U.S. patent number 3,794,003 [Application Number 05/217,569] was granted by the patent office on 1974-02-26 for pressure dependent deceleration cutoff for an internal combustion engine fuel delivery system.
This patent grant is currently assigned to The Bendix Corporation. Invention is credited to Junuthula N. Reddy.
United States Patent |
3,794,003 |
Reddy |
February 26, 1974 |
PRESSURE DEPENDENT DECELERATION CUTOFF FOR AN INTERNAL COMBUSTION
ENGINE FUEL DELIVERY SYSTEM
Abstract
This invention relates to an electronic deceleration control,
responsive to engine operating condition sensors, cooperating with
an electronic fuel control computer for an internal combustion
engine for curtailing or terminating the fuel delivery to the
engine under selected engine operating conditions indicating an
operator's demand for deceleration. The deceleration control
restores normal fuel delivery to the engine in response to a second
set of selected engine operating conditions indicating the demand
for deceleration has been terminated. The inventive control
responds to signals indicative of the engine speed and the intake
manifold absolute pressure, and computes the first time derivative
of the intake manifold pressure, giving an immediate indication of
the deceleration demand independent of throttle position or a
minimum manifold pressure. This control system, cooperating with an
electronic fuel injection control system for an internal combustion
engine, substantially reduces the exhaust emissions during the
period of deceleration.
Inventors: |
Reddy; Junuthula N.
(Horseheads, NY) |
Assignee: |
The Bendix Corporation
(Southfield, MI)
|
Family
ID: |
22811609 |
Appl.
No.: |
05/217,569 |
Filed: |
January 13, 1972 |
Current U.S.
Class: |
123/325; 123/493;
261/DIG.19; 123/333 |
Current CPC
Class: |
F02D
41/12 (20130101); Y10S 261/19 (20130101) |
Current International
Class: |
F02D
41/12 (20060101); F02m 051/00 () |
Field of
Search: |
;123/97B,32EA,32AE |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Attorney, Agent or Firm: Flagg; Gerald K. Thompson; William
S.
Claims
What is claimed is:
1. In an internal combustion engine fuel control system having an
intake manifold pressure sensor means operative to generate
pressure dependent signals indicative of engine operating
conditions, a fuel control computer operative to generate a set of
output signals indicative of the engine fuel requirements for each
operational cycle of the engine, and at least one fuel injector
responsive to the signals from said computer operative to control
fuel delivery to the engine, the improvement comprising:
means responsive to just the pressure dependent signals to indicate
a demand for deceleration when the pressure dependent signals are
indicative of a manifold pressure above a first predetermined
pressure and the pressure is decreasing at a rate faster than a
predetermined rate, and to generate an inhibitory signal, said
inhibitory signal communicated to the fuel control computer
controls the operation of said computer and regulates the fuel
delivery to the engine during the deceleration period,
said means further responsive to just the pressure dependent
signals to indicate the end of said demand for deceleration when
the pressure dependent signals are above a second predetermined
pressure and the pressure is decreasing at a rate slower than said
predetermined rate, and to terminate said inhibitory signal to said
computer and restore normal fuel delivery to the engine.
2. The system as claimed in claim 1 wherein said means for
generating said inhibitory signal includes:
first signal generating means responsive to pressure dependent
signals operative to generate a first signal indicative of a
pressure in the intake manifold above said first predetermined
pressure;
second signal generating means responsive to pressure dependent
signals to generate a second signal indicative of a pressure in the
intake manifold above said second predetermined pressure;
a time rate of change detector responsive to the pressure dependent
signals operative to produce a first rate of change signal
indicative that the manifold pressure is decreasing at a rate
faster than said predetermined rate and a second rate of change
signal indicative that the manifold pressure is decreasing at a
rate slower than said predetermined rate; and
a control switch responsive to said first signal from said first
signal generating means and the first rate of change signal from
said time rate of change detector operative to generate said
inhibitory signal, and further responsive to said second signal
from said second signal generating means and said second rate of
change signal from said time rate of change detector operative to
terminate the generation of said inhibitory signal.
3. The system as claimed in claim 2 wherein said first signal
generating means comprises:
a first manifold pressure reference circuit operative to generate a
first reference signal indicative of said first predeterminable
manifold pressure; and
a first comparator circuit responsive to said first reference
signal and said pressure dependent signal from the manifold
pressure sensor operative to produce said first signal when the
manifold pressure is higher than said first predetermined pressure
established by the first manifold reference circuit; and
said second signal generating means comprises:
a second manifold pressure reference circuit operative to generate
a second reference signal indicative of said second predeterminable
manifold pressure; and
a second comparator circuit responsive to said second reference
signal and said pressure dependent signals from the manifold
pressure sensor operative to produce said second signal when the
manifold pressure is higher than said second predeterminable
pressure established by the second mainfold reference circuit.
4. The system as claimed in claim 3 wherein said control switch
comprises:
a set switch operative to produce a signal in response to the
coincidence of signals from the first comparator circuit indicating
a manifold pressure greater than said first predeterminable
manifold pressure and the time rate of change detector indicating
the dynamic pressure in the manifold is decreasing at a rate faster
than said predeterminable rate;
a reset switch operative to produce a signal in response to
coincidence of signals from the second comparator circuit
indicating a manifold pressure greater than said second
predeterminable manifold pressure and the time rate of change
detector indicating the dynamic pressure in the manifold is
decreasing at a rate slower than said predeterminable rate; and
an output switch, switchable from one state to the other in
response to the signals from the set and reset switches, operative
to control the output signal of the said fuel control computer.
5. The system as claimed in claim 4 wherein said time rate of
change detector comprises:
a capacitance;
a first resistance in series with said capacitance;
a second resistance in parallel with said capacitance and said
first resistance, wherein said capacitance, said first resistance
and said second resistance comprises a differentiator, said
differentiator operative to produce a first differentiated signal
when the pressure dependent signal to the differentiator is
indicative of a pressure decreasing at a rate faster than said
predeterminable rate and operative to produce said second
differentiated signal when the pressure dependent signal to the
differentiator is a signal indicative of the manifold pressure
decreasing at a rate slower than said predeterminable rate; and
a switch cooperating with said differentiator responsive to said
first and second differentiated signals operative to produce said
first rate of change signal when the manifold pressure is
decreasing at a rate faster than said predeterminable rate and
operative to produce said second rate of change signal when the
manifold pressure is decreasing at a rate slower than said
predeterminable rate.
6. The system as claimed in claim 5 wherein said first manifold
pressure reference circuit comprises:
a transistor;
a resistance in series with said transistor; and
a voltage divider means connected to said transistor operative to
control a current flow through said transistor, and said series
resistance, said current operative to develop a reference voltage
across said resistance, said reference voltage being an electrical
signal indicative of a manifold pressure greater than the manifold
pressure with the engine operating at curb idle speed; and
said second manifold pressure reference signal circuit
comprises:
a transistor;
a resistance in series with said transistor; and
a voltage divider means connected to said transistor operative to
control a current flow through said transistor and said series
resistance, said current operative to develop a reference voltage
across said resistance, said reference voltage being a signal
indicative of a manifold pressure lower than the manifold pressure
with the engine operating at curb idle speed.
7. The system as claimed in claim 6 wherein said signal generated
by the first manifold pressure reference signal generating circuit
is a signal indicative of a manifold pressure 50 torr greater than
the manifold pressure with the engine operating at said curb idle
speed; and
said signal generated by the second manifold pressure reference
signal generating circuit is a signal indicative of a manifold
pressure 50 torr lower than the manifold pressure with the engine
operating at said curb idle speed.
8. The system as claimed in claim 5 wherein said set and reset
circuits are AND logic gates operative to produce output signals in
response to simultaneous input signals from a plurality of
preceding signal sources.
9. The system as claimed in claim 5 wherein said output switch is a
bistable multivibrator, switchable from one state to the other,
operative in response to a signal from said set switch to generate
an inhibit signal; and
said multivibrator operative to remain in said inhibit signal
generating state until switched to the initial state by a signal
from said reset switch, whereby the fuel delivery to the engine is
terminated during the deceleration period and normal fuel delivery
is restored after the engine operating conditions return to a
normal operating range at the end of the deceleration period.
10. The system as claimed in claim 5 wherein said output switch
comprises:
a bistable multivibrator, switchable from one state to the other,
operative to produce an inhibitory signal in response to a signal
from said set switch and said multivibrator operative to remain in
said signal producing state until switched to its initial state by
a signal from said reset switch; and
a pulse terminating switch responsive to the inhibit signal from
said multivibrator and signals from the fuel control computer,
operative to systematically terminate from each set of fuel
injection signals generated by the fuel control computer, at least
one fuel injection signal, whereby fuel delivery to the engine is
reduced by the intermittent operation of the fuel injector valve in
response to the intermittent signals received from the fuel control
computer during the deceleration period, and to restore normal fuel
delivery to the engine after engine operating conditions return to
the normal state at the end of the deceleration period.
11. The system as claimed in claim 5 wherein said output switch
comprises:
a bistable multivibrator, switchable from one state to the other,
operative to produce an inhibit signal in response to signals from
said set switch and said multivibrator operative to remain in said
signal producing state until switched to its initial state by a
signal from said reset switch; and
a pulse delay circuit, responsive to an inhibit signal from the
multivibrator, signals from the fuel control computer, and signals
from the engine sensors, operative to reduce the length of the fuel
injection signals generated by the fuel control computer, whereby
the fuel delivery to the engine is reduced during the deceleration
period and normal fuel delivery to the engine is restored after the
engine operating conditions return to a normal state of operation
at the end of the deceleration period. 12The system as claimed in
claim 5 wherein said sensor means includes an engine speed sensor
operative to produce a signal indicative of engine speed, said
means for generating an inhibit signal includes:
a speed reference circuit operative to generate an electrical
signal indicative of a predeterminable engine speed;
a speed comparator responsive to signals from said speed reference
circuit and engine speed sensor, operative to generate a signal in
response to the signals from the engine speed sensor indicative of
an engine speed greater than said predeterminable speed established
by the speed reference circuit; and
said set switch further operative to produce a signal in response
to the coincidence of signals from the first comparator circuit
indicating the manifold pressure is greater than said first
reference signal, the speed comparator indicating an engine speed
greater than said predeterminable speed, and the time rate of
change detector indicating the pressure in the manifold is
decreasing at a rate faster than said predeterminable rate.
The system as claimed in claim 12 wherein said speed reference
circuit comprises:
a transistor, a resistance in series with said transistor, and a
voltage divider means connected to said transistor operative to
control a current flow through said transistor and said series
resistance, said current operative to develop a reference voltage
across said resistance, said voltage being a signal indicative of
an engine speed greater than the curb
idle speed of the engine. 14. The system as claimed in claim 12
wherein said speed comparator circuit comprises:
a first transistor means having a pair of states responsive to
signals from the engine speed sensor, operative to be in a first
state during the occurrence of a pulse signal from the engine speed
sensor and operative to be in a second state during the interpulse
period;
a capacitive means responsive to said first transistor means
operative to discharge when said first transistor means is in the
first state, and operative to recharge when said first transistor
means is in the said second state; and
a second switch means having a pair of states responsive to said
capacitance means operative to switch between states when the
potential across said capacitance means during the recharge
interpulse period becomes greater than a preselected value, said
preselected value being
said potential generated by the engine speed reference circuit. 15.
The system as claimed in claim 12 wherein said output switch is a
bistable multivibrator switchable from one state to the other
operative to generate an inhibit signal in response to signals from
said set switch and said multivibrator operative to remain in said
inhibit signal generating state until switched to the initial state
by a signal from said reset switch, whereby the fuel delivery to
the engine is terminated during the deceleration period and normal
fuel delivery is restored after the engine operating parameters
return to a normal operating range at the end of the
deceleration period. 16. The system as claimed in claim 12 wherein
said output switch comprises:
A bistable multivibrator, switchable from one state to the other,
operative in response to a signal from said set switch to produce
an inhibit signal, and said multivibrator operative to remain in
said signal producing state until switched to its initial state by
a signal from said reset switch; and
a pulse terminating switch responsive to the inhibitory signal from
said multivibrator and signals from the fuel control computer
operative to systematically terminate from each set of fuel
injection signals generated by the fuel control computer at least
one fuel injection signal, whereby fuel delivery to the engine is
reduced by the intermittent operation of the fuel injection valves
in response to the intermittent signals from the fuel control
computer during the deceleration period and restore to the engine
after operating parameters return to the normal operating state
at
the end of the deceleration period. 17. The system as claimed in
claim 12 wherein said output switch comprises:
a bistable multivibrator, switchable from one stage to the other,
operative to produce an inhibitory signal in response to a signal
from said set switch and said multivibrator operative to remain in
said signal producing state until switched to its initial state by
a signal from said reset switch; and
a pulse delay circuit responsive to the inhibit signal from the
multivibrator, signals from the fuel control computer, and signals
from the engine sensors operative to reduce the length of the fuel
injection signals generated by the fuel control computer, whereby
fuel delivery to the engine is reduced during the deceleration
period and normal fuel delivery to the engine is restored after the
engine operating parameters return to the normal operating state at
the end of the deceleration
period. 18. A deceleration control operative to control the output
signals from a fuel control computer for an internal combustion
engine having sensor means including a manifold pressure sensor
generating signals indicative of the engine's operating conditions,
comprising:
first signal generating means responsive to pressure dependent
signals operative to generate a first signal when the manifold
pressure is higher than a first predeterminable pressure;
second signal generating means responsive to pressure dependent
signals operative to generate a second signal when the mainfold
pressure is higher than a second predeterminable pressure;
a time rate of change detector responsive to pressure dependent
signals from the manifold pressure sensor operative to produce a
first rate of change signal indicative of a manifold pressure
decreasing at a rate faster than a predeterminable rate and further
operative to produce a second rate of change signal indicative of
the manifold pressure decreasing at a rate slower than said
predeterminable rate;
a control switch responsive to said first signal from said first
signal generating means and said first rate of change signal
generated by said time rate of change detector operative to
generate an inhibitory signal which controls the operation of the
engine fuel control computer and regulates the fuel delivery to the
engine and further responsive to said second signal generated by
said second signal generating means and said second rate of change
signal generated by said time rate of change detector operative to
terminate said inhibitory signal and restore fuel
delivery to the engine. 19. The deceleration control as claimed in
claim 18 wherein said time rate of change detector comprises:
an input differentiator circuit and a switch responsive to the
pressure dependent signals from the manifold pressure sensor
indicative of a changing pressure operative to produce said first
rate of change signal in response to an input signal indicative of
a manifold pressure decreasing at a rate faster than said
predeterminable rate and operative to produce said second rate of
change signal indicative of pressure decreasing at a
rate slower than said predeterminable rate. 20. The deceleration
control as claimed in claim 19 wherein said first signal generating
means comprises:
a first manifold pressure reference circuit operative to generate
on a first reference electrical signal indicative of a first
predeterminable pressure;
a first comparator circuit responsive to signals from said first
manifold pressure reference circuit and the signal from the
manifold pressure sensor operative to produce a signal when the
signal from the manifold pressure sensor is indicative of a
pressure greater than the signal generated by said first manifold
pressure reference circuit; and
wherein said second signal generating means comprises:
a second manifold pressure reference circuit operative to generate
a second reference electrical signal indicative of a second
predeterminable pressure; and
a second comparator circuit, responsive to signals from said second
manifold pressure reference circuit and signals from the manifold
pressure sensor operative to produce a signal when the signal from
the pressure sensor is indicative of a pressure higher than the
signal generated by
said second manifold pressure reference circuit. 21. The
deceleration control as claimed in claim 20 wherein said control
switch comprises:
a set switch operative to produce a signal in response to the
coincidence of signals from said first comparator, indicating a
manifold pressure greater than said first reference signal, and
said first signal from the time rate of change detector, indicating
the pressure in the manifold is decreasing at a rate faster than
said predeterminable rate;
a reset switch operative to produce a signal in response to the
coincidence of signals from the second comparator, indicating a
manifold pressure greater than said second reference signal, and
the time rate of change detector, indicating the pressure in the
manifold is decreasing at a rate slower than said predeterminable
rate; and
an output switch switchable from one state to the other in response
to signals from said set and reset switches operative to generate
said
inhibit signal. 22. The deceleration control as claimed in claim 21
wherein said output switch comprises a bistable multivibrator,
switchable from one state to the other, operative to generate said
inhibit signal in response to a signal from said set switch;
and
said multivibrator operative to remain in said inhibit signal
generating state until switched to its initial state by a signal
from said reset
switch,. 23. The deceleration control as claimed in claim 21
further comprising:
a speed reference circuit operative to generate an electrical
signal indicative of a predeterminable engine speed;
a speed comparator, responsive to signals from said speed reference
circuit and engine speed sensor operative to generate a signal in
response to signals from the engine speed sensor indicative of an
engine speed greater than said predeterminable speed established by
said speed reference circuit; and
said set switch, further operative to produce a signal in response
to the coincidence of signals from said first comparator,
indicating the manifold pressure is greater than said first
reference signal, said speed comparator, indicating an engine speed
greater than said predeterminable speed, and said time rate of
change detector, indicating the pressure in the engine manifold is
decreasing at a rate faster than said
predeterminable rate. 24. The deceleration control as claimed in
claim 23 wherein said output switch comprises:
a bistable multivibrator, switchable from one state to the other,
operative to generate said inhibit signal in response to said
signal from said set switch and said multivibrator operative to
remain in said inhibit signal generating state until switched to
the initial state by a signal from said
reset switch. 25. A deceleration control operative to control the
output signals from a fuel control computer for an internal
combustion engine having sensor means generating signals indicative
of the engine's operating condition, wherein said sensor means
includes at least one sensor generating signal having a static
component indicative of the magnitude of the signal generated by
said at least one sensor at any given time, and one dynamic
component indicative of the rate of change of the signal generated
by the at least one sensor as a function of time, comprising:
means responsive to the static component of the signal from just
one of said at least one sensor for generating condition signals
indicative of at least one predetermined engine operating
condition;
means responsive to the dynamic component of the signal from the
same just one of said at least one sensor for generating rate of
change signals indicative of at least two different rates of change
in the operating conditions of the engine, a first rate of change
signal indicative of the presence of a deceleration condition, and
a second rate of change signal indicative of the absence of said
deceleration condition; and
means responsive to said condition signals and said first rate of
change signal for determining a demand for deceleration and for
generating an inhibitory signal controlling the operation of the
fuel control computer to curtail fuel delivery to the engine during
the period of deceleration, and further responsive to said
condition signal and said second rate of change signal for
determining the end of said demand for deceleration and
terminating said inhibitory signal. 26. The deceleration control of
claim 25 wherein said means for generating condition signals
generates two condition signals indicative of two different engine
operating conditions, a first condition signal determinative that
the engine operating conditions are such that fuel delivery to the
engine should be curtailed during deceleration and a second
condition signal determinative that the engine's operating
conditions approximate the curb idle operating condition.
Description
BACKGROUND OF THE INVENTION
This invention relates to a deceleration electronic control
responsive to engine operating parameters, and cooperating with an
electronic fuel control system of an internal combustion engine,
for curtailing or terminating fuel delivery to the engine, under
selected engine operating conditions indicative of the operator's
demand for deceleration. More particularly, the invention relates
to an electronic control, wherein the fuel delivery to the engine
is curtailed or terminated when the operator has demanded
deceleration by manually changing the position of the intake
manifold throttle valve, reducing the air flow to the engine,
causing the intake manifold pressure to decrease. Unless the fuel
delivery is curtailed or terminated at the same time the air
delivery to the engine is reduced, excessive fuel is injected into
the system, providing the engine with an air/fuel mixture incapable
of complete combustion within the engine. This type of operation
wastes fuel and adds to the total exhaust emissions from the
engine. Simple termination of the fuel delivery to the engine
during deceleration eliminates the incomplete combustion problem
and is a satisfactory solution to the emission problem for internal
combustion engines which are not equipped with thermal or catalytic
reactors in the exhaust systems as the final remover of exhaust
pollutants. Automotive emission standards of the future might
require such reactors on all internal combustion engines;
therefore, their operating characteristics must also be considered.
Most of these thermal and catalytic reactors are designed to
operate efficiently at elevated temperature. Terminating fuel
delivery to the engine terminates combustion and the air ejected by
the engine into the exhaust system is relatively cold, tending to
cool the reactors. Cooling the reactors degrades their pollutant
removal efficiency and results in undesirable pollutants being
emitted from the exhaust system of the engine for a finite period
of time after the fuel delivery to the engine has been restored.
Curtailment of fuel delivery during deceleration coupled with an
advance or retardation of the ignition spark would eliminate both
the incomplete combustion problem and the emission of cold air into
the reactors. Just enough fuel needs to be injected into the system
to maintain the temperature of the reactors, while the advance or
retardation of the ignition spark provides for the complete
combustion of the injected fuel without adding power to the engine.
The ignition spark may be advanced or retarded depending upon the
characteristics of the individual type of engine and its ignition
system.
The prior art, as represented in U.S. Letters Patent No. 3,596,640,
issued Aug. 3, 1971, to George V. Bloomfield, and No. 3,612,013,
issued Oct. 12, 1971, to Charles C. Gambill, describe electronic
fuel injection control circuits with provisions for curtailing or
terminating fuel delivery to the engine upon an operator's demand
for deceleration, and restoring said fuel delivery after
predetermined engine operating conditions have been fulfilled. The
prior art shows the use of various means for determining the
operator's demand for deceleration. These means may be used
singularly or in comjunction with the rotational speed of the
engine to determine the operator has requested deceleration.
Several systems use an electrical switch mechanically linked with
the operator's accelerator pedal as an indicator of the operator's
demand for deceleration. Other systems use an electrical switch
activated by a low manifold absolute pressure in conjunction with
the speed of the engine as operating parameters indicative of the
operator's demand for deceleration. The electrical switch
mechanically linked to the accelerator pedal or throttle valve has
the disadvantage that the signal is given only when the pedal or
valve is at or near the curb idle position, i.e., when the operator
has removed all pressure from the accelerator pedal. A deceleration
demand in which the operator has only partially relaxed his
pressure on the accelerator pedal would not be sensed by the
deceleration control circuit. The control circuits which obtain
their signals from the manifold pressure sensors have much the same
disadvantage, because a deceleration demand in which the throttle
valve is partially closed will not always result in a manifold
pressure low enough to trigger the sensor. This system also has a
built-in delay between the time the demand occurs and the time the
signal indicative of the demand is received by the control circuit.
The objective of the present invention is to overcome the
deficiencies of the prior art by providing a deceleration control
circuit for curtailing or terminating the delivery of fuel to the
engine which is immediately responsive to changes in the engine's
operating conditions indicative of the operator's demand for
deceleration, and which restores normal fuel delivery to the engine
in response to a second set of engine operating conditions
indicative of the termination of the deceleration demand. The
deceleration demand may be automatically terminated after the
engine has come to a curb idle speed, and the manifold pressure
stabilizes or the operator manually reopens the throttle valve.
SUMMARY OF THE INVENTION
The invention is a deceleration control cooperating with an
electronic fuel control system of an internal combustion engine for
curtailing or terminating the fuel delivery to the engine when the
engine speed is above a determinable value, the manifold absolute
pressure is above a first determinable value, and the time rate of
change of the manifold pressure becomes negative, indicating the
operator has demanded deceleration, and to restore normal fuel
delivery to the engine after the manifold absolute pressure has
returned above a second determinable value and the time rate of
change of the manifold pressure becomes positive indicating the
operator has terminated the demand for deceleration.
Advantages of the inventive control circuit are immediate response
to the operator's demand for deceleration, response to a
deceleration demand for conditions other than a closed throttle,
and deactivation only after the demand for deceleration has
terminated, which are effective in substantially reducing the
exhaust emissions of an internal combustion engine with electronic
fuel injection. Another advantage is that no new sensors or moving
parts are required by this deceleration control.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic of an Electronic Fuel Control System with the
inventive Deceleration Control.
FIG. 2 is a block diagram of the Deceleration Control.
FIG. 3 is a circuit diagram of the engine speed reference signal
generating circuit and the engine speed comparator.
FIG. 4 is a circuit diagram of a preferred embodiment of the
Deceleration Control.
FIG. 5 is a block diagram of an alternate embodiment of the
Deceleration Control, responsive to signals from the manifold
absolute pressure sensor only.
FIG. 6 is a block diagram of a Fuel Control System, operative to
terminate fuel delivery to the engine in response to signals from
the Deceleration Control.
FIG. 7 is a block diagram of a Fuel Control System operative to
curtail fuel delivery by systematically terminating some of the
fuel injection pulses generated by the Fuel Control Computer during
deceleration.
FIG. 8 is a block diagram of a Fuel Control System operative to
curtail fuel delivery by curtailing the length of the fuel
injection pulses generated by the Fuel Control Computer during
deceleration.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, an internal combustion engine, the electronic
fuel control system, and the deceleration control circuit are shown
in schematic form. The system is comprised of an internal
combustion engine 10 with an input fuel system 11 delivering fuel
to a set of electrically activated fuel injector valves 12 located
on the intake manifold 13. The air flow to the engine 10 is
controlled by the operator's throttle control 14, shown as a foot
pedal, which activates through linkage 16 a valve 15 in the throat
of the air intake manifold 13. The amount the throttle valve 15 is
opened is indicative of the operating speed of the engine under
normal operating conditions. The fuel delivery to the engine 10 is
controlled by the Fuel Control Computer 17 which responds to the
signals from engine sensors indicating engine operating conditions
such as the intake Manifold Absolute Pressure Sensor 18, the Engine
Speed Sensor 19, and others not shown. The Fuel Control Computer 17
computes the correct amount of fuel required for efficient
operation of the engine and produces electrical signals, indicative
of the engine fuel requirements, which activate fuel injector
valves 12. The fuel injector valves inject fuel into the intake
manifold 13 upstream of the engine's intake valves. The inventive
Deceleration Control 20 is an electronic control circuit responsive
to signals of the Manifold Absolute Pressure Sensor 18 and the
Engine Speed Sensor 19 which produces an inhibitory signal
indicative of the operator's demand for deceleration. This
inhibitory signal controls the Fuel Control Computer 17 by changing
its mode of operation so that the signals transmitted to the fuel
injector valves 12 are indicative of this demand for deceleration
and fuel delivery to the engine is curtailed or terminated. The
deceleration control also terminates its inhibitory signal in
response to signals from the engine sensors indicating the demand
for deceleration has ended. Power source 21 provides electrical
power to the Fuel Control Computer 17 and the Deceleration Control
20. The power source 21 may be a battery as shown or may be other
electrical power sources such as the alternator or generator of a
present-day motor vehicle. It will be understood that this
representation is illustrative and other arrangements are known and
utilized. Furthermore, it is well known in the art of electronic
fuel control computers that computer 17 may control one or more
injection valves 12 arranged to be activated singularly or in
groups of varying numbers in a sequential as well as a simultaneous
mode of operation.
FIG. 2 is a block diagram of the Deceleration Control 20. This
control consists of three reference signal circuits generating
electrical signals indicative of the determinable engine operating
parameters. Reference 1, Signal Generating Circuit 22, generates an
electrical signal indicative of the electrical signal generated by
the intake Manifold Absolute Pressure Sensor 18 for a
predeterminable absolute pressure in the manifold. The pressure
which is indicative of the signal generated by Reference 1, Circuit
22, lies between the intake manifold pressure with the engine
operating at curb idle speed and the nominal intake manifold
pressure with the engine operating at cruise speed. For a typical
automotive internal combustion engine the signal generated by the
Reference 1, Circuit 22, would be the nominal intake manifold
pressure at curb idle engine speed plus 50 torr. Reference 2,
Signal Generating Circuit 23, generates an electrical signal
indicative of the electrical signal generated by the intake
Manifold Absolute Pressure Sensor 18 for a predeterminable absolute
pressure which is less than the nominal intake manifold pressure of
the engine operating at curb idle speed. Again, for a typical
automotive internal combustion engine, the signal generated by the
Reference 2, Circuit 23, would be the nominal intake manifold
pressure at curb idle engine speed minus 50 torr. Since the
operating parameters of the various types of internal combustion
engines will vary considerably, the signals generated by the
Reference 1 and 2 circuits will have to be determined for each
individual type of engine.
Reference 3, Signal Generating Circuit 24, is an engine speed
reference circuit and generates an electrical signal indicative of
a predeterminable engine speed which is greater than the curb idle
speed of the engine. The signal from the Reference 3, Circuit 24,
and the Engine Speed Sensor 19 are transmitted to the Engine Speed
Comparator 25 which generates an electrical signal when the signal
received from the Engine Speed Sensor 19 is indicative of an engine
speed faster than the predetermined speed represented by the signal
generated by the Reference 3, Circuit 24. The signal generated by
the Engine Speed Comparator 25 is transmitted to the Set Circuit
26, which is an AND logic circuit with three input gates.
Comparator 1 Circuit 27 receives signals from the Manifold Pressure
Sensor 18 and the Reference 1 Circuit 22 and generates a signal
when the manifold pressure signal is greater than the signal
generated by the Reference 1 Circuit 22. The output signal from
Comparator 1 indicative of a manifold absolute pressure greater
than the predetermined value established by the Reference 1 circuit
is also transmitted to the Set Circuit 26.
Comparator 2 Circuit 28 receives signals from the Manifold Pressure
Sensor 18 and the Reference 2 Signal Generating Circuit 23 and
generates a signal when the manifold absolute pressure signal is
greater than the signal generated by the Reference 2 Circuit 23.
The output signal from the Comparator 2 circuit indicative of a
manifold absolute pressure greater than the predetermined value
established by Reference 2 Circuit 23 is transmitted to the Reset
Circuit 30. The Reset circuit 30 is an AND logic circuit with two
input gates.
The time rate of change (dP/dt) Detector 29 is a differentiating
circuit which detects the time rate of change of the signal from
the Manifold Pressure Sensor 18 and generates two electrical
signals, one indicative of a decreasing pressure in the manifold or
the time rate of change (dP/dt) of the manifold pressure is
negative, and the second signal indicative of when manifold
pressure is increasing or the time rate of change (dP/dt) is
positive. The first signal indicating a decreasing pressure (dP/dt,
negative) is transmitted to the Set Circuit 26, and the second
signal indicating an increasing pressure (dP/dt, positive) is
transmitted to the Reset Circuit 30. When the manifold pressure is
not changing or is increasing or decreasing slowly, the output
signal from the dP/dt Detector 29 is indicative of an increasing
pressure, or dP/dt positive.
The Set Circuit 26 receives signals from the Engine Speed
Comparator 25, Comparator 1 Circuit 27, and the dP/dt Detector 29
and generates an output signal when the engine speed is greater
than the speed determined by the Reference 3 Circuit 24, the
manifold pressure is higher than the pressure determined by the
Reference 1 Circuit 22, and the time rate of change of the manifold
pressure is negative. This signal is transmitted to an Output
Switch 31 where it switches the Output Switch to its set state and
causes the Output Switch to transmit an inhibitory signal to the
Fuel Control Computer 17.
Output Switch 31, which may be a Bistable Multivibrator, is
normally in the reset state controlled by a positive signal from
the time rate of change Detector 29 and the output signal from the
Comparator 2 Circuit 28. Normal engine operating parameters
including curb idle conditions trigger the Reset Circuit 30 which
prevents the Deceleration Control 20 from producing a deceleration
demand signal. It is only when the three conditions are fulfilled,
that is, when the engine speed is higher than a predetermined
value, the manifold absolute pressure is higher than a
predetermined value, and the manifold pressure is decreasing,
indicative of an operator's demand for deceleration, that a signal
is produced by the Set Circuit 26. The signal from the Set Circuit
26 sets the Output Switch 31 in the second state, which generates
an inhibitory signal which is transmitted to the Electronic Fuel
Control Computer 17. The electronic fuel control computer responds
to this signal and curtails or terminates fuel delivery to the
engine as long as the inhibitory signal is present.
FIG. 3 shows the circuit details of the Reference 3 Engine Speed
Reference Circuit 24 and the Engine Speed Comparator 25. The
circuit is shown being energized by voltage supply designated B+,
applying a potential to a common conductor 101. Common conductor
102 is connected to the negative terminal of the voltage supply
which is illustrated as a common ground in FIG. 3. Voltage pulses
from the engine speed sensor 19 indicative of the engine speed are
transmitted to the input terminal 103. This pulse is communicated
to the base of transistor 104 through resistance 105, causing
transistor 104 to conduct for the duration of each pulse received.
When the transistor 104 is in the nonconducting state the signal at
the collector of transistor 104 is high and is approximately equal
to B+, and when the transistor conducts the signal is low and is
approximately equal to ground. Conduction of transistor 104
communicates a low signal to the base of transistor 107 through
resistance 106 causing transistor 107 to conduct. The potential at
the emitter of transistor 107 is determined by the resistive
network consisting of resistances 108, 109, 110, and 111.
Resistances 108 and 109 form the voltage divider network between B+
and ground, transmitting by means of resistance 110 a bias
potential to the base of transistor 112 and one end of the
capacitance 113 in the absence of an input signal at terminal 103.
Resistance 111 communicates this potential to the emitter of
transistor 107. Conduction of transistor 107 provides a relatively
low electrical resistance path from the junction 114 between
resistance 110 and capacitance 113 to ground, discharging
capacitance 113. The capacitance 113 and the resistance 110 form an
RC network with a time constant longer than the intervals between
pulses received from the engine speed sensor 19 with the engine
operating at nominal operating speeds. Therefore, capacitance 113
will not fully recharge between pulses from the speed sensor 19,
causing the potential at junction 114 to be less than the potential
at the junction of the voltage divider network formed by the
resistances 108 and 109. The signal at the junction 114 is
inversely proportional to the speed of the engine. That is, the
signal is high when the engine speed is low and the signal is low
when the engine speed is fast.
Transistor 112 conducts when the potential at its base is higher
than the potential at its emitter by one V.sub.BE. The potential at
the emitter of transistor 112 is determined by the Reference 3
Engine Speed Generating Circuit 24 which is comprised of
resistances 115 and 116, transistor 117 and the resistance 118. A
voltage divider network, resistances 115, and 116, transmits a
signal to the base of transistor 117 causing it to conduct. Current
flowing through the transistor 117 flows through the resistacne 118
causing an intermediate potential to be formed at the junction
between the resistance 118 and the emitter of transistor 117. The
value of the intermediate potential is determined by the values of
the resistances 115, 116, and the conductance of transistor 117.
These values are selected so that, when the engine is operating at
speeds greater than a preselected speed, the potential at the base
of transistor 112 will be lower than the potential at its emitter,
and transistor 112 will be in a nonconducting state.
At low engine speeds, transistor 112 conducts, causing transistor
119 to conduct, transmitting a positive signal to capacitance 120,
charging capacitance 120 to a potential approximately equal to B+.
This positive potential is also transmitted to the base of
transistor 121 through resistance 122, which is in series with the
resistance 123 to ground causing transistor 121 to conduct. When
transistor 121 conducts, the signal at terminal 124, communicating
with the collector of transistor 121, is low, and when transistor
121 is in the nonconducting stage the signal at terminal 124 is
high and is approximately equal to B+. Capacitance 120 and
resistances 122 and 123 form a long time constant RC network which
maintains a positive potential applied to the base of transistor
121 when the current flow through transistor 119 is intermittent
due to the intermittent conduction of transistor 112 in response to
signals from the engine speed sensor 19.
At high engine speeds, transistor 112 is nonconductive, blocking
transistor 119, blocking the current flow to the base of transistor
121. This causes transistor 121 to become nonconductive and the
output signal at terminal 124 is high, approximately equal to
B+.
The operation of the circuit is such that, when the speed of the
engine is above a predetermined level, the output signal from the
Engine Speed Comparator 25 is a positive voltage on terminal 124,
approximately equal to B+. When the speed of the engine is below
the predetermined value, the output signal at terminal 124 is low
and is approximately equal to ground.
FIG. 4 shows the circuit details of the Reference 1 Circuit 22,
Reference 2 Circuit 23, Comparator 1 Circuit 27, Comparator 2
Circuit 28, dP/dt Detector 29, Set Circuit 26, Reset Circuit 30,
and Output Switch 31. These circuits are shown being energized by a
voltage supply designated B+. The negative terminal of the voltage
supply is connected to a common conductor designated as ground.
This voltage supply may readily be the same source of energy
illustrated and described with regard to FIG. 3. A man skilled in
the art will recognize that the electrical polarity of the voltage
supply can be readily reversed. These circuits receive, along with
the voltage supply, input signals from the engine sensors as well
as the output from the Engine Speed Comparator 25. Referring first
to the Reference 1 Signal Generating Circuit 22 and its companion
Comparator 1 Circuit 27, an electrical signal is developed by the
voltage divider network, consisting of resistances 201 and
potentiometer 202 connected between B+ and ground. The signal taken
from the slider arm of the potentiometer is communicated to the
base of transistor 203, causing transistor 203 to conduct.
Transistor 203 in series with resistance 204 forms a voltage
divider which communicates a potential intermediate B+ and ground
to the emitter of transistor 205. The conductance of transistor 203
is adjusted by potentiometer 202 so that the potential developed
across resistance 204 is indicative of a signal from the Manifold
Absolute Pressure Sensor 18 for a predetermined pressure. The
signal from the Manifold Pressure Sensor 18 is communicated to the
Comparator 1 Circuit 27 through terminal 206. Terminal 206
communicates this signal to the base of transistor 205. When the
signal from the Manifold Pressure Sensor 18 is a voltage that is
higher than the voltage developed across the resistance 204,
transistor 205 conducts causing transistor 207 to conduct. Current
flowing through transistors 207 flows through the voltage divider
network consisting of resistances 208 and 209. When transistor 207
conducts, the output signal taken from the junction between
resistances 208 and 209 is a voltage intermediate B+ and ground.
The value of this signal is adjusted by appropriate selection of
the values of resistances 208 and 209 to produce a signal of
sufficient magnitude to activate the Set Circuit 26. When the
signal from the pressure sensor 18 is lower than the voltage
developed across resistance 204, transistor 205 is blocked.
Nonconductance of transistor 205 blocks transistor 207, and the
potential at the junction of resistances 208 and 209 is
approximately equal to ground potential.
The function of the Reference 1 Signal Generating Circuit 22
cooperating with the Comparator 1 Circuit 27 is to generate and
transmit a positive signal to the Set Circuit 26 when the signal
from the Manifold Pressure Sensor 18 is higher than a predetermined
value and to terminate said signal to the Set Circuit 26 when the
signal from the Manifold Pressure Sensor 18 is lower than the
predetermined value.
The Reference 2 Signal Generating Circuit 23 and its companion
comparator, Comparator 2 Circuit 28, are identical to the Reference
1 Signal Generating Circuit 22 and its companion Comparator 1
Circuit 27 discussed above. Therefore, the function of the
component parts and the operation of the circuit need not be
repeated. The output signal of the Comparator 2 Circuit 28 is a
high voltage signal transmitted to the Reset Circuit 30 when the
voltage signal from the Manifold Pressure Sensor 18 is greater than
a predetermined value of the Reference 2 Circuit. This high signal
is terminated when the signal from the Manifold Pressure Sensor 18
is less than the predetermined value of the Reference 2 Circuit
23.
The predetermined reference signal of the Reference 1 and Reference
2 Signal Generating Circuits may be the same, but in the preferred
embodiment the output signal for the Reference 2 Signal Generating
Circuit is indicative of a manifold pressure lower than the
pressure indicated by the signal of the Reference 1 Circuit.
Referring to the Time Rate of Change (dP/dt) Detector 29, the
signal from the Manifold Pressure Sensor 18 is transmitted to
terminal 401. This signal is communicated to the base of transistor
402 through the differentiator network which comprises of
capacitance 403 in series with resistance 404 and resistance 405,
in parallel with capacitance 403 and resistance 404. The
resistances are selected so that a nonfluctuating signal applied to
terminal 401 will cause transistor 402 to conduct. The collector of
transistor 402 is electrically in series with resistor 406 so that
when transistor 402 is nonconductive, the signal at the collector
of transistor 402 is approximately equal to B+, and when transistor
402 conducts the signal at this point is approximately equal to
ground. When transistor 402 conducts, a low signal is communicated
to the Set Circuit 26 and when transistor 402 is blocked a high
signal is communicated to the Set Circuit 26. Conductance of
transistor 402 also causes a low signal to be communicated to the
base of transistor 407 via resistor 408. This causes transistor 407
to block. When transistor 407 blocks, the signal at the collector
of transistor 407 is high. This signal is communicated to a gate of
the Reset Circuit 30. When transistor 402 blocks a high signal is
transmitted to the base of transistor 407, causing transistor 407
to conduct. This causes the signal at the collector of transistor
407 to become low, terminating the high signal being communicated
to the Reset Circuit 30.
The differentiator network which comprises capacitance 403 in
series with resistance 404 and resistance 405 in parallel with
capacitance 403 and resistance 404 is operable to block transistor
402 when the time rate of change (dP/dt) of the signal from the
pressure sensor 18 is negative. The value of capacitance 403 and
resistances 404 and 405 are selected so that the time rate of
change of a decreasing input signal from the pressure sensor must
exceed a predeterminable rate before it can cause transistor 402 to
block. A positive time rate of increase in the signal at terminal
401 is immediately communicated to transistor 402 through
capacitance 403 and resistance 404, increasing the conductance of
transistor 402 causing no change in the signals transmitted to the
Set and Reset Circuits 26 and 30. After a period of time
approximately equal to a time constant of the RC network, the
potential at the base of transistor 402 returns to its initial
value of approximately one diode drop above ground. A negative time
rate of change signal from the pressure sensor 18 indicative of a
decreasing manifold pressure causes a decreasing potential to be
communicated to the base of transistor 402. causing it to block
when the rate of decrease exceeds the time constant of the
differentiator and reverses the signal communicated to the Set and
Reset Circuits 26 and 30, respectively. The signals remain in this
state as long as the negative time rate of change signal holds
transistor 402 blocked. When time rate of change is less than a
predetermined rate, or positive, the circuit reverts to its normal
state.
The function of Time Rate of Change Detector 29 is to generate and
communicate a positive voltage signal to the Set Circuit 26 when
the manifold absolute pressure is decreasing (dP/dt negative) at a
rate greater than a predetermined value to terminate said signal
when the manifold absolute pressure is increasing or is relatively
stable, and to generate and communicate a positive voltage signal
to the Reset Circuit 30 when the manifold absolute pressure is
increasing.
The Set Circuit 26 is an AND logic gate which responds to signals
from the Engine Speed Comparator 25, the Comparator 1 Circuit 27
and the Time Rate of Change Detector 29. The signal from the Engine
Speed Comparator 25 is communicated to terminal 124. When the
engine speed is less than the predetermined value, the signal at
124 is approximately equal to ground. This low signal is
transmitted to one end of the resistance 501 through a gate diode
502, causing the potential at the junction 507 between diode 502
and the resistance 501 to be approximately two diode drops above
ground. When the engine speed is greater than the predetermined
value, a positive signal appears at terminal 124. However, this
signal is blocked by diode 502; therefore, a positive signal at
diode 502 has no influence on the potential at junction 507. In a
similar manner, when the manifold pressure is less than the
predetermined value of the Comparator 1 Circuit 27, the output
signal is a low resistance to ground. This signal is communicated
to junction 507 through diode 503, and the potential at junction
507 is approximately equal to ground. When the manifold pressure is
higher than the predetermined value of Comparator 1 Circuit 27, the
output is a positive voltage which is blocked by the diode 503 and
has no effect on the potential at junction 507. The signal from
Detector 29 to the Set Circuit 26 is low or a ground signal when
the time rate of change of the manifold pressure is zero, or
positive. This signal is communicated to junction 507 through diode
504, causing junction 507 to have a potential approximately equal
to ground. The signal from Detector 29 is a positive voltage when
the manifold pressure is decreasing. This signal is blocked by
diode 504 and also has no influence on the potential at junction
507. In the absence of a ground or low signal at any one of the
input gates, diodes 502, 503, and 504, current flows from B+
through resistance 501 through diode 505 and diode 506 to the base
of transistor 601 in the Output Switch 31 shown as a bistable
multivibrator. This current flow causes transistor 601 to conduct,
which ultimately results in a high output signal from the
multivibrator circuit. A low or ground signal at any one of the
input diodes provides a low resistance path from junction 507 to
ground, which is operable to terminate the current flow to the base
of transistor 601. Termination of the current flow to the base of
transistor 601 terminates the set signal to the bistable
multivibrator, which will remain in the set state until it receives
a reset signal.
The function of the set circuit 26 is to provide a signal to the
Output Switch 31, causing the switch to produce an inhibitory
signal when the Set Circuit 26 receives signals indicating the
engine speed is above a predetermined value, the manifold pressure
is above a predetermined value, and the manifold pressure is
decreasing. The set signal to the switch 31 will only occur if
simultaneous high signals are received at the three input gates,
diodes 502, 503, and 504 of the Set Circuit 26.
The set signal transmitted from Set Circuit 26 to the Output Switch
31 illustrated as a bistable multivibrator in FIG. 4 causes
transistor 601 to conduct. The conductance of transistor 601 causes
a low signal to be communicated to transistor 602 by means of
resistance 603. A low signal at the base of transistor 602 turns
transistor 602 off, and communicates a high signal approximately
equal to B+ to output terminal 604. This high signal is also
communicated to the base of transistor 601 by resistance 605 which
latches the bistable multivibrator in this state independent of the
signal received from the Set Circuit 26 until a high signal is
received at the base of transistor 602 from the Reset Circuit
30.
The function of the Reset Circuit 30 is identical to the function
of the Set Circuit 26. The reset circuit responds to signals from
the Comparator 2 Circuit 28 and Detector 29. When a low or ground
signal is transmitted from the output of the Comparator 2 Circuit
28 to the reset circuit's first gate, diode 701, diode 701 conducts
and provides a low resistance path between the junction 706 and
ground. A high signal received at diode 701 from the Comparator 2
Circuit 28, indicative of the speed above the predetermined value,
is blocked by diode 701 and has no influence on the potential at
junction 706. Likewise, a low signal from Detector 29 to the reset
circuit causes diode 703 to conduct, again providing the low
resistance path to ground for the current flowing through
resistance 702. A high signal from Detector 29 indicative of an
increasing manifold pressure is blocked by diode 703 and removes
the low resistance path to ground from junction 706. High signals
received at both input gates, diode 701 and 703, permits current to
flow from B+ through resistance 702 through the two diodes 704 and
705 to the base of transistor 602, causing transistor 602 to
conduct and resets the bistable multivibrator in its initial state.
The two diodes 704 and 705 are used in this circuit to elevate the
potential required at junction 706 to make transistor 602 conduct
above the potential of the highest low signal at an input gate. A
low signal at either gate, diodes 701 or 703, or both, results in a
lower resistance path to ground, approximately two diode drops, and
terminates the current flow to the base of transistor 602. As
described above, high signals occurring at both diodes 701 and 703
apply a positive signal to the base of transistor 602, causing it
to conduct. Conduction of transistor 602 generates a low signal
which is communicated to output terminal 604 and to the base of
transistor 601 by means of resistance 605. The low signal at the
base of transistor 601 blocks the conductance of transistor 601,
which produces a high signal which is communicated to the base of
transistor 602 through resistance 603 and latches multivibrator in
the reset mode and terminates the high signal at terminal 604.
As seen from the above descriptions of the circuit details, the
deceleration control circuit accomplishes the objectives of the
invention. An inhibitory signal is developed when the engine speed
is above a predetermined level, the manifold absolute pressure is
above the predetermined level, and the manifold pressure is
decreasing. This inhibitory signal remains until the engine
operating parameters return to a normal state. The normal state as
defined by this circuit is when the manifold absolute pressure has
returned to or is above a predetermined value and the manifold
pressure is increasing.
An alternate embodiment of the inventive Deceleration Control 20 is
illustrated in FIG. 5. The embodiment is entirely dependent upon
the signals from the Manifold Pressure Sensor 18. As in the
previous embodiment reference manifold pressure signals are
developed in the Reference 1 Signal Generating Circuit 22 and
Reference 2 Signal Generating Circuit 23. The signals from the
Manifold Pressure Sensor 18 is compared with the Reference 1 and
Reference 2 signals in the Comparator 1 Circuit 27 and the
Comparator 2 Circuit 28, respectively, which produce output signal
when the manifold absolute pressure signal is greater than the
reference signal. The manifold pressure signal is also transmitted
to the Time Rate of Change Detector 29 which produces two signals
indicative of whether the manifold pressure is increasing or
decreasing. The signal from the Comparator 1 Circuit 27 and the
decreasing pressure signal (dP/dt negative) are communicated to the
Set Circuit 26 which generates a signal when it receives
simultaneous signals indicating a pressure sbove the predetermined
value and that the pressure is decreasing. The signal from the Set
Circuit 26 triggers the Output Switch 31 to change state and
produce a fuel inhibit signal which is communicated to the Fuel
Control Computer 17. The Output Switch 31 remains in this state
until it receives a signal from the Reset Circuit 30. The Reset
Circuit 30 responds to simultaneous signals from the Comparator 2
Circuit 28 indicating the manifold pressure is above a second
predetermined value and a signal from the Detector 29 indicating
the manifold pressure is increasing (dP/dt positive) generating a
signal resetting the Output Switch 31 to its initial state. This
signal terminates the fuel inhibit signal being transmitted to the
Fuel Control Computer 17 restoring normal fuel delivery to the
engine. This embodiment, as well as the one previously described,
are functional control systems based upon predetermined manifold
absolute pressures and the manifold pressure time rate of change
for determining the operator's demand for deceleration.
It will be apparent to one skilled in the art that signals from
other engine sensors may be added to the set and reset circuits to
still further refine the determination of the operator's demand for
deceleration.
The signals from the Deceleration Control 20 can be used to
terminate or modify the signals from the Fuel Control Computer 17
to the injector valves 12 as previously indicated. The deceleration
signal can be transmitted directly to the output stage of the
Computer 17 to block the fuel injection signals generated,
preventing operation of the fuel injector valves. This type of
circuit is shown in block form in FIG. 6. Signals from the Engine
Sensors 50 are transmitted to the Pulse Generator Computer 51 and
the Deceleration Control 20. The Pulse Generator Computer 51
responding to the signals from the engine sensors computes the
proper fuel requirements for efficient operation of the engine and
generates an electrical pulse, the duration of which is indicative
of the computed fuel requirements. Output Pulse Generator 52
responding to the signals from the Pulse Generating Computer 51
generates an output signal capable of activating the injection
valve 12, providing fuel delivery to the engine. The Pulse
Generating Computer 51 and the Output Pulse Generator 52 comprise
the Fuel Control Computer 17 shown in FIG. 1. The Output Pulse
Generator 52 also responds to the signal from the Deceleration
Control 20. When the Output Pulse Generator 52 receives the signal
from the deceleration control indicative of an operator's demand
for deceleration, the signal received is operable to block the
generation of output signals terminating the engine fuel
delivery.
Alternatively, the signal from the deceleration control can be used
to curtail or reduce the fuel delivery to the engine during the
deceleration period. FIG. 7 shows a block diagram of such a system.
As in FIG. 6, the Engine Sensors 50 supply signals indicative of
the engine's operating parameters to both the Pulse Generating
Computer 51 and the Inhibit Signal Generator 55. The Pulse
Generating Computer 51 generates the fuel requirements of the
engine and generates electronic pulse indicative of the computed
fuel requirement. This electrical pulse is transmitted to the
Output Pulse Generator 52 which produces an output signal capable
of activating the fuel injector valves 12.
The signal from the Inhibit Signal Generator 55 indicative of an
operator's demand for deceleration activates a Switch 53. Switch 53
responds to the pulses generated by the computer circuit and is
operable to produce an inhibitory signal systematically blocking
the signals to the fuel injector valve. The switch, in the form of
an electrical gate or counter, may produce an inhibitory signal for
every other, every third, or every fourth, etc., fuel injection
pulse received from the computer. Likewise, the switch may be
operable to produce inhibitory signals for two out of three, three
out of four, four out of five, etc., signals received from the
Computer 51. The function of the Switch 53 is to curtail the fuel
delivery to the engine upon a signal from the Inhibit Signal
Generator 55 by systematically blocking some of the fuel injection
pulses, generated by the Pulse Generating Computer 51. Inhibit
Signal Generator 55 and Switch 53 comprises an alternate embodiment
of the Deceleration Control 20 shown in FIG. 1.
Another method for curtailing the fuel delivery to the engine in
response to a deceleration command is illustrated in FIG. 8. As in
the previous figures, fuel injection pulses are transmitted to the
Output Pulse Generator 52 in accordance with the fuel requirements
of the engine, determined by the Pulse Generating Computer 51 in
response to the signals from the Engine Sensors 50. These signal
pulses are transmitted to the Output Pulse Generator 52 which
activates the fuel injection valves. Pulses are also transmitted to
a Delay Circuit 54 which generates an inhibitory pulse a fixed time
after receipt of a pulse from the Computer 51. The inhibit pulse is
communicated to the Output Pulse Generator 52, controlling the
duration of the output pulse being generated by the output pulse
generator to a shorter fixed period. The trailing edge of the pulse
from the Computer 51 communicated to the delay circuit may be used
to reset the delay circuit, terminating the inhibit pulse being
transmitted to the Output Pulse Generator 52, and restore the
output pulse generator to its normal mode of operation. The signal
from the Inhibit Pulse Generator 55 transmitted to the Delay
Circuit 54 activates the delay system producing the inhibitory
signal. The function of the Delay Circuit 54 is to curtail the fuel
delivery to the engine upon a deceleration command by terminating
the output pulses from the Output Pulse Generator 52 after a fixed
period of time, independent of the signal from the Pulse Generating
Computer 51. Inhibit Pulse Generator 55 and Delay Switch comprise
an alternate embodiment of Deceleration Control 20 shown in FIG. 1.
It should be apparent to one skilled in the art that signals from
the engine sensors could also be used to modify the delay period of
the inhibitory pulse to further reduce the exhaust emissions during
deceleration and subsequent acceleration.
While the invention has been illustrated and described as embodied
in a particular type of fuel injection control system, it is not
intended to be limited to the details shown, since various
modifications and circuit structural changes may be made without
departing in any way from the spirit of the present invention.
* * * * *