Microprocessor-based engine control system with acceleration enrichment control

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optimizing acceleration enrichment handling, and the

MICROPROCESSOR-BASED ENGINE CONTROL like. Moreover, the systems of the prior art are ex SYSTEM WITH ACCELERATION ENRICHMENT tremely expensive, difficult to repair and maintain and CONTROL are not commercially feasible at the present time.

These and other problems of the prior art, particu

BACKGROUND OF THE INVENTION larly poor drivability, results from the inability of the 1. Field of the Invention prior art systems to immediately respond to a request This invention relates generally to a method and for a rapid increase in engine speed. The failure to rap apparatus for controlling an internal combustion engine, 10 idly respond to such a request results in a lean fuel and more particularly to a microprocessor-based elec charge being delivered to cylinders which induct air tronic engine control system having a memory prepro from a higher pressure manifold but have received a grammed with various control laws and control sched quantity of fuel calculated during a lower manifold pressure creating a "stumble' condition leading to poor ules responsive to one or more sensed engine-operating drivability.

parameters and generating control signals for fuel injec 15 tion, ignition timing, EGR control, and the like. These and other problems of the prior are are solved 2. Statement of the Prior Art by the system of the present invention which utilizes a Many of the patents of the prior art recognize the program-controlled microprocessor system and means need for employing the enhanced accuracy of digital for detecting a need for acceleration enrichment for control systems for more accurately controlling one or 20 transmitting an interrupt to said microprocessor for more functions of an internal combustion engine. permitting additional fuel to be immediately applied U.S. Pat. No. 3,969,614 which issued to David F. thereto.

Moyer, et all on July 13, 1976 is typical of such systems If a previously-computed fuel charge is already being as are U.S. Pat. No. 3,835,819 which issued to Robert L. applied at time time of the interrupt, the requied addi Anderson, Jr. on Sept. 17, 1974; U.S. Pat. No. 3,904,856 tional acceleration enrichment fuel is supplied immedi which issued to Louis Monptit on Sept. 9, 1975; and 25 ately at the end of the current fuel charge. U.S. Pat. No. 3,906,207 which issued to Jean-Pierre SUMMARY OF THE INVENTION Rivere, et all on Sept. 16, 1975. All of these Patents A method and apparatus is provided for improving represent a break-away from the purely analog control systems of the past, but neither the accuracy, reliability, 30 drivability by minimizing stumble. Means are provided or number of functions controlled is sufficient to meet for detecting an operator-commanded request for a present day requirements. rapid increase in engine speed for generating an acceler Future internal combustion engines will require that ation enrichment request signal in response thereto. The emissions be tightly controlled due to ever-increasing acceleration enrichment request signal executes an in governmental regulations, while fuel consumption is 35 terrupt in a program-controlled microprocessor having minimized and drivability improved over the entire a memory means for storing look-up tables of control operating range of the engine. None of the systems of values and program means for implementing predeter the prior art provide a method and apparatus for con mined fuel control laws. The microprocessor is respon trolling the operation of an internal combustion engine sive to the receipt of said interrupt request signal for with sufficient accuracy to attain minimal emissions and immediately commanding additional fuel to be supplied minimal fuel consumption while simultaneously achiev to the engine or if a previously-computed fuel charge is ing improved drivability. currently being supplied at the moment of the interrupt, The systems of the prior art attempt to control one or then the microprocessor temporarily stores said inter more of the engine-operating functions but none at rupt and controls additional fuel to be immediately tempts to control the operation of the fuel pump, fuel 45 upon the completion of said currently-generated previ injection, engine ignition timing, on-off and/or propor ously-computed fuel charge.

tional EGR control, and the like while using feedback onThis application is one of fourteen applications filed Feb. 27, 1978, all commonly assigned and having from such devices as oxygen sensors for emission con substantially the same specification and drawings, the trol purposes or for effecting a closed loop fuel control mode of operation, and yet including provisions for fourteen applications being identified below: Serial Number Title 881321 Microprocessor-Based Electronic Engine Control System 881,322 Feedback-Compensated Ramp-Type Analog to Digital

Converter 881,323 Input/Output Electronic For Microprocessor-Based

Engine Control System 881,324 Switching Control of Solenoid Current in Fuel

Injection Systems 881,921 Dual Voltage Regulator With Low Woltage Shutdown 881,922 Oxygen Sensor Qualifier 881,923 Rationetric Self-Correcting Single Ramp Analog To

Pulse Width Modulator 881,924 Microprocessor-Based Engine Control System Acceleration

Enrichment Control 881,925 Improvements in Microprocessor-Based Engine Control

Systems 881,981 Oxygen Sensor Feedback Loop Digital Electronic Signal

Integrator for internal Combustion Engine Control 881,982 Improvements in Electronic Engine Controls System 881,983 Electronic Fuel Injection Compensation

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Serial Number Title 881,984 Ignition Limp Home Circuit For Electronic Engine

Control Systems 881,985 Oxygen Sensor Signal Conditioner

Application Ser. No. 881,321, has been printed in its entirety and the specification of that application is spe cifically incorporated herin by reference. control means is not already generating a normal I claim: fuel control pulse, and for generating an additional 1. In an internal combustion engine having an intake delayed acceleration enrichment fuel control pulse system, an exhaust system, an engine block, a plurality at the termination of and as an extension to an of cylinders disposed in said engine block, a piston existing normally-generated fuel control pulse if mounted for reciprocal movement within each of said such is currently being generated. plurality of cylinders, throttle means disposed in said 3. The improved internal combustion engine system intake system for controlling the air flow into said plu of claim 1 wherein said means for sensing at least one rality of cylinders, means generating a fuel control sig engine-operating parameter for detecting a need for nal in response to sensed engine parameters, an elec acceleration enrichment includes means responsive to tronic engine control system including means respon the rate of change of the measured manifold absolute sive to said fuel control signal for selectively supplying 20 pressure for generating a signal indicative of a need for a controlled quantity of fuel into selected one or more acceleration enrichment and for generating said accel of said plurality of cylinders, and means for controlling eration enrichment command in response thereto. the timing and duration of the ignition timing of said air 4. The improved internal combustion engine system and fuel supplied to said selected one or more cylinders; of claim 3 wherein said means responsive to the rate of said electronic engine control system comprising 25 change of said measured manifold absolute pressure program-controlled computing means, memory includes sensor means for measuring manifold absolute means for storing data representative of look-up pressure and generating an analog output signal indica tables of control schedules and control means for tive thereof and means for differentiating said analog implementing a predetermined fuel control law; output signal for detecting a rapid change therein, said means for sensing at least one engine-operating pa 30 means for differentiating including an input node, means rameter for detecting a need for acceleration en for operatively coupling said analog output signal indic richment and for generating an acceleration enrich ative of measured manifold absolute pressure to said ment command in response thereto; input node, a comparator having first and second com means responsive to said acceleration enrichment partor inputs and a comparator output, a diode having command for transmitting an acceleration enrich 35 its anode coupled to said input node and its cathode ment interrupt request signal to said computing resistively coupled to a first comparator input, resistive means, said computing means being responsive to means operatively coupling said input node to said sec said acceleration enrichment interrupt request sig ond comparator input, capacitor means coupled be nal for generating signals to implement said fuel tween a source of potential and said resistive means control law stored in said memory means and gen 40 from a low pass filter which acts as the delay to said erating an acceleration enrichment fuel pulse com analog output signal presented to said input node, said mand word signal in response thereto; and diode providing a small voltage drop difference be means responsive to said acceleration enrichment fuel tween the signals presented to said first and second pulse command word signal for initiating the im comparator inputs such that so long as said analog out mediate generation of a separate one-time accelera 45 put signal presented to said input node is a slowly rising tion enrichment fuel control pulse in response signal, indicating a normal operating engine condition thereto or, if a normal fuel control pulse is cur where no acceleration enrichment is required, the out rently being generated at the time of said accelera put of said comparator will remain in a first comparator tion enrichment interrupt request, for initiating the output state and will not generate said acceleration generation of said additional onetime acceleration 50 enrichment command, but when a fast rising analog enrichment fuel control pulse immediately upon input signal is supplied to said input node, which the completion of said currently-generated normal amounts to a change in value of greater than the voltage fuel control pulse. drop across said diode, a high signal will be supplied to 2. In an internal combustion engine, an engine control said first comparator input since the low pass filter system including means responsive to a fuel control 55 effect of said capacitor means and resistive means cou pulse for supplying a controlled quantity of fuel to said pling said input node to said second comparator input engine and further including electronic engine control will cause a slower rise at said second input, thereby means responsive to measured engine-operating param causing the output of said comparator to generate said eters for controlling the generation of said fuel control acceleration enrichment command, the voltage supplied pulse, the improvement comprising: 60 to said comparator input catching up to the level of means for detecting the need for acceleration enrich voltage supplied to said first comparator input as said ment and for generating an interrupt signal indica capacitive means becomes charged to the level of said tive thereof; analog input signal to again cause the output of said means responsive to said interrupt signal indicative of comparator to return to said first state and terminate a need for acceleration enrichment for enabling 65 said acceleration enrichment signal such that the pulse said engine control system to immediately generate width duration of said acceleration enrichment com an additional separate acceleration enrichment fuel mand is indicative of the magnitude of the rate of control pulse in response thereto if said engine change of said analog input signal and therefore deter

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minative of the amount of acceleration enrichment re 8. The improved internal combustion engine system quired. ... . . . . . . . . . . ". . . . of claim 7 wherein said system includes means for gen 5. The improved internal combustion engine system erating a "cranking mode' signal indicative of said of claim 4 wherein said system includes means for gen internal combustion engine being in a starting state and erating a "cranking mode" signal indicative of said means responsive to said "cranking mode" signal for internal combustion engine being in a starting state and disabling the output of said comparator to prevent the means responsive to said "cranking mode' signal for generation of said acceleration enrichment command disabling the output of said comparator to prevent the during engine starting and the like. generation of said acceleration enrichment command 10 9. The improved internal combustion engine system during engine starting and the like. of claim 1 wherein said means responsive to said accel 6. The improved internal combustion engine system eration enrichment command further includes, in addi of claim 1 wherein said throttle means includes a throt tion to said means for generating said immediate one tle plate whose angular position controls the flow of air time acceleration enrichment pulse, an additional means into said plurality of cylinders and wherein said means for modifying the operation of said program means for for sensing at least one engine-operating parameter for 15 effecting a long-term acceleration enrichment alteration detecting a need for acceleration enrichment includes of said tonormally-generated fuel control pulse in re means responsive to the rate of change of said throttle sponse said acceleration enrichment interrupt re angle for generating a signal indicative of a need for quest.

acceleration enrichment and for generating said accel 20 10. The improved internal combustion engine system eration enrichment command in response thereto. of claim 1 wherein said computer means further in 7. The improved internal combustion engine system table cludes memory means for storing at least one look-up of claim 6 wherein said means responsive to the rate of richment containing a control schedule of acceleration en change of said measured throttle angle includes sensor function fuel control pulse modifier values stored as a means for measuring throttle angle and generating an 25 said systemoffurtherengine coolant temperature and wherein analog output signal indicative thereof and means for coolant temperatureincludes means for measuring engine and generating a signal indicative differentiating said analog output signal for detecting a thereof, means responsive to said signal indicative of rapid change, therein, said means for differentiating measured engine coolant temperature for generating a including an input node, means for operatively coupling coolant temperature word indicative thereof, said mem said analog output signal indicative of measured throttle 30 ory means being addressed by said coolant temperature angle to said input node, a comparator having first and word and said computing means interpolating between second comparator inputs and a comparator output, a coolant diode having its anode coupled to said input node and particulartemperature word addresses for calculating a acceleration enrichment fuel control pulse its cathode resitively coupled to a first comparator in modifier value corresponding to the actual measured put, resistive means operatively coupling said input 35 value of engine coolant temperature represented by said node to said second comparator input, capacitor means coolant temperature word, said computing means utiliz coupled between a source of potential and said resistive ing said particular modifier value in executing means from a low pass filter which acts as the delay to gram means to implement said fuel control said law pro and said analog output signal presented to said input node, calculate an acceleration enrichment-modified fuel said diode providing a small voltage drop difference between the signals presented to said first and second pulse command word in response thereto. comparator inputs such that so long as said analog out claim 2The 11. improved internal combustion engine of wherein said means responsive to said interrupt put signal presented to said input node is a slowly rising signal indicative of said need for acceleration enrich signal indicating a normal operating engine condition ment for immediately generating said additional one where no acceleration enrichment is required, the out 45 time initial acceleration enrichment fuel control pulse put of said comparator will remain in a first comparator further includes means responsive to said normally output state and will not generate said acceleration computed primary fuel control pulse being generated enrichment command, but when a fast rising analog during generation of said one-time acceleration enrich input signal is supplied to said input node which ment fuel control pulse for delaying the generation of amounts to a change in value of greater than the voltage 50 said normally-generated fuel control pulse until deter drop across said diode, a high signal will be supplied to mination of said one-time acceleration enrichment fuel said first comparator input since the low pass filter control pulse.

effect of said capacitor means and resistive means cou 12. A method for maintaining smooth engine perfor pling said input node to said second comparator input mance in an internal combustion engine comprising the will cause a slower rise at said second input thereby 55 steps of:

causing the output of said comparator to generate said monitoring the value of one of manifold absolute acceleration enrichment command, the voltage supplied pressure and throttle angle; to said comparator input catching up to the level of detecting a rapid change in said monitored value of voltage supplied to said first comparator input as said one of said manifold absolute pressure and throttle capacitive means becomes charged to the level of said 60 angle;

analog input signal to again cause the output of said generating an acceleration enrichment interrupt re comparator to return to said first state and terminate quest in response to the detection of said rapid said acceleration enrichment signal such that the pulse change in said monitored value of one of said mani width duration of said acceleration enrichment com fold absolute pressure and throttle angle; mand is indicative of the magnitude of the rate of 65 measuring the actual value of engine coolant temper change of said analog input signal and therefore deter ature;

minative of the amount of acceleration enrichment re computing an initial and immediate Tip-In accelera quired. tion enrichment command as a function of said

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measured value of engine coolant temperature to said plurality of cylinders, means for measuring at least determine the initial and immediate amount of fuel one of said throttle angle and the manifold absolute to be injected into said engine for acceleration pressure existing in said intake system, means responsive enrichment purposes; to the measurement of said at least one of said throttle immediately generating a Tip-In acceleration enrich angle and said manifold absolute pressure for generating ment fuel control pulse in response to said Tip-In a signal indicative thereof, means responsive to said acceleration enrichment command to supply a con signal indicative of the measured value of at least one of trolled quantity of fuel to a selected one or more of said throttle angle and manifold absolute pressure for the cylinders of said internal combustion engine sensing a rapid change therein and generating an accel unless said internal combustion engine is currently O eration enrichment interrupt request in response generating a normally-computed main fuel control thereto, a microprocessor-based electronic engine con pulse; trol system including a computer means, a memory temporarily storing said acceleration enrichment in means operatively coupled to said computer means, terrupt request for delaying the computing of said control means stored within said memory means for acceleration enrichment command and the genera 15 generating control signals to implement at least one fuel tion of said Tip-In acceleration enrichment fuel control law and for performing calculations for interpo control pulse whenever said normally-computed main fuel control pulse is currently being gener lating between addresses in said memory means, said memory means storing a plurality of look-up tables of ated; and otherwise temporarily storing said acceleration enrichment re 20 modifier values representing control surfaces utilized in implementing said at least one fuel control law and quest and delaying the computing of said accelera being addressable tion enrichment command and the generation of ing parameters, thebyimprovement various measured engine-operat comprising said com said Tip-In acceleration enrichment fuel control puter means being responsive to said acceleration en pulse if said normally-calculated main fuel control richment request for addressing one of said plurality of pulse is currently being generated; and 25 adding said Tip-In acceleration enrichment fuel con look-up menting tables stored in said memory means and imple said program means to interpolate between trol pulse to said normally-calculated main fuel stored values for computing an acceleration enrichment control pulse immediately upon its termination for command, means reponsive to said acceleration enrich extending the pulse-width duration of said normal ment command for immediately generating a Tip-In ly-calculated main fuel control pulse by the pulse 30 fuel control pulse whose pulse-width is dictated by the width of said Tip-In acceleration enrichment fuel control pulse so as to compensate for rapid changes value calculated from interpolating the control surface of said at least one look-up table stored in said memory in acceleration and ensure smooth running engine means if the normally-calculated main fule control pulse operations.

is not currently being generated but for storing and 13. The method of claim 12 including the additional 35 delaying steps of computing said normally-calculated main fuel the generation of said Tip-In fuel control pulse control pulses subsequent to the generation of said ac in response to said acceleration enrichment request if celeration enrichment interrupt request as a function of said normally-computed main fuel control pulse is cur engine RPM, air temperature, coolant temperature and rently being generated and immediately adding said the like to gradually increase or decrease the normally 40 Tip-In fuel control pulse at the termination of said main computed value thereof for long-term acceleration en fuel control pulse for extending same and therefore richment compensation. increasing the quantity of fuel supplied to said selected 14. In an internal combustion engine system including one or more of said plurality of cylinders for enriching an intake system, an exhaust system, throttle means the fuel mixture existing therein for compensating for disposed at least partially within said intake system for 45 the detected acceleration and maintaining smooth en selectively controlling the flow of air into said engine, gine operations.

said throttle means including a throttle plate whose 15. The improved engine-operating system of claim angle determines said air flow, an engine block, the 14 wherein said computer means includes means further plurality of cylinders disposed in said engine block, a responsive to said acceleration enrichment interrupt for piston operatively disposed for reciprocal movement 50 causing said program means to alter the computation of within each of said plurality of cylinders in response to the next normally-calculated main fuel control pulse for the combustion of fuel and air therein, means responsive increasing and decreasing same to provide for a long to fuel control pulses for selectively controlling the term gradual acceleration is enrichment compensation.

quantity of fuel supplied to a selected one or more of