U.S. patent number RE31,837 [Application Number 06/051,983] was granted by the patent office on 1985-02-26 for single core condenser discharge ignition system.
This patent grant is currently assigned to R. E. Phelon Company, Inc.. Invention is credited to Bob O. Burson.
United States Patent |
RE31,837 |
Burson |
February 26, 1985 |
Single core condenser discharge ignition system
Abstract
A breakerless condenser discharge ignition system for an
internal combustion engine and excited by a rotating permanent
magnet, consists of a single module, containing a number of
windings and electrical components, mounted on one pole of a
ferromagnetic core for producing high voltage output pulses for
firing an associated spark plug.
Inventors: |
Burson; Bob O. (East
Longmeadow, MA) |
Assignee: |
R. E. Phelon Company, Inc.
(East Longmeadow, MA)
|
Family
ID: |
26730031 |
Appl.
No.: |
06/051,983 |
Filed: |
June 25, 1979 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
572908 |
Apr 29, 1975 |
04036201 |
Jul 19, 1977 |
|
|
Current U.S.
Class: |
123/601;
123/599 |
Current CPC
Class: |
F02P
11/025 (20130101); F02P 1/086 (20130101) |
Current International
Class: |
F02P
1/08 (20060101); F02P 1/00 (20060101); F02P
11/00 (20060101); F02P 11/02 (20060101); F02P
003/06 (); F02P 003/08 () |
Field of
Search: |
;123/149R,149C,149D,148E,148CC,599-602 ;315/218,29SC,29CD
;310/7R,153,156 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Argenbright; Tony M.
Attorney, Agent or Firm: Chapin, Neal & Dempsey
Claims
I claim:
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 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 said primary winding
and charging winding opposite to the ends of these windings
interconnected by the cathode-anode 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 as defined in claim 3 further
characterized by a thin walled cup-shaped housing received on said
one portion of said core of ferromagnetic material and containing
said primary winding, said secondary winding, said charging
winding, said capacitor, and said electronic switch, and an
insulated high tension conductor for connecting one end of said
secondary winding to said spark plug, said housing also having a
socket for receiving one end of said high tension conductor and
means in said socket for making electrical connection between said
one end of said conductor and one end of said secondary winding.
.Iadd.
6. In a capacitor discharge system for an internal combustion
engine having permanent magnet means rotatable about a circular
path in synchronism with the operation of said engine, a charge
coil, a capacitor connected in circuit with said charge coil and an
electronic switch means which is rendered conductive in response to
a trigger pulse connected to said switch means for discharging said
capacitor into the primary winding of a transformer ignition coil,
the secondary winding of said transformer being connected to a
spark gap device for said engine, the improvement in said system
comprising an integral core of ferromagnetic material which
includes a plurality of circumferentially spaced, radially
extending leg portions disposed adjacent said circular path, one of
said leg portions providing a path for varying flux generated by
the movement thereby of said magnet means, said charge coil being
connected to charge said capacitor and together with said
transformer coil being disposed on said one leg portion, said
charge coil and transformer coil being offset radially with respect
to the circular path of said magnet means, said coils being wound
such that voltages simultaneously induced therein by said varying
flux in said one leg portion include half wave voltages of opposite
polarity, said capacitor being charged by voltage of one polarity
generated in said charge winding and said electronic switch means
being rendered conductive by a trigger voltage the same as said one
polarity which occurs during generation in the charge winding of a
voltage opposite said one polarity which charges said capacitor
whereby said capacitor is charged during one half cycle of voltage
induced in the charging coil by changing flux in said one leg
portion and discharged during the next half cycle of voltage
induced in one of said coils by said changing flux in said one leg
portion. .Iaddend. .Iadd.7. In a capacitor discharge ignition
system as set forth in claim 6 wherein said charge coil is offset
from said transformer coil in the direction of said rotating magnet
means. .Iaddend. .Iadd.8. In a capacitor discharge ignition system
as set forth in claim 6 wherein said core has three radially
extending leg portions with said charge coil and said transformer
coil disposed on the center leg portion of said core. .Iaddend.
.Iadd.9. In a capacitor discharge system for internal combustion
engines as set forth in claim 6 wherein said charge coil and
transformer coils are essentially the only voltage generating coils
employed in said system whereby capacitor charging, the electronic
switch means triggering and the transformer ignition functions are
all performed by said charging coil and transformer coil in the
absence of a separate trigger coil. .Iaddend. .Iadd.10. In a
capacitor discharge ignition system as set forth in claim 7 wherein
said transformer coil includes a primary winding and secondary
winding disposed in generally concentric relation on said one leg
portion, said charge coil being offset a substantial distance from
the secondary winding of the transformer coil. .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to condenser discharge ignition systems for
use with spark ignited internal combustion engines, and deals more
particularly with improvements in such systems which are excited by
a permanent magnet means orbiting in synchronism with the operation
of the associated engine.
The ignition system of this invention is particularly useful in
association with small single cylinder internal combustion engines
of the type commonly used for powering lawn mowers, chain saws,
snow blowers and the like. It is therefore shown herein as a unit
adapted for use with such single cylinder engines. It should,
however, be understood that the invention is not necessarily
limited to such application and that it may also be used with
multicylinder engines either by providing a distributor between the
high tension terminal of the illustrated stator unit and the spark
plugs or by providing a plurality of stator units matching the
number of plugs.
The small engine market is a relatively competitive one and,
therefore, one of the basic purposes of this invention is to
provide a relatively low cost and yet reliable ignition system for
use with small single cylinder engines. In keeping with this
purpose a further object of the invention is to provide a condenser
discharge ignition system having a stator unit consisting of a
reduced number of parts in comparison with generally similar
systems presently available so as to reduce the cost of making the
stator unit and to reduce the amount of time and effort required
for its assembly with the engine.
Another object of the invention is to provide an ignition system of
the foregoing character in which the stator unit is of a relatively
small and compact size and requires a minimum number of mechanical
and electrical connections for its assembly with the remainder of
the engine. In particular, the ignition system of this invention,
apart from the rotating magnet, may be made as a single physical
stator unit easily mechanically mounted to the stationary structure
of an engine and requiring only two electrical connections, one of
these electrical connections being a ground connection to the
engine structure and the other being a high tension connection from
the unit to the associated spark plug. An additional circuit
consisting merely of a normally open manually operable switch
connected between the unit and ground may also be optionally
provided for use in stopping the engine.
Other objects and advantages of the invention will be apparent from
the following descriptions and from the drawings forming a part
hereof.
SUMMARY OF THE INVENTION
This invention resides in a capacitor discharge ignition system for
supplying high voltage power at proper times to the spark plug or
plugs of a spark ignited internal combustion engine. The system
includes a permanent magnet means which is rotated, as by a
flywheel, about a circular path in synchronism with the operation
of the associated engine. A core of ferromagnetic material is
mounted adjacent the path of the magnet and has one pole or other
portion through which a changing amount of flux from the magnet
passes each time the magnet moves past the core. All of the
windings of the ignition system are wound on the one core portion,
these windings being three in number and comprising a primary
winding and a secondary winding of a transformer and a charging
winding. Since the charging winding and the primary winding are on
the same core portion, simultaneous voltage waveforms, each
consisting of two half cycles of opposite polarity, are induced in
each winding by the changing amount of flux each time the magnet
moves past the core. A capacitor is connected by a charging circuit
across the charging winding with the charging circuit including a
diode poled so that the capacitor is charged during the first half
cycle of the voltage waveform induced in the charging winding. A
discharging circuit connects the primary winding across the
capacitor and includes a silicon controlled rectifier or other
normaly nonconducting electronic switch which prevents discharge of
the capacitor through the primary winding until the electronic
switch is switched to its conducting state. A trigger circuit
couples the primary winding with the control or trigger terminal of
the electronic switch so that a control or trigger signal is
applied to the electronic switch to switch it to its conducting
state during the second half cycle of the voltage induced in the
primary winding. Preferably, the primary and secondary windings are
arranged with one surrounding the other, and the charging winding
is spaced from the primary and secondary windings so that during
discharge of the capacitor through the primary winding a major
amount of the flux linking the primary and secondary windings does
not link the charging winding.
The invention also resides in all of the windings and electrical
components of the ignition system except for the magnet and spark
plug, being contained in a single housing and making up a module
mounted on a core of ferromagnetic material so as to form a unit
requiring only two external electrical connections, one to ground
and one to the spark plug, for operation of the system.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view partly in elevation and partly in section, taken
on the line 1--1 of FIG. 2, of a capacitor discharge ignition
system embodying this invention.
FIG. 2 is a vertical sectional View taken on the line 2--2 of FIG.
1.
FIG. 3 is an enlarged sectional view taken on the line 3--3 of FIG.
2, through the core and module assembly of the ignition system of
FIG. 1.
FIG. 4 is a top view of the core and module assembly of FIG. 3 with
the potting material being shown removed from the module
housing.
FIG. 5 is an enlarged fragmentary sectional view taken on the line
5--5 of FIG. 4.
FIG. 6 is an exploded view of the core and module assembly of FIG.
3.
FIG. 7 is a schematic wiring diagram of the ignition system of FIG.
1.
FIG. 8 is a graph illustrating voltage waveforms appearing across
various parts of the ignition system of FIG. 1 during one passage
of the magnet past the core.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning to the drawings, and first considering FIGS. 1 and 2, these
figures show a stator unit 10 and a permanent magnet assembly 12
comprising, except for an associated spark plug, substantially all
of a breakerless condenser discharge ignition system for a single
cylinder internal combustion engine.
The permanent magnet assembly 12 is or may be of generally
conventional construction consisting of a permanent magnet 14 and
two pole pieces 16 and 18. The magnet assembly 12 is molded into
the rim 20 of a nonmagnetic flywheel 22 fixed to a shaft 24 of an
engine 26 for rotation with the shaft about a circular path. The
shaft 24 is a shaft, such as the crankshaft or camshaft, which
rotates is synchronism with the operation of the engine so that
movement of the magnet assembly 12 past any given point in its
circular path is timed in relation to the operating cycle of the
engine. In addition to the rim 20, the flywheel 22 includes a hub
28 and a radially extending web 30 between the hub and the rim, the
hub, web and rim defining an annular cavity which receives the
stator unit 10.
The stator unit 10 includes a base member 32 of non-magnetic
material, having an opening through which the hub 28 and shaft 24
pass, supported from the stationary structure on the engine 26 by
three studs 34, 34. The base in turn carries a coil and module
assembly consisting of a ferromagnetic core 36 and a winding and
component module 38.
FIGS. 3 and 6 show in detail the construction of the core 36 and
the winding and component module 38. Referring to these figures,
the core 36 is a ferromagnetic flux conducting member, made of
laminated iron, having at least one portion in which a changing
magnetic flux is created as the magnet assembly moves past the
core, and the module 38 is located on the core so as to surround
such portion. In particular, the core 36 is one having three poles
40, 42 and 44 spaced from one another along the circular path of
the magnet assembly 12. From FIG. 1, it will be understood that as
the magnet assembly 12 moves past the core 36, the flux in the
middle pole 42 is first in one direction, as the pole piece 18
passes thereover, and is then in the other diection, as the pole
piece 16 passes thereover.
The module 38 is mounted on the middle core pole 42. It includes a
thin walled cup-shaped housing 46 made of a plastic material and
containing three electrical windings. These windings are a
transformer primary winding 48, a transformer secondary winding 50
and a charging winding 52. The primary winding 48 and charging
winding 52 are wound on a plastic bobbin 54 initially separate from
the housing 46. The bobbin has two radially extending flanges 56,
56 between which the charging winding 52 is located and two other
radially extending flanges 58, 58 between which the primary winding
48 is located.
The module housing 46 includes an axially extending chimney portion
60 within which that portion of the bobbin 54 containing the
primary winding 48 is contained. The secondary winding 50 surrounds
the chimney 60 so as to also surround the primary winding 48. The
bobbin 54 has a central opening extending completely therethrough
and of a square cross section conforming to the square cross
section of the pole 42. As shown in FIGS. 3 and 4, the housing 46
includes an intermediate wall 62, to the left of the secondary
winding 50, forming a pocket 64 for receiving a condenser 66, a
silicon controlled rectifier 68 and other electrical components
shown hereinafter in the schematic diagram of FIG. 7.
The components contained in the pocket 64, the primary winding 48,
the secondary winding 50 and the charging winding 52 are
electrically connected with one another, as in the wiring diagram
of FIG. 7, by suitable leads contained within the housing 46. Also,
the three windings, the components in the pocket 64, the bobbin 54
and the housing 46 are all mechanically fixed relative to one
another by a potting material 70 filling the otherwise empty space
of the housing. The module 38 is suitably mechanically fixed to the
pole 42 as by an adhesive between the interior surface of the
bobbin 54 and the pole 42.
As shown best in FIGS. 4 and 5, the module housing 46 also includes
a portion 72 defining a socket 74 for receiving the end portion of
an insulated high tension conductor 76 for connecting the module to
an associated spark plug. At the inner end of the socket 74 is a
tack 78 connected to the high tension end 80 of the secondary
winding 50 for making electrical contact with the end of the
conductor 76 received in the socket 74.
Referring to FIG. 7, the charging winding 52 is connected across
the capacitor 66 by a charging circuit including a diode 82. The
capacitor 66 is also connected across the primary winding 48 by a
discharging circuit including the silicon controlled rectifier
(SCR) 68. The SCR 68 is normally nonconducting and acts as an
electronic switch for preventing discharge of the capacitor 66
through the primary winding 48 until it is triggered or switched to
a conducting state.
The triggering circuit for the SCR 68 is coupled with the primary
winding 48 so that the voltage induced in the primary winding 48,
as the magnet assembly moves past the core 36, is utilized to
provide a trigger signal for the SCR, thereby eliminating the need
for a separate additional trigger winding. This trigger circuit in
turn consists merely of a resistor 84 connected between one end of
the primary winding 48 and the gate or control terminal 86 of the
SCR 68.
Still referring to FIG. 7, the charging winding 52 and the primary
winding 48 are wound and so located on the pole 42 so that the ends
thereof marked by the dots are of common polarity. Also, one end of
the coil 48, one end of the resistor 84, one end of the capacitor
66, one end of the charging winding 52 and one end of the secondary
winding 50 are all connected to ground by the line 88. The
ungrounded or high tension end of the secondary winding 50 is
connected to the high tension terminal of the associated spark plug
90 by the line 76. Additionally, the system of FIG. 7 may include
an additional circuit consisting of a line 92 connected to ground
through a normally open manually operable switch 94. The switch 94
is useful in stopping the operation of the engine since when the
switch 94 is closed it shorts out the charging winding 52 to
prevent charging of the capacitor 66 and consequent firing of the
plug 90.
In considering the operation of the system of FIG. 7, reference may
be had to FIG. 8 which shows the waveforms of the voltages
appearing across the charging winding 52, across the primary
winding 48 and across the condenser 66 during one passage of the
magnet assembly 12 past the core 36. In FIG. 8, E.sub.g is the
voltage as seen by diode 82 induced in the charging winding 52 by
the magnet assembly and E.sub.p is the voltage induced in the
primary winding 48 by the magnet assembly as seen by gate 86 of the
SCR. E.sub.c is the voltage across the capacitor. Each of the
waveforms E.sub.g and E.sub.p occur simultaneously and each
includes two half cycles of opposite polarity. The diode 82 is so
poled that during the first half cycle of the voltage waveform
E.sub.g induced in the charging winding 52 the capacitor 66 is
charged. The charge on the capacitor is held into the next half
cycle of the voltage waveform E.sub.g until the voltage E.sub.p
rises, in the second half cycle thereof, to a level sufficient to
cause triggering of the SCR 68. In FIG. 8, the line 96 represents
the triggering level which the voltage E.sub.p needs rise to to
cause triggering of the SCR 68. When the voltage E.sub.p does reach
the triggering level, the SCR is triggered to its conducting state
and the condenser 66 is discharged through the primary winding 48
to induce a high output voltage across the secondary winding 50
which fires the associated spark plug 90.
When the capacitor 66 is discharged to cause firing of the spark
plug 90 the capacitor discharge current flowing through the primary
winding 48 sets up a changing magnetic flux in the pole 42,
indicated by the broken lines 98, 98 of FIG. 3 which link the
primary and secondary windings. It is desirable that this flux not
link the charging winding 52 since, if it does, the charging
winding 52 will act as a shorting coil and impair the generation of
the high voltage output in the secondary winding 50. Therefore, as
shown in FIG. 3, the charging winding 52 is preferably spaced a
substantial distance along the length of the pole 42 from the
primary winding 48 and secondary winding 50 so that a major portion
of the flux which does link the primary and secondary windings
during capacitor discharge will not link the charging winding
52.
It will also be noted from FIG. 1 and FIG. 7 that, apart from the
stop switch circuit which is optional, the only electrical
connections required for the module 38 are the ground connection
made by the line 88 and the high tension connection to the spark
plug made by the conductor 76. The grounding of the line 88 may be
accomplished in various different ways, and in FIG. 1 is shown to
be accomplished by connecting the free end of the line 88 to the
base 32 by a screw 100, the base 32 being made of an electrically
conductive material and being electrically connected to the engine
26 through the studs 34, 34.
* * * * *