U.S. patent number 3,575,147 [Application Number 04/798,650] was granted by the patent office on 1971-04-20 for electronic fuel injection system.
This patent grant is currently assigned to Ford Motor Company. Invention is credited to Arthur R. Harris, Robert S. Harrison.
United States Patent |
3,575,147 |
Harrison , et al. |
April 20, 1971 |
ELECTRONIC FUEL INJECTION SYSTEM
Abstract
Electrical signals corresponding to air valve position, the
vacuum signal between the air valve and the throttle blade, and the
intake manifold pressure determine the width of pulses applied to
electrical fuel injectors located in the intake manifold. Pulse
frequency is determined by an electrical signal generated by engine
revolution. Electronic circuitry shortens the basic pulse width as
a function of pulse frequency so fuel delivery is determined only
by the above electrical signals.
Inventors: |
Harrison; Robert S. (Detroit,
MI), Harris; Arthur R. (Detroit, MI) |
Assignee: |
Ford Motor Company (Dearborn,
MI)
|
Family
ID: |
25173923 |
Appl.
No.: |
04/798,650 |
Filed: |
February 12, 1969 |
Current U.S.
Class: |
123/483; 123/493;
123/494 |
Current CPC
Class: |
F02D
41/18 (20130101); F02D 41/182 (20130101) |
Current International
Class: |
F02D
41/18 (20060101); F02m 051/00 () |
Field of
Search: |
;123/32 (E)/ ;123/32
(E-1)/ ;123/119,179 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Claims
We claim:
1. In a fuel injection system for a reciprocating internal
combustion engine having at least one electrically operated fuel
injector for delivering fuel to a combustion chamber, an air
passage for delivering air to said combustion chamber, and a
throttle blade in said air passage for controlling the amount of
airflow through the air passage, an electronic fuel control system
comprising:
an air valve in said air passage upstream of said throttle blade,
said air valve being positioned by mass airflow through the passage
so air valve position represents the mass of air flowing through
the passage,
an electrical device attached to said air valve for converting the
air valve position into an electrical signal representative of the
mass airflow through the passage,
an air valve depression sensing device connected to the air passage
between the air valve and the throttle blade for sensing the
pressure therein,
an electrical device connected to the air valve depression device
for converting the pressure into an electrical signal
representative of the air valve depression, and
electronic means connected to said electrical devices and said
injector for controlling the amount of fuel delivered by each
operation of the injector as a function of said electrical
signals.
2. The fuel injection system or claim 1 in which the electronic
means comprises:
pulse generating means for producing a pulse representative of
engine rotation, and
pulse forming means for changing the pulse shape according to said
electrical signal generated by the air valve position, said pulses
being applied to said fuel injector to open and close the
injector.
3. The fuel injection system of claim 2 in which the pulse forming
means comprises:
a power supply circuit coupled to said pulse generating means, said
power supply circuit producing an output voltage inversely
proportional to the frequency of the pulses, and
a pulse shaping circuit coupled to the pulse generating means, the
power supply circuit and the electrical means attached to the air
valve, said pulse shaping circuit producing a pulse having its
width proportional to the output voltage of the power supply
circuit and the electrical signal of said electrical means.
4. The fuel injection system of claim 3 comprising a manifold
pressure sensing device connected to the air passage downstream of
the throttle blade for sensing the pressure therein, and an
electrical device connected to said manifold pressure sensing
device for converting said pressure into an electrical signal
representative of manifold pressure, said electrical signal
representative of manifold pressure being coupled to said pulse
shaping circuit to modify the width of the pulses produced
thereby.
5. The fuel injection system of claim 4 in which the air valve
depression sensing device also is connected to the air passage
downstream of the throttle blade and the electrical signal of said
air valve depression sensing device is representative of a
predetermined blend of manifold pressure and air valve
depression.
6. The fuel injection system of claim 5 in which said electrical
devices are variable resistors and the resistance generated by the
variable resistor connected to the air valve depression sensing
device is coupled in series with the resistance generated by the
variable resistor connected to the manifold pressure sensing
device.
7. The fuel injection system of claim 6 comprising an electrical
resistor means, and a switch means for switching said resistor
means into and out of connection with said electrical device
attached to said air valve, and temperature responsive means for
actuating said switch means, said resistor means being connected to
said electrical device at low temperatures to increase the amount
of fuel delivered by said injector.
8. The fuel injection system of claim 1 comprising a manifold
pressure sensing device connected to the air passage downstream of
the throttle blade for sensing the pressure therein, and an
electrical device connected to said manifold pressure sensing
device for converting said pressure into an electrical signal
representative of manifold pressure, said electrical signal
representative of manifold pressure being coupled to said
electronic means to modify the amount of fuel delivered according
to the manifold pressure.
9. The fuel injection system of claim 8 in which the electrical
signal generated by the low manifold pressure representative of
engine deceleration reduces the amount of fuel delivered by each
operation of the injector.
10. The fuel injection system of claim 1 in which said electrical
devices are variable resistors.
11. The fuel injection system of claim 1 comprising an electrical
resistor means, and a switch means for switching said resistor
means into and out of connection with said electrical device
attached to said air valve, and temperature responsive means being
connected to said electrical device at low temperatures to increase
the amount of fuel delivered by said injector.
12. A fuel metering system for an internal combustion engine
comprising an air passage for delivering air to said engine, said
air passage containing an air valve positioned by the mass of air
flowing through said passage and a manually operable throttle
valve, said throttle valve being located downstream of the air
valve, an electrical device attached to said air valve for
converting the air valve position into a first electrical signal,
vacuum motor means communicating with said air passage downstream
of said throttle blade, said vacuum motor means being responsive to
the intake manifold pressure of said engine, an electrical device
attached to said vacuum motor means for converting the intake
manifold pressure into a second electrical signal, the electronic
means for controlling the amount of fuel metered to said engine as
a function of said first and second electrical signals, said
electronic means including a circuit for producing pulses at a
frequency proportional to engine revolutionary speed and a circuit
for shortening the duration of said pulses as a function of pulse
frequency so the time integrated pulse area is independent of
engine revolutionary speed, said electronic means changing pulse
area according to said first and second electrical signals.
13. The fuel metering system of claim 12 comprising a second vacuum
motor means communicating with said air passage between said air
valve and said throttle valve, and an electrical device attached to
said second vacuum motor means for producing a third electrical
signal, said electronic means controlling the amount of fuel
metered to said engine as a function of said three electrical
signals.
14. The fuel metering system of claim 13 in which the electrical
devices are variable resistors.
15. The fuel metering system of claim 14 comprising passage means
connecting said second vacuum motor means with the air passage
downstream of the throttle valve, and manually positionable control
means in said passage means for adjusting the proportion of the
vacuum signal passing through said passage means to said second
vacuum motor.
Description
SUMMARY OF THE INVENTION
Current electronic injection systems for reciprocating internal
combustion engines use electrical pulses generated by engine
rotation to actuate fuel injectors supplying fuel to the combustion
chambers. An electrical signal generated by engine intake manifold
pressure modifies the duration of the pluses and thereby attempts
to relate the amount of fuel supplied to the engine to engine
requirements. Additional signals responsive to engine temperature,
ambient air temperature, barometric pressure, and air humidity
usually are necessary in such systems to further modify pulse
duration according to actual engine requirements during the many
different phases sand climatic conditions encountered in normal
engine operation. Although these electronic systems are capable of
improving fuel metering, the large number of signals necessary to
sense the quantity of inducted air under the wide variety of
climatic and operational conditions has increased the expense of
the systems to an almost prohibitive level. Commercial versions of
the systems therefore compromised many of these factors to achieve
reasonable cost levels.
This invention utilizes electrical signals generated by the
position of an air valve, the pressure signal between the air valve
and a manually controlled throttle blade, and the intake manifold
pressure to determine the amount of fuel supplied to an engine.
These three sensing points produce signals proportional to the
airmass flowing to the engine combustion chambers for all engine
operating and climatic conditions and thus obviate the need for any
additional signals. In the invention, an electrically actuated fuel
injector is positioned where it will deliver fuel to combustion
chambers of a reciprocating internal combustion engine. An air
passage for delivering air to the combustion chamber contains a
manually operated throttle blade for controlling the amount of
airflow. Air flowing through the air passage positions an air valve
located upstream of the throttle blade. Electrical elements are
attached to the air valve, to a pressure sensitive device connected
to the air passage between the air valve and the throttle blade and
to a pressure sensitive device connected to the air passage
downstream of the throttle blade. An electronic circuit produces
pulses at a frequency determined by engine revolutions and shortens
the pulse duration as a function of pulse frequency so the time
integrated pulse area is independent of engine speed. The circuit
then uses signals from the electrical elements to modify the basic
pulse width according to the engine fuel requirements. These
modified pulses are applied to the fuel injector which opens to
deliver fuel to the engine combustion chamber during each
pulse.
Fuel is supplied to the injectors at a pressure independent of
engine speed. The injectors preferably are located in the engine
intake manifold just upstream of the intake valves and are pulsed
just prior to or during the intake valve opening operation. In
multicylinder engines having the injectors located in the intake
manifold, the injectors can be pulsed individually, in pairs, in
sets of any higher number, or all at the same time. A streamlined
air intake structure is used in the system to provide a low profile
induction system and convenient pressure tapping points. Pressure
signals from two of the above locations are combined in an idle
mixture adjustment system to provide proper pulse widths during
idling conditions.
Variable resistors serve conveniently as the electrical elements.
One side of the resistance is connected to the ground terminal of a
source of electrical energy, and the sensing element is connected
by an electrically insulating material to the movable tap. The
electronic circuit is connected electrically to the movable taps in
a manner such that the final pulse width increases as the
resistance between the taps and ground increases. With a constant
injection pressure, fuel delivery from the injector depends on
pulse area, and the resistances in the electrical elements are
designed to produce the desired pulse width for each set of
operating conditions. Variable capacitance inductance, or other
electrical parameters can be used in place of the variable
resistances to provide the necessary modulation of pulse width.
Cold starting enrichment is provided by a switch connected to a
thermally positioned choke plate located upstream of the air valve.
One switch terminal is connected to ground and the switch pole
contacts that terminal when choke plate is closed to increase the
resistance to ground according to an enriching resistance in series
with the switch. A thermally variable enriching resistance provides
extremely accurate control during cold starting, and even a
constant enriching resistance greatly improves fuel economy and
exhaust emission.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation view of the air intake structure of this
invention showing the external air valve linkage and the linkage
connecting a temperature responsive means to the choke blade and
throttle blade fast idle cam.
FIG. 2 is a schematic of the system showing a sectioned elevation
of the air intake structure and the input circuits of the
electronic controller.
FIG. 3 is a top view of the air intake structure with portions
broken away to shown the idle adjustment system. The external
linkage shown in FIG. 1 has been removed from FIG. 3 for
clarity.
FIG. 4 is a schematic of the electronic circuitry of
controller.
DETAILED DESCRIPTION
Referring to FIGS. 1, 2 and 3, the air intake structure is
indicated generally by numeral 10 and comprises a flange 12
fastened to a corresponding flange on the engine intake manifold
(not shown). An oval conduit 14 made integrally with flange 12
contains an oval air passage 16 that makes a 90.degree. turn and
connects with two circular air passages 18 and 20 located
side-by-side in flange 12. Air passages 18 and 20 communicate with
the air passage in the engine intake manifold.
Extending laterally through air passages 18 and 20 is a throttle
shaft 22. Throttle plates 24 and 26 are mounted on shaft 22 within
circular passages 18 and 20 respectively so clockwise rotation of
shaft 22 open passages 18 and 20.
An air valve shaft 28 extends through air passage 16 and has its
ends mounted rotatably in the conduit 14. Shaft 28 is parallel to
and is mounted slightly above the major diameter of air passage 16.
An air valve plate 30 is fastened to shaft 28 within air passage 16
so opening movement of the air valve rotates shaft 28 clockwise.
Upstream of air valve shaft 28, a choke plate shaft 32 extends
through passage 16. Shaft 32 is parallel to shaft 28 but is mounted
slightly below the major diameter of air passage 16. A choke plate
34 is fastened to shaft 32 within air passage 16.
Referring primarily to FIG. 1, an L-shaped lever 36 is fastened to
shaft 22 outside of flange 12. One leg of lever 36 carries a
projecting table 38. A screw 40 is threaded into a boss 42 mounted
on the exterior of conduit 14 with the end of screw 40 contacting
tab 38 when the throttle blades are in the closed or idling
position.
The other leg of lever 36 terminates near the stepped surface 44 of
a cam member 46 pivotally mounted on conduit 14. A rod 48 connects
cam member 46 with a lever 50 fastened to choke plate shaft 32.
Another lever 52 is fastened to choke plate shaft 32 and is
connected by a rod 54 to a conventional automatic choke mechanism
containing both temperature and manifold pressure responsive
devices. An example of such a choke mechanism is disclosed in U.S.
Pat. No. 3,281,130.
A bellcrank 56 is fastened to air valve shaft 28 and has one leg
connected by a rod 58 to a damping mechanism indicated generally by
numeral 60. A typical damping mechanism is disclosed in U.S. Pat.
application Braun et al., Ser. No. 611,906, filed Jan. 26, 1967,
the entire disclosure of which is hereby incorporated into this
specification. The other leg of bellcrank 56 is connected by a
tension spring 62 to an anchor 64 formed on the exterior of conduit
14. Spring 62 acts though bellcrank 56 to urge air valve plate 30
into its closed position.
A passage 66 is drilled into the left side of flange 12 to
communicate with passage 18 below the closed position of throttle
blade 24. Pressed into the outer end of passage 66 is a tube 68
that connects passage 66 with one chamber 70 of a manifold vacuum
motor 72. Motor 72 contains a flexible diaphragm 74 that separates
chamber 70 from a chamber 76. A compressive spring 78 located in
chamber 70 urges diaphragm 74 into chamber 76.
Projecting through chamber 76 and out of the left side of motor 72
is an actuating rod 80 made of an electrically insulating material.
Rod 80 is connected to the movable tap 82 of a variable resistor
represented by numeral 84. One terminal of the resistor element 86
of variable resistor 84 is floating and the other terminal is
connected to a lead 87, With atmospheric pressure in passage 66,
diaphragm 72 positions tap 82 near the floating terminal of element
86; decreases in the intake manifold pressure move tap 82 toward
the terminal connected to lead 87.
Beneath conduit 14, a second passage 90 is drilled into flange 12
at the midpoint of the flange. Passage 90 intersects a passage 92
drilled into flange 12 from the side, and a short vertical passage
94 connects the intersection point of passages 90 and 92 with air
passage 16 between throttle plate 24 and air valve plate 30.
Passage 94 has a small metering jet 96 pressed into its passage 16
end. A small sensing passage 98 connects passage 92 with passage 18
just below the idling position of throttle blade 24, and a threaded
adjusting screw 100 is threaded into the open end of passage 92 so
its tapered point 102 is movable through the intersection point of
passages 92 and 98.
Referring primarily to FIG. 2, the open end of passage 90 has a
tube 104 pressed therein. Tube 104 connects passage 90 with one
chamber 106 of an air valve depression vacuum motor 108. A
diaphragm 110 separates chamber 106 from a chamber 112 and a
compression spring 114 positioned in chamber 106 urges the
diaphragm 110 toward chamber 112. A rod 116 made of an electrically
insulating material is fastened to diaphragm 110 and projects
through chamber 112 and out of the vacuum motor housing where rod
116 is connected to the movable tap 118 of a variable resistor 120.
Tap 118 is connected to lead 87. One terminal of the resistor
element 122 of resistor 120 is connected to ground and the other
terminal is floating. With atmospheric pressure in passage 90,
diaphragm 110 positions tap 118 near the grounded terminal of
element 122; decreases in the pressure move tap 118 toward the
floating terminal. Chambers 76 and 112 are connected by a tube 125
to a balance port 126 opening into passage 16 upstream of choke
plate 34. Port 126 faces upstream so an impact pressure is
developed at high speeds.
Air valve shaft 28 is connected to the movable tap 128 of a
variable resistor 130. One terminal of the resistor element 131 of
resistor 130 is floating and the other terminal 133 is connected to
a switch arm 134. When air valve plate 30 is closed, tap 128 is
positioned near terminal 133; opening movement of the plate moves
the tap toward the floating terminal of element 131. Choke plate
shaft 32 is connected by an electrically insulating material to
switch arm 134 that moves to contact either of two terminals 135
and 136. Terminal 135 is connected to ground through a resistor 137
and terminal 136 is connected directly to ground. Arm 134 contacts
terminal 135 when the choke plate is closed and contacts terminal
136 when the choke plate moves away from its closed position.
An electrical lead 138 connects tap 82 to one input terminal 140 of
an electronic control indicated in FIG. 2 by numeral 142.
Similarly, a lead 148 connects tap 128 to an input terminal 150. A
third input terminal 152 for control 142 is connected to any device
154 capable of producing a signal having a frequency representative
of engine r.p.m. The output terminal 156 of circuit 142 is
connected via an amplifier (not shown) to the electrical operating
mechanisms of a plurality of fuel injectors 158.
The electronic circuitry shown in FIG. 4 consists of a monostable
multivibrator capable of producing a square wave having a constant
width enclosed by dashed line 160, a power supply capable of
producing an output voltage inversely proportional to the frequency
of the square wave enclosed by dashed line 162, and a monostable
multivibrator capable of producing a variable pulse width enclosed
by dashed line 164. A conventional automotive storage battery 166
has its negative plate connected to ground at 168 and its positive
plate connected through a resistor 170 to a terminal 172. A Zener
diode 174 has its anode connected to the negative battery plate and
its cathode connected to terminal 172. Diode 174 insures a constant
voltage at terminal 172 despite variations in the voltage provided
by battery 166.
Referring to multivibrator 160, terminal 152 is connected through a
capacitor 174 to the base of a PNP type transistor 180. Terminal
172 is connected through a resistor 182 to the emitter of
transistor 180 and through a resistor 184 to the base of transistor
180. A resistor 186 connects the base of transistor 180 to ground
and a resistor 188 connects the collector to ground.
The emitter of transistor 180 is connected to the emitter of a
second PNP type transistor 190. A capacitor 192 couples the
collector of transistor 180 to the base of transistor 190.
Resistors 194 and 196 connect the base and collector of transistor
190 to ground.
Resistors 182, 184, 186, 188, 194 and 196 are selected to reverse
bias transistor 180 and forward bias transistor 190 into saturation
in the absence of a signal at terminal 152. A negative pulse at
terminal 152 is applied to the base of transistor 180 to drive
transistor 180 into its active region. Capacitor 192 couples the
rising voltage at the collector of transistor 180 to the base of
transistor 190, thereby reverse biasing transistor 190. Transistor
190 remains reversed biased until the charge on the right plate of
capacitor 192 discharges through resistor 194 at which point
transistor 190 again switches into conduction. The increased
current through resistor 182 drops the voltage at the emitter of
transistor 180 to begin turning transistor 180 off. Voltage on the
left plate of capacitor 192 then drops to bias transistor 190
rapidly into saturation. With a constant supply voltage, the off
time of transistor 190 depends on the RC constant of capacitor 192
and resistor 194, so each negative pulse at terminal 152 thus
produces a negative going square wave pulse at the collector of
transistor 190 that has a constant pulse width.
Turning to the variable voltage power supply circuit 162, terminal
172 is connected to the collector of an NPN type transistor 202. A
resistor 200 connects the collector to the base of transistor 202.
The base of transistor 202 is connected through a resistor 204 to
ground, and the emitter is connected to the emitter of a PNP type
transistor 206. A resistor 208 connects the collector of transistor
206 to the base of transistor 202.
A resistor 210 connects the emitter of transistor 202 to a terminal
212. Resistor 214 connects terminal 212 to the base of transistor
206, and a resistor 216 in parallel with a capacitor 218 connect
terminal 212 to ground. A resistor 221 connects the collector of
transistor 190 to terminal 212.
Transistors 202 and 206 are biased as linear amplifiers. Resistor
216 and capacitor 218 integrate the square wave from the collector
of transistor 190 into a constant voltage inversely proportional to
the pulse frequency. Resistor 214 applies the constant voltage to
the base of transistor 206 to increase the conduction of transistor
206 in inverse proportion to the voltage. Increased conduction of
transistor 206 increases the voltage at the base of transistor 202
to reduce the conduction of transistor 202. A constant voltage
inversely proportional to the pulse frequency thus appears at the
emitter of transistor 202.
Turning now to multivibrator circuit 164, a resistor 222 connects
the emitter of transistor 202 to the emitter of a PNP type
transistor 224. A resistor 226 connects the emitter of transistor
202 to the base of transistor 224 and respective resistors 228 and
230 connect the base and collector of transistor 224 to ground.
The emitter of transistor 224 is connected by a resistor 231 to the
emitter of a second PNP type transistor 232 that has its collector
connected to ground. Output terminal 156 is connected to the
emitter of transistor 232. A capacitor 236 couples the collector of
transistor 224 to the base of the transistor 232. Terminals 140 and
150 are connected to the base of the transistor 232.
Multivibrator circuit 164 operates in essentially the same manner
as multivibrator circuit 160 except that (1) the square wave
appearing at terminal 156 has positive going pulses rather than
negative and (2) the width of the pulses increases with the
resistances of the variable resistances connected to terminals 140
and 150 but decreases with the voltage appearing at the emitter of
transistor 202. These results occur in the following manner.
Transistor 224 normally is turned off and transistor 232 normally
is conducting, During conduction of transistor 232, a relatively
low voltage appears at terminal 156. Each negative pulse at
terminal 152 is applied to the base of transistor 224 and turns on
that transistor. Capacitor 236 transmits the positive pulse then
appearing at the collector of transistor 224 to the base of
transistor 232 to reverse bias transistor 232. Transistor 232
remains reverse biased until the charge on capacitor 236 is
dissipated through the resistances connected to terminals 140 and
150 to value that is a function of the voltage applied to the
emitter of transistor 232. That voltage in turn is a function of
the voltage at the emitter of transistor 202 which is inversely
proportional to the pulse frequency. By proper selection of
components, the voltage decreases at the emitter of transistor 202
cancel the effects of the frequency increases so the pulse width
appearing at terminal 156 represents only the values of the
resistors connected to terminals 140 and 150.
During engine cranking, choke plate 34 is closed by the automatic
choke mechanism connected to rod 54. Switch arm 134 contacts
terminal 135 to couple resistor 137 between tap 128 and ground.
Cranking produces a slight decrease in intake manifold pressure
that opens air valve 30 slightly. A relatively high resistance thus
appears between terminal 150 and ground to widen the pulses applied
to injectors 158. The high manifold pressure acts via vacuum motor
72 to position tap 82 near the floating end of resistor 86. A
pressure intermediate the manifold pressure and the atmosphere is
sensed by vacuum motor 108 that positions tap 118 at an
intermediate location on resistor 122. Virtually all of resistor 86
and part of resistor 122 thus are in series with tap 82, and this
high resistance also widens the pulse width.
When the engine starts, passage 66 applies the decreased manifold
pressure to diaphragm 74, which moves tap 82 toward the lead 87 end
of resistance 86. At the same time choke plate 34 is pulled open by
the automatic choke mechanism, which switches arm 134 to terminal
136. The resulting decreased resistances eliminate the cold
starting enrichment. Passage 104 applies the low manifold pressure
to diaphragm 110 of vacuum motor 108 so diaphragm 110 moves tap 118
a short distance away from the grounded terminal of element 122.
This increased resistance appearing at terminal 140 produces a rich
mixture for cold engine idling and operation. Threaded screw 100 is
adjusted to determine the portion of intake manifold pressure
applied to vacuum motor 108, which thereby determines the proper
amount of idling fuel. Throttle plate 24 is opened slightly by fast
idle cam member 46 according to the setting of the temperature
responsive choke mechanism.
As the engine warms up during continued operation, choke plate 34
opens slowly. This opening decreases the vacuum signal sensed by
vacuum motor 108 which moves tap 118 to a lower resistance point
that leans the fuel-air mixture accordingly.
During engine road load operation, air valve 30 is positioned by
the mass of air flowing through air passage 16 so a relatively
constant pressure exists in passage 16 between the air valve and
the throttle blade. The opening movement increases the resistance
between tap 128 and ground and thereby increases the width of the
pulses appearing at terminal 156. When high power is demanded from
the engine, the increased intake manifold pressure is applied to
diaphragm 74 and moves tap 82 into a high resistance position that
increases the pulse width accordingly.
Frictional forces associated with the air valve may produce some
hysteresis in response of the air valve to mass airflow. Such
hysteresis produces variations in the pressure between the air
valve and the throttle blade, which are compensated by vacuum motor
108. Vacuum motor 72 and variable resistor 84 are adjusted so the
low intake manifold pressure occurring during engine deceleration
moves tap 82 to the lead 87 side of resistor element 86. Lead 138
then has a reduced resistance to ground which prevents transistor
180 from switching to its nonconducting state. No fuel reaches the
engine combustion chambers under these conditions, which eliminates
undesirable components from the engine exhaust.
Resistor elements 131 can be connected in series with resistor
elements 86 and 122 if desired. Variable resistors can be included
in leads 138 and 148 to provide desired adjustment. A temperature
sensitive variable resistance can be used as resistance 137 to
proportion the amount of cold starting fuel to provide to provide
excellent cold starting characteristics. The system can be modified
so pulse width varies as a function of one electrical signal and
pulse height as a function of the others. Fuel injectors then are
designed to deliver fuel in response to pulse width and height.
Alternatively, pulse width can be decreased with engine speed to
compensate for the increased pulse frequency, and fuel metering can
be determined by pulse height only.
Thus this invention provides an electronic fuel injection system
that uses an air valve to sense the mass of air being inducted into
the engine and determine the width of pulses applied to fuel
injectors. Vacuum motors sensitive to pressure signals in the
intake manifold and in the air induction passage between the air
valve and throttle blade adjust fuel delivery for idling and
maximum power, and cutoff fuel delivery during deceleration to
improve exhaust emission control Injector pulses are synchronized
with engine revolutions and electronic circuitry removes the effect
of increasing pulse frequency on fuel delivery so fuel delivery is
determined only by climate and engine operating parameters.
* * * * *