U.S. patent number 3,788,293 [Application Number 05/305,308] was granted by the patent office on 1974-01-29 for low impedance capacitor discharge system and method.
This patent grant is currently assigned to McCulloch Corporation. Invention is credited to Harold E. Anderson.
United States Patent |
3,788,293 |
Anderson |
January 29, 1974 |
LOW IMPEDANCE CAPACITOR DISCHARGE SYSTEM AND METHOD
Abstract
A low impedance capacitor discharge ignition system and method
in which a supplemental capacitor is utilized on the secondary
winding side of the high voltage transformer to avoid the impedance
of the transformer in sustaining the gap ionization potential of
the ignition device.
Inventors: |
Anderson; Harold E. (Los
Angeles, CA) |
Assignee: |
McCulloch Corporation (Los
Angeles, CA)
|
Family
ID: |
23180271 |
Appl.
No.: |
05/305,308 |
Filed: |
November 10, 1972 |
Current U.S.
Class: |
123/620;
123/654 |
Current CPC
Class: |
F02P
9/007 (20130101) |
Current International
Class: |
F02P
9/00 (20060101); F02p 001/00 () |
Field of
Search: |
;123/148E,148DC,148AC |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Assistant Examiner: Cox; Ronald B.
Attorney, Agent or Firm: Burns, Doane, Swecker &
Mathis
Claims
What is claimed is:
1. A method of sustaining the duration of the gap ionization
potential applied to an ignition device in a capacitor ignition
system comprising the steps of:
a. alternately charging a primary capacitor from a first current
source and discharging the primary capacitor through a high voltage
transformer and an ignition device to initiate the application of a
gap ionization potential to the ignition device; and,
b. alternately charging a supplemental capacitor from a second
current source and discharging the supplemental capacitor through
the ignition device but not through the high voltage transformer in
timed relation to the charging and discharging of the primary
capacitor, whereby the impedance of the high voltage transformer is
avoided in discharging the supplemental capacitor through the
ignition device and sustaining the duration of the gap ionization
potential thereof.
2. The method of claim 1 wherein the discharge of the supplemental
capacitor is initiated before the discharge of the primary
capacitor is terminated.
3. The method of claim 2 wherein the primary and secondary
capacitors are charged from different sources.
4. The method of claim 3 wherein the peak amplitude of the gap
ionization potential applied to the ignition device from the
supplemental capacitor is greater than about fifteen percent of the
peak amplitude of the gap ionization potential applied to the
ignition device from the primary capacitor.
5. The method of claim 4 wherein the duration of the discharge of
the primary and supplemental capacitors is substantially equal.
6. The method of claim 1 wherein the peak amplitude of the gap
ionization potential applied to the ignition device from the
supplemental capacitor is greater than about twenty-five percent of
the peak amplitude of the gap ionization potential applied to the
ignition device from the primary capacitor.
7. The method of claim 6 wherein the discharge of the supplemental
capacitor is initiated before the discharge of the primary
capacitor is terminated.
8. A low impedance capacitor discharge ignition system
comprising:
a primary capacitor;
a first source of direct current;
a high voltage transformer;
first switch means operable to connect said primary capacitor to
said first source of direct current to charge said primary
capacitor therefrom and to connect said primary capacitor to said
high voltage transformer to discharge said primary capacitor
through the primary winding thereof;
a supplemental capacitor;
a second source of direct current;
an ignition device connected in series with the secondary winding
of said transformer to receive a gap ionizing potential upon the
discharge of said primary capacitor; and,
circuit means operable to connect said supplemental capacitor to
said second source of direct current to charge said supplemental
capacitor therefrom and to connect said supplemental capacitor to
said ignition device to discharge said supplemental capacitor
through said ignition device in timed relation to the discharge of
said primary capacitor.
9. The system of claim 8 wherein said switch means include
mechanically actuable breaker points.
10. The system of claim 8 wherein said switch means include coils
and a permanent magnet movable with respect to each other.
11. The system of claim 8 wherein first switch means and said
circuit means are operable to initiate the discharge of said
primary and supplemental capacitors at substantially the same
time.
12. The system of claim 11 wherein the duration of the discharge of
said primary and supplemental capacitors is substantially
equal.
13. The system of claim 8 wherein the duration of the discharge of
said primary and supplemental capacitors is substantially
equal.
14. A method of reducing the emission of hydrocarbons from an
internal combustion engine having an ignition device by increasing
the power applied to the ignition device comprising the steps
of:
a. discharging a first capacitor through a high voltage transformer
to apply a gap ionization potential to the ignition device;
and,
b. discharging a second capacitor to apply a gap ionization
sustaining potential to the ignition device through a circuit
excluding the impedance of the high voltage transformer whereby the
power applied to the ignition device may be increased.
15. The method of claim 14 wherein the discharge of the primary and
supplemental capacitors is substantially simultaneous.
16. The method of claim 15 wherein the gap ionization potential
applied by the primary capacitor to the ignition device is
substantially in excess of the gap ionization sustaining potential
applied by the supplemental capacitor to the ignition device.
17. The method of claim 14 wherein the gap ionization potential
applied by the primary capacitor to the ignition device is
substantially in excess of the gap ionization sustaining potential
applied by the supplemetal capacitor to the ignition device.
18. A low impedance capacitor discharge system comprising:
an ignition device;
a high voltage transformer;
means for applying a gap ionizing potential to said ignition device
through a circuit including said high voltage transformer; and,
means for applying a gap ionization sustaining potential to said
ignition device through a circuit excluding said high voltage
transformer whereby the impedance to the application of power to
said ignition device may be reduced.
19. The system of claim 18 wherein the gap ionizing potential and
the gap ionization sustaining potential are substantially
coextensive.
20. The system of claim 19 wherein the average gap ionizing
potential is significantly greater than the average gap ionization
sustaining potential.
21. The system of claim 18 wherein said means for applying a gap
ionizing potential and for applying a gap ionization sustaining
potential to said ignition device comprises:
first and second capacitors;
movable magnetic means
a coil disposed in flux cutting proximity to the path in which said
magnetic means moves;
unidirectional current means for connecting said coil to said first
and second capacitors;
first switch means operable in synchronism with movement of said
magnetic means for connecting said first capacitors to said
discharge device through said transformer; and,
second unidirectional current means for connecting said second
capacitor to said discharge device in synchronism with the
discharge of said first capacitor.
22. The system of claim 18 wherein said means for applying a gap
ionizing potential to said ignition device includes a first
capacitor, movable magnetic means, a coil disposed in flux cutting
proximity to the path in which said magnetic means moves, and first
switch means operable in synchronism with movement of said magnetic
means for connecting said first capacitor to said ignition device
through said transformer; and,
wherein said means for applying a gap ionization sustaining
potential to said ignition device includes a second capacitor, a
source of direct current, and diode means for connecting said
second capacitor to said ignition device in synchronism with the
discharge of said first capacitor.
Description
BACKGROUND OF THE INVENTION
Capacitor discharge ignition systems in common use generally employ
a discharge capacitor which is alternatively connected between a
source of direct current and the primary winding of a high voltage
transformer having its secondary winding connected to the ignition
device. The capacitor in such systems may receive direct current
from a storage device or from a coil disposed in flux cutting
proximity to a magnetic element movable in response to rotation of
the engine. The switch means customarily employed to alternatively
connect the capacitor to the source of direct current and to the
primary winding of the high voltage transformer may be of the solid
state type, e.g., a silicon controlled rectifier, and operable in
response to engine rotation by means of a trigger coil disposed in
flux cutting proximity to the same magnetic element as the current
source. Alternatively, the switch may be breaker points
mechanically operable in response to engine rotation in a
conventional manner.
Capacitor discharge ignition systems of the type above described
suffer from the disadvantage that the charge in the capacitor is
applied to the ignition device through the high voltage
transformer. While the impedance of the high voltage transformer is
generally quite small upon the initial application of the discharge
pulse, the impedance of the high voltage transformer becomes quite
large as the passage of current through the windings of the
transformer is sustained. The impedance of the high voltage
transformer thus significantly reduces the potential applied to the
ignition device.
The reduction in the potential applied to the ignition device due
to the high voltage transformer impedance is not nearly so
significant at very high engine speeds or under the circumstances
where atomized fuel is in immediate proximity to the electrode of
the ignition device at the time that the arc is initiated. However,
and as is well known, the likelihood that sufficient atomized fuel
will be in such proximity is significantly reduced at low engine
speeds and as a result, the potential applied to the ignition
device may be insufficient to ignite the fuel when the fuel does
become present. Even where the fuel does ignite late in the cycle,
the efficiency of the fuel combustion is severely reduced. This
reduction in efficiency adds significantly to the unburned
hydrocarbons and thus the pollution problem plaguing many parts of
the country.
In addition, the increased potential permits the combustion of
leaner mixtures and the present invention has been successfully
utilized with air/fuel ratios of about 30 to 1. This excessive air
serves to cool the combustion below the knee in the
emission/temperature curve, i.e., about 3,200.degree. F, as a
result of which the presence of unburned hydrocarbons is
significantly reduced.
It is accordingly an object of the present invention to obviate
many of the problems associated with generally known capacitor
discharge ignition devices and to provide a novel method and system
for sustaining the gap ionization potential of an ignition device
in a capacitor discharge ignition system.
It is another object of the present invention to provide a novel
method and system for combating pollution by increasing the
efficiency of fuel combustion in internal combustion engines.
It is still another object of the present invention to provide a
novel method and system for supplementing the gap ionization
potential applied to the ignition device of an internal combustion
engine in which the impedance of the high voltage transformer may
be avoided.
These and many other objects and advantages of the present
invention will be readily apparent to one skilled in the art to
which the invention pertains from the claims and from a perusal of
the following detailed description when read in conjunction with
the appended drawings.
THE DRAWINGS
FIG. 1 is a schematic circuit diagram of one embodiment of the
present invention;
FIG. 2 is a graph of the potential applied to the ignition device
with respect to time; and,
FIG. 3 is a schematic circuit diagram of the second embodiment of
the present invention.
THE DETAILED DESCRIPTION
With reference now to FIG. 1, a source of direct current (not
shown) may be applied to the input terminals 10 and 12 and the
input terminal 10 connected through a diode 14 to one terminal 16
of a single pole, double throw switch schematically illustrated.
The other terminal 18 of the switch is connected to one end of the
primary winding 20 of a high voltage transformer and the other end
thereof is connected to the terminal 12. The switch arm 22 is
operable to connect the primary capacitor 24 across the input
terminals 10 and 12.
One end of the secondary winding 26 of the high voltage transformer
is grounded and the other end thereof may be connected through a
diode 28 to the ignition device 30. The ignition device 30 may be
paralleled by a supplemental capacitor 32 connected through diodes
36 and 38 to a terminal 40 intermediate the diode 28 and the
ignition device 30. The supplemental capacitor 32 may in turn be
paralleled by a suitable conventional source of direct current such
as a battery 42 and a diode 44.
In operation with the switch arm 22 in contact with the terminal
16, the direct current applied to the input terminal 10 may be
applied through the diode 14 to the capacitor 24 to charge the
capacitor 24. Once the capacitor 24 has been charged, the movement
of the switch arm 22 to the terminal 18 provides a discharge path
for the capacitor 24 through the primary winding 20 of the high
voltage transformer. The current pulse thus generated in the
secondary winding 26 of the high voltage transformer is supplied
through the diode 28 to the ignition device 30 and is of sufficient
magnitude to ionize the gap thereof.
The operation of the circuit thus far described is conventional. In
such circuits, the diode 14 may be eliminated by the use of the
switch as described or alternatively the capacitor 24 may be
directly connected to the terminal 16 and the switch disposed
between the illustrated terminal 18 and the primary winding 20 of
the high voltage transformer. In a typical embodiment having values
hereinafter set forth, the potential applied to the ignition device
by the circuit of FIG. 1 thus operated may take the shape of the
waveform illustrated in dashed lines in FIG. 2. With reference to
FIG. 2, the waveform includes a brief initial portion having an
amplitude approximately one order of magnitude higher than the
amplitude of the remainder of the waveform due to the impedance of
the high voltage transformer.
With continued reference to FIG. 1, the supplemental capacitor 32
may be charged from the battery 42 through the diode 44. Once
charged, the supplemental capacitor 32 may be discharged through
the diodes 36 and 38 and the ignition device 30. The charge on the
supplemental capacitor 32 may thus be dissipated through the
ignition device 30 while avoiding the impedance of the high voltage
transformer.
It is necessary that the discharge of the primary capacitor 24 and
the supplemental capacitor 32 be synchronized so that the discharge
impulses are supreimposed on the ignition device 30. The operation
of the switch 22 may be controlled in any suitable conventional
manner in timed relationship to engine rotation. The simultaneous
discharge of the capacitor 32 has been found for the circuit values
hereinafter set forth to provide a threefold increase in the
amplitude of the ignition device potential as shown in FIG. 2.
Simultaneous discharge of the capacitors 24 and 32 is assured by
the impedance of the ignition device 30 which acts as an open
circuit during the charging of the capacitor 32 from the battery
42. Once the ignition device has received an ionizing potential,
the impedance of the spark gap drops sufficiently to provide a
discharge path for the capacitor 32 through the diodes 36 and 38.
The voltage drop across the diodes 36 and 38 is, moreover,
sufficient to insure the effective disconnecting of the capacitor
32 from the ignition device 30 once the capacitor 32 has been
discharged.
With continued reference to FIG. 1, the diodes 28, 36 and 38 may
have a 10 Kv. 2.5 amp rating for use with a 3 Kv. 100 watt source
42 and a 1 microfarad capacitor 32. By means of the discharge of
the supplemental capacitor, the normal 0.321 Kv. ionization
sustaining potential applied to the ignition device 30 may be
increased to approximately 3 Kv.
With reference now to FIG. 3, a flywheel 50 is schematically
illustrated having a permanent magnet 52 and pole pieces 54 and 56
for rotation in response to engine rotation. A current coil 58 may
be disposed in flux cutting proximity to the flywheel 50 and may be
connected across a primary capacitor 60 by way of a diode 62. The
diode 62-capacitor 60 interconnection may be connected through a
switch 68 to the primary winding 70 of a high voltage transformer
to provide a discharge path for the capacitor 60 through the
primary winding 70. The secondary winding 72 of the high voltage
transformer may be connected through a diode 74 across the ignition
device.
The switch 68 may be any suitable conventional switch and may, for
example, be a silicon controlled rectifier having a gate electrode
connected to a trigger coil 82 also disposed in flux cutting
relationship to the flywheel 50. The switch 68 may alternatively be
a mechanical switch operable by a trigger coil 82 or any suitable
conventional cam mechanism to provide the desired synchronization
with engine rotation.
With continued reference to FIG. 3, the current coil 58 may also be
connected through a full wave rectifier 82 to the alternator 84 of
the vehicle to provide a 12v. a.c. signal to a transformer 86 where
the signal is increased to about 1 Kv. a.c. This high voltage
signal may be applied through a full wave rectifier 88 to the
supplemental capacitor 64 to effect the charging thereof. As
earlier explained in connection with the circuit of FIG. 1, the
ionization of the spark gap of the ignition device 76 provides a
discharge path for the capacitor 64 through a diode 80 and the
ignition device 30.
In operation, the rotation of the flywheel 50 and the magnetic
elements contained therein past the stationary current coil 58 will
generate a current pulse therein and this current pulse will be
applied through the diode 62 to charge the primary capacitor 60.
Operation of the switch 68 will provide, by the ionization of the
spark gap, a discharge path for the supplemental capacitor 64
through the diode 80 to the ignition device 76. As is readily
apparent, this latter discharge path does not include the impedance
of the high voltage transformer and the gap ionization sustaining
potential may be appreciably increased.
While only one discharge device has been illustrated and described,
it is to be understood that the present invention contemplates the
utilization of rotor and multiple ignition devices such as commonly
found in multiple cylinder internal combustion engines.
ADVANTAGES AND SCOPE OF THE INVENTION
As is readily apparent from the foregoing description, the novel
method and system of the present invention significantly increases
the ignition device gap ionization sustaining potential by means of
a supplemental capacitor and a discharge path therefore excluding
the impedance of the high voltage transformer through which the gap
ionization potential is initially applied. By means of the present
invention, the efficiency of an internal combustion engine may be
significantly increased, particularly at low engine speeds, and the
emission of unburned hydrocarbons significantly reduced. By
avoiding the impedance of the high voltage transformer for the gap
ionization sustaining potential, the size of the primary capacitor
may be significantly reduced for any predetermined gap ionization
sustaining potential.
The present invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The presently disclosed embodiments are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the invention being indicated by the appended claims
rather than by the foregoing description, and all changes which
come within the meaning and range of equivalency of the claims are
therefore intended to be embraced therein.
* * * * *