U.S. patent number 3,855,973 [Application Number 05/265,046] was granted by the patent office on 1974-12-24 for synchronizing means for sequential fuel injection.
This patent grant is currently assigned to International Harvester Company. Invention is credited to Bruce A. Scofield.
United States Patent |
3,855,973 |
Scofield |
December 24, 1974 |
SYNCHRONIZING MEANS FOR SEQUENTIAL FUEL INJECTION
Abstract
Synchronizing means for sequential fuel injection wherein valve
actuator means are energized in response to signals from sequencing
and timer circuits. Triggering signals are applied to the
sequencing circuit, including an indexing pulse developed in
predetermined phase relation to each and every power stroke of the
engine and a reset pulse in predetermined phase relation to the
power stroke of a predetermined one of the engine cylinders. The
sequencing circuit includes a digital counter which is indexed by
the index pulses and which is reset by the reset pulses. In one
embodiment, an index pulse generator is connected to ignition pulse
generating means of the engine, preferably in circuit with an
ignition coil primary, and a reset pulse generator is connected to
one output of the distributor. In another embodiment, the index and
reset pulses are generated inductively in response to rotation of
engine parts.
Inventors: |
Scofield; Bruce A. (Fort Wayne,
IN) |
Assignee: |
International Harvester Company
(Chicago, IL)
|
Family
ID: |
23008726 |
Appl.
No.: |
05/265,046 |
Filed: |
June 21, 1972 |
Current U.S.
Class: |
123/490; 123/476;
123/146.5A; 123/475 |
Current CPC
Class: |
H03K
17/28 (20130101); F02D 41/365 (20130101) |
Current International
Class: |
F02D
41/36 (20060101); H03K 17/28 (20060101); F02D
41/32 (20060101); F02b 003/00 () |
Field of
Search: |
;123/32EA,119R,146E,146B,146AC |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myhre; Charles J.
Assistant Examiner: Cox; Ronald B.
Attorney, Agent or Firm: Krubel; Frederick J. Harman; Floyd
B.
Claims
What is claimed is:
1. A fuel injection control system for an engine including a
plurality of cylinders and fuel injection valve means associated
with each cylinder for injection of fuel for flow into each
cylinder during the intake stroke thereof, electrically energizable
actuator means for each of said fuel injector valve means, spark
plug means for each cylinder, ignition pulse generating means for
generating an ignition pulse in predetermined phase relation to
each and every power stroke of the engine, and distributor means
for applying said ignition pulses to said spark plug means in
sequence, said control system comprising: a sequencing circuit for
supplying sequencing signals in synchronized relation to intake
strokes of the engine, timer means for supplying timing signals,
means responsive to said sequencing and timing signals for
energizing said actuator means, said sequencing circuit having a
plurality of stable states respectively corresponding to said
actuator means and being arranged to be indexed from one state to
another in a predetermined order and to develop in each of said
states a sequencing signal for control of the corresponding
actuator means in response to a timing signal from said timer
means, index pulse means for supplying to said sequencing circuit
an index pulse in predetermined phase to each and every power
stroke of the engine to index said sequencing circuit from one
state to another, and reset pulse means for supplying to said
sequencing circuit a reset pulse in predetermined phase relation to
the power stroke of a predetermined one of the engine cylinders to
reset said sequencing circuit to a predetermined initial state,
said index pulse means being arranged for coupling to said ignition
pulse generating means to develop and index in response to each
ignition pulse, and said reset pulse means being arranged for
coupling to said distributor means to develop a reset pulse in
response to each ignition pulse applied to the spark plug means for
said predetermined one of the engine cylinders, said index pulse
means comprising a first monostable multivibrator, said reset pulse
means comprising a second monostable multivibrator, said first and
second multivibrators being triggered in response to ignition
pulses from said ignition pulse generating means and said
distributor means.
2. In a system as defined in claim 1, said sequencing circuit
comprising digital counter means, means for applying said index
pulses from said index pulse means to said digital counter means to
advance the count thereof in response to each index pulse, and
means for applying said reset pulses to said counter means to
insure reset of said counter means to a predetermined condition in
response to each reset pulse.
3. In a system as defined in claim 1, at least one of said
multivibrators being operative as a delay circuit such as to
provide a phase-displaced relation between each reset pulse and the
corresponding index pulse.
4. In a system as defined in claim 1, wherein the ignition pulse
generating means comprises an ignition coil having primary and
secondary winding means, and means providing a connection from said
primary winding means to a voltage source and arranged for
periodically breaking said connection to develop a high voltage
ignition pulse in said scondary winding means, said index pulse
means including resistance means in series with said primary
winding means.
5. In a system as defined in claim 1, said reset pulse means
comprising ionizable discharge means, and a high resistance
connection from said discharge means to said distributor means.
Description
This invention relates to synchronizing means for sequential fuel
injection and more particularly to synchronizing means which permit
highly accurate control while being economically manufacturable and
very durable and reliable.
BACKGROUND OF THE INVENTION
Sequential fuel injection systems have heretofore been proposed
using one electrically operated valve for each cylinder to allow
flow of a controlled amount of fuel during each intake stroke, with
the amount of fuel being controlled by controlling the duration of
electrical pulses applied through distributor means to allocate the
application of the pulses to the injector valves in accordance with
the firing order of the invention. Such systems have not been
entirely satisfactory with respect to construction, operation and
reliability. For example, the distributor means have generally
required the use of rotating contacts having sliding engagement
with commutator segments and/or mechanically operated switches
operated from an engine part for transmitting the pulses or
developing control signals.
SUMMARY OF THE INVENTION
This invention was evolved with the general object of overcoming
the disadvantages of prior art systems and of providing a system
using electronic circuitry for controlling the sequential
energization of injector valves and in which the operation of the
electronic circuitry is synchronized with the operation of the
engine in a highly accurate and reliable manner.
Another object of the invention is to provide a synchronizing
arrangement for sequential fuel injection using components which
are rugged and durable while being economically manufacturable.
In a system according to this invention, injector valve actuators
are controlled from timing signals and from control signals from a
sequencing circuit to which triggering signals are applied from
triggering means including index pulse means for supplying an index
pulse in predetermined phase relation to each and every power
stroke of the engine and including reset pulse means for supplying
reset pulses in predetermined phase relation to the power stroke of
a predetermined one of the engine cylinders. Through the
application of such index and reset pulses, the operation of the
sequencing circuitry is reliably synchronized with the operation of
the engine and is accurately controlled, to insure that the fuel is
injected into the correct engine cylinder and in proper phase
relation to the intake stroke of the cylinder.
In one preferred embodiment, the indexed pulse means is coupled to
the ignition pulse generating means of the engine to develop an
index pulse in response to each ignition pulse and the reset pulse
means is arranged for coupling to distributor means of the engine
ignition system to develop a reset pulse in response to each
ignition pulse applied to the spark plug of a predetermined one of
the engine cylinders. With this arrangement, the ignition system of
the engine performs a dual function and the number of components
required is minimized. No addition of switching contacts or the
like is required and a high degree of reliability is obtained.
In another embodiment, the index and reset pulse means respond to
pulses from pulse generating means coupled to the engine, separate
from the ignition system. Preferably, and in accordance with a
specific feature, such pulse generator means generate pulses from
magnetic field changes in a manner such that no contacts are
required and insuring high reliability.
Additional very important features of the invention relate to the
combination of the index and reset pulse means with sequencing
means including digital counter means arranged to count or be
indexed by the index pulses and to be reset to a predetermined
condition by each reset pulse. With this combination, the required
control signals can be generated electronically with no switching
contacts or the like. As claimed in a related application of Bruce
A. Scofield, Ser. No. 265,047, filed June 21, 1972, now U.S. Pat.
No. 3,820,198, such electronically generated control signals,
together with electronically generated timing signals, can be
applied through gate means to transistor driver stages for the
injector valve actuators, the use of the digital counter means
being also highly advantageous in conjunction with such electronic
switching circuitry.
Further features relate to electronic circuitry associated with the
synchronizing means and operative to generate the index and reset
pulses in a uniform, accurate and reliable manner.
This invention contemplates other objects, advantages and features,
which will become more fully apparent from the following detailed
description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a sequential fuel injection system
for a four cylinder engine, incorporating switching circuitry
according to the invention;
FIG. 2 is a block diagram of sequence and driver circuits of the
system of FIG. 1;
FIG. 3 is a circuit diagram of counter, decoder, gating and driver
circuitry shown in block form in FIG. 2;
FIG. 4 is a wave form diagram for explanation of the circuitry of
FIGS. 2 and 3;
FIG. 5 shows the circuits of delay multivibrators and a flip-flop,
shown in block form in FIG. 2, and also shows schematically means
for applying triggering signals, from the engine ignition system;
and
FIG. 6 shows schematically a modified means of applying triggering
signals.
Reference numeral 10 generally designates a sequential fuel
injection system designed for a four cylinder engine, incorporating
synchronizing means and associated circuitry constructed in
accordance with the principles of the invention. An individual
solenoid-operated injection nozzle or valve is provided for each
cylinder of an engine and each valve is opened once during every
revolution of the engine cam shaft, or once during every other
revolution of the crank shaft, in the case of a four cycle engine.
In the system 10, designed for a four-cylinder engine, there are
four injection valves, 11-14, FIG. 2, which may be mounted on an
intake manifold 15 of an engine 16 in the manner as shown
diagrammatically in FIG. 1. As also shown in FIG. 1, the injection
valves are connected to a header 18 which is connected through a
filter 19 to the outlet of a pump 20 having an inlet connected to a
fuel tank 21. A pressure regulator 22 is provided between the
header 18 in the fuel tank 21 to maintain the pressure in the
header at a substantially constant value which may be on the order
of 40 PSI, by way of example.
The injection valves 11-14 are connected to a driver circuit 24
controlled from a sequence circuit 25. In accordance with the
invention, the sequence circuit 25 receives control or reset and
triggering or index signals from a distributor 26 and an ignition
coil 27 of the engine and controls the time intervals in which the
valves 11-14 may be energized, to synchronize the injection of fuel
in relation to the intake strokes of the respective cylinders. The
sequence circuit 25 is also connected through lines 29 and 30 to a
timer 31 which is controlled from a computer 32.
Computer 32 controls the timer 31 and through the sequence and
driver circuits 25 and 24, the time duration of each opening of
each injection valve is controlled, the control being a function of
the prevailing operating conditions at the time of injection. In
the illustrated arrangement, the computer 32 receives pulses from
the ignition coil 27 to develop a speed signal and is connected to
switches 33 and 34 mounted on a throttle 35 of the engine 16,
switch 33 being operated when the throttle is closed and switch 34
being operated when the throttle is wide open. Computer 32 is also
connected to a sensor 36 which senses intake manifold absolute
pressure, to a sensor 37 which senses coolant temperature and to a
sensor 38 which senses air temperature, as diagrammatically
illustrated. The computer 32 may also contain circuitry for sensing
acceleration and also the rate of change of intake manifold
absolute pressure. In response to such sensed operating conditions,
the computer 32 may develop an analog voltage output which controls
the duration of a pulse generated by timer 31 and applied to the
sequence circuit through line 29, the beginning of each pulse being
determined by a triggering signal applied through line 30. It
should be understood that the timer 31 and computer 32 are not, by
themselves, part of the present invention, and, so far as concerns
the synchronizing means and associated circuitry of this invention,
any suitable means could be employed to generate a timing signal or
pulse of controllable duration. By way of example, the duration of
the timing signal or pulse may typically be on the order of from 2
to 12 milliseconds.
Referring now to FIG. 2, the solenoids of the injection valves
11-14 are connected between ground and outputs of four driver
stages 41-44 connected to a power supply terminal 45 to which
battery voltage of on the order of twelve volts may be supplied.
Inputs of the driver stages 41-44 are connected to the outputs of
four AND gates 47-50 having inputs connected together into the
output of a flip-flop 51 and having additional inputs connected
through a decoder 52 to outputs of a two-bit counter 53. Inputs of
the flip-flop 51 and of the counter 53 are connected to the output
of a delay monostable multivibrator 54 having an input connected
through a line 55 to the ignition coil 27. An additional input of
the counter 53 is connected to the output of a second monostable
delay multivibrator 56 having an input connected through a line 57
to the distributor 26.
In the general operation of the system, index signals responsive to
ignition pulses are applied through the delay multivibrator 54 to
the counter 53 to advance the count thereof and also to the
flip-flop 51 which is then placed in a set condition, a signal
being then applied through line 30 to the timer 31 to initiate
operation thereof. Timer 31 then generates a pulse of controlled
length at the termination of which a signal on line 29 resets the
flip-flop 51. When the flip-flop 51 is set, a signal is applied
through one of the AND gates 47-50, depending upon the condition of
the counter 52, to one of the driver stages 41-44, to energize one
of the injection valves 11-14 for a time interval corresponding to
the timing pulse applied from the timer 31. The reset signal
applied from the distributor 26 through the delay multivibrator 56
to the counter 53 is for the purpose of correlating the operation
of the counter 53 to the firing sequence of the engine.
Although the details of the circuits of the driver stages 41-44,
gates 47-50, decoder 52 and counter 53 are not essential to an
understanding of the synchronizing means and associated circuitry
of this invention, the circuits and their operation are illustrated
and described in detail to facilitate understanding of the
synchronizing operation and an understanding of the advantages
obtained from the combination of synchronizing means and circuitry
with switching circuitry in a full injection system.
Referring to FIG. 3, the driver stages 41-44 include power
transistors 61-64 having emitters connected to the injection valves
11-14 and having collectors connected through resistors 65-68 to
the power supply terminal 45. The bases of the transistors 61-64
are connected through resistors 69-72 to the power supply terminal
45 and to the collectors of transistors 73-76 the emitters of which
are connected to ground and the bases of which are connected
through resistors 77-80 to a line 81 which is connected through a
resistor 82 to ground and which is also connected to an emitter of
a transistor 83 the collector of which is connected to the power
supply terminal 45 and the base of which is connected through a
resistor 84 to the output of the flip-flop 51. The bases of the
transistors 61-64 are additionally connected to the collectors of
transistors 85-88 and also to the collectors of transistors
89-92.
The bases of the driver transistors 61-64 are also connected to the
collectors of transistors 85-88 and to the collectors of
transistors 89-92, the emitters of the transistors 85-92 being
connected to ground.
The bases of transistors 85-92 are connected through resistors
93-100 to outputs of two flip-flops 101 and 102, together forming
the counter 53. A reset output of flip-flop 101, on line 103, is
connected to resistors 93 and 99 and also to an input line of
flip-flop 102. A set output of flip-flop 101, on line 104, is
connected to resistors 94 and 96. A reset output of flip-flop 102,
on line 105, is connected to resistors 97 and 98. A set output of
flip-flop 102, on line 106, is connected to resistors 99 and 100. A
set input of both flip-flops 101 and 102 is connected through a
line 108 to the output of the delay multivibrator 56. A triggering
input of flip-flop 101 is connected through a capacitor 109 to the
output of the delay multivibrator 54. Power supply terminals for
both flip-flops 101 and 102 are connected to the junction between
two resistors 111 and 112, connected between ground and the power
supply terminal 45.
FIG. 4 graphically illustrates the operation of the circuitry of
FIG. 3. The top four representations, numbered: "1," "2," "3" and
"4" indicate the intake, compression, power and exhaust strokes for
the engine cylinders corresponding to injection valves 11-14. It is
noted that these numbers do not correspond directly to the
conventional numbering of engine cylinders from front to rear. With
an engine having a 1, 3, 4, 2 firing order, the numbers 1, 2, 3 and
4 in FIG. 4 may respectively correspond to the numbers 3, 4, 2 and
1 cylinders, numbered from front to rear in the engine.
Wave form 116 indicates the signal applied from the distributor 26
through the line 57 to the input of delay multivibrator 56. The
signal is in the form of an ignition pulse applied to the front
cylinder, corresponding to the injection valve 13, being
approximately coincident with the start of the power stroke of that
cylinder which is the number 3 cylinder using the desigation of
FIG. 4. Wave form 117 indicates the signal developed at the output
of the delay multivibrator 56 which is applied through the line 108
to the set inputs of both flip-flops 101 and 102. The signal is in
the form of a short pulse having a trailing negative-going edge
delayed by certain time interval after the triggering pulse applied
from the distributor. When the trailing negative-going edge is
applied to the set inputs of the flip-flops 101 and 102, it insures
that they will be placed in a set condition, if not already in that
condition.
Wave form 118 is that of the signal applied through line 55 to the
delay multivibrator 54 from the ignition coil 27, this signal being
in the form of an ignition pulse developed at a time approximately
coincident with the start of every power stroke.
Wave form 119 is that of the signal developed at the output of the
delay multivibrator 54 which is applied through the capacitor 109
to the triggering signal input to the flip-flop 101. This signal
was in the form of a series of pulses having negative-going
trailing edges delayed by short time interval after the applied
ignition pulses. Such trailing edges cause the flip-flop 101 to
change its state from one state to the other.
Wave form 120 is that of the set output line 104 of the flip-flop
101 which is caused to go "high" by the first illustrated pulse
wave form 119, "low" by the second, again "high" by the third,
again "low" by the fourth and again "high" by the fifth. It is
noted that the trailing edge of the pulse of wave form 117 occurs
after the trailing edge of the first illustrated pulse of wave form
119 and since flip-flop 101 is already in a set condition, the
pulses of wave form 117 have no effect. However, if during starting
conditions, for example, the flip-flops 101 and 102 were not in set
conditions when the first pulse of wave form 117 is applied, the
first pulse would then operate to insure placing both flip-flops in
a set condition at this point of the operation.
Wave form 121 is that of a signal at the reset output line 103 of
the flip-flop 101 while wave forms 122 and 123 are of the signals
at the set and reset output lines 106 and 105 of the flip-flop 102.
It will be noted that the flip-flop 102 is shifted from one state
to the other in response to negative-going portions of the signal
applied thereto from the reset line 103 of the flip-flop 101,
indicated by wave form 121.
Wave form 124 is that of the signal at the output of the flip-flop
51 which is shifted "low" by the negative-going trailing edges of
the pulses from delay multivibrator 54 (wave form 119) and which is
shifted "high" by a signal applied from timer 31 through line 29,
it being noted that the operation of the timer 31 is initiated when
the flip-flop 51 is shifted "low," by a signal applied through line
30.
Wave forms 125-128 are those of the signals applied to the
injection valves 11, 12, 13 and 14, which are in the form of
positive pulses during the respective intake strokes of the
cylinders with which valves 11-14 are associated. It is noted that
during the first 180.degree. of engine rotation, the signals
applied from the reset output lines 103 and 105 of the flip-flops
101 and 102, wave forms 121 and 123, are "low." Such signals are
applied through the resistors 93 and 97 to the bases of transistors
85 and 89 which are cut off. The timing signal, wave form 124, is
also "low" during part of the first 180.degree. of engine rotation
and this signal is applied through the transistor 83, operative as
an emitter-follower, to the line 81 and from line 81 through the
resistor 77 to the base of transistor 73, which is thus also cut
off. With all three transistors 73, 85 and 89 cut off, the
potential of the base of the transistor 61 rises toward the
potential of the power supply terminal 45, being limited only by
the flow of base-emitter current through the resistor 69, and the
driver transistor 61 conducts heavily through the injection valve
11, so long as the timing signal, wave form 124, is "low."
During the first 180.degree. of engine rotation, "high" signals are
applied to the bases of transistors 86, 87 and 88, and also 92,
which are rendered conductive to place the potentials of the bases
of the driver transistors 62, 63 and 64 at values close to ground
potential. The driver transistors 62, 63 and 64 are thus
non-conductive, and no signal is applied to the injection valves
12, 13 and 14.
During the next 180.degree. of engine rotation, the signals applied
to the bases of transistors 86 and 90 are both low, and the driver
transistor 62 is rendered conductive for the duration of the timing
signal from flip-flop 51 (wave form 124). At this time, the inputs
to transistors 85, 87 and 88 are "high" preventing conduction of
the transistors 61, 63 and 64.
In a similar fashion, the driver transistors 63 and 64 are rendered
conductive during the third and fourth 180.degree. intervals of
engine rotation, for time intervals equal to the duration of the
timing signal from flip-flop 51. It is noted that the wave forms
125-128, as illustrated, are rectangular pulses but in actual
operation, the wave forms are distorted due to the inductance of
the solenoid actuators and due to inertial effects. Because of such
inductance and inertial effects the actual opening of the injection
valve is delayed to take place after the leading edge of the
applied pulse and likewise, the actual closing of the valve may be
delayed. However, the actual time of opening of each injection
valve and thereby the amount of fuel injected are proportional to
the duration of the timing pulse, to within close limits of
accuracy.
It is also noted that each injection valve may be opened throughout
nearly 180.degree. of crankshaft rotation which is important in
that the required instantaneous rate of flow through each injection
valve or nozzle, during the time it is opened, under maximum total
flow of conditions, is reduced since the valve is open for a longer
time interval. The requirements as to design and construction of
the valve are not nearly as stringent as they would be if the valve
had to be opened for short periods of time with a correspondingly
higher required instantaneous rate of flow. Also, variations in
opening and closing times of the valves, as well as variations in
the accuracy of generation of the timing signals, have a reduced
effect on overall accuracy. By way of example, the system may be
designed for a 6 millisecond maximum pulse length each 180.degree.
crank rotation, for operation and up to 5,000 RPM.
It is noted that FIG. 2 illustrates the functional operations
performed whereas FIG. 3 illustrates the implementation of such
functions in an actual circuit. In FIG. 2, the functions of the
decoder 52, illustrated in block form, is to produce a number of
outputs in sequence, the number being equal to the number of engine
cylinders, and the function of the illustrated AND gates 47-50 is
to combine such outputs of the decoder 52 with the output of the
timing flip-flop 51. In the actual circuit of FIG. 3, these
functions are implemented by using three input NOR gates for each
of the driver transistors 61-64. For example, transistors 73, 86
and 89 and associated circuit elements form a three input NOR gate
for the driver transistor 61, requiring three "low" inputs to
produce a "high" output at the base of driver transistor 61. In a
strict sense, there is no AND gate as such in that there is no
individual circuit in which all inputs must have the same value to
make the output equal to any of the inputs. However, in a broader
sense, the functional operations are nevertheless performed, in
that the transistors 85 and 89 perform a decoding function,
allowing the collectors thereof to go toward "high" only when the
flip-flops 101 and 102 are in prescribed states, and through the
common connection of the collectors of transistors 85, 89 with the
collector of the transistor 73, an AND function is performed in
that the decoding function must be performed and the timing
flip-flop 51 must be in a certain state in order to make the output
have a certain value. It will be understood that other types of
logic circuit elements might be used to implement the prescribed
functions and that reference herein to AND and OR gates is intended
in a functional sense and not as limiting the invention to
particular circuits for implementation of the prescribed
functions.
Referring to FIG. 5, the flip-flop 51 comprises a pair of
transistors 131 and 132 having emitters connected together into a
resistor 133 to ground and having collectors connected to a power
supply terminal 134 through resistors 135 and 136. The bases of
transistors 131 and 132 are connected through resistors 137 and 138
and through resistors 139 and 140 to the collectors of the
transistors 132 and 131, respectively, capacitors 141 and 142 being
connected in parallel with the resistors 139 and 140. The base of
transistor 131 is additionally connected through a diode 143 to a
circuit point 144 which is connected to a resistor 145 to the
collector of the transistor 131 and which is connected through a
capacitor 146 to the output of the delay multivibrator 54.
Similarly, the base of the transistor 132 is additionally connected
through diode 147 to a circuit point 148 which is connected through
a resistor 149 to the collector of the transistor 132 and which is
connected through a coupling capacitor 150 to the line 29 from the
timer 31.
In operation, the transistor 131 is normally conductive while the
transistor 132 is cut off. When a negative-going signal is applied
from the output of the delay multivibrator 54, through the coupling
capacitor 146 and the diode 143, the transistor 131 is rendered
non-conductive while the transistor 132 is rendered conductive,
developing a negative-going signal at the collector thereof applied
through the line 30 to the timer 31 to initiate operation thereof.
After a certain time interval, depending upon the control signals
applied to the timer 31, a negative-going signal is applied from
the timer through the line 29, capacitor 150 and diode 147 to the
base of the transistor 132, rendering the transistor 132
non-conductive and the transistor 131 conductive, thus restoring
the initial condition. The collector of the transistor 132 is
connected to the AND gates 47-50 (through resistor 84 to the base
of the transistor 83, in the circuit of FIG. 3) to apply a drive
pulse to the appropriate injector valve, depending upon the
condition of the sequencing circuitry, including flip-flops 101 and
102.
The delay multivibrator 54 comprises a pair of transistors 151 and
152 having emitters connected to ground and having collectors
connected through resistors 153 and 154 to the power supply
terminal 134. The base of the transistor 152 is connected through a
resistor 155 to a circuit point 156 which is connected through a
capacitor 157 to the collector of the transistor 151 and which is
connected through an adjustable resistor 158 to the power supply
terminal 134. The base of the transistor 151 is connected through a
resistor 159 to the collector of the transistor 152 and is also
connected through a resistor 160 and through the line 55 to the
ignition system.
In operation of the delay multivibrator 54, the transistor 151 is
normally non-conductive while the transistor 152 is normally
conductive. When a positive pulse is applied through line 55 and
the resistor 160 to the base of the transistor 151, the transistor
151 conducts, cutting off the transistor 152 through the connection
of the collector of transistor 151 through capacitor 157 and
resistor 155 to the base of the transistor 152. The charge of the
capacitor 157 is then gradually changed through current flow
through the adjustable resistor 158 and after a certain time
interval, depending upon a position of adjustment of the resistor
158, the transistor 152 again conducts, cutting off the transistor
151. Thus a positive pulse of predetermined duration is developed
at the collector of the transistor 152, which is applied to the
flip-flop 51 and also through the capacitor 109 to the flip-flop
101, the negative-going or trailing edge of the pulse being
effective to trigger the flip-flop 51 and also to trigger the
flip-flop 101.
The delay multivibrator 56 comprises a pair of transistors 163 and
164 having emitters connected to ground and having collectors
connected through resistors 165 and 166 to the power supply
terminal 134. The base of the transistor 163 is connected through a
resistor 167, in parallel with a capacitor 168, to the collector of
the transistor 164. The base of the transistor 164 is connected
through the line 57 to the ignition circuit and is also connected
through a resistor 169 to a circuit point 170 which is connected
through a capacitor 171 to the collector of the transistor 163 and
through an adjustable resistor 172 to the power supply terminal
134. This circuit operates in a manner similar to the circuit of
the delay multivibrator 54, the transistor 163 being normally
non-conducting and the transistor 164 being normally conducting.
When a negative pulse is applied to the base of the transistor 164
through the line 57, transistor 164 is cut off and transistor 163
becomes conducting and remains conducting until the charge of
capacitor 171 is changed through current flow through the resistor
172 to an extent sufficient to render the transistor 164 again
conducting whereupon the transistor 163 is cut off.
Thus a positive pulse of predetermined duration, determined by the
adjustment of the resistor 172, is developed at the collector of
the transistor 164. This pulse is applied through a capacitor 173
to a circuit point which is connected through a resistor 174 to
ground, through a resistor 175 to the power supply terminal 134 and
directly to the base of a transistor 176. The collector of the
transistor 176 is connected to a power supply terminal 177 while
the emitter thereof is connected to the line 108 and through a
resistor 178 to ground. Transistor 176 operates as an
emitter-follower, developing a positive pulse on the line 108, the
negative-going or trailing edge of the pulse being effective to
reset the flip-flops 101 and 102.
In the circuit arrangement of FIG. 5, the triggering signals for
developing the index and reset pulses are developed from the engine
ignition system which may be of conventional construction as
diagrammatically illustrated, including the ignition coil 27 having
primary and secondary windings 181 and 182. The primary winding 181
is connected between the positive terminal of a battery 183 and a
movable breaker contact 184 which is actuated by a four lobe cam
185 driven from the cam shaft of the engine, the contact 184 being
periodically moved out of engagement with a grounded contact 186 to
interrupt current flow through the primary 181 and to induce a high
voltage in the secondary winding 182. Capacitor 187 is connected
between contacts 184 and 186.
The ignition system further includes the distributor 26 comprising
a rotating contact 190 sequentially engaged with contacts 191-194
which are respectively connected to spark plugs 195-198. Contact
190 is connected to one end of the secondary winding 182 the other
end of which is connected to one end of the primary winding 181 and
to the contact 184, connected through the capacitor 187 to
ground.
In the arrangement of FIG. 5, the triggering pulses for the
multivibrator 54 are developed by inserting a resistor 200 between
the positive terminal 188 and of the primary winding 181 which is
connected through a coupling capacitor 201 to the line 55. When the
breaker contacts 184, 186 are opened, a voltage pulse is developed
at the junction between resistor 200 and the primary winding 181
which is applied through the coupling capacitor 201, line 55 and
resistor 160 to the transistor 151 to trigger the transistor 151
into conduction.
To develop the triggering pulses on the line 57, it is connected
through a neon lamp 202 and a resistor 203 to the distributor
contact 191 for a predetermined one of the engine cylinders.
Resistor 203 may have a relatively high value, 6 megohms, for
example, and a capacitor 204 may preferably be connected between
line 57 and ground. When a high voltage pulse is applied to the
distributor contact 191, the neon lamp 202 conducts and discharges
the capacitor 204 to trigger the transistor 164 to a non-conductive
state and to initiate development of a pulse on the output line 108
the negative-going or trailing edge of which resets the flip-flops
101 and 102 to a predetermined state in a manner as described
above.
FIG. 6 illustrates a modified arrangement for developing the
triggering pulses. In this arrangement, line 55 is connected
through a resistor 206 to ground and through a capacitor 207 to one
end of a coil 208 of a pick-up unit 210 may comprise a pair of pole
pieces 211 and 212 with a small permanent magnet 213 therebetween.
The ends of the pole pieces 211 and 212 are spaced a short distance
apart and are in proximity to the annular path of movement of the
outer ends of four teeth 215-218 of magnetic material, carried by a
rotor 220 which may be driven from the cam shaft of the engine. As
each of the teeth 215-218 pass in proximity to the ends of the pole
pieces 211 and 212, the magnetic flux linking the coil 208 is
abruptly increased and then decreased, generating positive and
negative pulses, the positive pulses being effective to trigger the
transistor 151 into conduction.
The line 57 in FIG. 6 is connected through a resistor 221 to ground
and through a capacitor 222 to a coil 223 of a pick-up unit 224,
the other end of coil 223 being grounded. Pick-up unit 224 may be
substantially identical to the unit 210 and is in proximity to the
path of movement of a single tooth 225 of a second rotor 226, also
driven from the cam shaft of the engine.
It will be noted that neither the arrangement of FIG. 5 nor the
arrangement of FIG. 6 requires any contacts for developing the
triggering signals, other than those which may already be present
in the ignition system. The arrangement of FIG. 5 is particularly
advantageous in that it requires comparatively simple and
inexpensive circuit connections to the ignition system. The
arrangement of FIG. 6 is advantageous in permitting additional
flexibility as to the time of generation of the triggering pulses.
The pick-up units 210 and 224 may be adjustable, with respect to
their angular positions. It will be understood that modifications
and variations may be effected without departing from the spirit
and scope of the novel concepts of this invention.
* * * * *