primary winding for discharging the capacitor through the primary winding and include an electronic switch means having anode, cathode and control electrodes, the anodecathode junction of the switch means interconnecting the ends of the charging winding and the primary winding which are simultaneously at the same polarity. The control electrode is connected to the other end of the primary winding, the polarity of which is opposite this same polarity. The switch means is nonconductive during the charging of the capacitor by this one polarity of the voltage generated in the charging coil and is rendered conductive by voltage generated in the primary winding opposite this same polarity whereby the capacitor is charged during one complete half cycle of voltage generated in the charging coil and discharged during the next half wa~e voltage generated in the charging winding.
~dditional advantages and features of the present J
invention will become apparent from the following detailed ~ description taken in conjunc~ion with the attached drawings ; and appended claims.
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BRIEF ~ESCRIPTION OF THE DRAWI~GS
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Figure 1 is a perspective view of a coil wound upon a stator having ~.wo legs with mounti.ng provisions contained thereon all in accordance with the present invention;
Figure 2 is a second embodiment of the present invention showing a stator structurs with a third leg for accommodating an existing mounting structure;
Figure 3 is a third embodiment of the present invention showlng a stator structure employing yet another mounting arrangement;
Figure 4 is a fourth embodiment of the present invention similar to that of Figure 3 but employing a different mounting structure;
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, - ' mb/),) - 3a -g ~ 9~77 .
Fi~ure 5 is a sectional ~idc ~icW o~ thc c~il assembly utilized in conjunction with the co~e structurcs o~
the present invention;
Figure 6 is an edge view o a keywa~ shi~tex ~ox use ln altering the axisting timing se~uence;
Figure 7 is another view o~ the ke~w~ shi~ter of Figure 6 as viewed ~rom the direction of arrow A of ~igure 6;
Figure 8 is a sectional perspectiye view of a portion o~ a crankshaft o~ an internal combust.ion engine having a rotor mounted thereon and sho~ing a ke~ywa~ shifter installed in operatiye relation thereto;
Fi~ure 9 is a schematic dia~ram o~ the capacitiye ignition system in accordance with the present invention;
Figure 10 is a graphical plot of volta~e Vs. time showing the operating waveforms for a capacitive discharge ignitio~ system of the present inyention;
Figure 11 is yet another embodiment of the present ~nvention similar to that of Figure 2 but having split leg sections;
Figure 12 is another embodiment of the present i~Vention similar to that o~ Figure 1 but also havin~ split leg sections~thereon;
Figure 13 is yet another embodiment o~ the present inVention similar to that of ~lgure 3 but haying s~lit le~ J
6ections incorporated thexeon;
Figu~es 14 through 16 ~re o~ ~ t~piaal existing lawnmower engine with the sheet metal cowlin~ xe~oved and ~howing, in sequence,` a convention~l ignition system inst~lled , ~, :' .
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ther~on, the cngine with thc conventional ignition s~ste~ co$e ~nd coil assembl~ remov~d and the engine with ~ core ~nd coil assembly of the pres~nt invention installcd ther~on; and Pigur~s 17 through 19 are o~ a typic~l existing chain saw engine with the sheet metal cowling ~cmoved and also showing, in se~uence, the existing engine ignition ~yste~, the removal thereoE, and a core and coil of the present invention installed thereon.
DESCRIPTION OF THE PRE:FERRED EMBODIMENT
Re~erring now to Figure l, a stator 10 is shown containing a coil assembly 12 on one leq thereo~. Stator 10 has a generally rectangular cross section and is ~enerally nu" shaped having a pair o~ spaced apart substantially parallel legs 14 and 16 and an interconnecting por~ion 18 extending between and connecting one end of each of legs 14 and 16. Leg 14 has a protrusion 15 extending outward there-from and disposed approximately midway along its length.
Leg 14 also has an elongated aperture 2a adjacent pxotrusion 15 and extending along the longitudinal axis thereo~.
Interconnecting portion 18 has one side 22 which is per-pendicular to the longitudinal axis of legs 14 and 16 and a second side 24 which is bowed outward Crom side 22 so as t~ have a maximum width portion 26 at a point slightly offset toward leg 16 from its ~idpoint. Also, inte~-connecting portion 18 similarly has an elongated aperture 28 disposed adjacent portion 26 and extendin~ between sides 22 and 24 and parallel to aperture 20. ~pertures 2~ and 2B ar~ located on stator 10 so a~ to coincide with existing : ~ :: , ,: :
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~977~
mounting pads provided on an internal combustion enqine and are substantially e~ually elonyated, thus p~ovidin~ mcans by which the air gap ~etween the stator and a rot~ting magnetic fleld may be adjustea, as is described in greater detail ~elow. Legs 14 and 16 axe substantially equal in length and have respective convex end surfaces ~0 ~nd 32 thereon.
' Conventionally, the cores o~ magneto ignition systems are constructed o$ cold rolled steel. Cold rolled steel cores are used since the cold rolled steel is an excellent collector of ~lux emanatlng fro~ the permanent magnets of the rotor~ Althou~h the core material of the i,gnition systems disclosed herein c~n be' cold rolled steel, it has been discovered that electric~l steel, i.e.~ steel containing a silicone alloy as is used in transformer core constructions, provides a substantial increase ln the output voltage of the ignition system. For example/ output voltage increases of 40~ have been obtained using electrical steel.
It is believed that this substantial increase in output voltage is due to the ~act that cold rolled steel is not a desirable core material for the ignition coil so that the voltage rise upon discharging of the capacito into the primary winding of the ignition coil is hampered. The electrical s,teel is a more effective core for the ignition coil than cold xolled steel, and yet has a good capability of collecting the 1ux emanating from the permanent ma~nets o the rotor. The usual core matarials for i~nition coils are errite materials. These materials would not be satis-iactory as a core material or the ignition system since they would not be good collectors o~ the flux eman~ting ~rom the , 6- , ~
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permanont magnets o~ thc roto~ Accordinql~, stato~ 10 is preerably constructed of multiple la~inations o~ elect~ic~1 st~el secured by two rivets 34 and 36 as shown in Figure 1 or other like ~astening devices.
Leg 16 o~ stator 10 has coil assembl~ 12 surroundin~
its longitudinal midportion. Coil ~ssembly 12 com~rises auxiliary coil 38 located adj~cent convex sur~ace 32 and ignition coils 40 disposed i~mediately behind auxiliary coil 38. Coil assembly 12 will be described in greater detail belo~
Stator 10 is particularly suited ~o~ use with the Rope~ 2.5 chain saw engine i~nition syste~. In such an application, convex sur~aces 30 and 32 haye a curyature radius o~ between 1.760 and 1.764 inches and are s~metric~l about a longitudinal axis extending approximately equ~distant between legs 14 and 16. Further, in such an application, the stator structure is constructed of 13 la~inations secured to~ether by two rivets and having a total thickness of from .305 to .322 inches.
Stator 10 is thus designed to be mounted on existing mounting pads of an engine with convex surfaces 30 and 32 o~ legs 14 and 16, respectively, immediate adiacent the outer peripheral surface o~ a rotor o~ an existin~ conventienal internal combustion engine. The rotor has a pair o~ magnets disposed on its outer peripheral sur~ace which create a ti~ing var~ing magnetic flux in statox lQ, as the magnets rotate past stator lOo Thus, legs 14 ~nd 16 and inte~connec~ing poxtion 18 de~ine a conductive path for the ~lux created by thi;s rotating magnetic ~ield. As the ~lux ~s necessarily , . . . .
~ . , .
~399~7~
tlme Varying with respec~ to st~tox 10, a ~olt~c will ther~by bc generated in coil asse~bly 12. The natu~e and effect of this voltage will be described in gxeatex detail below.
Figur~ 2 is a second embodiment of the in~ention ~howi~g a stator structure 42 ha~ing three le~s 44, 46 and ~8, spaced apart and extending substantiall~ parallel fxom an interconnecting portion 50. Le~ 44 has a longitudinally elongated aperture 52'located near its end opposite that of interconnecting portion 50. Similarl~, leg 4~ has a longi-tudinally elongated aperture 54 located near its end opposite that of interconnecting portion 5Q. Legs 44 and 46 each have respective conVe~ end surfaces 56 and 58, which have a radius of curvature similar to that of a rotor ~or which stator 42 is designed to be used. Also,,apertures 52 and 54 are located on respective leys 44 and 48, so as to coincide with existing mounting pads on an existing engine which is desired to be converted to a capacitive discharge ignition system. Stator 42 is constructed similarly to that of stator 10, having a plurality of. identical shaped laminations ~f electrical steel or other suitable magnetic material, secured by rivets 60 and 62 disposed on legs 4~ ~nd 48. Leg 48 is disposed at one end.of interconnectiny me~ber 5~ and preferably has a rounded end portion'64. Leg 48 is spaced ap~rt:from leg 46 a slightly greate~ distance than the distance bet~een leg 46 and leg 44. Stato~ 42 is a,dapted to be mounted on existing mounting pads o~ an existin~
conventional internal combustion engine ~ith conVex suxfaces 56 and S8 im~ediately ~djacent a rotox si~ilaxl~ to that .
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7~
o~ ~tator 10. Thus, legs 44 ~nd 46 ~nd th~t portlon o~
inte~connecting portlon 50 extcndincl thcrebetween, de~ine conductive path for the ~a~netic ~lux induced by the enJine rotor. A coil assembly simil~r to that shown ~t 12 in ~gure 1 is mounted on leg 46 of st~tor 42 ~o~ ~ener~ting the ignition voltages. As leg 48 is spaced apart ~rom the r~tating magnetic field, it is effectively removed ~om the magnetic circuit and se~ves to pro~ide means to mount the stator 42 to the existing engine mountin~ pads while allowin~
the ignition timing Oæ the en~ine to be ~odiied by the angular displacement of the coil structure.
Stator ~2 is pa~ticulaxly suited ~or use in the xetxo~it of certain Briggs and Stratton en~ines. Xn suc~ an application, the radius of curvature ~ox con~ex sur~aces 56 and 58 will be of the order of. 2.885 to 2.890 inches and the stator will have a thickness on the order of .305 to .322 inches.
~ eferring now to Figure 3, another embodiment of a stator 64 is shown. Stator 64 has substantially parallel and spaced apart legs 66 and 68 extending rom interconnecting portion 70. Interconnecting portion 70 has a slightly wider portion 72 extending from leg 68 to a poin~ a~proximately midway between legs 66 and 68. Legs 66 and 68 also have convex end surfaces 74 and 76 similar to those previo~sl~
aescribed. Leg 68 has a ~ember 78 extending outward ~xo~
stator 64, perpendiculax to the longitudinal axis o~ leg 68 and disposed near convex end surface 76. Leg 68 ~lso has member 80 extending outward and subst~ntially pa~llel to mcmbe~ 78 ~ro~ the point of merc~ex between lecl 68 and ~9~7i77 .
lnterconnccting portion 70. Mcmbcr 80 is sli~htly sh~tcr than mcmber 78. A third membcr 82 extends between the ends o~ members 7~ and 80 and prot~udes a short distance be~ond member 78. Member 32 has lon~itudinall~ elongated ~pertures 84 and a6 adjacent opposite ends thereo~. Me~bers 78, 80, and 82 form a support arm and, with le~ 64~ enclose a genexally rectangular shaped aperture 88 therebetween~
Skator 64 is similarly constructed as those o~ Figures l and 2 having multiple laminations secured by rivets 9~
and 92 or the like. A coil assembly si~ilar to that at 12 of Figure 1 is disposed on leg 66. In this embodiment, legs 66 and 68 and interconnectin~ portion 70 define a magnetic Elux conducting path. As members 78, 80 and 82 do not extend from the same leg on which the cail assembly is disposed, any flux conducted by these members must also flow through leg 66, thereby contributing to the induction of voltage in the coil assembly. Thus, while members 78, 80 and 82 form an alternative flux path, it will not affect the voltage induced in coil 12.
Stator 64, described above, is particularly suited for adapting Beaird Poulan chain saw engine ignition systems to the capacitive discharge system of the present invention.
In such an application, convex surfaces 74 and 76 have a curVature radius on the order of 1.229 to 2.239 inches and are sym~etrical about an axis extending longitudinally approximately midway between legs 74 and 76.
~ i~ur~ 4 shows another embodiment of a stator 94 ~hich is similar to that of Fi~ure 3 and thus like portions are ~ndicated by like numerals. ~he only exception is th~t ~10-?
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,~ . ' ,:; ' ' ' , , " :
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~g~99777 member 96 does not extcnd beyond member 7a ~ut ~athex ~a~cs smoothly into member 78.
Th~ embodimcnt o~ Figure 4 is particul~rly suited for conversion of Roper 3.7 chain s~w engine ignition syste~s to the capacitive discharge syste~ of the preSent invcntion.
In such an applici~tion, convex surfaces 74 and 76 will have a radius of curvature on the order of 2.010 to 2.016 inches with leg 66 being slightly shorter than leg 68.
~ he coil assembly 12 shown generally in position o~ a stator structure lD in Figure 1 is illustrated in isolation and sectionali~ed in ~gure 5~ The coils are arranged as best seen in Figure 5 with a secondary coil 116 wound over the ~rimary ignition coil 118 and the auxiliary c~il 38 located forward o~ t~e ignition coils. Primary iqnition coil 118 and secondary ignition coil 116 comprise the ignition coils indicated at 40 in Figure 1. It is important to the operational sequence of the capacitive . discharge system that neither the primary nor secondary ignition coil windings be concentric with the auxiliary coil windings. ~urther, experimentation has shown that optimum results are obtained when a minimum 3/8" spacing between the ignition coils and the aux.iliary coil is maintained and the auxiliary coil is loc~ted forward of the ignition CQils. T~
order to facilitate assembly, the coils are wound on a for~
120 having a rectangular ox s~uaxe opening 121 xunning longitudinally therethrough and hayins xadially outwaxdly extending ~langes 122, 124 and 126 serving to aid in secuxin~
the coils in position. Form 120 may be ~abricated fxo~ any 6ult~b1e material such as pl~c~ic ~ox example.
:~ : .
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7~7 i Experimentation and reseaxch h~s shown th~t, bec~use o v~riation of dir~ction o;~ xotor xut~tion ~nd polarity of the leadin~ ma~netic pole, two dlffcrent windin~
configu~ations are required.
; In the ~irst of these coi:L configurations, the auxiliary, prima~y, ~nd secondary ignition coil windings ~re wound counterclockwise and all haye their finished ends connected to ground. This coil configuration is desi~ned to be used in all applica~ions in which the leading magnetic pole of the rotor is south see~ing, such as the Roper ~nd Beaird-Poulan engine previously xeferred to. Further, J
optimum results were achieved when the coil assembly ~as `
mounted on the first or leadin~ pole o~ the stator structure.
In the second configuration, both the auxiliary and primary ignition coils are wound counterclockwise and have the starting end connected to ground whereas the secondary ignition coil is wound clockwise and has its ` finished end connected to ground. This coil configuration is designed to ~e used in all applications in which the leading magnetic pole of the rotor is north seeking, such as the Briggs and Stratton engines previously re~erred to.
Furtherl op-timum results we~e achieved when the coil assembly was mounted on the second or trailing pole of the stator assembl~.
Experimentation has ~urther shown th~t the ~ollowing number of coil turns hnd wire gauges have given optimu~
performances:
~uxiliary Coil:
~wo ~ycle engine: 2,000 turns number 3~ wire.
Pour cyclc enqine; 4,000 turns number 40 wire.
, . 12 : . , ~ ~ .
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B
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Pxim~ry Ignition Coil:
96 turns o~ numbcr 22 wire for both 2 ~nd ~ cycle engines.
Secondary Ignition Coil:
9,630 turns of number 44 wi~e ~or both 2 and 4 cycle engines.
~ he completed coil asse~bly will pre~erab:ly have an outer covering such as ~n e~oxy compound or the like to seal it against moisture or other potentially damaging - -elements. Also, the coil will have pxoVisions èxtexnally o~ this coVexing for the connection o~ the high voltage leaa, a ground connection, and primar~ ~nd auxiliary coil connection to the ignition module described below. ~lternati~el~, the coil may be constructed with the ignition module integral thereto assuming space limitations per~it. This will further simplify the conversion in that the only electrical connection required will be the high volta~e leacl.
In converting some engine ignition systems to the capacitive discharge ignition system, greater timing adjustment may be required than can be accomplished through the design of the stator structure alone. ~lternatively, space limitations of the engine structure may preclude the use of a modified st~tor structure embodyin~ isnitic.. timin~
corr~ction. Generally, in conventional m~gne~o i~nition ~ystems, the rotor is retained in position relati~e to its 6haft rotation by a woodruff keyway. Substitution o~
replace~ent rotor with a relocated keyway would ~reatly inC~ase the cost o~ any c~pacitive disch~r~e ignition ~onversion system thus m~king a conversion kit p~ohibitively ., ' , .
-~3-, ~U9~'777 expensive. Accoxdingly, a kcyway shiftcr, as ~hown ~t 98 ln ~iguxe 6, is pro~ided. ~he kcyway shi~tex includes ~Wo slmilarly shaped disc~ e portions 100 and 102, both generally round in shape. Section 102 has an aperture 103 therein of a dia~eter equal to o~ slightly larger than the diameter of a crankshaft to which the keyway shifter iS to - be fitted so as to allow it to be slipped over the shaft. A J
protrusion 104 extends axially outward from the edge of aperture 103 and is of cross sectional size appro~imatin~
that of a keyway slot 106 on ~ rotor 107 as shown in Figure 8. Section 100 also has an aperture 109 therein o~ ~
diameter approximatel~ the same as shaft 108 of an engine and aperture 103. A protrusion 110 extends axially out~ard -from the ed~e of the aperture and has a transyerse cross sectional size approximately that of a keyway slot 112 on shaft 108. The two sections 100 and 102 are welded to~ether with the angle between the protrustions 110 and 104 bein~
adjusted to accomplish a predetermined timing change of the rotor. This angular displacement is best seen by reference to Figure 7 showing a keyway shi~ter of Figure 6 as viewed along a line indicated ~enerally by arrow ~ of Figure 6.
The installation and operative relationship of keyway shifter 98 is best seen with reference to Figure 8 in Which a rotor 107 is illustrated partially broken away but ~therwise in operatiVe relationship to a crankshaft 108 of a~ internal combustion engine. Crankshaft 108 is disposed in a cylindrical bore 113 extending thxough Xo-tor 107.
Rotor 107 has a keyway slot 106 disposed on the periphe~al - ~urface of bore 113 and crankshaft 108 has a similar keyway ~lq~
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. . ..
~ . . . ,, , . ~ ~
~9~1~7~7 slot 112 disposcd on its p~ripher~l sur~t~ca, As ~x~inally manufactured with the conventional ignition s~stem keyway ~lots 112 and 10~ are aligned and retain a wood~uP~ key to prevent relative rotation. In oxder to install .the keyway 8hifter o~ the present invention, the woodru~f key is ~irst removed thus allowing rotor 107 to he rotated relative to shaft 108. ~rotrusion 110 of keywa~ shifter 98 is first inserted in keyway slot 112, rotor 107 is then rota~cd wi~h xespect to shaft 1~8 to brin~ keyway 106 into alignment with protrustion 104 of keyway shifter 98 thus allowing section 102 of keyway shifter 98 to engage the upper surface 114 of : :~
rotor 107. A jam nut.115 is then tigh.tened down over keyway shifter 98 and rotor 107 thus securing th.em to sh.~t lQ8.
It is possible in certain applications that the key~tay slot on the rotor may not extend completely through to the top surface thereof or the keyway slot on the crankshaft may not extend to the upper end of the shaft. This situation usually occurs whe~ the keyway slots have been formed by a milling machine. In either case, in order to install the keyway shifter of the present inventio~,.it will be necessary to extend the keyway slot so as to provide openings for ~he keyway shifter to seat in. This ~ay easily be done hy filing of the rotor or crankshaft.
Refcrring now to Figures 9 and 10, the operation of the present invention will be described in detail. A
coil assembly is shown schematically at 128 o~ Fl~u~e 9. In operative positionl the coil and appropriate st~tor structuxe described above would be securely mounted to the en~lne adjacent ~he rotor oarrying the magnetic ~ieId ~eneratln~ ~:
.
, ~ .
1 5 r~
.
~r ~.
~ b9~77 - mcans. An ignition module, ~s shown schem~tically ~t 130 o~
Figure 9 is mounted on the engine in an~ conVenient loca~ion and ls eleckrically coupled to the c:oil asseJnbl~ b~ conductors 132 and 134. Both the coil assembl~ and i~nition modulc J
have means 136 and 138, xespectivel~, for cre~tin~ ~n electrical eonnection to ground which, in this case, may be the engine ~tself. Additionally, coil assembly 128 has a hiyh volt~ge conductor 140 for conducting the ;ignition volta~e to the spark plug.
~- As the rotating m~gnetic field, carried by the rotor, passes in close proximity to the stator co~e, it induces therein a time varYing magnetic ~lux, ~s this ~lux inereases in magnitude, it induces a voltage in the auxiliary eoil which causes a current to ~low fxom the coil assembly along conductor 132 through diode 142 and conductor 144 to eapacitor 146 creating a positive charge thereon. Diode 148 is eonnected between conductor 132 and ground 138 and serves to dampen negative spikes induced in the auxiliary coil.
The voltage~ induced in the auxiliary coil, as this ti~e varying magnetie field increases in intensity, is plotted against time in gr~ph 150 of Figure 10 with maximum intensity being achieved at point 152. Graph 154 shows the voltage vs. time plot o~ the charging of capacitor 196 in response to the induced voltage on the auxiliary coil. As shown graphieally, capacitor 146 achieves a maximum charge ~t point 156 which corresponds in ti~e to the ~aximum rate of ~hange of flux intensity passing through the st~to~ coil.
hs diode 142 only conducts in one direction, the chaxge on capacltor 146 wlll be maintained.
.
; - -16- ;
. . .
- ~ :.. . : : ..
:: ~ : . . .
- : . . -:
:...... : , . .
~9~77~
A switch moans 158, such ~s a silicone contxollcd rectiier ~SCR), is pxovided between capacito~ 146 and pxima~y conductor 13~ connected to the prima~y coil winding.
A xesistor 160 ~nd a diode 162 axe c:onnected in p~rallel between the cathod~ 164 and gate 166 o~ SCR 158. Diode 162 serves to protect SCR 158 from positiVe t~ansients lnduced in the primary coil winding during the chargin~ o~ capacitor 146.
As the rotating ma~netic ~ield begins to moye out . . .
of alignment with the statox, the ~agnetic flux followin~
thexethrough begins to drop. This then causes a negatiye voltage to be induced in the primar~ coil, thus c~using a ~urrellt to ~low throu~h conductor 134. This will then cause gate 166 of SCR 158 to be positively biased with respect tQ
cathode 164, thus causing SCR 158 to become conductive.
This is shown pictorially on graph 168 of Figure 10, which pIots voltage vs. time as measured across the primary winding.
When SCR 158 becomes conductive, capacitor 146 will dis-charge through SCR 158 and through primary coil 170. As ;~ the primary and secondary ignition coils are magnetically coupled, the discharge through primary coil 170 cooperatively with the time varying magnetic flux induces the ignition spark generating vo'tage in secondari~ coil 172.
In order to maintain maximum operating e~ficiency o~ the engine~ it is important to insure capacitor 146 will repetitiYely fire at precisel~ the same time rel~tive to the an~ular position o~ the cr~nkshat with as little ~ariation as possible over the entire b~oad speed r~nge o~
the en~ine. It has been ~ound through experiment~tion that ; ' ' .. ~, , -I
.:: ~ . .
~9~77~
J
the ignition modul~ circuit o~ ~igure 9 in coope~Atlon wlth the degxee o~ magnetic~couplincJ of the l~nition ~nd auxiliary coils and thei~ polarity ~elationships plus the lack of frequency sensitivit~ in the SCR gate network produc~
gxeater timing stability than found in conventional ignition s~stems.
In certain applications,.it is desixable to have ,the sp~rk timing retarded during starting of the engine : ~ut,,when the engine is at operatiny speed, it becomes necessary to advance the ignition timing in order to obtain m~ximum engine efficiency, Accordingly, it is desira,ble to pxovide means which would automatically ~ccomplish this with-out increasing the costs of the conVersion contemplated herein.
'Fagure 11 shows a stator structure 174 s.imila~
to,that shown in Figure 2 but incorporating a further ,modification which automatically advances.the ignition ' timing'as engine speed increases. Stator 174 is identical . to stator 42 with the exception of lower leg portions 176 and 178 respectively. Leg portion 176 is divided into two spaced apart segments 180 and 182. Segment 180 extends ' laterally and lorgitudinally ~rom the main portion of leg 46 and is slightly longer th~n segment 182 so as to provid~
a smaller air gap betwcen the stator and.rotor when installed on an engine. Both segments h~ve convex end surfaces 184 and 186 as previously described or stator 4 2 of Figu~e 2.
Similarly, leg portion 178 is diyided into twa se~ments 188 and 190. Se~ment 188 extends later~ nd lon~itudinally . ~om the main portion of leg 44 in the s~me direction a5 ~egment 180 and is also slightly.longs~ tha,n seg~ent 190.
' - ;: -: , :
- : . . :~: : ;:: .. :: . :........ .. :
:: . : . . :. ~ . . . .: i :;
3L1~9~7~
Both segments 188 ~nd 190 have convex end surf~ces 192 and 194 similar to those previously described. There is thus provided a slow speed flux path co~prising se~ment lB8, leg 44, interconnecting portion 50, le~ 46, ~nd segment 180, and a high speed flux path comprising segment 190, leg 44, interconnecting portion 50, leg 46 and seg~ent 182.
At low speed operation, the trailing segments 180 and 188 provide a significantl~ greater operating flux.for inducing the ignition voltage in the coil due to -the relatively smaller air gap relative to that created b~ segments 182 and 190. As these sections are shifted slightly in the dlrection of rotor rotation relative to the ~ain leg of the stator, the ignition timing during high speed operation is advanced relative to the ign~tion timing during low speed operation. As the operational speed increases, the magnetic flux provided by the leading pair of stator leg segments 182 and 190 will induce an increasing].y greater voltage in the coil due to the increased r~te of change of the magnetic field. This ignition voltage will necessarily be advanced relati~e to that induced from the flux provided by the traiIing ssgments 180 and 188 due to the relative position o~ the sections. Thus,.at a suf~iciently hlgh operating speed, the time varying ~agnetic flux provided by the leading pair o stator le~ seg~ents 18~ and 190 will induce a voltage in the ignition coil sufficiently large to .
cause the associated capacitiVe discharge ignition circuitry, ~.
as described above and in the two prev~ousl~.re~exenced applications, to operate. There ls thexeby created means r Which will automat~cally cause.the ignition timing to advance .
-19- .
.. ..
7i9~
ln r~sponse to increased engine speed. The positi~ning o~
the leg secti~s relativc to e~oh othc~ ~nd xel~tive to the angle of rotation of the rotor will contxal the de~ee o~
timing advance or retardation.
Figuxe 12 shows a st~tor stxuctu~e 196 similar to that of Figure 1 but having a further modi~ication si~il~x to that previously described fo~ stator 174 o~ Fi~ure 11 incorporated thereon.- Stator 196 h~s lower leg po~tions 1~8 and 200, e~ch of which is divided into two segments 2Q2, 204, 206 and 208 t respectively. As pre~iously de,sc~ibed with reference to ~igure 11, segment 202 is slightly longer than segment 204 and segment 206 is slightl~,'longe~ th~n se~ment 208 and all segments haye conVex end surfaces thereon., The operation of this modlfication is identical to tha~ des~
cribed with reference to stator 17~ ~f Figure 11.
Figure 13 in like manner sho~s a stator structure 210 similar to that of Figure 3 but incorpor~ting thereon the modi~ication similar to that previously described for stators 174 and 196 of Figures 11 and 12, respectively. Stator 210 has lower leg portions 212 and 214, each of which is divided into two segments 216, 218, 220 and 222, respectively, all of which have convex end surfaces. Segment 216 is slightly shorter than segment 218 and se~ment 220 ls slightly shorter than segment 222. The operation of this m~dification is identical to that previously described ~ith ~e~erence ~o ~tator 174 of Fi~ure 11, a,low speed ~lu~ p~th bein~ defined by segment 218, leg 6~, interconnecting po~tion 70, le~ 68, ~nd segm~nt 222 and a high s~eed flux path bein~ de~lned b~
.
~0-~
:........................ . . .
., ~ .
:: ~ '.,::. : .: . :.
:: .. ,.. - ~
77~
~egmcnt 216~ le~ 66, inte~conncctin~ po~tion 70~ leg 68, and segm~nt 220, It should also be noted th4t this ~odiica-: k~on may bc incorporated into the deslgn o~ st~tor 94 o~
Figure 4 in like ~anner as descxibed with re~exence to stator 210.
Reference is now made to Figures 14 throu~h 16 in which-is illustrated the sequence of operations by which : . an owner of an existing machïne ha~in~ an iternal combustion engine with a convent.ional i~nition syste~ may ayail himself of the advantages of the capacitive discharge ignition system o~ the present invention. In Figure 14,.there is illustrated an internal combustion en~ine 224 which was manufactured with a conventional i~nition system. The i~nition system comprises a rotor 226 havin~ a north. ma~netic pole 228 and a south ma~netic pole 230 spaced a short dis-tance apart and disposed on the peripheral.surface of rotor 226. The original stator 232 and coil assembly 234 is mounted on engine housing 236 i~mediately adjacent rotor 226 through the agency of bolts 238 and 240.
In order to convert this ignition system to that . of the present invention, the existing stator 232 and coil assembly 234 is removed. As shown in Figure 15, there is then exposed two mounting pads 242 and 244, which cooperate with bolts 238 and 240 to secure the stator and coil assembly.
A stator 248 havin~ a coil assembly 246 mounted thereon, both in accordance with the p~esient inyention, is the~ securcd to the mounting pads 242 and 244 through the agency o~ bolts 238 and 240 p~ssing through e}ongated g `
"', .', ~99~7~77 .
apcrtures 239 and ~41. These olon~at~d apcrtures ~ll.ow ~tator 2~6 to then be positioned to a~ d the px~determined air gap between it and rotor 226, wld bolts 2~8 and 240 are then tightened thus securing stator 298 in position. The ignition module previousl~ described may be mounted in any convenient location on the machine and is electrically connected to coil assembly 246 b~ means of conductors 250, 252 and 254. ~ltexnatively, the stator and coil assembly ~ay be fabricated with the ignition module bein~ integral thereto thus further simpli~ying the conversion.p~ocess throu~h the elimination o~ the electrical connections. High voltage conductor 256 is connected to the spark plug thus completing the installation of the ignition s~stem of the present.invention. It should be noted that the ignition timing has been adjusted by means of the construction of the new stator 248, as may be readily seen in a comparison of Figures 14 and 16.
A similar conversion of an internal combustion engine of a chain saw is illustrated in Figures 17 thro~gh 19. Figure 17 shows the en~ine.258 having a conventional ignition system comprising a stator 260 secured to engine 258 by volts 262 ~nd 264, a coil assembly 266 mounted on stator 260, and a rotor 268. Rotor 268 has ~ north ma~netic pole and a south magnetic pole spaced sli~h.tl~ apart ~nd disposed on its outer periphery ~o~ ~eneratin~ the time varying magnetic ~lux in stator 260.
.
In installing the stator and coil assembly o~ the . present invention, the existing stator 260 ~nd cQil ~ssembly 26~ are removed from engine 258 by removal o~ bolts 262 and ~ ' ' .
.
:
. . ~22-~ . .
.. . . _ _ :
. .
::, - : " : ~ . :
- . . . .. ..
~9~
264. Thus thcrc is exposed mounting pads 270 ~nd 272 disposed on enyine 258 as best 5een in Figure lB. The new stato~ 274 and coil assembly 276 o~ the p~esent inyention are then mounted on engine mountin~ pads 270 and 272 through the ayency of bolts 262 and 264, St~tor 274 is then positioned to afford the proper air gap between it and.rotor 268 and ~olts 262 and 264 a~e tightened, thus securing statcr 274 in operative position~ The iynition module previously described is then mounted in any convenient.location and electrica}ly connected to coil assembly 276 or alternatively may be integral with the stator and coil assembly as pre-~iously described. It will be noted b~ a comparison of Pigures 17 and 19 that the ignition timing has been shi~ted approximately 18 through the use of the stator structure of the present invention, thus eliminating the need for any structural modification of the engine itself.
~here is thus disclosed herein means by which . .
. . any individual having a very few basic tools may easily convert the existing ignition system of his lawnmower or the like to the capacitive discharge ignition system of the present invention. As is apparent from the above description r there is provided means by which the difference in ignition timing of the capacitive aischarge ignition system relative to the conventional ignition system may be compensated for so as to maintain the ignition timing o~ the en~ine.
The absence of any necessity to pexfor~ delicate machinin~
operations or the need for any complex engine ~odific~tions makes it possible to completely elimin~te the need for any knowledge whatsoever o~ machinery operations o~ engine .
. -23-..
~ , . -,, . ~ - ~
, . .: . ~
' ,'' -i ~ ~ , '' :
: , ~ ~ 9 9!7 ~ 7 ignitlon system theory by the owncr. Fu~thcr~ ag the re-placemcnt of parts ls minimized, the individual ~a~ achieve the advantages inherent in a capacitive dischar~e ic~nition system at a relatively small investment of money and time.
It is to be undcrstood that the forec~oing des-cription is that of preferred embodiments of the in~ention.
V~rious changes and modifications ~a~ be made without departing from the spirit and scope of the inventiQn as de~ined by the appended claims.
, ~ , .
, . . .
~, -~24-, .
, . , "~
.. . .
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A capacitor discharge system for an internal combustion engine comprising a permanent magnet means rotated about a circular path in synchronism with the operation of said engine, a core of ferromagnetic material mounted adjacent said circular path and having one portion providing a path for the varying flux generated by the movement of said magnet means past said core, a charging winding and a transformer having primary and secondary windings mounted on said one core portion, said charging winding being offset from said primary and secondary windings radially with respect to said circular path, said charging winding and primary winding being wound on said one core portion such that the voltages induced therein by said varying flux each includes half wave voltages of opposite polarity, a charging circuit including a capacitor connected across said charging winding and a diode poled to pass half wave voltages of one polarity for charging said capacitor and maintaining said capacitor charged when the voltage generated in said charging winding is opposite said one. polarity, circuit means connecting said capacitor with said primary winding for discharging said capacitor through said primary winding and including an electronic switch means having anode, cathode and control electrodes, the anodecathode junction of said switch means interconnecting the ends of said charging winding and said primary winding which are simultaneously at the same polarity, said control electrode being connected to the other end of said primary winding, the polarity of which is opposite said same polarity, said switch means being nonconductive during the charging of said capacitor by said one polarity of the voltage generated in said charging coil and being rendered conductive by voltage generated in the primary winding opposite said same polarity whereby said capacitor is charged during one complete half cycle of voltage generated in the charging coil and discharged during the next half wave voltage generated in said charging winding.
2. A capacitor discharge system for an internal combustion engine as set forth in claim 1 in which said control electrode is connected by circuit means to the ends of both of said primary winding and charging winding opposite to the ends of these windings interconnected by the cathodeanode junction of said electronic switch means.
3. A capacitor discharge system as set forth in claim 2 in which said circuit means connecting the control electrode to said primary and charging winding includes a resistor.
4. A capacitor discharge system as set forth in claim 3 in which said electrode switch means is a silicon control rectifier and the control electrode thereof is the gate of said rectifier, said gate electrode and the ends of said charging winding and primary winding opposite said same polarity being connected to ground potential.
5. A capacitor discharge system for an internal combustion engine comprising a permanent magnet means rotated about a circular path in synchronism with the operation of said engine, a core of ferromagnetic material mounted adjacent said circular path and having one portion providing a path for the varying flux generated by the movement of said magnet means past said core, a charging winding and a transformer having primary and secondary windings mounted on said one core portion, said charging winding being offset from said primary and secondary windings with respect to said circular path, said charging winding and primary winding being wound on said one core portion such that the voltages induced therein by said varying flux each includes half wave voltages of opposite polarity, a charging circuit including a capacitor connected across said charging winding and a diode poled to pass half wave voltages of one polarity for charging said capacitor and maintaining said capacitor charged when the voltage generated in said charging winding is opposite said one polarity, circuit means connecting said capacitor with said primary winding for discharging said capacitor through said primary winding and including an electronic switch means having anode, cathode and control electrodes, the anodecathode junction of said switch means interconnecting the ends of said charging winding and said primary winding which are simultaneously at the same polarity, said control electrode being connected to the other end of said primary winding, the polarity of which is opposite said same polarity, said switch means being nonconductive during the charging of said capacitor by said one polarity of the voltage generated in said charging coil and being rendered conductive by voltage generated in the primary winding opposite said same polarity whereby said capacitor is charged during one complete half cycle of voltage generated in the charging coil and discharged during the next half wave voltage generated in said charging winding.
6. A capacitor discharge system for an internal combustion engine as set forth in claim 5 in which said control electrode is connected by circuit means to the ends of both said primary winding and charging winding opposite to the ends of these windings interconnected by the cathodeanode junction of said electronic switch means.
7. A capacitor discharge system as set forth in claim 6 in which said circuit means connecting the control electrode to said primary and charging winding includes a resistor.
8. A capacitor discharge system as set forth in claim 7 in which said electrode switch means is a silicon control rectifier and the control electrode thereof is the gate of said rectifier, said gate electrode and the ends of said charging winding and primary winding opposite said same polarity being connected to ground potential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA374,561A CA1131294A (en) | 1976-02-23 | 1981-04-02 | Ignition system |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US66012276A | 1976-02-23 | 1976-02-23 | |
| US660,122 | 1991-02-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1099777A true CA1099777A (en) | 1981-04-21 |
Family
ID=24648235
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA268,205A Expired CA1099777A (en) | 1976-02-23 | 1976-12-17 | Ignition system |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS52102938A (en) |
| CA (1) | CA1099777A (en) |
| MX (1) | MX143027A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU528040B2 (en) * | 1979-04-13 | 1983-04-14 | R.E. Phelon Company, Inc. | Capacitor discharge breakerless ignition system |
| JPH0431866Y2 (en) * | 1986-12-12 | 1992-07-30 |
-
1976
- 1976-12-17 CA CA268,205A patent/CA1099777A/en not_active Expired
-
1977
- 1977-02-04 MX MX16793177A patent/MX143027A/en unknown
- 1977-02-21 JP JP1801877A patent/JPS52102938A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS52102938A (en) | 1977-08-29 |
| MX143027A (en) | 1981-02-10 |
| JPS6143549B2 (en) | 1986-09-27 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |