 |
Description  |
|
|
This invention is directed to an internal combustion engine ignition system
and, more specifically, to a dual action internal combustion engine
ignition system which produces a high ignition arc-creating potential in
the secondary winding of the ignition coil in response to the simultaneous
interruption of the energizing circuit of one or more of the ignition coil
primary windings and the discharge of a capacitor through one or more
other ignition coil primary windings.
In the inductive discharge type ignition systems for internal combustion
engines, the primary winding of an ignition coil is connected to a source
of potential through a current interrupting device which is operated in
synchronism with the engine to complete and then, each time a spark plug
is to be fired, to abruptly interrupt the ignition coil primary winding
energizing current. The resulting induced high ignition arc-creating
potential in the secondary winding is applied, usually through an ignition
distributor, to the spark plugs of the engine in sequence so as to create
successive fuel igniting ignition arcs across the arc gaps of the
respective spark plugs. Because of certain ignition coil design
limitations well known in the art, the prior art inductive type internal
combustion engine ignition systems may not create a high ignition
arc-creating potential in the secondary winding of a sufficiently short
rise time to fire fouled spark plugs or to ignite non-homogeneous or lean
fuel-air mixtures, a condition which results in engine misfire. The
provision of a dual action internal combustion engine ignition system
which provides a high ignition arc-creating potential of a sufficiently
fast rise time to insure that fouled spark plugs are fired and to insure
that non-homogeneous or lean fuel-air mixtures be ignited and which
provides an ignition arc of sufficient duration to insure effective
fuel-air mixture combustion is desirable.
It is, therefore, an object of this invention to provide an improved
internal combustion engine ignition system.
It is an additional object of this invention to provide an improved
internal combustion engine ignition system of the dual action type which
provides a high ignition arc-creating potential in response to the
simultaneous action of an inductive discharge ignition system and a
capacitor discharge ignition system.
In accordance with this invention, a coordinated dual action internal
combustion engine ignition system is provided wherein an inductive
discharge ignition system and a capacitor discharge ignition system are
inductively coupled to the secondary winding of an ignition coil through
respective primary windings and both are simultaneously activated at the
time a high ignition arc-creating potential is required to induce the high
ignition arc-creating potential in the secondary winding.
For a better understanding of the present invention, together with
additional objects, advantages and features thereof, reference is made to
the following description and accompanying single FIGURE drawing which
sets forth the dual action internal combustion engine ignition system of
this invention in schematic form.
As point of reference or ground potential is the same point electrically
throughout the system, it has been represented in the drawing by the
accepted schematic symbol and referenced by the numeral 5.
In the drawing, the dual action internal combustion engine ignition system
of this invention is set forth in schematic form in combination with
direct current potential which may be a conventional automotive type
storage battery 3, and an ignition distributor 4 having a movable
electrical contact 6, rotated in timed relationship with an associated
internal combustion engine 7, through which ignition spark energy is
directed to the spark plugs of the engine individually in sequence, in a
manner well known in the automotive art.
The internal combustion engine with which the dual action internal
combustion engine ignition system of this invention may be used is set
forth in block form, is referenced by the numeral 7 and is illustrated as
having four spark plugs 1S, 2S, 3S and 4S, each having an arc gap, as is
well known in the automotive art. It is to be specifically understood,
however, that the ignition system of this invention may be used with
internal combustion engines having more or less cylinders or with rotary
type engines.
To supply operating potential to the system, movable contact 11 of an
electrical switch 10 may be closed to stationary contact 12 to supply
battery potential across leads 13 and 14 and point of reference or ground
potential 5. Movable contact 11 and stationary contact 12 may be a pair of
normally open electrical contacts included in a conventional automotive
ignition switch of a type well known in the automotive art. For purposes
of this specification, it will be assumed that movable contact 11 is
closed to electrical contact with stationary contact 12, as is shown in
FIG. 1.
The ignition coil 15 has a magnetic core 16, a primary winding 17, another
primary winding 18 and a secondary winding 19. As is well known in the
automotive art, a flow of energizing current through either or both of
primary windings 17 and 18 produces a magnetic flux in core 16 which links
secondary winding 19 and a rapid rate of change of this linking magnetic
flux induces a high ignition potential of sufficient magnitude to strike
an ignition arc in secondary winding 19. The rapid rate of change of
magnetic flux linking secondary winding 19 may be the result of a
collapsing magnetic field upon the abrupt interruption of the flow of
energizing current through one or both of the primary windings, or it may
be the result of a rapidly increasing magnetic field upon the rapid
increase of energizing current flow through either or both of primary
windings. An ignition spark potential of sufficient magnitude to initiate
an ignition arc or spark across the arc gap of each of the spark plugs 1S,
2S, 3S and 4S is induced in secondary winding 19 by a collapsing magnetic
field upon the interruption of the flow of energizing current through
primary winding 18, in a manner well known in the automotive art, and a
rapid rise time ignition spark potential also of sufficient magnitude to
initiate an ignition arc or spark across the spark gap of each of the
spark plugs 1S, 2S, 3S and 4S is induced in secondary winding 19 by the
rapidly increasing magnetic field upon the rapid increase of energizing
current flow through primary winding 17 produced by the discharge of an
ignition capacitor 20 therethrough. Primary windings 17 and 18 are so
polarized that the rapid rate of change of magnetic flux linking secondary
winding 19 resulting from the abrupt interruption of the primary winding
18 energizing circuit and from the discharge of ignition capacitor 20
through primary winding 17 induces a high ignition arc-creating ignition
potential of the same polarity relationship in secondary winding 19.
One terminal end of the ignition coil secondary winding 19 is connected to
movable contact 6 of distributor 4 and output terminals 4a, 4b, 4c and 4d
of distributor 4 are connected to respective spark plugs 1S, 2S, 3S and
4S.
To interrupt and complete the ignition coil primary winding 18 energizing
circuit in timed relationship with engine 7, the current carrying elements
of an electrical switching device which are operable to the electrical
circuit open and closed conditions, are connected in series therein.
Without intention or inference of a limitation thereto, this electrical
switching device may be an NPN switching transistor 26 included in an
electronic ignition system 25. The current carrying elements of the
switching transistor 26, the collector-emitter electrodes, are operable to
the electrical circuit open and closed conditions in response to
electrical signals applied to the control electrode, the base electrode,
and are connected in series in the ignition coil primary winding 18
energizing circuit. The ignition coil primary winding 18 energizing
circuit may be traced from the positive polarity terminal of battery 3,
through the closed contacts of electrical switch 10, lead 14, primary
winding 18, the collector-emitter electrodes of switching transistor 26
and point of reference or ground potential 5 to the negative polarity
terminal of battery 3. The collector-emitter electrodes of switching
transistor 26 are operated to the electrical circuit open condition at the
time each spark plug of engine 7 is to be fired in response to each of a
series of ignition signals produced in timed relationship with engine 7.
The series of ignition signals may be produced in timed relationship with
engine 7 by any one of the several conventional magnetic distributors well
known in the automotive art. One example of a magnetic distributor well
known in the automotive art suitable for use with the dual action internal
combustion engine ignition system of this invention is of the variable
reluctance type disclosed and described in U.S. Pat. No. 3,254,247 Falge,
which issued May 31, 1966 and is assigned to the same assignee as is the
present invention. In the interest of reducing drawing complexity, the
variable reluctance type ignition distributor disclosed and described in
the aforementioned patent is set forth in schematic form in the drawing. A
rotor member 8 is rotated in timed relationship with the engine by the
engine in a manner well known in the automotive art within the bore of
pole piece 9. Equally spaced about the outer periphery of rotor 8 and
about the bore of pole piece 9 are a series of projections equal in number
to the number of cylinders of the engine with which the distributor and
ignition system are being used. Pole piece 9 may be made up of a stack of
a number of laminations of magnetic material secured in stacked
relationship by rivets or bolts or other fastening methods and the
magnetic flux may be provided by a permanent magnet, not shown, which may
be secured to the lower face surface thereof. As each projection of rotor
8 approaches a projection on pole piece 9, the reluctance of the magnetic
circuit between rotor 8 and pole piece 9 decreases and as each projection
on rotor 8 moves away from the projection on pole piece 9, the reluctance
of the magnetic circuit between rotor 8 and pole piece 9 increases.
Consequently, the magnetic field produced by the permanent magnet
increases and decreases as each projection on rotor 8 approaches and
passes a projection on pole piece 9, a condition which induces an
alternating current in pickup coil 2, which is magnetically coupled to
pole piece 9, of a wave form shown in the drawing above the rotor and pole
piece assembly.
During each positive polarity excursion of the series of ignition signals
induced in pickup coil 2, terminal end 2a thereof is of a positive
polarity with respect to terminal end 2b, consequently, diode 24 is
reverse biased. While diode 24 is reverse biased, base-emitter drive
current is supplied to NPN transistor 27 through resistors 28 and 29.
While base-emitter drive current is supplied to transistor 27, this device
conducts through the collector-emitter electrodes thereof to divert
base-emitter drive current from NPN transistor 30, consequently,
transistor 30 does not conduct. While transistor 30 is not conductive,
base-emitter drive current is supplied to NPN transistor 31 through
resistors 32 and 33, consequently, transistor 31 conducts through the
collector-emitter electrodes. While transistor 31 conducts through the
collector-emitter electrodes, base-emitter drive current is supplied to
NPN switching transistor 26 through resistor 34 and the collector-emitter
electrodes of transistor 31. While base-emitter drive current is supplied
to switching transistor 26, this device conducts through the
collector-emitter electrodes to complete the ignition coil primary winding
18 energizing circuit previously described. During the next negative
polarity excursion of the series of ignition signals induced in pickup
coil 2, terminal end 2a thereof is of a negative polarity with respect to
terminal end 2b, consequently, diode 24 is forward biased. At the moment
diode 24 becomes forward biased at the beginning of each negative polarity
excursion of the ignition signals, base-emitter drive current is diverted
from transistor 27 to extinguish this device. With transistor 27 not
conducting, base-emitter drive current is supplied to transistor 30
through resistors 35 and 36, consequently, transistor 30 conducts through
the collector-emitter electrodes. Conducting transistor 30 diverts
base-emitter drive current from transistor 31, consequently, transistor 31
extinguishes. When transistor 31 extinguishes, base-emitter drive current
is no longer supplied to switching transistor 26, consequently, switching
transistor 26 extinguishes to abruptly interrupt the ignition coil primary
winding 18 energizing circuit. Upon each interruption of the primary
winding 18 energizing circuit, an ignition spark potential of a
sufficiently high value to initiate an ignition arc across the arc gap of
the spark plug to which it is directed is induced in secondary winding 19
by the resulting collapsing magnetic field in a manner well known in the
automotive art. This high ignition potential is directed to the next spark
plug of engine 7 to be fired through the movable contact 6 of distributor
4. From this description, it is apparent that so long as engine 7 is
operating, the series of ignition signals induced in pickup coil 2 of the
magnetic distributor operate electronic ignition system 25 to complete and
abruptly interrupt the ignition coil primary winding 18 energizing circuit
in timed relationship with engine 7.
Upon each interruption of the ignition coil primary winding 18 energizing
circuit, the potential upon junction 40 is of a positive polarity with
respect to point of reference or ground potential 5 and is of a magnitude
substantially equal to the potential of battery 3. This potential signal
is applied through lead 39 across a voltage divider network comprised of
series resistors 41 and 42. Upon each interruption of the ignition coil
primary winding 18 energizing circuit, therefore, the potential upon
junction 43 is of a positive polarity with respect to point of reference
or ground potential 5.
The base electrodes of the input transistor 51 of a conventional monostable
multivibrator circuit 50 is connected to junction 43 between series
resistors 41 and 42 through base resistor 44. The monostable multivibrator
circuit normally operates in a stable state and may be switched to an
alternate state by an electrical signal, in which it remains for a period
of time as determined by an internal R-C timing network. After timing out,
the device spontaneously returns to the stable state. When in the stable
state, base-emitter drive current is supplied to transistor 52 through
resistor 53, potentiometer 54 and diode 55, consequently, transistor 52 is
conducting through the collector-emitter electrodes. While transistor 52
is conducting, most of the potential of battery 3 is dropped across
collector resistor 56, consequently, junction 57 is substantially ground
potential, being above ground by an amount equal to the collector-emitter
potential drop through transistor 52. Upon the interruption of the
ignition coil primary winding 18 energizing circuit, the positive polarity
potential appearing across junction 43 and point of reference or ground
potential 5 supplies base-emitter drive current to transistor 51 through
base resistor 44, consequently, transistor 51 is triggered conductive
through the collector-emitter electrodes. While transistor 51 is
conducting through the collector-emitter electrodes, most of the potential
of battery 3 is dropped across collector resistor 58 and junction 59 is of
substantially ground potential, being above ground by a potential equal to
the collector-emitter drop across transistor 51. When the potential upon
junction 59 goes to substantially ground, transistor 52 extinguishes and
timing capacitor 60 begins to charge through resistor 53, potentiometer 54
and the collector-emitter electrodes of transistor 51. When transistor 52
extinguishes, an output potential signal appears across junction 57 and
point of reference or ground potential 5 of a positive polarity upon
junction 57 with respect to point of reference or ground potential 5. When
timing capacitor 60 has become charged through the circuit previously
described, base-emitter drive current is again supplied to transistor 52
to trigger this device conductive through the collector-emitter
electrodes. With transistor 52 conductive through the collector-emitter
electrodes, the potential upon junction 57 is again substantially ground
and is fed back to the base electrode of transistor 51 to extinguish this
device. From this description, it is apparent that monostable
multivibrator circuit 50 is an electrical circuit of the type which is
electrically triggerable to a condition of operation during which a
potential signal is present upon the output circuit thereof for a
predetermined period of time and is then terminated and that monostable
multivibrator circuit 50 is so triggered in response to each interruption
of the ignition coil primary winding 18 energizing circuit.
When monostable multivibrator circuit 50 is electrically triggered to the
alternate state upon each interruption of the ignition coil primary
winding 18 energizing circuit, the positive polarity potential upon
junction 57 reverse biases diode 65. While diode 65 is reverse biased,
base-emitter drive current is supplied to NPN transistor 66 through
resistors 67 and 68, consequently, transistor 66 is triggered conductive
through the collector-emitter electrodes thereof. The base electrode of
transistor 69 is connected to junction 70 between resistors 72 and 73 of a
voltage divider network comprised of collector resistor 71 and resistors
72 and 73. As the potential upon junction 70 is of a sufficient magnitude
to supply base-emitter drive current through NPN transistor 69, this
device conducts through the collector-emitter electrodes when transistor
66 is triggered conductive. While transistors 66 and 69 are conducting,
base-emitter drive current is supplied to the Darlington switching
transistor pair 75a and 75b through collector resistor 71 and the
collector-emitter electrodes of conducting transistor 66 to trigger the
Darlington pair of transistors conductive through the collector-emitter
electrodes. When transistors 75a and 75b are conducting through the
collector-emitter electrodes, an energizing circuit is established for the
primary winding 81 of a transformer 80 through a circuit which may be
traced from the positive polarity terminal of battery 3, through the
closed contacts of switch 10, lead 13, primary winding 81 of transformer
80, the collector-emitter electrodes in parallel of the transistor
Darlington pairs 75a and 75b, current sensing resistor 74 and point of
reference or ground potential 5 to the negative polarity terminal of
battery 3. When monostable multivibrator circuit 50 spontaneously reverts
to the stable state, base-emitter drive current is drained from transistor
66 through diode 65 and the collector-emitter electrodes of transistor 52
of monostable multivibrator circuit 50, consequently, transistor 66
extinguishes. When transistor 66 extinguishes, the circuit through which
base-emitter drive current is supplied to the transistor Darlington pair
75a and 75b is interrupted to extinguish these devices. When the
transistor Darlington pair 75a and 75b extinguish, the energizing circuit,
previously described, for primary winding 81 of transformer 80, is
abruptly interrupted. Upon the abrupt interruption of the energizing
circuit for primary winding 81, a high potential, of the order of 400
volts, is induced in secondary winding 82 of a positive polarity upon
terminal end 82b thereof with respect to terminal end 82a. This potential
charges ignition capacitor 20 through diode 83 in a manner well known in
the art. From this description, it is apparent that the charge potential
generating circuitry comprising transistors 66 and 69, transistor
Darlington pair 75a and 75b and transformer 80 is under the control of the
potential output signal of monostable multivibrator circuit 50 for
producing a direct current potential in response to the termination of the
potential output signal of monostable multivibrator circuit 50 and for
impressing the direct current potential across ignition capacitor 20 to
place a charge thereupon.
Transistor 69 is not absolutely necessary to the operation of the charge
potential generating circuitry just described but aids in the turn-off of
the transistor Darlington pair 75a and 75b with conditions of high
temperature.
The current limiting circuitry comprising NPN transistor 85, resistors 86
and 87 and current sensing resistor 74 are not absolutely necessary but
may be employed for the purpose of limiting the transformer primary
winding 81 energizing current to a preselected value. The ohmic value of
current sensing resistor 74 is selected to produce a potential drop
thereacross of a magnitude sufficient to break down the base-emitter
junction of NPN transistor 85 with a current flow therethrough equal to
the preselected maximum transformer primary winding 81 energizing current.
When this potential reaches a level of sufficient magnitude to break down
the base-emitter junction of transistor 85, base-emitter current is
supplied to this device to trigger it conductive through the
collector-emitter electrodes. With transistor 85 conducting through the
collector-emitter electrodes, transistor 66 is pulled out of saturation
and thereafter conducts at a level sufficient to provide the base-emitter
drive current to transistor Darlington pair 75a and 75b which will result
in the amount of transformer primary winding 81 energizing current flow
equal to the preselected maximum.
Upon the next interruption of the ignition coil primary winding 18
energizing circuit, the potential appearing across junction 43 and point
of reference or ground potential 5 triggers monostable multivibrator
circuit 50 to the alternate state to activate the charge potential
generating circuitry previously described to complete the energizing
circuit for primary winding 81 of transformer 80 and a trigger signal is
supplied through resistor 88 and lead 89 to the gate electrode of a
silicon controlled rectifier 90 to trigger this device conductive through
the anode-cathode electrodes in a manner well known in the electronics
art. When silicon controlled rectifier 90 is triggered conductive through
the anode-cathode electrodes, a discharge circuit for ignition capacitor
20 is established through secondary winding 17 of ignition coil 15 which
may be traced from the plate of capacitor 20 connected to junction 91,
through the anode-cathode electrodes of silicon controlled rectifier 90
and primary winding 17 to the other plate of ignition capacitor 20. It is
to be specifically understood that silicon controlled rectifier 90 may be
replaced by any electrically operable switching device which may be
operated to the electrical circuit closed condition in response to an
electrical signal. From this description it is apparent that a discharge
circuit for ignition capacitor 20 including primary winding 17 of ignition
coil 15 is established through silicon controlled rectifier 90 which is
operated to the electrical circuit closed condition in response to each
interruption of the ignition coil primary winding 18 energizing circuit.
After the first complete ignition signal cycle, upon each subsequent
negative polarity excursion of the ignition signal cycles, the ignition
coil primary winding 18 energizing circuit is abruptly interrupted and
simultaneously, the discharge circuit for ignition capacitor 20 is
established through silicon controlled rectifier 90 to provide for the
discharge of ignition capacitor 20 through primary winding 17 of ignition
coil 15. The rapid rate of change of magnetic flux linking secondary
winding 19 as a result of the collapsing magnetic field produced by the
interruption of the ignition coil primary winding 18 energizing circuit
and the rapid change of magnetic flux linking secondary winding 19 as a
result of the increasing magnetic field produced by the discharge current
of ignition capacitor 20 through ignition coil primary winding 17 induces
a high ignition arc-creating potential in secondary winding 19. As the
high ignition potential induced in secondary winding 19 by the discharge
of capacitor 20 through primary winding 17 is of a rapid rise time but
relatively short duration and the high ignition potential induced in
secondary winding 19 as a result of the interruption of the energizing
circuit for primary winding 18 has a slower rise time but a substantially
longer duration, the simultaneous discharge of ignition capacitor 20 and
interruption of the ignition coil primary winding 18 energizing circuit
results in the steep wave form produced by capacitor 20 being superimposed
upon the slower rising wave form produced by the interruption of ignition
coil primary winding energizing circuit 18 which results in a high
ignition arc-creating potential having a rise time much faster than that
produced by a purely inductive system and of a duration much longer than
that produced by a purely capacitor discharge system.
The ignition coil primary windings 17 and 18 are so polarized that the
rapid rate of change of magnetic flux linking secondary winding 19
resulting from the abrupt interruption of the primary winding 18
energizing circuit and from the discharge of ignition capacitor 20 through
primary winding 17 induces respective potentials of the same polarity
relationship in ignition coil secondary winding 19.
While a preferred embodiment of the present invention has been shown and
described, it will be obvious to those skilled in the art that various
modifications and substitutions may be made without departing from the
spirit of the invention which is to be limited only within the scope of
the appended claims.
* * * * *
|
|
 |
|
 |
Description |
|
