Note: Descriptions are shown in the official language in which they were submitted.
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Background o~ the Invention
; This invention relates to an alternator apparatus for
powering a capacitor discharge ignition system for internal
combustion engines and auxiliary electrical equipment and partic-
ularly to such apparatus for a two cylinder engine designed for
application to outboard motor units and the like.
. Capacitor discharge ignition systems have been developed
for application in internal combustion engines and have partic-
ularly been employed in connection with propulsion devices such
as outboard motors, snowmobiles, motorcycles and similar vehicles. :
Generally, the capacitor discharge ignition syst~ms employ
one or more firing capacitors. Suitable control switch means
~ such as controlled recti~iers connect the capacitor or capacitors
: to the spark plugs for discharging of the capacitor and firing
of the engine. The alternator is constructed and connected for
charging the capacitor and for generating the triggering pulses
; for firing the controlled rectifiers.
The ignition system, particularly or smaller outboard
: engines and the like, is aclvantageously powered from an engine
driven alternator unit. Space limitation generally re~uires a
relatively small, compact, lightweight construction. The
alternator unit may be conveniently incorporated into the flywheel
structure of the engine. The flywheel is formed as a cup-shaped
member secured to the engine shaft with a rotor means secured
within the skirt. A stator coil assembly is mounted in fixed
relation to the engine with appropriate coils coupled to the
rotor means. The rotor means includes suitable permanent magnet
members with spaced flux reversal points or portions to provide
appropriate coupling to the stator assembly ~.or generating appro-
priate charying power to the ignition capacitor and appropriatetrigger signals for discharging thereof at the proper time.
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In one system for a two cylinder engine, a pair o.~
ignition capacitors are connected to be alternately charged from
a charging coil unit and alternately discharged from a separate
trigger coil unit.
In many engine driven propulsion devices, auxiliary
electrical devices such as lights, starters, a battery and the
like are provided. An alternator unit is preferably constructed
and connected to provide a rectified voltage output for charging
of the battery or an A.C. ~oltage output for operating lights.
Although separate alternator units may be provided, a single
integrated assembly is desirable, particularly where severe space
limitations are encountere~, such as in small outboard motor units.
Although compact alternator units have been suggested,
the location of the various functioning coils within a common
compact and integrated cons-truction tends to create cross-coupling
between the several signal generatlng systems and in particular
may cause improper or undesired ignition. Althouyh ~uch s~stems
do, thereforé, provide impro~e~ engine operation, a high degree
o~ reliahility and maximum e~fici.enc~ o~ operation is o~ten not
obtained, particularly in the small, compact constructions.
Summary of the Present Invention
The present invention is particularly directed to a
compact~ lightweight dual alternator unit including a common rotor
support and having a flrst ignition section or alternator means
for powering the i.ynition circuit and a second power section or
alternator means mounted immediately ad]acent the first section
and constructed for providing auxiliary power suitable for battery
charging or A.C. lighting.
The invention in one broad aspect pertains to a rotating
power source having a rotating input adapted to be connected to
the output drive of an internal combustion engine and producing
power for firing of the engine ignition means. The power source
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includes a rotor means having iynition magnet means secured to
the periphery khereo~ and a power magnet means i5 secured to
the rotor means adjacent the ignition magnet means and is
axially spaced of the ignition magnet means. The power magne-t
means includes a substantially greater number of magnets than
the ignition magnet means. An ignition winding means is
mounted in alignment with the ignition magnet means and de~elops
a series of ignition power pulses having a speed related frequency.
A power winding means is radially aliyned with the power magnet
means and has a substantial number of poles and creates an
alternating current output having a substantially higher frequency
than the speed related frequency of the power pulses, the frequen-
cy being determined by the number of power magnets and related
to the frequency of the ignition signal. The number of power
magnets is selected and arranged relative to the ignition
winding such that leakage flux from the power magnet means
passing through the ignition means produces a symmetrical
superposing of a power frequency signal on the ignition power
pulses in the ignition winding means.
Another aspect of the invention comprehends an alter-
nator apparatus for a capacitor discharge ignition circuit
having an ignition capacitor connected in a discharying circuit
including a triggered switch means and for a separate powe~ load.
The apparatus includes a rotor means having first ignition rnagnet
means having a plurality of circum~erentially spaced magnets for
providing an output for operation of the ignition circuit and a
second power magnet means having a different and greater plural-
ity of circumferentially spaced magnets for producing an alter-
nating current po~er output. A common rotating support has an
axis of rotation and has the first and second magnets means
mounted thereon in axially close spaced relation. Ignition
charging and trigger coil means are secured in radial alignment
with the first ignition magnet means to produce time spaced trigger
signals and are coupled by leakage flux to the second power magnet
means. A power coil means is secured in radial alignment with
the second power magnet means. The second power magnet means in-
cludes the plurality of magnets selected to produce leakage flux
coupled to the ignition charging and trigger coil means creating a
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symmetrical ripple voltage in the trigger coil means and thereby
maintaining symmetrical trigger signals from the trigger coil
means and thereby a symmetrical ignition timing characteristic.
More particularly, the alternator unit includes an
annular rotor having first and second closely, axially spaced
magnetic field means. A stator assembly is mounted in relatively
fixed relation within an annular rotor, and includes an ignition
coil unit including a charging and trigger coil means aligned
with the first magnetic field means and an auxiliary power wind-
ing in alignment with the second magnetic field means~ Theignition coil unit may include two or more charging windings and
a single trigger winding for charging of the capacitor means and
gating of the switch means for firing of each cylinder. The
auxiliary power magnet and winding includes a substantial number
of magnetic poles and coils to produce a signi~icant power output
of a generally high frequency compared to the ig~itio~ ~ir~ng
rate. For example, in one embodiment ~or a two cvlinder engine
a fourteen pole field and a five coil wind~ng produced an alter-
nating output which, when rectified, was at a level of 50 watts
of D.C. power or 60 watts of A.C. power unrectified~
The magnetic poles of the auxiliary section are selected
such that leakage flux from the auxiliary section generates a
ripple voltage in the trigger coil means of the ignition section
which, in accordance with one significant aspect of this invention,
has a symmetrical effect on the trigger signal to maintain good
timing symmetry between the several cylinders and does not
function in such a manner as to lock a gated or triggered
control switch such as a control rectifier into conduction.
In a novel embodiment of this invention for a two cylinder
engine, the ignition circuit generally includes first and second
ignition capacitors connected to the charging coil means through
a suitable rectifying diode network and to the spark plugs in
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series with a discharge switch suc~h as a controlle-l rectl~ier,
such as shown in U.S. Patent 3,937,200. A trigger coil means
is connected to the gate means for alternate discharging of the
capacitors to alternately ~ire the cylinders. The capacitor
charging rotor includes two permanent magnets secured within an
annular support such as the 1ange o~ a cup-shaped flywheel and
each extends for approximately 180, with small neutral zones or
effective air gaps between the ad~acent ends. The two magnets
are radially and oppositely polarized to ~evelop a working gap
from the magnet to the coil stator in a radial direction. The
stator includes a core having a pair of ignition capacitor
charging coils mounted on coxe poles spaced by 180. A trigger
coil is mounted between t.he charginy coils and circumferentially
movable to adjust the coupling to the neutral zones of the
ignition magnets for control of the timing. As the flywheel
rotates, opposite polarity pulses are generated in the
charging coils every 180 of crankshaft rotation ko alt~rnately
charge the capacitors, and similarly opposite polari,ty trigger
pulses, separated by 180, are ~enerated to di.scharcJe a prevlou~ly
charged capacitor. The trigger coil was mounted ~'or about 60
of iynition timing adjustment. Even with the maximum advance,
essentially 270 of crankshaft rotation is available for charging
of the ignition capacitors, which provides ample time for
charging of the ignition capacitors to the maximum voltage level
throughout the normal range of speed and timing or an outboard
motor engine. The power magnet poles are equicircumferentially
located in the second section o the rotor, with radial and
alternate opposite polarization o the poles. The power winding
coils are grouped together and wound on projecting poles o an
arcuate core segment with poles and coils spaced for alignment
with the correspondingly spaced magnetic poles of the second fleld
means to form an arcuate assembl,y. The two pole ignikion field is
secured coaxially of the power ~ield wi-th the two neutral zones
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align~d between, and preferably centrally of, two adjacent poles
of the power field. In a particular embodiment, a fourteen pole
rotor and a five coil stator were provided. The fourteen poles
induced a symmetrical signal in the trigger coil ~hich maintained
the symme-trical timing. A significant feature of this invention
is the adaptability to production line manufacture of manual or
non-electric models without a power section and the electric
models by proper magnetization of one or two levels. Additionally,
` a manual and/or non-powered model outboard unit may be changed
by providing of a klt including the dual stator assemblies and
magnetization of the power field section. Applicant has found that
the present invention provides a reliable and relatively inexpen-
sive dual alternator unit for producing power to a capacitor dis-
charge ignition system and operating power to auxiliary equipment
in a compact assembly.
Brief Description of~ the Drawings
The drawings ~urnished herewith illustrate a preferrect
construction of the present invention in which the above
advantages and :Eeatures are clearly disclosed as well as others
2Q which will be readily understood from the ~ollowing description
of such embodiment.
In the drawings:
Fig. 1 is a diagrammatic view of a two cylinder internal
combustion engine such as employed in outboard motor unit and con-
structed in accordance with the present invention with a dual
alternator unit having an ignition section and a power section;
FigO 2 is a side view o~ the alternator unit with parts
broken away and sectioned;
Fig. 3 is a vertical section taken generally on line 3-3
of Fig. 2 and with rotor poles illustrated by the conventional
north (N) and south (S) polarity designation;
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Fig. 4 is a bottom vie~ taken generally on line 4-4
of Fig. 1, with the rotor poles o* the power section identified
as in Fig. 3;
Fig. 5 is a schematic circuit diagram of the elec~
tricalsystem and the dual alternator unit of Figs. 1-3; and
Fig. 6 is a graphical illustration of the output of
-the yenerator means of Figs. 2-4.
~escription of Illu-strated Embodiment
Referring to the drawings and particularly to Figs. 1,
the illustrated embodiment of the present invention includes a
dual alternator unit 1 directly coupled to a two cylinder
engine 2 mounted as the powerhead of an outboard motor unit 3.
As shown in Fig. 5, the dual alternator unit 1 includes first
output leads 4 connected to an ignition unit S for firing of the
engine and second output leads 6 connected to auxiliary e~uipment,
shown as a battery charging system including a rectifier 7 or a
regulator 8 connected to a battery 9 as well as other auxiliary
equipment. The ignition unit 5 is preferably a capacitor dis-
charge system including a pair of ignition capacitors 10 and 11
which are alternately and cyclically charged as more fully
developed hereinafter and which are alternately dlsaharyed to
the spark plugs 12 and 13 for appropriate ~iring of twe
cylinders 14 and 15, once eaah cranksha~t revolution. The dual
alternator unit 1 is loaated within a cup-shaped flywheel 16
immediately adjacent to the engine block 17 to provide a
compact assembly particularly adapted to outboard motor units
and the like.
Generally, in the illustrated embodiment, the GUp-
shaped flywheel 16 includes a central hub 18 appropriately
3Q keyed or otherwise fixedly secured to the engine crankshaft 19.
The alternator unit includes an ignition generator section 20
and a power generator section 21 located in axially spaced
relation within th~ flywheel 16 which functions as a common rotor
support. The ignition generator section 20 includes a stator as-
sembly having charging coils 22 connected to charge the,capacitors
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10 andll, and a triycler coil ~3 connected to alternatelyactuate
switch means shown as con-trol rectifiers 24 and 25 which are
connected to discharge the capacitors 10 and 11 through related
pulse transformers 26 and 27. The spark plugs 12 and 13 are
connected across the secondary of the pulse transformers 26 and 27.
The invention is particularly directed to the construc-
- tion of the alternator unit and a preferred embodiment is more
clearly illustr~ted in Figs 2-4.
The cup-shaped flywheel 16 includes an outer base
portion 28 integrally formed with the hub 18 and an outer, annular
skirt 29 in accordance with a generally conventional shape. The
power generator section 21 is located immediately adjacent the
inner end o~ the skirt 29. The power generator section 21 in-
cludes a rotor 30 formed by a mer~er aligned wi-th a stator
asser~ly 31 which includes power w.inding or coils 32 connected
in series to the pairs of leads 6. The ignition generator section
20 similarly includes a rotor 33 formed hy a permanent magnet
member aligned with a statlonary stator assel~ly 34 including the
charging coils 22 and the triyger coil 23.
In the illustrated embodiment, the ro-tor magnet member.s
may be formed in single magnetic strip, or by similar axially
spaced strips, ~y appropriate polarization in the plane of the
respective sections 20 and 21, and to the opposite sides of
neutral zone or plane 35 between such sectionsO The magnet strip
may be formed of a suitable magnetic plastic/ such as 3MTM
Plastiform material manufactured and sold by Minnesota Manufacture
and Mining Company of Minnesota, and adhesively bonded to skirt
29 if the flywheel is formed of a mac3netic steel. If not, a
separate magnetic strip, not shown~ would be interposed to serve
as a flux return path~ The magnetic fields of the power sect.ion
21 and ~he ignj.tion section 20 are closely spaced. The power
section 21 gen~rates a relatively high frequency alterna-ting Eield
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which, due to the proximi.ty o~ the ~tator ~ection~, will induce
a ripple volkage in the trigger coil 23. The magnet unit of
section 21 is specially constructed to induce a sy.~netrical signal
in coil 23 to maintain proper timing.
More particularly, in the illustrated embodiment of the
invention, the outer vertical level magnet strip 33 forming a
part of the ignition generator section 20 is spot magnetized,
radially of the rotor, t-o define two distinct, circumferential
magnets as shown diagrammatically at 36 and 37, in Figs. 4 and 5.
The magnets 36 and 37 are oppositely and preferably radially po-
: larized throughout their length to define a pair of flux reversal
locations or junctions 38 and 39 separated by 180. The junction
38 and 39 may include small neutral or non-magnetic portions or
even an air gap where separate magnet members are employed.
The stator unit 34 Qf the ignition generator section 20
includes a semi-circular laminated core 40 having end pole~
40a, on which charging windings or colls 22 are waund.
The core 40 is semi-circular such that the coils 22 are
spaced from each other by 180 ancl selectively coupled to the flux
reversible junctions 38 and 39 of the permanent magnets 36-370
The core 40 is mounted to a support hub 41 having a central open~
ing through which the crankshaft 19 freely passes. The support 41
is suitably bolted or otherwise attached to the engine block to
support the core 40 in fixed aligned relation to the annular mag-
netic means formed by the magnets 36 and 37.
The trigger coil 23 is wound on a core 42 which is
mounted for angular orientation hetween the stator poles 40a for
sequential coupliny to the flux reversal junctions 38 and 39 such
as shown in the U.S. Patent 3,937,200 which issued to Sleder et al
on February 10, 1976. A trigger signaL is thus generated between
theSUCCeSS1Ve charging pulses. Successive triggering signals are
of opposite polarity and in the illustrated embodiment function to
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a].ternately fire recti~ier 24 and 25 ~or iriny o;~ the two
cylinders 14 and 15 of engine 2.
As shown in Fig. 5, the charging coils 22 are connected
in series aiding between leads 43 and 44, the latter being
connected as a common ground. Lead 43 i5 connected to the top-
side of capacitor 10 by a blocking diode 45 and the opposite side
of capacitor 10 is connected by a diode 45a to ground and thus to
lead 44. The voltage output of the windings 22 is thus airectly
connect~d to charge capacitor 10 when lead 43 is positive. Lead
44 is similarly connected to the topside of capacitor 11, via a
diode 46, and lead 44 is connected to the bottom side by a diode
46a, to provide charging current to the ignition capacitor 11,
with the output polarity of the coils reversed. The flux reversals
of the junctions 38 and 39 are in opposite directions with respect
to the coils 22 to generate opposite polarity pulses and thereby
alternately charge the capacitors 10 and 11, once each complete
revolution of engine.
The triggex coil 23 produces a contxolled discharge of
; the fully charged capacitors 10 and 11, and, in particular, is
preferably and movably mounted for positioning within the flywheel
16 in any known or desired manner, to develop appropriate trigger
pulses reilated to the position of the piston relative to top dead
center for retard or advance fixing. Coil 23 is shown mounted in a
suitable housing and having a mounting ring which is coupled to a
throttle linkage, not shown, such as disclosed in the previously
identified U.S. Patent 3,937,200.
Referring particularly -to Fig. 5, in the illustrated
embodiment of the invention the ignition also includes a trigger
stablizing circuit 47 for firing a rectifier 24 and 25. A separate
trigger or pilot switch shown as controlled rectifiers 48 and 48a
is provided for controlling the discharging of the capacitors 10
and 11. The rectifiers 48 and 48a have their gate to cathode in-
puts connected in series with the gate to cathode inputs of the
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main rectlfier 24 arld 25 to turn on the corresponclin~J rectifier.
A firing capacitor 49 in sexies with a comlrlon resistor 50 is
connected by rectiflers 48 and 48a to rapldly drive rectifiers
24 and 25 fully on. Capacitor 49 is charged from capacitors 10
and 11 through charging resistors 51 and 52 and a common parallel
resistor 53~ The resistance of the resistors 51 and 52 is high to
prevent excessive dischar~e of the main firing capacitors 10 and
11 and to insure the holding curren~ decreases sufficiently to
turn off the pilot rectifier 48 and 48a after capacitor 49 dis-
charges. The capacitor 49 is discharged throuyh pilot rectifiers
into the gate to cathoda junction of the main rec~ifier 24 or 25
to circuit reference. This turns on the rectifier 24 or 25 and
rapidly discharges the energy of related igni-tion capacitor 10
or 11 through the pulse transformer 26 or 27 and the corresponding
spark plug 12 or 13 for firing of the engine. Protective diodes
54, 58 are connected across the rectifiers and transformer primary.
The gates of the recti~iers 48 and ~8a are aonnecte~d to
the opposite ends of khe txigger coil 23 by trigger leads 55 and
55a and a s~rie9 connected steering diocle-resisto,r 56. The capaci-
t:ive resl~tive hias and stabiliæing network 47 is connected across
the trigger coil leads. The network 47 includes a bias stabilizing
capacitor 57 to insure a preset, fixed, firing time independent
of speed, with the advance and retard setting oE the trigger coil
23 separately controlled through the throttle setting. ~ reverse
bias limiting voltage dividex branch 58 limits the voltaye between
trigger periods. This stabilizes the ignition an~le generally as
taught in U.S. patent 3,805l759.
In Fig~ 5, when the trigger lead 55 is positivel the
pulse of coil 43 flows through the lead 55 t diode-resistor 56,
gate-to-cathode of rectifiers 48 and 24, capacitor 57 and a
return resistor 59. When lead S5a i~ positive a similar current
pulse turns on rectifiers 48a ~nd 25 for discharging of capaci-
"~ ~ 1 1
112C~3~
tor 11.
The charging and triggeriny circuit includes a common
or reference line 60 connected to ground through the diode 45a~
RFI suppression capacitors 61 and 62 are connected from the anodes
of rectifiers 24 and 25 to the engine block or ground, as shown,
The resistors 59 and 59a load the pul.se to maintain stable
timing in the event low leakage impedance occurs between the
trigger leads and ground.
The ignition generator section thus generates a charg-
ing pulse and a firing pulse in time spaced sequence and in a
repetitive manner. Such ignition signals for each cylinder 14
and 15 are generated once each engine revolution ~or proper
firing of a two cylinder, two cycle engine. The particular time
of firing is controlled by the physical positioning of the
trigger coil 23. The floating or ungrounded output of coil
23 thus provides opposite polarity half cycles or pulses which
are operative to alternately fire the two cylinders of engin~ 2.
The cylinders are fired in proper sequence~ however, only in
response to forward rotation of the engine~ If the enyine
rotation is reversed the reatifiers will be fired:180 out of
phase and thus prevent the engine from running backwards.
Referring particularly to Figs. 2, 4 and 5, the power
generating section 21 generally includes the rotor section
secured to the inner portion of skirt 29 of the flywheel 16 and
includes a plurality of permanent magnets which are opposltely
and radially polarized to define first polarity magnets 63 and
second opposite polarity magnets 64. The oppositely polarized
magnets 63 and 64 also define flux reversal points or areas be-
tween the adjacent magnets 63 and 64, and thus at the junctions
or adjacent ends 65 and 66, The illustrated permanent magnets 63
and 64 are polarized radial].y of the rotor, as shown by polarity
dots.
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In addition, the generatin~ section 21 includes the
stator section 31 attached to the support hub 41 and secured in
fixed relation to the engine block 17 and the core 40 of the
ignition section 20. The section 21 includes a plurality of
angularly spaced power coils, shown as flve coils 32. The
coils 32 are connected in series aiding, as shown in Fig. 5,
to produce an alternating current output of relatively high power
level at leads 6 to rectifier 7, for example, 50 watts of
rectified power from the rectifier 7. A stator core 31 is
provided having five pole members 67 on which the coils 32 are
wound. The stator core 31 is a laminated unit having the pole
members 67, spaced in accordance with the spacing of five
adjacent magnets 63 and 64. Core 31 is suitably attached to the
hub ~l to the opposite side of the shaft opening from the
stator core 40. Core 31 is mounted on a raised platform 68
of the hub 41 and thus offset from the plane of the ignition
stator core 40, with the stator core 31 and coil~ 32 in the plane
of the power permanent magnets ~3 and 6~ in the assembled unit.
The coil~ 32 are thus sequentially aligned with the magnets
63 and 6~ and an alternatiny half cycle signal is generated
each time an air gap 65~66 passes a coil 32. As the magnets
63 and 64 are oppositely polarized, the adjacent coils 32 are
also oppositely wound and connected such tha-t the output of the
coils are added to give a total voltage and current. Successive
half cycles generated in each coil 32 are of opposite polarity as
the rotor rotates to generate a generally sinusoidal alternating
current outputO The alternating current output is rectified by
the rectifier 7 to produce a suitable D.C. power for charging
a battery or the alternating output may be D.C. regulated to power
running lights. The field of the power magnet 30 includes leakage
into the plane of ignition section 20 and includes a corresponding
voltage and current in the charging coils 22 and in the timing
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coil 23. The ripple or induced Yoltaye in the char~iny coils Z2
does not affect the pxoper char~ing of khe capacitor 10 and 11
to the proper voltage level. ~owever, a superimposed voltage
on the trigger coil 23 may affect the timing and firing o the
engine by changing the trigger pulse position relative to the
crankshaft position. The inventor has fo~md however that the
power and ignition sections 2Q and 21 may be mounted with
leakage cross-magnetization by constructing the power section
21 to induce a symmetrical leakage or ripple signal on the
desired trigger signal, as shown in Fig. 6. Thus, any charges
resulting from the leakage signal similarly affects and changes
every trigger signal. This will then maintain good symmetry in
the affect on the timing of the two cylinders and permit the
proper setting of the position of trigger coil 23 to main-tain
proper and efficient engine operation. The power magnet 30 thus
includes an odd multiple of the number of magnets in ignition
magnet 33. In the illustrated embodiment, magnet unit 30
includes fourteen poles 63 - 64, as shown in Fig. 5, ~ormed in
the magnetic strip and thus a multiple o~ seven of the two
magnets o~ the ignition section 20. The even number of poles or
flux reversals of the magnet 30 induces a ripple voltage in the
ignition section 20 which similarly affects each trigger signal
and may therefore, be coupled to the ignition section without
adYerse affect on the ignition and particularly the timing.
This permits construction of a compact alternator with the dual
generating sections in close proximity within the cup shaped
~lywheel.
The present invention thus provides a small, compact
dual alternator construction for powering an ignition system and
a power load and which can be economically pxoduced. The
alternator construction is uniquely adapted for use in structures
having relatively sev~re space limitations such as low horsepower
outboard motors and the l:ike.
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Various modes of carrying out the invention are
contemplated as being within the scope of the following
claims, particularly pointing out and distinctly claiming
the subject matter which is regarded as the invention.
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